Post-hypoxic myoclonus

(Redirected from Status myoclonicus)


  • Myoclonus (irregular muscle contractions) after hypoxic brain injury due to cardiac arrest
  • Acute: onset within 48h of injury
    • Post-hypoxic myoclonic status: acute myoclonus lasting >30min
      • Difficult to control, associated with poor prognosis
      • Occurs in 30-40% of comatose cardiac arrest survivors
  • Chronic: onset days-weeks after cardiac arrest in patients who regained consciousness (AKA Lance-Adams syndrome)

Clinical Features

  • Acute:
    • Recent (within 48h) hypoxic brain injury with neuronal necrosis
    • Abrupt onset of irregular muscle contractions, focal or generalized
  • Post-hypoxic status myoclonus
    • Onset usually within 12-24h of injury
    • Generalized, multifocal clonus
  • Chronic
    • Onset days-weeks after arrest
    • Awareness preserved
    • Typically intention myoclonus

Differential Diagnosis


  • EEG (r/o seizure)
  • Evaluate for alternative etiologies



See Also

External Links