Neuroanatomy Flashcards

Question

Primary cortical inputs into the hippocampus

Answer 1

Ventral Stream > unimodal (primarily visual) cortical areas > perirhinal cortex >lateral (anterior) entorhinal cortex > both HC CA1 and CA3 Dorsal Stream > Parietal and Frontal Association Areas > Parahippocampal cortex > Medial (posterior) Entorhinal Cortex > Both HC CA1 and CA 3 (see stucky page 35 for review) newer findings suggest that both the parahippocampal and perirhinal cortices have spatial and non-spatial cortical connections and communication occurs between the two areas, allowing both structures to access both types of information from the cortex prior to their interaction with the hippocampus. the posterior/medial medial entorhinal cortex receives a majority of its input from the parahippocampal cortex and "spatial" cortical regions. the posterior medial entorhinal cortex evidences greater spatial-specific function compared to the anterior lateral entorhinal cortex due to the presence of grid cells which encode for spatial location in the environment and communicate with the place cells of the hippocampus.

Answer 2

1. fibers from CA1, CA3, and subiculum project in the precommisural fornix to the lateral septal nucleus 2. subicular projections travel in the postcommisural fornix and terminate on the mammillary bodies or the anterior nucleus of the thalamus. (this was part of Papez circut to explain how the hypothalamus and cortex coordinate emotion-cognition interaction) 3. the hippocampus also projects to the amygdala, nucleus accumbens, other regions of the Basal Forebrain, and ventromedial hypothalamus. Papez circuit: remaining part after #2- is the medial limbic circuit. Perirhinal/Parahippocampal cortex > hippocampus > fornix pathway leads to mamillary bodies > takes mammillothalamic tract to anterior thalamus > cingulate gyrus > back to hippocampus via cingulum and parahippocampal cortex. Lateral Circuit: Perirhinal/Parahippocampal cortex > amygdala > ventral amygdalofugal pathway to Dorsomedial thalamus > orbitofrontal > amygdala via the uncinate fasciculus. can also go from PPC > straight to dorsomedial thalamus

Answer 3

amnesia occurs when both the lateral and medial limbic circuit are damaged. e.g., if lesions affect the fornix (medial circuit) and ventral amygdalofugal pathway (lateral circuit), severe amnesia occurs. if only one area is affected, affecting one pathway, a less severe memory disturbance results. studies suggest that structures within each of the two memory systems are highly interdependent, since damage to different parts of each system can cause apparently equivalent deficits and 2) that each system can, to a large extent, carry on the function of the other, since lesions affecting only one system can result in memory loss that is far less severe than if both systems are damaged. 4 primary conclusions: 1. damage to cortical and subcortical structures within the temporal lobe, whether focal or extensive, can result in amnesia. 2. amnesia most likely results from damage to both the hippocampally based medial limbic circuit and the amygdala-based lateral limbic circuit 3. damage to individual elements of these circuits can all result in amnesia, provided that both circuits are damaged 4. the hippocampus appears critical for episodic memory, whereas the amygdala appears more directly involved in emotional aspects of cognition, including emotional memory and assigning emotional significance to stimuli

Answer 4

(meaning "inner chamber" or "bedroom" in Greek) in addition to sensory information, the thalamus also conveys nearly all other inputs to the cortex, including motor inputs from the cerebellum and basal ganglia, limbic inputs, widespread modulatory inputs involved in behavioral arousal and sleep-wake cycles, and other inputs. important as a sensory relay nucleus but also has critical functions in higher cognitive processes including alertness, behavioral activation, and memory. comprised of nuclear groups separated in the ventral-dorsal and anterior-posterior places by a system of myelinated fiber tracks called the internal medullary lamina (IML). it is within the IML that memory-relevant fibers of the mammillothalamic tract and the ventral amygdalofugal pathways travel on their way to their terminations in the anterior and dorsomedial thalamic nuclei, respectively. -Amnesia is more associated with lesions affecting the internal medullary lamina and mammillothalamic tract. more posterior lesions that involve portions of the dorsomedial nucleus but spare the IML and mammillothalamic tract are not associated with amnesia

Answer 5

midline thalamic nuclei have connections with the hippocampus and are consistently damaged in patients with Wernicke-Korsakoff disease. Aside from impairing connections to the hippocampus, thalamic lesions may disconnect thalamic connections with the frontal lobes. it has also been proposed that restricted thalamic lesions in Wernickes might disconnect dorsomedial-frontal connections important for imposing cognitive structure on semantic memories resident in posterior cortex.

Answer 6

3rd major region essential for normal human memory function. It is the major source of cholinergic input throughout the brain. Damage here is associated with profound memory loss with confabulation, the latter of which is likely associated with neighboring frontal lobe damage. components include the septal area, diagonal band of Broca, nucleus accumbens septi, olfactory tubercle, substantia innominata (containing the nucleus basalis of Meynert), bed nucleus of the stria terminalis, and preoptic area.

Answer 7

thought that damage to cholinergic neurons in the basal forebrain from the hemorrhage (which project to both the medial and lateral limbic circuits) may be responsible. it may not be the size of basal forebrain lesions that matter for causing amnesia, but whether the lesion is situated to produce a cholinergic disconnection with memory-relevant structures in the diencephalic and medial temporal lobe memory systems.

Answer 8

Left hemisphere dominant for 95% of right-handers and in more than 60-70% of left-handers.

Answer 9

Affected areas: Wernicke's area and adjacent BA 37 (medial and lateral most caudal portion of temporal lobe- includes part of fusiform gyrus) ,39 (angular gyrus), and 40 (supramarginal gyrus) these areas are responsible for initial perceptual steps of language processing enabling phonological (sound-based) sequences to be identified and comprehended as words. damage produces a fluent aphasia (because motor-articulatory regions in the frontal lobe are intact) characterized primarily by a disturbance in comprehension (wernicke's aphasia).

Answer 10

articulation of speech sounds and production of words and sentences depends on a variety of regions including the face area of the primary motor cortex, but begins in Broca's area, which plans and activates sequences of speech sounds. damage to this region produces a nonfluent aphasia with relatively intact comprehension, known as Broca's aphasia and it's variants.

Answer 11

disturbance of repetition and spontaneous speech, phonemic paraphasia. Deficit: disconnection between sound patterns and speech production mechanisms. lesion location: arcuate fasciculus. Repetition of language requires that the phonological representations generated by processing in Wernicke's area be converted to motor-articulatory sequences and utterances in Broca's area. The two regions are connected by a large subcortical white matter pathway, the arcuate fasciculus, which is volumetrically larger in the left hemisphere than in the right. damage restricted to the arcuate fasciculus produces a disproportionate deficit in repetition, with relative sparing of comprehension and fluency, a syndrome known as conduction aphasia.

Answer 12

a large subcortical white matter pathway connecting Broca's and Wernicke's areas, which is volumetrically larger in the left hemisphere than in the right. damage restricted to the arcuate fasciculus produces a disproportionate deficit in repetition, with relative sparing of comprehension and fluency, a syndrome known as conduction aphasia.

Answer 13

defined as the use of tone, pitch, rhythm, and other vocal intonation patterns to convey both meaning (e.g., marking a question vs an exclamation) and emotion (e.g., marking specific states such as anger, sadness, or mirth) in language. Prosody is primarily processed in the right hemisphere, where focal leions can produce prosodic syndromes (aprosodias) that bear striking similarity to their contralateral language-based counterparts. E.g., damage to the inferior right frontal lobe produces a deficit in expressing emotional prosody in speech that is analogous to Broca's aphasia, while posterior temporal-parietal lesions produce a deficit in prosody comprehension with fluent production, akin to Wernicke's.

Answer 14

decreased speech production; sparse, halting speech, missing function words, syntactic deficits, right hemiparesis (often). Deficit: Impaired speech planning and production. Lesion: posterior aspect of third frontal convolution- BA 44,45 (damage to adjacent motor fibers may produce right hemiparesis)

Answer 15

decreased auditory comprehension, fluent speech, paraphasias, poor repetition and naming, may have right homonymous hemianopia Deficit: impaired representation of the sound structure of words. lesion location: BA 22. posterior half of the superior (first) temporal gyrus (geniculostriate white matter damage may produce right homonymous hemianopia)

Answer 16

decreased single word production, marked for common nouns; repetition and comprehension relatively intact. Deficit: impaired storage or access to lexicon. Lesion: Inferior parietal lobule or connections within perisylvian language areas; many other forms of aphasia evolve to anomia in recovery

Answer 17

disturbed spontaneous speech similar to Broca's; relatively preserved repetition and comprehension. Deficit: disconnection between conceptual word/sentence representations in perisylvian region and motor speech areas. Lesion: deep white matter tracts connecting broca's area to parietal lobe; usually caused by anterior watershed infarcts

Answer 18

disturbance in word comprehension with relatively intact repetition. Deficit: disturbed activation of word meanings despite normal recognition of auditorily presented words. Lesion: white matter tracts connecting parietal and temporal lobe. usually caused by posterior watershed infarcts.

Answer 19

damage to the interhemispheric crossing fibers in the splenium of the corpus callosum. these lesions prevent information that was appropriately perceived in the right hemisphere/left visual field from accessing the perisylvian language areas in the left hemisphere. can also cause color agnosia (color naming disturbances), and optic aphasia.

Answer 20

person cannot name a visually apprehended object but can demonstrate its use, presumably because more anterior callosal fibers connecting the intact visual areas to left hemisphere praxis mechanisms are intact.

Answer 21

the patient cannot understand language but can identify nonverbal sounds such as chirping birds or jingling keys. results from white matter disconnection of fibers from left and right auditory receptive areas (Heschel's gyrus, BA 41,42 in each hemisphere) from Wernicke's area in the left hemisphere.

Answer 22

an essential feature of cortical-subcortical interaction in a variety of cognitive domains. Cortical activity is modulated by connections from cortex, through inhibitory and excitatory structures in the basal forebrain and thalamus, and back to cortex as a way of engaging a cortical region needed for task performance or of inhibiting another region whose function would interfere with processing or compete for output. The process of activating cortical regions for task performance is known as selective engagement. cortex > striatum (caudate, putamen) > globus pallidus > thalamus >Back to cortex

Answer 23

The process of activating cortical regions for task performance, heavily involves the frontal lobe and subcortical interactions

Answer 24

1. orienting to stimuli- tuning of perceptual systems to incoming stimuli so that relevant information from sensory input can be selected for further processing. dependent on acetylcholine and involves a functional system consisting of the superior colliculus, pulvinar thalamic nucleus, posterior temporoparietal cortex, and a region within the frontal lobes known as the frontal eye fields (BA 8, involved in volitional control of eye movements). 2. alerting: a state of sensitivity to incoming stimuli. it is modulated by norepinephrine and depends primarily on ascending sensory inputs from the thalamus. 3. executive aspects of attention: executive attention involves monitoring and resolving conflicts among thoughts, feelings, and behaviors. it is primarily dependent on dopamine and involves key structures including the anterior cingulate cortex and DLPFC.

Answer 25

a combination of bottom-up and top-down influences. Sensory signals first arrive at superior colliculi and pulvinar for preprocessing in a "bottom-up" information processing that is biased toward salient environmental stimuli and is then sent to frontal and parietal cortices. In turn, "top-down" biases from parietal (which provides visuomotor frames of reference) and frontal lobe (which provides substrate for working memory and goal setting) are transmitted to colliculi, pulvinar, and frontal eye fields, such that any complex attentional act is a combo of bottom-up and top-down processes. research suggests a dorsal frontoparietal system forms the cortical substrate of top-down attention, whereas a more ventral frontoparietal system is involved in target detection in the sensory environment.

Answer 26

seminal work by Goldman-Rakic with primate studies. functionally separate working memory subsystems exist in the dorsolateral PFC. - a dorsal (spatial)-ventral (object-based) distinction appears to exist in frontal working memory systems just as it does in posterior cortex. - dorsal components of the frontal working memory system are preferentially connected to structures in the dorsal visual stream and vice-versa. Neuronal subpopulations in the dorsal prefrontal cortex (arcuate sulcus; BA46) code spatial information, whereas others in the ventral prefrontal cortex (inferior prefrontal convexity; BA12) are selectively active during object working memory tasks.

Answer 27

Main function in the CNS is the facilitation of attention, memory, and learning. Pharmacological blockade of central cholinergic transmission causes delirium and memory deficits. degeneration of cholinergic neurons in the basal forebrain may be one of the mechanisms for memory decline in Alzheimer's disease. 2 main origins: 1.) pontomesenchephalic region > projects to intralaminar nucleus of thalamus > then to widespread areas of the cortex. role: indirect excitation of thalamo-cortical projection. affects attention, memory, regulation of thalamic output 2. basal forebrain region (nucleus basalis of meynert; medial septum; nucleus of the diagonal band) > widespread cortical (meynert) and hippocampus (medial septum and diagonal band). Role is exciation/facilitation. affects attention, learning, and memory 2 subclasses of acetylcholine-containing receptors. 1. muscarinic: mediate the main cognitive effects attributed to cholinergic pathways, with effects on attention, learning, and memory. 2. nicotinic: trigger rapid neural and neuromuscular transmission within the sympathetic and parasympathetic nervous system and at the neuromuscular junction. drugs with strong anticholinergic properties (e.g., antihistamines, first-generation antipsychotics, and tricyclic antidepressents) thus may exert negative effects on cognitive performance in these areas, particularly when administered to elderly or others with reduced cognitive and or cerebral reserve.

Answer 28

2 origins: 1.locus coeruleus (small brainstem nucleus, latin for blue spot)> widespread cortical. role excitation/facilitation. affects attentional shifting; arousal 2. lateral tegmental area of pons and medulla > widespread cortical. role excitation/facilitation. affects mood; sleep-wake cycle these projections can be inhibitory or excitatory. has been called a "stress hormone," plays a role in attention, sleep-wake cycles, and mood and may have a modulating role in pain. it plays a role in neuropsychiatric disorders such as depression, bipolar disorder, and in anxiety disorders such as OCD. cholinergic and serotonergic activation can inhibit NE neurotransmission. drugs commonly prescribed for ADHD (methylphenidate [Ritalin, Concerta], amphetamine/dextroamphetamine [Adderall] increase levels of NE and dopamine, whereas atomoxetine (Strattera) is a specific norepinephrine reuptake inhibitor that only affects NE.

Answer 29

2 origins: 1. Rostral raphe nuclei of midbrain, pons, and medulla > forebrain (thalamus, basal ganglia, cortex). role is post-synaptic inhibition. affects mood and arousal plays a role in psychiatric syndromes including anxiety, depression, OCD, aggressive behavior, and certain eating disorders. 2. dorsal raphe >cerebellum, medulla, spinal cord. role is post-synaptic inhibition. affects pain, respiration, temperature, motor control. drugs affecting serotonin metabolism are commonly prescribed for depression, generalized anxiety, and social phobia. Some (e.g., fluoxetine [Prozac], sertraline [Zoloft] are serotonin-specific reuptake inhibitors, wheras others (e.g., venlafaxine [Effexor]) effect reuptake inhibition in the serotonergic and noradrenergic system. These drugs can be used in combo with serotonin 2A antagonists (e.g., trazodone [Desyrel], mirtazapine [Remeron], or other agents to treat refractory depression.

Answer 30

dopamine-containing neurons exist primarily in the substantia nigra pars compacta and in the ventral tegmental area of the midbrain. Projection system is generally organized into 3 separate subsystems: 1. Mesostriatal system arises from the substantia nigra pars compacta and projects to the striatum (caudate and putamen). this pathway is implicated in Parkinson's and dysfunction here can produce disabling motor and nonmotor symptoms. Often PD is treated with dopaminergic agonists. 2. Mesolimbic pathway originates in the VTA and projects to the medial temporal lobe, amygdala, cingulate gyrus, and nucleus accumbens. plays a key role in reward functions and has been implicated in addictive behavior. overactivity of this pathway has been associated with the positive symptoms of schizophrenia, such as delusions and hallucinations, which respond well to domaine-seratonin 2A antagonist drugs (e.g., clozapine [Clozaril}, quetiapine {seroquel], risperidone {Risperdal}). 3. Mesocortical system arises mainly from VTA and projects primarily to cortical regions of the frontal lobe. This system plays a key role in executive functions, working memory, top-down attention, and initiation of motor activity. dysfunction in this system can produce some of the negative symptoms of schizophrenia, as well as dysexecutive syndrome and bradykinesia.

Answer 31

GABA is one key inhibitory (rather than excitatory) transmitter of signicant importance to memory, anxiety/arousal, and neuromodulation. GABA-ergic neurons (widely distributed)participate in short- and long-range inhibitory projections that innervate many of the same areas as other neurotransmitters and provide counteracting inhibitory input. The balance of GABA-ergic influences, together with the action of other neurotransmitters, is a key basis of neuromodulation. It is generally believed that certain GABA-ergic neurons located in the reticular nucleus of the thalamus may be critical for gating thalamocortical interactions and for regulating sleep and arousal. Similarly, GABA-ergic neurons in the basal forebrain regulate attentional shifting and alternation between response-reinforcement contingencies. Many antianxiety drugs act to enhance GABA-ergic neurotransmission, thus offsetting abnormally strong excitatory influences in these disorders.

Answer 32

(widely distributed. role is post-synaptic excitation). this is the most abundant excitatory neurotransmitter in the brain. plays a key role in learning and memory, and the glutamatergic NMDA receptor is implicated in processes of long-term potentiation and synaptic plasticity/neurogenesis, keys to the development of new experience-dependent memories. The CNS has well-developed mechanisms for rapid removal of glutamate from the synapse because excess glutamatergic activity can lead to excitotoxicity and cell death, and it is part of the ischemic cascade that has been implicated in stroke and in neurodegenerative diseases such as AD and ALS. Memantine (Namenda), an N-methyl-D-aspartate (NMDA) receptor antagonist, is widely prescribed for the treatment of AD. It may seem paradoxical that antagonizing a receptor that is important in learning and long-term potentiation would be of benefit, but it may be able to enhance cognition by selectively inhibiting pathological aspects of glutamatergic activation while preserving the physiological activation of NMDA receptors, thus restoring LTP.

Answer 33

rare neurological disorder characterized by the total or partial loss of the ability to recognize and identify familiar objects and/or people by sight. This occurs without loss of the ability to actually see the person or object. Primary agnosia is associated with bilateral damage to the ventral visual stream, including the lingual and fusiform gyrus. When a person cannot identify familiar people this is called prosopagnosia. two types of visual agnosia are associative and apperceptive.

Answer 34

birth and proliferation of new neurons. most active during pre- and perinatal development. in certain regions of the brain (e.g., dentate gyrus and hippocampus), neurogenesis continues into adulthood and is thought to be a critical basis for the formation of new memories and for experience-dependent neuroplasticity.

Answer 35

changes in neural pathways and synapses due to changes in behavior, environment, or neurochemical processes. Neuroplasticity is critical to normal development of CNS-dependent abilities and is critical to recovery from brain damage. the concept of the brain as a "plastic" organ has replaced earlier conceptualizations that no further structural development or repair was possible after a certain point in development and is an important idea in contemporary advancements in recovery of function, neurorehabilitation, and neural repair. The concept of "experience-dependent neuroplasticity" refers to changes that result from exposure to enriched environments, behavioral practice, or other environmental stimulation.

Answer 36

1. Molecular Layer: Main connections: Dendrites and axons from other layers 2. Small pyramidal layer/External Granular Layer: Main Connections: Cortical-cortical 3. Medium Pyramidal Layer/Internal Granular Layer: Main Connections: Cortical-Cortical 4: Granular Layer/Internal Granular Layer: Main Connections: Receives inputs from thalamus 5. Large Pyramidal Layer/Internal Pyramidal Layer: Main Connections: Sends outputs to subcortical structures (other than thalamus) 6. Polymorphic layer/Multiform Layer. Main Connections:Sends outputs to thalamus.

Answer 37

plane parallel to floor. synonyms = axial and transverse

Answer 38

Diencephalon is part of the forebrain (Prosencephalon) and includes the thalamus, hypothalamus, and supporting structures, such as the epithalamus

Answer 39

cerebral peduncles, midbrain tectum, and midbrain tegmentum The midbrain is relatively short, and most axial sections cut through either the superior colliculi, which are more rostral, or the inferior colliculi, which are more caudal. Sections at these two levels can be distinguished because sections through the superior colliculi also include the oculomotor nuclei and red nuclei, while sections through the inferior colliculi also include the trochlear nuclei and brachium conjunctivum (Decussation of the superior cerebellar peduncles)

Answer 40

Metencephalon: Pons and cerebellum Myelencephalon: Medulla

Answer 41

made up of the supramarginal gyrus at the termination of the sylvian fissure and th e angular gyrus

Answer 42

sometimes called the pyramidal tract bc bc of its triangular shape in the medulla. begins mainly in the primary motor cortex, where neuron cell bodies project via axons down through the cerebral white matter and brainstem to reach the spinal cord. majority (85%) of its fibers cross over to control movement of the opposite side of the body. This pyramidal decussation occurs at the junction between the medulla and the spinal cord. so lesions above the pyramidal decussation produce contralateral weakness with respect to lesion, while lesions below produce ipsilateral weakness.

Answer 43

Motor neurons that project from the cortex down to the spinal cord or brainstem are referred to as upper motor neurons. UMNs form synapses onto the lower motor neurons, which are located in the anterior horns of the central gray matter of the spinal cord or in the brainstem motor nuclei. The axons of the LMNs project of out the CNS via the anterior spinal roots or via the cranial nerves to finally reach muscle cells in the periphery

Answer 44

1. mediate rapid communication between neurons through fast excitatory (excitatory postsynaptic potentials) or inhibitory (inhibitory postsynaptic potentials) electrical events. these occur on timescales of tens of milliseconds. 2. neuromodulation. occurs over slower timescales. includes a broad range of cellular mechanisms involving signaling cascades that regulate synaptic transmission, neuronal growth, and other functions. neuromodulation can either facilitate or inhibit the subsequent signaling properties of the neurons.

Answer 45

tract, fascicle, lemniscus, bundle

Answer 46

white matter pathway that connects structures on the right and left sides of the CNS

Answer 47

afferent: Pathways carrying signals toward a structure efferent: pathways carrying signals away from a structure

Answer 48

nerves controlling the extremities give rise to elaborate mesworks referred to as the brachial plexus (arms) and lumbosacral plexus (legs). there is also more gray matter in these segments, causing the overall cord thickness to be greater here, called cervical enlargement and lumbosacral enlargement.

Answer 49

Cervical 1-8, Thoracic 1-12, Lumbar 1-5, Sacral 1-5

Answer 50

Both controlled by higher centers in the hypothalamus and limbic system as well as by afferent sensory info from the periphery. Sympathetic: "Fight or flight" Arises from T1 to L3 and releases norepinephrine. pupil dilation, bronchodilation, cardiac acceleration, inhibition of digestion, piloerection, stimulation of glucose release, systemic vasoconstriction Parasympathetic: "rest or digest" Arises from the cranial nerves and from S2-4 (craniosacral division) and releases acetylcholine onto end organs pupil constriction, bronchoconstriction, cardiac deceleration, stimulation of digestion, salivation, lacrimation (tears), intestinal vasodilation

Answer 51

a large c-shaped band of white matter (meaning "hard body") connecting both homologous and herologous areas in the two hemispheres consists of the rostrum, genu, body, and splenium

Answer 52

aka interhemispheric fissure/sagittal fissure. separates the two cerebral hemispheres down the midline

Answer 53

gyrus surrounding the corpus callosum, running from the paraterminal gyrus anteriorly to the isthmus posteriorly

Answer 54

runs up to the superior surface that forms an important landmark, since the sulcus immediately in front of it, on the superior surface, is the central sulcus. the central sulcus does not extend onto the medial surface but the region surrounding it is called the paracentral lobule

Answer 55

These structures do not themselves project directly to LMNs. They act by modulating the output of the corticospinal and other descending motor systems. they both receive major inputs from the motor cortex. the cerebellum also receives significant inputs from the brainstem and spinal cord. then in turn, both areas project back to the motor cortex via the thalamus. lesions in the cerebellum lead to disorders in coordination and balance, often referred to as ataxia. lesions in the basal ganglia can result hypokinetic movement disorders, such as Parkinsonism, in which movements are infrequent, slow, and rigid, and hyperkinetic movement disorders such as Huntington's disease, which is characterized by dance-like, involuntary movements.

Answer 56

1. posterior column pathways: convey proprioception, vibration sense, and fine, discriminative touch. sensory neuron axons arrive first to the spinal cord via the dorsal roots and then travel the ipsilateral white matter dorsal columns to to the dorsal column nuclei in the medulla. here they make synapses onto the secondary sensory neurons, which send out axons that cross over to the other side of the medulla. they ascend now on the contralateral side and synapse in the thalamus, and from there neurons project to the primary somatosensory cortex in the postcentral gyrus. 2. anterolateral pathways: convey pain, temperature sense, and crude touch. sensory neuron axons also enter via dorsal roots. however, they make their first synapses immediately in the gray matter of the spinal cord. axons from the secondary sensory neurons cross over to the other side of the spinal cord and ascend in the anterolateral white matter, forming the spinothalamic tract. after synapsing in the thalamus, the pathway again continues to the primary somatosensory cortex.

Answer 57

Important relay center. nearly all pathways that project to the cerebral cortex do so after synapsing in the thalamus. The thalami are grey matter structures. they are located behind the basal ganglia

Answer 58

important region for control of autonomic, neuroendocrine, limbic, and other circuits.

Answer 59

encompasses several small nuclei, including the pineal body, habenula, and parts of the pretectum.

Answer 60

O, O, O, To Touch a Female a Virgin Girl's Vagina, Ah Heaven CN I: Olfactory Nerve. olfaction CN 2: Optic Nerve. vision CN 3: Oculomotor nerve. Extraocular muscles, except those innervated by CN IV and VI; parasympathetics to pupil constrictor and to ciliary muscles of lens for near vision. CN 4: Trochlear Nerve: Superior oblique muscle; causes the eye to move downward and to rotate inward (depression and intorsion) CN 5: Trigeminal Nerve: Sensations of touch, pain, temp, vibration, and joint position for the face, mouth, nasal sinuses, and meninges; muscles of mastication; tensor tympani muscle CN 6: Abducens Nerve: Lateral rectus muscle; causes abduction (outward movement) of the eye. CN 7: Facial Nerve: muscles of facial expression; also stapedius muscle and part of digastric; taste from anterior two-thirds of tongue; sensation from a region near the ear; parasympathetics causing lacrimation and supplying the submandibular and sublingual salivary glands CN 8: Vestibulochoclear nerve: hearing; vestibular sensation CN 9: glossopharyngeal nerve: stylopharyngeus muscle; taste from posterior one-third of tongue; sensation from posterior pharynx, and from a region near the ear; chemo- and baroreceptors of the carotid body; parasympathetics to the parotid gland CN 10: Vagus nerve: Pharyngeal muscles (swallowing); laryngeal muscles (voicebox); parasympathetics to the heart, lungs, and digestive tract up to the splenic flexure; taste from epiglottis and pharynx; sensation from the pharynx, posterior meninges, and a region near the ear; aortic arch and chemo- and baroreceptors CN 11: Spinal Accessory Nerve: Sternomastoid muscle upper part of the trapezius muscle.-- head turning CN 12: Hypoglossal nerve: Intrinsic muscles of the tongue

Answer 61

important region of the brain stem named for the network-like appearance of its fibers in histological sesctions, the reticular formation extends throughout the central portions of the brainstem from the medulla to the midbrain. the more caudal portions of the RF in the medulla and lower pons tend to be involved mainly in motor and autonomic functions. the rostral reticular formation in the upper pons and midbrain plays an important role in regulating level of consciousness, influencing higher areas through modulation of thalamic and cortical activity. lesions of the pontomesencephalic RF can cause lethargy and coma

Answer 62

several structures with this name due to location near the medial edge or fringe of the cerebral cortex. has diverse functions, including regulation of emotions, memory, appetitive drives, and autonomic and neuroendocrine control. includes cortical areas located in the medial and anterior temporal lobes, anterior insula, inferior medial frontal lobes, and cingulate gyri. it also includes deeper structures such as the hippocampal formation and the amygdala, located within the medial temporal lobes, several nuclei of the medial thalamus, hypothalamus, basal ganglia, septal area, and brainstem. these areas are interconnected by a variety of pathways, including the fornix.

Answer 63

a paired, arch-shaped white matter structure that connects the hippocampal formation to the hypothalamus and septal nuclei Lesions here can cause deficits in the consolidation of immediate recall into longer-term memories. can cause behavioral changes and may underlie a number of psychiatric disorders. epileptic seizures most commonly arise from the limbic structures of the medial temporal lobe, resulting in seizures that may begin with emotions such as fear, memory distortions such as deja vu, or olfactory hallucinations.

Answer 64

Inferior parietal lobule in the left hemisphere: difficulty with calculations, right-left confusion, inability to identify fingers by name (finger agnosia), and difficulties with written language.

Answer 65

abnormalities in motor conceptualization, planning, and execution. motor planning appears to be distributed in many different areas of the cortex. so, diffuse lesions of the cortex, or sometimes more focal lesions affecting the frontal or left parietal lobe, can produce apraxia

Answer 66

tactile or visual stimulus is perceived normally when it is presented to one side only, but when it is presented to both sides, the patient neglects the stimulus on the side opposite the lesion. this is a severe abnormality in spatial orientation and awareness. less common in lesions of the dominant parietal lobe, possibly b/c the dominant hemisphere is more specialized in language than it is for visuospatial functions.

Answer 67

Visual association cortex in the parieto-occipital and inferior temporal lobes—can produce prosopagnosia (inability to recognize faces), achromatopsia (inability to recognize colors), palinopsia (persistence or reappearance of an object viewed earlier).

Answer 68

internal carotid arteries- form the anterior blood supply vertebral arteries - join together in a single basilar artery to form the posterior blood supply they join together in an anastomotic ring at the base of the brain- the circle of willis -the ACA and MCA derive their main blood supply from the internal carotid arteries (anterior circulation), while the PCAs derive their main supply from the vertebrobasilar system (posterior circulation). vertebrobasilar system also feeds the main arteries supplying the brainstem and cerebellum.

Answer 69

b supplied almost entirely by the internal jugular veins

Answer 70

the largest foramen, or hole in the brain where the spinal cord meets the medulla, which is called the cervicomedullary junction

Answer 71

from inside out: 1. Pia Mater- very thin, adheres closely to the surface of the brain and follows all the gyri and into the depths of the sulci. it also surrounds the initial portion of each blood vessel as it penetrates the brain surface, forming a perivascular space, and then fuses with the blood vessel wall. 2. Arachnoid Mater - a wispy, "spidery" meningeal layer that adheres to the inner surface of the dura. within this layer, the cerebrospinal fluid percolates over the surface of the brain. 3. Dura Mater: Dura means hard. made of 2 tough, fibrous layers. mater means mother

Answer 72

a flat sheet of dura that is suspended from the roof of the cranium and separates the right and left cerebral hemispheres, running in the interhemispheric fissure.

Answer 73

a tent-like sheet of dura that covers the upper surface of the cerebellum.

Answer 74

from outside to inside: 1. Epidural Space- potential space between the inner surface of the skull and the tightly adherent dura. the middle meningeal artery runs into the epidural space from the external carotid artery and supplies the dura. 2. Subdural Space: potential space between the inner layer of dura and the loosely adherent arachnoid. the bridging veins traverse the subdural space. these veins drain the cerebral hemispheres and pass through the subdural space en route to several large dural venous sinuses. 3. Subarachnoid Space- the cerebrospinal fluid-filled space between the arachnoid and the pia. in addition to cerebral spinal fluid, the major arteries of the brain also travel within the subarachnoid space and tehn send smaller penetrating branches inward through the pia.

Answer 75

specialized vascular structure that lies inside the ventricles and produces cerebrospinal fluid. CSF flows from the lateral ventricles through the foramen of monro in each hemisphere, into the third ventricle, through the Sylvian aqueduct, into the fourth ventricle, out through the foramina of Luschka and Magendie, into the subarachnoid space, and up to the arachnoid granulations to be reabsorbed into the bloodstream.

Answer 76

cavities within the brain that contain cerebrospinal fluid. - 2 lateral ventricles (one inside each hemisphere) - Third ventricle (located within the diencephalon). the walls of the third ventricle are formed by the thalamus and hypothalamus. - fourth ventricle - surrounded by the pons, medulla, and cerebellum.

Answer 77

the subarachnoid space widens in a few areas to form larger CSF collections called cisterns.

Answer 78

the capillary wall endothelial cells in most of the body are separated from each other by clefts, or fenestrations (gaps), allowing relatively free passage of fluids and solute molecules. However, in the brain, capillary endothelial cells are linked by tight junctions forming a blood-brain barrier.

Answer 79

A barrier similar to the blood brain barrier exists between the choroid plexus and the CSF. the capillaries of the choroid plexus are freely permeable, but the choroid epithelial cells form a barrier between the capillaries and the CSF. Lipid-soluble substances, including O2 and CO2, permeate readily across the cell membranes of the BB and B-CSF barriers. However, most other substances must be conveyed in both directions through specialized transport systems, including active transport, facilitated diffusion, ion exchange, and ion channels.

Answer 80

certain specialized brain regions where the BBB is interrupted, allowing the brain to respond to changes in the chemical milieu of the remainder of the body and to secrete modulatory neuropeptides into the bloodstream. Best known among these are the median eminence and the neurohypophysis, which are involved in the regulation and release of pituitary hormones. area postrema: the only paired circumventricular organ, located along the caudal wall of the 4th ventricle in the medulla, AKA (chemotactic trigger zone) is involved in detecting circulating toxins that cause vomitting

Answer 81

AKA: Chemotactic trigger zone the only paired circumventricular organ, located along the caudal wall of the 4th ventricle in the medulla, is involved in detecting circulating toxins that cause vomitting

Answer 82

There are no pain receptors in the brain parenchyma itself. the side of the headache often, but not always, corresponds to the side of pathology. Most are classified as either a vascular headache or a tension headache. vascular headache: used to mean migraine as well as the less common but closely related disorder called cluster headaches. thought to involve inflammatory, autonomic, serotonergic, neuroendocrine, and other influences on blood vessel caliber in the head, leading to headache and other associated symtpoms. In migraine, about 75% of patients have a positive family history, suggesting a genetic basis.

Answer 83

type of vascular headache. about 75% of patients have a positive family history, suggesting a genetic basis. often preceded by an aura or warning symptoms, classically involving visual blurring, shimmering, scintillating distortions, or fortification scotoma- a characteristic region of visual loss bordered by a zigzagging lines resembling the walls of a fort. headache is often unilateral, but if it is always on the same side, an MRI scan is warranted to exclude a vascular malformation or other lesion as a trigger for the headaches. pain is often throbbing and may be exacerbated by light (photophobia), sound (phonophobia), or sudden head movement. nausea and vomitting may occur, and the scalp may be tender to the touch. duration is typically 30 minutes to up to 24 hours, and relief often occurs after sleeping. Treatment is usually quite effective. acute attacks usually respond to NSAIDS, anti-emetics, triptans (serotonin agonists), ergot derivatives, or other medications and to resting in a dark, quiet room. Preventive measures: avoid triggers when possible, and if they are recurring, treatment with prophylactic agents such as beta-blockers, topiramate, valproate, calcium channel blockers such as flunarizine, tricyclic antidepressants, or NSAIDs

Answer 84

migraines can be accompanied by a variety of transient focal neurologic deficits, including sensory phenomena, motor deficits (hemiplegia), visual loss, brainstem findings in basilar migraine, and impaired eye movements in ophthalmoplegic migraine. This is a diagnosis of exclusion and should be accepted only in the setting of recurrent episodes and only after appropriate tests have been done to exclude cerebrovascular disease, epilepsy, or other disorders

Answer 85

less than 1/10 as common as migraine. it occurs about 5x more in males than females. typically, clusters of headaches occur from once to several times per day every day over a few weeks and then vanish for several months. pain is extremely severe, often described as a steady, boring sensation behind one eye, lasting from 30-90 minutes. usually accompanied by unilateral autonomic symptoms such as tearing, eye redness, Horner's syndrome, unilateral flushing, sweating, and nasal congestion. treatment is similar to that for migraine. in addition, inhaled oxygen is often effective in aborting attacks.

Answer 86

AKA Tension-type headaches. steady dull ache, sometimes described as a bandlike sensation. although possibly related to excessive contraction of scalp and neck muscles, the pathophysiological distinction between tension and migraine headaches has been questioned. these include the common type of mild to moderate headache that most individuals experience from time to time, lasting up to a few hours. although these can last continuously every day for years. they are commonly associated with psychological stress, but it is often unclear which is cause and which is effect. Chronic daily headache of this kind is also commonly seen in posttraumatic headache. Treatment includes muscle relaxation techniques, NSAIDs, other analgesics, and tricyclic antidepressants.

Answer 87

Sudden "explosive" onset of severe headache should always be taken seriously and CT scan should be done urgently to see if a subarachnoid hemorrhage has occurred. -headache is also common in cerebral ischemia and infarction and in the post-ictal period following seizures. - Low CSF pressure can occur spontaneously or following a lumbar puncture, resulting in headache that is worse while standing up and better while lying down. - disorders such as neoplasms that can increase intracranial pressure, the headache may be worse when lying down during the night. - headache accompanied by fever or signs of meningeal irritation, such as stiff neck and sensitivity to light, should be evaluated and treated immediately for possible infectious meningitis, since patients with this condition can deteriorate rapidly if untreated.

Answer 88

AKA pseudotumor cerebri- a condition of unknown cause characterized by headache and elevated intracranial pressure with no mass lesion. it is most common in adolescent females, and it is treated with acetazolamide or, when severe, with shunting procedures.

Answer 89

AKA giant cell arteritis- treatable cause of headache. most commonly occurs in elderly individuals. vasculitis affects the temporal arteries and other vessels, including those supplying the eyes. The temporal artery is characteristically enlarged and firm. Diagnosis is made by measurement of the blood erythrocyte sedimentation rate (ESR) and by temporal artery biopsy. Prompt diagnosis and treatment with steroids is essential to prevent possible vision loss.

Answer 90

anything abnormal that occupies volume within the cranial vault functions as a mass. This includes tumor, hemorrhage, abscess, edema, hydrocephalus, and other disorders.

Answer 91

1. Compression and destruction of adjacent regions of the brain can cause neurologic abnormalities. 2. a mass located within the cranial vault can raise the intracranial pressure, which causes certain characteristic signs and symptoms 3. mass lesions can displace nervous system structures so severely that they are shifted from one compartment to another- a situation called herniation.

Answer 92

a descriptive term used for any distortion of normal brain geometry due to a mass lesion. It can be as subtle as a mild flattening, or effacement, of sulci next to a lesion, seen on MRI scan but producing no symptoms.

Answer 93

severe increase in pressure can cause decreased cerebral blood flow and brain ischemia. Cerebral blood flow is defined by the mean arterial pressure minus the intracranial pressure (CPP = MAP -ICP). This means that as intracranial pressure increases, cerebral perfusion pressure decreases.

Answer 94

homeostatic process that regulates and maintains cerebral blood flow constant across a range of blood pressures. it can also compensate for modest reductions in cerebral perfusion pressure. However, large increases in intracranial pressure can exceed the capacity of autoregulation, leading to reduced cerebral blood flow and brain ischemia.

Answer 95

- Headache: often worse in the morning, since the brain edema increases overnight from the effects of gravity on a patient in the reclining position. - Altered mental status: irritability and depressed level of alertness and attention most common. often the most important indicator of elevated intracranial pressure. - Nausea and vomiting: unknown mechanism. vomiting occasionally occurs suddenly and without much nausea. (projectile vomiting) - papilledema-- engorgement and elevation of the optic disc, sometimes accompanied by retinal hemorrhages. b/c the pressure is transmitted through the subarachnoid space to the optic nerve sheath, obstructing axonal transport and venous return in the optic nerve. This takes hours to days to develop and is often not present in the acute setting. transient or permanent damage can occur in association with papilledema, leading to visual blurring or visual loss. - Visual loss: areas of decreased vision most commonly include an increased blind spot or a concentric visual field deficit affecting mainly the peripheral margins of the visual field. - diplopia (double vision)- can occur as a result of downward traction on CN VI, causing unilateral or bilateral abducens nerve palsies. - cushing's triad: Hypertension, bradycardia, and irregular respirations. another classic sign of elevated intracranial pressure. HTN may be a reflex mechanism to maintain cerebral perfusion pressure, bradycardia may be a reflex response to HTN, and irregular respirations are caused by impaired brainstem function.

Answer 96

Double vision

Answer 97

In adults: less than 20 cm H2O or less than 15 mm Hg (torr) intracranial pressure can be measured during lumbar puncture.

Answer 98

occurs when mass effect is severe enough to push intracranial structures from one compartment into another.

Answer 99

AKA tentorial herniation. herniation of the medial temporal lobe, especially the uncus (uncal herniation), inferiorly through the tentorial notch. uncal herniation is heralded by the clinical triad of a "blown" pupil on the ipsilateral side (85% of the time), hemiplegia (can be due to compression at multiple different points- usually contralateral can be ipsilateral if enough to affect the midbrain at the opposite tentorial notch), and coma (due to distortion of the midbrain reticular formation). later, the blown pupil can turn to impaired eye movements.

Answer 100

unilateral mass lesions can cause the cingulate gyrus and other brain structures to herniate under the falx cerebri from one side of the cranium to the other. This usually has no clinical signs but can sometimes occlude one or both anterior cerebral arteries, leading to infarcts in the anterior cerebral artery territory.

Answer 101

Reversible impairment of neurololgic function for a period of minutes to hours following a head injury. Exact mechanism unclear but thought to involve transient diffuse neuronal dysfunction. CT and MRI are normal. Clinical signs: LOC, "seeing stars," followed by headache, dizziness, and occasionally, nausea and vomiting. sometimes accompanied by anterograde and retrograde amnesia for a period of several hours surrounding the injury. Recovery: usually complete. although some patients develop postconcussive syndrome even after a relativvely mild trauma, with headaches, lethargy, mental dullness, and other symptoms lasting up to several months after the accident. Even relatively mild injury can occasionally cause dissection of the carotid or vertebral arteries, resulting in transient ischemic attack or cerebral infarct.

Answer 102

small spots of blood in the white matter. can be caused by severe head trauma.

Answer 103

location: in the tight potential space between the dura and the skull. Usual cause: rupture of the middle meningeal artery due to fracture of the temporal bone by head trauma. Clinical features and radiological appearance: Rapidly expanding hemorrhage under arterial pressure peels the dura away from the inner surface of the skull, forming a lens-shaped biconvex hematoma that often does not spread past the cranial sutures where the dura is tightly apposed to the skull. there is a lucid interval, but then within a few hours the hematoma begins to compress brain tissue, often causing elevated intracranial pressure and ultimately, herniation and death unless treated surgically.

Answer 104

period of no symptoms despite having a hemorrhage

Answer 105

Location: In the potential space between the dura and the loosely adherent arachnoid. Usual cause: rupture of the bridging veins, which are particularly vulnerable to shear injury as they cross from the arachnoid into the dura. clinical features: venous blood dissects relatively easily between the dura and the arachnoid, spreading out over a large area and forming a crescent-shaped hematoma. two types of subdural hematoma- chronic and acute- are distinguished by different clinical features.

Answer 106

often seen in elderly patients, in whom atrophy allows the brain to move more freely within the cranial vault, thus making the bridging veins more susceptible to shear injury. can be seen with minimal or no known cause of trauma. oozing slowly, venous blood collects over a period of weeks to months, allowing the brain to accommodate and therefore causing vague symptoms such as headache, cognitive impairment, and unsteady gait. In addition, focal dysfunction of the underlying cortex may result in focal neurologic deficits and, occasionally, focal seizures.

Answer 107

Requires impact velocity to be quite high for this to occur immediately after an injury. So, usually associated with other serious injuries, such as traumatic subarachnoid hemorrhage and brain contusion. Prognosis is usually worse than with chronic subdural hematoma or even epidural hematoma (due to severity of injury that typically occurs). Radiological appearance: subdural hematomas are typically crescent shaped and spread over a large area. density depends on the age of the blood. acute blood is bright on CT b/c hyperdense. after 1-2 weeks, the clot begins to liquefy and may appear isodense. after 3-4 weeks the hematoma will be completely liquefied and will appear uniformly hypodense. but if there is continued occasional bleeding, there will be a mixed density appearance resulting from liquefied chronic blood mixed wtih clotted hyperdense blood. Treatment: surgical evacuation, except for small to moderate-sized chronic subdural hematomas, which, depending on the severity of symptoms, can be followed clinically b/c some will resolve spontaneously.

Answer 108

blood is hyperdense on CT and thus, shows up bright on CT scan.

Answer 109

seen in mixed density hematomas, where the denser acute blood settles to the bottom, giving a layered appearance.

Answer 110

location: in the CSF-filled space between the arachnoid and the pia, which contains the major blood vessels of the brain. Radiologic appearance: unlike subdural hematoma, blood can be seen on CT to track down into the sulci following the contours of the pia. IMPORTANT to do CT without contrast b/c both subarachnoid blood and contrast material appear white on the scan making it difficult to see a small hemorrhage. If CT is negative, a lumbar puncture may be done. then an angiogram to define the exact location and size of the aneurysm. usual cause: subarachnoid hemorrhage is seen in two clinical settings: non-traumatic (spontaneous) and traumatic. risk factors for aneurysmal rupture (nontraumatic): hypertension, smoking, alcohol, and sudden high blood pressure. Clinical effects: Range from headache to meningeal irritation, to cranial nerve and other focal neurologic deficits, to impaired consciousness, coma, and death. Estimated 25% die in the immediate aftermath and overall mortality is about 50% Treatment: either neurosurgical placement of a clip across the neck of the aneurysm or interventional neuroradiology to place detachable coils within the aneurysm.

Answer 111

usually presents with a sudden catastrophic headache. Described as "worst headache of my life" or as feeling like the head is suddenly about to explode. In 75-80% of cases, spontaneous subarachnoid hemorrhage occurs as a result of an arterial aneurysm in the subarachnoid space. Less often (4-5% of cases), it results from bleeding of an arteriovenous malformation and from other rarer or unknown causes. Risk factors include atherosclerotic disease, congenital anomalies in cerebral blood vessels, polycystic kidney disease, and connective tissue disorders such as Marfan's syndrome.

Answer 112

AKA berry aneurysms, usually arise from arterial branch points near the circle of Willis. they are balloon-like outpouchings of the vessel wall that typically have a neck connected to the parent vessel and a fragile dome that can rupture. Over 85% occur in the anterior circulation (carotid artery and its branches). most common locations, listed in descending order, are the AComm (30%), PComm (25%), MCA (20%). They can also occur in the branches of the posterior circulation (vertebrobasilar system, 15%).

Answer 113

Occurs in about 50% of patients following subarachnoid hemorrhage, with a peak severity about 1 week after hemorrhage. This can lead to cerebral ischemia or infarction. vasospasm is often treated with "triple H" therapy, consisting of induced hypertension, hypervolemia, and hemodilution in the ICU. the latter two are often done acutely at the time of hemorrhage diagnosis to prevent this. hypertension induction waits until after clipping or coiling of aneurysm. Administration of calcium channel blocker nimodipine early after hemorrhage can also improve the outcome, with unclear mechanism. cases of refractory vasospasm can be treated with interventional neuroradiology procedures such as balloon angioplasty and local injection of the vasodilator papaverine.

Answer 114

caused by bleeding into the CSF from damaged blood vessels associated with cerebral contusions and other traumatic injuries, is actually more common than spontaneous subarachnoid hemorrhage. Like spontaneous SAH, it is usually associated with severe headache due to meningeal irritation from blood in the CSF. Deficits are usually related to the presence of other cerebral injuries. Unlike in aneurysmal SAH, vasospasm is not usually seen.

Answer 115

location: within the brain parenchyma in the cerebral hemispheres, brain stem, cerebellum, or spinal cord. usual cause: can be traumatic or non-traumatic

Answer 116

contusions occur in regions where cortical gyri abut the ridges of the bony skull. So, they are most common at the temporal and frontal poles. they are less common at the occipital poles. They occur on the side of the injury (coup injury) as well as on the opposite side of the impact (contrecoup injury) because of rebound of the brain against the skull. Shearing forces can produce areas of bleeding in the white matter as well, including small petechial or larger confluent intraparenchymal hemorrhage. Severe injuries are often accompanied by contusion, SAH and SDH.

Answer 117

causes are broad- including htn, brain tumor, secondary hemorrhage after ischemic infarction, vascular malformations, blood coagulation abnormalities, infections, vessel fragility caused by deposition of amyloid protein in the blood vessel wall (amyloid angiopathy), vasculitis, mycotic (infectious) aneurysms in the setting of endocarditis, etc. HTN hemorrhage is most common and tends to involve small, penetrating blood vessels. Most common locations for HTN hemorrhage is basal ganglia (usually putamen), thalamus, cerebellum, and pons. can have ventricular involvement: intraventricular extension of an intraparenchymal hemorrhage or intraventricular hemorrhage. Unlike aneurysmal hemorrhage, the rebleeding rate for HTN hemorrhage is low, although the hematoma often continues to enlarge, causing worsening clinical status for several hours after onset. Edema also gradually develops which can worsen clinical picture and peaks about 3 days after onset. Lobar hemorrhage: bleeding involving the occipital, parietal, temporal or frontal lobe. Most common cause is probably amyloid (congophilic) angiopathy. Hemorrhages tend to be recurrent or multiple, and tehy are often more superficial in location. Transient symptoms resembling TIA or seizures can occur in amyloid angiopathy for weeks or months preceding hemorrhage. arteriovenous malformations and cavernomas also have a high likelihood of causing hemorrhage. AVMs are congenital abnormalities in which there are abnormal direct connections between arteries and veins, often forming a tangle of abnormal blood vessels visible as flow voids on MRI, but best seen on conventional angiography. Treatment for AVM can include neurosurgical removal, intravascular embolization, and stereotactic radiosurgery. Cavernomas are abnormally dilated vascular cavities lined by only one layer of vascular endothelium. they are not visible on conventional angiography, but with the advent of MRI the diagnosis of cavernous malformations has increased dramatically. characteristic MRI appearance, with a central 1-2cm core of increased signal on T1 or T2, surrounded by a dark rim on T2-weighted sequences b/c of the presence of hemosiderin. A familial autosomal dominant form of this disorder exists and can have multiple. Patients often present with seizures.

Answer 118

head trauma can cause hemorrhage in the inner ear, called hemotympanum; hemorrhage in subcutaneous tissues, resulting in Battle's isgn; or "raccoon eyes". Scalp hemorrhage can cause profuse bleeding. hemorrhage in the loose space between the external periosteum and galea aponeurotica can produce a "goose egg" or subgaleal hemorrhage.

Answer 119

1. excess CSF production---quite rare. seen in certain tumors, such as choroid plexus papilloma. 2. obstruction of flow at any point in the ventricles or subarachnoid space--- can be caused by blockage of ventricles by tumors, intraparenchymal hemorrhage, other masses, and congenital malformations. this can also occur due to blocks in the subarachnoid space as a result of debris, or adhesions from prior hemorrhage, infection, or inflammation. 3. decrease in reabsorption via the arachnoid granulations. - occurs when arachnoid granulations are damaged or clogged. hard to clinically really distinguish from obstruction.

Answer 120

1. Communicating Hydrocephalus- caused by impaired CSF reabsorption in the arachnoid granulations, obstruction of flow in the subarachnoid space, or (rarely) by excess CSF production. 2. Noncommunicating hydrocephalus- caused by obstruction of flow within the ventricular system.

Answer 121

similar to those of any other cause of elevated intracranial pressure and can be acute or chronic, depending on how quickly the hydrocephalus develops. Headache, nausea, vomiting, cognitive impairment, decreased LOC, papilledema, decreased vision, and 6th nerve palsies. ventricular dilation may also compress descending white matter pathways from the frontal lobes, leading to frontal lobe-like abnormalities including an unsteady magnetic gait (feet barely leaving the floor) and incontinence. in neonatal hydrocephalus, when the cranial sutures have not yet fused, the skull expands to reduce elevated intracranial pressure, resulting in increased head circumference. a bulging anterior fontanelle is also an important sign of elevated intracranial pressure in infants.

Answer 122

6th-nerve palsy seen in mild and slowly developing cases. causes incomplete or slow abduction of the eye in the horizontal direction. Can affect one or both eyes. in more severe hydrocephalus, inward deviation of one or both eyes may be present at rest. or dilation of the suprapineal recess of the posterior third ventricle can push downward onto the collicular plate of the midbrain, producing Parinaud's syndrome. This causes limited vertical gaze, especially in the upward direction.

Answer 123

external ventricular drain (AKA ventriculostomy) drains fluid from the lateral ventricles into a bag outside the head. Ventriculoperitoneal shunt: more permanent treatment, in which the shunt tubing passes from the lateral ventricle out of the skull and is then tunneled under the skin to drain into the peritoneal cavity of the abdomen. Endoscopic neurosurgery: minimally invasive. a narrow tube (cannula) is introduced into the cranium or spine through a small incision. tools can then be passed through the cannula to repair obstructive hydrocephalus and intraventricular mass lesions.

Answer 124

a condition sometimes seen in the elderly, characterized by chronically dilated ventricles. Present with clinical triad of gait difficulties, urinary incontinence, and mental decline. Measurements of CSF pressure are usually not elevated; however, some studies have wshown pressure elevations to occur only intermittently. Exact mechanism unknown, but NPH is thought to be a form of communicating hydrocephalus with impaired CSF reabsorption at the arachnoid villi. Some patients improve dramatically (particularly with gait) after large-volume CSF removal by lumbar puncture or in a more permanent manner following shunting.

Answer 125

a descriptive term and not itself responsible for any pathology. it refers to excess CSF in a region where brain tissue was lost as a result of stroke, surgery, atrophy, trauma, or other insult.

Answer 126

1. Primary CNS tumors- arise from abnormal proliferation of cells originating in the nervous system 2. metastatic tumors- arise from neoplasms originating elsewhere in the body that spread to the brain. 5-10 times more common than all primary CNS tumors combined.

Answer 127

In adults 70% of brain tumors are supratentorial and 30% infratentorial. In chidlren, the opposite. 70% located in the posterior fossa and 30% supratentorially. Most common in adults: gliomas and meningiomas, followed by pituitary adenoma, schwannoma, and lymphoma. In kids, mos common are astrocytoma, medulloblastoma, followed by ependymoma. B/c they are often in the posterior fossa, they tend to cause hydrocephalus through compression and obstruction of the fourth ventricle or aqueduct of Sylvius.

Answer 128

depends on location, size, and rate of growth. Headache and other signs of elevated intracranial pressure are common at presentation. some pay present with seizures or with focal symptoms and signs, depending on the location of the tumor. low-grade gliomas and meningiomas most commonly present with seizures.

Answer 129

33% of total brain tumors. subdivided into several types. Glial tumors arising from astrocytes are called astrocytomas. Astrocytomas classified by WHO on grading system, with most benign is grade I and the most malignant is grade IV. -Grade IV is glioblastoma multiforme, which are actually relatively common and usually lead to death in 1-2 years despite maximal resection, radiation, and chemotherapy.

Answer 130

33% of total brain tumors. arise from the arachnoid villus cells and occur over the lateral convexities, in the falx, and along the basal regions of the cranium. Quite slow growing. possible association with breast cancer in females, but with uncertain pathophysiological links. Treated by local excision.

Answer 131

12% of brain tumors. can cause endocrine disturbances or compress the optic chiasm, usually resulting in bitemporal visual field defect. Treatment with dopaminergic agonists will often inhibit function and shrink the size of prolactinomas, the most common type of pituitary adenoma. if unsuccessful, transsphenoidal resection is performed.

Answer 132

can occur with numerous tumor types. 3 most common are lung or breast carcinoma and melanoma.

Answer 133

relatively rare neurologic disorders caused by remote effects of cancer in the body, leading to an abnormal autoimmune response. Examples include limbic or brainstem encephalitis, cerebellar Purkinje cell loss, spinal cord anterior horn cell loss, neuropathy, impaired neuromuscular transmission, and opsoclonus myoclonus, which is characterized by irregular jerking movements of the eyes and limbs. Tumors that most often cause paraneoplastic syndromes include small cell lung carcinoma, breast cancer, and ovarian cancer. Testing for specific antibodies that cross-react with tumor cells may be helpful in diagnosis.

Answer 134

important bacterial infections caused by cocci and bacilli include bacterial meningitis, brain abscess, and epidural abscess. Bacteria most often gain access to the nervous system through the bloodstream, and they frequently originate from an infection elsewhere in the body, such as the respiratory tract or heart valves (endocarditis). Infections can also spread by direct extension from the oronasal passages. trauma or surgery can also introduce bacteria into the nervous system from the skin. Infectious meningitis: infection of the CSF in the subarachnoid space. can be caused by bacteria, viruses, fungi, or parasites. It is usually heralded by marked signs and symptoms of meningeal irritation, or meningismus. common features include headache, lethargy, sensitivity to light and noise, fever, nuchal rigidity (neck muscles contract involuntarily resulting in resistance to active or passive neck flexion and neck pain). --onset depends on cause and can be gradual over weeks to months (fungal or parasitic infections) or may progress rapidly, within hours in the case of many bacterial infections. DX with clinical evaluation and lumbar puncture. CT first b/c removal of CSF in presence of a mass lesion can occasionally precipitate herniation. Antibacterial therapy should be immediately administered as this can be rapidly fatal if left untreated.

Answer 135

CSF typically has a high white blood cell count (100-5000) with a polymorphonuclear predominance, high protein, and low glucose. underlying pathogen and appropriate treatment varies with age. see 161 of blumenfeld. regardless, treatment should be immediate. Complications can include seizures, cranial neuropathies, cerebral edema, hydrocephalus, herniation, cerebral infarcts, and death.

Answer 136

important bacterial infection of the nervous system. presents as an expanding intracranial mass lesion, much like a brain tumor, but often with a more rapid course. in adidtion to bacteria, parasites can also cause brain abscess. presenting features commonly include headache, lethargy, fever, nuchal rigidity, nausea, vomiting, seizures, and focal signs determined by the location of the abscess. fever is absent in about 40% of cases, and WBC not elevated in about 20, which complicates diagnosis. small abscess may be treated with antibiotics and observation. larger with concern for catastrophic rupture, mass effect, or progressive deterioration should be treated with stereotactic needle aspiration or surgical removal and antibiotics.

Answer 137

two most important are neurosyphilis and Lyme disease. Neurosyphilis was common in pre-penicillin era and has had a resurgence in recent years, possibly related to HIV. diagnosis is based on blood tests for trponemes, together with CSF showing lymphocyte-predominant meningitis. Lyme Disease is caused by the spirochete carried by Ixodes species of deer tick, which are endemic to certain areas of the US, Europe, and Australia. Named after the town Lyme, Connecticut, where the disorder was first described. Primary infection is often heralded by a characteristic raised rash, called erythema chronicum migrans, which gradually shifts location and enlarges over days to weeks. Neurologic manifestations can sometimes occur and are delayed by several weeks. they include a lympocyte-predominant meningitis or mild meningoencephalitis, characterized by meningeal signs and emotional changes, with impaired memory and concentration. other features can include cranial neuropathies, peripheral neuropathies, and rarely, spinal cord involvement. Non-neurologic manifestations include arthritis and cardiac conduction abnormalities. Diagnosed by typical clinical features, lumbar puncture, and serological testing. untreated cases can eventually show white matter abnormalities on MRI scan. treated with intravenous ceftriaxone when there is neurological involvement.

Answer 138

sometimes called aseptic meningitis (along with other types of lymphocyte-predominant meningitis such as CNS Lyme, neurosyphilis, tuberculous meningitis) to distinguish from bacterial meningitis. less fulminant than bacterial meningitis and recovery usually occurs spontaneously within 1-2 weeks. Presents with headache, fever, lethargy, nuchal rigidity, and other signs of meningeal irritation. Common causes include enteroviruses such as echovirus, coxsackievirus, and mumps virus. Often the causative agent is not identified. often there is no specific treatment except for herpes and HIV. CSF shows an elevated WBC with a lymphocytic predominance, normal or mildly elevated protein, and normal glucose.

Answer 139

viral infections involving the brain parenchyma. clinical manifestations are usually quite severe compared to viral meningitis. meninges are often also involved, resulting in meningoencephalitis. Herpes Simplex Virus is the most common cause (usually type 1). HSV has a tropism for limbic cortex. Pts often present with bizarre psychotic behavior, confusion, lethargy, headache, fever, meningeal signs, and seizures. focal signs can be present as well. Causes necrosis of unilateral or bilateral temporal and frontal structures often visible on MRI. Untreated, it progresses within days to coma and death. Immediate treatment with acyclovir is indicated. Other causes exist, but unfortunately none have a specific treatment. Measles is associated with a delayed, slowly progressive fatal encephalitis called subacute sclerosing panencephalitis. incidence has dropeed markedly since the introduction of the measles vaccine. Herpes zoster, or shingles, is an infection caused by the same virus as chickenpox. the primary symptoms is a painful rash conforming to nerve root distributions.

Answer 140

viral infections of the nervous system are a common cause of transverse myelitis, inflammation of both sides of one section of the spinal cord. causes include enteroviruses such as coxsackie and poliomyelitis, varicella-zoster virus, HIV, or less commonly, Epstein-Barr virus, cytomegalovirus, herpes simplex, rabies, or Japanese B virus.

Answer 141

can increase risk for viral, bacterial, fungal, and parasitic infections of the nervous system. HIV itself can cause an aseptic meningitis at the time of seroconversion. sometimes associated with cranial neuropathies, especially involving the facial nerve. HIV-associated neurocognitive disorder (HAND) is a common neurologic manifestation of HIV, with increased frequency late in the course of illness. treatment with anti-retroviral agents can cause some improvement in AIDS-related dementia. can also see encephalitis caused by herpes simplex virus, varicella-zoster virus, or cytomegalovirus. Progressive multifocal leukoencephalopathy can occur in patients with AIDS or other immunodeficiency states. and results in gradual demyelination of the brain, usually leading to death within 3-6 months. bacterial infections can include tuberculous meningitis and neurosyphilis. Fungal infections may include cryptococcal meningitis - sign is chronic headache. and it is diagnosed by lumbar puncture. Common parasitic infection is toxoplasmosis. caused by reactivation of infection with the parasite Toxoplasma gondii. Initial exposure is from cysts in cat feces or undercooked meat, and is usually asymptomatic. when this spreads to CNS it causes brain abscesses visible on MRI as ring-enhancing lesions: a nonenhancing center (dark on T1) surrounded by a ring of enhancement after administration of gadolinium. presenting features can include seizures, headache, fever, lymphocytic predominant meningitis, and focal signs, depending on the location of the lesions. those with AIDS are at risk for primary central nervous system lymphoma. This B cell lymphoma can appear radiologically similar to toxoplasmosis. it is the 2nd most common cause of intracranial mass lesions in HIV. diagnosed by brain biopsy. treatment with steroids and radiation therapy may be of some benefit, although the prognosis is much worse than for primary CNS lymphoma without HIV.

Answer 142

fungal infection of the CNS that occurs mainly in diabetics in the rhinocerebral form and also involves teh orbital apex. causes opthalmoplegia, facial numbness, visual loss, and facial weakness, with a typical violet coloration of the tips of the eyelids. It is treated with amphotericin B. Steroids can exacerbate fungal infections and should be avoided when a fungal infection is suspected. most fungal infections can only be diagnosed by biopsy, which should be pursued aggressively because early treatment is essential.

Answer 143

Protein-based infectious agent called the prion has been identified in certain neurologic disorders. They are unique in their ability to transmit illnesses from one animal to another, despite the fact that they apparently do not contain DNA or RNA. Pathologically, diffuse degeneration of the brain and spinal cord occurs, with multiple vacuoles resulting in a spongiform appearance. Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker disease, kuru, and fatal familial insomnia. all relatively rare, but CJD the most common of them, with an incidence of approximately 1 new case per million per year.

Answer 144

a prion disease. features include rapidly progressive dementia, an exaggerated startle response, myoclonus, visual distortions or hallucinations, and ataxia. EEG often shows periodic sharp wave complexes, especially late in the course of the illness. CSF usually shows increased 14-3-3 protein. MRI may show a characteristic increased signal in the basal ganglia and cortical ribbon on diffusion weighted imaging (DWI). No treatment. Death usually occurs within 6-12 months.

Answer 145

Provides direct access to the subarachnoid space of the lumbar cistern. Used to sample CSF, measure CSF pressure, to remove CSF in cases of suspected NPH, and occasionally to introduce drugs (antibiotics or cancer chemotherapy) or radiological contrast material (in myelography) into the CSF. --Prior to LP, patietn should be evaluated for evidence of elevated intracranial pressure and risk of herniation. usually safest practice is to perform a CT scan. Other risks are cases of impaired coagulation b/c of the risk of iatrogenic spinal epidural hematoma, which can compress the cauda equina. Can be done sitting or lying down. Lying down position is more reliable for measuring pressure b/c in sitting position, the entire column of CSF in the spinal canal adds to the pressure measured in the lumbar cistern. Normal CSF pressure in adults is less than 20 cm HTO. Red blood cells are usually not present in the CSF and if they are, this can indicate subarachnoid hemorrhage., hemorrhagic herpes encephalitis, or they may simply have been introduced by damage to blood vessels caused by the spinal needle at the time of lumbar puncture, referred to as a traumatic tap. a traumatic tap is usually characterized by RBC decreasing in number from the first to last tubes of CSF-- but not in SAH. yellow tent can also be a sign of SAH when the blood is centrifuged- as this is not present with blood from traumatic tap (xanthocromic - term for the yellow appearance)- shows blood is older if SAH was at least 2+ hours ago. Traumatic Tap also messes up glucose and white blood count- but ways to estimate what it should be, taking this into account. LP can be used to diagnose infection or hemorrhage, diagnosing neoplastic or carcinomatous miningitis, and it can be useful for immunologic testing such as detection of oligoclonal bands in suspected MS.

Answer 146

- Posterior Column-medial lemniscal pathway: conveys proprioception, vibration sense, and fine, discriminative touch. - Anterolateral pathway: include the spinothalamic tract and other associated tracts that convey pain, temperature sense, and crude touch.

Answer 147

a peripheral region innervated by sensory fibers from a single nerve root level

Answer 148

1. Lateral corticospinal tract. Motor tract. pyramidal decussation (cervico-medullary junction) 2. Posterior column-medial lemniscal pathway. Sensory (vibration, joint position, fine touch). Decussation: internal arcuate fibers (lower medulla) 3. Anterolateral Pathways. sensory (pain, temperature, crude touch). Decussation: Anterior commissure (spinal cord).

Answer 149

thalamus is divided into a medial nucleus group, lateral nuclear group, and anterior nuclear group by a Y-shaped white matter structure called the internal medullary lamina. Nuclei located within the internal medullary lamina itself are called the intralaminar nuclei. The midline thalamic nuclei are an additional thin collection of nuclei lying adjacent to the third ventricle, several of which are continuous with an functionally very similar to the intralaminar nuclei. Finally, the thalamic reticular nucleus forms an extensive but thin sheet enveloping the lateral aspect of the thalamus. 3 main types of nuclei in the thalamus: relay nuclei, intralaminar nuclei, reticular nucleus 1. Relay nuclei: most of thalamus is made up of relay nuclei, which receive inputs from numerous pathways and then project to the cortex. in addition, relay nuclei receive massive reciprocal connections back from the cortex. Projections of relay nuclei to the cortex may be fairly localized to specific cortical regions or more diffuse. All sensory modalities, except olfaction, have specific relays in the lateral thalamus en route to their primary cortical areas. - -visual information is relayed in the LGN - -somatosensory pathways from spinal cord and cranial nerves relay in the ventral posterior lateral (VPL) and ventral posterior medial (VPM) nuclei, respectively. - auditory information is relayed in the medial geniculate nucleus (MGN). Important widely projecting (nonspecific) thalamic relay nuclei: those with widespread cortical projections. --Visual and other sensory inputs to the pulvinar are relayed to large regions of the parietal, temporal, and occipital association cortex involved in behavioral orientation toward relevant stimuli. The pulvinar ("couch" or "cushion" in Latin) is a large, pillow-shaped nucleus that occupies most of the posterior thalamus. 2. Intralaminar nuclei: lie within the internal medullary lamina. they receive inputs from numerous pathways and have reciprocal connections with the cortex. Their main inputs and outputs are from the basal ganglia. 3. Reticular Nucleus. the only nucleus of the thalamus that does not project to the cortex. instead, it receives inputs mainly from the other thalamic nuclei and the cortex and then projects back to the thalamus. The reticular nucleus consists of an almost pure population of inhibitory GABAergic neurons. This composition, together with its connections with the entire thalamus, make it well suited to regulate thalamic activity. ir also has input from the brainstem reticular activating system of alertness and attention.

Answer 150

lesions of the somatosensory pathways can cause abnormal positive sensory phenomena called parathesias. - lesions of posterior column-medial lemniscal pathways: can cause tingling, numb sensation; a feeling of a tight, bandlike sensation around the trunk or limbs; or a sensation similar to gauze on the fingers when trying to palpate objects. - lesions of the anterolateral pathways: can cause sharp, burning, or searing pain. - lesions of the parietal lobe or primary sensory cortex may cause contralateral numb tingling, although pain can also be prominent. - lesions of thalamus: can cause severe contralateral pain, called Dejerine-Roussy syndrome. - lesions of the cervical spine may be accompanied by Lhermitte's sign, an electricity-like sensation running down the back and into the extremities upon neck flexion. - lesions of the nerve roots: often cause radicular pain that radiates down the limb in a dermatomal distribution. it is accompanied by numbness and tingling, and is provoked by movements that stretch the nerve root. - peripheral nerve lesions: often cause pain, numbness, and tingling in the sensory distribution of the nerve.

Answer 151

- dysesthesia- unpleasant, abnormal sensation - allodynia- painful sensations provoked by normal nonpainful stimuli such as light touch hyperpathia or hyperalgesia - enhanced pain to normally painful stimuli. -hypesthesia - decreased sensation, but it may be misinterpreted and is thus best avoided (b/c unclear if it means hyper or hypo to many).

Answer 152

causes deficit on the contralateral side. discriminative touch and joint position sense are often most severely affected, but all modalities may be involved.

Answer 153

the lesion involves anterolateral pathways and the spinal trigeminal nucleus on the same side. it causes loss of pain and temperature sensation in the body opposite the lesion, and loss of pain and temperature sensation in the face on the same side as the lesion.

Answer 154

lesion involves the medial lemniscus, causing contralateral loss of vibration and joint position sense.

Answer 155

region of the retina with the highest visual acuity

Answer 156

oval region approximately 3 by 5 mm that surrounds the fovea and also has relatively high visual acuity.

Answer 157

region where the axons leaving the retina gather to form the optic nerve.

Answer 158

- rods: more numerous than cones by 20:1. but have relatively poor spatial and temporal resolution of visual stimuli, and they do not detect colors. help us with low-level lighting conditions. - Cones: less numerous overall, but they are much more highly represented in the fovea, where visual acuity is highest. Cones have relatively high spatial and temporal resolution, and they detect colors.

Answer 159

- Scotoma- a circumscribed region of visual loss - homonymous defect- a visual field defect in the same region for both eyes - refractive error: Indistinct vision improved by corrective lenses - Photopsias: bright, unformed flashes, streaks, or balls of light - Phosphenes: Photopsias produced by retinal shear or optic nerve disease - Entopic Phenomena: Seeing structures in one's own eye - Illusions: distortion or misinterpretation of visual perception - Hallucination: Perception of something that is not present

Answer 160

these include seeing people, animals, or complex scenes. they arise from the inferior temporo-occipital visual association cortex. Common causes include toxic or metabolic disturbances (especially hallucinogens, anticholinergics, and cyclosporin), withdrawal from alcohol or sedatives, focal seizures, complex migraine, neurodegenerative disorders such as CJD or LBD, narcolepsy, midbrain ischemia (peduncular hallucinosis), or psychiatric disorders (although in psych, visual hallucinations are less common than auditory and visual hallucinations usually occur with accompanying sound).

Answer 161

visual hallucinations that occur in elderly as a result of impaired vision.

Answer 162

damage to the optic chiasm typically causes a bitemporal hemianopia

Answer 163

Lesions of the MCA inferior division: can interrupt the lower optic radiations as they loop through the temporal lobe (Meyers loop). These lesions can cause contralateral superior quadrantanopia or pie in the sky visual defect. Lesions of the MCA superior division: can interrupt the upper portions of the optic radiations as they pass through the parietal lobe. This can cause a contralateral inferior quadrantanopia or pie on the floor visual defect Lesions of the entire optic radiation cause a contralateral homonymous hemianopia (one whole half of visual field of both eyes).

Answer 164

Lesions to the upper Bank of the calcarine fissure cause a contralateral inferior quadrantanopia Lesions to the lower bank cause a contralateral superior quadrantanopia Damage to the entire primary visual cortex causes a contralateral homonymous hemianopia

Answer 165

- What stream- Inferior occipitotemporal visual association cortex is supplied by the PCA - where stream- lateral parieto-occipital visual association cortex lies in the MCA-PCA watershed territory.

Answer 166

And inflammatory demyelinating disorder of the optic nerve that is epidemiologically and pathophysiologically related to MS. Like MS, mean age of onset is in the 30s, onset after age 45 is rare, and there is a two to one female to male ratio. About 50% or more of patients with an isolated episode of optic neuritis will eventually develop MS. Clinical features at onset include eye pain, especially with eye movement, and monocular visual problems. The visual impairment typically includes a monocular central scotoma, which is visual loss in the center of the visual field. Additional features include decreased visual acuity, and impaired color vision. In severe cases, complete loss of vision in one eye may occur. Onset of optic neuritis can be acute or a slowly progressive over several days to weeks. Recovery usually begins within two weeks, and near complete recovery is commonly seen within 6 to 8 weeks and sometimes over a few months. There is often some residual visual loss which can be severe, especially after repeated bouts. A second episode occurs in about 1/3 of cases.

Answer 167

On the dorsal surface of the midbrain are two pairs of bumps called the superior colliculi and inferior colliculi. Together these form the tectum (meaning roof) of the midbrain.

Answer 168

The cerebral peduncles formed the ventral surface of the midbrain

Answer 169

Some say marry money but my brother says big brains matter more.

Answer 170

Means a spinning sensation of movement.

Answer 171

The most common facial nerve disorder. Where all divisions of the facial nerve are impaired within a few hours or days and then gradually recover. The cause is unknown, although viral or inflammatory mechanisms have been suggested. The most striking feature is unilateral facial weakness of the lower motor neuron type, which can be mild but is often severe.

Answer 172

In this condition, patients experience recurrent episodes of brief severe pain lasting from seconds to a few minutes, most often in the distribution of V2 or V3. Attacks usually begin after age 35. Painful episodes are often provoked by chewing shaving or touching a specific trigger point on the face. Facial sensation is normal. The cause is usually unknown. It can also be seen in MS possibly caused by demyelination in the trigeminal nerve entry zone of the brainstem.

Answer 173

Olfactory loss due to issue with cranial nerve one. Unilateral olfactory loss is rarely detected by the patient because olfaction in the contralateral nostril can compensate. Patients may complain of decreased taste because of the important contribution of olfaction to the perception of flavor. Can be caused by head trauma, which damages the olfactory nerves as they penetrate the cribriform plate of the ethmoid. Can be caused by viral infections that damage the olfactory neuroepithelium. Obstruction of the nasal passages can impair olfaction. Bilateral anosmia is also common in patients with certain neurodegenerative conditions such as Parkinson's disease and Alzheimer's disease.

Answer 174

Sensation is provided by the trigeminal nerve (CN V), while movement of the muscles of facial expression is provided by the facial nerve (CN VII)

Answer 175

The anterior two-thirds and posterior one-third of the tongue are derived from different branchial arches and therefore have different innervation. For the anterior two-thirds of the tongue, taste is provided by the facial nerve (CN VII), which general somatic sensation is provided by the trigeminal nerve (V3 mandibular division). For the posterior one-third, both taste and general somatic sensation are provided by the glossopharyngeal nerve (CN IX). Taste for the epiglottis and posterior pharynx is provided by the vagus nerve (CN X). General sensation for the teeth, nasal sinuses, and inside of the mouth, above the pharynx and above the posterior one-third of the tongue, is provided by the trigeminal nerve (CN V)

Answer 176

For the pharyngeal gag reflex, general somatic sensation is provided by the glossopharyngeal and the vagus nerves (CN IX and X), but branchial motor innervation is provided mostly by the vagus. For the larynx, the vagus provides both sensory and motor innervation. General somatic sensation for organs below the level of the larynx is provided by the spinal nerves.

Answer 177

Sensation from the supratentorial dura mater is carried by the trigeminal nerve (CN V), while the dura of the posterior cranial fossa is supplied by the vagus (CN X) and by the upper cervical nerve roots.

Answer 178

The lower portions of the face (CNII), soft palate (CN V, X), upper trapezius muscle (CN XI), and tongue (CN XII) receive mainly contralateral input, so they show weakness on the side opposite to the cortical or corticobulbar lesions. Other cranial nerves do not typically show unilateral deficits with unilateral UMN lesions, although, unilateral cortical or corticobulbar tract lesions can cause nonlateralized dysfunction in articulation (dysarthria) and swallowing (dysphagia)

Answer 179

Drooping of the upper eyelid.

Answer 180

rapid eye movements reaching velocities of up to 700 degree per second. They function to bring targets of interest into the field of view. Vision is transiently suppressed during saccadic eye movements. Saccades are the only type of eye movement that can easily be performed voluntarily, although they can be elicited by reflexes as well.

Answer 181

do not occur under voluntary control, and they reach velocities of only 100 degree per second. they allow stable viewing of moving objects.

Answer 182

maintain fused fixation by both eyes as targets move toward or away from the viewer. the velocity is about 20 degrees per second.

Answer 183

include optokinetic nystagmus and the vestibulo-ocular reflex.

Answer 184

Nystagmus is a rhythmic form of reflex eye movements composed of slow eye movements in one direction interrupted by fast, saccade-like eye movements in the opposite direction.

Answer 185

Brainstem centers controlling vertical eye movements are located in the rostral midbrain reticular formation and pretectal areas. The ventral portion of this region is thought to mediate downgaze, while the more dorsal region mediates upgaze. One important nucleus that is thought to mediate downgaze is the rostral interstitial nucleus of the MLF. PSP is associated with impaired vertical eye movements and midbrain atrophy. In addition, in locked in syndrome large ponteen lesions can disrupt the bilateral corticospinal tracts and abducens nuclei, eliminating body movements and horizontal eye movements.

Answer 186

a constellation of eye abnormalities usually seen with lesionss compressing the dorsal midbrain and pretectal area. The four components are: 1. impairment of vertical gaze, especially upgaze. This may be due to compression of the dorsal part of the vertical gaze center 2. large, irregular pupils that do not react to light but sometimes may react to near- far accommodation. This light- near dissociation may occur as a result of disruption of optic tract fibers traveling to the Edinger-Westphal nuclei via dorsal pathways including the posterior commissure, well fibers descending from the visual cortex take a different route and are relatively spared. 3. eyelid abnormalities ranging from bilateral lid retraction (collier’s sign) or “tucking” to bilateral pstosis. 4. Impaired convergence and sometimes convergence-retraction nystagmus, in which the eyes rhythmically converge and retract in the orbits, especially an attempted upgaze. Common causes of this syndrome are pineal region tumors and hydrocephalus, as well as multiple sclerosis or vascular disease of the midbrain and pretectal area.

Answer 187

Frontal eye fields: Thought to lie more posteriorly, at the junction between the superior frontal sulcus and the precentral sulcus, in brodman area six. The frontal eye fields generate saccades in the contralateral direction via connections to the contralateral PPRF. Parieto-occipito-temporal cortex (control of eye movements): Primarily responsible for smooth pursuit movements in the ipsilateral direction, via connections with the vestibular nuclei, cerebellum, and PPRF. The basal ganglia also plays a role in modulatory control of eye movements, and characteristic disorders of eye movements can be seen in basal ganglia dysfunction.

Answer 188

Lesions of the cerebral hemispheres normally impair eye movements in the contralateral direction, often resulting in a gaze preference toward the side of the lesion. This gaze preference is typically accompanied by weakness contralateral to the lesion if the corticospinal pathways are involved, so that the eyes look away from the side of the weakness. This is termed right- way eyes. Certain clinical situations can cause the eyes to look toward the side of the weakness. This condition is called wrong-way eyes. Causes of wrong- way eyes include seizure activity in the cortex, which can drive the eyes in the contralateral direction because of activation of the frontal eye fields, while also causing abnormal or decreased movements of the contralateral side of the body because of involvement of motor association cortex and other structures. For unclear reasons, large lesions such as the thalamic hemorrhage can disrupt the corticospinal pathways of the internal capsule, causing contralateral weakness, yet may also cause the eyes to deviate toward the side of the weakness. Lesions in the thalamic region causing wrong- way eyes are usually accompanied by deep coma. Finally, lesions of the pontine basis and tegmentum can cause wrong- way eyes because disruption of the corticospinal fibers causes contralateral hemiplegia, while involvement of the abducens nucleus or PPRF causes ipsilateral gaze weakness

Answer 189

1. Cranial nerve nuclei and related structures 2. Long tracts 3. cerebellar circuitry 4. Reticular formation and related structures comes

Answer 190

patients who have absent motor function but maintain intact sensation and cognition. usual cause is an infarct in the ventral pons affecting the bilateral corticospinal and corticobulbar tracts. this condition can mimic coma- but should be carefully distinguished. these patients have spared reticular activating systems and sensory pathways. they are fully aware and able to feel, hear, and understand everything in their environment. . they often have spared eye opening and vertical eye movements. they can thus communicate using eye movements. special computer interfaces based on eye movements have been developed for patents with locked-in syndrome.

Answer 191

lesions of the cerebellar circuitry produce a characteristic uncoordinated wavering movement abnormality. ataxia typically occurs ipsilateral to the side of the lesion because cerebellar circuits tend to decussate twice before reaching lower motor neurons.

Answer 192

connected by 3 large white matter pathways called the cerebellar peduncles. The superior cerebellar peduncle contains mainly cerebellar outputs. the decussation of the superior cerebellar peduncles occurs in the midbrain at the level of the inferior colliculi. Cerebellar output fibers then continue rostrally to reach the red nucleus of the midbrain at the level of the superior colliculi. Other fibers continue rostrally to ultimately influence primary motor cortex and premotor cortex via relays in the ventrolateral nucleus of the thalamus. The middle cerebellar peduncle is the larges of the cerebellar peduncles. It contains massive inputs to the cerebellum arising from the pontine nuclei scattered through the basis pontis. The pontine nuclei, in turn, receive inputs from the corticopontine fibers of the cerebral peduncles. The inferior cerebellar peduncle mainly carries inputs to the cerebellum from the spinal cord.

Answer 193

located in the brainstem tegmentum. Term "reticular" means net-like or mesh-like in appearance. a central core of nuclei that run through the entire length of the brainstem. It is continuous rostrally with a certain diencephalic nuclei and caudally with the intermediate zone of the spinal cord. Simplifying somewhat, we can say that these rostral and caudal extensions highlight the two main functions of the RF. Thus, the rostral RF of the mesencephalon and upper pons function together with diencephalic nuclei to maintain an alert conscious state in the forebrain. Meanwhile, the caudal RF of the pons and medulla works together with the cranial nerve nuclei and the spinal cord to carry out a variety of important motor, reflex, and autonomic functions.

Answer 194

AAA -Alertness, Attention, Awareness - alertness depends on normal functioning of the brainstem and diencephalic arousal circuits and the cortex. - Attention appears to use many of these same circuits, together with additional processing in frontoparietal association cortex, and other systems. awareness is poorly understood, but leads to our subjective and personal experience. Conscious awareness depends on our ability to combine various higher-order forms of sensory, motor, emotional, and mnemonic information from disparate regions of the brain into a unified and efficient summary of mental activity.

Answer 195

Classically, coma is caused by either dysfunction of the upper brainstem reticular formation and related structures or by dysfunction of extensive bilateral regions of the cerebral cortex.

Answer 196

an abnormal tendency to easily enter REM sleep directly from the waking state (compare to the normal sleep stages), which is associated with four classic clinical findings: 1. excessive daytime sleepiness 2. cataplexy (sudden loss of muscle tone from the awake state, often in response to an emotional stimulus) 3. hypnagogic (while falling asleep) or hypnopompic (while awakening) dreamlike hallucinations 4. sleep paralysis (awakening, but remaining unable to move for several minutes)

Answer 197

unarousable unresponsiveness in which the patient lies with eyes closed. Minimum durations is 1 hour to distinguish coma from transient disorders of consciousness such as concussion or syncope. there is profoundly impaired function of the cerebral cortex and diencephalic-upper brainstem arousal systems. Many simple or even complex brainstem reflex activities may occur in coma. However, psychologically meaningful or purposeful responses mediated by the cortex are absent. Cerebral metabolism is typically reduced by at least 50%, in agreement with the lack of significant cortical functions. Coma can be induced by cortical or subcortical pathology, but once coma is present, both cortical and subcortical arousal systems are depressed. EEG is abnormal but can show many different patterns. this is generally not a permanent condition. within 2-4 weeks of onset, nearly all patients either deteriorate or emerge into other states of less profoundly impaired arousal.

Answer 198

may be considered an extreme and irreversible form of coma. defined on the basis of clinical examination demonstrating no evidence of forebrain or brainstem function, including no brainstem reflexes. Only spinal cord reflexes may persist. EEG shows "electrocerebral inactivity" or a flat pattern, less than 2 microvolts in amplitude. cerebral perfusion and metabolism are likewise reduced to zero.

Answer 199

a perplexing state in which patients regain sleep-wake cycles and other primitive orienting responses and reflexes mediated by the brainstem and diencephalon but remain unconscious. this can also occur in certain end-stage dementias, as well as neurodegenerative or congenital disorders. If duration is longer than 1 month it is called a persistent vegetative state. If one remains in this state longer than 3 months following non-traumatic causes or longer than 12 months following traumatic causes, prognosis for recovery is very poor. like coma, there is no meaningful response to stimuli, and they have diffuse cortical dysfunction evidenced by over 50% reduction in cerebral metabolism. but they do open their eyes and arouse in response to simulation, presumably through brainstem and diencephalon-mediated pathways. They may produce unintelligible sounds and move their limbs, but they do not have meaningful speech or gestures, do not make purposeful movements, do not track visual stimuli, and are incontinent.

Answer 200

appearance of visual tracking may be one of the earliest signs of emergence into minimally conscious state from vegetative state. In this state, patients have some minimal or variable degree of responsiveness, including the ability to follow simple commands, say single words, or reach for and hold objects. by definition, they do not have reliable interactive verbal or nonverbal communication and do not have reliable functional use of objects.

Answer 201

akinetic mutism, abulia, and catatonia. can resemble coma or vegetative states. these disorders have in common the dysfunction of circuits involving the frontal lobes, diencephalon, and ascending dopaminergic projections important to the initiation of motor and cognitive activity. -akinetic mutism: patient appears fully awake and the patietns visually track the examiner. however, they usually do not respond to any commands. primary deficit is in motor initiation rather than in consciousness, akinetic mutism differs from minimally conscious state. can be viewed as extreme form of abulia, often resulting from frontal lesions. Catatonia is a similar akinetic state that can occasionally be seen in advanced cases of schizophrenia. Again, frontal lobe and dopaminergic dysfunction have been implicated.

Answer 202

continuous seizure activity. usually clinically obvious, but sometimes only subtle twitching or no motor activity at all is present. EEG performed in a series of patients in coma revealed that 20% of cases had status epilepticus.

Answer 203

medulla. Lesions here disrupt respiratory circuits and can cause respiratory arrest and death.

Answer 204

arises from the top of the basilar artery, just beyond the SCA (superior cerebellar artery). The PCA then wraps around the midbrain, supplying it, as well as most of the thalamus, medial occipital lobes, and inferior-medial temporal lobes.

Answer 205

Signs of brain-stem involvement over hemispheric: crossed signs, such as decreased sensation on one side of the face and contralateral body, or weakness on one side of the face and contralateral body, and cranial nerve abnormalities, especially those causing eye movement abnormalities, such as dysconjugate gaze, wrong-way eyes, pupillary abnormalities, or nystagmus. Signs of hemispheric over brainstem: aphasia, hemineglect, hemianopia, and seizures

Answer 206

The paired vertebral arteries arise from the subclavian arteries at the base of the neck and then ascend through the foramina transversaria of cervical vertebrae C6 through C2. They then take a winding course around the lateral aspect of the first cervical vertebra before piercing the dura and entering the cranial cavity via the foramen magnum. The vertebral artery is run along the ventral aspect of the medulla and join at the pontomedullary junction to form a single basilar artery. The basilar artery continues rostrally, running along the ventral surface of the ponds, before splitting at the pontomesencephalic junction into the two posterior cerebral arteries, which connect via the posterior communicating arteries (pcomm) to the internal carotid arteries of the anterior circulation.

Answer 207

Face, hands, arms, trunk are on the lateral convexities, while the leg and foot areas are in the interhemispheric fissure.

Answer 208

bilateral internal carotid arteries. Anterior circulation arise from the common carotid arteries originating at the aorta or brachiocephalic arteries the internal carotid branches into the ACA and MCA.

Answer 209

bilateral vertebral arteries, which arise from the subclavian arteriesand then ascend through foramina in the transverse processes of the cervical vertebrae (foramina transversaria) before entering the foramen magnum and joining to form the basilar artery. the top of the basilar feeds into the PCAs.

Answer 210

connects the two anterior cerebral arteries (ACA)

Answer 211

links the anterior and posterior circulations by connecting the internal carotids to the PCAs

Answer 212

anterior cerebral artery passes forward to travel in the interhemispheric fissure as it sweeps back and over the corpus callosum. Two major branches commonly seen are the pericallosal and callosomarginal arteries. The ACA supplies most of the cortex on the anterior medial surface of the brain, from the frontal to the anterior parietal lobes, usually including the medial sensorimotor cortex.

Answer 213

Middle Cerebral Artery turns laterally to enter the depths of the Sylvian fissure. Within the Sylvian fissure it usually bifurcates into the superior division and the inferior division (but varies to even 3 or 4 branches). The branches of the MCA form loops as they pass over the insula and then around and over the operculum to exit the Sylvian fissure onto the lateral convexity. The superior division supplies the cortex above the sylvian fissure, including the lateral frontal lobe and usually including the peri-Rolandic cortex. The inferior division supplies the cortex below the Sylvian fissure, including the lateral temporal lobe and a variable portion of the parietal lobe. The MCA thus supplies most of the cortex on the dorsolateral convexity of the brain.

Answer 214

posterior cerebral artery curves back after arising from the top of the basilar and sends branches over the inferior and medial temporal lobes and over the medial occipital cortex. The PCA territory therefore includes the inferior and medial temporal and occipital cortex.

Answer 215

small vessels that arise from the initial portions of the MCA at the base of the brain. They are before the MCA enters the Sylvian fissure, and they penetrate the anterior perforated substance to supply large regions of the basal ganglia and internal capsule. Recall that the posterior limb of the internal capsule contains important motor pathways through the corticobulbar and corticospinal tracts. thus infarction often causes contralateral hemiparesis. In hypertension, these and other similar small vessels are particularly prone to narrowing, which can lead to lacunar infarction, as well as to rupture, causing intracerebral hemorrhage.

Answer 216

arises from the internal carotid artery. Its territory includes portions of the globus pallidus, putamen, thalamus (sometimes involving the LGN), and the posterior limb of the internal capsule extending up to the lateral ventricles. Recall that the posterior limb of the internal capsule contains important motor pathways through the corticobulbar and corticospinal tracts. thus infarction often causes contralateral hemiparesis.

Answer 217

comes off the initial portion of the ACA to supply portions of the head of the caudate, anterior putamen, globus pallidus, and internal capsule.

Answer 218

small, penetrating arteries that arise from the proximal posterior cerebral arteries near the top of the basilar artery (as does the thalamogeniculate and posterior choroidal arteries). They supply the thalamus and sometimes extend to a portion of the posterior limb of the internal capsule. Small penetrating vessels arising from the top of the basilar also supply the midbrain.

Answer 219

MCA. at least in part due to the relatively large territory supplied by the MCA. Infarcts here can occur in the superior division, inferior division, or deep territory.

Answer 220

Right face and arm weakness of the UMN type and a nonfluent, or Broca's apashia. in some cases, can also be face and arm cortical-type sensory loss.

Answer 221

Fluent, or Wernicke's, aphasia and a right visual field deficit. May also be some right face and arm cortical-type sensory loss. Motor findings are usually absent, and patients may initially seem confused or crazy but otherwise intact, unless carefully examined. Some mild right-sided weakness may be present, especially at the onset of symptoms.

Answer 222

Right pure motor hemiparesis of the UMN type. Larger infarcts may produce "cortical" deficits, such as aphasia as well.

Answer 223

combo of deficits seen in left superior and inferior division and deep territory infarcts, with right hemplegia, right hemianesthesia, right homonymous hemianopia, and global aphasia. There is often a left gaze preference, especially at the onset, caused by damage to left hemi cortical areas important for driving the eyes to the right.

Answer 224

left face and arm weakness of the UMN type. Left hemineglect is present to a variable extent. In some cases, may also be some left face and arm cortical-type sensory loss.

Answer 225

Profound left hemineglect. Left visual field and somatosensory deficits are often present; however, these may be difficult to test convincingly because of the neglect. Motor neglect with decreased voluntary or spontaneous initiation of movements on the left side can also occur. however, even patients with left motor neglect usually have normal strength on the left side, as evidenced by occasional spontaneous movements on purposeful withdrawal from pain. Some mild, left-sided weakness may be present. There is often a right gaze preference, especially at onset.

Answer 226

Left pure motor hemiparesis of the UMN type. Larger infarcts may produce "cortical" deficits, such as left hemineglect as well.

Answer 227

Combo of the deficits seen in higher portions of right MCA strokes, with left hemiplegia, left hemianesthesia, left homonymous hemianopia, and profound left hemineglect. There is usually a right gaze preference, especially at the onset, caused by damage to right hemi cortical areas important for driving the eyes to the left.

Answer 228

right leg weakness of the UMN type and right leg cortical-type sensory loss. Grasp reflex, frontal lobe behavioral abnormalities, and transcortical aphasia can also be seen. Larger infarcts may cause right hemiplegia.

Answer 229

Left leg weakness of the UMN type and left leg cortical-type sensory loss. Grasp reflex, frontal lobe behavioral abnormalities, and left hemineglect can also be seen. Larger infarcts may cause left hemiplegia.

Answer 230

right homonymous hemianopia. Extension to the splenium of the corpus callosum can cause alexia without agraphia. Larger infarcts, including the thalamus and internal capsule, may cause aphasia, right hemisensory loss, and right hemiparesis.

Answer 231

Left homonymous hemianopia. Larger infarcts including the thalamus and internal capsule may cause left hemisensory loss and left hemiparesis.

Answer 232

small, deep infarcts involving penetrating branches of the MCA or other vessels are called lecunes.

Answer 233

typically produce UMN-type weakness and cortical-type sensory loss affecting the contralateral leg more than the arm or face. Larger ACA strokes may cause contralateral hemiplegia, at least initially. Dominant ACA strokes sometimes are associated with transcortical motor aphasia, and non-dominant ACA strokes can produce contralateral neglect. There may also be a variable degree of frontal lobe dysfunction depending, in part, on the size of the infarct. Such dysfunction may include a grasp reflex, impaired judgment, flat affect, apraxia, abulia, and incontinence. Sometimes damage to the supplementary motor area and other regions in the frontal lobe leads to an unusual "alien hand syndrome" characterized by semiautomatic movements of the contralateral arm that are not under voluntary control.

Answer 234

PCA infarcts typically cause a contralateral homonymous hemianopia. Smaller infarcts that do not involve the whole PCA territory may cause smaller homonymous visual field defects. Sometimes the small, penetrating vessels that come off the proximal PCA are involved, leading to infarcts in the thalamus or posterior limb of the internal capsule. The result can be a contralateral sensory loss; contralateral hemiparesis; or even thalamic aphasia if the infarct is in the dominant (usually left) hemisphere, thereby mimicking features of MCA infarcts. PCA infarcts that involve the left occipital cortex and the splenium of the corpus callosum can produce alexia without agraphia. Small, perforating vessels arising from the proximal PCAs at the top of the basilar artery supply the midbrain.

Answer 235

regions between two cerebral arteries that are most susceptible to ischemia and infarction. Bilateral watershed infarcts in both the ACA-MCA and MCA-PCA watershed zones can occur with severe drops in systemic blood pressure. A sudden occlusion of an internal carotid artery or a drop in BP in a patient with carotid stenosis can cause an ACA-MCA watershed infarct, since the MCA and ACA are both fed by the carotid. watershed infarcts can produce proximal arm and leg weakness ("Man in the barrel" syndrome) b/c the regions of the homunculus involved often include the trunk and proximal limbs. In the dominant hemisphere, watershed infarcts can cause transcortical aphasia syndromes. MCA-PCA watershed infarcts can cause disturbances of higher-order visual processing. In addition to watershed infarcts between the superficial territories of different cerebral vessels, watershed infarcts can also occasionally occur between the superficial and deep territories of the MCA.

Answer 236

TIA, migraine, seizure, and other non-neurologica causes such as cardiac arrhythmia or hypoglycemia.

Answer 237

(TIA) classically defined as neurologic deficit lasting less than 24 hours, caused by temporary brain ischemia. However, more typical duration is about 10 minutes and imaging studies are showing that events lasting more than 10 min probably produce at least some permanent cell death in the involved region of the brain. TIA lasting more than an hour, in fact, are usually small infarcts. Despite appearance on MRI, complete functional recovery can sometimes occur within a day. Either way, TIAs are important warning sign for a potentially larger ischemic injury to the brain. TIAs are a neurological emergency. Approximately 15% of patients with TIAs will have a stroke causing persistent deficits within 3 months, and about half of these stroke occur within the first 48 hours.

Answer 238

- embolus temporarily occludes the blood vessel but then dissolves, allowing return of blood flow before permanent damage occurs. - in situ thrombus formation on the blood vessel wall and/or vasospasm leading to temporary narrowing of the blood vessel lumen.

Answer 239

Most common cause is cardiogenic syncope, including vasovagal transient episodes of hypotension (“fainting”), and other non neurologic causes. Neurologic causes are responsible for less than five to 10% of cases of syncope and include seizures.

Answer 240

A piece of material, Usually a blood clot, is formed in one place and then travels through the bloodstream to suddenly lodge in and occlude a blood vessel, supplying the brain. Considered to occur suddenly with maximal deficits at onset. In embolic infarcts, the goal is to determine the source of the embolus so that future strokes may be prevented. In Cardioembolic infarcts, the embolus originates in the heart. These occur in conditions such as atrial fibrillation- In which thrombi form in the fibrillating left atrial appendage, Myocardial infarction- in which thrombi form on hypokinetic or akinetic regions of infarcted myocardium, And valvular disease or mechanical prostheses- In which thrombi form on the valve leaflets or prosthetic parts.

Answer 241

A blood clot is formed locally on the blood vessel wall, usually at the side of an underlying atherosclerotic plaque, causing The vessel to occlude. May have a more stuttering course.

Answer 242

May be distinguished clinically based on the absence or presence of cortical signs, Including aphasia neglect, homonymous visual field defects, and cortical sensory loss. However each of these deficits can be seen in some cases of subcortical lesions as well. Presence of atypical lacunar syndrome, such as pure motor hemiparesis, suggest that a subcortical lesion is present.

Answer 243

present in 25-30% of ischemic strokes. When unilateral, it is more common on the side of the infarct, although exceptions do occur. Headaches may be more common for posterior than for anterior circulation infarcts. headaches or neck pain are also seen in dissection of the carotid or vertebral arteries.

Answer 244

hypertension, diabetes, hypercholesterolemia, cigarette smoking, family history, or prior stroke or other vascular disease. afib, mechanical or other valve abnormalities, patent foramen ovale, and a severely decreased ejection fraction.

Answer 245

1. CT to rule out hemorrhage. REMEMBER an ischemic infarct will often not be visible on the initial CT, especially i it is done within a few hours of symptom onset; however, a hemorrhage will almost always be visible. - complete routine blood chemistries, cell counts, and coagulation studies. - once hemorrhage is ruled out, pt may be eligible for treatment with the thrombolytic agent tissue plasminogen activator (tPA). can improve outcomes if given within 4.5 hours of stroke. this does increase risk of hemorrhage and is contraindicated if prior hisotry of hemorrhage, aneurysm, active internal bleeding, abnormal platelet or coagulation studies on blood tests, and uncontrolled hypertension. if not eligible for tPA or in TIAs, acute admin of aspirin can reduce risk of early recurrent stroke. must ask about vascular risk factors and stroke risk. blood flow in the major cranial and neck vessels should be assessed with Doppler ultrasound and/or magnetic resonance angiography (MRA) or CT angiography (CTA). possibility of cardioembolic source investigated with an electrocardiogram to look for evidence of cardiac eschemia or arrhythmias, and an echocardiogram, to look for structural abnormalities or thrombi.

Answer 246

occurs with increased frequency in pregnant women and within the first few weeks post partum. obstruction of venous drainage usually causes elevated intracranial pressure. back pressure in cortical veins can cause parasagittal hemorrhages. increased venous pressure can decrease cerebral perfusion, leading to infarcts. seizures are common. patients often have headaches and pailledema, and may have depressed level of consciousness. empty delta sign may be seen on imaging, which is central, darker-filling defect in the sinus.

Neuroanatomy Flashcards

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