Similarities in Mechanisms and Treatments for Epileptic and Nonepileptic Myoclonus.

Myoclonus is a disordered movement that may be an ictal phenomenon or may be due to various injuries in brain and spinal cord motor structures. Many epileptic and nonepileptic myoclonic conditions are associated with abnormalities in inhibitory neurotransmission. gamma-Aminobutyric acid type A (GABA(A))-receptor antagonists may trigger myoclonus. Several antiepilepsy drugs (AEDs) effective against myoclonic seizures [valproic acid (VPA), clonazepam (CZP), levetiracetam (LEV)] enhance GABAergic neurotransmission and improve myoclonic movement disorders. Together these associations suggest links between episodic disorders involving synchronous cortical discharges (seizures) and hyperkinetic movement disorders.