juvenile myoclonic epilepsy

n.
  1. A form of epilepsy that occurs in adolescents, usually upon awakening, and is characterized by jerks of the shoulder muscles and by seizures that have a clonic phase, followed by a tonic phase, then by a return to clonus.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.