• concentric needle electrode;
  • frontalis;
  • jitter;
  • single-fiber electromyography;
  • voluntary jitter

Introduction: Normative data for jitter parameters using a disposable concentric needle have been described in a few studies. Methods: Jitter, expressed as the mean consecutive difference (MCD), was measured in the frontalis muscle in 20 subjects by voluntary contraction. Results: Mean MCD for individual studies (20, Gaussian), all potentials (400, non-Gaussian), and 18th highest value (20, Gaussian) were 19.9 ± 2.9 μs, 19.9 ± 6.6 μs, and 26.9 ± 4.4 μs, respectively. Conclusion: The suggested upper normal limit for mean MCD is 26 μs and for outliers is 36 μs. Muscle Nerve 47:440-442, 2013