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Neuromuscular junction disorders mimicking myopathy
Author(s) -
Mongiovi Phillip C.,
Elsheikh Bakri,
Lawson Victoria H.,
Kissel John T.,
Arnold W. David
Publication year - 2014
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.24300
Subject(s) - repetitive nerve stimulation , neuromuscular junction , myopathy , electromyography , medicine , myasthenia gravis , acetylcholine receptor , compound muscle action potential , muscle biopsy , motor unit , neuromuscular disease , neuroscience , physical medicine and rehabilitation , biopsy , psychology , electrophysiology , anatomy , receptor , disease
: Small‐amplitude, short‐duration motor unit action potentials are non‐specific findings seen in myopathies and neuromuscular junction (NMJ) disorders. NMJ studies (repetitive nerve stimulation and single‐fiber electromyography) can determine if such findings are related to NMJ abnormalities but are not considered routinely in atypical cases. Methods : Medical records of 338 patients with confirmed NMJ disorders were reviewed to identify cases with a clinical or electrodiagnostic impression of myopathy during initial evaluation. A history of muscle biopsy with findings that did not support a myopathic process was required for inclusion. Results : Four patients met the inclusion criteria. NMJ studies were abnormal in all cases. One patient had elevated acetylcholine receptor antibodies. Three patients were antibody negative: 2 demonstrated immunotherapy responsiveness, and 1 had a Rapsyn mutation. Conclusions : NMJ disorders may mimic myopathies, and NMJ studies should be performed to clarify so‐called “myopathic” electromyographic findings to avoid unnecessary testing and delayed diagnosis. Muscle Nerve 50 : 854–856, 2014