Lambert-Eaton myasthenic syndrome

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Lam·bert-Ea·ton myasthenic syn·drome (LEMS),

(lam'bert ē'tŏn),
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, for example, 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.

Lambert-Eaton myasthenic syndrome

(lăm′bərt-ēt′n)
n.
An autoimmune disorder that affects neuromuscular transmission and is usually associated with lung cancer, characterized by weakness of muscles especially in the limbs.

Lambert-Eaton myasthenic syndrome

(lam'bert-et'on)
[Edward Howard Lambert, U.S. physiologist, 1915–2003; Lee McKendree Eaton, U.S. physician, 1905–1958]
An autoimmune syndrome in which weakness of the proximal muscles (e.g., around the shoulder and the hip girdle), diminished reflexes, and autonomic dysfunction are found. The syndrome is often associated with small cell carcinoma of the lung or other malignancies. Its cause is a unique antibody against presynaptic calcium channels.
Synonym: Eaton-Lambert syndrome