Herniation syndromes
- Cingulate
- Transtentorial (uncal)
- Tonsillar
- 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
Rule of 4’s (brainstem strokes) and consequences of cortical strokes
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)
Innervation/deviation with injury to:
- tongue
- uvula
- lips
- jaw
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
Contents of the cavernous sinus
"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
Myasthenia gravis vs. Lambert-Eaton myasthenic syndrome
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
Charcot-Marie-Tooth
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)
Complications of subarachnoid hemorrhage
- 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
Hypothalamic nuclei:
- Lateral
- Ventromedial
- Anterior
- Posterior
- Suprachiasmatic
- Supraoptic, paraventricular
- Preoptic
- 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
Areas damaged first in hypoxic-ischemic injury (global cerebral ischemia)
- Hippocampus first (pyramidal cells of hippocampus and neocortex)
- Purkinje cells of cerebellum
Findings with Brown-Sequard syndrome
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
Kluver-Bucy syndrome
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
