Myasthenia Gravis

Question 1

What is this describing?
Autoimmune disease mediated by autoantibodies to the nicotinic ACh receptor on the post-synaptic side of the neuro-muscular junction. B and T cells implicated.

Answer 1

Myasthenia gravis

Question 2

What is this a presentation of?
Slowly increasing or relapsing muscle fatigue, ptosis, diplopia, count to 50 voice fades, normal reflexes. Exacerbated by pregnancy, hypokalaemia, infection, emotion, exercise.

Answer 2

Myasthenia gravis

Question 3

What are the most common sites of fatigue in myasthenia gravis?

Answer 3

Extraocular (ptosis) > bulbar (chewing, swallowing) > face > neck

Question 4

How is suspected Myasthenia gravis investigated?

Answer 4

1. Anti-AChR +ve in 90%
2. EMG
3. CT to exclude thymoma
4. Ptosis improves by >2mm after ice application for >2 minutes.

Question 5

What is the treatment for Myasthenia gravis?

Answer 5

1. Anticholinesterase - pyridostigmine 60-120mg PO up to 6x daily.
2. treat relapses with prednisolone
3. Thymectomy may be beneficial in younger patients

Question 6

What is the acute crisis to be aware of in someone with Myasthenia gravis?

Answer 6

1. Myasthenic crisis

2. Life-threatening weakness of respiratory muscles during relapse

Question 7

What is the treatment for a myasthenic crisis?

Answer 7

1. Plasmapheresis or IVIg

2. Ventilatory support may be needed

Question 8

What is this describing?
Antibodies to voltage-gated calcium channels on the pre-synaptic membrane, associated with small cell lung cancer, gait difficulty before eye signs, weakness improves with exercise.

Answer 8

Lambert-Eaton