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Flashcards in Neurology Deck (193):
1

Notochord induces overlying ectoderm to

Notochord induces overlying ectoderm to differentiate into neuroectoderm and form neural plate

2

Neural plate gives rise to

Neural plate gives rise to neural tube and neural crest cells

3

Notochord becomes

Notochord becomes nucleus pulposus of intervetebral disc in adults

4

Prosencephalon gives rise to

Telencephalon and diencephalon

5

Mesencephalon (of the 3 primary vesicles) gives rise to

Mesencephalon

6

Rhombencephalon gives rise to

Metencephalon and myelencephalon

7

Telencephalon gives rise to

Cerebral hemispheres and lateral ventricles

8

Diencephalon gives rise to

Thalamus, hypothalamus, and third ventricle

9

Mesencephalon gives rise to

Midbrain and aqueduct

10

Metencephalon gives rise to

Pon, cerebellum, and upper part of 4th ventricle

11

Myelencephalon gives rise to

Medulla and lower part of 4th ventricle

12

Neuroectoderm

- CNS neurons
- Ependymal cells (inner lining of ventricles, make CSF)
- Oligodendroglia
- Astrocytes

13

Neural crest

- PNS neurons
- Schwann cells

14

Mesoderm

Microglia

15

When do neuropores normally fuse

4th week

16

Confirmatory test for neural tube defect after AFP

↑ acetylcholinesterase (AChE) in amniotic fluid

17

Anencephaly

- Malformation of anterior neural tube → no forebrain, open calvarium
- Clinical findings: ↑ AFP, polyhydramnios (no swallowing center in brain)
- Associated with maternal type 1 diabetes
- Maternal folate supplementation ↓ risk

18

Holoprosencephaly

- Failure of right and left hemispheres to separate
- Usually occurs during weeks 5-6
- May be related to mutations in sonic hedgehog signaling pathway
- Moderate form has cleft lip/palate, most severe form results in cyclopia
- Seen in Patau syndrome and fetal alcohol syndrome

19

Anencephaly is associated with

Maternal type 1 diabetes

20

Holoprosencephaly is associated with

Patau syndrome and fetal alcohol syndrome

21

Chiari II malformation

- Herniation of low-lying cerebellar vermis through foramen magnum with aqueductal stenosis → hydrocephalus
- Usually associated with lumbosacral meningomyelocele (paralysis/sensory loss at and below the level of the lesion)

22

Dandy-Walker syndrome

- Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills the enlarged posterior fossa)
- Associated with noncommunicating hydrocephalus, spina bifida

23

Chiari I malformation

- Cerebellar tonsillar ectopia > 3-5 mm
- Congenital, usually asymptomatic in childhood, manifest with headaches and cerebellar symptoms
- Associated with syringomyelia

24

Tongue development

- 1st and 2nd branchial arches form anterior 2/3 (thus sensation via CN V3, taste via CN VII)
- 3rd and 4th branchial arches form posterior 1/3 (thus sensation and taste mainly via CN IX, extreme posterior via CN X)
- Motor innervation is via CN XII to hyoglossus (retracts and depresses the tongue), genioglossus (protrudes tongue) and styloglossus (draws sides of tongue upward to create a trough for swallowing)
- Motor innervation is via CN X to palatoglossus (elevates posterior tongue during swallowing)

- TASTE → CN VII, IX, X (solitary nucleus)
- PAIN → CN V3, IX, X
- MOTOR → CN X, XII

25

What forms multinucleated giant cells in the CNS of HIV infected patients

HIV-infected microglia fuse to form multinucleated giant cells in the CNS

26

How does myelin change the space constant, conduction velocity and time constant

- ↑ space constant
- ↑ conduction velocity
- ↓ time constant

27

What is the embryologic derivation of Schwann cells and oligodendrocytes

Oligodendrocytes → neuroectoderm

Schwann cells → neural crest

28

Oligodendroglia are injured in what disease processes

- MS
- Progressive multifocal leukoencephalopathy (PML)
- Leukodystrophies

29

Free nerve endings

- C → slow, unmyelinated fibers
- A-delta → fast, myelinated fibers
- All skin, epidermis, some viscera
- Pain, temperature

30

Meissner corpuscles

- Large, myelinated fibers; adapt quickly
- Glabrous (hairless) skin
- Dynamic, fine/light tough, position sense

31

Pacinian corpuscles

- Large myelinated fibers; adapt quickly
- Deep skin layers, ligaments, joints
- Vibration, pressure

32

Merkel discs

- Large, myelinated fibers; adapt slowly
- Finger tips, superficial skin
- Pressure, deep static touch (eg shapes, edges)

33

Ruffini corpuscles

- Dendritic endings with capsule; adapt slowly
- Fingertips, joints
- Pressure, slippage of objects along surface of skin, joint angle change

34

What must be rejoined in microsurgery for limb reattachment

Perineurium

35

Epineurium

Dense connective tissue that surrounds entire nerve (fascicles and BLOOD VESSELS)

36

Location of acetylcholine synthesis

Basal nucleus of Meynert

37

Location of dopamine synthesis

Ventral tegmentum, SNpc

38

Location of GABA synthesis

Nucleus accumbens

39

Location of norepinephrine synthesis

Locus ceruleus

40

Location of serotonin synthesis

Raphe nucleus

41

Neurotransmitters in anxiety

- ↓ GABA
- ↑ norepinephrine
- ↓ serotonin

42

Neurotransmitters in depression

- ↓ dopamine
- ↓ norepinephrine
- ↓ serotonin

43

Neurotransmitters in schizophrenia

↑ dopamine

44

Neurotransmitters in Alzheimer disease

- ↓ acetylcholine
- ↑ glutamate

45

Neurotransmitters in Huntington disease

- ↓ acetylcholine
- ↑ dopamine
- ↓ GABA

46

Neurotransmitters in Parkinson disease

- ↑ acetylcholine
- ↓ dopamine
- ↑ serotonin

47

Blood-brain barrier formed by what 3 structures

- Tight junctions between nonfenestrated capillary endothelial cells
- Basement membrane
- Astrocyte foot processes

48

How do glucose and amino acids cross the BBB

Slowly by carrier mediated transport mechanisms

49

What kinds of substances cross the BBB rapidly via diffusion

Nonpolar/ lipid-soluble substances

50

Vasogenic edema

Infarction and/or neoplasm destroys endothelial cell tight junctions causing vasogenic edema

51

What is the hypothalamus responsible for

- Thirst and water balance
- Adenohypophysis control (regulates anterior pituitary)
- Neurohypophysis releases hormones hormones produced in the hypothalamus
- Hunger
- Autonomic regulation
- Temperature regulation
- Sexual urges

"TAN HATS"

52

What are input areas of the hypothalamus

- Organum vasculosum of the lamina terminalis (OVLT) → senses changes in osmolarity
- Area postrema (found in medulla) → responds to emetics

53

Lateral area of hypothalamus

- Hunger
- Destruction → anorexia, failure to thrive (infants)
- Stimulated by ghrelin
- Inhibited by leptin

54

Ventromedial area of hypothalamus

- Satiety
- Destruction (eg craniopharyngioma) → hyperphagia
- Stimulated by leptin

55

Anterior hypothalamus

- Cooling
- Parasympathetic

56

Posterior hypothalamus

- Heating
- Sympathetic

57

Suprachiasmatic nucleus

Circadian rhythm

58

Sleep physiology

- Circadian rhythm controls nocturnal release of ACTH, prolactin, melatonin, norepinephrine
- SCN → norepinephrine release → pineal gland → melatonin
- SCN is regulated by environment

59

Extraocular movements during REM sleep are due to

Activity of PPRF (paramedian pontine reticular formation/ conjugate gaze center)

60

Increase in what neurotransmitter occurs during REM sleep

Acetylcholine

61

What drugs are associated with ↓ REM sleep

- Alcohol, benzodiazepines, and barbiturates → ↓ REM sleep, ↓ delta wave sleep
- Norepinephrine → ↓ REM sleep

62

In which stage of sleep do bruxisms occur

N2

63

In what stage of sleep do night terrors, sleepwalking and bedwetting occur

N3

64

Ventral posterolateral nucleus of thalamus

- Input from spinothalamic and dorsal columns/medial lemniscus
- Senses pain, temperature, touch, vibration and propioception
- Destination is primary somatosensory cortex

65

Ventral posteromedial nucleus of thalamus

- Input from trigeminal and gustatory pathway
- Senses face sensation and taste
- Destination is primary somatosensory cortex

"Makeup goes of the face"

66

Lateral geniculate nucleus of thalamus

- Input from CN II
- Vision
- Destination is calacrine sulcus

"Lateral = light"

67

Medial geniculate nucleus of thalamus

- Input from superior olive and inferior colliculus of tectum
- Hearing
- Destination is auditory cortex of temporal lobe

"Medial = music"

68

Ventral lateral nucleus of thalamus

- Input from basal ganglia and cerebellum
- Motor
- Destination is motor cortex

69

Limbic system

- Collection of neural structures involved in emotion, long-term memory, olfaction, behavior modification, ANS function
- Structures include hippocampus, amygdala, fornix, mammillary bodies, cingulate gyrus
- Responsible for "Feeding, Fleeing, Fighting, Feeling and Fucking"

70

Dopaminergic pathways

- Mesocortical
- Mesolimbic
- Nigrostriatal
- Tuberoinfundibular

71

Mesocortical dopaminergic pathway

- ↓ activity → "negative" symptoms (eg flat affect, limited speech)
- Antipsychotic drugs have limited effect

72

Mesolimbic dopaminergic pathway

- ↑ activity → "positive" symptoms (eg delusions, hallucinations)
- Primary therapeutic target of antipsychotic drugs → ↓ positive symptoms (eg schizophrenia)

73

Nigrostriatal dopaminergic pathway

- ↓ activity → extrapyramidal symptoms (eg dystonia, akathisia, parkinsonism, tardive dyskinesia)
- Major dopaminergic pathway in brain
- Significantly affected by movement disorders

74

Tuberoinfundibular dopaminergic pathway

- ↓ activity → ↑ prolacting → ↓ libido, sexual dysfunction, galactorrhea, gynecomastia (in men)

75

Input to cerebellum

- Contralateral cortex via middle cerebellar peduncle
- Ipsilateral propioceptive information via inferior cerebellar peduncle from spinal cord

76

Output from cerebellum

- Sends information to contralateral cortex to modulate movement
- Output nerves: Purkinje cells → deep nuclei of cerebellum → contralateral cortex via superior cerebellar peduncle
- Deep nuclei (lateral to medial): dentate → emboliform → globose → fastigial ("Don't Eat Greasy Foods")

77

Lateral lesions to cerebellum

- Affect voluntary movement of extremities
- When injured, propensity to fall toward injured (ipsilateral) side

78

Medial lesions to cerebellum

- Involvement of midline structures (vermal cortex, fastigial nuclei) and/or flocculonodular lobe → truncal ataxia (wide based cerebelar gait), nystagmus, head tilting
- Generally result in bilateral motor deficits affecting axial and proximal limb musculature

79

Excitatory pathway

Cortical inputs stimulate the striatum, stimulating the release of GABA, which inhibits GABA release from the GPi, disinhibiting the thalamus via the GPi (↑ motion)

80

Inhibitory pathway

Cortical inputs stimulate the striatum, releasing GABA that disinhibits STN via GPe inhibition and STN stimulates GPi to inhibit the thalamus (↓ motion)

81

Compare D1 and D2

D1 → stimulates the excitatory pathway
D2 → inhibiting the inhibitory pathway (↑ motion)

82

Athetosis

- Slow, writing movements; especially seen in fingers
- Lesion of basal ganglia (eg Huntington)

83

Chorea

- Sudden, jerky, purposeless movements
- Lesion of basal ganglia (eg Huntington)

84

Dystonia

- Sustained, involuntary muscle contractions
- Writer's cramp; blepharospasm (sustained eyelid twitch)

85

Essential tremor

- High-frequency tremor with sustained posture (eg outstretched arms)
- Worsened with movement or when anxious
- Often familial
- Patients often self-medicate with alcohol, which ↓ tremor amplitude
- Treatment: nonselective β blockers (eg propanolol), primidone

86

Hemiballismus

- Sudden, wild flailing of 1 arm +/- ipsilateral leg
- Lesion to CONTRALATERAL subthalamic nucleus (eg lacunar stroke)

87

Intention tremor

- Slow, zigzag motion when pointing/extending toward a target
- Cerebellar dysfunction

88

Myoclonus

- Sudden, brief, uncontrolled muscle contraction
- Jerks
- Hiccups
- Common in metabolic abnormalities such as renal or liver failure

89

Resting tremor

- Uncontrolled movement of distal appendages (most noticeable in hands)
- Tremor alleviated by intentional movement
- Parkinson disease ("pill-rolling tremor")

90

How to treat essential tremor

Nonselective β blockers (eg propanolol) or primidone

91

How does neuronal death occur in Huntington disease

Neuronal death via NMDA-R binding and glutamate excitotoxicity

92

Compare aphasia and dysarthria

Aphasia → higher-order language deficit (inability to understand/ speak/ read/ write)

Dysarthria → motor inability to speak (movement deficit)

93

Conduction apahsia

- Fluent speech
- Intact comprehension
- Impaired repetition
- Can be caused by damage to arcuate fasciculus

94

Global aphasia

- Nonfluent speech
- Impaired comprehension
- Impaired repetition
- Damage to arcuate fasciculus, Broca and Wernicke area

95

Transcortical motor aphasia

- Nonfluent speech
- Intact comprehension
- Intact repetition
- Affects frontal lobe around Broca area, but Broca area is spared

96

Transcortical sensory aphasia

- Fluent speech
- Impaired comprehension
- Intact repetition
- Affects temporal lobe around Wernicke area, but Wernicke area is spared

97

Transcortical aphasia, mixed

- Nonfluent speech
- Impaired comprehension
- Intact repitition
- Broca and Wernicke area and arcuate fasciculus remain intact
- Surrounding watershed areas affected

98

Lesion to amygdala (bilateral)

- Kluver-Bucy syndrome → disinhibited behavior (eg hyperphagia, hypersexuality, hyperorality)
- Associated with HSV1 encephalitis

99

Lesion to frontal lobe

- Disinhibition and deficits in concentration, orientation, judgement
- May have reemergence of primitive reflexes

100

Lesion to nondominant parietal cortex

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

101

Lesion to dominant parietal cortex

- Agraphia
- Acalculia
- Finger agnosia
- Left-right disorientation
- Gerstmann syndrome → ability to read and speak is intact, results from damage to visual association cortex (located in angular gyrus)

102

Lesion to reticular activating system (midbrain)

Reduced levels of arousal and wakefulness (eg coma)

103

Lesion to mamillary bodies (bilateral)

- Werncke-Korsakoff syndrome → confusion, ophthalmoplegia, ataxia; memory loss (anterograde > retrograde amnesia), confabulation, personality changes
- Associated with thiamine (B1) deficiency and excessive alcohol use
- Can be precipitated by giving glucose without B1 to a B1 deficient patient
- Wernicke problems come in a CAN of beer → confusion, ataxia, nystagmus

104

Lesion to basal ganglia

- May result in a tremor at rest, chorea, athetosis
- Parkinson disease
- Huntington disease

105

Lesion to cerebellar hemisphere

- Intention tremor
- Limb ataxia
- Loss of balance
- Damage to cerebellum → ipsilateral deficits
- Fall toward side of lesion
- Degeneration associated with chronic alcohol use

106

Lesion to cerebellar vermis

- Truncal ataxia
- Dysarthria

107

Lesion to subthalamic nucleus

Contralateral hemiballismus

108

Lesion to hippocampus (bilateral)

Anterograde amnesia → inability to make new memories

109

Compare lesion to paramedian pontine reticular formation and frontal eye fields

Paramedian pontine reticular formation → eyes look AWAY from side of lesion

Frontal eye fields → eyes look toward lesion

110

Cerebral perfusion relies on

- Pressure gradient between mean arterial pressure (MAP) and ICP
- ↓ BP or ↑ ICP → ↓ cerebral perfusion pressure (CPP)
- CPP = MAP - ICP
- If CPP = 0, there is no cerebral perfusion → brain death

111

Therapeutic hyperventilation

↓ pCO2 → vasoconstriction → ↓ cerebral blood flow → ↓ intracranial pressure (ICP)

May be used to treat acute cerebral edema (eg secondary to stroke) unreponsible to other interventions

112

Middle cerebral artery stroke

Areas of lesions:
- Motor and sensory cortices → upper limb and face
- Temporal lobe → Wernicke area
- Frontal lobe → Broca area

Symptoms:
- Contralateral paralysis and sensory loss → face and upper limb
- Aphasia if in dominant (usually left) hemisphere
- Hemineglect if lesion affects nondominant (usually right) side

113

Anterior cerebral artery stroke

Areas of lesions:
- Motor and sensory cortices → lower limb

Symptoms:
- Contralateral paralysis and sensory loss → lower limb

114

Lenticulostriate artery stroke

Areas of lesions:
- Striatum
- Internal capsule

Symptoms:
- Contralateral paralysis and/or sensory loss → face and body
- Absence of cortical signs (eg neglect, aphasia, visual field loss)

Common location of lacunar infarcts, secondary to unmanaged hypertension.

115

Anterior spinal artery stroke

Areas of lesions:
- Lateral corticospinal tract
- Medial lemniscus
- Caudal medulla → hypoglossal nerve

Symptoms:
- Contralateral paralysis → upper and lower limbs
- ↓ contralateral propioception
- Ipsilateral hypoglossal deviation (tongue deviates ipsilaterally)

MEDIAL MEDULLARY SYNDROME → caused by infarct of paramedian branches of ASA and/or vertebral arteries

116

Posterior inferior cerebellar artery stroke

Areas of lesions:
- Lateral medulla → vestibular nuclei, lateral spinothalamic tract, spinal trigeminal nucleus, nucleus ambiguus, sympathetic fibers, inferior cerebellar peduncle

Symptoms:
- Vomiting, vertigo, nystagmus
- ↓ pain and temperature sensation from ipsilateral face and contralateral body
- Dysphagia, hoarseness, ↓ gag reflex
- Ipsilateral Horner syndrome
- Ataxia, dymetria

NUCLEUS AMBIGUUS → effects are specific to PICA lesions

LATERAL MEDULLARY (WALLENBERG) SYNDROME

"Don't pick a (PICA) horse (hoarseness) that can't eat (dysphagia)"

117

Anterior inferior cerebellar artery stroke

Areas of lesions:
- Lateral pons → cranial nerve nuclei (vestibular nuclei, facial nerve nucleus, spinal trigeminal nucleus, cochlear nuclei), spinothalamic tract, corticospinal tract, sympathetic fibers
- Middle and inferior cerebellar peduncles

Symptoms:
- Vomiting, vertigo, nystagmus
- Paralysis of face, ↓ lacrimation, salivation, ↓ taste from anterior 2/3 of tongue
- Ipsilateral ↓ pain and temperature of face
- Contralateral ↓ pain and temperature of the body
- Ataxia, dysmetria

LATERAL PONTINE SYNDROME → facial nucleus effects are specific to AICA lesions

"Facial droop means AICA's pooped"

118

Basilar artery stroke

Areas of lesions:
- Pons, medulla, lower midbrain, corticospinal and corticobulbar tracts, ocular cranial nerve nuclei, paramedian pointine reticular formation

Symptoms:
- Preserved consciousness, eye movement, blinking
- Quadriplegia, loss of voluntary facial, mouth, and tongue movements

"LOCKED-IN SYNDROME"

119

Posterior cerebral artery stroke

Areas of lesions:
- Occipital cortex
- Visual cortex

Symptoms:
- Contralateral hemianopia with macular sparing

120

Charcot-Bouchard microaneurysm

- Common
- Associated with chronic hypertension
- Affects small vessels (eg in basal ganglia, thalamus)
- Not seen on angiogram

121

Posterior communicating artery saccular aneurysm

- Compression may cause ipsilateral CN III palsy → mydriasis ("blown pupil")
- May also see ptosis, "down and out" eye

122

Central post-stroke pain syndrome

- Neuropathic pain due to thalamic lesions
- Initial parasthesias followed in weeks to months by allodynia (ordinarily painless stimuli cause pain) and dysesthesia
- Occurs in 10% of stroke patients

123

Intraparenchymal hemorrhage

- Most commonly caused by systemic hypertension
- Also seen with amyloid angiopathy (recurrent lobar hemorrhagic stroke in elderly), vasculitis, neoplasm
- May be secondary to reperfusion injury in ischemic stroke
- Typically occurs in basal ganglia and internal capsule (Charcot-Bouchard aneurysm of lenticulostriate vessels), but can be lobar

124

Areas most vulnerable to ischemia

- Hippocampus
- Neocortex
- Cerebellum
- Watershed areas

125

Dural venous sinuses

- Large venous channels that run through the dura
- Drain blood from cerebral veins and receive CSF from arachnoid granulations
- Empty into internal jugular vein

126

Venous sinus thrombosis

- Presents with sign/symptoms of ↑ ICP (eg headache, seizures, focal neurologic deficits)
- May lead to venous hemorrhage
- Associated with hypercoaguable states (eg pregnancy, OCP use, factor V Leiden)

127

Most common locations of vertebral disc herniation

L4-L5 or L5-S1

128

Where does the spinal cord end

Lower border of L1-L2 vertebrae

129

Where are lumbar punctures performed

Between L3-L4 or L4-L5

130

Where does the subarachnoid space end

S2

131

Dorsal column

- Ascending
- Pressure, vibration, fine touch, and propioception
- 1st order neuron: sensory nerve ending → cell body in DRG → enters spinal cord, ascends ipsilaterally in dorsal column
- Synapse 1: ipsilateral nucleus cuneatus or gracilis (medulla)
- 2nd order neuron: decussates in medulla → ascends contralaterally in medial lemniscus
- Synapse 2: VPL (thalamus)
- 3rd order neuron: sensory cortex

132

Spinothalamic tract

- Ascending
- Lateral: pain, temperature
- Anterior: crude touch, pressure
- 1st order neuron: sensory nerve ending (A-delta and C fibers) → cell body in DRG → enters spinal cord
- Synapse 1: ipsilateral gray matter (spinal cord)
- 2nd order neuron: decussates at anterior white commissure → ascends contralaterally
- Synapse 2: VPL (thalamus)
- 3rd order neuron: sensory cortex

133

Lateral corticospinal tract

- Descending
- Voluntary movement of contralateral limbs
- 1st order neuron: UMN: cell body in primary motor cortex → descends ipsilaterally (through internal capsule), most fibers decussate at caudal medulla (pyramidal decussation) → descends contralaterally
- Synapse 1: cell body of anterior horn (spinal cord)
- 2nd order neuron: LMN: leaves spinal cord
- Synapse 2: NMJ

134

Poliomyelitis and Werdnig-Hoffmann disease

- Congenital degeneration of anterior horns of spinal cord
- LMN lesions only
- "Floppy baby" with marked hypotonia and tongue fasciculation
- Infantile type has median age of death of 7 months
- AR
- Poliomyelitis → asymmetric weakness
- Werdnig-Hoffmann disease → symmetric weakness

135

Amyotrophic lateral sclerosis

- Combined UMN and LMN deficits with no sensory or bowel/bladder deficits (due to loss of cortical and spinal cord motor neurons, respectively)
- Can be caused by defect in superoxide dismutase 1
- Commonly presents with asymmetric limb weakness (hands/feet), fasciculations, and eventual atrophy
- Treatment: riluzole

136

Complete occlusion of anterior spinal artery

- Spares dorsal columns and Lissauer tract
- Upper thoracic ASA territory is watershed area, as artery of Adamkiewicz supplies ASA below T8
- Obstruction of artery of Adamkiewicz can also result in an ASA syndrome with urinary and fecal incontinence and impaired motor function of the legs; sensory is often preserved

137

Tabes dorsalis

- Caused by tertiary syphilis
- Results from degeneration (demyelination) of dorsal columns and roots → progressive sensory ataxia (impaired propioception → poor coordination)
- Associated with Charcot joints, shooting pain, Argyll Robertson pupils
- Exam will demonstrate absence of DTRs and + Rhomberg sign

138

Syringomyelia

- Syrinx expands and damages anterior white commissure of spinothalamic tract (2nd order neurons) → bilateral loss of pain and temperature sensation in cape like distribution
- Seen with Chiari I malformation
- Can expand and affect other tracts

139

Vitamin B12 deficiency

- Subacute combined degeneration (SCD) → demyelination of Spinocerebellar tracts, lateral Corticospinal tracts and Dorsal columns
- Ataxic gait, paresthesia, impaired position/vibration sense

140

Where does poliovirus first replicate

Oropharynx and small intestine before spreading via bloodstream to CNS

141

Where is poliovirus recovered from

Stool or throat

142

Friedreich ataxia

- AR trinucleotide repeat (GAA) on chromosome 9 in gene that encodes frataxin (iron binding protein)
- Leads to impairement in mitochondrial functioning
- Degeneration of multiple spinal cord tracts → muscle weakness and loss of DTRs, vibratory sense, propioception
- Staggering gait, frequent falling, nystagmus, dysarthria, pes cavus, hammer toes, diabetes mellitus, hypertrophic cardiomyopathy (cause of death)
- Presents in childhood with kyphoscoliosis

"Friedreich is a fratastic brother: he's your favorite frat brother, always staggering and falling but has a sweet, big heart"

143

What is the most common cause of death in patients with Frederich ataxia

Hypertrophic cardiomyopathy

144

Brown-Sequard syndrome

- Hemisection of spinal cord
- Ipsilateral UMN lesions below the level of lesion (due to corticospinal tract damage)
- Ipsilateral loss of tactile, vibration, propioception sense below level of lesion (due to dorsal column damage → this is because decussation occurs at medulla)
- Contralateral pain and temperature loss below level of lesion (due to spinothalamic tract damage)
- Ipsilateral loss of all sensation at level of lesion
- Ipsilateral LMN signs at level of lesion
- If lesion occurs above T1, patient may present with ipsilateral Horner syndrome due to damage of oculosympathetic pathway

145

Galant reflex

Stroking along one side of the spine while the newborn is in ventral suspension (face down) causes lateral flexion of lower body toward stimulated side

146

Parinaud syndrome

Paralysis of conjugate vertical gaze due to lesion in superior colliculi (eg stroke, hydrocephalus, pinealoma)

147

Nucleus solitarius

- Visceral sensory information (eg taste, baroreceptors, gut distension)
- CN VII, IX, X

148

Nucleus ambiguus

- Motor innervation of pharynx, larynx, upper esophagus (eg swallowing, elevation)
- CN IX, X, XI (cranial portion)

149

Dorsal motor nucleus

- Sends autonomic (parasympathetic) fibers to heart, lungs, upper GI
- CN X

150

CN VII UMN lesion

- Destruction of motor cortex or connection between motor cortex and facial nucleus in pons → contralateral paralysis of lower muscles of facial expression
- Forehead is spared due to its bilateral UMN innervation

151

CN VII LMN lesion

Destruction of facial nucleus or CN VII anywhere along its course → ipsilateral paralysis of upper and lower muscles of facial expression, hyperacusis, loss of taste sensation to anterior tongue

152

Facial nerve palsy

- Clinical syndrome of peripheral CN VII (LMN) lesion
- Depending on lesion location and severity, may cause partial or complete loss of function
- When idiopathic (most common), called BELL PALSY
- May also be caused by: Lyme disease, herpes simplex, herpes zoster (Ramsay Hunt syndrome), sarcoidois, tumors, diabetes mellitus
- Treatment is corticosteroids, acyclovir
- Most patients have gradual recovery of function

153

Cavernous sinus syndrome

- Presents with variable opthalmoplegia, ↓ corneal sensation, Horner syndrome and occasional decreased maxillary sensation
- Secondary to pituitary tumor mass effect, carotid-cavernous fistula, or cavernous sinus thrombosis related to infection
- CN VI is most susceptible to injury

154

Cholesteatoma

- Overgrowth of desquamated keratin debris within the middle ear space
- May erode ossicles, mastoid air cells → conductive hearing loss

155

What produces aqueous humor

Produced by nonpigmented epithelium of ciliary body (↓ by β-blockers, α2-agonists, and carbonic anhydrase inhibitors)

156

Aqueous humor outflow

Trabecular outflow (90%): drainage through trabecular meshwork → canal of Schlemm → episcleral vasculature (↑ with M3 agonist)

Uveoscleral outflow (10%): drainage into uvea and sclera (↑ with prostaglandin agonists)

157

Open angle glaucoma

- Associated with ↑ age, African-American race, family history
- Painless, more common in US
- PRIMARY → cause unclear
- SECONDARY → blocked trabecular meshwork from WBCs (eg uveitis), RBCs (eg vitreous hemorrhage), retinal elements (eg retinal detachment)

158

Closed or narrow-angle glaucoma

- PRIMARY → enlargement or forward movement of lens against central iris (pupil margin) → obstruction of normal aqueous flow through pupil → fluid builds up behind iris, pushing peripheral iris against cornea and impeding flow through trabecular meshwork
- SECONDARY → hypoxia from retinal disease (eg diabetes mellitus, vein occlusion) induces vasoproliferation in iris that contracts angle
- CHRONIC CLOSURE → often asymptomatic with damage to optic nerve and peripheral vision
- ACUTE CLOSURE → true emergency; ↑ IOP pushes iris forward → angle closes abruptly; very painful red eye with vision loss, halos around lights, rock-hard eye, frontal headache → DO NOT GIVE EPINEPHRINE B/C OF MYDRIATIC EFFECT

159

Uveitis

- Inflammation of uvea, specific name based on location within affected eye
- Anterior uveitis → iritis
- Intermediated uveitis → pars planitis (part of ciliary body)
- Posterior uveitis → choriditis and/or retinitis
- May have hypopyon (accumulation of pus in anterior chamber) or conjunctival redness
- Associated with systemic inflammatory disorders (eg sarcoidosis, rheumatoid arthritis, juvenile idiopathic arthritis, HLA-B27 associated conditions)

160

Age related macular degeneration

- Degeneration of macula (central area of retina)
- Causes distortion (metamorphopsia) and eventual loss of central vision (scotomas)
- DRY (NONEXUDATIVE, > 80%) → deposition of yellowish extracellular material in and between Bruch membrane and retinal pigment epithelium ("drusen") with gradual ↓ in vision; prevent progression with multivitamin and antioxidant supplements
- WET (EXUDATIVE, 10-15%) → rapid loss of vision due to bleeding secondary to choroidal neovascularization; treat with anti-VEGF (eg ranibizumab)
- Bruch membrane is the innermost layer of the choroid

161

Diabetic retinopathy

- Retinal damage due to chronic hyperglycemia
- NONPROLIFERATIVE → damaged capillaries leak blood → lipids and fluid seep into retina → hemorrhages and macular edema; treat with blood sugar control
- PROLIFERATIVE → chronic hypoxia results in new blood vessel formation with resultant traction on retina; treat with peripheral retinal photocoagulation, surgery, anti-VEGF

162

Retinal vein occlusion

- Blockage of central or branch retinal vein due to compression from nearby arterial atherosclerosis
- Retinal hemorrhage and venous engorgement, edema in affected areas

163

Retinal detachment

- Separation of neurosensory layer of retina (photoreceptor layer with rods and cones) from outermost pigmented epithelium (normally shields excess light, supports retina) → degeneration of photoreceptors → vision loss
- May be secondary to retinal breaks, diabetic traction, inflammatory effusions
- Visualized on fundoscopy as crinkling retinal tissue and changes in vessel direction
- Breaks more common in patients with myopia and/or history of head trauma
- Often preceded by posterior vitreous detachment (flashes and floaters) and eventual monocular loss of vision

164

Retinitis pigmentosa

- Inherited retinal degeneration
- Painless, progressive vision loss beginning with night blindness (rods affected first)
- Bone spicule shaped deposits around macula

165

Retinitis

- Retinal edema and necrosis leading to scar
- Often viral (CMV, HSV, VZV) but can be bacterial or parasitic
- May be associated with immunosuppression

166

Meyer loop

- Inferior retina
- Loops around interior horn of lateral ventricle in the temporal lobe

167

Dorsal optic radiation

- Superior retina
- Takes the shortest path via internal capsule in the parietal lobe

168

Charcot triad of MS

- Scanning speech
- Intention tremor (also Incontinence and Internuclear ophthalmoplegia)
- Nystagmus

"SIN"

169

Treatment for acute inflammatory demyelinating polyradiculopathy

- Respiratory support is critical until recovery
- Plasmapheresis, IV immunoglobulins
- No role for steroids

170

Acute disseminated (postinfectious) encephalomyelitis

- Mutlifocal periventricular inflammation and demyelination after infection or vaccination
- Presents with rapidly progressive multifocal neurologic symptoms, altered mental status
- Autoimmune disease marked by sudden widespread inflammation of brain and spinal cord, destruction of white matter

171

Charcot-Marie-Tooth disease

- AKA hereditary motor and sensory neuropathy (HMSN)
- Group of progressive hereditary nerve disorders related to the defective production of protein involved in the structure and function of peripheral nerves or the myelin sheath
- AD
- Assoicated with foot deformities (pes cavus), lower extremity weakness and sensory deficits

172

Adrenoleukodystrophy

- X linked disorder typically affecting males
- Disrupts metabolism of very-long-chain-fatty acids → excessive buildup in nervous system, adrenal glands, testes
- Progressive disease that can lead to long-term coma/death and adrenal gland crisis

173

Partial (focal) seizures

- Affect single area of the brain
- Most commonly originate in medial temporal lobe
- Often preceded by seizure aura
- Can secondarily generalize
- TYPES → simple partial, complex partial
- SIMPLE PARTIAL → consciousness intact; motor, sensory, autonomic, psychic
- COMPLEX PARTIAL → impaired consciousness

174

Generalized seizures

- ABSENCE → petit mal, 3 Hz, no postictal confusion, blank stare
- MYOCLONIC → quick, repetitive jerks
- TONIC-CLONIC → grand mal, alternating stiffening and movement
- TONIC → stiffening
- ATONIC → "drop" seizures (falls to floor); commonly mistaken for fainting

175

Excruciating periorbital pain with lacrimation and rhinorrhea

Cluster headache

176

Cluster, tension and migraine localization

- Cluster → unilateral
- Tension → bilateral
- Migraine → unilateral

177

Peripheral vertigo

- More common
- Inner ear etiology (eg semicircular canal debris, vestibular nerve infection, Meniere disease [low frequency hearing loss])
- Positional testing → DELAYED horizontal nystagmus

178

Central vertigo

- Brain stem or cerebellar lesion (eg stroke affecting vestibular nuclei or posterior fossa tumor)
- Findings: directional change of nystagmus, skew deviation, diplopia, dysmetria
- Positional testing → IMMEDIATE nystagmus in any direction (may change directions)
- Focal neurologic findings

179

Encephalotrigeminal angiomatosis

- Sturge-Weber syndrome
- Congenital, non-inherited (somatic) developmental anomaly of neural crest derivatives due to activating mutation of GNAQ gene
- Affects small (capillary-sized) blood vessels → port-wine stain of the face (nevus flammeus, a non-neoplastic "birth mark" in CN V1/V2 distribution)
- Ipsilateral leptomeningeal angioma → seizures/epilepsy
- Intellectual disability
- Episcleral hemangioma → ↑ IOP → early-onset glaucoma

- STURGE-Weber → Sporadic, port-wine Stain, Tram track calcifications (opposing gyri), Unilateral, Retardation, Glaucoma, GNAQ gene, Epilepsy

180

"Pseudopalisading" pleomorphic tumor cells that border central areas of necrosis and hemorrhage

Glioblastoma multiforme (grade IV astrocytoma)

181

Can produce EPO and cause secondary polycythemia

Hemangioblastoma → most often cerebellar

182

Chicken-wire capillary pattern

Oligodendroglioma

183

Cystic + solid gross appearance

Pilocytic astrocytoma

184

Can compress 4th ventricle and cause noncommunicating hydrocephalus

Medulloblastoma

185

Drop metastases to spinal cord

Medulloblastoma

186

Rod shaped blepharoplasts (basal ciliary bodies) found near nucleus

Ependymoma

187

Cholesterol crystals found in "motor oil" like fluid within tumor

Craniopharyngioma

188

β-hCG production

Pinealoma

189

Pinealoma

- Tumor of pineal gland
- Can cause Parinaud gland (compression of tectum → vertical gaze palsy)
- Obstructive hydrocephalus (compression of cerebral aqueduct)
- Precocious puberty in males (β-hCG production)
- Histologically similar to germ cell tumors (eg testicular seminoma)

190

Cingulate (subfalcine) herniation under falx cerebri

Can compress anterior cerebral artery

191

Downward transtentorial (central) herniation

- Caudal displacement of brain stem → rupture of paramedian basilar artery branches → Duret hemorrhages
- Usually fatal

192

Uncal herniation

- Uncus = medial temporal lobe
- Compresses ipsilateral CN III (blow pupil, "down and out" gaze, ipsilateral PCA (contralateral homonymous hemianopiawith macular sparing), contralateral crus cerebri at the Kernohan notch (ipsilateral paresis; a "false localization sign")

193

Cerebellar tonsillar herniation into the foramen magnum

Coma and death results when these herniations compress the brain stem