Neuroscience Flashcards

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1
Q

Dsyfunction of Broca vs. Wernicke areas (dominant hemisphere)

A

Dysfunction of Broca’s area → expressive/motor aphasia characterized by slow speech consisting primarily of nouns and verbs (agrammatism) and preserved speech comprehension; patients are often frustrated because they are aware of their problem

Dysfunction of Wernicke’s area → receptive/sensory aphasia characterized by impaired comprehension and fluent aphasia (speech flows readily but is meaningless); patients often lack insight into their problem

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2
Q

Embryonic derivation of microglia cells?

A

Mesoderm

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3
Q

Embryonic derivation of CNS vs. PNS structures

A

CNS neurons, ependymal cells, oligodendroglia, and astrocytes → neuroectoderm

PNS neurons, Schwann cells → neural crest

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4
Q

Embryologic derivation of optic nerve and tract

A

Neural ectoderm → diencephalon

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5
Q

What bones are formed from pharyngeal arch I?

A

Maxilla

Part of temporal bone

Mandible

Malleus

Incus

Sphenomandibular ligament

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6
Q

What bones are formed from pharyngeal arch II?

A

Upper part of hyoid

Stapes

Styloid

Stylohyoid ligament

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7
Q

What bones are formed from pharyngeal arch III?

A

Rest of hyoid

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8
Q

What bones are formed from pharyngeal arch IV and VI?

A

Laryngeal cartilages

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9
Q

What muscles are formed from pharyngeal arch I?

A

Muscles of mastication

Mylohyoid

Anterior belly of digastric

Tensor tympani

Tensor veli palatini

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10
Q

What muscles are formed from pharyngeal arch II?

A

Muscles of facial expression

Stapedius

Stylohyoid

Posterior belly of digastric

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11
Q

What muscles are formed from pharyngeal arch III?

A

Stylopharyngeus

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12
Q

What muscles are formed from pharyngeal arch IV?

A

Pharyngeal constrictors

Salpingopharyngeus

Palatopharyngeus

Levator veli palatini

Palatoglossus

Cricothyroid

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13
Q

What muscles are formed from pharyngeal arch VI?

A

Remaining laryngeals (except cricothyroid)

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14
Q

Which nerve innervates pharyngeal arch I?

A

CN V3 (mandibular nerve)

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15
Q

Which nerve innervates pharyngeal arch II?

A

CN VII (facial nerve)

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16
Q

Which nerve innervates pharyngeal arch III?

A

CN IX (glossopharyngeal nerve)

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17
Q

Which nerve innervates pharyngeal arch IV?

A

CN X (vagus nerve)

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18
Q

Which nerve innervates pharyngeal arch VI?

A

CN X (recurrent laryngeal nerve of vagus nerve)

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19
Q

Pharyngeal pouches

A

1st → auditory tube

2nd → tonsillar crypt

3rd → inferior parathyroids, thymus

4th → superior parathyroids, C cells of thyroid

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20
Q

Innervation of the tongue

A

Anterior tongue → V3 (sensation), VII (taste)

Middle tongue → IX (sensation and taste)

Posterior tongue → X (sensation and taste)

Motor → XII

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21
Q

Acoustic neuroma

A

Benign proliferation of Schwann cells

Typically located in internal acoutic meatus (CN VIII)

If bilateral, strongly associated with neurofibromatosis type 2

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22
Q

Oligodendrocytes vs. Schwann cells

A

Oligodendrocytes → myelinates multiple axons in the CNS; degeneration causes MS, PML, leukodystrophies

Schwann cells → myelineates one axon in the periphery; denegeneration causes Guillain-Barre

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23
Q

Epidural vs. subdural hematoma

A

Epidural hematoma → biconvex blood collection that doesn’t cross suture lines, rupture of middle meningeal artery

Subdural hematoma → crescent-shaped hemorrhage that crosses suture lines, midline shifts, rupture of bridging veins

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24
Q

Normal pressure hydrocephalus

A

Decreased CSF absorption by arachnoid granulations → communicating hydrocephalus

Imaging: ventriculomegaly out of proportion to or without corresponsding sulci enlargement

Triad: urinary incontinence (stretching of descending cortical fibers → decreased inhibitory control of bladder contractions), ataxia, cognitive dysfunction (“wet, wobbly, and whacky”)

Tx: removal of CSF

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25
Q

Where to place the needle for lumbar puncture?

A

Between L3 and L5

(“To keep the cord alive, keep the spinal needle between L3 and L5”)

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26
Q

Lower vs. upper motor neuron lesions

A

Lower motor neuron lesions

Flaccid paralysis

Fasciculations

Reduced muscle tone

Reduced myotatic reflex

Rapid atrophy

Upper motor neuron lesions

Spastic paralysis

Increased muscle tone

Exaggerated myotatic reflex

Increased resistance to passive stretch

Babinski sign

Slow atrophy

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27
Q

Poliomyelitis

A

Lesions in spinal anterior horns → ipsilateral lower motor neuron signs

Similar features seen in spinal muscular atrophy (Werdnig-Hoffman disease) → “floppy baby” with hypotonia and tongue fasciculations

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28
Q

What causes spinal anterior horn lesions?

A

Poliomyelitis

West Nile

Spinal muscular atrophy

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29
Q

Amyotrophic lateral sclerosis

A

ALS AKA Lou Gehrig disease is caused by a defect in superoxide dismutase I

Riluzole modestly increases survival by decreasing presynaptic glutamate release

Lesions in lateral corticospinal tract and anterior horns → combined UMN and LMN signs → fasiculations with eventual atrophy and weakness of the hands

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30
Q

What cranial nerves traverse the cavenous sinus?

A

CN III

CN IV

CN VI

CN V1

CN V2

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31
Q

What goes through the optic canal?

A

CN II (optic nerve) Ophthalmic artery

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32
Q

What goes through the superior orbital fissure?

A

CN III (occulomotor nerve)

CN IV (trochlear nerve)

CN V1 (ophthalmic nerve)

CN VI (abducens nerve)

Ophthalmic vein

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33
Q

What goes through the foramen rotundum?

A

CN V2 (maxillary nerve)

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34
Q

What goes through the foramen ovale?

A

CN V3 (mandibular nerve)

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35
Q

What goes through the foramen spinosum?

A

Middle meningeal artery Meningeal nerve (V3)

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36
Q

What goes through the internal acoustic meatus?

A

CN VII (facial nerve)

CN VIII (vestibulocochlear nerve)

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37
Q

What goes through the jugular foramen?

A

CN IX (glossopharyngeal nerve)

CN X (vagus nerve)

CN XI (spinal accessory nerve) exits

Inferior petrosal sinus

Jugular bulb

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38
Q

What goes through the hypoglossal canal?

A

CN XII (hypoglossal nerve)

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39
Q

What goes through the foramen magnum?

A

Brain stem/spinal cord junction

CN XI (spinal accessory nerve) enters

Vertebral arteries

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40
Q

Lesion of the angular gyrus of the dominant parietal lobe (often left lobe)

A

Supplied by MCA

Gerstmann syndrome: agraphia, acalculia, finger agnosia, left-right disorientation

41
Q

Cranial nerve most likely to be affected by lesion at the middle cerebellar peduncles

A

CN V

42
Q

Where is the lesion that causes hemiballism

A

Lesion (e.g. lacunar stroke) in contralateral subthalamic nucleus

Hemiballism - sudden, wild flailing of one arm ± ipsilateral leg

43
Q

Wernicke encephalopathy and Korsakoff syndrome

A

Wernicke encephalopathy = ataxia, nystagmus, opthalmoplegia, anterograde amnesia

Korsakoff syndrome (temporal lobes) = anterograde and retrograde amnesia (usually permanent), apathy, lack of insight, confabulation

Caused by thiamine deficiency (often secondary to chronic alcoholism and malnutrition) → administration of dextrose can exacerbate thiamine deficiency so always supplement first (thiamine is a cofactor for glycolytic enzymes pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, transketolase)

A/w necrosis of mammillary bodies

Dx: low erythrocyte transketolase activity

Chronic alcoholism may also cause cerebellar atrophy/degeneration → wide-based gait ataxia, truncal instability, intention tremor

44
Q

Interventricular hemorrhage

A

Hemorrhage of the germinal matrix into the lateral ventricles as a complication of premature birth

Symptoms may include bulging anterior fontanelle, hypotension, decerebrate posturing, tonic-clonic seizures, irregular respirations, coma

45
Q

Lesions of the cerebellum

A

Lateral cerebellum → ipsilateral dysdiadochokinesia, limb dsmetria, intension tremor, propensity to fall towards injured side

Medial cerebellum (vermis) → bilateral truncal ataxia, nystagmus, head tilting, wide-based gait

46
Q

Dopaminergic pathways in the brain

A

Mesolimbic (ventral tegmental area to limbic system) → ↑ D2 activity leads to positive symptoms of schizophrenia

Mesocortical (ventral tegmental area to cortex) → ↓ dopaminergic activity leads to negative symptoms of schizophrenia

Nigrostriatal (substantia nigra to the caudate nucleus and putamen) → ↓ dopaminergic activity leads to Parkinsons

Tuberoinfundibular (hypothalamus to pituitary) → ↓ D2 activity leads to hyperprolatinemia

47
Q

Principles sites of norepinephrine, serotonin, and dopamine synthesis

A

Norepinephrine → locus ceruleus (posterior rostral pons)

Serotonin → raphe nucleus (pons, medulla, midbrain)

Dopamine → ventral tegmental area, substantia nigra pargs compacta (midbrain)

48
Q

Innervation of the eye muscles

A

LR6SO4R3

CN VI (abducens): lateral rectus

CN IV (trochlear): superior oblique

CN III (oculomotor): medial rectus, superior rectus, inferior rectus, inferior oblique

49
Q

Palsies of the cranial nerves involved in eye movements

A

CN III (oculomotor) palsy → vertical and horizontal diplopia, ptosis, enlarged and nonreactive pupil, eye is “down and out”

CN VI (abducens) palsy → weakness of lateral rectus → horizontal diplopia

CN IV (trochlear) palsy → weakness of superior oblique → verticle diplopia worse when towards the nose, patient may tilt head away from affected eye

50
Q

Alzheimers disease

A

Widespread cortical atrophy (narrowing of gyri and widening of sulci) with decreased acetylcholine levels 2/2 deficiency of choline acetyltransferase

Early onset risk factors (before age 60)

Down Syndrome (extra amyloid precursor protein gene on chromosome 21), presenilin 1 gene (chromosome 14), presenilin 2 gene (chromosome 1) → all promote production of Aβ amyloid

Late onset risk factors (after age 60)

ε4 allele of apolioprotein E → senile plaques?

Protective factors

ε2 allele of apolioprotein E

51
Q

Huntington disease

A

AD caused by CAG trinucleotide repeats (chromosome 4) → huntingtin protein → increased histone deacetylation → transcriptional silencing of genes necessary for neuronal survival

Characterized by choreiform movements, aggression, depression, and dementia

Decreased levels of GABA and acetylcholine

Atrophy of the caudate nuclei

52
Q

Arnold-Chiari malformation

A

Arnold-Chiari I: small cerebellar tonsillar ectopia, may be asymptomatic or cause headaches, associated with syringomyelia

Arnold-Chiari II: significant herniation of the cerebellar tonsils and the vermis through the foramen magnum with aqueductal stenosis and hydrocephalus

53
Q

Dandy-Walker

A

Agenesis of cerebellar vermis with cystic enlargement of the 4th ventricle

54
Q

Syringomyelia

A

Cystic cavity within the spinal cord

Anterior spinal commissural fibers damaged → “cape-like” bilateral loss of pain and temperature sensation in upper extremities

A/w Chiari I malformation

55
Q

Function of the supraoptic nucleus of the hypothalamus

A

Makes ADH

56
Q

Function of the paraventricular nucleus of the hypothalamus

A

Makes oxytocin and anterior pituitary hormones (CRH, TRH)

57
Q

Function of the ventromedial nucleus of the hypothalamus

A

Mediates satiety → stimulated by leptin

Destruction causes hyperphagia

(“Zap the ventromedial nucleus and you’ll grow ventrally”)

58
Q

Function of the lateral nucleus of the hypothalamus

A

Mediates hunger → inhibited by leptin

Destruction causes anorexia, failure to thrive

(“If you zap the lateral nucleus, you shrink laterally”)

59
Q

Function of the anterior nucleus of the hypothalamus

A

Mediates cooling (parasympathetic)

Destruction leads to hyperthermia

(“Anterior nucleus = A/C”)

60
Q

Function of the posterior nucleus of the hypothalamus

A

Mediates heating (sympathetic)

Destruction leads to hypothermia

61
Q

Function of the suprachiasmatic nucleus of the hypothalamus

A

Circadian rhythm regulation and pineal gland function

62
Q

Function of the arcuate nucleus of the hypothalamus

A

Secretion of dopamine, GHRH, GRH

63
Q

Parkinsons disease

A

Loss of dopaminergic neurons in the substantia nigra pars compacta

Characterized by resting tremors (pill-rolling), cogwheel rigidity, bradykinesia/akinesia, postural instability, shuffling gait

Associated with Lewy bodies (α-synuclein intracellular eosinophilic inclusions)

64
Q

Kluver-Bucy syndrome

A

Bilateral amygdala damage

Characterized by hyperorality, hypersexuality, disinhibited behavior

Associated with HSV-1

65
Q

Lesion of the angular gyrus of the non-dominant parietal lobe (often right lobe)

A

Spatial neglect syndrome (agnosia of the contralateral side of the world)

66
Q

Central pontine myelinolysis

A

Axonal demyelination in the pontine white matter tracts secondary to osmotic forces and edema

Characterized by acute paralysis, dysarthria, dysphagia, diplopia, loss of consciousness, “locked-in” syndrome

Caused by rapid correction of hyponatremia

Rapid correction of hypernatremia = cerebral edema

67
Q

Berry aneurysms

A

Anterior communicating > posterior communicating (a/w CN III palsy)

Associated with ADPKD, Marfan syndrome, Ehlers-Danlos

68
Q

Brown-Sequard sequence

A

Caused by hemisection of the spinal cord

Ipsilateral impaired motor function, proprioception, vibration

Contralateral impaired pain and temperature sensation

69
Q

Nerve roots associted with clinical reflexes

A

S1, 2 buckle my shoe (Achilles)

L3, 4 kick the door (patellar)

C5, 6 pick up sticks (biceps)

C7, 8 lay them strait (triceps)

S3, 4 anal wink

L1, 2 cremaster

70
Q

Describe the tonotopy of the cochlea?

A

High frequency heard best at the base of the choclea near the oval window

Low frequency heard best at the apex near the helicotrema

71
Q

Visual field deficits

A
72
Q

Frontotemporal dementia (Picks disease)

A

Characterized by dementia, asphasia, parkinsonian features, change in personality

Associated with frontotemporal atrophy, pick bodies (tau protein aggregates)

73
Q

Lewy body dementia

A

Characterized by parkinsonian symptoms, dementia, visual hallucinations

Associated with α-synuclein defect

74
Q

Multiple sclerosis

A

Autoimmune inflammation and demyelination of the CNS

Characterized by neurologic deficits separated by space and time (relapsing and remitting course)

Symptoms may include scanning speech, intention tremor, incontinence, internuclear ophthalmoplegia, nystagmus, optic neuritis

Dx: oligoclonal IgG in CSF, periventricular plaques on MRI (lipid laden macrophages containing the products of myeline breakdown, loss of myelin sheaths, depletion of oligodendrocytes)

Tx: IFN-β, immunosuppression, natalizumab

75
Q

Guillain-Barre

A

Acute inflammatory demyelinating polyradiculopathy caused by autoimmune destruction of Schwann cells that causes demyelination of peripheral nerves with endoneural inflammatory infiltration

Characterized by symmetric ascending muscle weakness/paralysis beginning in the lower extremities

Associated with URI or GI infection (esp. Campylobacter jejuni and CMV)

76
Q

Progressive multifocal leukoencephalopathy

A

Demyelination of CNS due to destruction of oligodendrocytes

Associated with JC virus and AIDS

77
Q

Metachromatic leukodystrophy

A

Autosomal recessive lysosomal storage disease due to arylsulfatase A deficiency

Characterized by central and peripheral demyelination with ataxia and dementia due to build-up of sulfatide which impairs producion of the myelin sheath

78
Q

Krabbe disease

A

Autosomal recessive lysosomal storage disease due to deficiency of galactocerebrosidase

Build of up galactocerebroside and psychosine destroys myelin

Characterized by peripheral neuropathy, developmental delay, optic atrophy, and globoid cells

79
Q

Adrenoleukodystrophy

A

X-linked disease due to impaired metabolism of long chain fatty acids

Accumulation damages white matter and adrenal glands

80
Q

Glioblastoma multiforme (grade IV astrocytoma)

A

Malignant tumor of astrocytes (GFAP +)

Gross features: can cross corpus callosum (“butterfly glioma”)

Histologic features: “Pseudopalasading”

Prognosis: poor

81
Q

Pilocytic astrocytoma

A

Benign tumor of astrocytes (GFAP +)

Gross features: well circumscribed, often found in posterior fossa, cystic + solid

Histologic features: Rosenthal fibers (eosinophilic, corkscrew fibers)

Prognosis: good

82
Q

Meningioma

A

Benign tumor of arachnoid cells

Gross features: dural attachment (“tail”),

Histologic features: Spindle cells concentrically arranged in a whorled pattern, psamomma bodies

83
Q

Oligodendroglioma

A

Tumor of oligodendrocytes (GFAP +)

Gross features: most often in frontal lobes, often calcified

Histologic features: “Fried egg” cells with round nuclei and clear cytoplasm

84
Q
A
85
Q

Schwannoma

A

Tumor of Schwann cells (S-100+)

Gross features: usually found at the cerebellopontine angle, often localized to CN VIII (acoustic neuroma)

Histology: highly cellular areas with palisading (Antoni A) interspersed with nuclear-free zones (Verocay body) intermixed with myxoid regions of low cellularity (Antoni B)

Bilateral acoustic neuroma (tinnitus, vertigo, sensorineural hearing loss) associated with neurofibromatosis type II

86
Q

Medulloblastoma

A

Malignant tumor of primitive neuroectoderm

Gross features: located in the cerebellum, can compress 4th ventricle causing hydrocephalus, can send drop metastases to the spinal cord

Histologic features: Homer-Wright rosettes, small blue cells

87
Q

Ependymoma

A

Tumor of ependymal cells (GFAP +)

Gross features: often found in the 4th ventricle and can cause hydrocephalus

Histologic features: perivascular rosettes, rod-shaped blepharoplasts (basal ciliary bodies) found near nucleus

Prognosis: poor

88
Q

Craniopharyngioma

A

Benign tumor of the remnants of Rathke’s pouch

Gross features: cysts filled with brownish-yellow fluid composed of protein and cholesterol crystals, calcification is common (“enamel-like”)

Histologic features: cysts lined by cords/nests of stratified squamous epithalium with peripheral palisading and niternal areas of lamellar “wet” keratin

89
Q

Gross and histological changes associated with HIV-associated dementia

A

Subcortical atrophy and groups of microglial nodules around small areas of necrosis that may fuse to form multinucleated giant cells

90
Q

Creutzfeldt-Jakob disease

A

Abnormal folding of proteins from α-helices to β-pleated sheets (reorganization of hydrogen bonds) that are resistant to degradation by proteases → PrP accumulates in extracellular space

Characterized by rapidly progressive dementia and myoclonic jerks

Mostly iatrogenic (contaminated corneal transplants, implantable electrodes, growth hormones)

On histology, spongiform encephalopathy (vacuoles in the cytoplasm of neutrophils and neurons → cysts)

91
Q

Types of seizures

A

Focal seizures (involves one hemisphere at onset)

Simple: no loss of consciousness or postictal state

Complex: loss of consciousness and postictal state, may have automatisms (e.g. lip smacking)

Generalized seizures (involves both hemispheres at onset)

Tonic-clonic: loss of consciousness and postictal state, diffuse muscle contraction of limbs (tonic) followed by rhythmic jerking (clonic)

Myoclonic: no loss of consciousness or postictal state, brief jerking movements

Absence: brief loss of consciousness (e.g. blank stare), may have automatism, usually no postictal state

92
Q

Lacunar infarcts vs. Charcot-Bouchard aneurysms

A

Lacunar infarcts: small ishchemic infarct (< 15 mm) involving deep brain structures associated with chronic HTN which promotes lipohyalinosis, microatheroma formation → hypertensive arteriolar sclerosis

Charcot-Bouchard aneurysms: caused by chronic hyprtension involving the same penetrating arterioles as lacunar strokes but typically lead to intraparenchymal hemorrhage in deep brain structures

93
Q

Most common cause of intracranial hemorrhage in children vs. elderly

A

Children: AV malformation

Elderly: cerebral amyloid angiopathy, most often affects occipital and parietal lobes

94
Q

Autonomic nervous system receptors and neurotransmitters

A

All preganglionic receptors are nicotinic and use ACh as a neurotransmitter (including adrenal medulla)

Parasympathetic postganglionic receptors are muscarinic and use ACh as a neurotransmitter

Most sympathetic postganglion receptors are α or β and use norepinephrine as a neurotransmitter (eccrine sweat glands are the exception; they have muscarinic receptors and use ACh as a neurotransmitter)

95
Q

Drug used to prevent vasospasm following a subarachnoid hemorrhage

A

Nimodipine (calcium-channel blocker)

96
Q

Parinaud syndrome

A

Upward gaze palsy, absent pupillary light reflec, impaired conversion

Can be caused by mass effect (e.g. pinealoma) affecting the superior colliculus

97
Q

Pseudotumor cerebri (idiopathic intracranial hypertension)

A

Increased ICP in the absense of a tumor or other disease

Typically presents in young obese women with daily headache, bilaterally symmetric papilledema, and transient visual disturbances related to impaired cerebral venous outflow and elevated intracranial pressure. Build-up in pressure compresses the optic nerve impairing axoplasmic flow.

Symptoms are worse during Valsalva as ICP increases

98
Q

Decerebrate vs. decorticate posturing

A