Eaton-Lambert syndrome
Pronunciation: EE-ton LAM-bert syndrome
Alternative name for Lambert-Eaton myasthenic syndrome. A presynaptic neuromuscular junction disorder often associated with malignancy, particularly lung cancer.
Full Definition
Eaton-Lambert syndrome, also known as Lambert-Eaton myasthenic syndrome (LEMS), is an autoimmune disorder affecting presynaptic voltage-gated calcium channels at the neuromuscular junction. Approximately 50-60% of cases are associated with underlying malignancy, most commonly small cell lung carcinoma. The syndrome is characterized by proximal muscle weakness that improves with sustained exercise, reduced or absent reflexes that may facilitate with exercise, and autonomic dysfunction including dry mouth and erectile dysfunction. Diagnosis is confirmed by demonstration of >100% facilitation of CMAP amplitude following 10 seconds of maximal voluntary contraction or high-frequency stimulation.
Usage
Usage note: Consider both terms acceptable. Always evaluate for underlying malignancy, particularly lung cancer.
In Context
- "The patient was diagnosed with Eaton-Lambert syndrome following detection of voltage-gated calcium channel antibodies and paraneoplastic screening." — Oncology consultation
- "Eaton-Lambert syndrome was suspected given the pattern of weakness improvement with exercise and associated autonomic symptoms." — Neuromuscular clinic note