True myoclonic epilepsy in childhood.

Abstract

True myoclonic epilepsy is a rare but clear-cut form of epilepsy in childhood, with its own characteristic clinical and eeg features. Fourteen cases are described and contrasted with other forms of childhood epilepsy, in particular with the infantile spasms syndrome. Attacks consisted of a sudden, severe, and momentary muscular contraction resulting in a sudden jerk forwards or backwards of head and body and often an associated jerk of the arms. Attacks frequently caused injury by a violent fall or by striking a nearby object with head or limbs, but consciousness was seldom lost. The average age of onset was 3-1/2 years. In 9 children the onset of myoclonic attacks was preceded by other forms of fit. A family history of epilepsy was unusual, and abnormal neurological signs were found in only 2 children. Serial eeg recordings showed atypical spike and wave discharges, often with polyspikes 3 children showed photic sensitivity. The epilepsy was resistant to drug therapy but showed a tendency to improve spontaneously over the years. Although some degree of mental retardation occurred in 6 children, this was not severe enough to render them ineducable, and 8 out of 14 children were attending normal schools.