Myasthenia Gravis

Question 1

Symptomatic control myasthenia gravis

Answer 1

Pyridostigmine
Neostigmine, edrophonium

Question 1

WHat is myasthenia gravis

Answer 1

AI disorder - insufficient ACH functioning at NMJ - tiredness due to fatiguability

Question 2

How does pyridostigmine work

Answer 2

long-acting acetylcholinesterase inhibitor that reduces the breakdown of acetylcholine in the neuromuscular junction, temporarily improving symptoms of myasthenia gravis

Question 3

Features of myasthenia gravis

Answer 3

Fatiguability
extraocular muscle weakness: diplopia
proximal muscle weakness: face, neck, limb girdle
ptosis
dysphagia

Question 4

Associations with myasthenia gravis

Answer 4

Thymomas 15%
AI disorders- pernicious anaemia, AI thyroid, rheumatoid, SLE
Thymic hyperplasia

Question 5

Investigations for myasthenia gravis

Answer 5

Single fibre EMG - v sensitive
CT thorax - thymoma
Normal CK
Antibpdies to ACH - anti muscle specific tyrosine kinase receptors
Tensilon test - IV edrophonum redues muscle weakess - not used due to cardiac arrest riks

Question 6

Managing myasthenia crisis

Answer 6

Plasmapheresis
IV IG

Question 7

Management of myasthenia gravis eventually requiring

Answer 7

Prednisolone
May use azathioprine, cyclosporine, mycophenolate mofetil

Question 8

What diuretics can cause otoxicity

Answer 8

Loop diuretics

Question 9

Drugs exacerbating MG

Answer 9

penicillamine
quinidine, procainamide
beta-blockers
lithium
phenytoin
antibiotics: gentamicin, macrolides, quinolones, tetracyclines