Generalized paroxysmal fast activity: electroencephalographic and clinical features.

We reviewed electroencephalographic and clinical features of 20 patients with generalized paroxysmal fast activity (GPFA). All had seizure disorders and all but 3 had more than one seizure type. Mental retardation was present in 17 patients. In most cases no cause for the seizures could be found. GPFA occurred almost exclusively in sleep. Fifteen patients had clinical seizures associated with this activity; in 8 the seizures were tonic. Additional generalized epileptiform abnormalities were present in 18 patients, 10 of whom had slow spike and wave complexes. Only 4 patients had normal background activity.