Propriospinal myoclonus.

The concept of propriospinal myoclonus is briefly reviewed in this report. Myoclonus can be classified according to the site of the generator into cortical, subcortical but supraspinal, and spinal myoclonus. Propriospinal myoclonus is a special type of spinal myoclonus characterized by rhythmic or arrhythmic, spontaneous or sometimes stimulus-sensitive flexion or extension movements of the axial muscles of the body with or without spread to the limbs excluding the cranially innervated muscles. Neurophysiologic study shows a characteristic pattern of order of recruitment of electromyographic bursts which are initially noted in the midthoracic segments (myoclonic generator) followed by propagation up and down the spinal cord via slowly conducting (3-11 M/s) pathways, such as the propriospinal systems. The role of spinal cord in functioning as a stepping generator and in locomotion has been strengthened by this new concept of propriospinal myoclonus.