NCIt definition : A sudden, involuntary contraction of a muscle or group of muscles; these movements
may develop as a symptom of a number of neurological diseases, including epilepsy,
Parkinson's disease, Alzheimer's disease, or Creutzfeldt-Jacob disease.;
Alternative definition : NCI-GLOSS: A sudden, brief, strong contraction of a muscle or group of muscles that
cannot be controlled.;