DR Medhat MRCP

Lambert-Eaton myasthenic syndrome
• Def : Autoimmune disease characterized by muscle weakness.
• Predisposing factors & pathogenesis :
- Is seen in association with small cell lung cancer, and to a lesser extent breast and
ovarian cancer.
- It may also occur independently as an autoimmune disorder.
- Lambert-Eaton myasthenic syndrome is caused by an antibody directed against presynaptic
voltage gated calcium channel in the peripheral nervous system
• Features :
Repeated muscle contractions lead to increased muscle strength* (in contrast to
myasthenia gravis)
Limb girdle weakness (affects lower limbs first)
Hyporeflexia
Autonomic symptoms: dry mouth, impotence, difficultly micturating
Ophthalmoplegia and ptosis not commonly a feature (unlike in myasthenia gravis)
• EMG
Incremental response to repetitive electrical stimulation
• Management:
1) Treatment of underlying cancer.
2) Immunosuppression, for example with prednisolone and/or azathioprine.
3) 3,4-diaminopyridine is currently being trialled**.
4) Intravenous immunoglobulin therapy and plasma exchange may be beneficial.
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