Neuromuscular Junction Disorders

Question 1

For information:

Acetylcholinesterase hydrolysed ACh into acetyl and choline. The choline is then taken up into vesicles.

Therefore…

Answer 1

Acetylcholinesterase inhibitors increase the concentration of acetylcholine. Because acetylcholine does not get broken down.

Question 2

What is lambert Eaton myasthenia syndrome ?

Strong association with what?

Answer 2

Antibodies to PRE-synaptic calcium channels leads to less vesicle release.

With small cell lung cancer.

Question 3

How do you differentiate lambert Eaton and myasthenia gravis?

Answer 3

Lambert Eaton = pre-synaptic

Myasthenia gravis = post-synaptic

Differentiating features = lambert Eaton improves with exercise, hyporeflexia.

Question 4

What are the 2 peaks of incidence for mysathenia gravis?

Answer 4

Females in 3rd decade.

Males in 6th or 7th decade.

Autoantibodies to nicotinic/acetylcholine receptors on post synaptic membrane

Question 5

Clinical features of mysathenia gravis?

Answer 5

Weakness that typically fluctuates throughout the day.

Extraocular weakness is the most common, facial weakness, bulbar weakness.

Limb weakness typically proximal.

Question 6

Treatment of mysathenia gravis?

Answer 6

Acetylcholinesterase inhibitors

Or

Thymectomy

Can also give steroids / azathioprine.

In an emergency, give a plasma exchange or immunoglobulin.

Question 7

Mysathenia Crisis?

Answer 7

Severe relapse resulting in weakness of respiratory muscles and difficulty breathing.

Management = ventilatory support or IV Ig.

Question 8

Muscle groups in myasthenia gravis tend to be affected in the following order:

Answer 8

1) Extraocular = double vision, ptosis.
2) Bulbar = dysphasia, difficulty chewing, dysarthria.
3) Face: drooping of facial muscles and snarled expression.

Normal sensation and reflexes
Normal muscle appearance and tone.

Question 9

Management of lambert Eaton syndrome?

Answer 9

3,4 diphenhydramine

IV Immunoglobulins.