Myoclonus

Myoclonus, one of the most common involuntary movement disorders, poses particular challenges for the treating physician. The evaluation of a patient with myoclonus depends completely on the clinical history and examination, supported when necessary by electrophysiology, neuroimaging and selected genetic and laboratory testing. The sudden, shock-like jerks which define myoclonus may be highly disabling, and when they persist, often require treatment.

In a paper published in this journal, we reviewed the published trials of antimyoclonic agents, and formulated a treatment algorithm based on the available evidence. In the current paper, we present our approach for evaluating patients with myoclonus, and suggest practical guidelines for treating patients based on the pre-2000 literature and on studies published in the last 2 years. The newer medications which are being used in management of myoclonus are levetiracetam and gamma-hydroxybutyric acid. Levetiracetam is especially useful for posthypoxic myoclonus and gamma-hydroxybutyric acid for alcohol-sensitive myoclonus. A combination of medications is often needed to obtain adequate control of symptoms. Botulinum toxin is also being introduced for focal myoclonus with encouraging results.

There are no approved medications for myoclonus, and most therapies are borrowed from the antiepileptic and psychiatric armamentarium. Nonetheless, there is a logic to the choice and dosing of antimyoclonic drugs, and we hope that by applying a few simple principles, neurologists will approach the care of these patients with confidence.