Myasthenia gravis

Question 1

presentation?

Answer 1

fluctuating and fatigable proximal muscle weakness ( worsens with repetitive motions and improves with rest): ocular ( diplopia, ptosis), bulbar ( dysphagia, dysarthria), respiratory ( myasthenic crisis).

Question 2

causes of exacerbation?

Answer 2

medications: antibiotics ( fluoroquinolones, aminoglycosides), neuromuscular blocking agents, cardiac meds ( beta blockers), magnesium sulfate, penicillamine.
physiologic stress: preg/childbirth, surgery ( especially thymectomy), infection.

Question 3

diagnosis?

Answer 3

ice pack test ( bedside), AChR-Ab highly specific ( acetylcholine receptor antibodies. CT scan of chest ( thymoma).

Question 4

treatment?

Answer 4

AChE inhibitors ( acetylcholinesterase) ex: pyridostigmine with or without immunotherapy ex: corticosteroids, azathioprine. 
thymectomy.

Question 5

myasthenic crisis precipitating factor?

Answer 5

infection or surgery.
preg or delivery.
tapering of immunosuppressive drugs.
meds ( aminoglycosides, beta blockers).

Question 6

M crisis signs and symptoms?

Answer 6

increased generalized and oropharyngeal weakness.
respiratory insufficiency/ dyspnea, severe respiratory muscle weakness leading to respiratory failure ( ex: accessory muscle use, hypoxemia, respiratory acidosis).

Question 7

treatment?

Answer 7

intubation for deteriorating respiratory status.

plasmapheresis or IVIG ( intravenous immunoglobulins) as well as corticosteroids.