Negative Myoclonus

  • Roongroj Bhidayasiri
  • Daniel Tarsy
Part of the Current Clinical Neurology book series (CCNEU)


Negative myoclonus refers to an abrupt involuntary movement caused by sudden, brief interruptions of muscle activity. Recently, the Task Force on Classification and Terminology of the International League against Epilepsy recognized negative myoclonus as a seizure type, defining it as an “interruption of tonic muscle activity for less than 500 ms without evidence of preceding myoclonia.” Clinically, negative myoclonus is classified into four types: asterixis, postural lapses, epileptic negative myoclonus, and physiologic negative myoclonus. Asterixis, which usually occurs in metabolic or toxic encephalopathies, is considered to be subcortical in origin but the cerebral cortex may be involved in some cases.

Supplementary material

Examination shows an irregular distal upper extremity tremor and sudden jerks involving the hands and fingers bilaterally. When he maintains his hands in an extended posture, the jerky involuntary movements worsen and resemble a flapping tremor. There is an action tremor during finger-nose testing.

Negative myoclonus.mp4 (MP4 20,491KB)


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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Roongroj Bhidayasiri
    • 1
    • 2
  • Daniel Tarsy
    • 3
  1. 1.Chulalongkorn Center of Excellence on Parkinson’s Disease and Related DisordersChulalongkorn University HospitalBangkokThailand
  2. 2.Department of NeurologyDavid Geffen School of Medicine at UCLALos AngelesUSA
  3. 3.Department of NeurologyHarvard Medical School Beth Israel Deaconess Medical CenterBostonUSA

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