Myoclonus Home A-Z Health Information Health Library A-Z Myoclonus Overview Myoclonus is a sudden shock-like involuntary movement, which can be sudden contraction of muscle (positive myoclonus) or a pause in muscle activity (negative myoclonus or asterixis). The following types of myoclonuses have been determined:Based on distributionGeneralizedFocalMultifocalSegmentalBased on clinical presentationSpontaneousActionReflex (auditory, visual, or to touch)Based on site of origin:Cortical myoclonus- myoclonic jerks triggered by movement or stimulus-sensitive. EEG may be diagnostic: cortical discharges time-locked to myoclonic jerks; giant cortical somatosensory evoked potentialsBrainstem myoclonus- bilateral synchronous jerking with adduction of arms, flexion of elbows, flexion of trunk and head. Stimulus-induced: tap nose, lip, or head or loud noiseSpinal cord- rhythmic, repetitive, bilateral, jerking one or two adjacent parts Causes Physiological- hypnic jerks and hiccupEpilepsy- focal epilepsy (Epilepsia partialis continua), myoclonic epilepsies-progressive myoclonic epilepsy (Unverricht–Lundborg disease)Encephalopathy: metabolic (liver, renal failure)Infections: prion diseases, HIV, SSPEPost-anoxicDrugs: tricyclics, L-dopaDegenerative conditions: Alzheimer’s disease, MSA, corticobasal degeneration, celiac diseaseHereditary: HD, mitochondrial disorders, myoclonic dystonia (DYT 11), storage disordersFocal lesions brain or spinal cord Risk factors Nervous system disorders such as multiple sclerosis, epilepsy, Parkinson's disease, Alzheimer's disease, or Creutzfeldt-Jakob diseaseBrain or spinal cord injuries, brain tumours, or strokesInfections such as meningitis or encephalitisProlonged oxygen deprivation to the brain (hypoxia)Family historyCertain medications like anticonvulsantsOther conditions such as kidney or liver failure, chemical or drug intoxication, metabolic disorders, or autoimmune inflammatory conditions Specialist to approach Neurologist Treatment Medical treatment is initiated per clinician’s evaluation and underlying cause