Neurology

Question 1

In the resting state, the interior of the cell is ……….. with respect to the exterior, and this charge difference is maintained primarily via the Na+2-K+ ATPase
pump that extrudes ……Na+2 molecules in exchange for moving………. K+ molecules ……….. the cell.

Answer 1

In the resting state, the interior of the cell is negative with respect to the exterior, and this charge difference is maintained primarily via the Na+2-K+ ATPase
pump that extrudes 3 Na+2 molecules in exchange for moving 2 K+ molecules into the cell.
Importantly, this pump requires energy to maintain the interior of the cell approximately negative with respect to the exterior.

Question 2

When the cell is “excited” its resting
membrane potential moves toward positive until threshold is reached (depolarization), and an action potential is generated. This occurs primarily via…..?

Answer 2

Primarily via Na+2 entering the interior of the cell.

Question 3

After threshold is reached and the action potential is generated, …….. will then be extruded, the molecular charge at the cell membrane will become more
………………., and the cell will repolarize to its resting membrane potential.

Answer 3

After threshold is reached and the action potential is generated, Na+2 will then be extruded, the molecular charge at the cell membrane will become more
negative, and the cell will repolarize to its resting membrane potential.

Question 4

On one hand, the cell is available to be excited by excitatory ………….potentials. This stimulation will result in depolarization. In opposition, the cell may be inhibited or prevented from depolarizing by stimulation from inhibitory ……….. potentials.

Answer 4

On one hand, the cell is available to be excited by excitatory postsynaptic potentials. This stimulation will result in depolarization. In opposition, the cell may be inhibited or prevented from depolarizing by stimulation from inhibitory postsynaptic potentials.

In general, then, neuronal activity may be relatively excitatory, relatively inhibitory, or neutral if equal degrees of excitation and inhibition exist concurrently.

Question 5

A stimulus is “recognized” by the nervous system through a receptor. Once the receptor is activated, this “information” is transmitted through ………… (“going toward”) pathways to reach a neuronal cell body.
Once the cell body is activated, further transmission of such information is directed away from the cell body (……………….transmission) to ultimately connect through a synapse with an “effector organ.”

Answer 5

Once the receptor is activated, this “information” is
transmitted through afferent (“going toward”) pathways to reach a neuronal cell body.
Once the cell body is activated, further transmission of such information is directed away from the cell body (efferent transmission) to ultimately connect through a synapse with an “effector organ.”

Question 6

What is an effector organ?

Answer 6

In some instances that effector organ is another nerve or nerveelement; in other settings this effector organ may be a muscle or gland. If the effectororgan is a skeletal or somatic muscle, then the synapse is referred to as a neuromuscular junction.

Question 7

Consciousness is ultimately attributed to normal functions within the intracranial nervous structures, such as the cerebral hemispheres. Cerebral hemispheric function contributes to sensory integration as in the somatosensory (parietal) cortex, occipital cortex (………), and temporal cortex (………) (which senses)

Answer 7

Consciousness is ultimately attributed to normal functions within the intracranial nervous structures, such as the cerebral hemispheres. Cerebral hemispheric function contributes to sensory integration as in the somatosensory (parietal) cortex, occipital cortex (vision), and temporal cortex (hearing).

Other regions of the cerebral hemispheres are responsible for “willed” behavior and subsequent movements or reactions.

Question 8

Definition of proprioception?

Answer 8

Often defined as knowledge of one’s position. Proprioception is a sensory or afferent process that can be thought of as akin to “input positional data” or where there is a part of the body “sensed” to exist at all points in time.

Question 9

Definition of kinesthesia?

Answer 9

An awareness of the precise position and movement of the parts of the body and especially the limbs

Question 10

The most common stimulus for proprioception or kinesthesia? Results of this?

Answer 10

Gravitational force. This results in stretch or tension in muscles, tendons, or even joints

Question 11

What occurs following receptor activation in areas due to alterations in gravitational force?

Answer 11

Nervous system fibers project afferently to synapse on either (1) local interneurons or motorneurons or (2) neurons in the intracranial nervous systems structures (brainstem, cerebellum, or supratentorial structures).

Question 12

Proprioception is often divided into “conscious” or “unconscious.” What is the difference?

Answer 12

Conscious proprioception results from projections to conscious areas of the nervous system in the cerebral cortex.
Unconscious proprioception projections often terminate in the cerebellum or brainstem nuclei or in regions where conscious awareness of these functions in not necessary.

Question 13

The …………… functions allow for determination of spacial awareness (input data). Ultimately, however, subsequent ………… pathway activation results in activation of motor neurons, which in turn activate various muscles via activation of the neuromuscular junction.

Answer 13

The afferent functions allow for determination of spacial awareness (input data). Ultimately, however, subsequent efferent pathway activation results in activation of motor neurons, which in turn activate various muscles via activation of the neuromuscular junction. For static posture, gravitation forces result in activation of “antigravity muscles.” When these muscles or muscle groups are activated, the overall clinical characteristic is one of “extension,” sometimes referred to as spasticity.

Question 14

For static posture, gravitation forces result in activation of “……………muscles.” When these muscles or muscle groups are activated, the overall clinical characteristic is one of “extension,” sometimes referred to as …………….

Answer 14

For static posture, gravitation forces result in activation of “antigravity muscles.” When these muscles or muscle groups are activated, the overall clinical characteristic is one of “extension,” sometimes referred to as spasticity.

Question 15

In general, the nervous system can be conceptualized into two parts: which ones?

Answer 15

A more centralized controlling system (UMN) and a local reflex system (LMN) (Figure 257-3).

Question 16

The central controlling nervous system is analogous to? (which areas)?

Answer 16

The brain, brainstem, cerebellum, and portions of the spinal cord that contain or are important for both ascending and descending transmission of information.
This functional concept of a central controlling system is often referred to as the upper motor neuron (UMN) system.

Question 17

Conversely, because the central nervous system does not directly connect to the organs or muscles, a second functional nervous system is necessary for stimulation of a muscle or organ. Which one?

Answer 17

This system is referred to as the lower motor neuron (LMN). The LMN is analogous to the efferent (motor) peripheral nervous system and the effector organs (primarily muscles).

Question 18

Which parts are included in the LMN?

Answer 18

This system is conceptualized as more rudimentary, or reflex in function, with these reflex functions being primarily performed by components of the peripheral nervous system and cranial nerves. Using this strict definition, other functional components of the LMN, such as the cell body of the motor neuron in the ventral gray matter of the spinal cord, would not be included in the peripheral nervous system. Functionally, however, a lesion of the peripheral nerve or cell body would result in identical clinical signs as a lesion in the peripheral nerve. Therefore, the terms peripheral nervous system and LMN are usually used interchangeably.

Question 19

Body functions such as walking, barking, eating, drinking, urinating, and blinking through observation of an animal to determine if the nervous system is functioning properly.

These functions are performed via the central controlling systems’ (……….) influence on the local reflex system (……….), or in some instances (i.e., spinal reflex function) by the independent function of the …………………….

Answer 19

These functions are performed via the central controlling systems’ (UMNs) influence on the local reflex system (LMNs), or in some instances (i.e., spinal reflex function) by the independent function of the local reflex system.

Question 20

If we determine that a function is abnormal, then we are uncertain if the abnormality resides in the UMN, the LMN, or both.
We then evaluate the function of the ………., for example, by assessing local spinal reflex function. If the local spinal reflex function is normal, and the animal is dysfunctional, then we assume that the problem lies within the …………What if, however, the LMN is dysfunctional: can we assess the function of the UMN?

Answer 20

We then evaluate the function of the LMN, for example, by assessing local spinal reflex function. If the local spinal reflex function is normal, and the animal is dysfunctional, then we assume that the problem lies within the UMN. If, however, the LMN is dysfunctional, we have lost the ability to assess for a concurrent UMN problem.

Question 21

Abnormalities of movement may be categorized as either ……… or ………………. . ……………. movements, however, are usually only initiated consciously but are coordinated or controlled at a more subcortical level because it would exceedingly inefficient for an animal to have to actually “think” about the infinite dynamic positions of the body during something as simple as walking or running.

Answer 21

Abnormalities of movement may be categorized as either voluntary or involuntary. Voluntary movements, however, are usually only initiated consciously but are coordinated or controlled at a more subcortical level because it would exceedingly inefficient for an animal to have to actually “think” about the infinite dynamic positions of the body during something as simple as walking or running.

Question 22

Similar to body posture, proprioceptive sensory input and subsequent motor activation are important components of walking, gaiting, and other movements of the head, trunk, and limbs. Abnormalities of these functions, therefore, can result either from?

Answer 22

Abnormal proprioceptive inputs, abnormal motor activation, or dysfunction at the neuromuscular junction or motor itself.

Question 23

Some movement patterns such as ataxia are more characteristic of sensory abnormalities, whereas others may be more characteristic of primary motor pathway involvement. Paresis, however, may result from……….?

Answer 23

Paresis, however, may result from either a sensory or motor abnormality and is therefore not a pathognomonic finding of either.

Question 24

Involuntary movement abnormalities are often again primarily assumed in animals, as the willed motivation for such movements seems illogical. Involuntary movements may have characteristic qualities such as….?

Answer 24

Myoclonus and tremor.

Question 25

Pinprick pain can be elicited by stimulation of the skin with a fine needle. This information is transmitted initially in thin, ...............fibers (A III or A delta fibers)The sensations are conducted relatively quickly, are accurately localized, and do not outlast the stimulus. Pinprick information is transmitted centrally in the spinothalamic tract.

Answer 25

In thin, myelinated fibers (A III or A delta fibers).

Question 26

Pain receptors in the skin are more numerous than pressure receptors. True pain is initially carried in thin, ............ (C) fibers that enter into the substantia gelatinosa (dorsolateral tract or Lissauer's tract; Rexed's lamina II). A delta fibers are responsible for initial pain and C fibers are responsible for delayed pain.

Answer 26

In thin, unmyelinated (C) fibers

Question 27

A pain stimulus results in an inhibition of .........fibers, resulting in projection of pain information.

Answer 27

A pain stimulus results in an inhibition of inhibitory pain fibers, resulting in projection of pain information.

Question 28

Pain can have numerous qualities. Initial pain is ....... and ......... Delayed pain is ........and has a latency of 0.5 to 1.0 second. Deep pain is ...........and poorly localizable. Visceral pain is ....................., and poorly localized.

Answer 28

Pain can have numerous qualities. Initial pain is sharp and localizable. Delayed pain is dull and has a latency of 0.5 to 1.0 second. Deep pain is dull and poorly localizable. Visceral pain is dull, diffuse, and poorly localized.

Question 29

The body itself may inhibit pain conduction recognition through central and peripheral antinociceptive mechanisms. Stimulation of many central nervous system areas may result in pain relief. This is likely mediated through the release or alteration in concentrations of neurotransmitters such as?

Answer 29

Such as endorphins, enkephalins, serotonin, norepinephrine, and others.

Question 30

Additionally, pain transmission may be blocked locally at the spinal cord level in the....................................

Answer 30

Additionally, pain transmission may be blocked locally at the spinal cord level in the substantia gelatinosa (gating). These endogenous antinociception mechanisms may be a physiologic explanation for why acupuncture and acupressure may be beneficial.

Question 31

The autonomic system components of the nervous system subserve many of the homeostatic functions of the body. These systems are often associated with internal organ or visceral functions. These systems are based on a two-neuron concept of a ................... and a ...................nerve.

Answer 31

Preganglionic and a postganglionic nerve. These nerves may be influenced by other neuronal systems from the intracranial structures or spinal cord.

Question 32

The ........................is an influential controlling center with regard to autonomic functions.

Answer 32

The hypothalamus

Question 33

The neuronal functions of the autonomic systems are usually categorized as either ................... or ..............................

Answer 33

sympathetic or parasympathetic

Question 34

The parasympathetic systems are important for functions such as pupillary ...................., salivation, urination, and defecation.

Answer 34

Pupillary constriction

Question 35

Neurons functioning in the parasympathetic system are concentrated where?

Answer 35

In some cranial nerves and in the pelvic areas of the body.

Question 36

Cranial nerves (CNs) III (.........), VII (..........), IX (...........), and X (vagus) have associated parasympathetic functions.

Answer 36

Cranial nerves (CNs) III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus) have associated parasympathetic functions.

Question 37

CNs III and VII tend to be contained in and around ............., whereas CN IX, and especially CN X, innervate visceral structures of the ...........................(4)

Answer 37

CNs III and VII tend to be contained in and around the head, whereas CN IX, and especially CN X, innervate visceral structures of the pharynx, larynx, thoracic, and abdominal cavities.

Question 38

In the two-neuron concept, the parasympathetic system tends to have relatively ................ preganglionic neurons. The postganglionic neurons tend to be ............. and reside intimately with the effector organ.

Answer 38

In the two-neuron concept, the parasympathetic system tends to have relatively longer preganglionic neurons. The postganglionic neurons tend to be short and reside intimately with the effector organ. For ex: The parasympathetic preganglionic cell bodies that are responsible for pupillary constriction are present in the parasympathetic nucleus of the oculomotor nerve in the brainstem. The preganglionic axons exit the brainstem as a component of the oculomotor nerve and project to the iris. Within the iris the preganglionic fibers terminate on the postganglionic fibers, which, being already in the iris, are relatively shorter in length.

Question 39

The sympathetic neuronal system is concentrated primarily where?

Answer 39

In the thoracolumbar region of the spinal cord.

Question 40

Cell bodies of preganglionic axons of the sympathetic neuronal system are found where?

Answer 40

In the gray matter between the dorsal and ventral horns (intermediolateral gray matter). The preganglionic cell bodies are influenced by descending neurons from the intracranial nervous system via projections through the cervical spinal cord. As an example, for pupillary dilation, a stimulus such as a loud sound may be transmitted into the intracranial structures. Subsequently, axons of the central sympathetic pathways are excited and transmit information caudally through the brainstem and cervical spinal cord (the lateral tectotegmental spinal pathway) to terminate on the preganglionic cell bodies in the cranial thoracic spinal cord segments T1-T3. The preganglionic cell body is excited and sends its axons out of the intervertebral foramen, through the thoracic cavity and thoracic inlet, cranially in the cervical area in the vagosympathetic trunk to terminate on the postganglionic sympathetic cell bodies in the cranial cervical ganglion just caudal to the ear. The postganglionic nerves send axons in through, along the floor, and then out of the skull to eventually terminate in the iris and periocular structures. The sound stimulus that initially excites the sympathetic system ultimately results in dilation of the pupil. In this example, both the preganglionic and postganglionic sympathetic nerve systems travel relatively longer distances to reach the effector organ.

Question 41

Does urination involve conscious or unconscious reflex modalities?

Answer 41

Urination involves both conscious and unconscious (reflex) modalities.

Question 42

Conscious urination involves the............ Unconscious urination involves the ............ and the parasympathetic and sympathetic systems within the.............. and peripheral nerves.

Answer 42

Conscious urination involves the cerebral cortex. Unconscious urination involves the brainstem and the parasympathetic and sympathetic systems within the spinal cord and peripheral nerves.

Question 43

Simplistically, the ............... system prevents while the .................system allows for urination.

Answer 43

Simplistically, the sympathetic system prevents while the parasympathetic system allows for urination.

Question 44

Urination is a reflex function, the purpose of which is to void urine from the body. This reflex most likely involves brainstem structures, as well as local spinal cord segments, and therefore may be termed a suprasegmental reflex. Normal urination requires the coordinated function of both the peripheral and central nervous systems. Which peripheral nerves innervate the bladder?

Answer 44

The pelvic, pudendal, and hypogastric.

Question 45

Where are the UMN respiratory centers located?

Answer 45

In the pons and medulla oblongata of the brainstem.[4]

Question 46

How is the respiration controlled in the medulla?

Answer 46

In the medulla there are dorsal and ventral respiratory nuclear groups that control respiration, as well as a chemosensitive area that senses changes in CO2 concentration via the formation of H+ ions.

Question 47

Besides direct stimulation of the respiratory center, afferent information associated with respiration is projected to the respiratory center from the carotid bodies (chemoreceptors) through the ...................... nerve and the aortic bodies through the ................... nerve.

Answer 47

Besides direct stimulation of the respiratory center, afferent information associated with respiration is projected to the respiratory center from the carotid bodies (chemoreceptors) through the glossopharyngeal nerve and the aortic bodies through the vagus nerve.

Question 48

Where is the pneumotactic center which increases the number of breaths/min?

Answer 48

In the pons

Question 49

Where is the apneustic center that prevents the switch off of respiration.

Answer 49

At the pons/medulla junction

Question 50

From the brainstem centers in the pons and medulla, the signal for respiration travels caudally through the cervical and cranial thoracic spinal cord to the LMNs for respiration. These LMNs are the ...............nerve (spinal segments C4-C7) that innervates the diaphragm and the .............. nerves (from the corresponding segmental spinal cord segments in the thoracic area) to the intercostal muscles.

Answer 50

These LMNs are the phrenic nerve (spinal segments C4-C7) that innervates the diaphragm and the intercostal nerves (from the corresponding segmental spinal cord segments in the thoracic area) to the intercostal muscles.

Question 51

There are numerous nonneurological influences upon respiration. For example, an increase in body temperature increases respiration: How?

Answer 51

Both by direct effects on the respiratory center and indirectly by increasing metabolism with subsequent CO2 production.

Question 52

In dogs and cats, panting may be used as a heat-dissipating mechanism. When the temperature of the blood increases, the ................signals a panting center to increase respirations. The panting center is closely related to the pneumotaxic center.

Answer 52

The hypothalamus

Question 53

Cardiovascular Functions: Vasomotor tone is maintained through interaction between the peripheral receptors and the vasomotor center in the brainstem. The peripheral receptors are baroreceptors (spray-type nerve endings located in the walls of arteries being extremely abundant in (1) the wall of the internal .............slightly above the carotid bifurcation in the carotid sinus and (2) in the wall of the aortic arch.

Answer 53

(1)internal carotid artery and (2) in the wall of the aortic arch.

Question 54

Information from the baroreceptors is transmitted from the carotid sinus through the ...................nerve to the solitary tract in the medulla .................... Information from the arch of the aorta is transmitted through the ............. nerve. This information eventually reaches the vasomotor center in the reticular substance of the .................... and the lower .............. This area transmits information down the spinal cord through sympathetic vasoconstrictor fibers to the blood vessels of the body.

Answer 54

Information is transmitted from the carotid sinus through the glossopharyngeal nerve to the solitary tract in the medulla oblongata. Information from the arch of the aorta is transmitted through the vagus nerve. This information eventually reaches the vasomotor center in the reticular substance of the medulla oblongata and the lower pons. This area transmits information down the spinal cord through sympathetic vasoconstrictor fibers to the blood vessels of the body.

Question 55

Within the vasomotor center there are functionally different areas. A vasoconstrictor area (also called C 1) in the upper medulla and lower pons: The neurotransmitter is ......................, and these neurons excite faso.......... neurons. A vasodilator area (also called A 1) in the ventrolateral portion of the lower half of the medulla: These neurons secrete ................, but these fibers project upward to the vasoconstrictor area and inhibit its activity.

Answer 55

A vasoconstrictor area (also called C 1) is found bilaterally in the upper medulla and lower pons.[4] The neurotransmitter is norepinephrine, and these neurons excite vasoconstrictor neurons. A vasodilator area (also called A 1) is found bilaterally in the ventrolateral portion of the lower half of the medulla. These neurons also secrete norepinephrine, but these fibers project upward to the vasoconstrictor area and inhibit its activity.

Question 56

The sensory area of the vasomotor center is located bilaterally in the solitary tract in the dorsolateral part of the ..............and lower........... This area receives information from CN ...... and CN .......and projects this information to the vasodilator and vasoconstrictor centers.

Answer 56

The sensory area of the vasomotor center is located bilaterally in the solitary tract in the dorsolateral part of the medulla and lower pons.[4] This area receives information from CN IX and CN X and projects this information to the vasodilator and vasoconstrictor centers.

Question 57

The vasomotor center also controls ............ in addition to vascular tone.

Answer 57

The vasomotor center also controls heart rate in addition to vascular tone. The lateral parts of the vasomotor center transmit information to excite the sympathetic nerves and increase heart rate and contractility. The medial part transmits information to decrease heart rate.

Question 58

What else can influence the vasomotor center?

Answer 58

UMNs from the reticular formation, diencephalon, and cerebral cortex may also influence the vasomotor center.

Question 59

The cough reflex occurs when the bronchi and trachea are irritated by a foreign substance. The.......... and ............are especially sensitive.

Answer 59

The cough reflex occurs when the bronchi and trachea are irritated by a foreign substance. The larynx and carina are especially sensitive.

Question 60

Cough reflex: Afferent impulses pass from the respiratory passages through the ........... nerve to the ...............

Answer 60

Afferent impulses pass from the respiratory passages through the vagus nerve to the medulla oblongata.

Question 61

Cough reflex: how does this occur? Do the abdominal muscles contract? Do the intercostal muscles contract?

Answer 61

This results when a large volume of air is inspired and the vocal cords shut tightly to entrap the air in the lungs. The abdominal muscles forcefully contract, pushing against the diaphragm while the intercostal muscles also forcefully contract. The vocal cords and epiglottis are suddenly opened wide and the air is forcefully ejected from the lungs.

Question 62

The sneeze reflex is similar to the cough reflex. Irritative stimuli to the nasal passages excite CN .......... to the .......... Reflex events are similar to that of a cough except that the uvula is depressed to allow a large amount of air to pass through the nasal passages.

Answer 62

The sneeze reflex is similar to the cough reflex. Irritative stimuli to the nasal passages excite CN V to the medulla. Reflex events are similar to that of a cough except that the uvula is depressed to allow a large amount of air to pass through the nasal passages.

Question 63

Hunger may be elicited by a number of stimuli. Do mechanoreceptors detecting stretch of the stomach wall play a major role?

Answer 63

Mechanoreceptors detecting stretch of the stomach wall may play a minor role.

Question 64

Where are glucoreceptors located? Function?

Answer 64

In the diencephalon, liver, stomach, and small intestine, signaling a reduced availability of glucose and stimulating hunger.

Question 65

Other regulators of hunger (besides mechanorecpetors and glucoreceptors?)

Answer 65

Other long-term regulators of hunger include thermoreceptors (which sense body heat, directly proportionally to energy utilization) and liporeceptors (sensing amounts of body fat). The role of these stimuli for appetite is suggested but not proven.

Question 66

Satiety is the process that stops feeding. There is both a preabsorptive and postabsorptive satiety. What does the preabsorbtive phase result from? The postabsorbtive phase?

Answer 66

The preabsorptive phase results from the feeding behavior itself before absorption of nutrients. Postabsorptive satiety is most likely dependent upon adequacy of nutrient intake.

Question 67

Preabsorptive satiety is the result of stimulating a variety of receptors; such as?

Answer 67

Olfactory; gustatory; mechanoreceptors of the mouth, throat, and esophagus; and, most importantly, stretch receptors of the stomach. Chemoreceptors in the stomach, for assessment of glucose and amino acid content of food, may also be important.

Question 68

Postabsorption satiety is dependent upon?

Answer 68

The availability of glucose, increased heat production, and changes in fat metabolism induced with feeding.

Question 69

Central recognition of hunger occurs?

Answer 69

In the hypothalamus. The cortex and limbic system influence these centers, and to complete the eating process, complex motor integration is necessary to perform the motor acts required.

Question 70

What are nonrenal losses of fluid?

Answer 70

Nonrenal losses, such as through the respiratory or gastrointestinal tract, are normally not perceivable and are, therefore, referred to as insensible losses.

Question 71

Body water depletion results in hypovolemia, hyp...osmolality of the extracellular fluid (ECF), or both.

Answer 71

Body water depletion results in hypovolemia, hyperosmolality of the extracellular fluid (ECF), or both.

Question 72

Hypovolemia and hyperosmolality of the extracellular fluid signal numerous physiologic adaptations to counterbalance the effects of the water loss. Important physiologic adaptations include?

Answer 72

Include release of antidiuretic hormone (ADH) and stimulation of thirst. Both of these adaptations tend to increase body water, the latter through stimulation of drinking. ADH increases water reabsorption and conservation by the kidney.

Question 73

An ex of a nondipsetic source of water?

Answer 73

An example of a nondipsetic source of water is the water contained in food.

Question 74

........... is signaled by a physiologic water need and is the ultimate physiologic safeguard against dehydration.

Answer 74

Thirst

Question 75

Thirst is recognized primarily within the ....................?

Answer 75

Thirst is recognized primarily within the hypothalamus of the diencephalon. This area of the hypothalamus responsible for thirst is close to, but different from, the areas associated with ADH production.

Question 76

Other areas that also may play a role in thirst?

Answer 76

Extrahypothalamic areas of the brain such as the amygdala and subcommissural organ may also play a role in thirst and drinking. Additional sensory receptors for thirst may occur in the mouth, pharynx, and vascular system such as the portal system.

Question 77

The hypothalamic receptor cell necessary for thirst recognition is referred to as an...........? How does this work?

Answer 77

An osmoreceptor. When the ECF is hyperosmolar relative to intracellular fluid (ICF), these cells lose water and shrink. This shrinkage signals the need for drinking.

Question 78

The most potent osmole stimulating thirst?

Answer 78

Sodium (glucose or urea does not stimulate thirst according to experiments)

Question 79

Although ECF hyperosmolality is an important stimulus for thirst, other effects of body water depletion can also signal thirst. Such as?

Answer 79

-Hypovolemia can be a potent stimulator of thirst, with a decrease in vascular volume of between 5% and 10% being necessary to result in drinking. -Stretch receptors or humoral factors such as those of the renin/angiotensin system may stimulate thirst. -Additional receptors in the mouth detecting dryness of the mucous membrane may elicit or alter thirst. I -In comparison, plasma osmolality needs to increase as little as 5% above normal to stimulate thirst equally. Therefore, hyperosmolality and hypovolemia/hypotension can occur concurrently or independently to stimulate thirst. These two factors appear synergistic in their effects on thirst. When an animal is hypotensive, the osmoreceptor threshold is altered so that a smaller degree of osmolality increase is required to result in thirst. Similarly, in a hypervolemic or hypertensive animal, a greater increase in osmolality is required to stimulate thirst equally.

Question 80

Neurologic examination: kolla!!

Answer 80

Video clips for this chapter, which can be found on the companion Expert Consult Web site, demonstrate various components of the neurologic examination and to show the salient abnormalities associated with the most common neuroanatomic diagnoses.

Question 81

The neurologic examination can be divided into five parts. Which ones?

Answer 81

Evaluation of (1) sensorium and behavior; (2) posture and gait; (3) postural reactions; (4) muscle mass, tone, spinal reflexes, and cutaneous sensation; and (5) cranial nerves.

Question 82

Recumbency may be associated with disorders in which areas? Can lesions in these areas affect the sensorium

Answer 82

Brainstem, cervical spinal cord, or diffuse neuromuscular disorder (NMDs). Of the three localizations, only brainstem lesions should affect the sensorium.

Question 83

An alteration in sensorium is typically due to a disturbance in the ascending reticular activating system (ARAS) and/or limbic system components of the ................. or ...................(........................).

Answer 83

An alteration in sensorium is typically due to a disturbance in the ascending reticular activating system (ARAS) and/or limbic system components of the cerebrum or rostral brainstem (diencephalon).

Question 84

Severe intracranial lesions may lead to two separate opisthotonic postures: which ones?

Answer 84

Decerebrate or decerebellate rigidity. -Decerebrate rigidity is characterized by opisthotonus with rigid extension of the neck and all four limbs, typically associated with midbrain or rostral cerebellar lesions. -Decerebellate rigidity results from severe cerebellar lesions and is characterized by opisthotonus with extensor rigidity of the limbs, but with the hips flexed.

Question 85

Pleurothotonus refers to?

Answer 85

The deviation of the head and neck to one side and may be present with mid to rostral brainstem or cerebral lesions.

Question 86

Paresis refers to?

Answer 86

An inability to support weight or a deficiency in the ability to generate a gait.

Question 87

In neurologic patients, may paresis result from a lesion in the LMN or UMN?

Answer 87

In the lower motor neuron (LMN)/neuromuscular system, the upper motor neuron (UMN) system, or both.

Question 88

How do animals with “LMN paresis” manifes in their ability to support weight? Which limbs affected?

Answer 88

Animals with “LMN paresis” manifest a wide variation in their ability to support weight. Thoracic or pelvic limbs (or both sets of limbs with diffuse LMN disease) may be affected.

Question 89

How do animals with “UMN paresis” manifes in their ability to support weight? Which limbs affected?

Answer 89

Animals with “UMN paresis” also may have considerable variation in their ability to generate a gait. Depending on the location of a spinal cord or mid-to-caudal brainstem lesion, thoracic and/or pelvic limbs may be affected with UMN signs. Ambulatory pets with UMN paresis walk with a long-strided, spastic gait that is typically accompanied by general proprioceptive (GP) ataxia (Videos 258-2, 258-39). The latter occurs because the majority of the key UMN pathways (reticulospinal and rubrospinal tracts) that function in gait generation are anatomically adjacent to GP pathways (spinocerebellar tracts and conscious proprioceptive pathways). Spinal cord and mid to caudal brainstem lesions disrupt descending UMN pathways and ascending GP pathways, resulting in variable degrees of paresis and ataxia.

Question 90

Three clinical forms of ataxia (incoordination) exist: Which ones?

Answer 90

1) General proprioceptive (GP) ataxia, (2) vestibular ataxia, and (3) cerebellar ataxia.

Question 91

GP ataxia often occur simultaneously with .........paresis.

Answer 91

GP ataxia was previously reviewed in relation to UMN paresis because the two typically occur simultaneously. When ascending GP information fails to reach the brain, incoordination results. This incoordination may include crossing the limbs, scuffing or dragging of the digits, standing or landing on the dorsal aspect of the paws, and sometimes a delay in the swing phase of the gait. Together with the UMN signs, this produces a relatively characteristic gait that reflects both UMN paresis and GP ataxia (Videos 258-2, 258-39).

Question 92

Vestibular ataxia results from a loss of orientation of the head with respect to ..............................................

Answer 92

Vestibular ataxia results from a loss of orientation of the head with respect to the eyes, neck, limbs, and trunk. Pets with vestibular disease may lose their balance and have a tendency to drift, lean, or fall in one direction (Video 258-3). A head tilt and abnormal nystagmus commonly accompany vestibular ataxia (Video 258-28).

Question 93

With .........................vestibular lesions, pets maintain normal strength and proprioception, but with ...................vestibular lesions, UMN tetraparesis, and GP deficits typically are present (Video 258-34).

Answer 93

With peripheral vestibular lesions, pets maintain normal strength and proprioception, but with central vestibular lesions, UMN tetraparesis, and GP deficits typically are present (Video 258-34).

Question 94

Cerebellar ataxia is characterized by.........?

Answer 94

Cerebellar ataxia is characterized by a hypermetric gait with sudden bursts of motor activity (Video 258-4).

Question 95

Cerebellar hypermetria may be differentiated from a UMN gait by .........?

Answer 95

Cerebellar hypermetria may be differentiated from a UMN gait by a marked overflexion of the limbs on protraction; occasionally, this differentiation is challenging. Because of the close connection between cerebellum and vestibular systems, a head tilt, loss of balance, and abnormal nystagmus may be seen with cerebellar lesions (Video 258-35).

Question 96

Following the gait observation, postural reactions should be evaluated to identify subtle deficits of .......... and ...............

Answer 96

Following the gait observation, postural reactions should be evaluated to identify subtle deficits of strength and coordination.

Question 97

A pet's ability to perform postural reactions requires what?

Answer 97

That all major sensory (GP) and motor (UMN and LMN) components of the central nervous system (CNS) and peripheral nervous system (PNS) are intact.

Question 98

Can postural reactions be used solely to assess conscious proprioception?

Answer 98

Although many clinicians use postural reactions to assess conscious proprioception, this is a misnomer because all postural reactions rely on both the motor and proprioceptive systems. Furthermore, when assessing postural reactions, both the conscious and unconscious sensory pathways are tested; deficiencies in these two key components of GP cannot be separated practically.[1]

Question 99

Can interpreting postural reaction be of localizing value when performed without other components of the neurologic examination?

Answer 99

No. For example, a recumbent dog or cat with a severe and diffuse NMD or one with a severe cervical spinal cord lesion may have delayed (to absent) postural reactions in all four limbs. Close assessment of spinal reflexes, as well as muscle mass and tone, is necessary to differentiate between these two localizations. Another example would be that of a patient with unilateral postural reaction deficits, which has several possible localizations including a unilateral lesion of the prosencephalon, brainstem, or spinal cord. Unilateral prosencephalic lesions typically result in contralateral postural reaction deficits with a normal gait (and potentially accompanied by a contralateral menace deficit, contralateral sensory deficits, and changes in sensorium) (Video 258-33). Unilateral (caudal) brainstem or spinal cord lesions cause ipsilateral postural reaction deficits. Presence of cranial nerve abnormalities and/or changes in sensorium help differentiate between the two localizations and suggest the former.

Question 100

Se figur

Answer 100

Figure 258-1 Flowsheet for neuroanatomic diagnosis associated with postural reaction deficits. GP, General proprioceptive; LMN, upper motor neuron; UMN, upper motor neuron.

Question 101

In recumbent patients,................ testing may help to differentiate between UMN and LMN tetraparesis.

Answer 101

In recumbent patients, postural reaction testing may help to differentiate between UMN and LMN tetraparesis.

Question 102

A dog with “pure” LMN disease that maintains some voluntary movement should have relatively normal ................ (if most of the body weight is supported) This is because the GP system is unaffected by pure LMN disease. Conversely, a recumbent pet with a brainstem or spinal cord lesion will have delayed to absent .................. in all four limbs.

Answer 102

A dog with “pure” LMN disease that maintains some voluntary movement should have relatively normal postural reactions (if most of the body weight is supported) (Video 258-41). This is because the GP system is unaffected by pure LMN disease. Conversely, a recumbent pet with a brainstem or spinal cord lesion will have delayed to absent postural reactions in all four limbs.

Question 103

Postural Reaction Tests:

Answer 103

Hopping Paw replacement, tactile placing responses Extensor postural thrust Hemiwalking Wheelbarrowing

Question 104

Postural reaction test: Hopping: While supporting the pelvic limbs, the pet should be opped on one thoracic limb while the other thoracic limb is held off the ground. Hopping responses in the pelvic limbs should be evaluated similarly.Delayed hopping (symmetric or asymmetric) may occur with.........?

Answer 104

A motor (UMN or LMN) or sensory (GP) lesions. Commonly, both the UMN and GP systems (e.g., brainstem and spinal cord diseases) are affected simultaneously and the abnormal hopping response is a reflection of both (e.g., UMN/GP deficits). Lesions in the GP system or cerebellum may produce exaggerated responses (Video 258-6).

Question 105

Postural reaction test: Paw replacement, tactile placing responses. Paw replacement responses assess whether the dog or cat corrects its paw after it has been flexed so that weight is borne on its dorsal surface (Video 258-7). Is a delay in paw replacement response only associated with diminished CP (e.g., “CP deficit”)?

Answer 105

No, this is a misinterpretation of the test for three reasons: (1) A severely paretic animal with a pure LMN disease (e.g., myasthenia gravis) may have delayed (or even absent) paw replacement, despite having no lesion in the CP system (e.g., the dog may be too weak to return its paw to the normal anatomical position); (2) paw replacement responses do not isolate the CP pathways from the other afferent sensory pathways (e.g., spinocerebellar tracts) of the PNS and CNS; and (3) rarely (and inexplicably!) some pets without neurologic disease have delayed paw replacement responses.

Question 106

Postural reaction test: Tactile placing responses typically are performed in cats or small dogs. The pet should be supported off the ground and its thoracic limbs should be brought to the edge of a table so that the dorsal surface of the paws makes contact (Video 258-8). The pet should step quickly onto the table with the correct anatomic position. The test should be performed on the thoracic limbs simultaneously and individually. Why can it help to cover the pet´s eyes?

Answer 106

Because vision may compensate for sense of position when the GP system is abnormal.

Question 107

Postural reaction test: Hemiwalking. How is it performed?

Answer 107

On one side of the body, the thoracic and pelvic limbs should be held off the ground and the dog then forced to walk forward or to the side. Healthy dogs hop smoothly on both thoracic and pelvic limbs

Question 108

Postural reaction test: Wheelbarrowing. performed rarely, but it may be helpful in patients with subtle thoracic limb deficits. With this posture, vision is compromised and the animal relies heavily on ..... What is the result with severe lesions?.

Answer 108

With this posture, vision is compromised and the animal relies heavily on GP. With the head extended in normal position, dogs and cats should walk with symmetric movements of both thoracic limbs. With severe lesions, patients may carry their head flexed with the nose oriented close to the ground for support.

Question 109

Muscle mass and tone: Hypertonia or spasticity typically results from lesions in the ..........pathways (although it also may be seen with myotonic disorders). Describe how.

Answer 109

Hypertonia or spasticity typically results from lesions in the UMN pathways (although it also may be seen with myotonic disorders): The UMN normally influences activity of the LMN to facilitate voluntary motor activity and to maintain muscle tone, supporting the body against gravity. Lesions disrupting the UMN pathways may “release” the LMNs from inhibition, leading to overactivity of the facilitatory mechanism.

Question 110

Muscle mass and tone: Hypotonia is associated with ............ disease. Describe how.

Answer 110

Hypotonia is associated with LMN/neuromuscular disease. The functional integrity of the complete “LMN unit” (cell body, nerve root, peripheral nerve, neuromuscular junction, and muscle) is necessary to produce muscle cell contraction and to effectively maintain muscle tone. When the LMN unit is diseased, one consequence is a loss of muscle tone. With LMN disease, denervation also may lead to muscle cell degeneration and neurogenic atrophy may be appreciable.

Question 111

Tetraplegic dogs should be supported in a standing position, and the clinician should evaluate limb muscle tone and voluntary responses. Dogs with ............. disease often have hypertonic limbs while the trunk and limbs may feel spastic. Occasionally, the hypertonia associated with................. disease is so profound that the pet can maintain a standing position even when unsupported.

Answer 111

Tetraplegic dogs should be supported in a standing position, and the clinician should evaluate limb muscle tone and voluntary responses. Dogs with cervical spinal cord disease often have hypertonic limbs while the trunk and limbs may feel spastic. Occasionally, the hypertonia associated with cervical spinal cord disease is so profound that the pet can maintain a standing position even when unsupported.

Question 112

Tetraplegic dogs with diffuse .................typically are hypotonic and collapse when the clinician attempts to support them in a standing position.

Answer 112

Conversely, tetraplegic dogs with diffuse LMN/neuromuscular disease typically are hypotonic (or atonic) and collapse when the clinician attempts to support them in a standing position. It is critical to differentiate between UMN and LMN tetraplegia because the differential diagnoses are markedly different, as are diagnostics, management, and treatment recommendations.

Question 113

Spinal Reflexes: The most reliable reflexes?

Answer 113

The patellar and withdrawal-flexor reflexes

Question 114

Patellar reflex: The most reliable tendon reflex is the patellar reflex, which is mediated by the..............nerve through spinal cord segments ............

Answer 114

Patellar reflex: The most reliable tendon reflex is the patellar reflex, which is mediated by the femoral nerve through spinal cord segments L4-L7.

Question 115

Patellar reflex: Responses are typically graded as absent (0), hyporeflexive (+1), normal (+2), hyperreflexive (+3), or clonic (+4). An absent or hyporeflexive reflex occurs when there is a disease of a portion of the reflex arc (most commonly in the ..........). Hyperreflexia or clonus may be present in ...... diseases (Video 258-15).

Answer 115

Responses are typically graded as absent (0), hyporeflexive (+1), normal (+2), hyperreflexive (+3), or clonic (+4). An absent or hyporeflexive reflex occurs when there is a disease of a portion of the reflex arc (most commonly in the LMN unit). Hyperreflexia or clonus may be present in UMN diseases

Question 116

Biceps and Triceps Reflexes: The musculocutaneous nerve mediates the biceps reflex through spinal cord segments .......... The radial nerve mediates the triceps reflex through spinal cord segments .......

Answer 116

The musculocutaneous nerve mediates the biceps reflex through spinal cord segments C6-C8. The radial nerve mediates the triceps reflex through spinal cord segments C7-T2.

Question 117

Withdrawal-flexor reflexes assess the integrity of the thoracic and pelvic limb withdrawal reflex arcs. They are elicited by applying pressure to the base of the toenail with a firm, manual pinch or with hemostats. In the thoracic limb, the thoracodorsal, axillary, musculocutaneous, median, ulnar, and radial nerves are responsible for flexion of the shoulder, elbow, carpus, and digits. The nerves responsible for this reflex arise from spinal cord segments ........ Deficiencies in the thoracic limb withdrawal-flexor reflex suggest a ......... lesion (spinal cord segments, nerve roots, brachial plexus, peripheral nerves) or potentially a more diffuse .............. (the latter would be accompanied by reduced pelvic limb reflexes, reduced tone, and other neuromuscular signs). In the pelvic limb, the withdrawal-flexor reflex is mediated by the sciatic nerve through spinal cord segments ......... Lesions of the motor component of the ........... nerve (distal to the pelvis) may result in hypotonia, atrophy, and paralysis of the flexors of the stifle, tarsus, and digits, as well as of the extensors of the hip, tarsus, and digits. With sciatic lesions, pelvic limb withdrawal-flexor reflexes will be reduced to absent (Video 258-19).

Answer 117

Thoracic limb: The nerves responsible for this reflex arise from spinal cord segments C6-T2. Deficiencies in the thoracic limb withdrawal-flexor reflex suggest a C6-T2 lesion (spinal cord segments, nerve roots, brachial plexus, peripheral nerves) or potentially a more diffuse LMN/NMD (the latter would be accompanied by reduced pelvic limb reflexes, reduced tone, and other neuromuscular signs). In the pelvic limb, the withdrawal-flexor reflex is mediated by the sciatic nerve through spinal cord segments L6-S1. Lesions of the motor component of the sciatic nerve (distal to the pelvis) may result in hypotonia, atrophy, and paralysis of the flexors of the stifle, tarsus, and digits, as well as of the extensors of the hip, tarsus, and digits. With sciatic lesions, pelvic limb withdrawal-flexor reflexes will be reduced to absent (Video 258-19).

Question 118

Can dogs and cats walk with sciatic nerve paralysis?

Answer 118

Yes, but the tarsus is typically “dropped” on the affected side (tibial dysfunction) and the paw is often misplaced on the dorsal surface (peroneal dysfunction); however, the limb can support weight if the femoral nerve is intact.

Question 119

Crossed Extensor Reflex: Recumbent pets with lesions of the........ pathways may have a crossed extensor reflex when the withdrawal-flexor reflex is evaluated. Reflex extension may occur in the opposite limb to that being tested. Although typically abnormal and indicative of ......disease, normal dogs occasionally have crossed extensor reflexes.

Answer 119

UMN

Question 120

Perineal Reflex: The perineal reflex is mediated by branches of the sacral and caudal segments of the spinal cord through the ............. nerve.

Answer 120

Perineal Reflex: The perineal reflex is mediated by branches of the sacral and caudal segments of the spinal cord through the pudendal nerve.

Question 121

Cutaneous Trunci Reflex: This reflex is observed as a contraction of the cutaneous trunci muscle in response to mild stimulation of the dorsal skin of the trunk. It can be elicited from the thoracic and most of the lumbar region. Regional segmental ........nerves carry sensory impulses into the spinal cord, where they are relayed cranially to spinal cord segment .......... At this level, a synapse occurs on the LMNs of both lateral thoracic nerves that innervate the cutaneous trunci muscle. This reflex may require multiple attempts to elicit; rarely normal dogs and cats manifest no reflex. This reflex may be particularly useful in diagnosing the level of a transverse thoracolumbar .............lesion or for monitoring a progressive ............njury (e.g., ascending or descending myelomalacia). Typically, the reflex is preserved for one to two vertebral bodies caudal to the level of the spinal cord lesion.

Answer 121

Regional segmental spinal nerves carry sensory impulses into the spinal cord, where they are relayed cranially to spinal cord segment C8. At this level, a synapse occurs on the LMNs of both lateral thoracic nerves that innervate the cutaneous trunci muscle. This reflex may require multiple attempts to elicit; rarely normal dogs and cats manifest no reflex. This reflex may be particularly useful in diagnosing the level of a transverse thoracolumbar spinal cord lesion or for monitoring a progressive spinal cord injury (e.g., ascending or descending myelomalacia). Typically, the reflex is preserved for one to two vertebral bodies caudal to the level of the spinal cord lesion.

Question 122

Nociception (Pain Perception): In recumbent animals, the clinician may apply a noxious stimulus to a digit. This generates afferent impulses that enter the spinal cord via ...........nerves and associated dorsal nerve roots that are relayed to bilateral tracts in the lateral funiculi of the spinal cord. These tracts ascend the spinal cord and continue through the medulla, pons, and midbrain to specific nuclei in the .........for relay to somatic sensory areas of the ............. . A positive response is evidenced by vocalization, turning of the head, or dilation of the pupils when the impulses reach the thalamus or cerebrum.

Answer 122

In recumbent animals, the clinician may apply a noxious stimulus to a digit (Video 258-21). This generates afferent impulses that enter the spinal cord via peripheral nerves and associated dorsal nerve roots that are relayed to bilateral tracts in the lateral funiculi of the spinal cord. These tracts ascend the spinal cord and continue through the medulla, pons, and midbrain to specific nuclei in the thalamus for relay to somatic sensory areas of the cerebral cortex. A positive response is evidenced by vocalization, turning of the head, or dilation of the pupils when the impulses reach the thalamus or cerebrum.

Question 123

It is critical to differentiate nociception (Pain Perception) from the withdrawal component of the withdrawal-flexor reflex. Animals with transverse ...............lesions maintain the withdrawal reflex and this should not be mistaken for intact nociception.

Answer 123

It is critical to differentiate nociception (Pain Perception) from the withdrawal component of the withdrawal-flexor reflex. Animals with transverse spinal cord lesions maintain the withdrawal reflex and this should not be mistaken for intact nociception.

Question 124

Stepwise approach for evaluation of the cranial nerves by assessment of (1) vision and pupillary light responses (PLRs), (2) palpebral fissure and third eyelid symmetry, (3) eyeball position and movement, (4) vestibular function, (5) facial and trigeminal function, and (6) tongue and laryngeal-pharyngeal function. The clinical signs associated with cranial nerve dysfunction are summarized in Table 258-1.

Answer 124

Stepwise approach for evaluation of the cranial nerves by assessment of (1) vision and pupillary light responses (PLRs), (2) palpebral fissure and third eyelid symmetry, (3) eyeball position and movement, (4) vestibular function, (5) facial and trigeminal function, and (6) tongue and laryngeal-pharyngeal function. The clinical signs associated with cranial nerve dysfunction are summarized in Table 258-1.

Question 125

Vision and Pupillary Light Responses: which cranial nerves?

Answer 125

II, III, VII

Question 126

Which test is the most reliable test for vision assessment in animals?

Answer 126

The menace response. It is a learned response that may not be present until 10 to 12 weeks of age in puppies and kittens (tracking of moving objects may be helpful in such young animals).

Question 127

The menace response requires a functional .........., ..........tract (diencephalon), and optic radiation up to the ...........cortex, as well as the efferent pathway that includes the ..........neurons. A functional ............. also is required for the menace response.[1]

Answer 127

The menace response requires a functional optic nerve, optic tract (diencephalon), and optic radiation up to the occipital cortex, as well as the efferent pathway that includes the facial neurons. A functional cerebellum also is required for the menace response.

Question 128

The majority of the visual pathway caudal to the ............ is contralateral to the eye being tested.

Answer 128

The majority of the visual pathway caudal to the optic chiasm is contralateral to the eye being tested.

Question 129

A normal menace response is manifested as complete eyelid closure. Eyelid closure is dependent on normal ............innervation of the orbicularis oculi muscle. If the menace is absent or delayed, the eyelids must be assessed for their ability to close by eliciting the palpebral reflex. If facial paralysis is present, eyeball retraction, elevation of the third eyelid, and head retraction may help in the assessment of vision. Alternatively, the patient's ability to navigate an obstacle course can be evaluated.

Answer 129

Eyelid closure is dependent on normal facial nerve innervation of the orbicularis oculi muscle.

Question 130

Normal pets have rapid constriction of the pupil into which the light is directed (direct PLR) and the opposite pupil also should constrict (indirect or consensual PLR). The indirect response occurs because the majority of the .........nerve fibers cross at the ........... and, again at the level of the pretectal nucleus, stimulating the parasympathetic ..............................bilaterally.

Answer 130

Normal pets have rapid constriction of the pupil into which the light is directed (direct PLR) and the opposite pupil also should constrict (indirect or consensual PLR). The indirect response occurs because the majority of the optic nerve fibers cross at the optic chiasm and, again at the level of the pretectal nucleus, stimulating the parasympathetic oculomotor nuclei bilaterally.

Question 131

In addition to optic and oculomotor nerve lesions, there are several possible localizations for PLR deficits (Table 258-2). If a direct PLR is not elicited in one eye, the clinician should direct the light as close to that eye as possible and move the light to all aspects of the ocular fundus. If no response is present, the clinician should swing the light to the responsive pupil and the nonresponsive pupil should be assessed for constriction. If nonresponse is the result of an ocular or optic nerve lesion, it will ................ when light is directed into the contralateral eye (e.g., positive indirect PLR). Such testing may need to be repeated multiple times to differentiate between an ocular/optic and oculomotor nerve problem.

Answer 131

it will constrict

Question 132

The clinician should observe the palpebral fissures for size and symmetry. A reduced fissure size (ptosis) may be due to dysfunction of cranial nerve .....(...........) with secondary paresis of the levator palpebral superioris muscle, dysfunction of cranial nerve ......(...........nerve) with secondary atrophy of the masticatory muscles or sympathetic dysfunction with loss of orbitalis smooth muscle tone. Atrophy of the masticatory muscles or sympathetic dysfunction both may result in third eyelid ...........

Answer 132

A reduced fissure size (ptosis) may be due to dysfunction of cranial nerve III (oculomotor) with secondary paresis of the levator palpebral superioris muscle, dysfunction of cranial nerve V (trigeminal nerve) with secondary atrophy of the masticatory muscles, or sympathetic dysfunction with loss of orbitalis smooth muscle tone. Atrophy of the masticatory muscles or sympathetic dysfunction both may result in third eyelid elevation.

Question 133

Eyeball Position and Movement: which cranial nerves?

Answer 133

III, IV, VI, VIII

Question 134

While examining the head, the clinician should assess whether or not each eye is in a central position within the orbit, which requires normal function of the peripheral and central components of the vestibular system; cranial nerves .... (......)...... (......), and ......(...........); and the extraocular muscles that they innervate.

Answer 134

While examining the head, the clinician should assess whether or not each eye is in a central position within the orbit, which requires normal function of the peripheral and central components of the vestibular system; cranial nerves III (oculomotor), IV (trochlear), and VI (abducent); and the extraocular muscles that they innervate.

Question 135

Ventrolateral strabismus is associated with ..............nerve dysfunction, a medial strabismus with abducent nerve dysfunction, and eyeball extorsion with ...............nerve dysfunction.

Answer 135

Ventrolateral strabismus is associated with oculomotor nerve dysfunction, a medial strabismus with abducent nerve dysfunction, and eyeball extorsion with trochlear nerve dysfunction.

Question 136

Trochlear dysfunction in cats causes a lateral rotation of the dorsal aspect of the pupil, which cannot be recognized on external ocular examination in dogs. Why?

Answer 136

Because their pupils are round. In dogs, fundic examination is required and would show lateral deviation of the retinal vein.

Question 137

Vestibular Function: Physiologic nystagmus (oculocephalic or oculovestibular responses) is evaluated by moving the head in a horizontal plane from side to side. This stimulates cranial nerve ..........to relay impulses to the brainstem, on to the vestibular nuclei and the medial longitudinal fasciculus, and finally to abducent and oculomotor neurons for abduction and adduction of the eyeball, respectively.

Answer 137

This stimulates cranial nerve VIII to relay impulses to the brainstem, on to the vestibular nuclei and the medial longitudinal fasciculus, and finally to abducent and oculomotor neurons for abduction and adduction of the eyeball, respectively.

Question 138

Strabismus and nystagmus commonly are associated with dysfunction of the vestibular system. A positional, ventrolateral strabismus commonly is associated with ..................disease. Nystagmus is an involuntary oscillation of the eyeball. What is the difference between resting or spontaneous nystagmus?

Answer 138

Resting or spontaneous nystagmus is continual and observed when the head is in any position, whereas positional nystagmus is seen only when the head is held in certain positions. The latter often is seen in patients that have accommodated for lesions in the vestibular system. Utility of nystagmus for vestibular lesion localization is reviewed in the Neuroanatomic Diagnosis section of this chapter.

Question 139

The clinician should evaluate the palpebral reflex by gently touching the medial and lateral canthi of the eye. A normal response is an immediate, complete closure of the palpebral fissure. Sensory branches of the .............nerve mediate the afferent arm of the palpebral reflex, and the palpebral branch of the ............nerve mediates the efferent motor arm.

Answer 139

Sensory branches of the trigeminal nerve mediate the afferent arm of the palpebral reflex, and the palpebral branch of the facial nerve mediates the efferent motor arm.

Question 140

The clinician also should assess the symmetry of the face. A lip or ear droop or unilateral salivation suggests ........nerve dysfunction.

Answer 140

The clinician also should assess the symmetry of the face. A lip or ear droop (Video 258-29) or unilateral salivation suggests .........nerve dysfunction.

Question 141

To evaluate the mandibular branch of ...............nerve, the clinician should evaluate the temporalis and masseter muscles for size and symmetry.

Answer 141

To evaluate the mandibular branch of trigeminal nerve, the clinician should evaluate the temporalis and masseter muscles for size and symmetry. Mandibular paralysis may be accompanied by facial hypalgesia depending on the extent of involvement of the ophthalmic and maxillary sensory nerves.

Question 142

Trigeminal sensory function is most easily evaluated by......

Answer 142

By testing nasal sensation.

Question 143

What does the nasal sensation test evaluates? (The clinician should gently touch the medial aspect of the nasal mucosa with the tip of a pen or closed hemostats Normal patients will quickly pull their head away)

Answer 143

This test evaluates two neural pathways. First, it tests the ipsilateral branch of the ophthalmic nerve that innervates the nasal mucosa. It also tests the nociceptive pathways that project to the contralateral thalamus and somesthetic cerebral cortex. Therefore, nasal hypalgesia must be interpreted in light of the remainder of the neurological examination. It may indicate an ipsilateral trigeminal nerve lesion or a contralateral prosencephalic lesion

Question 144

Tongue and Laryngeal-Pharyngeal Function: which cranial nerves?

Answer 144

IX, X, XII

Question 145

The clinician may use the “gag-reflex” to simultaneously evaluate the ........, ........., and ............. cranial nerves. (Clinical utility of this test is limited due to the variability in normal responses). Dysphagia is a more reliable indicator of cranial nerve ........ and ..... dysfunction.

Answer 145

The clinician may use the “gag-reflex” to simultaneously evaluate the glossopharyngeal, vagus, and hypoglossal cranial nerves. (Clinical utility of this test is limited due to the variability in normal responses). Dysphagia is a more reliable indicator of cranial nerve IX and X dysfunction.

Question 146

After performing the complete neurologic examination, the clinician should attempt to make a neuroanatomic diagnosis to one of five major regions of the nervous system: Which ones?

Answer 146

(1) prosencephalon (cerebrum and/or thalamus); (2) mid to caudal brainstem (midbrain, medulla, pons); (3) cerebellum; (4) spinal cord; and (5) LMN/neuromuscular system. Neurologic signs associated with lesions in each of these regions are tabulated (Tables 258-3 through 258-6)

Question 147

The clinician initially should attempt to reconcile all neurologic deficits with a single lesion. If a single lesion cannot explain all signs, the neuroanatomic diagnosis is likely to be multifocal or diffuse (see later). After localizing the lesion to one of the five major regions of the CNS or ........, a more precise localization should be determined (e.g., side of lesion; specific anatomic segments affected: C1-C5, C6-T2, etc.).

Answer 147

CNS or PNS

Question 148

Prosencephalon: commonly used as an embryologic term to denote the area of brain composed of ...............?

Answer 148

telencephalon (cerebral hemisphere) and diencephalon (epithalamus, thalamus, and hypothalamus)

Question 149

Because of overlap in clinical signs associated with cerebral and thalamic disease, lesions affecting the two areas cannot be reliably differentiated. When neurologic signs suggest cerebrothalamic (forebrain) disease, a prosencephalic neuroanatomic diagnosis is made. Which abnormalities support a proencephalic neuroanatomic diagnosis?

Answer 149

Seizures, behavioral, and autonomic/endocrine changes support a prosencephalic neuroanatomic diagnosis, but these abnormalities rarely help to lateralize the lesion to one side of the cerebrum or thalamus. Animals with prosencephalic lesions commonly manifest visual, sensory (facial/nasal hypalgesia), and postural reaction deficits, all contralateral to the side of the lesion.

Question 150

Do animals with prosencephalic disease typically have a normal gait? Why?

Answer 150

Despite having postural reaction deficits (a true “CP” deficit), animals with prosencephalic disease typically have a normal gait (a transient gait deficit may be present with peracute lesions such as a cerebrovascular accident). The gait is normal with prosencephalic lesions because the critical UMNs responsible for gait generation in domestic species are spared because they are located more caudally in the midbrain, pons, and medulla.

Question 151

What is adversive (hemi-neglect or hemi-inattention) syndrome?

Answer 151

An unusual phenomenon that occurs sometimes with unilateral prosencephalic lesions. With this syndrome, the pet “ignores” all sensory input perceived from its environment that is contralateral to the prosencephalic lesion. The pet may circle propulsively or eat out of one side of a bowl (ipsilateral to the lesion). Table 258-3 summarizes the potential clinical signs associated with prosencephalic disease.

Question 152

Where is the brainstem located?

Answer 152

The brainstem is ventral to the two cerebral hemispheres and the cerebellum.

Question 153

Is the diencephalon part of the brainstem?

Answer 153

No, although anatomically the diencephalon is the rostral extent of the brainstem, it is considered part of the prosencephalic localization.

Question 154

A neuroanatomic diagnosis of “brainstem” is used to denote lesions that include......?

Answer 154

the midbrain, pons, and medulla oblongata.

Question 155

Functionally, the brainstem contains...?

Answer 155

The paired cranial nerve nuclei, the regulatory centers for consciousness (ARAS) and respiration, and descending motor and ascending sensory pathways. Thus, cranial nerve abnormalities, behavioral changes, loss of key autonomic functions, and a loss of strength and coordination may be present with brainstem disease.

Question 156

The brainstem connects the cerebral hemispheres to the spinal cord via ............... sensory (GP) and ..............motor pathways (UMNs).

Answer 156

The brainstem connects the cerebral hemispheres to the spinal cord via ascending sensory (GP) and descending motor pathways (UMNs).

Question 157

Similar to C..-C... spinal cord lesions, UMN tetraparesis (through tetraplegia) and GP deficits may accompany brainstem disease.

Answer 157

Similar to C1-C5 spinal cord lesions, UMN tetraparesis (through tetraplegia) and GP deficits may accompany brainstem disease.

Question 158

Because of the presence of vestibular nuclei in the .....and ........, vestibular ataxia may be present and superimposed upon GP ataxia

Answer 158

Because of the presence of vestibular nuclei in the pons and medulla, vestibular ataxia may be present and superimposed upon GP ataxia.

Question 159

Depending on the region of the mid to caudal brainstem affected, dysfunction of the cranial nerves ....-.....may be present.

Answer 159

Depending on the region of the mid to caudal brainstem affected, dysfunction of the cranial nerves III-XII may be present.

Question 160

The neurologic examination allows for assessment of the diverse motor and sensory functions of the cranial nerves (see Tables 258-1 and 258-4). Lesions affecting the cranial nerves in the caudal brainstem typically cause ........lateral postural reaction deficits because of their impact on the .......and GP systems. The presence of cranial nerve abnormalities and normal postural reactions suggests a ..............(cranial) neuropathy; however, an early or slowly compressive brainstem lesion cannot be excluded. If there is ambiguity in postural reaction testing, a neurodiagnostic workup should be considered.

Answer 160

Lesions affecting the cranial nerves in the caudal brainstem typically cause ipsilateral postural reaction deficits because of their impact on the UMN and GP systems. The presence of cranial nerve abnormalities and normal postural reactions suggests a peripheral (cranial) neuropathy; however, an early or slowly compressive brainstem lesion cannot be excluded. If there is ambiguity in postural reaction testing, a neurodiagnostic workup should be considered.

Question 161

Vestibular Disease: A head tilt, vestibular ataxia, nystagmus, and strabismus are seen commonly with vestibular disease. However, these neurologic signs rarely help the clinician to differentiate between central and peripheral vestibular disease. The key differentiating feature between central and peripheral vestibular disease is the presence or absence of .....? Describe the difference.

Answer 161

....the presence or absence of postural reaction deficits. With vestibular lesions involving the caudal brainstem, ipsilateral postural reaction deficits will be present due to involvement of the UMN/GP pathways (Video 258-34). Conversely, postural reactions will be normal with peripheral vestibular lesions because there is no involvement of the UMN/GP pathways.

Question 162

Lesions affecting the peripheral vestibular nerve result in a head tilt that is ............ (........ ear is ......... of the lesion) to the lesion; this is less predictable with brainstem lesions. Although most pets with central vestibular disease have an ..........head tilt, those with brainstem lesions involving the caudal ................ peduncle (or flocculonodular lobules of the cerebellum) may manifest a contralateral, or so-called paradoxical head tilt (Video 258-35).

Answer 162

Lesions affecting the peripheral vestibular nerve result in a head tilt that is ipsilateral (lower ear is on the side of the lesion) to the lesion; this is less predictable with brainstem lesions. Although most pets with central vestibular disease have an ipsilateral head tilt, those with brainstem lesions involving the caudal cerebellar peduncle (or flocculonodular lobules of the cerebellum) may manifest a contralateral, or so-called paradoxical head tilt (Video 258-35).

Question 163

Resting or positional nystagmus commonly accompany both central and peripheral vestibular disease. The direction of nystagmus is defined by the fast phase of the jerk of the eyeball. The plane of rotation may be rotatory, horizontal, or vertical. Typically, .........nystagmus is associated with central vestibular lesions (Video 258-34), whereas ..........or .........nystagmus may be present with either central or peripheral lesions.

Answer 163

Typically, vertical nystagmus is associated with central vestibular lesions, whereas rotatory or horizontal nystagmus may be present with either central or peripheral lesions.

Question 164

With peripheral vestibular lesions, the ............phase of the nystagmus is............ from the lesion; this is not reliable with central disease and may be in either direction. Moreover, the fast phase of nystagmus occasionally changes direction with brainstem lesions.

Answer 164

With peripheral vestibular lesions, the fast phase of the nystagmus is away from the lesion; this is not reliable with central disease and may be in either direction. Moreover, the fast phase of nystagmus occasionally changes direction with brainstem lesions.

Question 165

Additional cranial nerve deficits commonly accompany vestibular disorders. Which is the most common?

Answer 165

Facial nerve disorders are the most common and may be seen with both peripheral and central vestibular disease.

Question 166

Why does Horner's syndrome occasionally accompanies peripheral vestibular lesions?

Answer 166

Occasionally, Horner's syndrome accompanies peripheral vestibular lesions because the sympathetic fibers pass through the middle ear en route to the orbit.

Question 167

Rarely, a Horner's syndrome may be associated with a brainstem lesion because of involvement of the ............ (hypothalamo-tecto-tegmental) sympathetic pathway; this typically requires a severe brainstem lesion and usually the pet is tetraplegic with marked mentation changes. Sensorium is unaffected with...............vestibular lesions, whereas animals with ..........vestibular disease may be dull to comatose depending on the extent of involvement of the ARAS.

Answer 167

Rarely, a Horner's syndrome may be associated with a brainstem lesion because of involvement of the UMN (hypothalamo-tecto-tegmental) sympathetic pathway; this typically requires a severe brainstem lesion and usually the pet is tetraplegic with marked mentation changes. Sensorium is unaffected with peripheral vestibular lesions, whereas animals with central vestibular disease may be dull to comatose depending on the extent of involvement of the ARAS.

Question 168

The cerebellum functions as a regulator rather than a primary initiator of motor activity. It functions to coordinate movements in relation to the animal's posture providing synergy of muscular activity. Cerebellar disease produces what (characterized by?)? are voluntary movements elicited with normal strength?

Answer 168

Cerebellar disease produces a unique dysmetria characterized by an inability to regulate the rate, range, and force of a movement. Although a dog or cat with cerebellar disease may be incapacitated and unable to stand, voluntary movements should be elicited with normal strength.

Question 169

Clinical signs of a dog with cerebellar ataxia?

Answer 169

Ambulatory animals with cerebellar ataxia typically manifest “bursty” hypermetric movements in all ranges of motion. Voluntary movements typically are delayed in onset and, once initiated, exaggerated. When walking, the limbs usually are raised excessively and returned forcefully to the ground with each step. Muscle tone commonly is increased, and spinal reflexes may be normal to exaggerated. Although CP is unaffected with cerebellar disease, postural reactions are typically delayed and exaggerated. When the head of a pet with cerebellar disease is extended and then support is withdrawn suddenly, a rebound phenomenon may be present in which the head drops excessively in a ventral direction.

Question 170

Why may vestibular signs accompany cerebellar disease?

Answer 170

Because of the close connection to the vestibular system, a head tilt (usually paradoxical) and other vestibular signs may accompany cerebellar disease (Video 258-35).

Question 171

Commonly, a mild intention tremor of the head, neck, or eyes is present with cerebellar diseases (Video 258-37). This should not be confused with generalized, whole body tremors that are associated with diffuse CNS disorders. Finally, it is noteworthy that cerebellar disease may be associated with an ipsilateral (bilateral with diffuse cerebellar disease) menace deficit. Why?

Answer 171

Finally, it is noteworthy that cerebellar disease may be associated with an ipsilateral (bilateral with diffuse cerebellar disease) menace deficit. Although the cerebellum most commonly is affected diffusely (e.g., cerebellar hypoplasia or abiotrophy), occasionally unilateral or focal cerebellar lesions (cerebellar infarction or neoplasm) produce ipsilateral cerebellar signs.

Question 172

Definition of spinal cord segment? How many segments in dogs and cats?

Answer 172

A portion of the spinal cord, which gives rise to one pair of spinal nerves. There are 8 cervical, 13 thoracic, 7 lumbar, 3 sacral, and at least 2 caudal spinal cord segments in dogs and cats.

Question 173

Functionally, the spinal cord can be divided in four neuroanatomic regions: Which ones?

Answer 173

Functionally, the spinal cord can be divided in four neuroanatomic regions: cranial cervical (C1-C5), cervico-thoracic (C6-T2), thoracolumbar (T3-L3), and lumbosacral (L4-S3).

Question 174

The LMN cell bodies for the thoracic and pelvic limbs are located within the ............. matter of the cervico-thoracic (C6-T2) and lumbosacral (L4-S3) intumescences, respectively. The ascending (sensory) and descending (motor) pathways comprise the ......... matter of the spinal cord and are located more superficially.

Answer 174

The LMN cell bodies for the thoracic and pelvic limbs are located within the ventral gray matter of the cervico-thoracic (C6-T2) and lumbosacral (L4-S3) intumescences, respectively. The ascending (sensory) and descending (motor) pathways comprise the white matter of the spinal cord and are located more superficially.

Question 175

With rare exceptions, spinal cord lesions predictably result in a sequential loss of general .............., motor and bladder function, and .................. Recovery of function typically is in the reverse direction.

Answer 175

With rare exceptions, spinal cord lesions predictably result in a sequential loss of general proprioception, motor and bladder function, and nociception. Recovery of function typically is in the reverse direction.

Question 176

Spinal cord lesions typically produce a combination of UMN and GP deficits in which limbs?

Answer 176

Spinal cord lesions typically produce a combination of UMN and GP deficits in the limbs caudal to the level of the lesion.

Question 177

If the spinal cord lesion is in the cervical or lumbar intumescence, it will produce LMN signs where?

Answer 177

If the spinal cord lesion is in the cervical or lumbar intumescence, it will produce LMN signs in the corresponding thoracic or pelvic limbs.

Question 178

Spinal cord lesions may produce a combination of UMN and LMN signs where?

Answer 178

Spinal cord lesions may produce a combination of UMN and LMN signs in thoracic or pelvic limbs. For example, a herniated disk at the C6/C7 intervertebral disk space may cause a long-strided thoracic limb gait (UMN sign) but reduced thoracic limb withdrawal reflexes (LMN sign). Ambulatory patients with C6-T2 lesions typically have a disconnected, “two-engine” gait in which the thoracic limbs are “short and choppy” (LMN sign) and pelvic limbs are long strided (UMN sign) with GP ataxia[1]

Question 179

Establishing a neuroanatomic diagnosis to one of the .........spinal cord segments typically is straightforward and is based upon ...... potential combinations of normal, LMN, and UMN signs that may be present in the thoracic and pelvic limbs (Tables 258-7 through 258-10; see Figure 258-1 and Table 258-6).

Answer 179

Establishing a neuroanatomic diagnosis to one of the four spinal cord segments typically is straightforward and is based upon four potential combinations of normal, LMN, and UMN signs that may be present in the thoracic and pelvic limbs (Tables 258-7 through 258-10; see Figure 258-1 and Table 258-6). However, there are a few clinical scenarios that may create confusion with T3-L3 spinal cord disease.

Question 180

Lower Motor Neuron/Neuromuscular System: The LMN unit consists of?

Answer 180

The LMN unit consists of the nerve cell body in the ventral gray matter of the CNS, ventral nerve root, peripheral nerve, and muscle. Disease of any component of this unit will produce LMN signs.

Question 181

Normal strength depends not only on functional LMN unit, but also on effective neuromuscular transmission via ........................across the neuromuscular junction (NMJ).

Answer 181

Normal strength depends not only on functional LMN unit, but also on effective neuromuscular transmission via acetylcholine (Ach) across the neuromuscular junction (NMJ).

Question 182

Give ex of diseases affecting neuromuscular transmission; so called junctionopathies, that may produce LMN signs that are indistinguishable from neuropathies and myopathies.

Answer 182

e.g., myasthenia gravis, tick paralysis

Question 183

Can a neurologic examination most often confirm the exact component of the LMN unit that is affected?

Answer 183

Because NMDs may mimic one another, the neurologic examination rarely confirms the exact component of the LMN unit that is affected. The clinician may require ancillary tests (CK, AST, Tensilon testing, acetylcholine receptor antibody titer, electrodiagnostics, nerve and muscle biopsies) to further localize the problem to the nerve, muscle, or NMJ.

Question 184

Patients with polyneuropathies also may have delayed postural reactions. Why?

Answer 184

Patients with polyneuropathies also may have delayed postural reactions because of involvement of the sensory nerve fibers in the peripheral neuropathy.

Question 185

In some NMDs (e.g., polyneuropathies), involvement of the recurrent................ nerve may lead to a change in, or loss of, voice (dysphonia) and increased inspiratory noise (stridor).

Answer 185

laryngeal nerve.

Question 186

Peripheral Sensory Nerves: sensory afferent never fibers run where?

Answer 186

Sensory afferent nerve fibers run together with the LMNs within the peripheral nerves. Sensory axons have a cell body in the dorsal nerve root ganglion or in homologous ganglia of cranial nerves. A cutaneous region innervated by afferent nerve fibers from a single spinal or cranial nerve is called a dermatome.

Question 187

Are diseases exclusively affecting the sensory system common?

Answer 187

Diseases exclusively affecting the sensory system are rare (e.g., sensory neuropathies, ganglioradiculoneuritis) and they are characterized by variable sensory deficits ranging from hypalgesia to analgesia of various body parts.

Question 188

With various neurologic disorders, the deficits cannot be explained by a single lesion. For example, a Pug with necrotizing meningoencephalitis might manifest both ...........(seizures) and .............head tilt, vestibular ataxia) signs. In this scenario, a multifocal, intracranial localization is made.

Answer 188

With various neurologic disorders, the deficits cannot be explained by a single lesion. For example, a Pug with necrotizing meningoencephalitis might manifest both prosencephalic (seizures) and vestibular (head tilt, vestibular ataxia) signs. In this scenario, a multifocal, intracranial localization is made.

Question 189

Multifocal localizations are not analogous to disorders that affect the CNS diffusely, in which the majority of the neural axis is affected. The most common neurologic sign associated with diffuse CNS disease is?

Answer 189

a fine, whole body tremor. Whole body tremors should not be confused with the brief, intentional tremors of the head, neck, or torso that may be present with cerebellar disease.

Question 190

What is the Cushing's response?

Answer 190

With increasing intracranial pressure, generalized forebrain signs will develop, even if the inciting cause is a localized process such as neoplasia. As intracranial pressure increases, blood pressure will increase to maintain cerebral perfusion. This can sometimes result in a reflex increase in vagal tone and bradycardia (the Cushing's response). Vomiting may also occur. Continued increases in intracranial pressure will lead to herniation. Herniation is most commonly associated with forebrain lesions such as neoplasia or trauma.

Question 191

In the aspects of the neurologic examination: what is important in order to evaluate brain function?

Answer 191

(1) observation of behavior, posture, and gait; (2) postural reactions; and (3) cranial nerves.

Question 192

Why should the retina and optic nerve be examined when evaluating the nerve function?

Answer 192

Because the retina and optic nerve are basically extensions of the brain, the clinician should take advantage of the one place where they can look directly at the nervous system. Even if there are no neuro-ophthalmologic deficits, a disease process visualized in the fundus is likely to be the same process producing signs elsewhere in the nervous system.

Question 193

How can you differ between forebrain disease and brainstem disease when evaluating how the animal walks?

Answer 193

Forebrain disease tends to produce larger, wandering circles (sometimes the animal only makes a turn when it reaches a place where it cannot continue forward). Typically the circling will be toward the side of the forebrain lesion. Brainstem disease will more commonly produce tight circling or a tendency to lean against the wall with one side. The direction can be variable with brainstem lesions.

Question 194

What is a physiologic tremor?

Answer 194

Normally a subclinical tremor called the physiologic tremor occurs in all muscles. This is a high-frequency (6 to 12 Hz) tremor that disappears when the muscles are at rest. A variety of diseases can produce an enhanced physiologic tremor. Such a tremor is still a high-frequency tremor, and it tends to be most noticeable when the animal is standing quietly (postural tremor).

Question 195

What is an intention tremor?

Answer 195

Goal-directed movements activate an intention tremor. This is seen most clearly in the head when the animal attempts to eat or drink or otherwise tries to fix its attention on something. Such tremors are characteristic of cerebellar disease but may be seen in other conditions such as hypocalcemia. The tremors are coarser and slower (3 to 5 Hz) than physiologic tremors.

Question 196

Myoclonus refers to what?

Answer 196

Myoclonus refers to a brief contraction of a muscle, group of muscles, or occasionally the entire body. Although myoclonus can repeat rhythmically, it does not have the oscillating character of tremors. Instead a rapid jerk occurs, followed by a quiet period. Myoclonus is seen most commonly in dogs after distemper infection but can be seen in other conditions such as myoclonic epilepsy, toxicities such as lead poisoning, or metabolic encephalopathies.

Question 197

What is dyskinesia?

Answer 197

Dyskinesia is a general term to describe abnormal movement. It is important to recognize that in a quadruped, fine motor control is more important in the head and facial muscles than the limbs.

Question 198

With forebrain disease, the animal may tend to curl ...........side of the lesion as they orient toward that direction. With vestibular disease, the head tends to be rotated on the long axis so that one ear is lower than the other. The nose may be kept straightforward or sometimes turned away from the lower ear. Except for the paradoxical vestibular syndrome seen with cerebellar disease, the head tilt will be............the lesion.

Answer 198

With forebrain disease, the animal may tend to curl toward the side of the lesion as they orient toward that direction. With vestibular disease, the head tends to be rotated on the long axis so that one ear is lower than the other. The nose may be kept straightforward or sometimes turned away from the lower ear. Except for the paradoxical vestibular syndrome seen with cerebellar disease, the head tilt will be toward the lesion.

Question 199

What is dystonia?

Answer 199

Dystonia refers to a sustained abnormal contraction or posturing from basal ganglia disease.

Question 200

If the animal is stuporous or comatose, it may adopt abnormal postures that help to localize the lesion. A lesion affecting the midbrain will produce decerebrate ............ The neck is extended dorsally, and all four limbs are ............ Lesions of the cerebellum can sometimes produce a similar posture (decerebellate posture). The neck and thoracic limbs are extended, and the pelvic limbs are..............

Answer 200

A lesion affecting the midbrain will produce decerebrate rigidity. The neck is extended dorsally, and all four limbs are extended. Lesions of the cerebellum can sometimes produce a similar posture (decerebellate posture). The neck and thoracic limbs are extended, but the pelvic limbs are flexed.

Question 201

Evaluation of weakness: If an animal is weak from brain disease, it will be a UMN weakness. As a result, the limbs will tend to be ..........and the stride lengthened as opposed to ................... of the limbs seen with lower motor neuron (LMN) weakness.

Answer 201

If an animal is weak from brain disease, it will be a UMN weakness. As a result, the limbs will tend to be stiff and the stride lengthened as opposed to the short, shuffling stride and buckling of the limbs seen with lower motor neuron (LMN) weakness.

Question 202

Evaluation of weakness: An animal with cerebellar disease will have ...........strength with dysmetria.

Answer 202

An animal with cerebellar disease will have normal strength with dysmetria.

Question 203

Evaluation of weakness: An animal with ..................deficits tends to drag the toes and may stand with the foot knuckled under. It misplaces the feet and may cross over or step on itself, especially during tight circles.

Answer 203

An animal with proprioception deficits tends to drag the toes and may stand with the foot knuckled under. It misplaces the feet and may cross over or step on itself, especially during tight circles.

Question 204

The postural reactions are complex responses requiring integration of ...........information and coordination of ............responses at the brain level.

Answer 204

The postural reactions are complex responses requiring integration of sensory information and coordination of motor responses at the brain level (The entire circuit; sensory afferents, long tracts, higher integration, and motor efferents, are executed.
) Thus they are more involved than simple reflexes but still occur in direct response to a sensory stimulus, usually a perturbation of proprioception or balance. This makes them useful for evaluating brain function and spinal tracts.

Question 205

Does conscious proprioception such as evaluated by balancing the animal with one hand under the thorax or abdomen and knuckling one foot under so that the animal bears weight on the dorsum of the paw, qualify to be a postural reaction? Proprioception deficits with forebrain disease may not be as obvious as the deficits seen with spinal cord disease. An alternative method for assessing proprioceptive awareness is placing a sheet of paper under one foot and slowly pulling the paper laterally. An animal with proprioception deficits may allow the foot to slide far laterally, even though it may replace the foot when knuckled.

Answer 205

Although clinicians are mainly interested in the perception of the sensation, they are looking for a motor response (replacing the foot to a normal position). Thus this qualifies as a postural reaction. An alternative method for assessing proprioceptive awareness is placing a sheet of paper under one foot and slowly pulling the paper laterally. An animal with proprioception deficits may allow the foot to slide far laterally, even though it may replace the foot when knuckled.

Question 206

Proprioception deficits with ..........disease may not be as obvious as the deficits seen with ............. disease.

Answer 206

Proprioception deficits with forebrain disease may not be as obvious as the deficits seen with spinal cord disease.

Question 207

Postural reactions: Hopping also assesses .............., specifically where the foot is relative to the animal's center of gravity. The required motor response is more complex and thus allows the clinician to assess ........... and ................ A small animal may be held with all its weight on one paw, whereas in a larger animal, only one paw is lifted and the animal pivoted. As the animal moves laterally, it should begin to hop to the side before its center of gravity passes over the paw. .................deficits result in a delayed or absent initiation of the response. ............... disease would result in an exaggerated movement, whereas .....................lesions would result in a weak or absent response.

Answer 207

Hopping also assesses proprioception, specifically where the foot is relative to the animal's center of gravity. The required motor response is more complex and thus allows the clinician to assess motor function and sensory perception. A small animal may be held with all its weight on one paw, whereas in a larger animal, only one paw is lifted and the animal pivoted. As the animal moves laterally, it should begin to hop to the side before its center of gravity passes over the paw. Proprioception deficits result in a delayed or absent initiation of the response. Cerebellar disease would result in an exaggerated movement, whereas UMN lesions would result in a weak or absent response.

Question 208

Postural reactions: Hemistanding and hemiwalking are good for comparing strength and coordination on one side of the body versus the other. First, both legs on one side are lifted off the ground so that the animal has to support all of its weight on one side and strength can be assessed. Then the animal is moved laterally so that it has to walk sideways on one side. This is a sensitive test of the ability of the ................lateral forebrain to control those limbs.

Answer 208

This is a sensitive test of the ability of the contralateral forebrain to control those limbs.

Question 209

Postural reaction: Visual placing assesses the animal's ability to use a ......... stimulus to coordinate a ...........response.

Answer 209

Visual placing assesses the animal's ability to use a visual stimulus to coordinate a motor response. As with proprioceptive positioning, the clinician is mainly interested in the sensory perception, in this case, vision. The normal response is to reach out and place one or both thoracic paws on the table.

Question 210

Postural reaction: Tactile placing can be used to evaluate light touch perception of the thoracic limbs. The procedure is like visual placing, except the animal is blindfolded and the dorsum of the paw lightly touched against the table. Normal response?

Answer 210

The normal response when the paws touch the ground is an extension of the limb and a shuffle to get the feet underneath the body.

Question 211

Postural reaction: The righting response. In this case the main sensory modality evaluated is the...........

Answer 211

The main sensory modality evaluated is the vestibular system. Proprioception and vision can also play a role, particularly in animals with vestibular deficits.

Question 212

The righting response: Blindfolding the animal to remove visual compensation will exacerbate a vestibular deficit. Suspending the animal by the pelvis with the head down removes most proprioception clues, and the clinician can assess the animal's ability to orient to gravity. Normal reaction?

Answer 212

A normal animal will attempt to keep the head upright, whereas an animal with vestibular deficits may curl or move the head regardless of orientation to gravity. Alternatively the animal can be placed in lateral recumbency and allowed to right itself. A normal response would be a rostral-caudal righting, whereby the animal brings up the head, then neck, then shoulders, and sometimes also the pelvis.

Question 213

Cranial Nerves: Because the cranial nerves originate in the brain, careful evaluation assesses the function of not only the nerve itself but also?

Answer 213

The associated brain areas

Question 214

Although there can be UMN-type deficiencies in cranial nerves (just as for spinal reflexes), these are difficult to detect in animals. Thus with a few exceptions, a deficiency in a cranial nerve reflects damage either to ............ or the .............. where the nucleus resides.

Answer 214

........a deficiency in a cranial nerve reflects damage either to the nerve itself or the brain area where the nucleus resides.

Question 215

Cranial nerve deficits will generally be ipsilateral to the lesion with the exception of the .............and .........nerves, which may be contralateral.

Answer 215

Cranial nerve deficits will generally be ipsilateral to the lesion with the exception of the optic (II) and trochlear (IV) nerves, which may be contralateral.

Question 216

Forebrain lesions may produce a loss of response to sensory information originating from the .............side.

Answer 216

Forebrain lesions may produce a loss of response to sensory information originating from the contralateral side.

Question 217

The ........is the only sensory nerve that does not relay through the thalamus.

Answer 217

The olfactory nerve (I) is the only sensory nerve that does not relay through the thalamus. Instead, it projects to the pyriform cortex and limbic areas such as the septal nuclei and amygdala, areas important in emotional responses. This may explain why odors can have a profound emotional effect.

Question 218

The optic nerve (II) is evaluated by assessing ........and........

Answer 218

Vision and the pupils. Vision refers to the conscious perception of a visual stimulus, so clinicians rely on observing a behavioral response to determine if the animal has perceived the stimulus.

Question 219

The decussation of the optic nerves ensures that all visual information from one side goes to the ...............

Answer 219

The decussation of the optic nerves ensures that all visual information from one side goes to the contralateral visual cortex (Figure 259-6).

Question 220

The most effective way to evaluate vision?

Answer 220

The most effective way to evaluate vision is by tossing a cotton ball from behind, toward one side or the other, and observing whether the animal tracks the cotton ball (Figure 259-7). By avoiding the area directly in front of the animal where stereoscopic vision occurs, it is easier to differentiate loss in one visual field. The cotton ball will not create any noise and will typically surprise the animal enough to elicit some response. The ability of the animal to negotiate obstacles in the examination room such as the examination table or a chair can also evaluate vision. One eye can be covered to detect unilateral deficits. If the animal appears blind, the room can be darkened to dilate the pupils and the door opened to a bright hallway. If it cannot perceive the doorway, then it is unlikely that the animal has any functional vision. If the animal is small enough to be picked up easily, visual placing can be used to assess vision.

Question 221

Is the menace response acquired? Can it localize a lesion?

Answer 221

The menace response is an acquired and complex response, not a simple reflex. It is one of the last cranial nerve responses to develop and may not be apparent until the animal is 12 weeks of age. Because it is a complex pathway, a menace loss does not precisely localize a lesion without clues from the rest of the examination.

Question 222

The .......... provides the sensory afferents for the pupillary light reflex (PLR).

Answer 222

The optic nerve (II) provides the sensory afferents for the pupillary light reflex (PLR).

Question 223

The optic nerve (II) provides the sensory afferents for the pupillary light reflex (PLR). The sensory afferents for the pupillary light reflex synapse in nuclei in the midbrain and control the .............. constriction of the pupil via the ................ Crossover in the ...............and the midbrain ensures that both pupils respond together.

Answer 223

The sensory afferents for the pupillary light reflex synapse in nuclei in the midbrain and control the parasympathetic constriction of the pupil via the oculomotor nerve (III). crossover in the optic chiasm and the midbrain ensures that both pupils respond together. (Figure 259-8).

Question 224

PLR: A light in one eye produces a constriction of the ........... eye (direct response) and the ............eye (indirect or consensual response). A unilateral lesion of the retina or the optic nerve distal to the optic chiasm will produce blindness ..................Shining a light in the affected eye will .....................a response in ...............

Answer 224

A light in one eye produces a constriction of the ipsilateral eye (direct response) and the contralateral eye (indirect or consensual response). A unilateral lesion of the retina or the optic nerve distal to the optic chiasm will produce blindness in that eye; thus if the other eye is blindfolded, the animal will have no vision. Shining a light in the affected eye will not produce a response in either pupil.

Question 225

A unilateral lesion of the retina or the optic nerve distal to the optic chiasm will produce blindness in that eye. How will the pupil size and consensual response in the affected eye be?

Answer 225

Because the consensual innervation from the unaffected eye would be intact, pupil size and consensual response in the affected eye would be normal.

Question 226

How would the pupil size and consensual response be with bilateral disease/blindness?

Answer 226

Both pupils would be dilated and completely unresponsive to light in either eye

Question 227

A lesion affecting the parasympathetic third nerve, either in the brainstem or peripherally, would cause a ..............pupil in the ..................... eye that did not respond to light in ................ eye. Vision in that eye, however, would be normal, and shining a light in the affected eye would still elicit ................ of the contralateral pupil (consensual response).

Answer 227

A lesion affecting the parasympathetic third nerve, either in the brainstem or peripherally, would cause a dilated pupil in the ipsilateral eye that did not respond to light in either eye. Vision in that eye, however, would be normal, and shining a light in the affected eye would still elicit constriction of the contralateral pupil (consensual response). These fibers synapse in nuclei in the midbrain and control the parasympathetic constriction of the pupil via the oculomotor nerve (III). In mammals, crossover in the optic chiasm and the midbrain ensures that both pupils respond together (Figure 259-8). Thus a light in one eye produces a constriction of the ipsilateral eye (direct response) and the contralateral eye (indirect or consensual response).

Question 228

A unilateral lesion of the retina or the optic nerve distal to the optic chiasm will produce blindness in that eye; thus if the other eye is blindfolded, the animal will have no vision. Shining a light in the affected eye will................a response in ............... pupil. Because the consensual innervation from the unaffected eye would be intact, pupil size and consensual response in the affected eye would be normal.

Answer 228

A unilateral lesion of the retina or the optic nerve distal to the optic chiasm will produce blindness in that eye; thus if the other eye is blindfolded, the animal will have no vision. Shining a light in the affected eye will not produce a response in either pupil. Because the consensual innervation from the unaffected eye would be intact, pupil size and consensual response in the affected eye would be normal.

Question 229

With bilateral lesion of the retina or the optic nerve distal to the optic chiasm; what will happen to the pupils?

Answer 229

With bilateral disease, both pupils would be dilated and completely unresponsive to light in either eye.

Question 230

A lesion affecting the parasympathetic third nerve, either in the brainstem or peripherally, would cause?

Answer 230

....a dilated pupil in the ipsilateral eye that did not respond to light in either eye. Vision in that eye, however, would be normal, and shining a light in the affected eye would still elicit constriction of the contralateral pupil (consensual response).

Question 231

Does the sympathetic or parasympathetic innervation control the pupil dilation?

Answer 231

The sympathetic innervation of the pupil controls dilation.

Question 232

Why can't the pupil dilate normally in darkness in animals affected by Horner's syndrome?

Answer 232

The first sympathetic fibers to leave the spinal cord at the T1-T2 cord segments run cranially in the vagosympathetic trunk to synapse in the cranial cervical ganglia at the base of the skull. From there, the postganglionic fibers course through the middle ear and into the calvarium, where they join with the ophthalmic branch of the trigeminal nerve and project through the retrobulbar area to innervate the eye. A lesion anywhere along this path can produce the classic signs of Horner's syndrome. The pupil cannot dilate normally in darkness but constricts normally in response to light, so the anisocoria will be most evident in dim lighting.

Question 233

Loss of sympathetic innervation to other structures around the eye would produce

Answer 233

enophthalmos, ptosis, elevated third eyelid, and vasodilation.

Question 234

Eye movements are controlled by which nerves? Damage to one of these nerves results in?

Answer 234

The oculomotor (III), trochlear (IV), and abducens (VI) nerves. Results in deviation of the eye (strabismus) because the muscles innervated by the functioning nerves pull the eye away from the denervated muscles. Thus with loss of the oculomotor nerve (III), a ventrolateral strabismus occurs. Trochlear nerve (IV) loss results in an outward rotation of the top of the eye. In an animal with a round pupil like the dog, this can be detected by the position of the vessels in the fundus. The trochlear nerve (IV), like the oculomotor nerve (III), originates in the midbrain, but it is the only cranial nerve to completely decussate. The abducens nerve (VI) originates near the vestibular nucleus in the medulla. Loss of this nerve results in a medial strabismus. The abducens nerve (VI) also innervates the retractor bulbi muscle.

Question 235

The doll's eye reflex (physiologic nystagmus or oculocephalic reflex) can be used to induce eye movements, and thus evaluate ........system, and the innervation of the ..........muscles.

Answer 235

........the vestibular system, and the innervation of the extraocular muscles. The vestibular apparatus detects movement of the head. The vestibular nuclei feed information about the direction and speed of movement to the third, fourth, and sixth nerve nuclei, which move the eyes in the opposite direction at exactly the same speed. This allows the animal to maintain a fixed image on the retina even when the head is moving. Once the eyes have reached the limit of their range of movement in that direction, a center in the pons takes over to quickly flick the eyes back in the direction of the head movement, and the process begins again. Clinicians can observe this physiologic nystagmus by rotating the head to one side at a moderate speed and observing the eye movements.

Question 236

Facial sensation is carried by the three branches of the ........nerve. Which branches?

Answer 236

Trigeminal nerve (V). -The ophthalmic branch innervates the skin medial to the eye and the cornea (the palpebral or corneal reflex, respectively: if sensation is present and the motor innervation of the eyelid muscles by the facial nerve (VII) is intact). Because the sympathetic fibers to the eye travel with the ophthalmic branch, Horner's syndrome can accompany the sensory loss. -The maxillary branch innervates the skin of the side of the face. The mandibular branch carries sensation for the skin of the chin and just ventral and rostral to the ear. The muscles of mastication are innervated by the motor portion of the mandibular branch of the trigeminal nerve (V).

Question 237

Bilateral trigeminal paralysis will result in?

Answer 237

Bilateral trigeminal paralysis will result in a dropped jaw and an inability to prehend food. The animal will be able to swallow normally when food is placed into the back of the mouth because pharyngeal function is normal. With unilateral paralysis, the animal will be able to eat normally, and the only sign will be atrophy of the temporalis and masseter muscle on the ipsilateral side.

Question 238

Facial nerve (VII) palsy results in?

Answer 238

Loss of function of the small muscles of the face. The most obvious sign will be an inability to blink the eye on the ipsilateral side, either spontaneously, in the palpebral and corneal reflex, or in the menace response. The lip and cheek may sag, and food may become lodged in the cheek. The nostrils will not flair with respiration, and cats will not be able to move their whiskers forward. The animal will not be able to lay the ear back, and in droop-eared dogs the ear will sag further. With chronic denervation, the muscles may contract, producing a grimacing facial expression.

Question 239

Why can dry eye accompany the loss of blinking?

Answer 239

Because the parasympathetic innervation of the lacrimal glands is also carried by the facial nerve, a dry eye may accompany the loss of blinking, predisposing the eye to exposure keratitis. Tear production can be evaluated by the Schirmer tear test.

Question 240

The ....... nerve also conveys taste sensation from the rostral two thirds of the tongue. Taste from the caudal one third of the tongue is carried in the ...........nerve but is more difficult to evaluate in animals.

Answer 240

Taste from the caudal one third of the tongue is carried in the glossopharyngeal nerve but is more difficult to evaluate in animals.

Question 241

The vestibular portion of the eighth cranial nerve transmits information about the position of the head relative to gravity and head movement from the inner ear. The vestibular nuclei use this information to control........... ......... and maintain ............

Answer 241

The vestibular portion of the eighth cranial nerve transmits information about the position of the head relative to gravity and head movement from the inner ear. The vestibular nuclei use this information to control eye movements (discussed previously) and maintain balance.

Question 242

Acute unilateral lesions affecting the vestibular apparatus will cause profound disruption of balance. It will lean and may even roll .................. the side of the lesion. There will be a head tilt ............the affected side, sometimes dramatically. If able to walk, affected animals may circle or lean against a wall for balance.

Answer 242

Acute unilateral lesions affecting the vestibular apparatus will cause profound disruption of balance. It will lean and may even roll toward the side of the lesion. There will be a head tilt toward the affected side, sometimes dramatically. If able to walk, affected animals may circle or lean against a wall for balance.

Question 243

Spontaneous nystagmus occurs because?

Answer 243

Spontaneous nystagmus occurs because the imbalanced vestibular input creates a perception that the animal is spinning when it is not.

Question 244

With peripheral vestibular disease, the nystagmus is...................with the fast phase .............from the lesion. What is positional strabismus?

Answer 244

With peripheral vestibular disease, the nystagmus may be horizontal or rotary with the fast phase away from the lesion. With time, the animal can compensate even if vestibular function does not return on the affected side. With time, a residual head tilt may be the only sign that the vestibular system has not recovered completely. When the head is tilted, the eye position appears normal. If the clinician straightens the animal's head, the eye ipsilateral to the lesion will deviate ventrally. This is referred to as a positional strabismus.

Question 245

The auditory portion of the ................. cranial nerve mediates hearing.

Answer 245

The auditory portion of the eighth cranial nerve mediates hearing. Like vision, hearing refers to the conscious perception of a sensory stimulus and is assessed by observing the response to a noise such as clapping or a squeaky toy.

Question 246

Swallowing entails coordination of the tongue, pharynx, larynx, and esophagus. The ................and cranial branches of the ...................... innervate the pharyngeal muscles and carry sensory information from the caudal tongue and pharynx.

Answer 246

Swallowing entails coordination of the tongue, pharynx, larynx, and esophagus. The glossopharyngeal nerve (IX) and cranial branches of the vagus nerve (X) innervate the pharyngeal muscles and carry sensory information from the caudal tongue and pharynx. Damage to these nerves would affect the ability to swallow but not the ability to prehend food. Clinicians can use the gag reflex to assess pharyngeal function by placing the finger or a tongue depressor on the caudal aspect of the tongue. A normal animal will gag and swallow, whereas an animal with glossopharyngeal paralysis will not respond. An animal with unilateral damage may still be able to swallow, but it will choke, gag, or lose food through the nostrils. Regurgitation of swallowed food occurs with disorders of esophageal motility.

Question 247

Major nerve of the esophagus?

Answer 247

The vagus nerve (X) is the major nerve of the esophagus.

Question 248

The larynx is innervated primarily by the ...........through the cranial and recurrent laryngeal nerves. Unilateral paralysis produces laryngeal hemiplegia and inspiratory stridor.

Answer 248

The larynx is also innervated primarily by the vagus nerve (X) through the cranial and recurrent laryngeal nerves. Unilateral paralysis produces laryngeal hemiplegia and inspiratory stridor.

Question 249

The .....................may contribute to some of the laryngeal and pharyngeal muscles, but it primarily innervates the trapezius, brachiocephalicus, and sternocephalicus. Denervation of these muscles is difficult to detect clinically.

Answer 249

The spinal accessory nerve (XI) may contribute to some of the laryngeal and pharyngeal muscles, but it primarily innervates the trapezius, brachiocephalicus, and sternocephalicus. Denervation of these muscles is difficult to detect clinically.

Question 250

The intrinsic and extrinsic muscles of the tongue are supplied by the........................ Unilateral damage will denervate the ipsilateral muscles and result in deviation of the tongue (Figure 259-9). Bilateral lesions abolish tongue movement, preventing normal prehension and ............

Answer 250

The intrinsic and extrinsic muscles of the tongue are supplied by the hypoglossal nerve (XII). Unilateral damage will denervate the ipsilateral muscles and result in deviation of the tongue (Figure 259-9). Bilateral lesions abolish tongue movement, preventing normal prehension and swallowing.

Question 251

Once a neurologic examination has been performed, that information is synthesized to localize the lesion. For localization purposes, the brain can be divided into four broad areas: Which ones?

Answer 251

(1) the forebrain (cerebrum and diencephalon) (2) the midbrain (3) the pons and medulla (4) the cerebellum

Question 252

If a single lesion cannot explain some signs, multifocal disease is suspected. Can a single lesion explain an animal that has both seizures and unilateral facial palsy?

Answer 252

No! A single lesion cannot explain an animal that has both seizures (cerebral cortex) and unilateral facial palsy (medulla or facial nerve)?

Question 253

The cerebellum receives input from ............... and sensory feedback from ................ and the ................ It uses this information to coordinate movement and help maintain balance. The connections to and from the cerebellum via the cerebellar peduncles form a large part of the ...........

Answer 253

The cerebellum receives input from higher motor command centers and sensory feedback from proprioceptive afferents and the vestibular system. It uses this information to coordinate movement and help maintain balance. The connections to and from the cerebellum via the cerebellar peduncles form a large part of the pons.

Question 254

A disease affecting the cerebellum or its peduncles will produce ........................, ..............., and.................

Answer 254

A disease affecting the cerebellum or its peduncles will produce dysmetria, tremors, and vestibular signs. The tremors of cerebellar disease are coarse tremors that disappear at rest. In acute cerebellar disease the tremors can be almost constant and the most dramatic manifestation of dysfunction. In more chronic disease such as congenital cerebellar deficits, the tremors may be more subtle and only noticeable when the animal attempts to make a directed movement such as eating (intention tremors).

Question 255

The cerebellum works intimately with the .............. system to control balance and eye movements.

Answer 255

The cerebellum works intimately with the vestibular system to control balance and eye movements.

Question 256

Lateralized lesions in the cerebellum; such as in one cerebellar peduncle can produce head tilt, imbalance, and ................nystagmus similar to a peripheral vestibular lesion.

Answer 256

Lateralized lesions such as in one cerebellar peduncle can produce head tilt, imbalance, and horizontal or rotary nystagmus similar to a peripheral vestibular lesion.

Question 257

With cerebellar disease, the direction of the head tilt (..............from the lesion) and nystagmus (fast phase .............the lesion) are the opposite direction as in peripheral vestibular disease. This is referred to as paradoxical vestibular syndrome. With more diffuse disease of the cerebellum, a ................. nystagmus can be present as in central vestibular disease.

Answer 257

With cerebellar disease, the direction of the head tilt (away from the lesion) and nystagmus (fast phase toward the lesion) are the opposite direction as in peripheral vestibular disease. This is referred to as paradoxical vestibular syndrome. With more diffuse disease of the cerebellum, a vertical nystagmus can be present as in central vestibular disease. In either case the animal may also lose its balance, especially in response to quick movements such as shaking the head or sudden turns. Severe cerebellar lesions can produce decerebellate posturing, extension of neck, and thoracic limbs with flexion of the pelvic limbs. Because the menace response is a learned motor response and the cerebellum plays an important role in motor learning, animals with cerebellar disease may lose the menace response.

Question 258

The most caudal portions of the brainstem?

Answer 258

The pons and medulla are the most caudal portions of the brainstem (Figure 259-12). The sensory and motor tracts of the spinal cord traverse these areas as well; thus lesions in this area can produce deficits in these long tracts similar to cervical spinal cord disease.

Question 259

Why would an animal with a lower brainstem lesion producing complete paralysis would die from respiratory compromise?

Answer 259

Because the respiratory centers reside in the medulla, an animal with a lower brainstem lesion producing complete paralysis would die from respiratory compromise. In addition to respiration, other autonomic centers reside in the brainstem, although clinical signs associated with their malfunction may not be as readily apparent.

Question 260

Lesion of the pons and medulla can affect cranial nerves....... to .......

Answer 260

Lesion of the pons and medulla can affect cranial nerves V to XII

Question 261

..................deficits are the signs that point most directly to a brainstem lesion. In isolation, such deficits could reflect a peripheral nerve lesion or small focal brainstem disease. Multiple nerve deficits or concurrent long tract signs (e.g., hemiparesis, proprioception deficits) point toward ............... involvement. Cranial nerves ......to ..... arise from the pons and medulla. They all remain ipsilateral, and thus a lateralized deficit will be on the side of the lesion.

Answer 261

Cranial nerve deficits are the signs that point most directly to a brainstem lesion. In isolation, such deficits could reflect a peripheral nerve lesion or small focal brainstem disease. Multiple nerve deficits or concurrent long tract signs (e.g., hemiparesis, proprioception deficits) point toward brainstem involvement. Cranial nerves V to XII arise from the pons and medulla. They all remain ipsilateral, and thus a lateralized deficit will be on the side of the lesion.

Question 262

The facial nerve (VII), vestibulocochlear nerve (VIII), and nerves controlling the pharynx, larynx, and tongue (...........) run laterally from the brainstem out their respective foramina. The trigeminal nerve (V) originates from the pons in close proximity to these nerves but runs rostrally to exit ................ The abducens nerve (VI) also runs rostrally from the medulla to innervate the lateral rectus and retractor bulbi muscles. A lesion produces a medial strabismus.

Answer 262

The facial nerve (VII), vestibulocochlear nerve (VIII), and nerves controlling the pharynx, larynx, and tongue (IX, X, XII) run laterally from the brainstem out their respective foramina. The trigeminal nerve (V) originates from the pons in close proximity to these nerves but runs rostrally to exit retrobulbar. The abducens nerve (VI) also runs rostrally from the medulla to innervate the lateral rectus and retractor bulbi muscles. A lesion produces a medial strabismus.

Question 263

In addition to the nuclei of cranial nerves......and ......., the midbrain contains important motor nuclei and serves a major role in regulation of consciousness

Answer 263

In addition to the nuclei of cranial nerves III and IV, the midbrain contains important motor nuclei and serves a major role in regulation of consciousness. Midbrain lesions can produce decerebrate rigidity, a posture with dorsal extension of the neck and extension of the limbs.

Question 264

Why can an animal continue to breathe even if completely paralyzed from a midbrain lesion?

Answer 264

Because the respiratory centers reside more caudally in the medulla, the animal can continue to breathe even if completely paralyzed from a midbrain lesion.

Question 265

Conscious proprioception tracts must also course through the ...............on their way toward higher centers. Thus deficits in postural reactions may be apparent with a ................... lesion even if the animal is still capable of voluntary movements.

Answer 265

Conscious proprioception tracts must also course through the midbrain on their way toward higher centers. Thus deficits in postural reactions may be apparent with a midbrain lesion even if the animal is still capable of voluntary movements.

Question 266

Lesions of the midbrain affect cranial nerves ......and .......

Answer 266

Lesions of the midbrain affect cranial nerves III and IV

Question 267

Lesions below the midbrain may produce complete ........ and ............. compromise but may not directly alter consciousness or behavior. The midbrain marks the beginning of the .................. (RAS), a group of loosely defined areas that project from the cranial pons, midbrain, and hypothalamus to the cerebral cortex and regulate consciousness and goal-directed behavior. Lesions of the midbrain will affect these functions (see following discussion).

Answer 267

Lesions below the midbrain may produce complete paralysis and respiratory compromise but may not directly alter consciousness or behavior. The midbrain marks the beginning of the reticular activating system (RAS), a group of loosely defined areas that project from the cranial pons, midbrain, and hypothalamus to the cerebral cortex and regulate consciousness and goal-directed behavior. Lesions of the midbrain will affect these functions (see following discussion).

Question 268

The trochlear nerve (IV) innervates the dorsal oblique muscle. Deficits result in.....?

Answer 268

.......outward rotation of the eye and, because the trochlear nerve is the only cranial nerve to completely decussate; a midbrain lesion will produce strabismus in the contralateral eye.

Question 269

In animals with round pupils such as the dog, strabismus can only be detected by? Why is this not a problem in general?

Answer 269

In animals with round pupils such as the dog, strabismus can only be detected by looking at the orientation of the vessels in the fundus. Because the trochlear nerve will seldom be damaged without affecting other cranial nerves, this is usually not an issue. The oculomotor nerve (III) innervates the remaining extraocular muscles. Damage results in ventrolateral strabismus and loss of the normal doll's eye response in the ipsilateral eye. The third nerve also contains the parasympathetic fibers to the pupil. Damage to these fibers will produce mydriasis and loss of the PLR, although vision is unaffected.

Question 270

The forebrain encompasses ...? (4)

Answer 270

The cerebral cortex, basal nuclei, thalamus, and hypothalamus.

Question 271

The forebrain areas mediate higher brain functions such as? personality and learned behavior, motor planning, sensory processing, and emotional, endocrine, and autonomic functions, respectively.

Answer 271

.....such as personality and learned behavior, motor planning, sensory processing, and emotional, endocrine, and autonomic functions, respectively.

Question 272

The .......and ......... nerves are primarily forebrain nerves. All the nerves of the eye and extraocular muscles (II, III, IV, VI), along with the trigeminal nerve (V), course rostrally along the floor of the calvarium to exit through their retrobulbar foramina.

Answer 272

The olfactory (I) and optic (II) nerves are also primarily forebrain nerves. All the nerves of the eye and extraocular muscles (II, III, IV, VI), along with the trigeminal nerve (V), course rostrally along the floor of the calvarium to exit through their retrobulbar foramina.

Question 273

The pupillomotor fibers of the optic nerve project to the .............. to control the PLR, but the main projection of the optic nerve to the .............mediates vision. Lesions of the optic tract, lateral geniculate nuclei, or occipital lobes can produce a loss of vision with normal PLR (central blindness). If unilateral, the vision loss is limited to the ...............lateral visual field.

Answer 273

The pupillomotor fibers of the optic nerve project to the midbrain to control the PLR, the main projection of the optic nerve to the forebrain mediates vision. Lesions of the optic tract, lateral geniculate nuclei, or occipital lobes can produce a loss of vision with normal PLR (central blindness). If unilateral, the vision loss is limited to the contralateral visual field.

Question 274

In addition to..........., other sensory modalities such as conscious proprioception or .............are relayed through the thalamus to the appropriate area of the cerebral cortex.

Answer 274

In addition to vision, other sensory modalities such as conscious proprioception or hearing are relayed through the thalamus to the appropriate area of the cerebral cortex. Thus the ability of the animal to respond meaningfully to a sensory stimulus may be disrupted by lesions of the appropriate thalamic nuclei or region of the cerebral cortex. Like the PLR, some other simple responses such as the startle response to a loud noise or the dazzle response to a bright light are mediated at a subcortical level.

Question 275

Does the olfactory nerve bypass the thalamus?

Answer 275

The olfactory nerve projects directly to the olfactory bulbs and from there to the limbic areas of the forebrain, thus bypassing the thalamus.

Question 276

The hypothalamus controls .................function through the pituitary gland. It also regulates a variety of other homeostatic functions such as ...................., ..................... and ...................... Together with limbic areas, the hypothalamus is also involved in learning and memory, goal-directed behaviors, and emotions.

Answer 276

The hypothalamus controls endocrine function through the pituitary gland. It also regulates a variety of other homeostatic functions such as body temperature, osmolality, and autonomic functions. Together with limbic areas, the hypothalamus is also involved in learning and memory, goal-directed behaviors, and emotions.

Question 277

Epileptic seizures are caused by abnormal electrical activity in the ..............................; thus they should be considered an unambiguous sign of forebrain disease.

Answer 277

Epileptic seizures are caused by abnormal electrical activity in the cerebral cortex; thus they should be considered an unambiguous sign of forebrain disease.

Question 278

Which disease processes in the cerebral cortex can produce seizures?

Answer 278

Either focal damage to the cortex or diffuse metabolic effects can produce seizures (see Chapter 57).

Question 279

Hallmarks of forebrain disease?

Answer 279

Alterations of consciousness and behavior

Question 280

The traditional view of regulation of consciousness is that the RAS (reticular activating system ) in the brainstem projects to the cerebral cortex and “activates” it to produce normal consciousness (Figure 259-15). This concept is useful when considering causes of stupor and coma. Profound alterations of consciousness can result from?

Answer 280

Either a lesion in the brainstem affecting the RAS nuclei, the projections pathways of these systems toward the cortex, or diffuse disease affecting the cerebral cortex. (Lesions of the brainstem caudal to the RAS can render the animal quadriplegic without necessarily disrupting consciousness).

Question 281

Sensory neglect refers to?

Answer 281

Sensory neglect refers to a loss of meaningful response to stimuli in multiple sensory modalities without a lesion in the classic sensory pathways or a significant depression of consciousness. With unilateral lesions of the medial forebrain bundle or cerebral hemisphere, these signs can be limited to one side (hemineglect or hemiinattention). Hemineglect provides the most interesting illustration of the difference between sensory neglect and loss of consciousness or classic sensory or motor pathway lesions. A comatose animal has simply severely altered consciousness and not neglect.

Question 282

The decussation of sensory and motor pathways means?

Answer 282

Means that all sensory information originating from the right half of the animal's perceptual world goes to left forebrain and all control of motor activity directed toward the right side of that world originates from the left forebrain.

Question 283

The activation of the left cortex is necessary for the animal to direct its attention and behavior toward the right half of the world. Thus a unilateral lesion may be immediately apparent as?

Answer 283

A unilateral lesion may be immediately apparent as a tendency to circle. Such circles can be large, wandering circles where turning only occurs when the animal reaches a corner or other obstacle that requires a decision. Because all their attention is directed toward the side of the world associated with the functional cortex, they orient and turn in that direction (i.e., they circle toward the side of the lesion). Conversely, they neglect all sensory information arising from the side contralateral to the lesion. They do not track cotton balls or menace in the contralateral visual field. They have deficient conscious proprioception and postural reactions on that side.

Question 284

How will an animal with sensory neglect eat the food from the food bowl?

Answer 284

A hungry animal with sensory neglect will eat the food from half the food bowl (toward the food contralateral to the lesion). Olfactory inputs would tell them that food is around, but they will not eat from the neglected half because they cannot direct their attention toward that side of the world. (In humans, the difference between neglect and simple sensory deficits is readily illustrated by asking the patient to perform tasks such as drawing a picture (they would only draw the half corresponding to the functional half of the brain).

Question 285

The reticular activating system (RAS) nuclei project to the ......................cortex. A focal lesion of the RAS or diffuse cortical disease on one side will produce ..................

Answer 285

The reticular activating system (RAS) nuclei project to the ipsilateral cortex. A focal lesion of the RAS or diffuse cortical disease on one side will produce hemineglect.


Question 286

Why can an animal with bilateral forebrain damage that is not severe enough to produce stupor, still be able to walk relatively normally? (The walking, however, may not be directed toward any meaningful goal; instead the animal may pace aimlessly. As in the hemineglect cases, they may not respond to sensory stimuli. In the extreme case, they will not even be aware of the fact that they have walked into a corner and continue to push forward, head pressing against the corner)

Answer 286

The red nucleus in the midbrain is responsible for generating the gait in quadrupeds, and the corticospinal system is less important than in humans. Postural reactions require forebrain control and may be deficient, but an animal with bilateral forebrain damage that is not severe enough to produce stupor may still be able to walk relatively normally.

Question 287

Dogs and cats have a “bite reflex” whereby they will turn and snap at anything that touches them around the mouth. Why?

Answer 287

When forebrain lesions disrupt higher control, some subcortical behaviors can be released from their normal regulation. Normally, this reflex is regulated by higher centers, activated when needed such as in a fight, and inhibited when not needed as in nuzzling the owner. Like a spinal reflex, it can be exaggerated when released from inhibition, and the animal with forebrain disease may snap without warning or emotion when touched around the mouth.

Question 288

What is "magnet responses"?

Answer 288

In contrast to sensory neglect, where the animal ignores all stimuli, some brain-damaged animals develop “magnet responses” whereby they compulsively orient and move toward a stimulus. These orienting responses are subcortical responses released from normal forebrain control and become autonomous.

Question 289

Sleeping and feeding are goal-directed behaviors. Can these behaviors be disrupted by forebrain disease?

Answer 289

Many behaviors such as sleeping and feeding are goal-directed behaviors that can be disrupted by forebrain disease.

Question 290

A metabolic or toxic insult should not affect the brain asymmetrically, and diffuse, symmetrical signs would be expected. Because the ................. is the most metabolically demanding part of the brain, ..............signs tend to predominate.

Answer 290

Because the cerebral cortex is the most metabolically demanding part of the brain, forebrain signs tend to predominate.

Question 291

Can a localized disease process result in diffuse forebrain signs?

Answer 291

A localized disease process can result in diffuse forebrain signs through increased intracranial pressure.

Question 292

............ is the most metabolically demanding organ in the body. A large portion of the body's energy supply goes toward maintaining the resting membrane potential and neurotransmission. The nervous system has more limited energy metabolism pathways than other tissue and is thus more sensitive to disturbances of ....... or ........ supply. The brain is also very sensitive to exogenous or endogenous toxins.

Answer 292

The brain is the most metabolically demanding organ in the body. A large portion of the body's energy supply goes toward maintaining the resting membrane potential and neurotransmission. The nervous system has more limited energy metabolism pathways than other tissue and is thus more sensitive to disturbances of glucose or oxygen supply. The brain is also very sensitive to exogenous or endogenous toxins. The higher the level of function of a portion of the nervous system, the more sensitive it tends to be to metabolic insults. Thus forebrain signs are a common manifestation of systemic diseases.

Question 293

Most hereditary disease will have .............. traits or have a complex inheritance because dominant traits can be eliminated from a breed by simply not breeding affected dogs.

Answer 293

Most hereditary disease will have autosomal recessive traits or have a complex inheritance because dominant traits can be eliminated from a breed by simply not breeding affected dogs.

Question 294

Congenital malformations of the brain would typically be present from birth and nonprogressive. A few exceptions such as ........................can manifest later in life with progressive signs.

Answer 294

congenital hydrocephalus

Question 295

Once the neural tube has formed, differentiation of the various parts of the brain occurs and can be disrupted by similar genetic or environmental influences. Migration of neurons within the cerebral cortex leads to the characteristic ....... and ........and the normal laminar arrangement of neurons within the cortex.

Answer 295

Once the neural tube has formed, differentiation of the various parts of the brain occurs and can be disrupted by similar genetic or environmental influences. Migration of neurons within the cerebral cortex leads to the characteristic sulci and gyri and the normal laminar arrangement of neurons within the cortex. In lissencephaly, this normal migration is disrupted. Excessive production of small gyri (polymicrogyria) has also been reported as a familial disease of Standard Poodles, sometimes associated with hydrocephalus. The occipital lobes are preferentially affected with cortical blindness being the primary clinical sign

Question 296

Cerebellar hypoplasia is seen most commonly in cats affected by?

Answer 296

In utero or early neonatal infection with the feline panleukopenia virus. The rapidly multiplying granule cells of the cerebellum are sensitive to damage by the virus at this stage of development. Canine parvovirus infection can also produce similar damage to the developing cerebellum. Cerebellar hypoplasia can also occur as isolated malformation without evidence of infection, or as part of a more generalized brain development abnormality.

Question 297

What is Chiari-Like Malformations?

Answer 297

The Chiari type 1 malformation consists of an elongation of the caudal, ventral cerebellum through the foramen magnum. In addition to compressing the medulla, the herniated cerebellum obstructs normal outflow of CSF from the calvarium, which can lead to secondary hydrocephalus. As the brain expands with each heart beat, the herniated cerebellum is forced caudally, generating pulsatile compression of the cervical spine. This leads to syringomyelia of the cervical spinal cord. In addition to those referable to hydrocephalus and cerebellar compression, clinical signs include cervical myelopathy signs: ataxia, proprioception deficits, weakness, and cervical pain. Excessive scratching of the ear, neck, or shoulder may be the major presenting complaint. Seen in CKCS

Question 298

Hydrocephalus can be either............. or ................ It can also be categorized as either o........................... or .......................

Answer 298

Hydrocephalus can be either congenital or acquired. It can also be categorized as either obstructive or communicating. Obstructive hydrocephalus is acquired when a disease process such as neoplasia, hemorrhage, or inflammation occludes the pathway.

Question 299

When does obstructive hydrocephalus occur?

Answer 299

Obstructive hydrocephalus occurs when there is a blockage of the flow of CSF through the ventricular system.

Question 300

Where does obstructive hydrocephalus commonly occur?

Answer 300

The obstruction typically occurs at the bottlenecks of CSF flow, the connection between the lateral ventricle and the third ventricle (the intraventricular foramen) or most commonly, the connection between the third and fourth ventricle (the mesencephalic aqueduct).

Question 301

In communicating hydrocephalus, no obstruction to flow is seen and ..................ventricular system dilates.

Answer 301

In communicating hydrocephalus, no obstruction to flow is seen and all the ventricular system dilates.

Question 302

External hydrocephalus results from........?

Answer 302

External hydrocephalus results from CSF accumulating in the subarachnoid space, presumably due to obstruction of flow secondary to inflammation. This will produce clinical signs if causing too much compression, particularly on the cerebrum.

Question 303

Clinical signs of hydrocephalus include?

Answer 303

Behavioral changes, ataxia, and seizures. A ventrolateral strabismus is common in congenital hydrocephalus. Lateralized signs such as circling will be evident with obstruction of the intraventricular foramen causing dilation of one lateral ventricle.

Question 304

The spongiform encephalopathies compromise a heterogeneous group of diseases that have in common spongiform change within the brain at necropsy (Some lysosomal storage diseases may also be characterized by vacuolation of neurons). They can be subdivided depending on....?

Answer 304

Whether the vacuolation occurs within the myelin sheaths in the white matter (e.g leukoencephalopathies) or in the gray matter within neurons or their process The gray matter spongiform encephalopathies include both hereditary and acquired (transmissible) diseases. Spongiform change in the gray matter also occurs in other diseases including rabies and hereditary disease.

Question 305

Neuroaxonal dystrophies are characterized by?

Answer 305

Swellings within the axons called spheroids.

Question 306

Leukoencephalopathies are diseases of myelin and thus affect predominantly the ........ matter.

Answer 306

The white matter. The spongiform encephalopathies, which affect the white matter, are often referred to as spongy degenerations of the white matter or spongy leukodystrophies to clearly differentiate them from the TSEs, which affect primarily gray matter.

Question 307

Leukoencepalopathies typically produce cerebellar or long tract signs, although many variations exist. In spongy degeneration of white matter, the vacuolation is caused by ....?

Answer 307

By splitting of the myelin sheaths. (Other leukoencephalopathies disrupt myelin or axons without producing vacuolation and would be referred to as leukodystrophies).

Question 308

Hypomyelinogenesis refers to?

Answer 308

The conditions where myelin never forms normally, whereas in dysmyelinogenesis myelin formation is present but delayed or abnormal. Congenital disorders of myelin formation most commonly present as generalized tremors and dysmetria noticeable from the first attempts at walking.

Question 309

Lysosomal Storage Disease: characterized by?

Answer 309

An accumulation of metabolic byproducts within lysosomes. The substrates for catabolism within lysosomes include sphingolipids (a major component of myelin), oligosaccharides, mucopolysaccharides, glycoproteins, and proteins. The storage diseases are typically caused by a deficiency in a key enzyme in the breakdown of one of these molecules, and without the enzyme, the substrate accumulates within the lysosome. The syndromes are usually named for the accumulated product.

Question 310

What are lysosomes? Why are they of value for the rest f the cell?

Answer 310

The cellular organelles where breakdown of complex macromolecules occurs. This compartmentalization allows for a more acidic pH within the lysosome and protects the rest of the cell from digestion. Accumulation of the storage product takes time; thus most storage diseases have a delayed onset of signs even though the enzyme has been deficient from birth.

Question 311

Common first signs of lysosomal storage diseases?

Answer 311

Cerebellar signs of dysmetria, truncal ataxia, and nystagmus are often the first signs of storage diseases. In some lysosomal storage diseases, signs of other organ involvement may be apparent. (Ocular abnormalities can include visible changes in the retina or cataract formation. Skeletal or facial malformations are especially prominent in the mucopolysaccharidoses and may be apparent on radiographs. Cardiac, hepatic, splenic, or lymph node enlargement may accompany the neurologic signs).

Question 312

Why is the cerebellum very sensitive to disorders affecting myelin or information processing?

Answer 312

The cerebellum is very dependent on fast conduction to get sensory feedback during execution of a movement, and complex integration of sensory and motor information is necessary. Thus the cerebellum is very sensitive to disorders affecting myelin or information processing.

Question 313

How does ceroid lipofuscinosis differs from the other lysosomal storage diseases?

Answer 313

In that the storage products are proteins. (Diminished vision is usually the first sign of CL)

Question 314

The cerebellar ataxias can be divided into neonatal, early, and delayed onset. In most of these delayed-onset ataxias of dogs and cats, the ...............of the cerebellum degenerate. Because the ............... is the sole..................from the cerebellar cortex, degeneration results in a loss of cerebellar function.

Answer 314

The cerebellar ataxias can be divided into neonatal, early, and delayed onset. In most of these delayed-onset ataxias of dogs and cats, the Purkinje cells of the cerebellum degenerate. Because the Purkinje cell is the sole efferent from the cerebellar cortex, degeneration results in a loss of cerebellar function. Although Purkinje cell degeneration is the most common type of degeneration described, other parts of the cerebellum can be affected.

Question 315

What is dyskinesia?

Answer 315

It is a general term for a disorder of movement usually characterized by involuntary, stereotyped movements caused by disease affecting the basal ganglia (extrapyramidal) motor systems or their neurotransmitters. Dyskinesias can involve the entire body or be limited to one side or to the face.

Question 316

What is dystonia?

Answer 316

Refers to a sustained abnormal contraction often producing abnormal posturing or torticollis. Such movement disorders have not been well documented in animals.

Question 317

There are reports of paroxysmal abnormal movements in dogs that do not appear to be seizures. Generalized seizures are distinguished by a loss of ............. but in focal motor seizures, .................... may not be impaired.

Answer 317

There are reports of paroxysmal abnormal movements in dogs that do not appear to be seizures. Generalized seizures are distinguished by a loss of consciousness but in focal motor seizures, consciousness may not be impaired.

Question 318

What is Scotty cramp?

Answer 318

Scotty cramp is a condition of Scottish Terriers characterized by episodes of rigidity with excitement or exercise. Affected dogs develop limb rigidity, which can result in recumbency in severely affected dogs. The cause of the muscle hypertonicity is not clear, but a central motor problem is suspected.

Question 319

Fine, fast tremors (enhanced physiologic tremors) are common with a wide variety of conditions; such as?

Answer 319

weakness, fatigue, fear, pain, hypoglycemia, pheochromocytoma, hyperthyroidism, and certain drugs or toxins such as pyrethrins or caffeine.

Question 320

Little white shakers syndrome? Breed?

Answer 320

An idiopathic tremor syndrome was first reported in Maltese dogs and West Highland White Terriers and called “little white shakers” syndrome.

Question 321

Encephalitis refers to?

Answer 321

An inflammation of the brain. Most infectious or inflammatory diseases of the nervous system involve the spinal cord, as well as the brain producing multifocal disease.

Question 322

Potential etiologies of encephalitis?

Answer 322

Viral, bacterial, rickettsial, protozoal, fungal, and parasitic. A few diseases affect the brain almost exclusively.

Question 323

Encephalitis is typically an acute disease but in some cases , it can be chronic and insidious. Which scenarios for ex?

Answer 323

Canine distemper or feline immunodeficiency virus (FIV)

Question 324

Encephalitis: typical presentation?

Answer 324

Some infections can be quite focal and signs will reflect the area of the brain affected, whereas others will produce more diffuse signs. Altered mentation with focal facial muscle twitching and/or seizures can be seen.

Question 325

Viral Encephalitis: Rabies: How can the virus cause neurologic disease?

Answer 325

If the virus gains entry through a wound on the limbs, rabies may affect the spinal cord, producing an ascending LMN paralysis prior to brain signs. Commonly, however, the bite occurs on the face and the signs will reflect cranial nerve and forebrain involvement.

Question 326

Clinical signs due to rabies virus?

Answer 326

For the first few days following infection, there may be a fever, pruritus of the bite site, and anxious or irritable behavior. Progression and signs of the disease are quite variable with considerable overlap between the two general forms of the disease. In the paralytic or dumb form of rabies, LMN paralysis of cranial nerves can produce a dropped jaw, dysphagia, laryngeal paralysis, and voice change. Signs progress over days to coma and respiratory arrest. The furious form consists of the classic behavior changes of rabies.

Question 327

There is increasing evidence that FIV infection can cause an encephalopathy not related to secondary infection. Which signs?

Answer 327

Affected cats develop progressive, symmetric forebrain signs including depression, restlessness, learning and memory deficits, and mild coordination difficulties.

Question 328

Encephalitis of Unknown Cause: What is Pug encephalitis?

Answer 328

A necrotizing meningoencephalitis that affects young adult Pug dogs. Affected dogs typically develop an acute onset of seizures and other forebrain signs. Maltese and Yorkshire Terriers develop a similar encephalitis, although brainstem involvement is more common in the Yorkshires. CSF analysis shows a lymphocytic pleocytosis. Histologically there is asymmetric necrosis and inflammation affecting both gray and white matter. Many affected dogs die within days of the onset of signs, though some may survive for months.

Question 329

Granulomatous meningoencephalomyelitis (GME) affect?

Answer 329

Can affect the spinal cord but primarily causes encephalitis. Affected dogs tend to be young adults but any age may be affected. Onset of signs is typically acute.

Question 330

In dogs, atherosclerosis is seen in .............. and idiopathic ..................., and stroke can occur in these patients.

Answer 330

In dogs, atherosclerosis is seen in hypothyroidism and idiopathic hyperlipidemia, and stroke can occur in these patients.

Question 331

Although a rich ................. usually prevents signs with venous thrombosis, a severe occlusion may result in impaired blood flow to the tissues drained.

Answer 331

Although a rich collateral drainage usually prevents signs with venous thrombosis, a severe occlusion may result in impaired blood flow to the tissues drained.

Question 332

Tumors that arise from brain tissue are broadly classified as primary or secondary. Primary intracranial neoplasms include all tumors that are derived from ......., ............, or .............tissues, whereas secondary intracranial neoplasms are extraneural in origin and directly invade neural tissue or systemically spread from a distant site.

Answer 332

Tumors that arise from brain tissue are broadly classified as primary or secondary. Primary intracranial neoplasms include all tumors that are derived from neural, glial, or meningeal tissues, whereas secondary intracranial neoplasms are extraneural in origin and directly invade neural tissue or systemically spread from a distant site.

Question 333

............ is the most common brain tumor in dogs and cats. Glial cell tumors are the second most common primary brain tumor in dogs and fourth most common in cats.[118]

Answer 333

Meningioma is the most common brain tumor in dogs and cats. Glial cell tumors are the second most common primary brain tumor in dogs and fourth most common in cats

Question 334

Meningioma?

Answer 334

They are mesenchymal tumors that arise from the meninges. Although most canine meningiomas are benign, dogs have a higher incidence of atypical tumors

Question 335

Neuroepithelial tumors are derived from?

Answer 335

Neural tissues composed of the glia, choroid plexus, ependyma, and neurons.

Question 336

Central nervous system lymphoma: ...............CNS lymphoma is uncommon in dogs and cats, whereas ............. CNS lymphoma is an element of a multicentric process.

Answer 336

Central nervous system lymphoma: Primary CNS lymphoma is uncommon in dogs and cats, whereas secondary CNS lymphoma is an element of a multicentric process.

Question 337

The majority of lymphoma cells in cats and dogs are strongly positive for ........, a T lymphocyte marker.

Answer 337

The majority of lymphoma cells in cats and dogs are strongly positive for CD3, a T lymphocyte marker.

Question 338

Secondary intracranial neoplasm can occur by secondary metastasis inside the cranial vault from a distant primary site or by direct extension from adjacent tissue. ..........tumors are the most common tumor type that spreads by direct extension.

Answer 338

Nasal tumors are the most common tumor type that spreads by direct extension. Other tumor types that invade by direct extension include squamous cell carcinoma, pituitary tumors, and osteochondrosarcomas.

Question 339

Paraneoplastic syndromes affect all levels of nervous system. Paraneoplastic syndromes result when an appropriate immune response against a tumor .........cross-reacts with similar ...........expressed by the nervous system.

Answer 339

Paraneoplastic syndromes result when an appropriate immune response against a tumor antigen cross-reacts with similar antigens expressed by the nervous system.

Question 340

Cushing's disease or pituitary-dependent hyperadrenocorticism (PDH) comprises ........ to .... of dogs with naturally occurring Cushing's syndrome and is associated with excessive adrenocorticotropin hormone (ACTH) secretion

Answer 340

Cushing's disease or pituitary-dependent hyperadrenocorticism (PDH) comprises 80% to 85% of dogs with naturally occurring Cushing's syndrome and is associated with excessive adrenocorticotropin hormone (ACTH) secretion. These tumors are generally less than 1 cm in diameter and cause little damage to surrounding neural tissue. However, these tumors may continue to grow throughout the animal's life, ultimately resulting in both neurologic deterioration and death. CNS dysfunction in dogs may be related less to tumor size and perhaps more to rapidity of tumor growth. The most common neurologic signs in cats are blindness and altered mentation.

Question 341

The function of the vestibular system?

Answer 341

The maintenance of posture, balance, and tone of the head and body in relation to gravitational forces and movement.

Question 342

The vestibular system is divided into:

Answer 342

It is divided into peripheral and central components

Question 343

The peripheral vestibular system consists of?

Answer 343

The membranous labyrinth and the vestibular portion of the vestibulocochlear nerve (cranial nerve [CN] VIII).

Question 344

How does the structures in the peripheral vestibular system co-work?

Answer 344

The membranous labyrinth is a series of fluid-filled structures consisting of three semicircular canals, the utricle, and the saccule, which are responsible for the vestibular function. It also includes the cochlea, which is involved in hearing. The utricle and saccule contain a sensory area called the macula, which is covered with hair cells. Its function is to localize the static position of the head with respect to gravity and also to detect linear acceleration. The semicircular canals are filled with fluid called endolymph. There is a sensory area at one end of each canal called the crista ampullaris, which is also covered with hair cells. The function of the semicircular canals is to detect the movement of the head in every position and rotational angle. Because each canal is oriented in a different plane, rotation of the head in any direction will stimulate at least one canal. The impulses generated by the maculae and cristae travel through the vestibular portion of the CN VIII to any of the central components of the vestibular system.

Question 345

The central vestibular components include?

Answer 345

The four pairs of vestibular nuclei on each side in the brainstem and the cerebellum (fastigial nucleus and flocculonodular lobe).

Question 346

How does the structures in the central vestibular system co-work?

Answer 346

Many axons from the CN VIII synapse in the vestibular nuclei, whereas others will ascend directly to the cerebellum via the caudal cerebellar peduncle. From the vestibular nuclei, some axons will project to the spinal cord (vestibulospinal tract) to influence the extensor tone by causing facilitation on the ipsilateral extensor muscles and inhibition on the ipsilateral flexor muscles. The cerebellum provides an inhibitory effect on the vestibular nuclei, preventing excessive extensor tone. Other axons will project in the medial longitudinal fasciculus to synapse in the nuclei of the CN III, IV, and VI, thereby adjusting the position of the eyes in relation to the position and movement of the head. Integrity of this pathway is responsible for the physiologic nystagmus (also called oculocephalic reflex or “doll's eye”) that is generated when the head is moving from side to side or up and down. A few axons will also project to the vomiting center in the reticular formation of the medulla (playing a role in motion sickness), whereas others will ascend to the cerebral cortex for conscious awareness of the head and body's position.

Question 347

Can lesions i both peripheral and/or central components of the vestibular system cause vesitbular dysfunction?

Answer 347

A lesion of any peripheral or central component of the vestibular system can cause vestibular dysfunction. With pure vestibular disturbance, strength will be preserved. Most disease processes will cause unilateral lesion leading to loss of balance and head tilt to one side, but bilateral involvement is possible as well.

Question 348

What is the most common and most consistent sign of a unilateral or asymmetrical vestibular disorder?

Answer 348

A head tilt is the most common and most consistent sign of a unilateral or asymmetrical vestibular disorder.

Question 349

How is the head tilt in patients affected with vesitubular disease? To which side is the head tilted?

Answer 349

When all of the components of the vestibular system are working, there is equal extensor tone on each side and balance and equilibrium are maintained and adjusted. With a lesion on one side, there will be a lack of facilitation of the extensor muscles on that side, leading to imbalance with the normal side “pushing” the body and head toward the abnormal side. This causes a head tilt on the side of the lesion.

Question 350

It is important to differentiate a head tilt from a head turn (indicative of forebrain lesion): how can this be done?

Answer 350

In head tilt; one ear is held lower than the other and the eyes will not be parallel to the floor. With a head turn (usually indicative of a forebrain lesion), both ears and eyes should be parallel to the ground. Patients with bilateral vestibular involvement may not have a head tilt at all unless one side is more affected than the other. These animals will tend to have wide head excursion from side to side.

Question 351

In which scenarios might the head be tilted to the opposite side of the lesion?

Answer 351

In cases of cerebellar involvement, the head might be tilted to the opposite side of the lesion (see Paradoxical Syndrome).

Question 352

Vestibular ataxia is characterized by a wide-based stance and loss of balance on the side of the lesion. The head and body can sway and the animal will often lean, fall, or even roll to one side. Patients will often fall when shaking their heads. The animal may walk in circles (vestibular circling) because of constantly falling on one side despite attempting to go in a straight line. This must be differentiated from compulsive circling (from forebrain lesion). How?

Answer 352

In compulsive circling; there would be no head tilt and the patient should be able to walk in a straight line when motivated.

Question 353

Vestibular ataxia: The presence of paresis and/or GP deficits indicates a ..................... lesion affecting the descending motor pathways and the ascending proprioceptive tracts. However, the evaluation of GP can be difficult initially if the patient is severely affected. Also, older dogs with chronic back problems may have GP deficits unrelated to the vestibular signs.

Answer 353

The presence of paresis and/or GP deficits indicates a central lesion affecting the descending motor pathways and the ascending proprioceptive tracts. However, the evaluation of GP can be difficult initially if the patient is severely affected. Also, older dogs with chronic back problems may have GP deficits unrelated to the vestibular signs.

Question 354

Vestibular ataxia: In cases of bilateral disturbance, the animal will typically stand crouched and low to the ground. In cases of unilateral involvement, the animal will prefer to lie .................... of the lesion.

Answer 354

In cases of bilateral disturbance, the animal will typically stand crouched and low to the ground. In cases of unilateral involvement, the animal will prefer to lie on the side of the lesion.

Question 355

Nystagmus is a rhythmic, involuntary movement of the eyes. It can have equal movement on both sides (......................nystagmus) or most commonly has a fast phase and a slow phase (............... nystagmus). By convention, the direction of the nystagmus is described in regards to its ..............phase and can further be characterized as horizontal, vertical, or rotary.

Answer 355

Nystagmus is a rhythmic, involuntary movement of the eyes. It can have equal movement on both sides (pendular nystagmus) or most commonly has a fast phase and a slow phase (jerk nystagmus). By convention, the direction of the nystagmus is described in regards to its ............. phase and can further be characterized as horizontal, vertical, or rotary.

Question 356

Is pendular nystagmus a sign of vestibular dysfunction?

Answer 356

Pendular nystagmus is not a sign of vestibular dysfunction and is mainly recognized in Siamese, Himalayan, Birman, and crosses of these breeds. It is believed to originate from a congenital defect in the visual pathways. It has also been reported in diseases of the cerebellum.

Question 357

What is physiologic nystagmus?

Answer 357

The conjugated eye movement occurring during head movement in order to stabilize images on the retina. For example, movement of the head to the right will cause a slow movement of the eyes to the left (slow phase) because of vestibular activation, followed by a quick release from a brainstem reflex resulting in the eyes moving quickly to the right (fast phase).

Question 358

How is the physiologic nystagmus affected in vestibular disease?

Answer 358

In vestibular diseases, the physiologic nystagmus may be reduced in both eyes when the head is turned toward the side of the lesion. In cases of bilateral involvement, the physiologic (and pathologic) nystagmus may be completely absent because of lack of vestibular activation on both sides.

Question 359

Is pathologic nystagmus always present in vestibular disease?

Answer 359

Pathologic nystagmus is frequently, but not always, present in vestibular disease. It can be spontaneous, which occurs when the head is in the normal position, or positional, which is present only when the head is placed in an unusual position (e.g., in complete extension or with the animal in dorsal recumbency).

Question 360

How is the pathologic nystagmus in peripheral vesitbular disease compared to in central vesitbular disease?

Answer 360

In peripheral vestibular disease, the pathologic nystagmus can be horizontal or rotary and the fast phase is always away from the lesion. In central disease the pathologic nystagmus can be in any plane (including vertical), can change direction with different positions of the head, and the fast phase can be toward the lesion. Therefore, identification of a vertical nystagmus or a nystagmus with the fast phase toward the lesion is an indication of central involvement. (One prospective study also suggested that a resting nystagmus of more than 66 beats per minute was suggestive of a peripheral disease)

Question 361

Vestibular strabismus is characterized by? Can the eye move normally? Can it be seen with a peripheral or central vestibular lesion?

Answer 361

A ventral deviation of the ocular globe on the side of the lesion when the head is in extension (positional strabismus). However, the eye can move normally because there is no paralysis of any of the extraocular muscles. This type of strabismus can be seen with a peripheral or central vestibular lesion.

Question 362

Cranial Nerve Deficits: Although not exactly part of the vestibular syndrome, a CN deficit can be seen along with vestibular signs. How? deficitWhich nerves involved? Why Horner's syndrome from a peripheral disease (also in central?)

Answer 362

In the brainstem, the facial nerve (CN VII) is close to the vestibulocochlear nerve and it travels close to the inner ear as well. For this reason, a facial nerve paresis or paralysis (inability to close the eyelids, droopy face and ear) may be noticed with both peripheral and central diseases. The sympathetic innervation of the eye also travels close to the inner ear and Horner's syndrome (miosis, entophthalmia, ptosis, prolapse of the third eyelid) can occur from a peripheral disease but is seen rarely in central diseases. Peripheral disease: CN VII deficit only. Any other CN involvement indicates a central origin of the disease.

Question 363

Why nausea and vomiting in patients affected by vesitbular syndrome? Both in peripheral and central disease?

Answer 363

Nausea (drooling, lack of appetite) and vomiting are frequently seen and can be related to motion sickness or the result of a problem in the pathways between the vestibular nuclei and the vomiting center in the brainstem. Nausea and vomiting can be seen in both peripheral and central diseases, although vomiting might be more common with peripheral diseases.

Question 364

Patients with vestibular disease can obviously be very anxious and quite disoriented by the lack of balance. However, an attempt should be made to try to differentiate this from central depression or obtundation indicating .......... involvement or even from confusion and compulsive behavior suggestive of .............

Answer 364

Patients with vestibular disease can obviously be very anxious and quite disoriented by the lack of balance. However, an attempt should be made to try to differentiate this from central depression or obtundation indicating brainstem involvement or even from confusion and compulsive behavior suggestive of forebrain disease. Some degree of mental depression usually occurs with central diseases because the vestibular nuclei are in close proximity to the diffuse ascending reticular activating system responsible for normal alertness.

Question 365

What is paradoxical Syndrome? How can the side of the lesion be identified?

Answer 365

The cerebellum is inhibitory to the ipsilateral vestibular nuclei. If there is a lack of inhibition, the vestibular nuclei will appear “hyper” on that side, causing excess in extensor tone that will “push” the head and the body on the other side. This causes the head to be tilted away from the lesion. The side of the lesion can be identified by the presence of concomitant deficits (ipsilateral GP deficit, paresis, hypermetria, or CN deficits). A paradoxical vestibular syndrome can be seen with lesions in the flocculonodular lobe of the cerebellum, the caudal cerebellar peduncle, and the rostral and medial vestibular nuclei in the medulla.

Question 366

Clinical Signs Associated with Peripheral and Central Diseases: se tabell 260-1

Answer 366

Clinical Signs Associated with Peripheral and Central Diseases: se tabell 260-1

Question 367

The best way to diagnose a central involvement in patients affected by vestibular syndrome?

Answer 367

Identify deficits that cannot be attributed to the peripheral components alone such as GP deficits, change in mentation (other than anxiety), or CN deficits (other than CN VII). Presence of a consistent vertical nystagmus with no rotary component or of nystagmus with the fast phase toward the lesion is also suggestive of a central involvement. The presence of Horner's syndrome suggests a lesion in the middle/inner ear.

Question 368

The most common cause of peripheral vesitubular disease in dogs and cats? Other etiologies?

Answer 368

Otitis interna/media (OIM). The etiology is most commonly extension of otitis externa in dogs, but an ascending infection from the nasopharynx (via the Eustachian tube) seems more common in cats. Hematogenous spread is also possible. The most common bacteria are Staphylococcus species, Streptococcus, Pseudomonas, Proteus, and Malassezia pachydermatis. the damage on the facial nerve may be irreversible.

Question 369

Peripheral vesitbular disease: Dogs and cats with OIM often have ......... nerve involvement as well and sometimes ......... syndrome. Other common clinical signs?

Answer 369

Dogs and cats with OIM often have facial nerve involvement as well and sometimes Horner's syndrome. Pain in the ear and/or on opening of the mouth or reluctance to chew hard food is also common and can help in reaching a diagnosis.

Question 370

Always fascial paralysis and miosis in patients affected by peripheral vesitbular disease?

Answer 370

Early in the disease process, irritation of the facial and sympathetic nerves may cause facial spasms (instead of paralysis) and mydriasis (instead of miosis), respectively, before progressing to the more typical signs.

Question 371

Peripheral vestibular disease: Nasopharyngeal polyps are pedunculated growths resulting from chronic inflammation. In cats, they may be congenital. They originate from the ........., the ........... or the lining of the tympanic bulla. Young cats between 1 and 5 years old are most commonly affected, but this can occur in dogs as well. In addition to causing signs of middle/inner ear disease, they can cause upper .............signs or ............signs (gagging, dysphagia).

Answer 371

Nasopharyngeal polyps are pedunculated growths resulting from chronic inflammation. In cats, they may be congenital. They originate from the auditory tube, the nasopharynx, or the lining of the tympanic bulla. Young cats between 1 and 5 years old are most commonly affected, but this can occur in dogs as well. In addition to causing signs of middle/inner ear disease, they can cause upper respiratory signs or pharyngeal signs (gagging, dysphagia).

Question 372

Idiopathic peripheral vestibular Disease is seen in cats of all ages and in older dogs, which is why it is sometimes called “old dog vestibular disease” or “canine geriatric vestibular disease.” The condition is characterized by?

Answer 372

Characterized by an acute or peracute onset of peripheral vestibular signs. Unilateral signs are more common. It can easily be misinterpreted as a stroke or a seizure. The vestibular signs can be mild but are usually quite severe to the extent that the patient is severely incapacitated, making a complete neurologic examination difficult initially. Nausea and vomiting are common and although the animal may be quite anxious, there is no sign of central involvement or middle ear disease (i.e., no facial paralysis or Horner's syndrome).

Question 373

Etiology of idiopathic peripheral vestibular disease?

Answer 373

The etiology is unknown but could be an abnormality in the endolymph. In cats, the condition is more common in the northeastern part of the United States and Canada in the summer and early fall and may be caused by the migration of small Cuterebra larvae through the ear canal. A similar presentation is seen in the southeastern part of the United States in cats ingesting the tail of the blue tail lizard.

Question 374

Peripheral vestibular disease can occur secondary to which endocrinologic disease?

Answer 374

Vestibular disease secondary to hypothyroidism is mainly recognized in middle-aged to older dogs. The vestibular signs are usually mild to moderate and can be unilateral or bilateral and may result from segmental demyelination.The condition can be acute or chronic and affected dogs may not display the more typical signs of hypothyroidism, although hypercholesterolemia is common. There may be concomitant facial nerve involvement and the patient may be very lethargic, which can make differentiation from central disease difficult. (A concomitant central involvement is possible because the CSF analysis sometimes shows an increase in protein concentration)

Question 375

Peripheral vestibular disease can occur due to ototoxicity and Iatrogenic Trauma in humans. Samt problem in animals?

Answer 375

In reality, vestibular disease secondary to ototoxicity is probably not a common occurrence. Iatrogenic trauma during ear cleaning is probably more common than true ototoxicity.

Question 376

Other less common etiologies of peripheral vestibular disease?

Answer 376

-Congenital unilateral vestibular disease has been reported in a few dog breeds and cat breeds. Bilateral congenital disease has been reported in Akitas and Beagles. The etiology can be either a malformation or degeneration of the inner ear structures. There is no treatment but the signs usually improve because of compensation. -Tumors of the ear canal or middle ear are not common and tend to be aggressive, especially in cats. Because of the proximity of the trigeminal nerve (CN V) to the CN VIII, dogs with a trigeminal nerve–sheath tumor can present with vestibular signs. On neurologic examination, signs of trigeminal involvement should be obvious (ipsilateral atrophy of the masticatory muscles, reduced palpebral reflex, and facial sensation).

Question 377

Which disease processes that can affect the brain has the potential to cause a vestibular syndrome?

Answer 377

Any disease process that can affect the brain has the potential to cause a vestibular syndrome. However, some conditions and diseases tend to affect the vestibular components preferentially.

Question 378

Inflammatory Diseases: cause of vestibular disturbance?

Answer 378

Inflammatory diseases of the brain (encephalitis), either infectious or noninfectious, can affect any part of the CNS and often produce multifocal signs. They are a common cause of vestibular disturbance. Some diseases tend to cause vestibular signs more often and are discussed briefly here.

Question 379

............virus commonly causes cerebellar and vestibular signs that can progress to tetraparesis. In older dogs, systemic signs and myoclonus are often lacking, making the diagnostic difficult.

Answer 379

Canine distemper virus commonly causes cerebellar and vestibular signs that can progress to tetraparesis. In older dogs, systemic signs and myoclonus are often lacking, making the diagnostic difficult.

Question 380

In cats, vestibular signs can be seen with ................. The .............virus induces a pyogranulomatous and immune complex–mediated vasculitis.

Answer 380

In cats, vestibular signs can be seen with feline infectious peritonitis (FIP). The FIP virus induces a pyogranulomatous and immune complex–mediated vasculitis.

Question 381

Other infectious agens potentially causing vestibular disease?

Answer 381

Rocky Mountain spotted fever (RMSF) and ehrlichiosis are reported to cause neurologic signs Fungal diseases, in particular cryptococcosis Bacterial diseases are rare and mainly result from extension of middle ear diseases. Toxoplasma gondii infection in dogs and cats Neospora caninum in dogs Rabies

Question 382

Noninfectious inflammatory diseases of the brain are also called meningoencephalitis of unknown etiology (MUE) or steroid-responsive encephalitis. Ex of such diseases?

Answer 382

Granulomatous meningoencephalitis (GME) and other breed-specific encephalitis (e.g., necrotizing leukoencephalitis of Yorkshire, necrotizing encephalitis of Pugs), which carry a guarded to poor prognosis.

Question 383

Primary or secondary tumors can affect the brainstem and cerebellum. They are a common cause of central vestibular disorders. The most common primary tumors affecting the vestibular components of the CNS in dogs and cats are?

Answer 383

Meningioma

Question 384

A cerebrovascular accident (CVA) or stroke is characterized by a sudden onset of nonprogressive focal signs of brain dysfunction. It occurs when the blood flow to a region of the brain is obstructed by an infarct (thrombus or embolism), a hemorrhage, or an arterial spasm and may result in death of brain tissue. The most common location for CVA in dogs is?

Answer 384

The cerebellum

Question 385

............... toxicity in dogs causes bilateral central vestibular signs usually accompanied by cerebellar signs (intention tremors, hypermetria). Resting or positional vertical nystagmus is a common finding. The signs are acute and can be accompanied or preceded by anorexia and vomiting. The exact mechanism of toxicity is unknown but metronidazole seems to interact with the ........ receptors in the cerebellum and vestibular nuclei.

Answer 385

Metronidazole toxicity in dogs causes bilateral central vestibular signs usually accompanied by cerebellar signs (intention tremors, hypermetria). Resting or positional vertical nystagmus is a common finding. The signs are acute and can be accompanied or preceded by anorexia and vomiting. The exact mechanism of toxicity is unknown but metronidazole seems to interact with the GABA receptors in the cerebellum and vestibular nuclei. When using metronidazole, a dosage of 30 mg/kg/day is generally considered adequate and relatively safe.

Question 386

In cats, metronidazole toxicity usually causes ...............disturbance (seizures, blindness, ataxia) instead of vestibular signs.

Answer 386

In cats, metronidazole toxicity usually causes forebrain disturbance (seizures, blindness, ataxia) instead of vestibular signs.

Question 387

.............deficiency causes bilateral necrosis and hemorrhage in the brainstem. In cats, the vestibular and ocular nuclei are often affected, leading to vestibular signs and dilated, unresponsive pupils. These cats often have a marked ventroflexion of the neck as well. Animals that are anorexic or fed for 2 to 4 weeks with a diet rich in ............ (raw fish) or with food subjected to excessive heat (>100° C or 212° F) are at risk of deficiency.

Answer 387

Thiamine (vitamin B1) deficiency causes bilateral necrosis and hemorrhage in the brainstem. In cats, the vestibular and ocular nuclei are often affected, leading to vestibular signs and dilated, unresponsive pupils. These cats often have a marked ventroflexion of the neck as well. Animals that are anorexic or fed for 2 to 4 weeks with a diet rich in thiaminase (raw fish) or with food subjected to excessive heat (>100° C or 212° F) are at risk of deficiency.

Question 388

Some malformations and congenital anomalies can cause vestibular signs. Among those, the ...............malformation syndrome common in Cavalier King Charles Spaniels and sometimes seen in other small-breed dogs is probably the most common. .............. cyst, especially in the quadrigeminal cistern, can also cause cerebellar deficits.

Answer 388

Some malformations and congenital anomalies can cause vestibular signs. Among those, the caudal occipital malformation syndrome common in Cavalier King Charles Spaniels and sometimes seen in other small-breed dogs is probably the most common. Arachnoid cyst, especially in the quadrigeminal cistern, can also cause cerebellar deficits.

Question 389

Head trauma can cause vestibular signs because of ...............and/or ........... involvement. If the brainstem is affected, obtundation and even stupor or coma are likely. The prognosis for head trauma is fair for a ................lesion and very guarded with .....................involvement.

Answer 389

Head trauma can cause vestibular signs because of cerebellar and/or brainstem involvement. If the brainstem is affected, obtundation and even stupor or coma are likely. The prognosis for head trauma is fair for a cerebellar lesion and very guarded with brainstem involvement.

Question 390

Degenerative Diseases: give ex of some diseases that can cause vestibular signs.

Answer 390

Storage disease, abiotrophy, and cerebellar hypoplasia among others can cause vestibular signs. These diseases are usually progressive and the prognosis is guarded to poor.

Question 391

Highest on the differential diagnosis list for dogs and cats with multifocal/diffuse encephalopathy? (4)

Answer 391

Inflammatory disorders, metabolic disorders, toxins, and multifocal/metastatic neoplasia are

Question 392

The clinician should be aware that focal brain lesions can lead to multifocal signs of encephalopathy due to several mechanisms: Which 3?

Answer 392

(1) an extensive mass that invades more than one region of the brain; (2) edema surrounding a focal mass, producing a “second mass” effect; and (3) obstruction by a brain lesion of normal cerebrospinal fluid (CSF) flow, leading to accumulations of ventricular CSF (e.g., obstructive hydrocephalus associated with a caudal fossa lesion).

Question 393

INFLAMMATORY, NONINFECTIOUS DISORDERS OF THE BRAIN: An important concept to remember is that these terms are based upon histopathologic descriptions, rather than known etiologies. The two most commonly recognized disorders in this disease category are?

Answer 393

Granulomatous meningoencephalomyelitis (GME) and necrotizing encephalitis (NE). The “umbrella” term meningoencephalitis of unknown etiology (MUE) has been suggested.[1]

Question 394

Granulomatous Meningoencephalomyelitis: Characteristic ................. cellular infiltrates of GME both define the disease syndrome and are responsible for the observed neurologic deficits. The underlying cause of this disease remains a mystery, but it is widely believed that GME is an ...........disorder, specifically a delayed-type (T cell–mediated) hypersensitivity reaction. Lesions predominate in the .............matter.

Answer 394

Characteristic perivascular cellular infiltrates of GME both define the disease syndrome and are responsible for the observed neurologic deficits. The underlying cause of this disease remains a mystery, but it is widely believed that GME is an autoimmune disorder, specifically a delayed-type (T cell–mediated) hypersensitivity reaction. Lesions predominate in the white matter.

Question 395

There are three recognized clinical forms of GME: which ones?

Answer 395

focal, multifocal (disseminated), and ocular. GME can affect any breed of dog of any age and either sex. However, young to middle-aged (median age of 5 years) female dogs of small breeds (e.g., poodles, terriers) appear to be predisposed. Seizures, cerebellovestibular dysfunction, and cervical hyperesthesia are common features of multifocal GME. Therapy: Glucocorticoid therapy A number of alternative immunosuppressive drugs have been evaluated as adjunctive treatment options for GME patients. The three most promising drug options include procarbazine, cytosine arabinoside, and cyclosporine.

Question 396

Does cyclosporine A readily cross the BBB? How can cyclosporine A work on patients affected by GME?

Answer 396

Cyclosporine (cyclosporine A) is a lipophilic peptide that does not readily cross the BBB. Despite this, it is thought that the drug may become trapped in endothelial cells in the CNS, and that the inflammatory nature of GME may allow more cyclosporine to cross the BBB than would occur in the absence of inflammation. The mode of action of cyclosporine is blocking of transcription of genes in activated T cells that lead to the production of inflammatory cytokines.

Question 397

How does procarbazine work?

Answer 397

Procarbazine is an antineoplastic drug that crosses the blood-brain barrier (BBB) and has some specificity for T cells.

Question 398

Necrotizing Encephalitis: This disease subcategory includes NME and NLE. These are suspected to be ......... disorders. Both necrotizing disorders are similar in that they are characterized by multiple cavitary necrotic nonsuppurative inflammatory brain lesions that involve ............ matter

Answer 398

these are suspected to be autoimmune disorders. Both necrotizing disorders are similar in that they are characterized by multiple cavitary necrotic nonsuppurative inflammatory brain lesions that involve both gray and white matter The same drug protocols used in recent years for GME have been suggested for use in cases of NE.

Question 399

Infectious brain disorders are far less commonly encountered in dogs and cats compared with noninfectious disorders. Commonly implicated organisms in canine and feline bacterial meningoencephalitis include?

Answer 399

Staphylococcus and Streptococcus species, Pasteurella multocida (especially cats), and others. In one report of canine bacterial meningoencephalitis, the most common causative organisms were Escherichia coli, Streptococcus species, and Klebsiella species. Gram-negative infections were most common, and single versus multiple organism infections were equally likely.[8]

Question 400

Appropriate antibiotics for bacterial meningoencephalitis should ideally be?

Answer 400

Bactericidal, have a low-level protein binding, and be able to cross the BBB. High intravenous doses of ampicillin (e.g., 22 mg/kg q6h) have been recommended as an appropriate therapeutic choice for most cases of canine and feline bacterial meningoencephalitis. Ampicillin crosses the inflamed BBB relatively well and is bactericidal. If a gram-negative infection is suspected or confirmed, enrofloxacin or a third-generation cephalosporin are good choices.

Question 401

Fungal Meningoencephalitis: There is a wide variety of fungal organisms that may invade the CNS: such as?

Answer 401

Cryptococcus, Coccidioides, Blastomyces, Histoplasma, Aspergillus, and the phaeohyphomycoses (e.g., Cladosporium). Cryptococcus neoformans is by far the most common fungal organism associated with meningoencephalitis in dogs and cats. With cryptococcosis, extraneural infection around the head region (eyes, nasal and frontal sinuses) is most likely. Few antifungal drugs are able to cross the BBB effectively, even when inflamed. Flucytosine (5-fluorocytosine) and the triazole drug fluconazole are two antifungal drugs that readily cross the BBB.

Question 402

Viral Meningoencephalitis: The most frequently encountered viral infections of the brain in dogs and cats in clinical practice are?

Answer 402

Canine distemper (paramyxovirus) virus and feline infectious peritonitis (FIP-coronavirus) virus, respectively. Other, less common causes of viral meningoencephalitides include rabies virus (dogs and cats), FIV (a lentivirus), canine herpesvirus, feline parvovirus (panleukopenia virus), feline Borna disease virus (BDV), pseudorabies (dogs and cats, caused by a porcine herpesvirus), and West Nile virus (a mosquito-borne flavivirus).

Question 403

Historical and clinical signs of systemic disease (e.g., fever, weight loss) are common in cats with coronavirus meningoencephalitis. Multifocal encephalopathy is common, often with ...................... and ........................dysfunction.

Answer 403

Multifocal encephalopathy is common, often with brainstem and cerebellar dysfunction.

Question 404

The typical “furious” and “paralytic” forms of rabies have been described. The furious form is more common in cats and is characterized by apprehension and aggression, suggesting primarily forebrain dysfunction. The paralytic form, encountered more frequently in dogs, is characterized by .......... motor neuron dysfunction of brainstem nuclei, leading to a dropped jaw (cranial nerve .........) and swallowing difficulty with attendant ptyalism (CNs ..........). Respiratory difficulty and gait abnormalities may also be apparent. Focal and/or generalized seizure activity may occur with either form of rabies. Dogs and cats with rabies may present with a wide variety of clinical signs of neurologic dysfunction, and the previously mentioned forms of rabies should be viewed as very rough guidelines.

Answer 404

The typical “furious” and “paralytic” forms of rabies have been described. The furious form is more common in cats and is characterized by apprehension and aggression, suggesting primarily forebrain dysfunction. The paralytic form, encountered more frequently in dogs, is characterized by lower motor neuron dysfunction of brainstem nuclei, leading to a dropped jaw (cranial nerve [CN] V) and swallowing difficulty with attendant ptyalism (CNs IX to XI). Respiratory difficulty and gait abnormalities may also be apparent. Focal and/or generalized seizure activity may occur with either form of rabies. Dogs and cats with rabies may present with a wide variety of clinical signs of neurologic dysfunction, and the previously mentioned forms of rabies should be viewed as very rough guidelines.

Question 405

Other infectious organisms that may lead to multifocal encephalopathy in dogs and cats include

Answer 405

rickettsial (e.g., ehrlichiosis, Rocky Mountain spotted fever [RMSF] in dogs), protozoal (e.g., Toxoplasma in dogs and cats, Neospora in dogs), and verminous (e.g., Cuterebra in cats) agents.

Question 406

Degenerative and Anomalous Disorders of the Brain: Degenerative brain disorders that may cause multifocal or diffuse encephalopathy are numerous and include?

Answer 406

Lysosomal storage diseases, mitochondrial encephalopathies, and organic acidurias. These categories of degenerative diseases are similar in that some metabolic defect is responsible for the development of intracranial disease.

Question 407

Degenerative and Anomalous Disorders of the Brain There are a number of anomalous brain disorders that can lead to multifocal or diffuse clinical signs of brain dysfunction. These include?

Answer 407

Caudal occipital malformation syndrome (COMS, also known as Chiari type I malformation and occipital bone hypoplasia), intracranial arachnoid cysts, and congenital hydrocephalus.

Question 408

Spinal cord diseases can be divided into two groups: which ones?

Answer 408

1. The first group comprises diseases that affect both the nervous system and other organ systems. 2. The second group includes diseases that are unique to the nervous system, such as disorders of myelin, neurons, or supporting cells (glial cells and the like). Categories of disease that may be included in either of these two groups are congenital and familial disorders, toxicities, nutritional disorders, degenerative diseases, neoplasia, and idiopathic disorders.

Question 409

Localization of function in the spinal cord causes a pathologic process to result in many different clinical presentations, depending on the part or parts of the spinal cord it affects. For example, a spinal cord neoplasm at the level of the C3 vertebra may result in .............., whereas the identical neoplasm at the level of the T13 vertebra may result in ..............., leaving the thoracic limbs unaffected.

Answer 409

For example, a spinal cord neoplasm at the level of the C3 vertebra may result in tetraparesis, whereas the identical neoplasm at the level of the T13 vertebra may result in paraparesis, leaving the thoracic limbs unaffected.

Question 410

Clinical syndromes that affect the spinal cord may be characterized by a single focal lesion (...............myelopathy) or by several focal lesions (................... disorders). Myelopathies may be ..........., meaning that spinal cord dysfunction occurs secondary to diseases of the vertebrae, meninges, or epidural space, or it may be ............, which means the disease begins as an intramedullary lesion. Extrinsic myelopathies are almost always transverse myelopathies.

Answer 410

Clinical syndromes that affect the spinal cord may be characterized by a single focal lesion (transverse myelopathy) or by several focal lesions (multifocal disorders). Myelopathies may be extrinsic, meaning that spinal cord dysfunction occurs secondary to diseases of the vertebrae, meninges, or epidural space, or it may be intrinsic, which means the disease begins as an intramedullary lesion. Extrinsic myelopathies are almost always transverse myelopathies.

Question 411

Five groups of clinical signs are seen to a varying degree in all animals with disease that affects the spinal cord: which ones?

Answer 411

Depression or loss of voluntary movement Alteration of spinal reflexes Changes in muscle tone Muscle atrophy Sensory dysfunction.

Question 412

Diseases of the spinal cord may also result in dysfunction of the bladder, urethral sphincter, and anal sphincter and in loss of voluntary control of urination and defecation. This may be due to interruption of spinal cord pathways connecting the .......... and .............. to the bladder and rectum that are important in normal ............ reflex function and voluntary control of ........... and ........., or it may be due to interruption of the ..................nerve supply to the bladder and urinary and anal sphincters (L7 to S3 spinal cord segments and spinal nerves).

Answer 412

Diseases of the spinal cord may also result in dysfunction of the bladder, urethral sphincter, and anal sphincter and in loss of voluntary control of urination and defecation. This may be due to interruption of spinal cord pathways connecting the brainstem and cerebrum to the bladder and rectum that are important in normal detrusor reflex function and voluntary control of micturition and defecation, or it may be due to interruption of the parasympathetic nerve supply to the bladder and urinary and anal sphincters (L7 to S3 spinal cord segments and spinal nerves). Spinal cord diseases also indirectly interfere with excretory functions by impairing the animal's ability to assume the posture necessary for normal defecation or urination.

Question 413

Voluntary Movement: Loss of voluntary movement as a result of interruption of motor pathways at any point from the cerebrum to the muscle fibers is referred to as .............. (plegia). Lesser degrees of motor loss are referred to as ................

Answer 413

Loss of voluntary movement as a result of interruption of motor pathways at any point from the cerebrum to the muscle fibers is referred to as paralysis (plegia). Lesser degrees of motor loss are referred to as paresis.

Question 414

Voluntary Movement: The terms tetraplegia (or quadriplegia) and tetraparesis (or quadriparesis) refer to?

Answer 414

An absence of voluntary movement in the thoracic and pelvic limbs and to depression of movement in the thoracic and pelvic limbs, respectively.

Question 415

Voluntary Movement: The terms paraplegia and paraparesis describe?

Answer 415

The absence of voluntary movement and depression of voluntary movement in only the pelvic limbs.

Question 416

Hemiplegia and hemiparesis refer to?

Answer 416

Paralysis or motor dysfunction, respectively, of a pelvic limb and a thoracic limb on the same side.

Question 417

Ataxia (incoordination) is seen in association with paresis and probably occurs as a result of interference with both the.................. and ................. spinal cord pathways.

Answer 417

Ataxia (incoordination) is seen in association with paresis and probably occurs as a result of interference with both the ascending and descending spinal cord pathways. Many ascending spinal cord tracts contribute to the transmission of sensory information to the cerebrum for coordination of voluntary movements. Observation of gait is the only clinical testing technique for assessing these pathways.

Question 418

Spinal Reflexes: do they occur independent of brain input?

Answer 418

Spinal reflexes are stereotyped involuntary actions that occur independent of brain input and that may be elicited consistently by specific stimuli.

Question 419

Where are the central nervous system (CNS) components of spinal reflex arcs located?

Answer 419

The central nervous system (CNS) components of spinal reflex arcs are located entirely in the spinal cord.

Question 420

Disturbance of spinal reflexes occurs in almost all animals with spinal cord disease. A spinal reflex may be normal, depressed (..............), absent (..............), or exaggerated (...................).

Answer 420

Disturbance of spinal reflexes occurs in almost all animals with spinal cord disease. A spinal reflex may be normal, depressed (hyporeflexia), absent (areflexia), or exaggerated (hyperreflexia). Classification of spinal reflexes into one of these categories is helpful for localizing a spinal cord lesion.

Question 421

Depression of a spinal reflex in association with spinal cord disease most frequently occurs as a result of involvement by a pathologic process of which spinal cord segments?

Answer 421

The spinal cord segments that mediate the reflex. It must be remembered that involvement of motor nerves arising from or of sensory nerves traveling to such spinal cord segments, or abnormalities of the effector organ (muscle), may also result in depression of spinal reflexes.

Question 422

Exaggeration of a spinal reflex in association with spinal cord disease occurs when a lesion affects the spinal cord .......... to segments that mediate a reflex. The concept that reflex exaggeration simply results from interruption of ......................inhibitory pathways is useful for lesion localization; however, other factors are likely to be involved. Exaggeration of a reflex may result from a ...........lesion, as well as from a .....................lesion.

Answer 422

Exaggeration of a spinal reflex in association with spinal cord disease occurs when a lesion affects the spinal cord cranial to segments that mediate a reflex. The concept that reflex exaggeration simply results from interruption of descending inhibitory pathways is useful for lesion localization; however, other factors are likely to be involved. Exaggeration of a reflex may result from a brain lesion, as well as from a spinal cord lesion.

Question 423

Spinal cord lesions that affect both gray and white matter may result in ................. of spinal reflexes mediated by spinal cord segments involved in a pathologic process and in ................... of spinal cord reflexes mediated by spinal cord segments caudal to a lesion. This is useful for lesion localization, particularly lesions that affect the cervical enlargement (C.... to T.... spinal cord segments), where thoracic limb hyporeflexia and pelvic limb hyperreflexia may be present.

Answer 423

Spinal cord lesions that affect both gray and white matter may result in depression of spinal reflexes mediated by spinal cord segments involved in a pathologic process and in exaggeration of spinal cord reflexes mediated by spinal cord segments caudal to a lesion. This is useful for lesion localization, particularly lesions that affect the cervical enlargement (C6 to T2 spinal cord segments), where thoracic limb hyporeflexia and pelvic limb hyperreflexia may be present.

Question 424

Interpretation of reflex abnormalities must be approached with the knowledge that two (or more) lesions in the same anatomic division of the spinal cord may produce reflex changes identical to those seen with a single lesion. For example, two lesions between the T........ and L...... spinal cord segments cause .........reflexia in the pelvic limbs indistinguishable from that resulting from a solitary lesion in this location. Furthermore, hyporeflexia produced by one spinal cord lesion may mask hyperreflexia that would otherwise result from a second lesion in a more cranial location. For example, a lesion in the lumbar enlargement (L..... to S...... spinal cord segments) causes .........reflexia in the pelvic limbs that masks the hyperreflexia that otherwise would result from a second lesion cranial to the L4 spinal cord segment.

Answer 424

Interpretation of reflex abnormalities must be approached with the knowledge that two (or more) lesions in the same anatomic division of the spinal cord may produce reflex changes identical to those seen with a single lesion. For example, two lesions between the T3 and L3 spinal cord segments cause hyperreflexia in the pelvic limbs indistinguishable from that resulting from a solitary lesion in this location. Furthermore, hyporeflexia produced by one spinal cord lesion may mask hyperreflexia that would otherwise result from a second lesion in a more cranial location. For example, a lesion in the lumbar enlargement (L4 to S3 spinal cord segments) causes hyporeflexia in the pelvic limbs that masks the hyperreflexia that otherwise would result from a second lesion cranial to the L4 spinal cord segment.

Question 425

What is a spinal chock?

Answer 425

=Depression of spinal reflexes caudal to a lesion. Spinal shock may occur in quadrupeds; however, it is too brief to be of clinical significance. Hyporeflexia observed immediately after spinal cord injury should be attributed to damage to spinal cord segments that mediate the reflexes or to other systemic complications (e.g., hypovolemic shock) that frequently accompany spinal cord trauma.

Question 426

Muscle Tone: Maintenance of normal muscle tone is a function of spinal reflexes (tonic muscle stretch reflexes). Alterations in muscle tone therefore are interpreted in a fashion similar to that for alterations in spinal reflexes described earlier. Abnormal muscle tone may be depressed (..............), absent (............), or exaggerated (...................), depending on the location of the spinal cord lesion.

Answer 426

Abnormal muscle tone may be depressed (hypotonia), absent (atonia), or exaggerated (hypertonia), depending on the location of the spinal cord lesion.

Question 427

Muscle Atrophy: Two types of muscle atrophy may occur in association with a spinal cord disease. Which ones?

Answer 427

Denervation atrophy is seen when the LMNs innervating a muscle are damaged by a lesion that affects their spinal cord segment or segments of origin. Disuse atrophy may be seen in muscles innervated by LMNs caudal to a spinal cord lesion. Disuse atrophy commonly is slower in onset and progression than denervation atrophy, most often is less severe.

Question 428

Sensory Dysfunction: Abnormalities of sensory (ascending) pathways of the spinal cord contribute to the ataxia of spinal cord disease; Does a specific clinical test of their function exist?

Answer 428

Specific clinical tests of their function do not exist. Perception in animals must be inferred from certain behavioral responses that indicate that ascending sensory signals have reached the cerebral cortex (e.g., aversive response to a noxious stimulus). Interruption of sensory signals at any point between (and including) sensory receptors in the periphery and cerebral cortex may depress or obliterate normal sensory function.

Question 429

Proprioceptive positioning (perception of ....................) and pain perception are tested during a neurologic examination. Proprioceptive positioning is a sensitive indicator of .......................function, and depression or loss of proprioceptive positioning frequently is the sign first caused by a myelopathy.

Answer 429

Proprioceptive positioning (perception of body position or movement) and pain perception are tested during a neurologic examination. Proprioceptive positioning is a sensitive indicator of spinal cord function, and depression or loss of proprioceptive positioning frequently is the sign first caused by a myelopathy.

Question 430

Pain perception may be normal, depressed (hypesthesia), absent (anesthesia), or exaggerated (hyperesthesia). Two types of pain perception may be distinguished in animals. Which ones

Answer 430

Cutaneous (“superficial”) pain perception is manifested by a response to pricking or pinching of the skin Deep pain perception is manifested by reaction to pinching of the toes or tail across bone with hemostatic forceps.

Question 431

Areas of decreased or absent cutaneous pain perception may aid the identification of specific nerves, nerve roots, and spinal cord segments involved in a pathologic process. This technique of cutaneous mapping is especially useful with lesions that affect the cervical or lumbar enlargements. .............. pain perception appears to be the sensory function most resistant to a spinal cord disease, and it is the last spinal cord function to disappear in myelopathies of any type. An animal with complete bilateral loss of .......... pain perception due to a transverse myelopathy is necessarily paralyzed ............. to the lesion. Loss of .........pain perception, therefore, is a grave prognostic sign.

Answer 431

Deep pain perception appears to be the sensory function most resistant to a spinal cord disease, and it is the last spinal cord function to disappear in myelopathies of any type. An animal with complete bilateral loss of deep pain perception due to a transverse myelopathy is necessarily paralyzed caudal to the lesion. Loss of deep pain perception, therefore, is a grave prognostic sign.

Question 432

Hyperesthesia in association with a spinal cord disease may indicate nerve root or ........... nerve involvement, or it may be consistent with .......... irritation. A focal area of hyperesthesia over the vertebral column may indicate the location of a spinal cord lesion.

Answer 432

Hyperesthesia in association with a spinal cord disease may indicate nerve root or spinal nerve involvement, or it may be consistent with meningeal irritation. A focal area of hyperesthesia over the vertebral column may indicate the location of a spinal cord lesion.

Question 433

LOCALIZATION OF SPINAL CORD DISEASES: Motor, sensory, reflex, and sphincter abnormalities may help determine the location of a lesion in one of four major longitudinal divisions of the spinal cord: which ones?

Answer 433

The cervical region (C1 to C5 spinal cord segments), the cervical enlargement (C6 to T2), the thoracolumbar region (T3 to L3), the lumbar enlargement (L4 to Cd5). It is essential to remember that these divisions refer to spinal cord segments, not vertebrae, and that spinal cord segments do not correspond exactly with vertebrae of the same number. Some variations may be encountered because of slight differences among animals in segments that form the cervical and lumbar enlargements.

Question 434

Cervical Enlargement (C6 to T2 Spinal Cord Segments): Ataxia and paresis of ............. limbs usually are present with lesions of the cervical enlargement. Occasionally ........ of the thoracic limbs and ............of the pelvic limbs may be seen. Spinal reflexes and muscle tone may be normal or .................. in the thoracic limbs and normal or ............in the pelvic limbs. The panniculus reflex may be ................or ...............unilaterally or bilaterally as a result of interruption of the LMNs involved in this reflex (C8 and T1 spinal cord segments). If bladder dysfunction occurs, it is similar to that observed with a lesion in the cervical region, with .......................urination. Anal reflexes and anal tone most often are normal, although voluntary control of defecation may be absent. Unilateral Horner's syndrome is commonly observed with a spinal cord lesion of the cervical enlargement, particularly a lesion involving the .........to .......... spinal cord segments or nerve roots. Proprioceptive positioning and other postural reactions usually are ................ in all four limbs. Alterations in these functions may be more pronounced in the .........limbs than the ............. limbs. Severe depression or loss of pain perception rarely is seen in association with a lesion of the cervical enlargement, except in .................. myelopathies (e.g., ischemic myelopathy). Hyperesthesia at the level of a lesion of the cervical enlargement, thoracic limb lameness, or apparent neck pain may be seen.

Answer 434

Ataxia and paresis of all four limbs usually are present with lesions of the cervical enlargement. Occasionally paresis of the thoracic limbs and paralysis of the pelvic limbs may be seen. Spinal reflexes and muscle tone may be normal or decreased in the thoracic limbs and normal or exaggerated in the pelvic limbs. The panniculus reflex may be depressed or absent unilaterally or bilaterally as a result of interruption of the LMNs involved in this reflex (C8 and T1 spinal cord segments). If bladder dysfunction occurs, it is similar to that observed with a lesion in the cervical region, with loss of voluntary control of urination. Anal reflexes and anal tone most often are normal, although voluntary control of defecation may be absent. Unilateral Horner's syndrome is commonly observed with a spinal cord lesion of the cervical enlargement, particularly a lesion involving the Tl to T3 spinal cord segments or nerve roots. Proprioceptive positioning and other postural reactions usually are depressed in all four limbs. Alterations in these functions may be more pronounced in the pelvic limbs than the thoracic limbs. Occasionally, proprioceptive positioning is absent only in a thoracic and pelvic limb on the same side. Severe depression or loss of pain perception rarely is seen in association with a lesion of the cervical enlargement, except in intrinsic myelopathies (e.g., ischemic myelopathy). Hyperesthesia at the level of a lesion of the cervical enlargement, thoracic limb lameness, or apparent neck pain may be seen.

Question 435

Thoracolumbar Region (T3 to L3 Spinal Cord Segments) Most spinal cord lesions of dogs or cats occur in the thoracolumbar region. Typically the thoracic limb gait is ........., and ............ and ........ or .........., is seen in the pelvic limbs. The thoracic limb spinal reflexes are normal. Pelvic limb spinal reflexes and muscle tone are normal to ................., depending on the severity of the lesion. Muscle atrophy is not seen in the thoracic limbs. Pelvic limb muscle atrophy, if present, is the result of disuse and is seen in animals with a severe, chronic lesion. Anal reflexes and anal tone usually are normal or ................. Voluntary control of defecation may be lost. (Reflex defecation occurs when the rectum is filled with feces; however, it may not be at an appropriate time or place) The degree of bladder dysfunction varies, depending on the severity of the spinal cord lesion. There may be loss of voluntary control of urination, detrusor muscle areflexia with normal or increased urinary sphincter tone, or reflex dyssynergia, in which initiation of voiding occurs and is stopped by involuntary contraction of the urethral sphincter. Proprioceptive positioning and other postural reactions are ............ in the thoracic limbs and .................... in the pelvic limbs. Pain perception is ......... in the thoracic limbs and may be ..................,......,.......... in the pelvic limbs. The panniculus reflex may be reduced or absent caudal to a lesion. In the lumbar region, the panniculus reflex may be present in lesions caudal to L3 as a result of the pattern of cutaneous innervation of lumbar spinal nerves.[1] There may be an area of hyperesthesia at the level of a lesion. The Schiff-Sherrington sign may be seen with a lesion in the thoracolumbar region. It usually is an indication of an acute, severe spinal cord lesion, although such a lesion may be reversible.

Answer 435

Thoracolumbar Region (T3 to L3 Spinal Cord Segments) Most spinal cord lesions of dogs or cats occur in the thoracolumbar region. Typically the thoracic limb gait is normal, and paresis and ataxia, or paralysis, is seen in the pelvic limbs. The thoracic limb spinal reflexes are normal. Pelvic limb spinal reflexes and muscle tone are normal to exaggerated, depending on the severity of the lesion. Muscle atrophy is not seen in the thoracic limbs. Pelvic limb muscle atrophy, if present, is the result of disuse and is seen in animals with a severe, chronic lesion. Anal reflexes and anal tone usually are normal or exaggerated. Voluntary control of defecation may be lost. Reflex defecation occurs when the rectum is filled with feces; however, it may not be at an appropriate time or place. The degree of bladder dysfunction varies, depending on the severity of the spinal cord lesion. There may be loss of voluntary control of urination, detrusor muscle areflexia with normal or increased urinary sphincter tone, or reflex dyssynergia, in which initiation of voiding occurs and is stopped by involuntary contraction of the urethral sphincter. The bladder can be manually expressed in some animals, but not others, as a result of increased tone of the urinary bladder sphincter; this is often referred to as a UMN bladder. Although “overflow” incontinence may occur with lesions of the spinal cord in this region, secondary to overfilling of the bladder, detrusor muscle tone and urinary sphincter tone are present, which distinguishes this type of incontinence from that due to lesions of the lumbar enlargement and cauda equina (LMN bladder). Proprioceptive positioning and other postural reactions are normal in the thoracic limbs and depressed or absent in the pelvic limbs. Pain perception is normal in the thoracic limbs and may be normal, depressed, or absent in the pelvic limbs. The panniculus reflex may be reduced or absent caudal to a lesion. In the lumbar region, the panniculus reflex may be present in lesions caudal to L3 as a result of the pattern of cutaneous innervation of lumbar spinal nerves.[1] There may be an area of hyperesthesia at the level of a lesion. The Schiff-Sherrington sign may be seen with a lesion in the thoracolumbar region. It usually is an indication of an acute, severe spinal cord lesion, although such a lesion may be reversible.

Question 436

Lumbar Enlargement (L4 to Cd5 Spinal Cord Segments) and Cauda Equina Involvement of the lumbar enlargement and cauda equina by a pathologic process results in varying degrees of pelvic limb paresis and ataxia, or paralysis, and is often accompanied by dysfunction of the bladder and by paresis or paralysis of the anal sphincter and tail. Thoracic limb function is .......... Pelvic limb reflexes and muscle tone are ............. or .............. Muscle atrophy often is present in the pelvic limbs. Conscious proprioception and other postural reactions may be ............... or ............. in the pelvic limbs. Anal tone and anal reflexes are ............. or .............. The rectum and colon may become distended with feces, and fecal incontinence, with continual leakage of feces, is often seen. Constipation may result from the inability to void feces. ............... or ........ of the urethral sphincters and detrusor muscle results in overfilling of the bladder and “overflow” incontinence. Affected animals have a large residual volume of urine in the bladder, and the bladder is easily expressed manually (...MN bladder). The Schiff-Sherrington sign occasionally may be seen with an acute lesion that affects this region of the spinal cord.

Answer 436

Lumbar Enlargement (L4 to Cd5 Spinal Cord Segments) and Cauda Equina Involvement of the lumbar enlargement and cauda equina by a pathologic process results in varying degrees of pelvic limb paresis and ataxia, or paralysis, and is often accompanied by dysfunction of the bladder and by paresis or paralysis of the anal sphincter and tail. Thoracic limb function is normal. Pelvic limb reflexes and muscle tone are reduced or absent. Muscle atrophy often is present in the pelvic limbs. Conscious proprioception and other postural reactions may be reduced or absent in the pelvic limbs. Anal tone and anal reflexes are reduced or absent. The rectum and colon may become distended with feces, and fecal incontinence, with continual leakage of feces, is often seen. Constipation may result from the inability to void feces. Paresis or paralysis of the urethral sphincters and detrusor muscle results in overfilling of the bladder and “overflow” incontinence. Affected animals have a large residual volume of urine in the bladder, and the bladder is easily expressed manually (LMN bladder). The Schiff-Sherrington sign occasionally may be seen with an acute lesion that affects this region of the spinal cord.

Question 437

The term cauda equina is used to describe?

Answer 437

The lumbar, sacral, and caudal nerve roots and spinal nerves as they extend caudally from the caudal tip (conus medullaris) of the spinal cord in the vertebral canal. Lesions that affect the cauda equina result in clinical signs that are indistinguishable from those produced by lesions affecting the spinal cord segments from which the nerves of the cauda equina arise (L6 to Cd5).

Question 438

Meningitis may be accompanied by infection of the underlying parenchyma of the spinal cord (.........).

Answer 438

Meningitis may be accompanied by infection of the underlying parenchyma of the spinal cord (myelitis).

Question 439

Pathologically, meningitis is characterized by infiltration of inflammatory cells into the ............. Inflammation may occur throughout the entire subarachnoid space of the brain and ................. Myelitis is characterized by necrosis and infiltration of inflammatory cells into the ......................

Answer 439

Pathologically, meningitis is characterized by infiltration of inflammatory cells into the leptomeninges. Inflammation may occur throughout the entire subarachnoid space of the brain and spinal cord. Myelitis is characterized by necrosis and infiltration of inflammatory cells into the spinal cord parenchyma.

Question 440

Ex of bacteria that have been isolated from cats or dogs with meningitis and myelitis?

Answer 440

Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus albus, and Pasteurella, Actinomyces, and Nocardia spp.

Question 441

Ex of fungal infections that have been isolated from cats or dogs with meningitis and myelitis?

Answer 441

Cryptococcus neoformans, Blastomyces dermatitidis, Histoplasma capsulatum, and Coccidioides immitis. C. neoformans is found ubiquitously and frequently causes infection in immunosuppressed animals. Cryptococcosis is more common in cats than in dogs, and infection may result from extension of nasal infection through the cribriform plate.

Question 442

Rickettsial or protothecal infections may cause meningomyelitis similar in clinical presentation to that resulting from bacterial or fungal infection of the CNS. ..............(............infection) and Rocky Mountain spotted fever ([RMSF] caused by Rickettsia rickettsii) may cause meningo-encephalitis or meningomyelitis in dogs.

Answer 442

Rickettsial or protothecal infections may cause meningomyelitis similar in clinical presentation to that resulting from bacterial or fungal infection of the CNS. Ehrlichiosis (Ehrlichia canis infection) and Rocky Mountain spotted fever ([RMSF] caused by Rickettsia rickettsii) may cause meningo-encephalitis or meningomyelitis in dogs.

Question 443

Bacterial or Fungal Infections Clinical signs of meningitis include?

Answer 443

Apparent spinal pain, hyperesthesia, and cervical or thoracolumbar rigidity, occasionally manifested as a “sawhorse” posture. Irritation of the numerous nerve endings in the meninges results in reflex muscle spasms when affected animals are stimulated. Fever is intermittent and is more likely to occur in association with concurrent bacteremia or disseminated fungal infection. Fever may occur in association with primary CNS infections as a result of leukocytic pyrogens in the CSF or hypothalamic circulation. Neurologic deficits are indicative of associated myelitis or radiculitis, and abnormalities depend on the location and extent of infection. Focal myelitis may result in signs of

Question 444

Are the clinical signs of bacterial or fungal meningitis and myelitis in animals distinguishable from those of other causes of meningitis and myelitis?

Answer 444

The clinical signs of bacterial or fungal meningitis and myelitis in animals are indistinguishable from those of other causes of meningitis and myelitis, such as granulomatous meningoencephalitis and corticosteroid-responsive meningitis; necrotizing vasculitis of the meningeal arteries and distemper virus myelitis in dogs; and CNS toxoplasmosis and FIP meningomyelitis in cats.

Question 445

Bacterial Infections In the treatment of bacterial meningitis and/or myelitis, it is desirable to use an antimicrobial that is specific for the causative organism and that crosses the blood-brain barrier (or the blood–spinal cord barrier) in therapeutic concentrations so that drug concentrations may be maintained after the acute phase of inflammation has subsided. The blood-brain, blood–spinal cord, and blood–spinal fluid barriers are most permeable to antimicrobials with high................. solubility, .............. ionization potential, and ........... protein-binding affinity.

Answer 445

The blood-brain, blood–spinal cord, and blood–spinal fluid barriers are most permeable to antimicrobials with high lipid solubility, low ionization potential, and low protein-binding affinity. High-dose intravenous therapy with a bactericidal drug should be used when possible, although many bactericidal drugs penetrate the CSF poorly. Penicillin and penicillin derivatives in high doses have been recommended for the treatment of CNS infections caused by gram-positive cocci

Question 446

Can cephalosporins reach effective CNS concentrations?

Answer 446

Most cephalosporins penetrate the CNS poorly.[48] Several third-generation cephalosporins (e.g., cefotaxime) reach effective CNS concentrations and are considered the drugs best suited for treatment of gram-negative meningitis. First- and second-generation cephalosporins do not reach effective CSF concentrations and should not be used in the treatment of CNS infections.

Question 447

Is metronidazole useful for the treatment of most anaerobic infections in the CNS? Which signs of toxicity has been reported in dogs?

Answer 447

Metronidazole is useful for the treatment of most anaerobic infections, is bactericidal, and diffuses well into all tissues, including the CNS. Toxicity (central vestibular signs and cerebellar dysfunction) has been reported in dogs treated with metronidazole.

Question 448

Is cholaramphenicol bacteriostatic or bactericidal?

Answer 448

Chloramphenicol reaches higher CSF concentrations than most other antibiotics; however, it is bacteriostatic, and many Staphylococcus strains have been shown to be resistant to this drug.

Question 449

Can sulfonamides penetrate the CSF effectively?

Answer 449

Most sulfonamides penetrate the CSF effectively.

Question 450

Cervical Spondylomyelopathy: Several terms have been used to describe this disease of the cervical vertebral column of Great Danes, Doberman Pinschers, and other large-breed dogs. The term cervical spondylomyelopathy accurately reflects the complexity of the syndrome and therefore has become widely accepted. The C5-C6 and C6-C7 vertebrae and disks appear to be affected most commonly, although alterations consistent with a diagnosis of cervical spondylomyelopathy may be seen at the level of C4-C5 and less frequently at C3-C4. These terms include wobbler syndrome, caudal cervical malformation-malarticulation, cervical spondylopathy, cervical vertebral instability, and cervical vertebral stenosis. The term wobbler is nonspecific; it describes a dog with which clinical signs?

Answer 450

The clinical signs reflect chronic compression of the cervical spinal cord. Generalized ataxia and tetraparesis that may be seen with a variety of cervical myelopathies. Neurologic abnormalities that may be noted in the pelvic limbs include depression or loss of proprioceptive positioning reactions and exaggerated spinal reflexes. Thoracic limb abnormalities most often occur after the development of neurologic deficits in the pelvic limbs, and thoracic limb deficits seldom progress to the level of severity of the pelvic limb abnormalities.

Question 451

Corticosteroid-responsive meningitis-arteritis, which occurs in young, medium- to large-breed dogs, may be the most frequently occurring form of meningitis. The etiology is unknown; however, immunopathologic mechanisms are suspected because ........ seems to play a central role in the pathogenesis.

Answer 451

Corticosteroid-responsive meningitis-arteritis, which occurs in young, medium- to large-breed dogs, may be the most frequently occurring form of meningitis. The etiology is unknown; however, immunopathologic mechanisms are suspected because IgA seems to play a central role in the pathogenesis. Clinical signs include reluctance to move, arched back, stiff gait, apparent cervical and/or thoracolumbar pain, fever, muscle rigidity or spasms, apparent pain on opening the mouth and, less commonly, neurologic deficits, such as decreased proprioceptive positioning, paraparesis, or tetraparesis. The clinical signs are indistinguishable from those of meningitis and myelitis of other causes (bacterial, fungal, viral) and from necrotizing vasculitis of spinal meningeal arteries.

Question 452

Degenerative myelopathy is characterized by slowly progressive ataxia and paresis of the ........limbs. Histologically, demyelination, axonal degeneration, and astrocytosis in the .......matter of the spinal cord are seen. The etiology of degenerative myelopathy is unknown in dogs.

Answer 452

Degenerative myelopathy is characterized by slowly progressive ataxia and paresis of the pelvic limbs. Histologically, demyelination, axonal degeneration, and astrocytosis in the white matter of the spinal cord are seen. These changes are found throughout the spinal cord and are most severe in the thoracic spinal cord segments. The etiology of degenerative myelopathy is unknown in dogs. It has been reported most commonly in German Shepherd Dogs. Affected dogs usually have a slowly progressive paraparesis and pelvic limb ataxia.

Question 453

Bacterial or fungal infection of the intervertebral disks and adjacent vertebral bodies (...............) or of only the vertebral bodies (.............) may cause extradural spinal cord or cauda equina compression as a result of granulation tissue, bony proliferation, or pathologic fracture or luxation.

Answer 453

Bacterial or fungal infection of the intervertebral disks and adjacent vertebral bodies (discospondylitis) or of only the vertebral bodies (spondylitis) may cause extradural spinal cord or cauda equina compression as a result of granulation tissue, bony proliferation, or pathologic fracture or luxation. These conditions result from implantation of bacteria or fungi introduced by migrating plant awns (grass seeds, foxtails), hematogenous spread, extension of a paravertebral infection, a penetrating wound, or previous disk or vertebral surgery. Affected intervertebral disks may show evidence of degeneration (collapsed disk space, spondylosis deformans) or trauma (traumatic disk protrusion, vertebral luxation).

Question 454

.............. virus is a neurotropic virus that may cause focal or diffuse demyelination in both gray and white matter of the CNS. The mechanism by which demyelination occurs is not known. The ........... matter of the cerebellum, cerebellar peduncles, optic nerves, optic tracts, and spinal cord are most severely affected.

Answer 454

Canine distemper (CD) virus is a neurotropic virus that may cause focal or diffuse demyelination in both gray and white matter of the CNS. The mechanism by which demyelination occurs is not known. The white matter of the cerebellum, cerebellar peduncles, optic nerves, optic tracts, and spinal cord are most severely affected.

Question 455

Distemper Myoclonus: Myoclonus, the ................ of a muscle or muscle group, is most often associated with CD infection. Any muscles may be involved, including the facial and masticatory muscles or the limb muscles. The pathogenesis of myoclonus is unknown

Answer 455

Distemper Myoclonus Myoclonus, the rhythmic twitching of a muscle or muscle group, is most often associated with CD infection. Any muscles may be involved, including the facial and masticatory muscles or the limb muscles. The pathogenesis of myoclonus is unknown

Question 456

FIP is a serious, almost always fatal disease caused by a coronavirus. Pyogranulomatous ............. and ........... may occur in cats with FIP. Meningeal and spinal cord lesions are probably the result of immune complex-mediated ............. Involvement of the CNS is more frequently observed in the .................... (.........) form than in the ........(..........) form of the disease.

Answer 456

FIP is a serious, almost always fatal disease caused by a coronavirus. Pyogranulomatous meningitis and myelitis may occur in cats with FIP. Meningeal and spinal cord lesions are probably the result of immune complex-mediated vasculitis. Involvement of the CNS is more frequently observed in the noneffusive (dry) form than in the effusive (wet) form of the disease. Focal, multifocal, or diffuse involvement of the spinal cord, brain, and meninges may occur with FIP, and clinical signs reflect the location of these lesions. The most commonly recognized neurologic signs are pelvic limb ataxia, hyperesthesia (especially over the back), and generalized ataxia. Affected animals usually manifest other clinical signs indicative of disseminated disease, such as persistent fever, weight loss, enlarged kidneys, chorioretinitis, panophthalmitis, or anterior uveitis.

Question 457

Intramedullary, intrameningeal, or epidural hemorrhage may be due to coagulopathies; including...? And in association with...?

Answer 457

Thrombocytopenia, clotting factor deficiencies, disseminated intravascular coagulation, and anticoagulant poisonings (e.g., warfarin). Acute hemorrhage may also occur in association with tumors, vascular malformations, acute intervertebral disk protrusion, trauma, parasitic migration, or meningitis. Spontaneous hemorrhage may occur Extensive gray matter necrosis may occur with intramedullary hemorrhage, resulting in LMN signs over a relatively large area of the spinal cord, especially if the cervical or lumbosacral spinal cord is involved.

Question 458

Hypervitaminosis A in cats is characterized by extensive, confluent exostosis that is most prominent in the ............and ......... spine. It is caused by a chronic excess of dietary vitamin A and is usually a result of feeding of a diet consisting largely of ......... Exostosis may extend to involve the entire spine, ribs, and pelvic and thoracic limbs, with complete fusion of the spine and joints. Compression of spinal nerve roots or nerves may occur if new bone formation extends into the intervertebral foramina.

Answer 458

Hypervitaminosis A in cats is characterized by extensive, confluent exostosis that is most prominent in the cervical and thoracic spine.It is caused by a chronic excess of dietary vitamin A and is usually a result of feeding of a diet consisting largely of liver. Exostosis may extend to involve the entire spine, ribs, and pelvic and thoracic limbs, with complete fusion of the spine and joints. Compression of spinal nerve roots or nerves may occur if new bone formation extends into the intervertebral foramina. Clinical signs in affected cats include apparent cervical pain and rigidity, thoracic limb lameness, ataxia, reluctance to move, paralysis, and hyperesthesia or anesthesia of the skin of the neck and forelimbs.

Question 459

Degeneration of intervertebral disks may result in protrusion or extrusion of disk material into the spinal canal, causing spinal cord compression and clinical signs ranging from apparent pain to complete transverse myelopathy. Degenerative changes may occur in any of the intervertebral disks; however, they occur most commonly in the cervical, caudal thoracic, and lumbar spine. Because the intervertebral disks between .... and ......are stabilized dorsally by the intercapital ligaments, disk protrusion or extrusion is less likely in this region

Answer 459

Because the intervertebral disks between T1 and T11 are stabilized dorsally by the intercapital ligaments, disk protrusion or extrusion is less likely in this region.

Question 460

Type I disk herniation occurs with degeneration and rupture of the................... fibrosus and extrusion of the ....................... into the spinal canal. Type I disk extrusion is most commonly associated with chondroid disk degeneration. Although chondroid disk degeneration and type I disk extrusion occur most commonly in chondrodystrophoid breeds (Dachshund, Beagle, Pekingese, Lhasa Apso, Shih Tzu) and in breeds with chondrodystrophoid tendencies (Miniature Poodle and Cocker Spaniel), these conditions may occur in any breed, including large breeds.

Answer 460

Type I disk herniation occurs with degeneration and rupture of the dorsal anulus fibrosus and extrusion of the nucleus pulposus into the spinal canal. Type I disk extrusion is most commonly associated with chondroid disk degeneration (Web Figure 262-9). Although chondroid disk degeneration and type I disk extrusion occur most commonly in chondrodystrophoid breeds (Dachshund, Beagle, Pekingese, Lhasa Apso, Shih Tzu) and in breeds with chondrodystrophoid tendencies (Miniature Poodle and Cocker Spaniel), these conditions may occur in any breed, including large breeds.

Question 461

Type II disk protrusion is characterized by ............................ Type II disk protrusion is most commonly associated with .............disk degeneration.

Answer 461

Type II disk protrusion is characterized by bulging of the intervertebral disk without complete rupture of the anulus fibrosus. Type II disk protrusion is most commonly associated with fibroid disk degeneration.

Question 462

Chondroid degeneration of disks is characterized by an increase in the .............. content of the disk, alteration of the specific.................... concentration of the nucleus pulposus, and a decrease in the ................. content of the disk. The normally gelatinous nucleus pulposus becomes progressively more cartilaginous and granular and eventually may mineralize (calcify). Extrusion of degenerative nucleus pulposus occurs through fissures in or rupture of the anulus fibrosus.

Answer 462

Chondroid degeneration of disks is characterized by an increase in the collagen content of the disk, alteration of the specific glycosaminoglycan concentration of the nucleus pulposus, and a decrease in the water content of the disk. The normally gelatinous nucleus pulposus becomes progressively more cartilaginous and granular and eventually may mineralize (calcify). Extrusion of degenerative nucleus pulposus occurs through fissures in or rupture of the anulus fibrosus. In chondrodystrophoid breeds of dog, 75% to 100% of all disks undergo chondroid metaplasia by 1 year of age

Question 463

Fibroid disk degeneration occurs in older dogs of all breeds; however, it is most often recognized as a clinical problem in older, large-breed, ...................... dogs and is characterized by ................. metaplasia of the nucleus pulposus. An increase in the non collagenous ................protein content of the intervertebral disks occurs in nonchondrodystrophoid breeds with aging. Calcification of the disk may occur but is rare. Protrusion of the disk occurs, with a bulging of the anulus fibrosus as a result of partial rupture of the anular bands. Rupture of the anulus fibrosus and extrusion of the nucleus pulposus (characteristic of type I disk extrusion) infrequently is seen in association with type II disk protrusion.

Answer 463

Fibroid disk degeneration occurs in older dogs of all breeds; however, it is most often recognized as a clinical problem in older, large-breed, nonchondrodystrophoid dogs and is characterized by fibrous metaplasia of the nucleus pulposus. An increase in the noncollagenous glycoprotein content of the intervertebral disks occurs in nonchondrodystrophoid breeds with aging. Calcification of the disk may occur but is rare. Protrusion of the disk occurs, with a bulging of the anulus fibrosus as a result of partial rupture of the anular bands. Rupture of the anulus fibrosus and extrusion of the nucleus pulposus (characteristic of type I disk extrusion) infrequently is seen in association with type II disk protrusion.

Question 464

Intervertebral disk protrusion or extrusion may occur in .............................direction. In most instances only dorsal protrusions or extrusions are of clinical significance because meningeal irritation and nerve root and/or spinal cord compression may occur. The cause of intervertebral disk degeneration is unknown. Disk extrusions are most common in the cervical and T..... to L......... regions of the vertebral column.

Answer 464

Intervertebral disk protrusion or extrusion may occur in a ventral, dorsal, or lateral direction. In most instances only dorsal protrusions or extrusions are of clinical significance because meningeal irritation and nerve root and/or spinal cord compression may occur. The cause of intervertebral disk degeneration is unknown. Disk extrusions are most common in the cervical and T11 to L3 regions of the vertebral column.

Question 465

Does type 1 disk extrusion of type II extrusion usually results in more severe clinical signs than type I?

Answer 465

No, type I disk extrusion often results in more severe clinical signs than type II protrusion, although the mechanical distortion and compression of the spinal cord caused by type II protrusion may be greater. The nucleus pulposus is most often extruded into the spinal canal acutely (minutes to hours) or subacutely (days) from disks undergoing chondroid degeneration, whereas slowly progressive spinal cord compression most often accompanies protrusion of disks undergoing fibroid degeneration, as the bulging fibrous mass increasingly enlarges within the spinal canal. The spinal cord changes seen in acute versus chronic spinal cord compression differ and are reflected in the difference in clinical signs and response to treatment seen in these two types of intervertebral disk disease.

Question 466

Which characteristica of acute spinal cord injury are associated with acute type I disk extrusion?

Answer 466

Hemorrhage, edema, and necrosis of spinal cord gray and white matter are characteristic of acute spinal cord injury associated with acute type I disk extrusion. Type I disk extrusions often are associated with rupture of vertebral venous sinuses, and hemorrhage into the epidural space may increase the degree of spinal cord compression. The nucleus pulposus may also penetrate the dura mater. Traumatic rupture of the anulus fibrosus and extrusion of normal nucleus pulposus may occur, resulting in spinal cord compression and acute onset of clinical signs indicative of a transverse myelopathy

Question 467

Why do dogs affected by disk extrusion commonly show clinical signs that may progress slowly over several days or may manifest periods of improvement and subsequent worsening over weeks or months.

Answer 467

These findings are probably associated with extrusion of small amounts of disk material into the spinal canal over a period of time.

Question 468

Clinical signs associated with type I disk extrusion in the cervical spine usually are less severe than those associated with extrusions in the thoracolumbar region. Why?

Answer 468

Because the vertebral canal in this region is larger in diameter in relation to the spinal cord than is the case in the thoracolumbar region.

Question 469

Ipsilateral Horner's syndrome and hyperthermia have been described in cases of acute, severe, dorsolateral cervical disk extrusions. LMN deficits in the thoracic limbs may be seen in caudal cervical disk extrusions. Thoracic limb lameness may also be seen in caudal cervical disk extrusions as a result of nerve root compression, particularly from lateral disk extrusions in which disk material enters an intervertebral foramen. Clinical findings with thoracolumbar type I disk extrusion, which depend on the severity of spinal cord injury. Neurologic deficits usually are indicative of a ................. between T....and L...... because most disk extrusions in this region occur between T.... and L....... LMN signs may be seen in the pelvic limbs if disk extrusion occurs caudal to L..... as a result of compression of the lumbosacral spinal cord or the nerves of the cauda equina. LMN signs also may be seen in paraplegic animals with progressive hemorrhagic myelomalacia.

Answer 469

Clinical findings with thoracolumbar type I disk extrusion, which depend on the severity of spinal cord injury. Neurologic deficits usually are indicative of a transverse myelopathy between T3 and L3 because most disk extrusions in this region occur between T11 and L3. LMN signs may be seen in the pelvic limbs if disk extrusion occurs caudal to L3 as a result of compression of the lumbosacral spinal cord or the nerves of the cauda equina. LMN signs also may be seen in paraplegic animals with progressive hemorrhagic myelomalacia.

Question 470

thoracolumbar type I disk extrusion: The panniculus reflex may be depressed or absent caudal to the site of disk extrusion. The site of a lesion is usually ........ or........ vertebral spaces ............ to the loss or depression of the panniculus reflex. The Schiff-Sherrington sign may be seen in animals with acute type I disk extrusion ................... to ...........

Answer 470

The panniculus reflex may be depressed or absent caudal to the site of disk extrusion. The site of a lesion is usually one or two vertebral spaces cranial to the loss or depression of the panniculus reflex. The Schiff-Sherrington sign may be seen in animals with acute type I disk extrusion caudal to T2.

Question 471

Type II disk protrusion: Neurologic deficits usually are indicative of?

Answer 471

Neurologic deficits usually are indicative of a cervical or thoracolumbar myelopathy.

Question 472

Type II disk protrusion:: the most common clinical finding?

Answer 472

Paraparesis or tetraparesis, depending on the site of the lesion, is the most common clinical finding, and deficits may be asymmetric. Apparent neck or back pain may or may not be a feature of type II disk protrusion.

Question 473

Ischemic myelopathy results from ?

Answer 473

Ischemic necrosis of spinal cord gray and white matter associated with fibrocartilaginous emboli that occlude arteries and/or veins of the leptomeninges and spinal cord parenchyma of dogs or cats. This disease is characterized by an acute onset of neurologic deficits and is generally nonprogressive after several hours. In most cases the substance occluding the spinal cord arteries and veins has histologic and histochemical properties similar to those of fibrocartilage of intervertebral disks and is presumed to originate from the nucleus pulposus of an intervertebral disk. Most affected animals do not have evidence of degenerative intervertebral disk disease and are dog breeds that have a low incidence of degenerative disk disease and type I disk extrusion. Ischemic myelopathy should be suspected in any dog (especially large- and giant-breed dogs) with an acute onset of nonprogressive neurologic deficits that are not associated with apparent spinal pain,

Question 474

The term lumbosacral vertebral canal stenosis encompasses a spectrum of disorders that result in? Acquired?

Answer 474

Results in narrowing of the lumbosacral vertebral canal, with consequent compression of the cauda equina. The term cauda equina syndrome describes a group of neurologic signs that result from compression, destruction, or displacement of the nerve roots and spinal nerves that form the cauda equina and that have a variety of causes, including lumbosacral vertebral canal stenosis. Lumbosacral vertebral canal stenosis is defined as an acquired disorder of large-breed dogs that results from several or all of the following: type II disk protrusion (dorsal bulging of the anulus fibrosus), hypertrophy and/or hyperplasia of the interarcuate ligament, thickening of the vertebral arches or articular facets, and, infrequently, subluxation/instability of the lumbosacral junction. It is likely that several separate disorders currently are included in this definition.

Question 475

The mucopolysaccharidoses are a group of genetic diseases that result from defects in the metabolism of .....................Two subclasses have been recognized in cats, and paraparesis associated with spinal cord compression has been reported in .............. with mucopolysaccharidosis VI (MPS VI).[6] MPS I, which is due to a deficiency of alphal-iduronidase, has been reported in a ...................

Answer 475

The mucopolysaccharidoses are a group of genetic diseases that result from defects in the metabolism of glycosaminoglycans. Two subclasses have been recognized in cats, and paraparesis associated with spinal cord compression has been reported in Siamese cats with mucopolysaccharidosis VI (MPS VI). MPS VI is the result of a deficiency of the lysosomal enzyme arylsulfatase B; in addition to causing characteristic physical deformities, it can result in (1) skeletal changes, and (2) bony proliferation in the intervertebral foramina, causing nerve root compression. MPS I, which is due to a deficiency of alphal-iduronidase, has been reported in a domestic shorthair cat

Question 476

The term myelodysplasia describes a number of malformations of the ...............believed to result from incomplete closure or development of the ..........tube.

Answer 476

The term myelodysplasia describes a number of malformations of the spinal cord believed to result from incomplete closure or development of the neural tube. Clinical signs vary in severity and usually are referable to a transverse myelopathy between T3 and L3. Clinical abnormalities usually are evident at 4 to 6 weeks of age, when puppies become ambulatory.

Question 477

What is a pilonidal sinus?

Answer 477

A pilonidal sinus is an invagination of the skin dorsal to the spine that extends below the skin to variable depths and in some cases as far as the dura mater, where it may communicate with the subarachnoid space. Purebred and crossbred Rhodesian Ridgeback dogs are most commonly affected, although other dog breeds may be affected. If the sinuses communicate with the subarachnoid space, extension of infection results in meningitis or myelitis.

Question 478

What is an epidermoid cyst?

Answer 478

Epidermoid cysts have been reported to occur in the brain and spinal cord of dogs.[191] Such cysts are thought to arise from entrapment and subsequent growth of primordial epithelial cells during closure of the neural tube. Signs resulting from a spinal dermoid or epidermoid cyst depend on its location. . Signs resulting from a spinal dermoid or epidermoid cyst depend on its location.

Question 479

What is a skeletal osteochondroma? Clinical findings?

Answer 479

A cartilage-capped exostosis arising from the surface of a bone formed by endochondral ossification. Osteochondromatosis may occur anywhere in the vertebral column but most commonly is found in the thoracic and lumbar spine. The disease may result in spinal cord compression and clinical signs indicative of a progressive transverse myelopathy between T3 and L3. Neurologic deficits are often asymmetric

Question 480

What is progressive hemorrhagic myelomalacia (PHM)?

Answer 480

Acute, severe spinal cord injury may result in progressive ascending and descending infarction and hemorrhagic necrosis of the spinal cord parenchyma. Occurs infrequently and usually follows peracute explosive extrusion of a thoracolumbar disk, but it may also be seen after other types of spinal cord trauma. In animals with PHM, hemorrhagic necrosis of a large number of spinal cord segments may occur over a period of hours to days.

Question 481

Toxoplasma gondii is an obligate, intracellular, coccidian parasite. Cats are the only known definitive host of the organism and as such pass environmentally resistant oocysts in feces. T. gondii infection may cause a.......... or ......................in dogs or cats. Animals are infected after ingesting meat containing Toxoplasma ................and/or ...............; after ingesting cat feces containing ..................oocysts; or by transplacental or congenital infection. The infective organism is spread hematogenously to most organs of the body, including the CNS. Clinical signs?

Answer 481

T. gondii infection may cause a focal or disseminated myelopathy in dogs or cats. Animals are infected after ingesting meat containing Toxoplasma bradyzoites and/or tachyzoites; after ingesting cat feces containing sporulated oocysts; or by transplacental or congenital infection. The infective organism is spread hematogenously to most organs of the body, including the CNS. Although the incidence of disease associated with T. gondii is low, opportunistic infection in immunosuppressed animals may be more widespread than previously reported. Immaturity and concurrent CD virus infection may result in an increased susceptibility of dogs to toxoplasmosis. In dogs with systemic toxoplasmosis, the incidence of CNS involvement is high. In cats, concurrent infection with FeLV or FIV or administration of corticosteroids may predispose the animal to the development of clinical signs of toxoplasmosis through immunosuppression and reactivation of latent infection. Animals with CNS involvement by T. gondii usually have clinical signs of progressive multifocal or disseminated disease. Clinical signs indicating a focal transverse or diffuse myelopathy may be seen initially. Neurologic deficits depend on the site of involvement and may be either UMN or LMN deficits. If LMNs are involved, denervation may result in severe muscle atrophy.

Question 482

Neospora caninum is a recently discovered, cyst-forming coccidium. This protozoal parasite is associated most commonly with natural infection in dogs and cattle. The organism forms meronts in many tissues of dogs, especially the .................and ..............., resulting in meningoencephalomyelitis. Clinical signs?

Answer 482

The organism forms meronts in many tissues of dogs, especially the brain and spinal cord, resulting in meningoencephalomyelitis. Clinically, this protozoal disease appears similar to toxoplasmosis; however, CNS signs (progressive ascending paralysis) and myositis are seen more commonly than in toxoplasmosis, and T. gondii almost always has been associated with concurrent disease in dogs (e.g., CD infection), whereas N. caninum appears to be a primary pathogen. Neosporosis may cause fatal disease in dogs of all ages (several weeks to 15 years). Puppies are affected more severely than older dogs. These dogs are infected transplacentally from the dam Young dogs develop an ascending paralysis, with the pelvic limbs affected more severely than the thoracic limbs. Other signs of dysfunction include difficulty swallowing, paralysis of the jaw, muscle flaccidity, and muscle atrophy. Ingestion of raw meat appears to be a risk factor for both T. gondii and N. caninum infection

Question 483

What is spina bifid a?

Answer 483

Spina bifida describes a group of developmental defects characterized by failure of fusion of the vertebral arches with or without protrusion or dysplasia of the spinal cord and meninges. Spina bifida is the absence of a portion of the dorsal elements of the vertebrae. The spinal cord and meninges may be normal (spina bifida occulta), or they may be abnormal, and the meninges and/or spinal cord may protrude through the vertebral defect. Occurs in both dogs and cats

Question 484

What are intraarachnoid cysts?

Answer 484

Intraarachnoid membrane accumulations of CSF that may occur in any location along the cerebrospinal axis of cats or dogs.

Question 485

The term spinal stenosis indicates?

Answer 485

A narrowing of the vertebral canal. ). Spinal stenosis may result either from bony impingement on neural elements or from compression of neural tissue by nonosseous components of the walls of the vertebral canal

Question 486

Spondylosis deformans is characterized by?

Answer 486

Formation of osteophytes (bony spurs) around the margins of vertebral endplates. Osteophytes may form at one or more intervertebral disk spaces and may appear to bridge or almost bridge intervertebral disk spaces. Radiographic appearance of solid bony bridges. The incidence and size of vertebral osteophytes increase with age. The caudal thoracic, lumbar, and lumbosacral spinal segments are affected most frequently. Because these segments are the areas of greatest spinal mobility, dynamic and mechanical factors may play a role in osteophyte formation.

Question 487

Spinal synovial cysts may arise from?

Answer 487

The articular facets and surrounding connective tissues of the cervical and thoracolumbar vertebrae of dogs. These cysts may result in progressive extradural compression of the spinal cord.

Question 488

Syringomyelia and hydromyelia result in similar signs of spinal cord dysfunction. What is syringomyelia?

Answer 488

Syringomyelia is a cavitation of the spinal cord that may occur secondary to hydromyelia (communicating syringomyelia) or may not communicate with the central canal (noncommunicating syringomyelia). Syringomyelia may be associated with spinal cord tumors, myelitis, meningitis, and spinal cord trauma. The cause of syringomyelia is not known, but the condition may result from venous obstruction or distention or may be due to mechanical disruption or shearing of spinal cord tissue planes. Regardless of the cause, cavitation may be progressive, probably along planes of structural weakness, such as the gray matter of the dorsal horns, and subsequent necrosis and edema of the spinal cord parenchyma around such a cavitation (or dilated central canal) can result in the onset and progression of clinical signs.

Question 489

What is hydromyelia?

Answer 489

Hydromyelia is a dilatation of the central canal with or without syringomyelia that may be idiopathic or it may be associated with congenital malformations, or lesions resulting in obstruction of CSF flow into the spinal subarachnoid space at the foramen magnum. Hydromyelia and syringomyelia in these animals probably results from intracranial and spinal cord venous or arterial pressure changes and associated CSF pressure changes.

Question 490

Arteriovenous malformations and vascular tumors may occur anywhere in the ....................., and clinical signs usually reflect a progressive................

Answer 490

Arteriovenous malformations and vascular tumors may occur anywhere in the spinal canal, and clinical signs usually reflect a progressive transverse myelopathy. An acute onset or sudden worsening of clinical signs may occur as a result of hemorrhage or thrombosis associated with abnormal vasculature of the malformation or tumor. Clinical signs may be the result of spinal cord compression or ischemia.

Question 491

The peripheral nervous system (PNS) includes?

Answer 491

All nerve structures outside of the central nervous system (CNS, i.e., the brain and spinal cord).

Question 492

The PNS is composed of ?

Answer 492

1. Motor nerve fibers innervating skeletal muscle 2. Sensory nerve fibers carrying touch, pain and proprioceptive position information from the skin, joints and muscles 3. Afferent fibers carrying special sense information (e.g., auditory and vestibular systems) 4. Autonomic fibers innervating the thoracic and abdominal viscera, as well as other structures (e.g., salivary glands, pupil, baroreceptors). The autonomic system is further divided into the sympathetic and parasympathetic systems.

Question 493

Peripheral nerve fibers may arise from?

Answer 493

1. The ventral horn of the spinal cord, exiting via the ventral root (motor and sympathetic fibers) 2. The dorsal root ganglion adjacent to the spinal cord, entering the cord via the dorsal root (sensory fibers) 3. The brainstem or adjacent ganglia (motor and parasympathetic fibers) entering or exiting in cranial nerves. Although some nerves carry purely motor or sensory information, most nerves are composed of a combination of motor and sensory fibers. Thus, both sensory and motor functions are often compromised in peripheral nerve disorders.

Question 494

Which fibers exit via the ventral root?

Answer 494

Motor and sympathetic

Question 495

Which fibers exit via the dorsal root?

Answer 495

sensory fibers fibers

Question 496

Which fibers exit via the brainstem or adjacent ganglia?

Answer 496

Motor and parasympathetic fibers

Question 497

What is the motor unit?

Answer 497

The functional component responsible for skeletal muscle activity and consists of a motor neuron, its axon, the neuromuscular junction, and the muscle fibers innervated by that neuron.

Question 498

Disease of the motor unit is known as?

Answer 498

Neuromuscular disease or lower motor neuron disease.

Question 499

A neuropathy refers to?

Answer 499

Disease of the peripheral nerves (either spinal or cranial nerves). A polyneuropathy affects multiple peripheral nerves, often in a diffuse manner.

Question 500

A radiculopathy refers to?

Answer 500

Disease of the nerve roots.

Question 501

The majority of peripheral nerve disorders in veterinary medicine have a clinical presentation dominated by?

Answer 501

Dysfunction of the motor nerves, although sensory and autonomic signs are seen with some conditions.

Question 502

Characteristic clinical signs of peripheral nerve disorders include?

Answer 502

Paresis, hypotonia, muscle atrophy, and reduced or absent segmental spinal reflexes. The paresis may involve all four limbs or may manifest as paraparesis and often results in a short-strided or stilted gait. Dysphonia, dysphagia, inspiratory stridor, megaesophagus, and reduced or absent gag and palpebral reflexes may be seen due to involvement of the recurrent laryngeal, glossopharyngeal, vagus, and facial nerves

Question 503

Neuromuscular junction and muscle disorders can result in many of the same signs and can be difficult to distinguish from motor nerve disease based on clinical examination alone. Signs of sensory dysfunction include ........?

Answer 503

Ataxia, loss of proprioceptive positioning, reduced or absent spinal reflexes, and paresthesia or anesthesia, potentially resulting in self-mutilation.

Question 504

Autonomic dysfunction may result in......?

Answer 504

Vomiting or regurgitation, diarrhea, ileus, urinary retention, incontinence, impaired lacrimation and salivation, and pupillary dysfunction.

Question 505

Diabetic neuropathy is one of the most common causes of peripheral nerve dysfunction in human patients and results in significant morbidity. Does it occur in small animals?

Answer 505

Yes, rarely seen in cats.

Question 506

Signs of neuromuscular dysfunction have been frequently associated with hypothyroidism in both canine and human patients. The underlying pathophysiology of this association remains poorly characterized but involves both peripheral nerve and muscle. Thyroid hormone deficiency appears to lead to both ........ damage and .......... Accumulation of glycosaminoglycans and glycogen within .........cells may be responsible for cellular dysfunction and resultant demyelinating change. Altered sodium-potassium ATPase activity, with impaired axonal transport, is another potential mechanism.

Answer 506

Signs of neuromuscular dysfunction have been frequently associated with hypothyroidism in both canine and human patients. The underlying pathophysiology of this association remains poorly characterized but involves both peripheral nerve and muscle. Thyroid hormone deficiency appears to lead to both axonal damage and demyelination. Accumulation of glycosaminoglycans and glycogen within Schwann cells may be responsible for cellular dysfunction and resultant demyelinating change. Altered sodium-potassium ATPase activity, with impaired axonal transport, is another potential mechanism. Mulitple difference scenarios of neuromuscular diseases possible associated with hypothyroidism.

Question 507

Peripheral nerve dysfunction due to neoplasia may result from?

Answer 507

Compression of nerve tissue due to a nerve or nerve sheath tumor or adjacent neoplastic tissue. It may also occur as a paraneoplastic process. (Trigeminal nerve sheath tumors are the most common cranial nerve neoplasms and typically lead to unilateral masticatory muscle atrophy)

Question 508

Acute polyradiculoneuritis is a relatively common disorder, is seen in both dogs and cats, and causes an acute, ascending, flaccid tetraparesis or tetraplegia. Severe cases progress to involve the cranial nerves and respiratory musculature, leading to hypoventilation. The evidence strongly suggests that this is an................disease.

Answer 508

immune-mediated disease.

Question 509

Chronic Inflammatory Demyelinating Polyneuropathy. Clinical signs develop insidiously and are slowly progressive, typically involving the pelvic limbs first and then the thoracic limbs. Underlying etiology?

Answer 509

The underlying etiology is unknown but is suspected to be immune-mediated

Question 510

What is sensory Polyganglioradiculoneuritis?

Answer 510

An inflammatory neuropathy preferentially affecting the sensory nerves, nerve roots, and dorsal root ganglia. The underlying cause of the condition is unknown. Clinical signs consist of ataxia, reduced to absent proprioception and segmental spinal reflexes (particularly the patellar reflex), and hypalgesia of the face, trunk, or limbs.[140] Dysphagia, regurgitation, megaesophagus, anisocoria, and self-mutilation have been reported in some cases

Question 511

Trauma to peripheral nerves can occur secondary to a variety of insults: Terminologies describe the degree of nerve injury based on disruption of the myelin sheath, axon, and supporting tissue: ............refers to the failure of nerve conduction without structural changes, secondary to blunt trauma, compression, or ischemia. ............ refers to an injury characterized by disruption of the axon and myelin sheath, but with preservation of surrounding connective tissue elements. ................ refers to partial or complete severing of a nerve, including the axon, myelin sheath, and connective tissue elements and carries a worse prognosis for recovery.

Answer 511

Neurapraxia refers to the failure of nerve conduction without structural changes, secondary to blunt trauma, compression, or ischemia. Axonotmesis refers to an injury characterized by disruption of the axon and myelin sheath, but with preservation of surrounding connective tissue elements. Neurotmesis refers to partial or complete severing of a nerve, including the axon, myelin sheath, and connective tissue elements and carries a worse prognosis for recovery.

Question 512

The brachial plexus is composed of nerve roots originating from the sixth cervical to the second thoracic segments of the spinal cord and innervates the thoracic limb. Brachial plexus injury results in? (clinical signs)

Answer 512

A non–weight-bearing lameness or paresis of the limb, which is often carried in a flexed position, variable lack of spinal reflexes and sensation to the limb, and in some cases ipsilateral Horner's syndrome or loss of the cutaneous trunci reflex

Question 513

A variety of toxins, pharmaceuticals, and other agents have been reported to cause peripheral neuropathies in small animals: such as?

Answer 513

Such substances include heavy metals (e.g., mercury, thallium, lead), antibiotics (e.g., lasalocid, nitrofurantoin, salinomycin), pesticides (e.g., organophosphates), organic solvents and chemicals (e.g., acrylamide, hexacarbons), vitamins (e.g., pyridoxine), and antineoplastic drugs (e.g., vincristine, vinblastine, cisplatin)

Question 514

AUTONOMIC DISORDERS: Dysautonomia refers to?

Answer 514

Generalized dysfunction of the autonomic nervous system. The cause of this syndrome is unknown, although the epidemiologic characteristics of the disease suggest an infectious or toxic etiology. Clinical signs include gastrointestinal dysfunction (vomiting, regurgitation, diarrhea, weight loss, tenesmus, constipation, inappetence, dysphagia); urinary bladder dysfunction (dysuria, distended bladder); ocular signs (mydriasis, absent pupillary light reflexes, decreased tear production, protruding nictitans, photophobia); nasal discharge; sneezing; dry mucous membranes; and decreased or absent anal tone. Autonomic dysfunction as part of a more generalized peripheral neuropathy has been well documented in human patients with a variety of conditions, including diabetes mellitus, paraneoplastic polyneuropathy, GBS, and toxic neuropathies

Question 515

Disorders of Skeletal Muscles: Overview: Myopathic animals generally develop generalized weakness, exercise intolerance, and a stiff, stilted, “bunny hopping” gait. These signs are most pronounced in the ...................limbs initially but may generalize, depending on the condition. Are the myotactic reflexes, propriceptive responsen and normal mentation and sensation normally preserved? Frequent findings?

Answer 515

pelvic limbs Myotactic reflexes, particularly the patellar reflex, are preserved except in select myopathies. Proprioceptive placing and hopping responses remain normal if the animal is supported adequately during testing. Normal mentation and sensation are preserved. Atrophy, focal or generalized, is a frequent finding, as is myalgia. Sialorrhea, a voice change, dyspnea, dysphagia, or megaesophagus may develop with involvement of the muscles of the tongue, larynx, pharynx, or esophagus.

Question 516

Polymyosits: Ethologies and clinical signs?

Answer 516

Immune-mediated polymyositis, caused by an autoimmune response against skeletal muscles, is reported in dogs and cats. Its inciting cause is frequently unknown. Polymyositis may be part of a paraneoplastic syndrome in Boxers. Various infectious agents can also affect skeletal muscles (infectious Polymyositis) Clinical signs include progressive weakness, generalized atrophy (muscle swelling may be seen initially), myalgia, a shifting leg lameness, and hyporeflexia. A voice change, fever, exophthalmos, decreased ability to open the jaw, and cardiac involvement may be found. Megaesophagus and dysphagia are particularly common in Newfoundlands. Acute-onset cervical ventroflexion, weakness, and an inability to jump predominate in cats. Unclassified necrotizing myositis and granulomatous myositis are also described in dogs.

Question 517

NONINFLAMMATORY MYOPATHIES :Myotonia Congenita is caused by? Manifests as?

Answer 517

Myotonia congenita is caused by a sarcolemmal chloride channel dysfunction that results in abnormal myofiber excitability. The disorder manifests as persistent muscle contraction despite termination of voluntary effort or of mechanical/electrical stimulation. Clinical signs develop by 6 months of age and include marked hypertonicity and hypertrophy, particularly of the proximal limb, neck, and tongue muscles.

Question 518

Muscular dystrophy is caused by?

Answer 518

A protein abnormality most commonly in the dystrophin glycoprotein complex linking the myofiber cytoskeleton to the extracellular matrix.

Question 519

Ischemic (neuro)myopathy is most commonly the result of ?

Answer 519

Aortic thromboembolism in cats with cardiac disease but is also reported in dogs secondary to systemic disease

Question 520

METABOLIC MYOPATHIES: Primary Metabolic Myopathies: such as?

Answer 520

Mitochondrial myopathies have been identified in Clumber and Sussex Spaniels homozygous for a pyruvate dehydrogenase phosphatase 1 (PDP1) mutation.[67] Lipid storage myopathies are reported in dogs presenting with myalgia, weakness, generalized atrophy, lameness, and tremors. Glycogen storage disorders caused by inherited errors in glycogen metabolism are reported in dogs and cats. Clinical signs generally manifest within the first year of life. Malignant hyperthermia is an inherited disorder in dogs and cats characterized by sustained muscle contraction and hyperthermia triggered by inhalant anesthetics, depolarizing neuromuscular drugs (i.e., succinylcholine) or, less frequently, stress or exercise.[74] Affected dogs may have previously been anesthetized without complications.

Question 521

Secondary Metabolic Myopathies: such as?

Answer 521

Hyperadrenocorticism and iatrogenic glucocorticoids can alter muscle metabolism in dogs and, rarely, cats.[75] Muscle wasting and weakness are most frequent, although pseudomyotonic signs can develop in a subset of dogs. Hypoadrenocorticism can cause generalized weakness, muscle cramping, and pharyngeal or esophageal dysfunction. Hypothyroid myopathy (and neuropathy) can develop in dogs. Hyperthyroid myopathy is reported in cats. Affected cats are weak and have muscle tremors and neck ventroflexion Hypokalemia caused by illness or diet or inherited as episodic hypokalemia in Burmese kittens can cause generalized weakness, neck ventriflexion, and exercise intolerance Hyperkalemic periodic paralysis is reported in an American Pit Bull Terrier with episodic weakness, collapse, and tongue protrusion

Question 522

The neuromuscular junction (NMJ) is a specialized synapse connecting ...........nerves to the final effectors of movement, the ................. fibers. A peripheral motor nerve and its branches, along with corresponding NMJ and innervated muscle fibers, are known as a motor unit.

Answer 522

The neuromuscular junction (NMJ) is a specialized synapse connecting peripheral motor nerves to the final effectors of movement, the skeletal muscle fibers. A peripheral motor nerve and its branches, along with corresponding NMJ and innervated muscle fibers, are known as a motor unit.

Question 523

The NMJ transmits the information from action potentials traveling down the nerve to the muscle fibers through the release of a neurotransmitter, specifically .................... An action potential leads to depolarization of the cell membrane at the nerve terminal, which leads to an influx of ............. ions through voltage-gated ............. channels. The ..................s packaged in............... concentrated at the nerve terminal, each of which contains a specific amount (“quanta”) of .............. ...............facilitates fusion of the vesicles to the cell membrane and the release of ..............into the NMJ.

Answer 523

The NMJ transmits the information from action potentials traveling down the nerve to the muscle fibers through the release of a neurotransmitter, specifically acetylcholine (ACh). An action potential leads to depolarization of the cell membrane at the nerve terminal, which leads to an influx of calcium ions through voltage-gated calcium channels. The ACh is packaged in vesicles concentrated at the nerve terminal, each of which contains a specific amount (“quanta”) of ACh. Calcium facilitates fusion of the vesicles to the cell membrane and the release of ACh into the NMJ. ACh molecules diffuse across the synapse, binding to receptors (AChR) on the surface of the muscle fibers (endplate), which leads to sodium ion influx and a corresponding endplate potential. If strong enough, this endplate potential leads to muscle membrane depolarization and subsequent release of calcium ions from the sarcoplasmic reticulum, with ensuing contraction of the muscle fibers.

Question 524

Free ACh within the NMJ is broken down by the enzyme .......................In normal motor units.

Answer 524

Free ACh within the NMJ is broken down by the enzyme acetylcholinesterase (AChE). In normal motor units, there is an overabundance of ACh and AChR, and the endplate potentials produced by nerve depolarization greatly exceed what is required for muscle fiber contraction. This excess is known as the safety factor for neuromuscular transmission.

Question 525

Interference with the release of ACh from the nerve terminal or with binding of ACh to the muscle membrane leads to impaired neuromuscular transmission. This typically manifests as weakness with several possible clinical presentations, such as?

Answer 525

The first is acute, flaccid tetraparesis or tetraplegia, which is seen with tick paralysis, botulism, elapid snake envenomation, and the fulminant form of myasthenia gravis. Paresis is usually accompanied by hypotonia, reduced or absent segmental spinal reflexes, and after several days, muscle atrophy. Cranial nerve signs—such as dysphonia, dysphagia, inspiratory stridor, megaesophagus, and reduced or absent gag and palpebral reflexes—are seen with some disorders. The cutaneous trunci reflex may also be absent. Interestingly, voluntary tail movement and anal tone are often preserved despite the absence of voluntary movement elsewhere in the body. The second clinical presentation is episodic weakness exacerbated by activity or exercise. Myasthenia gravis is the most common disease process that gives rise to this observation, although polyneuropathies, myopathies, metabolic disease, and cardiovascular dysfunction must also be considered. The third clinical presentation is paraparesis, or tetraparesis, that is relatively constant and often results in a short-strided or stilted gait. The differential diagnosis is similar to that for episodic weakness. Finally, an excess of ACh within the NMJ, typically due to interference with AChE activity by a toxin, leads to overstimulation of muscle fibers; involuntary muscle activity, such as spasms and tremors; paresis characterized by a stiff, choppy gait; and accompanying parasympathetic signs.

Question 526

What is botulism caused by?

Answer 526

By seven antigenically distinct exotoxins released by the gram-positive, saprophytic, anaerobic bacteria Clostridium botulinum. There is varying species susceptibility to these toxins. The majority of reports on dogs have implicated type C toxin. Domestic cats appear to be relatively resistant to intoxication. The disease is usually contracted through ingestion of intact toxin present within carrion or contaminated food, although bacterial colonization of body tissues with subsequent toxin release is possible.

Question 527

How does type C bolulinum toxin cause botulism?

Answer 527

Type C toxin interferes with ACh release from the nerve terminal through the cleavage of proteins essential for the docking and fusion of synaptic vesicles with the presynaptic membrane, particularly syntaxin.

Question 528

Clinical signs of botulism?

Answer 528

Clinical signs are similar to other causes of acute NMJ disease and include ascending, flaccid tetraparesis; hypotonia; reduced or absent segmental spinal reflexes; and hypoventilation. Signs of cranial nerve dysfunction—including facial paresis, mydriasis, decreased jaw tone, dysphonia, dysphagia, megaesophagus, and reduced or absent gag reflexes—are frequently seen. Sensation is preserved. Involvement of autonomic systems can result in mydriasis, keratoconjunctivitis sicca, bradycardia or tachycardia, constipation, and urinary retention. Clinical signs typically occur within 24 to 48 hours of toxin ingestion but may be delayed for up to 6 days.

Question 529

Myasthenia gravis (MG) results from a failure ofP

Answer 529

Myasthenia gravis (MG) results from a failure of neuromuscular transmission at the level of the ACh receptor on the muscle membrane. This is most commonly caused by an acquired, immune-mediated process, but it can also be caused by a congenital paucity of functional receptors.

Question 530

Acquired MG is the result of?

Answer 530

An immune-mediated attack on the AChR. Circulating antibodies against the AChR bind to the receptor, leading to direct interference with neuromuscular transmission, binding and activation of complement, accelerated degradation of AChR, and remodeling and destruction of the postsynaptic muscle membrane. Some animals have antibodies against non-AChR muscle proteins, such as titin, and the ryanodine receptor

Question 531

Clinical signs of generalized MG?

Answer 531

Animals with generalized MG have episodic weakness affecting all four limbs that worsens with activity and then improves after a period of rest. Affected animals develop a progressively shorter, stilted stride, followed by sitting or lying down and a reluctance or inability to walk. The pelvic limbs often appear to be more severely affected than the thoracic limbs. Cervical ventroflexion may also be present. There is no ataxia, and proprioceptive testing, postural reactions, segmental spinal reflexes, and muscle mass and tone are usually normal. both dogs and cats frequently have involvement of the facial, pharyngeal, laryngeal, and esophageal musculature, leading to facial weakness, dysphonia, dysphagia, salivation, regurgitation, and aspiration pneumonia

Question 532

Effect of administration of the short-acting anticholinesterase drug edrophonium?

Answer 532

Can be used diagnostically to assess improvements in muscle strength, gait, or the ability to swallow. This drug inhibits AChE, allowing more ACh to remain in the NMJ, thereby improving neuromuscular transmission.

Question 533

Therapy for animals with MG?

Answer 533

Includes increasing the amount of ACh in the NMJ to counteract the deficiency of AChR and immunosuppression. The first of these is accomplished with the administration of long-acting anti-AChE drugs. Pyridostigmine bromide is the medication of choice, although neostigmine can also be used. Although many animals can be successfully managed with anti-AChE drugs alone, acquired MG is an immune-mediated disease, and a clear rationale exists for immunomodulatory therapy. While glucocorticoid therapy appears to be beneficial in many cases,[2,103-105] such therapy is controversial in animals for a number of reasons. First, a large proportion of dogs with MG have involvement of the esophagus and are prone to aspiration pneumonia. As a result, immunosuppressive corticosteroid administration must be undertaken with care and is avoided by many clinicians for fear of worsening the pneumonia. Third, spontaneous remission of MG has been reported to occur in approximately 89% of affected dogsSecond, the polydipsia associated with glucocorticoid therapy may increase the risk of regurgitation. Other immunosuppressive medications used in dogs are azathioprine, cyclosporine A and mycophenolate mofetil. In theory, these drugs may have the advantage of targeting the adaptive immune system, and T cells in particular, while sparing innate immunity and neutrophil function, which may be beneficial in animals with pneumonia. These medications also circumvent many of the other side effects associated with glucocorticoids, such as polyuria, polydipsia, and polyphagia. Surgical removal of neoplastic tissue is typically recommended in animals with thymoma and can lead to resolution of clinical signs in some.

Question 534

Congenital Myasthenic Syndromes

Answer 534

Presumed congenital MG, or myasthenic syndromes,

Question 535

MISCELLANEOUS TOXINS AND DRUGS: Organophosphates and carbamates both bind to AChE and inhibit its activity. This results in?

Answer 535

Excess ACh within the NMJ, resulting in tremors, muscle fasciculation and spasm, paresis, and a stiff, rigid gait. Excess ACh at parasympathetic and central synapses results in salivation, lacrimation, miosis, diarrhea, bradycardia, bronchoconstriction, and seizures. Diagnosis is based on history, clinical signs, and serum cholinesterase levels. Therapy consists of standard decontamination measures for topical or ingested toxins, supportive care, atropine to counteract parasympathetic effects, and pralidoxime chloride (2-PAM, for organophosphate toxicosis only).[141-143]

Question 536

A variety of drugs have been documented to cause or aggravate neuromuscular blockade, including?

Answer 536

Aminoglycoside antibiotics, tetracyclines, ampicillin, imipenum, ciprofloxacin, magnesium, phenothiazines, methoxyflurane, and various antiarrhythmics. These drugs should be considered as potential causative agents in patients with a consistent anamnesis and should be avoided or used with extreme caution in patients with existing neuromuscular weakness.

Question 537

Från svenskt kompendium

Answer 537

Från svenskt kompendium

Question 538

Mentalt status: Sensoriska impulser inifrån och utanför vår kropp stimulerar ...................... som sedan projiceras på ............... Skador på hjärnstam eller storhjärna kan ge påverkan på mentalt status. • Alert: patienten är pigg och reagerar normalt på stimuli • Letargi/dämpad: patienten är normal men reagerar dämpat på stimuli, detta är vanligt vid många sjukdomstillstånd och är inte specifikt för sjukdomar i hjärnan. • Stupor: patienten sover men ..................... • Koma: patienten sover och kan inte väckas ................... • Förvirrad: patienten reagerar fel och ................på stimuli

Answer 538

Mentalt status: Sensoriska impulser inifrån och utanför vår kropp stimulerar formatio reticularis som sedan projiceras på cortex. Skador på hjärnstam eller storhjärna kan ge påverkan på mentalt status. • Alert: patienten är pigg och reagerar normalt på stimuli • Letargi/dämpad: patienten är normal men reagerar dämpat på stimuli, detta är vanligt vid många sjukdomstillstånd och är inte specifikt för sjukdomar i hjärnan • Stupor: patienten sover men kan väckas av smärtsamt stimuli • Koma: patienten sover och kan inte väckas med smärta • Förvirrad: patienten reagerar fel och olämpligt på stimuli

Question 539

Hållning: Den fysiologiska hållningen upprätthålls av reflexbågar. Receptorer i .............. och ..............., ......... och det .................. systemet skickar information via ................ banor till hjärnan. Sedan förs information tillbaka till musklerna i hals, kropp och extremiteter via motoriska banor. Hållningen kan vara normal eller så kan man se avvikelser som head tilt (huvudlutning- tyder på ett vestibulärt problem, huvudet lutar oftast åt den skadade sidan), ............. (ryggraden devierar lateralt), lordos (svankryggighet), kyfos (kutryggighet), bredbent hållning

Answer 539

Den fysiologiska hållningen upprätthålls av reflexbågar. Receptorer i extremiteter och kropp, synen och det vestibulära systemet skickar information via sensoriska banor till hjärnan. Sedan förs information tillbaka till musklerna i hals, kropp och extremiteter via motoriska banor. Hållningen kan vara normal eller så kan man se avvikelser som head tilt (huvudlutning- tyder på ett vestibulärt problem, huvudet lutar oftast åt den skadade sidan), skolios (ryggraden devierar lateralt), lordos (svankryggighet), kyfos (kutryggighet), bredbent hållning

Question 540

Rörelser: I gången är alla delar av nervsystemet inblandat. Gången regleras av ascenderande (inåtgående) och descenderande (utåtgående) banor samt sk. rörelsecentrum (.............centers). Tänk på att de flesta neurologiska avvikelser blir med uttalade när patienten går ...................

Answer 540

Rörelser: I gången är alla delar av nervsystemet inblandat. Gången regleras av ascenderande (inåtgående) och descenderande (utåtgående) banor samt sk. rörelsecentrum (locomotion centers). Tänk på att de flesta neurologiska avvikelser blir med uttalade när patienten går väldigt långsamt.

Question 541

Det finns 3 typer av ataxi, vilka?

Answer 541

Vestibulär, cerebellär och proprioceptiv

Question 542

Vestibulär ataxi ger även ........ samt ofta nystagmus och ...... Cerebellär ataxi ger även ......... och...............tremor Proprioceptiv ataxi ger även ........... och onormala ................... reaktioner

Answer 542

Vestibulär ataxi ger även head tilt samt ofta nystagmus och strabismus Cerebellär ataxi ger även hypermetri och intentionstremor Proprioceptiv ataxi ger även pares och onormala posturala reaktioner

Question 543

Pares Pares betyder nedsatt ..............., paraplys ............... av motorik.

Answer 543

Pares Pares betyder nedsatt motorik, paralys avsaknad av motorik.

Question 544

Monopares (ett ben), hemipares (båda benen ...............sida), parapares (båda..................), tetrapares (...............)

Answer 544

Monopares (ett ben), hemipares (båda benen på samma sida), parapares (båda bakbenen), tetrapares (alla ben)

Question 545

Pareser delas in i ......................... (.......) och .................... (.........).

Answer 545

Pareser delas in i Upper Motor Neuron (UMN) och Lower Motor Neuron (LMN).

Question 546

LMN systemet består av ..................neuron, ............ nervrot, .........- ............ändplatta och ................

Answer 546

LMN systemet består av α-motorneuron, ventral nervrot, nerv- muskeländplatta och muskel.

Question 547

En skada på LMN ger pares med nedsatta eller inga .............., neurosen muskel............ (märks redan efter ca 10 dagar) och nedsatt muskel.................

Answer 547

En skada på LMN ger pares med nedsatta eller inga reflexer, neurogen muskelatrofi (märks redan efter ca 10 dagar) och nedsatt muskeltonus.

Question 548

UMN systemet består av storhjärnans ............, basala .............., ................ och ..................

Answer 548

UMN systemet består av storhjärnans cortex, basala ganglier, hjärnstam och lillhjärna.

Question 549

En skada på UMN-systemet ger pares, reflexerna är ................. eller ..............., muskel............... utvecklas till följd av att muskeln inte används och muskeltonus är ..............................

Answer 549

En skada på UMN-systemet ger pares, reflexerna är normala eller överdrivna, muskelatrofi utvecklas till följd av att muskeln inte används och muskeltonus är normal eller ökad.

Question 550

Skadans lokalisation: C1-C5 Framben/bakben: UMN/LMN/normal?

Answer 550

Framben: UMN, Bakben: UMN

Question 551

Skadans lokalisation: C6-T2 Framben/bakben: UMN/LMN/normal?

Answer 551

Framben: LMN Bakben: UMN

Question 552

Skadans lokalisation: T3-L3 Framben/bakben: UMN/LMN/normal?

Answer 552

Framben: Normal Bakben: UMN

Question 553

Skadans lokalisation: L4-S3 Framben/bakben: UMN/LMN/normal?

Answer 553

Framben: Normal Bakben: LMN

Question 554

Cirkelgång: Kan ses vid skador i det .............. systemet eller även vid en assymetrisk fokal skada i ....................

Answer 554

Cirkelgång: Kan ses vid skador i det vestibulära systemet eller även vid en assymetrisk fokal skada i storhjärnan.

Question 555

Kranialnerver: Undersökning av kranialnerverna är en viktig del i den neurologiska undersökningen speciellt när sjukdomar i hjärnan misstänks. 12 par kranialnerver ger 24 stycken

Answer 555

Kranialnerver: Undersökning av kranialnerverna är en viktig del i den neurologiska undersökningen speciellt när sjukdomar i hjärnan misstänks. 12 par kranialnerver ger 24 stycken

Question 556

I Olfactorius Kranialnerv ...... är en sensorisk nerv som förmedlar ............

Answer 556

I Olfactorius Kranialnerv I är en sensorisk nerv som förmedlar luktintryck. Luktnerven är svår att undersöka detaljerat. Graden av luktförmåga går inte att fastställa, ej heller går det att skilja om patienten bara känner lukt på vänster eller höger sida. Förmågan att känna dofter kan grovt uppskattas genom att låta patienten lukta sig fram till i vilken han man håller en godis.

Question 557

II Opticus Synnerven. Bildar en del av synbanan samt den ............... delen av .......- och ..............reflexen.

Answer 557

II Opticus Synnerven. Bildar en del av synbanan samt den afferenta delen av hot- och pupillreflexen.

Question 558

Synnervens funktion undersöks med hjälp av?

Answer 558

Dess funktion undersöks med hjälp av hotresponsen (kallas även retinalrespons eller menance), pupillreflexen, bomullstusstesten, oftalmologisk undersökning och ev. hinderbana.

Question 559

Hotrespons: Kranialnerv ....... afferent (sensorisk- ljusledande), kranialnerv ........ efferent (motorisk-gör så att ögat blinkar). När handen förs mot ögat utlöses en blinkning. Håll gärna för det öga som inte undersöks. Undvik att utlösa ett vinddrag som utlöser blinkningen. Viktig test eftersom alla intrakraniella strukturer är inblandad i denna reflex. Ska man bara testa en reflex så testa denna!

Answer 559

Hotrespons: Kranialnerv II afferent (sensorisk- ljusledande), kranialnerv VII efferent (motorisk-gör så att ögat blinkar). När handen förs mot ögat utlöses en blinkning. Håll gärna för det öga som inte undersöks. Undvik att utlösa ett vinddrag som utlöser blinkningen. Viktig test eftersom alla intrakraniella strukturer är inblandad i denna reflex. Ska man bara testa en reflex så testa denna!

Question 560

En onormal hotrespons kan tyda på en perifer skada (..........., ................-synnervskorsningen-, ..................) eller på en central skada (............, ............. eller ....................).

Answer 560

En onormal hotrespons kan tyda på en perifer skada (n. opticus, chiasma-synnervskorsningen-, tractus opticus) eller på en central skada (cerebrum, cerebellum eller hjärnstam).

Question 561

Tänk på att hotresponsen är en inlärd reflex, den saknas normalt på kattungar och valpar yngre än ............. veckor. Hundar med mycket hår framför ögonen kan ha en sämre hotrespons, även de med mycket ............. som normalt inte blinkar fullt.

Answer 561

Tänk på att hotresponsen är en inlärd reflex, den saknas normalt på kattungar och valpar yngre än 10-12 veckor. Hundar med mycket hår framför ögonen kan ha en sämre hotrespons, även de med mycket stora ögon som normalt inte blinkar fullt.

Question 562

Pupillreflex: Kranialnerv ....... afferent, kranialnerv ......... efferent (motorisk-gör så att pupillen ..............).

Answer 562

Pupillreflex: Kranialnerv II afferent, kranialnerv III efferent (motorisk-gör så att pupillen drar ihop sig).

Question 563

Pupilleflexen går endast till .............................. Kan en patient vara blind men ändå ha pupillreflex?

Answer 563

Pupillreflexen går endast till hjärnstammen, patienten kan vara blind men ändå ha pupillreflex.

Question 564

Använd en stark ljuskälla och lys in i ögat, pupillen ska då dra ihop sig (............ reflex). Flytta därefter snabbt ljuskällan till det andra ögat, denna pupill ska då också ha dragit ihop sig (................ reflex).

Answer 564

Använd en stark ljuskälla och lys in i ögat, pupillen ska då dra ihop sig (direkt reflex). Flytta därefter snabbt ljuskällan till det andra ögat, denna pupill ska då också ha dragit ihop sig (indirekt reflex).

Question 565

Bomullstusstest: En bomullstuss släpps från sidan om ansiktet. Ett normalt svar innebär att patienten vrider huvudet mot bomullstussen. Testa vänster och höger öga separat. Detta test är inte helt lätt att tolka, vissa individer bryr sig helt enkelt inte om bomullstussen.

Answer 565

Bomullstusstest: En bomullstuss släpps från sidan om ansiktet. Ett normalt svar innebär att patienten vrider huvudet mot bomullstussen. Testa vänster och höger öga separat. Detta test är inte helt lätt att tolka, vissa individer bryr sig helt enkelt inte om bomullstussen.

Question 566

III Oculomotorius Består av en .......................... del som innerverar 3 av de 7 ögonmusklerna samt en ......................... del som ger pupillkonstriktion.

Answer 566

III Oculomotorius Består av en motorisk del som innerverar 3 av de 7 ögonmusklerna samt en parasympatisk del som ger pupillkonstriktion.

Question 567

För att undersöka den motoriska delen av n. oculomotorius; titta på ögats ....................... (ev. skelning) samt undersök fysiologisk ............................... Den parasympatiska delen kan undersökas genom att titta på ..................... och p................................

Answer 567

För att undersöka den motoriska delen titta på ögats position (ev. skelning) samt undersök fysiologisk nystagmus. Den parasympatiska delen kan undersökas genom att titta på pupillstorlek och pupillreflex.

Question 568

Skador på oculomotorius ger en ventro......... .................. och en oförmåga att föra ögat ..............., ............... och ................ då man undersöker fysiologisk nystagmus.

Answer 568

Skador på oculomotorius ger en ventrolateral strabismus (skelning) och en oförmåga att föra ögat dorsalt, medialt och ventralt då man undersöker fysiologisk nystagmus.

Question 569

Fysiologisk nystagmus: Genom att vrida huvudet åt sidorna och upp och ner utlöses normala ögonrörelser. Den ses alltid i ............... som huvudet roteras och består av en långsam fas i ............ riktning mot hur huvudet roterar samt en snabb fas i ................... som huvudet roterar.

Answer 569

Fysiologisk nystagmus: Genom att vrida huvudet åt sidorna och upp och ner utlöses normala ögonrörelser. Den ses alltid i samma plan som huvudet roteras och består av en långsam fas i den motsatta riktning mot hur huvudet roterar samt en snabb fas i samma riktning som huvudet roterar.

Question 570

Vid skador på det ................... systemet (dubbelsidigt perifert eller centralt) ses ibland ingen fysiologisk nystagmus sk. .....................

Answer 570

Vid skador på det vestibulära systemet (dubbelsidigt perifert eller centralt) ses ibland ingen fysiologisk nystagmus sk. doll ́s eye.

Question 571

n. oculomotorius består av en ..................... del som reglerar pupillens storlek. Pupillens storlek påverkas även av ...................... som inte ingår i någon kranialnerv. Skador på ............................... kan ge ett fullständigt eller partiellt Horner ́s syndrom.

Answer 571

n. oculomotorius består av en parasympatisk del som reglerar pupillens storlek. Pupillens storlek påverkas även av sympaticus som inte ingår i någon kranialnerv. Skador på sympaticusnerven kan ge ett fullständigt eller partiellt Horner ́s syndrom.

Question 572

Horner ́s syndrom karakteriseras av.......(4)

Answer 572

Horner ́s syndrom karakteriseras av mios, ptosis (ögonlocket hänger) enoftalmus och framfall av 3:e ögonlocket.

Question 573

IV ...................... Innerverar en av ........musklerna, ej så viktig. Som för kranialnerv .........gäller att denna nerv undersöks genom att titta på ......................

Answer 573

IV Trocklearis Innerverar en av ögonmusklerna, ej så viktig. Som för kranialnerv III gäller att denna nerv undersöks genom att titta på ögats position.

Question 574

Skador på kranialnerv IV ger en ..................... (på hund krävs fundus undersökning för att kunna se detta). Skador på enbart kranialnerv IV är en mycket ovanlig företeelse.

Answer 574

Dorsolateral strabismus

Question 575

V Trigeminus Trillingnerven är den .............hjärnnerven. Delar sig i ........ delar direkt efter att den lämnat skallen (.............., .............. och ..................).

Answer 575

V Trigeminus Trillingnerven är den grövsta hjärnnerven. Delar sig i 3 delar direkt efter att den lämnat skallen (ophthalmicus, maxillaris och mandibularis).

Question 576

Trigeminus (V) består av en sensorisk del som förmedlar ................... ansiktet samt en motorisk del som innerverar ......................... (de viktigaste är m. .......... och m. ................). Den sensoriska delen undersöks med hjälp av ..............., ................... och genom att testa .................. i ansiktets olika delar. OBS! Undvik på patienter med nacksmärta.

Answer 576

Består av en sensorisk del som förmedlar känsel från ansiktet samt en motorisk del som innerverar tuggmuskulaturen (de viktigaste är m. masseter och m. temporalis). Den sensoriska delen undersöks med hjälp av ögonlocksreflexen, cornalreflexen och genom att testa känseln i ansiktets olika delar. OBS! Undvik på patienter med nacksmärta.

Question 577

Ögonlocksreflexen: Kranialnerv ....... afferent, kranialnerv ............. efferent (motorisk- gör så att ögat blinkar).

Answer 577

Ögonlocksreflexen: Kranialnerv V afferent, kranialnerv VII efferent (motorisk- gör så att ögat blinkar).

Question 578

Vid palpation av ögonlockens inre och yttre del blinkar patienten. Genom att testa både inre och yttre ögonlockskanten har man undersökt 2 av ...............grenar. Vilka?

Answer 578

Vid palpation av ögonlockens inre och yttre del blinkar patienten. Genom att testa både inre och yttre ögonlockskanten har man undersökt 2 av trigeminus grenar (ophthalmicus medialt och maxillaris lateralt).

Question 579

Ögonlocksreflexen: Genom att undersöka känseln i nosen undersöker man den .................. grenen. Genom att nypa eller sticka huden i ansiktet ska man få en uppfattning om patientens förmåga att känna, den .....................grenen förmedlar bla känsel från huden på sidan av nosen samt på kinderna. Nedsatt känsel i ansiktet kan också ge nedsatt ............... och neurotisk .....................

Answer 579

Genom att undersöka känseln i nosen undersöker man den ophthalmiska grenen. Genom att nypa eller sticka huden i ansiktet ska man få en uppfattning om patientens förmåga att känna, den maxillara grenen förmedlar bla känsel från huden på sidan av nosen samt på kinderna. Nedsatt känsel i ansiktet kan också ge nedsatt corneasensibilitet och neuropatisk keratit.

Question 580

Trigeminus motoriska del är mer svårbedömd - känn efter motstånd ......................Palpera .........................Uppmärksamma atrofi av .......................................

Answer 580

Trigeminus motoriska del är mer svårbedömd - känn efter motstånd när munnen öppnas och stängs. Palpera tuggmusklerna. Uppmärksamma atrofi av masseter -och temporalismuskulaturen.

Question 581

Trismus (oförmåga att öppna munnen) förekommer vid inflammation av tuggmuskulaturen – tuggmuskelmyosit- ”masticatory myositis”. .................. skada på..................... ger muskelatrofi av massetermuskeln. ................. skada på ................... ger oförmåga att stänga munnen, ”dropped jaw”.

Answer 581

Trismus (oförmåga att öppna munnen) förekommer vid inflammation av tuggmuskulaturen – tuggmuskelmyosit- ”masticatory myositis”. Enkelsidig skada på trigeminus ger muskelatrofi av massetermuskeln. Dubbelsidig skada på trigeminus ger oförmåga att stänga munnen, ”dropped jaw”.

Question 582

VI Abducens Innerverar m. ...................... och m. ......................... (drar in ögat i ögonhålan). Undersöks med hjälp av ögats ............., fysiologisk ............ samt ...................... Skador på abducens ger en oförmåga ..................... Skador på enbart abducens är som för skador på trochlearis ovanliga.

Answer 582

VI Abducens Innerverar m. retractor lateralis och m. retractor bulbi (drar in ögat i ögonhålan). Undersöks med hjälp av ögats position, fysiologisk nystagmus samt cornealreflexen. Skador på abducens ger en oförmåga att dra in ögat i ögonhålan. Skador på enbart abducens är som för skador på trochlearis ovanliga.

Question 583

Cornealreflexen: Kranialnerv ....... afferent, kranialnerv .......efferent och kranialnerv ...... gör att patienten blinkar. Genom att vidröra cornea så kommer ögat att dras in i ögonhålan och ögat blinkar. Denna reflex kollas vanligen inte i en vanlig neurologisk undersökning.

Answer 583

Cornealreflexen: Kranialnerv V afferent, kranialnerv VI efferent (motorisk del drar in ögat i ögonhålan) och kranialnerv VII gör att patienten blinkar. Genom att vidröra cornea så kommer ögat att dras in i ögonhålan och ögat blinkar. Denna reflex kollas vanligen inte i en vanlig neurologisk undersökning.

Question 584

...................................(3) bedöms med hjälp av fysiologisk nystagmus och ögats position.

Answer 584

III, IV och VI bedöms med hjälp av fysiologisk nystagmus och ögats position.

Question 585

VII Facialis Ansiktsnerven. Består av en ................... del som innerverar ansiktets muskulatur (ej ..................) och ger ansiktet dess mimik. Gör att patienten ............, rör .........., ........... etc. Består också av en sensorisk del som står för ........... från ....... av tungan (..........delen). Den har även en parasympatisk del som innerverar .......................

Answer 585

VII Facialis Ansiktsnerven. Består av en motrisk del som innerverar ansiktets muskulatur (ej tuggmuskler) och ger ansiktet dess mimik. Gör att patienten blinkar, rör öronen, vidgar näsborrar etc. Består också av en sensorisk del som står för smaken från 2/3 av tungan (främre delen). Den har även en parasympatisk del som innerverar tårkörtlar och spottkörtlar.

Question 586

Ansiktsnerven passerar intill .........örat vilket har klinisk betydelse. Den motoriska delen undersöks genom att bedöma ............ samt med hjälp av ............. och ................ (även ............reflexen). Den sensoriska delen kan undersökas genom att ................ Då skador på facialisnerven även kan påverka ...........så bör även..................... test kollas.

Answer 586

Ansiktsnerven passerar intill mellanörat vilket har klinisk betydelse. Den motoriska delen undersöks genom att bedöma ansiktets symmetri samt med hjälp av hotresponsen och ögonlocksreflexen (även cornealreflexen). Den sensoriska delen kan undersökas genom att droppa atropin på tungan (smakar illa). Då skador på facialisnerven även kan påverka tårproduktionen så bör även Schirmer tear test kollas.

Question 587

För att upptäcka en lindrig facialispares så kan det vara till hjälp att lyfta upp nosen genom att sätta ett finger under hakspetsen, jämför läpparna-de ska vara lika långa. Nedsatt funktion gör att ?

Answer 587

För att upptäcka en lindrig facialispares så kan det vara till hjälp att lyfta upp nosen genom att sätta ett finger under hakspetsen, jämför läpparna-de ska vara lika långa. Nedsatt funktion gör att den sjuka sidans läpp och öra hänger och örat rör sig inte, ögat blinkar varken spontant eller efter provokation, nosborren vidgas inte under andning och ibland ses nosen deviera mot den friska sidan. Ibland ses istället en ansiktsspasm.

Question 588

VIII Vestibulococclearis Består av 2 delar. Den vestibulära delen ansvarar för......... Den coccleara delen ansvarar för ............. Det är en relativt kort nerv som går mellan hjärna...... och ...........

Answer 588

VIII Vestibulococclearis Består av 2 delar. Den vestibulära delen ansvarar för balans. Den coccleara delen ansvarar för hörsel. Det är en relativt kort nerv som går mellan hjärnstam och inneröra.

Question 589

Den vestibulära systemet består av speciella ................... i .........örat, den ................ nerven samt ............ som är belägna i hjärna............. Genom olika bansystem påverkar det vestibuära systemet ögonen, bålens och extremiteternas position beroende av huvudets rörelser.

Answer 589

Den vestibulära systemet består av speciella proprioreceptorer i innerörat, den vestibulära nerven samt kärnor som är belägna i hjärnstammen. Genom olika bansystem påverkar det vestibuära systemet ögonen, bålens och extremiteternas position beroende av huvudets rörelser.

Question 590

Hörseln undersöks grovt med att klappa händerna bakom patienten och se om den reagerar. Ofta kan man få god hjälp av anamnesen, upplever ägaren att hunden hör? Hörseln kan undersökas med hjälp av BAER (..................). Genom att titta på hur patienten håller huvud och kropp i vila samt hur den rör sig får man mycket information om hur det ......................... fungerar.

Answer 590

Hörseln undersöks grovt med att klappa händerna bakom patienten och se om den reagerar. Ofta kan man få god hjälp av anamnesen, upplever ägaren att hunden hör? Hörseln kan undersökas med hjälp av BAER (brainstem auditory evoked response). Genom att titta på hur patienten håller huvud och kropp i vila samt hur den rör sig får man mycket information om hur det vestibulära systemet fungerar.

Question 591

Vid problem i den vestibulära delen ses ..............................?

Answer 591

Vid problem i den vestibulära delen ses ataxi (patienten driver eller cirklar åt ett håll), head tilt samt ofta nystagmus och ventral strabismus.

Question 592

Nystagmus, ofrivilliga ögonrörelser, kan vara .....................(3). Horisontell och rotatorisk ses vanligare vid ..................... skada. Den snabba fasen av nystagmusen är åt den............. sidan och den långsamma fasen åt den .................. sidan.

Answer 592

Nystagmus, ofrivilliga ögonrörelser, kan vara horisontell, vertikal eller rotatorisk. Horisontell och rotatorisk ses vanligare vid perifer vestibulär skada. Den snabba fasen av nystagmusen är åt den friska sidan och den långsamma fasen åt den sjuka sidan.

Question 593

IX Glossofaryngeus Förmedlar smak från den bakre ........ delen av tungan. Har inga ”egna” uppgifter, fungerar tillsammans med kranialnerv ............

Answer 593

IX Glossofaryngeus Förmedlar smak från den bakre 1/3 delen av tungan. Har inga ”egna” uppgifter, fungerar tillsammans med kranialnerv X.

Question 594

X Vagus Innerverar ........................ (utom de i ........området). Ansvarar tillsammans med ....... för sensorik och motorik i svalget. Svårt att mäta och undersöka. Finns symtom på sväljningssvårigheter, ändrad röst (skall, jamande), regurgitation, stenosljud från de övre luftvägarna. Undersök med hjälp av ................reflexen. Den ....................... delen av kranialnerv X kan testas genom att lägga fingrarna och trycka lätt mot ögonen, detta ger en .....................................

Answer 594

X Vagus Innerverar bröst- och bukorganen (utom de i bäckenområdet). Ansvarar tillsammans med IX för sensorik och motorik i svalget. Svårt att mäta och undersöka. Finns symtom på sväljningssvårigheter, ändrad röst (skall, jamande), regurgitation, stenosljud från de övre luftvägarna. Undersök med hjälp av sväljningsreflexen, ge patienten mat eller vatten. Den parasympatiska delen av kranialnerv X kan testas genom att lägga fingrarna och trycka lätt mot ögonen, detta ger en reflektorisk bradycardi (oculocardiac reflex).

Question 595

Sväljningsreflexen: Genom att trycka lätt mot svalget kan man stimulera djuret att svälja, om inte det fungerar kan man stoppa ner ett finger i halsen för att på så sätt provocera fram en sväljreflex.

Answer 595

Sväljningsreflexen: Genom att trycka lätt mot svalget kan man stimulera djuret att svälja, om inte det fungerar kan man stoppa ner ett finger i halsen för att på så sätt provocera fram en sväljreflex.

Question 596

XI Accesorius Ingår .............. reflexer. Innerverar m. .......................................... Palpera nacken för att upptäcka muskel.........

Answer 596

XI Accesorius Ingår inte i några reflexer. Innerverar m. trapezius, sternocefalicus, brachiocephalicus. Palpera nacken för att upptäcka muskelatrofier.

Question 597

XII Hypoglossus Ansvarar för..............................

Answer 597

XII Hypoglossus Ansvarar för tungans motorik. Undersök tungan genom att titta på den tex då patienten slickar sig om nosen (de flesta patienter brukar slicka sig om nosen direkt efter att man öppnat deras mun). Lägg ev. lite mat på nosen, känn på tungan. Leta efter atrofi, assymetri eller att tungan devierar åt ena hållet.

Question 598

Posturala reaktioner: Testar banor som verkar för att upprätthålla....................................................Kräver inverkan av både ................ och .............. banor så väl som inverkan från ...................... och ..................

Answer 598

Posturala reaktioner: Testar banor som verkar för att upprätthålla en normal kroppsställning. Kräver inverkan av både motoriska och sensoriska banor så väl som inverkan från cerebrum och cerebellum.

Question 599

Banorna passerar ...................... på väg till cerebrum och cerebellum. Nedsatt postural reaktion ses ...............lateralt vid hjärnstamsskador och...................lateralt vid cerebrumskador.

Answer 599

Banorna passerar hjärnstammen på väg till cerebrum och cerebellum. Nedsatt postural reaktion ses ipsilateralt vid hjärnstamsskador och kontralateralt vid cerebrumskador.

Question 600

OBS! Skilj på reflex och reaktion, en reaktion är ................. (når........................).

Answer 600

OBS! Skilj på reflex och reaktion, en reaktion är medveten (når cortex).

Question 601

Positionsreaktion: Undersöker .............................. (sensoriska receptorer finns i hud, leder och muskler) vilket betyder patientens........................... var extremiteterna är belägna och dess rörelse i luften.

Answer 601

Positionsreaktion: Undersöker proprioceptionen (sensoriska receptorer finns i hud, leder och muskler) vilket betyder patientens medvetna uppfattning om var extremiteterna är belägna och dess rörelse i luften. Undersöks genom att placera tassen med ovansidan mot underlaget, patienten ska omedelbart ställa tassen rätt. Undersöks både fram och bak. Patienten måste vara väl balanserad med stöd under fram- respektive bakben. Tänk på att den kan vara svårtolkad på en patient som har ont eller är undergiven. Dessutom svår att undersöka på katter som ogillar att man tar i deras tassar. Man kan även undersöka proprioceptionen genom att lägga ett papper under ena tassen och därefter långsamt föra pappret åt sidan ut ifrån kroppen, patienten ska då föra tillbaka benet .

Question 602

Hoppningsreaktion: Man testar om patienten märker att tyngden förskjuts. Beroende på patientens storlek lyfter man antingen upp ett eller tre ben för att sedan förskjuta tyngden så att hunden kommer att hoppa i sidled på det ben som står kvar på marken. Jämför alltid de två frambenen med varandra och de två bakbenen med varandra. Dålig, långsam initiering (reaktionstid) talar för ett ................(.....................) problem. Dålig, svag hoppning talar för ett ....................... problem. Detta är ett bra test på katter.

Answer 602

Hoppningsreaktion: Man testar om patienten märker att tyngden förskjuts. Beroende på patientens storlek lyfter man antingen upp ett eller tre ben för att sedan förskjuta tyngden så att hunden kommer att hoppa i sidled på det ben som står kvar på marken. Jämför alltid de två frambenen med varandra och de två bakbenen med varandra. Dålig, långsam initiering (reaktionstid) talar för ett sensorisk (proprioceptivt) problem. Dålig, svag hoppning talar för ett motoriskt problem. Detta är ett bra test på katter.

Question 603

Skottkärra: Bakbenen lyfts upp och patenten förs framåt så att den går med frambenen. Tyngden förskjutas på detta sätt framåt och svaghet i frambenen kan upptäckas. Titta efter assymetri, dysmetri och nedsatt koordination. Nedsatt proprioception i ...................... ses tidigare än med proprioceptionstest. Kan göras med upplyft huvud för att ta bort ev. visuell kompensation. Bra test på katt.

Answer 603

Skottkärra: Bakbenen lyfts upp och patenten förs framåt så att den går med frambenen. Tyngden förskjutas på detta sätt framåt och svaghet i frambenen kan upptäckas. Titta efter assymetri, dysmetri och nedsatt koordination. Nedsatt proprioception i frambenen ses tidigare än med proprioceptionstest. Kan göras med upplyft huvud för att ta bort ev. visuell kompensation. Bra test på katt.

Question 604

Placeringsreaktion, visuell och taktil: Stötta patienten under buken, för den mot en bordskant. Patienten ska vid den visuella undersökningen sätta upp tassarna på kanten innan bordet nuddar benen. I detta test kan man fånga upp tecken på nedsatt syn. Vid den taktila undersökningen får inte patienten se bordet, när tassarna nuddar bordskanten så ska patienten omedelbart sätta tassarna på bordet.

Answer 604

Placeringsreaktion, visuell och taktil: Stötta patienten under buken, för den mot en bordskant. Patienten ska vid den visuella undersökningen sätta upp tassarna på kanten innan bordet nuddar benen. I detta test kan man fånga upp tecken på nedsatt syn. Vid den taktila undersökningen får inte patienten se bordet, när tassarna nuddar bordskanten så ska patienten omedelbart sätta tassarna på bordet.

Question 605

Rättningsreaktion: Låt patienten hänga fritt i luften eller resa sig från liggande på sidan. Vid ................. syndrom ser man ofta att kroppen vrider sig åt den ........................... då de hänger fritt. Liggandes på sidan ska de resa sig med huvudet först, sen bålen och sist bakkroppen, vid ..................... syndrom har patienten ofta väldigt svårt att resa sig upp om de ligger på den ..............sidan.

Answer 605

Rättningsreaktion: Låt patienten hänga fritt i luften eller resa sig från liggande på sidan. Vid vestibulära syndrom ser man ofta att kroppen vrider sig åt den sjuka sidan då de hänger fritt. Liggandes på sidan ska de resa sig med huvudet först, sen bålen och sist bakkroppen, vid vestibulära syndrom har patienten ofta väldigt svårt att resa sig upp om de ligger på den sjuka sidan.

Question 606

Sträckar/stöt reaktion (extensor postural thrust): Lyft upp patienten och för den mer med bakbenen mot underlaget. När tassarna nuddar golvet ska djuret sträcka ut hasorna och ta några steg bakåt för att återfinna kroppsbalansen. Även här tittar men efter assymetri, dåligt koordinerade rörelser och dysmetri.

Answer 606

Sträckar/stöt reaktion (extensor postural thrust): Lyft upp patienten och för den mer med bakbenen mot underlaget. När tassarna nuddar golvet ska djuret sträcka ut hasorna och ta några steg bakåt för att återfinna kroppsbalansen. Även här tittar men efter assymetri, dåligt koordinerade rörelser och dysmetri.

Question 607

Hemiwalking, hemistanding: Ena sidans fram- och bakben lyfts upp nära bålen. Djuret puttas framåt eller åt sidan. Detta är ett bra test på patienter med skador i ................... De har en tämligen normal gång men nedsatta .................. reaktioner i både fram och bakben på den sida ....................lateralt om skadan. Bör undvikas på djur med grav ataxi eller pares.

Answer 607

Hemiwalking, hemistanding: Ena sidans fram- och bakben lyfts upp nära bålen. Djuret puttas framåt eller åt sidan. Detta är ett bra test på patienter med skador i storhjärnan. De har en tämligen normal gång men nedsatta posturala reaktioner i både fram och bakben på den sida kontralateralt om skadan. Bör undvikas på djur med grav ataxi eller pares.

Question 608

Spinala reflexer: Testar de motoriska och sensoriska komponenterna i ....................bågen. Ingen påverkan från ...................... Testas helst på djur som ligger ner.

Answer 608

Spinala reflexer: Testar de motoriska och sensoriska komponenterna i reflexbågen. Ingen påverkan från hjärnan. Testas helst på djur som ligger ner.

Question 609

Extensor carpi radialis reflex: Muskeln extensor carpi radialis sträcker ............. och innerveras av n. ............. som har sitt ursprung i ryggmärgssegmentet C....-T...... Reflexhammaren slås mot muskelbuken straxt distalt om armbågen, carpus hålls lätt böjd, ger en extension av carpus.

Answer 609

Extensor carpi radialis reflex: Muskeln extensor carpi radialis sträcker carpus och innerveras av n. radialis som har sitt ursprung i ryggmärgssegmentet C7-T1. Reflexhammaren slås mot muskelbuken straxt distalt om armbågen, carpus hålls lätt böjd, ger en extension av carpus.

Question 610

Biceps brachii och triceps reflexer: Dessa reflexer är mer opålitliga och går inte alltid att få fram på normala individer. Biceps brachii innerveras av n. muskulocutaneus och har sitt ursprung i ryggmärgsegment C....-C..... Ett finger placeras över den distala delen av biceps brachii och brachialis muskel i höjd med armbågen. Genom att slå med reflexhammaren på fingret kan man få fram reflexen som gör att armbågen böjs något eller att man känner att biceps muskeln kontraheras. Triceps innerveras av n. radialis och har sitt ursprung i ryggmärgssegment C...-T... Tricepsreflexen stimuleras genom att slå med reflexhammaren på tricepssenan proximalt om dess ursprung på olecranon. Den önskade reaktionen är att armbågen sträcks.

Answer 610

Biceps brachii och triceps reflexer: Dessa reflexer är mer opålitliga och går inte alltid att få fram på normala individer. Biceps brachii innerveras av n. muskulocutaneus och har sitt ursprung i ryggmärgsegment C6-C8. Ett finger placeras över den distala delen av biceps brachii och brachialis muskel i höjd med armbågen. Genom att slå med reflexhammaren på fingret kan man få fram reflexen som gör att armbågen böjs något eller att man känner att biceps muskeln kontraheras. Triceps innerveras av n. radialis och har sitt ursprung i ryggmärgssegment C7-T1. Tricepsreflexen stimuleras genom att slå med reflexhammaren på tricepssenan proximalt om dess ursprung på olecranon. Den önskade reaktionen är att armbågen sträcks.

Question 611

Patellarreflex: M. quadriceps innerveras av n. ........... och har sitt ursprung i ryggmärgssegment L....-L.... Reflexhammaren slås lätt mot patellas raka band varvid knäleden sträcks. Patellarreflexen kan vara nedsatt eller saknas på äldre individer och individer med tidigare knäskador. Vid skador på n............. eller L....-S.... kan ......reflexi ses beroende på nedsatt kraft i de muskler som böjer knäet, sk psudohyperreflexi.

Answer 611

Patellarreflex: M. quadriceps innerveras av n. femoralis och har sitt ursprung i ryggmärgssegment L4-L6. Reflexhammaren slås lätt mot patellas raka band varvid knäleden sträcks. Patellarreflexen kan vara nedsatt eller saknas på äldre individer och individer med tidigare knäskador. Vid skador på n.ischiadicus eller L6-S2 kan hyperreflexi ses beroende på nedsatt kraft i de muskler som böjer knäet, sk psudohyperreflexi.

Question 612

Böjreflexen: Undersöks på både fram- och bakben. I frambenet utvärderar denna reflex ryggmärgsegment C....-T..., plexus ........ samt .................nerver (axillaris, musculocutaneus, medianus och ulnaris nerverna). I bakbenet utvärderar denna reflex ryggmärssegment L....-S.... samt .......nerver (femoralis och ischiadicus). Denna reflex undersöks med patienten liggandes på sidan. Stimulering eller lätt nyp av huden mellan trampdynorna orsakar böjning av benet. Både mediala och lateral tån testas. Vid undersökning ska alla leder i benet ska böjas.

Answer 612

Böjreflexen: Undersöks på både fram- och bakben. I frambenet utvärderar denna reflex ryggmärgsegment C6-T2, plexus brachialis samt perifera nerver (axillaris, musculocutaneus, medianus och ulnaris nerverna). I bakbenet utvärderar denna reflex ryggmärssegment L4-S2 samt perifera nerver (femoralis och ischiadicus). Denna reflex undersöks med patienten liggandes på sidan. Stimulering eller lätt nyp av huden mellan trampdynorna orsakar böjning av benet. Både mediala och lateral tån testas. Vid undersökning ska alla leder i benet ska böjas.

Question 613

Förväxla inte böjreflexen med smärtsensibilitet. Ett djur som saknar smärtsensibilitet ................ böjreflex. Smärtsensibilitet kräver att djuret visar att det känner genom att morra, gnälla eller titta på tassen som vi nyper i.

Answer 613

Förväxla inte böjreflexen med smärtsensibilitet. Ett djur som saknar smärtsensibilitet kan ha böjreflex. Smärtsensibilitet kräver att djuret visar att det känner genom att morra, gnälla eller titta på tassen som vi nyper i.

Question 614

Korsad extensor reflex: När man testar böjreflexen ska det kontralaterala benet även observeras. En .................... av detta kontralaterala ben indikerar en ............-skada.

Answer 614

Korsad extensor reflex: När man testar böjreflexen ska det kontralaterala benet även observeras. En extension av detta kontralaterala ben indikerar en UMN-skada.

Question 615

Tibialis cranialis reflex: Tibialis cranialis innerveras av n. peroneus och har sitt ursprung i ryggmärgssegment L...-S... Reflexen stimuleras genom att slå med reflexhammaren på den proximala delen av tibialis cranialis muskeln. Hasen ska då böjas.

Answer 615

Tibialis cranialis reflex: Tibialis cranialis innerveras av n. peroneus och har sitt ursprung i ryggmärgssegment L6-S1. Reflexen stimuleras genom att slå med reflexhammaren på den proximala delen av tibialis cranialis muskeln. Hasen ska då böjas.

Question 616

Perinealreflex: Huden kring perineum innerveras av n. .................. som har sitt ursprung i ryggmärgssegment ....-....... Nyp i huden vid anus eller perineum orsakar .......... av sfinkter. Vanligtvis ses även .......... av svansen och ......... av vulva.

Answer 616

Perinealreflex: Huden kring perineum innerveras av n. pudendus som har sitt ursprung i ryggmärgssegment S1-S3 Nyp i huden vid anus eller perineum orsakar kontraktion av sfinkter. Vanligtvis ses även flexion av svansen och uppdragning av vulva.

Question 617

Panniculus reflex: Denna reflex undersöks genom att nypa i huden på ovansidan av ryggen mellan T...... och L.....-.... Reflexen saknas i ...... och ................ Stimulering av denna reflex gör att muskeln .................. det område där huden stimuleras .......................... Ett normalt svar ger en muskelsammandragning på båda sidor om ryggraden. Sensoriska nerver går in i ryggmärgen ............ ryggmärgssegment .......... om där man nyper i huden. Reflexen kan saknas .........lateralt och kan ses vid påverkan på plexus brachialis. Panniculus reflexen saknas ibland på normala individer.

Answer 617

Panniculus reflex: Denna reflex undersöks genom att nypa i huden på ovansidan av ryggen mellan T2 och L4-5. Reflexen saknas i hals och bäckenregionen. Stimulering av denna reflex gör att muskeln precis under det område där huden stimuleras drar ihop sig. Ett normalt svar ger en muskelsammandragning på båda sidor om ryggraden. Sensoriska nerver går in i ryggmärgen 2-4 ryggmärgssegment kranialt om där man nyper i huden. Reflexen kan saknas ipsilateralt och kan ses vid påverkan på plexus brachialis. Panniculus reflexen saknas ibland på normala individer.

Question 618

Smärtsensibilitet: Ytlig smärta bedöms genom att nypa med peang i simhuden. Djup smärta bedöms genom att nypa med peng över ........ och orsaka smärta i ........ Positiv respons innebär ............. från djuret med blick, huvudvridning, gnäll eller försök att bitas.

Answer 618

Smärtsensibilitet: Ytlig smärta bedöms genom att nypa med peang i simhuden. Djup smärta bedöms genom att nypa med peang över tån och orsaka smärta i periostet. Positiv respons innebär medveten reaktion från djuret med blick, huvudvridning, gnäll eller försök att bitas.

Question 619

Kan totalparalyserade djur visa smärtsensibilitet?

Answer 619

Totalparalyserade djur kan visa att de känner genom att ändra ansiktsuttryck, få stora pupiller eller orolig blick.

Question 620

Schiff-Sherrington: Kan ses vid akuta allvarliga skador i .......... eller främre ............ Ger ............. av frambenen, ibland sträcks även huvudet ....... kombinerat med ........ i bakbenen. Beror på att de............. impulserna bakifrån inte når fram. Kranialnervsfunktionen, de posturala reaktionerna samt de spinala reflexerna graderas som normala eller nedsatta. Reflexerna kan även bedömas som överdrivna. Ett vanligt bedömningssätt kan se ut så att en normal reflex eller reaktion graderas 0, en utebliven reflex eller reaktion graderas –2 och en överdriven upp till +2

Answer 620

Schiff-Sherrington: Kan ses vid akuta allvarliga skador i bröst eller främre ländryggen. Ger extension av frambenen, ibland sträcks även huvudet bakåt kombinerat med paralys i bakbenen. Beror på att de hämmande impulserna bakifrån inte når fram. Kranialnervsfunktionen, de posturala reaktionerna samt de spinala reflexerna graderas som normala eller nedsatta. Reflexerna kan även bedömas som överdrivna. Ett vanligt bedömningssätt kan se ut så att en normal reflex eller reaktion graderas 0, en utebliven reflex eller reaktion graderas –2 och en överdriven upp till +2

Question 621

Lokalisation: 1. Hur är de spinala reflexerna? Denna fråga ska ge oss svaret på om symtomen är orsakade av ett problem i det perifera (..........., ........) eller det centrala nervsystemet (......,.......).

Answer 621

Denna fråga ska ge oss svaret på om symtomen är orsakade av ett problem i det perifera (nerver, muskler) eller det centrala nervsystemet (hjärna, ryggmärg).

Question 622

Skador i det perifera nervsystemet kan ge symtom som onormal ......, ........, onormal ............ och onormala ................ nedsatt ................och muskel.......och nedsatta ........... Med nedsatta reflexer i alla ......... (och kanske även nedsatta kranialnerver) förekommer ett generellt ................ problem.

Answer 622

Skador i det perifera nervsystemet kan ge symtom som: onormal gång, pares, onormal proprioception onormala posturala reaktioner, nedsatt muskeltonus muskelatrofi nedsatta reflexer. Med nedsatta reflexer i alla fyra ben (och kanske även nedsatta kranialnerver) förekommer ett generellt LMN problem.

Question 623

2. Hur fungerar kranialnerverna? Nedsatta kranialnerver ses vanligen vid problem i ................ Skador i storhjärnan ger vanligen symtom som .....,........och................... Gången är sällan påverkad men man kan se passgång och tvångsmässig gång. Ger nedsatta posturala reaktioner. Skador i lillhjärnan ger symtom som hypermetrisk (överdriven ) gång, intentionstremor och ataxi. Skador i hjärnstammen ger symtom som nedsatt vakenhet, pares, multipla kranialnervsbortfall.

Answer 623

Nedsatta kranialnerver ses vanligen vid problem i hjärnan. Skador i storhjärnan ger vanligen symtom som beteendeförändringar, nedsatt vakenhet, kramper. Gången är sällan påverkad men man kan se passgång och tvångsmässig gång. Ger nedsatta posturala reaktioner. Skador i lillhjärnan ger symtom som hypermetrisk (överdriven ) gång, intentionstremor och ataxi. Skador i hjärnstammen ger symtom som nedsatt vakenhet, pares, multipla kranialnervsbortfall.

Question 624

3. Förekommer head tilt? Head tilt är det viktigaste symtomet vid vestibulära syndrom. Andra vanliga symtom vid vestibulära sjukdomar är ................................(3). Vid perifera vestibulära syndrom är positionsreaktionerna ......................

Answer 624

Head tilt är det viktigaste symtomet vid vestibulära syndrom. Andra vanliga symtom vid vestibulära sjukdomar är ataxi, nystagmus, strabismus (ventral). Vid perifera vestibulära syndrom är positionsreaktionerna normala.

Question 625

4. Hur är de posturala reaktionerna och reflexerna? För att lokalisera problemet inom ryggmärgen så kan den delas in i fyra delar. Vilka?

Answer 625

C1-C5, C6-T2, T3-L3 och L4-S3. Resultatet av de posturala reaktionerna och de spinala reflexerna hjälper att lokalisera problemet till någon av dessa fyra kategorier.

Question 626

Generalised decreased spinal reflexes = yes: CNS or PNS?

Answer 626

PNS (alpha-motorneuron, nerval root, peripheral nerve, neuromuscular junction, muscle)

Question 627

Generalised decreased spinal reflexes = no: CNS or PNS.

Answer 627

CNS

Question 628

CNS: abnomrla treatening reflex and/or function of the cranial nerves = no: Brain or spinal cord?

Answer 628

Spinal cord

Question 629

Spinal cord: proprioceptive reactions abnormal in all four limbs =Yes. Which segment?

Answer 629

C1-T2

Question 630

Spinal cord: proprioceptive reactions abnormal in all four limbs = No. Which segment?

Answer 630

T2 - S3

Question 631

C1-T2: UMN thoracic and pelvis limbs. Which segments?

Answer 631

C1-C5

Question 632

C1-Th2: LMN thoracic and UMN pelvic limb. Which segments?

Answer 632

C6-T2

Question 633

Th2-S3: Postural reactions abnormal just in the pelvic limbs. UMN. Which segments?

Answer 633

Th3-L3

Question 634

Th2-S3: Postural reactions abnormal just in the pelvic limbs. LMN. Which segments?

Answer 634

L3-S3

Question 635

CNS: abnomrla treatening reflex and/or function of the cranial nerves = yes. Brain or spinal cord?

Answer 635

Brain

Question 636

CNS: Brain:. Gait normal. Where is the insult?

Answer 636

Cerebrum

Question 637

CNS: Brain. Gait onormal. but hypermetria and intention tremor is present. Where is the insult?

Answer 637

Cerebellum.

Question 638

CNS: Brain. Gait onormal. but hypermetria and intention tremor is lacking, but tetra-, hemiparesis present: Where is the insult?

Answer 638

Brain stem

Question 639

CNS: Brain. Gait onormal. but hypermetria and intention tremor: yes/no. Head tilt yes. Placing reaction normal.

Answer 639

Peripheral vestibular

Question 640

CNS: Brain. Gait onormal. but hypermetria and intention tremor: yes/no. Head tilt yes. Not placing reaction normal.

Answer 640

Central vestibular

Question 641

VITAMIN D:

Answer 641

Vaskulära sjukdomar Inflammatoriska sjukdomar Traumatiska sjukdomar Anomalier Metaboliska sjukdomar Idiopatiska sjukdomar Neoplastiska sjukdomar Degenerativa sjukdomar

Question 642

Diagnostiska hjälpmedel: Röntgen, ger ibland värdefull information om sjukliga processer i skelett, leder och disker intill nervsystemet, även av värde då neoplasi misstänks (finns neoplasier på andra ställen i kroppen?) Blodprov och urinprov, indicerade vid misstanke om metabolisk sjukdom, i övrigt av begränsat värde med anledning av blod hjärnbarriären CT/MRT CT ger bäst information om skelettskador, MRT ger bäst information om mjukdelsskador CSF, indicerat ffa vid misstanke om inflammatorisk/infektiös process Myelografi, används för att utvärdera ryggmärgen Elektrodiagnostik EMG/ neurografi, för utredning av förändringar i det perifera nervsystemet Biopsier nerv/muskel, för utredning av förändringar i det perifera nervsystemet

Answer 642

Diagnostiska hjälpmedel: Röntgen, ger ibland värdefull information om sjukliga processer i skelett, leder och disker intill nervsystemet, även av värde då neoplasi misstänks (finns neoplasier på andra ställen i kroppen?) Blodprov och urinprov, indicerade vid misstanke om metabolisk sjukdom, i övrigt av begränsat värde med anledning av blod hjärnbarriären CT/MRT CT ger bäst information om skelettskador, MRT ger bäst information om mjukdelsskador CSF, indicerat ffa vid misstanke om inflammatorisk/infektiös process Myelografi, används för att utvärdera ryggmärgen Elektrodiagnostik EMG/ neurografi, för utredning av förändringar i det perifera nervsystemet Biopsier nerv/muskel, för utredning av förändringar i det perifera nervsystemet