Repetitive nerve stimulation cutoff values for the diagnosis of myasthenia gravis

Alon Abraham, Majed Alabdali, Abdulla Alsulaiman, Ari Breiner, Carolina Barnett, Hans D. Katzberg, Leif E. Lovblom, Vera Bril*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Introduction: Repetitive nerve stimulation (RNS) showing ≥ 10% decrement is considered the cutoff for myasthenia gravis (MG), but this has never been validated. The objective of this study was to find an optimal validated cutoff value for decrement on RNS. Methods: We performed retrospective chart review of patients who had electrophysiological assessment for possible MG from 2013 to 2015. Results: A total of 122 patients with MG and 182 controls were identified. RNS sensitivities for generalized and ocular MG using the traditional ≥10% cutoff value were 46% and 15%, respectively, for frontalis recordings, and 35% and 19%, respectively, for nasalis recordings. Using a decrement cutoff value of 7% for frontalis and 8% for nasalis increased the sensitivities by 6–11%, with specificities of 95–96%. Conclusions: For RNS in facial muscles, we suggest a cutoff value of 7–8%, which increases test sensitivity by 6–11%, while preserving high specificity for the diagnosis of MG. Muscle Nerve, 2016 Muscle Nerve 55: 166–170, 2017.

Original languageEnglish
Pages (from-to)166-170
Number of pages5
JournalMuscle and Nerve
Issue number2
StatePublished - 1 Feb 2017
Externally publishedYes


  • myasthenia gravis
  • repetitive nerve stimulation
  • sensitivity
  • single fiber EMG
  • specificity


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