Rapid (<100 ms), brief, shock-like, jerky, movements, usually multifocal. Like asterixis, often occurs in a diffuse encephalopathy. Following cardiac arrest, diffuse cerebral hypoxia may produce multifocal myoclonus. Spinal cord injury can also cause myoclonus. Myoclonus occurs in normal individuals when waking up or falling asleep.

• Treatment, indicated only when function is impaired, consists of treating the underlying condition or removing an offending agent.
• Drug therapies include valproic acid (800-3000 mg/d), piracetam (8-20 g/d), clonazepam (2-15 mg/d), levetiracetam (1000-3000 mg/d), or primidone (500-1000 mg/d).