Rarely present a problem: other forms may occur due to a nervous system disorder can occur infrequently or many times per minute, often myoclonus is one of several signs in a wide variety of nervous system disorders. Ms, parkinson"s, alzheimer"s, creutzfeldt-jakob, serotonin toxicity, huntington"s, epilepsy. Clinical presentation: reflex: triggered by somesthetic, visual, and auditory stimuli, action: affects both postural muscles and focal prime movers. May affect postural activity: spontaneous: focal, multifocal, or generalized. Cortical myoclonus: originates in the sensorimotor cortex; propagates via the corticospinal tract. Origin: focal lesion (tumor, trauma, stroke); focal epilepsy. Clinical features: spontaneous localized muscle jerks (sometimes with secondary generalization); may be triggered by an external stimulus or superimposed on a voluntary movement. Abnormal activity in sensorimotor cortex transmitted along the corticospinal pathway (20 ms delay for arms; 35 ms delay for legs). Somatosensory evoked potentials (seps) are increased in amplitude (giant seps: subcortical.