Concentric-needle single-fiber electromyography for the diagnosis of myasthenia gravis

Michael Benatar, Mustafa Hammad, Heidi Doss-Riney

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


The goal of this study was to estimate the accuracy of concentric-needle single-fiber electromyography (CN-SFEMG) for the diagnosis of myasthenia gravis (MG). A consecutive series of patients referred for CN-SFEMG was evaluated by an investigator blinded to the results of CN-SFEMG in order to determine the presence or absence of MG using an independent reference standard. Sensitivity, specificity, predictive values, and likelihood ratios were calculated. The study population included 51 patients (21 with MG). CN-SFEMG was normal in 34 patients (67%) and abnormal in 17 (33%). The sensitivity of CN-SFEMG for the diagnosis of MG was 0.67 and the specificity was 0.96. The positive likelihood ratio was 16.8 and the negative likelihood ratio was 0.34. The positive and negative predictive values were 0.93 and 0.76, respectively. These results indicate that CN-SFEMG showing abnormal jiggle is extremely useful for confirming the diagnosis of MG, but that CN-SFEMG showing normal jiggle has limited utility in excluding the diagnosis.

Original languageEnglish (US)
Pages (from-to)163-168
Number of pages6
JournalMuscle and Nerve
Issue number2
StatePublished - Aug 1 2006
Externally publishedYes


  • Concentric-needle SFEMG
  • Likelihood ratio
  • Myasthenia gravis
  • Sensitivity
  • Single-fiber electromyography
  • Specificity

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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