title: Single-fiber EMG and clinical correlation in Lambert-Eaton myasthenic syndrome.
abstract: OBJECTIVE
  We analyzed 82 single-fiber EMG (SFEMG) tests in the extensor digitorum communis muscle in 30 Lambert-Eaton myasthenic syndrome (LEMS) patients to study the relationship between electrodiagnostic findings and clinical severity.
  
  
  METHODS
  The repetitive nerve stimulation test was performed in the abductor digiti quinti and flexor carpi ulnaris muscles. SFEMG was performed in the extensor digitorum communis muscle using the conventional method.
  
  
  RESULTS
  Fiber density was normal in all patients. Jitter was abnormal in all patients at the first evaluation regardless of clinical severity. The jitter was increasingly abnormal with worsening disease severity. Mean MCD correlated well with clinical and electrophysiological severity. In 5 potential pairs in 3 patients, MCD analysis in relation to firing rate showed improvement with increasing firing rates, which is consistent with presynaptic neuromuscular transmission disorders.
  
  
  CONCLUSIONS
  In all LEMS studies, SFEMG was abnormal on the first evaluation. The mean MCD correlated well with clinical and electrophysiological disease severity on the repetitive nerve stimulation test.
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA. shinjoh@charter.net
authors.forename: Shin J
authors.initials: SJ
authors.lastname: Oh
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohira
mesh_terms: D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D005542:Forearm; D006801:Humans; D015624:Lambert-Eaton Myasthenic Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D012720:Severity of Illness Index; D009435:Synaptic Transmission / Q000502:physiology*