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Stimulated single‐fiber electromyography in lambert‐eaton myasthenic syndrome
Author(s) -
Chaudhry Vinay,
Watson Danny F.,
Bird Shawn J.,
Cornblath David R.
Publication year - 1991
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880141215
Subject(s) - lambert eaton myasthenic syndrome , neuromuscular transmission , repetitive nerve stimulation , myasthenia gravis , extensor digitorum communis , compound muscle action potential , electromyography , medicine , stimulation , neuromuscular junction , congenital myasthenic syndrome , anesthesia , electrophysiology , acetylcholine receptor , neuroscience , physical medicine and rehabilitation , psychology , receptor
Abstract The Lambert‐Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular transmission. Electrodiagnosis is confirmed by an increase in compound muscle action potential amplitude during high‐frequency repetitive nerve stimulation or following brief exercise. We describe the results of stimulated single‐fiber electromyography in 4 patients with disorders of neuromuscular transmission: LEMS (2), LEMS/myasthenia gravis (MG) overlap (1), and MG (1). Stimulated SFEMG was performed in the extensor digitorum communis muscle with axonal intramuscular suprathreshold stimulation at low and high rates. In all 4 patients, a rate dependence of jitter was found. In LEMS and LEMS/MG, jitter and blocking improved with high stimulation rates, as compared with the opposite effect in MG. We conclude that stimulated SFEMG is a valuable technique in the diagnosis of LEMS.