Skip to main content
NeuroWiki
|

Neuromuscular

Myasthenia Gravis

Diagnosis, exacerbations, and myasthenic crisis

Myasthenia gravis (MG) causes fatigable weakness (eyes, bulbar, limbs). Myasthenic crisis requires ICU and often plasma exchange or IVIG.

1.Presentation

Fatigable ptosis, diplopia, dysarthria, dysphagia, proximal limbs. Worse with activity. Ocular or generalized. Thymoma in ~10–15%.[+]

2.Diagnosis

AChR antibodies (~85%). MuSK in some seronegative. Ice test, EMG (RNS decrement, SFEMG jitter) support.[+]

3.Myasthenic Crisis

Definition and Triggers

Respiratory or severe bulbar failure. Triggers: infection, surgery, drugs (e.g. aminoglycosides, Mg, beta-blockers), steroid taper, noncompliance.[+]

Management

ICU. FVC, NIF q2–4h. Intubate when FVC <20 ml/kg or NIF >−30. Hold Mestinon when intubated. Plasma exchange (PLEX) or IVIG — PLEX often works faster. Treat infection. Avoid precipitant drugs.[+]

Do not use magnesium, aminoglycosides, or fluoroquinolones in known MG. They can worsen weakness and precipitate crisis.

4.Chronic Treatment

Pyridostigmine. Immunosuppression (steroids, azathioprine, etc.). Thymectomy for thymoma; consider in AChR+ generalized. IVIG or PLEX for exacerbations.[+]

Tap underlined terms for details · Tap [+] to expand

NeuroWiki is a clinical reference. It does not substitute for your clinical judgment, current guidelines, or your institution's protocol. Verify before acting. Do not enter patient names, MRNs, or dates of birth. Privacy Policy