Epilepsies with diffuse slow spikes and waves of late onset.

26 adult epileptic patients with diffuse slow spikes and waves and start of seizures after the age of 6 years were analyzed. The seizure spectrum encompasses generalized and focal seizures. The occurrence of several types of seizures is the rule. Epileptic drop attacks are most characteristic. Atonic, tonic and myoclonic features may be present in this type of seizure. Neurological and mental deficits are common. Compared with Lennox-Gastaut syndrome of children, the degree of intellectual impairment is relatively mild. As to the etiology a primary and a secondary group can be distinguished. Genetic predisposition seems to play a crucial role in the primary group.