Neuro

Question 1

Herniation syndromes

• Cingulate
• Transtentorial (uncal)
• Tonsillar

Answer 1

• Cingulate: herniation under falx cerebri; can compress ACA
• Transtentorial (uncal): central/downward; caudal displacement of brainstem –> rupture of paramedian basilar artery branches/Duret hemorrhages. usually fatal. Can also compress PCA (contralat homonymous hemianopia w/ macular sparing). If medial temporal lobe involved: CN III palsy or ipsi hemiparesis
• Tonsillar: cerebellar tonsil into foramen magnum. Coma and death from brainstem compression (cardiopulm arrest). Seen w/ Chiari malformations

Question 2

Rule of 4’s (brainstem strokes) and consequences of cortical strokes

Answer 2

Brainstem strokes: diffuse (gross) motor sx

• 4 CNs above pons (1-4…but only 3 and 4 really matter), pons (5-8), and medulla (9-12)
• 4 CNs divide into 12 (motor, midline): 3, 4, 6, 12
• 4 CNs lateral, don’t divide into 12: 5, 7, 9, 11
• 4 Midline (Medial) columns: Motor nucleus (3, 4, 6, 12), Motor pathway (CST), MLF (ipsi intranuclear ophthalmoplegia), Medial lemniscus
• 4 lateral (Side) columns: Sympathetic (horner’s), Spinothalamic (contra pain/temp & sensory loss), Sensory of V (ipsi face), Spinocerebellar (ataxia)

Cortical strokes: focal motor sx

• ACA: leg (contralat hemiplegia LL); behavioral sx if bilat + incontinence, primitive reflexes
• MCA: face (if dominant hemisphere MCA: Broca/Wernicke aphasia possible)
• PCA: vision (or language, if dominant hemisphere involved); contralat hemianopia with macular sparing
• PCom: saccular aneurysms; CN III (down and out)
• ACom: saccular aneurysms; chiasm (bitemporal hemianopia)

Question 3

Innervation/deviation with injury to:

• tongue
• uvula
• lips
• jaw

Answer 3

Magic rule of 17:

• tongue (12 - “lick your wounds”) and jaw (V3) deviate toward lesion. 12 + 5 = 17
• uvula (10) and lips (7) deviate to opposite side of lesion. 10 + 7 = 17

Question 4

Contents of the cavernous sinus

Answer 4

"O TOM CAT"
from top to bottom:
- Oculomotor (3)
- Trochlear (4)
- Ophthalmic (V1)
- Maxillary (V2)
- internal Carotid (medial)
- Abducens (6) - lateral to internal carotid; in line with the T of trochlear from medial to latera

Question 5

Myasthenia gravis vs. Lambert-Eaton myasthenic syndrome

Answer 5

MG: autoantibodies to ACh receptor; ptosis, diplopia, weak facial/periocular/pelvic girdle muscles. Worsens w/ use and muscle doesn’t respond with repeated stimulation. Assoc w/ thymoma, thymic hyperplasia. Dx w/ edrophonium, Tx w/ pyridostigmine

LEMS: autoantibodies to presyn. Ca2+ channel; proximal weakness, dry mouth, impotence, Improves w/ use and muscle strength augmented w/ repeated stimulation. Assoc w/ SCLC

Question 6

Charcot-Marie-Tooth

Answer 6

AD demyelination of peripheral nerves (CMTA1 caused by PMP22 gene duplication most common)

• sensory and motor LL deficits
• kyphoscoliosis
• foot deformities (pes cavus, hammer toe)

Question 7

Complications of subarachnoid hemorrhage

Answer 7

• Vasospasm (4-12 days after): d/t impaired brain autoregulation. Causes cerebral ischemia –> new onset confusion or focal neuro deficit. Prevent/reduce w/ selective CCB (nimodipine)
• Rebleed (3-10 days after) –> ischemic infarct
• increased risk of communicating and/or obstructive hydrocephalus

Question 8

Hypothalamic nuclei:

• Lateral
• Ventromedial
• Anterior
• Posterior
• Suprachiasmatic
• Supraoptic, paraventricular
• Preoptic

Answer 8

• Lateral: hunger. injury makes you Lean
• Ventromedial: satiety. injury makes you Very Massive
• Anterior: cooling (A/C), PSNS.
• Posterior: heat, SNS. injury makes you a Poikilotherm –> cold-blooded
• Suprachiasmatic: circadian rhythm (you need sleep to be Super Charismatic)
• Supraoptic, paraventricular: ADH/oxytocin synthesis
• Preoptic: thermoregulation, sexual behav. Releases GnRH. Failure of GnRH-producing neurons to migrate from olfactory pit = Kallmann syndrome

Question 9

Areas damaged first in hypoxic-ischemic injury (global cerebral ischemia)

Answer 9

• Hippocampus first (pyramidal cells of hippocampus and neocortex)
• Purkinje cells of cerebellum

Question 10

Findings with Brown-Sequard syndrome

Answer 10

Hemisection of SC

• ipsi LMN signs at level of lesion, UMN below level of lesion (CST dmg) - ant horn (motor)
• ipsi loss of DCML below level of lesion (decussates above SC in medulla)
• contra loss of pain/temp/touch (spinothalamic tract - decussates in SC)
• if lesion above T1: ipsi Horner syndrome

Question 11

Kluver-Bucy syndrome

Answer 11

Damage to temporal lobe/amygdala resulting in disinhibited behavior (hyperphagia, hypersexuality, hyperorality); also visual agnosia, placidity, amnesia. Can be seen as a result of HSV-1 encephalitis or TBI