Neurological examination

Question 1

What are the specific regions of the nervous system

Answer 1

Attempts should be made to explain all the abnormal findings of the neurological exam by a single lesion within one of the following specific regions of the nervous system:

- focal forebrain, brainstem, cerebellum

- C1-C5 spinal cord segments

- C6-T2 spinal cord segments

- T3-L3 spinal cord segments

- L4-L6 spinal cord segments

- L7-S3 spinal cord segments

- peripheral nerve, neuromuscular junction, muscle

Question 2

When a single lesion cannot explain all the abnormal findings identified, what can you conclude

Answer 2

If a single lesion cannot explain all the abnormal findings identified, the lesion localisation is considered as being multifocal or diffuse

Question 3

What are the different state of consciousness that can be observed during the hands-off examination

Answer 3

Disturbances in the state of consciouness are classified in order of severity as:
- depression (mentally dull but still conscious)
- lethargy
- obtundation
- stupor (semi-coma) (mostly unconscious but can be aroused with external stimuli, but quickly lapses back into a state of unconsciousness)
- coma (cannot be aroused from a state of unconsciousness by external stimuli)

Question 4

When you observe an alteration of the state of consciousness, what can you conclude

Answer 4

As a rule, altered states of consciousness relate either to:
- a diffuse lesion or widespread multifocal lesions of both central hemispheres
- or a focal lesion affecting the ascending reticular activating system (ARAS) of the brainstem

Question 5

What is associated with a head tilt

Answer 5

vestibular disorder

Question 6

What is associated with a head turn

Answer 6

An ipsilateral forbrain lesion

Question 7

What is associated with ventroflexion of the neck

Answer 7

A neuromuscular disorder or severe cervical spinal cord grey matter lesion

Question 8

What is the position of the tail in cats suffering a significant loss of balance

Answer 8

Cats often carry their tail elevated straight dorsally when they are suffering a significant loss of balance

Question 9

Give a definition of ataxia

Answer 9

Ataxia is an uncoordinated gait arising from:
- a peripheral nerve or spinal cord lesion (general proprioceptive ataxia)

- a vestibular lesion (vestibular ataxia)

- a cerebellar lesion (cerebellar ataxia)

Question 10

What is the definition of paresis

Answer 10

Paresis is defined as:
- a loss of ability to support weight (lower motor neuron disease)

- or inability to generate a gait (upper motor neuron disease)

Question 11

What are the two postural reactions pathways

Answer 11

Afferent arm components:
- joint proprioceptor
- peripheral sensory nerve
- spinal cord and brainstem ascending pathway
- contralateral forebrain

Efferent arm components:
- contralateral forebrain
- descending motor pathways within the brainstem and spinal cord
- peripheral motor nerve and skeletal muscle

Question 12

What are the three postural reactions tests used in cats

Answer 12

Hopping
Wheelbarrowing
Tactile placing

Paw position testing can be very difficult to assess in cats

Question 13

What is evaluated by the thoracic limb withdrawal reflex

Answer 13

In the thoracic limb, the withdrawal reflex evaluates:
- the integrity of the C6-T2 spinal cord segments (and associated nerve roots)

- brachial plexus

- peripheral nerves (radial, axillary, musculocutaneous, median and ulnar)

- the muscles innervated

Question 14

What is evaluated by the pelvic withdrawal reflex

Answer 14

In the pelvic limb, the withdrawal reflex evaluates:
- the integrity of the L4-S1 spinal cord segments (and associated nerve roots)

- the femoral and sciatic nerves

- the muscles innervated

Question 15

When does the patellar reflex appear exaggerated

Answer 15

A lesion cranial to the L4 spinal cord segment can cause a normal or exaggerated reflex
- in the absence of other neurological deficits, it has little clinical signification

The patellar reflex can also appear hyperreflexic in a cat with a sciatic nerve or L6-S1 spinal cord segment lesion
- this pseudohyperreflexia is a result of decreased tone in the muscles that flex the stiffle and normally counteract stifle extension

Question 16

What are the afferent and efferent arms of the menace response

Answer 16

Afferent arm:
- the retina
- optic nerve (CN II)
- contralateral optic tract
- contralateral forebrain

Efferent arm:
- contralateral forebrain
- ipsilateral cerebellum
- ipsilateral facial nerve (CN VII)

Question 17

Explain the pathways of the pupillary light reflex

Answer 17

The size of the pupils represents a balance between the parasympathetic system, which is responsive to the amount of light entering the eye, and the sympathetic system, which is responsive to the emotional state of the cat
- the parasympathetic component of the oculomotor nerve (CN III) is involved in the control of pupillary constriction

- the sympathetic system dilates the pupil during periods of stress and fear, and in response to painful stimuli
     - it will also keep the eyeball protruded, the palpebral fissure widened and the third eyelid retracted

Question 18

When you notice a modification in the cat’s behavior despite normal blood test results, where can you localize the problem

Answer 18

Neurological causes for alterations in behavior (e.g., head-pressing into corners, howling uncontrollably) include lesions within the limbic system and extrapyramidal nuclei

Question 19

Whar are the main categories of problems leading to an anomaly in the cat’s posture

Answer 19

Alterations in the cat’s posture may be due to:
- neurological disease
- weakness
- musculoskeletal pain

Question 20

What are the particular posture adopted by weak cats

Answer 20

Weak cats will often adopt particular postural abnormalities:
- passive neck ventroflexion (presumed to be due to the lack of a nuchal ligament)

- upright posture with limbs tucked under the body

- frequent adoption of sternal recumbency with head placed on forelimbs or table

- inability to retract claws passively

Question 21

What is opisthotonos

Answer 21

This body position is characterized by adoption of lateral recumbency with extension of the head and neck and rigid extension of the forelimbs

This posture often occurs with lesions of:
- the rostral cerebellum
- caudal midbrain
- other structures within the caudal fossa

Question 22

What is decerebrate rigidity

Answer 22

Decerebrate rigidity is characterized by all four limbs held in rigid extension generally resulting from a lesion of the flexor motor tracts that traverse midbrain and pons
- usually coma or stupor are also present

Question 23

What is decerebellate rigidity

Answer 23

Decerebellate rigidity occurs when there is an isolated rostral cerebellar lesion

This position differs from decerebrate rigidity in that the hind limbs are mostly flexed and the level of consciousness is not impaired (if this is the only lesion present)

Question 24

What is Schiff-Sherrington posture

Answer 24

Schiff-Sherrington posture is characterized by increased extensor tone of the thoracic limbs and flaccid paralysis of the pelvic limbs
- head and neck are not altered

This posture is seen after acute thoracolumbar (T3-L3) spinal coord lesions
- it is rarely seen in cats

Question 25

If the cat has gait abnormalities but is not ataxic, what can you conclude

Answer 25

If the cat has gait abnormalities but is not ataxic, we can consider the presence of musculoskeletal disease or disorders of the peripheral nervous system

Question 26

What are the characteristics of proprioceptive (sensory) ataxia

Answer 26

This is the most common form of ataxia seen in small animal practice The proprioceptive pathways lie at the peripheral aspects of the spinal cord, and are thus easily damaged by external compressive lesions such as tumors or ruptured intervertebral discs Hallmarks of proprioceptive ataxia are: - a wide-based stance - prolongation of stride length - stumbling or knuckling whilst walking or performong postural reactions The most common cause of proproceptive ataxia is spinal cord disease - brainstem disease may produce marked proprioceptive ataxia, however disease in this location is usually accompanied by an altered level of consciousness and/or cranial nerve deficits

Question 27

What are the characteristics of vestibular ataxia

Answer 27

Hallmarks of vestibular ataxia are: - presence of a head tilt towards the side of the lesion - the animal will often lean, fall or roll towards the side of the lesion

Question 28

What are the characteristics of cerebellar ataxia

Answer 28

Unilateral cerebellar disease produces ipsilateral hyper-metric ataxia with no proprioceptive deficits or loss of strength

Question 29

What is the objective of postural reaction tests (hemi-walking, wheelbarrowing and hopping)

Answer 29

Postural reactions are tests used to detect subtle problems with limb strength and coordination Poor initiation of the movement indicates proprioceptive problems Poor follow-through indicate motor deficits (paresis)

Question 30

What are the clinical signs associated with a lesion of CN I

Answer 30

CN I is olfactory CN The owner may note that the cat cannot detect the presence of food The most common causes of anosmia are nasal cavity diseases - Brain disease is rare with head trauma the most frequent cause

Question 31

What are the clinical signs associated with a lesion of CN II

Answer 31

CN II is optic CN Clinical signs include: - blindness - absence of PLR - absence of menace response

Question 32

What are the clinical signs associated with a lesion of CN III

Answer 32

CN III is oculomotor CN Clinical signs of oculomotor nerve dysfunction include: - lateral and ventral strabismus due to paralysis of the extra-ocular muscles - ptosis due to paralysis of the levator palpebri muscle - dilated pupil that is unresponsive to a light stimulus

Question 33

What are the clinical signs associated with CN IV

Answer 33

CN IV is trochlear CN Clinical signs with trochlear nerve dysfunction include: - presence of a dorsomedial strabismus

Question 34

What are the clinical signs associated with CN V

Answer 34

CN V is trigeminal CN Clinical signs of trigeminal nerve dysfunction include: - loss of ipsilateral facial sensation - corneal and palpebral reflexes may be diminished - bilateral loss of motor function of CN V may result in mandibular paralysis (dropped jaw) - atrophy of masseters and temporalis muscles

Question 35

What are the clinical signs associated with a lesion of CN VI

Answer 35

CN VI is abducens CN Clinical signs of dysfunction of the abducens nerve include: - paralysis of the lateral rectus resulting in a medial strabismus - the affected eye cannot be abducted fully in response to the corneal reflex

Question 36

What are the clinical signs associated with a lesion of CN VII

Answer 36

CN VII is facial CN Clinical signs of facial nerve dysfunction include: - ipsilateral facial paresis or paralysis - the palpebral fissure on the affected side may be slightly wider and fails to close in response to stimulation via the corneal or palpebral reflexes - exposure keratitis on affected side - because of the close anatomical loccation of the facial and the vestibulococlear nerves at their brainstem and also their course through the petrosal bone they are often affected simultaneously by the same lesion (e.g., otitis interna)

Question 37

What are the clinical signs associated with a lesion of CN VIII

Answer 37

CN VIII is the vestibulocochlear CN Dysfunction of the CN VIII include: - loss of hearing - presence of spontaneous nystagmus - lack of normal physiological nystagmus - positional strabismus

Question 38

What are the clinical signs associated with a lesion of CN IX, X XI

Answer 38

CN IX is the glossopharyngeal CN CN X is the vagus CN CN XI is the accessory CN Clinical signs of glossopharyngeal, vagus and accessory nerve dysfunction include: - varying degrees of dysphagia and difficulty with swallowing - the gag reflex is reduced or absent - paralysis of the laryngeal muscles - regurgitations may occur due to megaoesophagus

Question 39

What are the clinical signs associated with a lesion of CN XII

Answer 39

CN XII is hypoglossal CN Clinical signs of hypoglossal nerve dysfunction include: - paresis or paralysis of the tongue that may be ipsilateral in unilateral lesions -affected animals are unable to prehend food or water - unilateral lesion results in deviation of the tongue towards the side of the lesion

Question 40

What is the upper motor neuron and what is its function

Answer 40

The upper motor neuron is the motor system confined to the central nervous system It is responsible for: - the initiation of voluntary movements - the maintenance of postural tone against gravity and to establish the posture upon which voluntary activity can be performed - the control of muscular activity associated with visceral functions (i.e., respiratory, cardiovascular, ...) It can be divided into pyramidal and extra-pyramidal components

Question 41

Where are located the cell bodies of the pyramidal system

Answer 41

The cell bodies of the pyramidal system are located in the motor area of the frontal and parietal lobes of the cerebral cortex

Question 42

What is the extrapyramidal system

Answer 42

The extrapyramidal system consists of diverse groups of interconnected and functionally related neurological structures They work in conjunction with the pyramidal system and provide muscular tone to support the body against gravity and to recruit the spinal reflexes for the initiation of voluntary movement, by influencing the activity of the alpha and gamma motor neurons in the ventral column of the spinal cord

Question 43

Where are located the cell bodies of the extrapyramidal system

Answer 43

The cell bodies of the extrapyramidal system are located in nuclei dispersed throughout all the areas of the brain

Question 44

What is the site of the lesion for an UMN disease

Answer 44

Lesions that occur cranial to the reflex arc disconnect the reflex from inhibition that is normally supplied by the higher brain centers - signs are observed on the contralateral side of the body if the lesion is rostral to the junction between the midbrain and pons (tend to be less profound) - signs are observed ipsilateral if located caudal to the junction between midbrain and pons (tend to be more obvious and debilatating)

Question 45

What are the signs of UMN disease

Answer 45

Signs of UMN disease consist of: - exaggeration of myotatic reflexes or muscular clonus - paresis - spasticity - crossed extensor reflex - a distended bladder that is difficult to express ("upper motor neuron bladder")

Question 46

What is the lower motor neuron

Answer 46

The lower motor neuron is the efferent neuron of the peripheral nervous system that connects the CNS with a group of muscle cells or a gland The lower motor neuron is divided into three components: - the general somatic efferent system, which innervates striated voluntary skeletal muscle - the general visceral efferent system, which innervates the smooth muscle associated with blood vessels, visceral structures, glands and cardiac muscle (this is an involuntary system and represents the nerves of the autonomic nervous system) - the special visceral efferent system, which innervates striated muscles of visceral structures of the respiratory and digestive systems derived from branchial arch mesoderm

Question 47

Where are located the general somatic efferent neurones

Answer 47

These neurons are located throughout the entire spinal cord in the ventral column The axons of the general somatic efferent neurons leave the spinal cord in the ventral root

Question 48

Where are located the three sacral segments of the spinal cord in the cat

Answer 48

In the cat the three sacral segments are usually located over the body of L6 and the spinal cord ends at around L7 (the remainder of the spinal canal being occupied by the spinal nerves that make up the cauda equina)

Question 49

What are the clinical signs of LMN signs

Answer 49

Lesions within the lower motor neuron itself lead to loss of muscular function Signs of lower motor neuron disease consist of: - decreased or absent reflexes - paresis or paralysis - hypotonia or atonia of muscles - neurogenic atrophy - loss of anal tone - a distended bladder that is easy to express or has overflow incontinence ("lower motor neuron bladder)