Flashcards in Exam 4 Myasthenia Gravis Deck (11):
Myasthenia Gravis is?
Autoimmune dis of myoneural jxn
Myasthenia Gravis pathophys?
Ab's attack acetylcholine receptors (AChR) on post gang membrane of NMJ
Thymus abn in most
Myasthenia Gravis basic defect?
↓ # of AChR on postsynap mm membrane
Postsynap folds flatten ->
↓ efficiency of transmission
(ACh released normally but fails to trigger mm APs)
Myasthenia Gravis presentation? (6)
Proximal Skeletal mm weak/fatigue
Eyelid and EOM weak
Weak chewing, speaking, swallow
Weak respiratory mm
Worse w/ activity, better w/ rest
Myasthenia Gravis tests? (4)
Repetitive mm activities = reproduce sxs
Tensilon Test = Anticholinesterase -> ↓ACh breakdown -> ↑stim of limited AChRs = improved mm strength
ACh receptor Ab test:
+ = diagnostic,
- result does not r/o
EMG = decremental response to stim
CT/MRI of thorax for thymoma
Lambert-Eaton Myasthenic Synd is?
Impaired presynap release of ACh
U from CA-caused immune response
↓ or no DTRs
Dry mouth, Impotence
Nerve stim = incremental response
Drug-induced Myasthenia U from?
MM testing = jerky release
EMG = normal
Tensilon Test = negative
Thyroid dysfxn and MG?
Hyper or hypo can produce mm weakness
Progressive External Ophthalmoplegia is?
Rare disorder of EOM w/ proximal mm weakness