Neurology: Disorders Of Neuromuscular Transmission

Question 1

Is juvenile myasthenia similar to adult autoimmune MG?

Answer 1

Yes

Question 2

What causes juvenile myasthenia?

Answer 2

Binding of antibodies to acetylcholine receptors on the postsynaptic membrane of the neuromuscular junction - reducing the number of functional receptors

Question 3

How does juvenile myasthenia typically present?

Answer 3

Typically after 10 y/o
Opthalmoplegia 
Ptosis (due to ocular muscles fatigue) 
Loss of facial expression 
Difficulty chewing 
Generalised, especially proximal weakness may be seen
Tiredness after little activity

Question 4

What is opthalmoplegia?

Answer 4

Paralysis of extra ocular eye muscles

Question 5

How is the diagnosis of juvenile myasthenia confirmed?

Answer 5

Identifying acetylcholine receptor antibodies (60-80%)

Or more rarely: anti muscle specific kinase antibody (anti-MuSK)

Question 6

How is juvenile myasthenia managed?

Answer 6

Choline esterase inhibitors - pyridostigmine or neostigmine
Immunosuppressive therapy
Thymectomy if thymoma present
Plasma exchange if crisis

Question 7

What complications can occur with juvenile myasthenia?

Answer 7

Life threatening weakness of swallowing muscles or respiratory muscles