Lambert-Eaton myasthenic syndrome

Pronunciation: lam′bert ē′tŏn

Definition: a generalized disorder of neuromuscular transmission caused by a defect in the release of acetylcholine quanta from the presynaptic nerve terminals; often associated with small cell carcinoma of the lung, particularly in elderly men with a long history of cigarette smoking. In contrast to myasthenia gravis, weakness tends to affect solely axial muscles, girdle muscles, and less often the limb muscles; autonomic disturbances, dry mouth and impotence, are common; the deep tendon reflexes are unelicitable; on motor conduction studies, responses on initial stimulation are quite low in amplitude, but they show marked posttetanic facilitation after a few seconds of exercise. Lambert-Eaton syndrome is due to loss of voltage-sensitive calcium channels located on the presynaptic motor nerve terminal.

See: myasthenic syndrome

Synonym(s): carcinomatous myopathy, Eaton-Lambert syndrome, Lambert syndrome, Lambert-Eaton syndrome, myasthenic syndrome

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