Minimum Electromyographic Burst Duration in Healthy Controls: Implications for Electrodiagnosis in Movement Disorders

Abstract

Background Background: Electromyogram (EMG) burst duration can provide additional diagnostic information when investigating hyperkinetic movement disorders, particularly when a functional movement disorder is suspected. It is generally accepted that EMG bursts <50 milliseconds are pathological. Objective Objective: To reassess minimum physiological EMG burst duration. Methods Methods: Surface EMG was recorded from face, trunk, and limb muscles in controls (n = 60; ages 19-85). Participants were instructed to generate the briefest possible ballistic movements involving each muscle (40 repetitions) or, in muscles spanning joints, to generate rapid rhythmic alternating movements (20-30 seconds), or both. Results Results: We found no effect of age on EMG burst duration. However, EMG burst duration varied significantly between body regions. Rhythmic EMG bursts were shorter than ballistic bursts but only significantly so for lower limbs (P < 0.001). EMG bursts of duration <50 milliseconds were frequently observed, particularly in appendicular muscles. Conclusion Conclusion: We present normal reference data for minimum EMG burst duration, which may assist clinical interpretation when investigating hyperkinetic movement disorders.