Pathoma 18.5

Question 1

Myasthenia gravis

Answer 1

autoantibodies against the postsynaptic achetylcholine receptor at the neuromuscular junction (so more in women)

Question 2

Clinical features of myasthenia gravis

Answer 2

muscle weakness that worsens with use and improves with rest - classically involves eyes leading to ptosis and diplopia

Question 3

What improves clinical symptoms of myasthenia gravis

Answer 3

anticholinesterase agents (need more Ach to compete with antibodies - you release less ach with each firing)

Question 4

What is myasthenia gravis associated with?

Answer 4

thymic hyperplasia or thymoma - thymectomy improves symptoms

Question 5

Lambert-Eaton syndrome

Answer 5

antibodies against presynaptic calcium channels of the neuromuscular junction

Question 6

What is associated with Lambert-Eaton syndrome?

Answer 6

paraneoplastic syndrome due to small cell carcinoma of the lung usually

Question 7

What are the clinical features of Lambert-Eaton syndrome?

Answer 7

proximal muscle weakness that IMPROVES with use - eyes are usually spared

Question 8

What improves Lambert-Eaton syndrome?

Answer 8

resection of cancer - anticholinesterase agents do NOT improve symtpoms

Question 9

What does Lambert-Eaton syndrome lead to?

Answer 9

impaired acetylcholine release = firing of presynaptic calcium channels is required for acetylcholine release