Autoimmune disorder of the postsynaptic neuromuscular junction causing fatigable weakness, most often from anti-AChR antibodies.
Clinical features
- • Fatigable ptosis and diplopia
- • Bulbar weakness — dysphagia, nasal speech
- • Proximal limb weakness worse at end of day
Investigations
- • Anti-AChR then anti-MuSK antibodies
- • Repetitive nerve stimulation / single-fibre EMG
- • CT thorax for thymoma
- • Forced vital capacity for crisis risk
Management
- • Pyridostigmine 30–60 mg PO 4–6 hourly
- • Prednisolone with steroid-sparing azathioprine/mycophenolate
- • Crisis: IVIG 2 g/kg over 5 days or plasma exchange + ICU
- • Thymectomy if thymoma or generalised AChR-positive disease <50 y
Clinical pearls
- • Avoid aminoglycosides, macrolides, quinolones, magnesium and β-blockers
- • Monitor FVC, not SpO₂ — desaturation is a late sign
Related in WardRound
Educational — verify locally.
