Myoclonus may also be classified as follows: By its distribution: Focal, segmental (contiguous areas), multifocal (noncontiguous areas), or generalized By its site of origin: Cortical, subcortical, segmental, or peripheral By clinical presentation: Positive or negative By its etiology: Essential (primary), acquired, or idiopathic By its trigger: Sensory or spontaneous Myoclonus classified by site of origin is as follows: Cortical: Cortical myoclonus is associated with cerebral cortex damage or epilepsy.