Neurophysiology of positive and negative myoclonus (vol 107, pg 181, 1998)

Myoclonus is defined as a sudden, brief, jerky, shock-like, involuntary mov ement, arising from the central nervous system that can be caused by a musc ular contraction, i.e. positive myoclonus, or by an interruption of muscula r activity, i.e. negative myoclonus. Myoclonus can characterize a variety o f neurological disorders, and often both positive and negative myoclonus ca n coexist. In this paper, we outline some relevant clinical aspects and neu rophysiological features of the different types of myoclonus, with particul ar emphasis on the physiological findings. Indeed, since most myoclonus dep end on enhancement of neuronal activities which are inherently present in n ormal subjects, electrophysiological studies are useful for elucidating the underlying pathophysiological mechanisms and for establishing the correct diagnosis. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.