Myoclonus is a brief muscle jerk caused by neuronal discharge. Myoclonus can be classified from various points of view such as (1) clinical presentaiton; (2) neurophysiological origin; and (3) etiology. Among them, classification on the basis of the underlying pathophysiology is most reasonable. However underlying pathophysiologies of myoclonus have not been well known, evolving electrophysiologic studies aid in making the diagnosis and privide insight into the pathophysiology of myoclonus. Furthermore these Can differentiate myoclonus from other movement disorders, and positive from negative myoclonus; more importantly, these reveal the origin of the discharges producing the jerks. Myoclonus could be classified into two broad groups, epiletic and nonepiletic, according to the different electrophysiologic findings. Epiletic myoclonus could also be subclassified into several groups according to the location of the presumed generators suspected by current electrophysiologic findings.
