Prolonged postictal encephalopathy.

Eleven patients (6 males, 5 females; ages 7.5 to 40 years, mean 27.8) had prolonged postictal confusion lasting from 4 to 10 days. During that time, the EEG showed a typical encephalopathic pattern. Comprehensive evaluation ruled out the possibility of metabolic, toxic, drug-related, or ongoing nonconvulsive status epilepticus. We have designated this syndrome as prolonged postictal encephalopathy (PPIE). Nine of 11 patients were mildly to borderline mentally retarded. Ten had previous episodes of status epilepticus. Nine of 11 had minimal structural abnormalities (mainly diffuse cortical atrophy). Nine patients had multiple recurrent episodes of PPIE. All episodes occurred following a cluster of seizures: in 8 patients after a cluster of generalized tonic-clonic seizures, in 2 after complex partial seizures, and in 1 patient after a cluster of atypical absence seizures. This series suggests that vulnerability to develop PPIE exists in patients with diffuse structural abnormalities, mild to borderline mental retardation, a history of status epilepticus, and a tendency of seizures to cluster.