Myoclonic status in nonprogressive encephalopathies: an update.

Myoclonic status in nonprogressive encephalopathies (MSNE) is an epileptic syndrome in development, characterized by the early onset of continuous diffuse epileptiform abnormalities, accompanied by positive and/or negative phenomena correlated with transient and recurring motor, cognitive, or behavioral disturbances. Outcome of MSNE is poor and may determine progressive neurologic deterioration. MSNE is not easy to recognize and should be distinguished from progressive myoclonic epilepsies and other rarely reported infantile myoclonic epilepsies. The identification of MSNE may guide the diagnostic work-up, suggesting the presence of a genetic defect, such as Angelman syndrome, hypoxic-ischemic encephalopathy, or brain malformation.