Myaesthenia Gravis

Question 1

what is the pathophysiology of myasthenia graves?

Answer 1

autoimmune condition where antibodies attack the nicotine acetylcholine receptors in the neuromuscular junction in muscle fibres

limits ability of acetylcholine to initiate muscle contraction

Question 2

how is myasthenia gravis managed?

Answer 2

steroids (acutely)
plasmapheresis if steroid refractory

acetylcholinerase inhibitors (i.e. pyridostigmine)

surgical thymectomy

Question 3

what investigations would you carry out for the diagnosis of suspected myasthenia gravis?

Answer 3

blood;

• serum acetylcholine receptor antibody
• muscle-specific tyrosine kinase antibody

Repetitive nerve stimulation 
CT chest (thymoma)
Spirometry

Question 4

what are the side effects of acetylcholinesterase inhibitors?

Answer 4

diarrhoea
salivation
lacrimation
urinary frequency

Question 5

describe the action of acetylcholinesterase inhibitors.

Answer 5

they inhibit the enzyme acetylcholinesterase which is required to breakdown excess acetylcholine in the synaptic cleft
by inhibiting acetylcholinesterase, more nicotinic acetylcholine receptors are activated at the neuromuscular junction