Myasthenia Gravis (MG)

Question 1

What are the signs and symptoms go myasthenia graves ?

Answer 1

extraoccular signs:
- ptosis
- diplopia

bulbar weakness:
- altered speech
- altered swallow

muscles weakness
- fatiguable (worse with time/use)
- proximal distribution
- SOB due to neuromuscular ventilatory weakness/failure

Question 2

What type of neurological condition is myasthenia gravis ?

Answer 2

neuromuscular junction (NMJ) disorder

Question 3

What is the pathophysiology of myasthenia gravis?

Answer 3

autoimmune condition

• antibodies are released by B cells that attach to nicotinic receptors on muscle cells
• blocks acetylcholine from binding at the NMJ
• inhibits muscle contraction = weakness

Question 4

What are the 2 main NMJ disorders ?

Answer 4

• myasthenia gravis
• lambert-eaton myasthenic syndrome

Question 5

What part of the NMJ is affected by
a) myasthenia gravis (MG) ?
b) lambert-eaton myasthenic syndrome (LEMS) ?

Answer 5

MG = nicotinic receptors on muscle

LEMS = Ca channels in neurone/synapse

Question 6

What is the most common age of onset for myasthenia gravis ?

Answer 6

women = 20/30s

men = 50/60s

Question 7

What is the treatment for myasthenia gravis ?

Answer 7

• acetylcholinesterase inhibitors (e.g neostigmine)
• immunosuppression
• surgical thymus removal (thymectomy)