SECRETS Neurology - Huntingtons & Myasthenia Gravis

Question 1

ddx chorea

Answer 1

huntingtons
sydenham's chorea
wilson's disease
cerebrovascular causes
senile-related

Question 2

meds that cause chorea

Answer 2

haloperidol = block dopa receptors –> tardive dyskinesia

L-dopa = choreoathetosis of face and distal extremities

Question 3

huntington inheritance

Answer 3

AD 100% penetrance
anticipation (earlier age in later generations)
trinucleotide repeat CAG in huntingtin gene on chr 4

Question 4

huntington sx

Answer 4

dementia, behavioral changes (aggression, depression), chorea

fhx

Question 5

huntington pathology

Answer 5

significant atrophy of basal ganglia (caudate nucleus)

Question 6

huntington pathophysiology

Answer 6

degradation of GABA neurons of indirect pathway in caudate nucleus

disinhibition of motor thalamus

Question 7

wilson’s disease & dx

Answer 7

abnormal copper accumulation

serum ceruloplasmin

Question 8

diplopia cranial nerves

Answer 8

CNIV = superior oblique
CNVI = lateral rectus
CNIII = all other EOMs

MLF

Question 9

edrophonium

Answer 9

short acting cholinesterase inhibitor

increase concentration of ACh in synaptic cleft to overcome deficiency in available ACh receptors

positive test = deficiency of ACh action at NMJ –> myasthenia gravis

Question 10

myasthenia gravis association

Answer 10

thymoma or thymic hyperplasia

Question 11

myasthenia gravis pathophysiology

Answer 11

automminue antibodies against postsynaptic nicotinic ACh receptor in skeletal muscle fibers

Question 12

myasthenia gravis sx

Answer 12

striated muscle weakness

diplopia
ptosis
dysphagia
proximal muscle weakness, worse with use

Question 13

myasthenia gravis tx

Answer 13

long acting cholinesterase inhibitor = pyridostigmine, neostigmine

Question 14

cholinesterase inhibitor toxicity

Answer 14

excessive cholinergic activity

diarrhea, miosis, bronchospasm, excessive urination, bradycardia, salivation, lacrimation, sweating (DUMBBELSS)

Question 15

nondepolarizing neuromuscular blockers

Answer 15

analogs/derivatives of curare
antagonize nicotinic ACh receptor

muscle relaxation in surgical anesthesia

Question 16

Lambert-Eaton pathophysiology & sx

Answer 16

autoimmune antibodies to voltage-gated Ca channels on presynaptic neurons –> insufficient ACh release

muscle weakness, & strength increases with effort (ACh accumulation)

Question 17

Lambert-Eaton association

Answer 17

paraneoplastic syndrome

small cell carcinoma of lung