Myasthenia Gravis ☺️

Question 1

Epidemiology

Etiology and pathophysiology

Answer 1

Women
AB to Ach receptors at NMJ => muscle fatiguability

Linked to

• thymomas, thymic hyperplasia
• AI conditions (pernicious anemia, AI thyroid, RA, SLE)

Question 2

Presentation

Answer 2

Muscles become progressively weaker with use and improve with rest

• eyelid weakness => diplopia, ptosis
• proximal muscle weakness (face, neck, limbs)
• dysphagia

Question 3

Investigations

• blood, imaging
• bedside

Answer 3

Single fibre electromyography

CT thorax - rule out thymoma

CK - muscle problem or nerve problem

Autoantibodies - ACh rec, muscle specific tyrosine kinase AB

Sustained upgaze test => fatigueable

Icepack test => reduces Achestrase activity => reduced Ach breakdown, reduced ptosis
-rules out LEM

Question 4

Management

• Pharmacological
• Surgical
• myasthenic crisis

Answer 4

• long acting cholinesterase inhibitors - pyridostigmine
• prednisolone

-thymectomy

Crisis - resp muscles too weak to breathe
Plasmapheresis, IVIG