Extremity Myoclonus, Upper

Medical Condition:
Extremity Myoclonus, Upper

Involuntary shock-like contractions, irregular in rhythm and amplitude, followed by relaxation, of a muscle or a group of muscles. This condition may be a feature of some CENTRAL NERVOUS SYSTEMS DISEASES (e.g., EPILEPSY, MYOCLONIC). Nocturnal myoclonus may represent a normal physiologic event or occur as the principal feature of the NOCTURNAL MYOCLONUS SYNDROME. (From Adams et al., Principles of Neurology, 6th ed, pp102-3).