myasthenia + exacerbating drugs

Question 1

what conditions are assoc with myasthenia gravis

Answer 1

thymomas !!

other autoimmune - pernicious anaemia, rheumatoid, SLE

thymic hyperplasia

Question 2

myasthenia investigations

Answer 2

single fibre electromyography
antibodies to acetycholine receptors

CK = normal
CT thorax to exclude thymoma

Question 3

Tensilon test

Answer 3

for myasthenia
- IV edrophonium reduces muscle weakness temporarily

• not commonly used anymore to due risk of cardiac arrhytmia

Question 4

management of myasthenia

Answer 4

long-acting acetylcholinersterase inhibitors = pyridostigmine

immunosuppress (not started immed)
- steroids

thymectomy

Question 5

management of myasthenic crisis

Answer 5

plasmapheresis

IV immunoglobulins

Question 6

drugs that can exacerbate myasthenia

Answer 6

beta blockerss !!
penicillamine
lithium
phenytoin
quinidine, procainamide

Question 7

antibiotics that exacerbate myasthenia

Answer 7

gentamicin
macrolides - erythromycin, clarithromycin, azithromycin
quinolones - ciprofloxacin
tetracyclines