Neurology 13 - Myasthenia Gravis

Question 1

define myasthenia gravis

Answer 1

autoimmune attack of the postsynaptic acetylcholine receptors

strong link to thymoma

Question 2

presentation of m gravis

Answer 2

very variable
worsens as day goes on
PROXIMAL muscles + head/neck muscles mainly
diplopia
ptosis
weak swallow
slurring

Question 3

examination of m gravis

Answer 3

more ptosis after repeated blinking
repeated arm abduction 20x then comparison of arms shows comparative weakness

check thymectomy scar

check FVC

Question 4

diagnosis of m gravis

Answer 4

ACh-R autoantibodies
MuSK autoantibodies

MRI of thymus

test of neostigmine responsiveness (cholinesterase inhibitor)

Question 5

treatment of myasthenia gravis

Answer 5

pyridostigmine / neostigmine
immunosuppresion
remove thymus
biologics if still resistant

Question 6

treatment of myasthenic crisis

Answer 6

triggered by another insult

acute worsening of symptoms

may lead to respiratory failure

need BIPAP, possibly ITU+intubation

give IVIG + plasma exchange if necessary

Question 7

define Lambert-Eaton myasthenic syndrome

Answer 7

similar set of symptoms as m gravis, but occurs due to small cell lung cancer secreting autoantibodies to VG calcium channels (presynapse)

Question 8

treatment of LE myasthenic syndrome

Answer 8

exclude lung cancer

amifampridine
immunosuppression
IVIG, plasma exchange