Late onset of myoclonic epilepsy of Janz

Myoclonic epilepsy of Janz is an essentially benign disorder with excellent response to valproic acid. The onset of myoclonic seizures in a patient at the age of 47 years, with normal mental status and a normal neurological examination, is reported. The electroencephalogram showed typical 3- to 5-Hz polyspike and wave complexes, some associated with myoclonic jerks but without loss of consciousness. The patient responded well to divalproex sodium, which controlled her seizures. A discussion of the condition and a review of the literature are included.