Myoclonus- A Review

Myoclonus is a hyperkinetic movement disorder characterized by a sudden, brief, involuntary jerk. Positive myoclonus is caused by abrupt muscle contractions, while negative myoclonus by sudden cessation of ongoing muscular contractions. Myoclonus can be classified in various ways according to body distribution, relation to activity, neurophysiology, and etiology. The neurophysiological classification of myoclonus by means of electrophysiological tests is helpful in guiding the best therapeutic strategy. Given the diverse etiologies of myoclonus, a thorough history and detailed physical examination are key to the evaluation of myoclonus. These along with basic laboratory testing and neurophysiological studies help in narrowing down the clinical possibilities. Though symptomatic treatment is required in the majority of cases, treatment of the underlying etiology should be the primary aim whenever possible. Symptomatic treatment is often not satisfactory, and a combination of different drugs is often required to control the myoclonus. This review addresses the etiology, classification, clinical approach, and management of myoclonus.