Myasthenia Gravis

Question 1

Most patients with myasthenia gravis have an antibody to what?

Answer 1

Antibodies to acetylcholine receptors

Question 2

Is myasthenia gravis more common in women or men?

Answer 2

women 2:1 men

Question 3

Main clinical features of myasthenia gravis

Answer 3

muscle fatigability
- extraocular muscle weakness
- diplopia, ptosis
- proximal muscle weakness
- dysphagia

Question 4

What other conditions are associated with myasthenia gravis?

Answer 4

thymomas (15%)

autoimmune disorders:
- pernicious anaemia
- autoimmune thyroid disorders
- rheumatoid
- SLE

Question 5

Investigations to confirm a diagnosis of myasthenia

Answer 5

• single fibre electromyography
• CT thorax to exclude thymoma
• CK normal
• Anti-ACh Ab
• anti-muscle-specific tyrosine kinase antibodies

Question 6

Management of myasthenia gravis

Answer 6

Acetylcholinesterase inhibitors:
- Pyridostigmine

Immunosuppression:
- prednisolone
- azathioprine
- ciclosporin
- mycophenolate mofetil

Surgery:
thymectomy

Question 7

Management of myasthenic crisis

Answer 7

plasmapheresis
intravenous immunoglobulins

Question 8

Drugs which can exacerbate myasthenia

Answer 8

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