Substantiating the Short Burst Duration in Cortical Myoclonus

Background Myoclonus is characterized by involuntary, shock-like movements, of which cortical (CM) and non-cortical myoclonus (NCM) are most common. Electrophysiology can help differentiate between these subtypes; however, the diagnostic value of several features is largely unknown. Objective This study aims to determine the diagnostic value of the burst duration in distinguishing CM and NCM. Methods We manually identified the burst duration of 8 patients with CM, confirmed by electromyography-electroencephalography registration or somatosensory-evoked potentials, and 19 patients with NCM, suspected due to a myoclonus-dystonia phenotype (MYC/DYT-SGCE positive and negative). Results The sensitivity and specificity were calculated to assess the diagnostic value. The burst duration of CM (31.1 ms) was significantly shorter than that of NCM (56.7 ms), with a sensitivity of 100% and a specificity of 89.5% at a threshold of 45.0 ms. A minimum of 10 randomly selected bursts were sufficient for reliable diagnostic accuracy. Conclusion The burst duration seems a valuable supportive diagnostic criterion for distinguishing CM and NCM. (c) 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.