Clinical Utility of Neurophysiologic Classification (and Declassification) of Myoclonus: a Cohort Study

Background Movement clinical neurophysiology studies can distinguish myoclonus, tremor, and other jerky movements, however there has been limited demonstration of their real-world clinical impact. Objective Investigate movement study utility in clarifying movement classification and guiding patient management. Methods Retrospective study of myoclonus-related movement studies. Results Of 262 patients referred for consideration of myoclonus, 105 (40%) had myoclonus, 156 (59%) had no myoclonus (the commonest alternative classifications were functional jerks and tremor), and 1 was uncertain. An additional 29 studies identified myoclonus without prior clinical suspicion. 119/134 (89%) myoclonus cases had a specific neurophysiologic subtype identified, most commonly cortical (64, 54%). Diagnostic differential narrowed in 60% of cases, and a new diagnosis was made in 42 (14%) patients. Medication changes were made in 151 patients (52%), with improvement in 35/51 (67%) with follow-up. Conclusions Movement studies effectively clarified movement classification and identified unsuspected myoclonus, leading to changes in diagnosis and management.