5.6 Myasthenia Gravis Flashcards
myasthenia gravis is caused by antibodies that block __________ receptor
cholinergic
myasthenia gravis onset peaks in 20s for _______ and in 50s for _______
women, men
15% of patients with myasthenia gravis also present with _________
thymoma
most common symptoms of MG are __________, and progress to generalized MG within ____ years
ocular, 3
most SPECIFIC test for MG, presence of antibodies is nearly diagnostic
acetylcholine receptor antibody test
inject ACh-esterase inhibitor, allows more acetylcholine in NMJ to compete, ptosis improves, good sensitivity and bad specificity
edrophonium test
depletion of acetylcholine and amplitude of action potentials decrease, painful
repetitive stimulation
most sensitive test for MG, single muscle fiber action potential, firing time of 2nd fiber in a motor unit later due to delay in NMJ transmission, jitter or blocked action potential
single fiber EMG
most specific test for MG?
acetylcholine receptor antibodies
most sensitive test for MG?
single fiber EMG
suppress immune system, high doses make them worse initially, use adjucant chemo like drugs to help with immunosuppression
corticosteroids
stops production of abnormal antibody, negative feedback
IVIG
mestinon 1st line, used prior to steroids, GI side effects treated with anticholinergics, lasts hours
pyridostigmine
remove antibodies, most effective, good for crisis or non-responsive to steroids
plasmapheresis
80% of patients have ______ abnormalities
thymus
