Juvenile myoclonic epilepsy of Janz.

We studied 43 patients, aged 15 to 69 years, whose convulsive seizures were uncontrolled because the syndrome of juvenile myoclonic epilepsy was not recognized. Awakening myoclonic jerks appeared with tonic-clonic (18 patients), clonic-tonic-clonic (24 patients), and absence seizures (17 patients), with a mean age at onset of 13.6 years. Generalized seizures were present in relatives of 17 patients. All patients had diffuse 3 1/2- to 6-Hz multispike-wave complexes. Valproic acid stopped convulsions in 86% of patients. After being free of seizures for 2 years, withdrawal of valproic acid was followed by relapse of convulsions in 12 patients.