Atypical benign partial epilepsy/pseudo-Lennox syndrome.

The purpose of this report is to describe the full clinical and electroencephalograpic spectrum of atypical benign partial epilepsy (ABPE) or pseudo-Lennox syndrome (PLS). We retrospectively analyzed the clinical and EEG data of 43 children with ABPE/PLS seen in our department during the last 25 years. Criteria for diagnosis of ABPE/PLS were the occurrence of generalized minor seizures as previously described for ABPE/PLS and the detection of focal sharp waves indistinguishable from those of rolandic epilepsy (RE) with generalization during slow sleep. Mental development prior to onset of epilepsy was retarded in 26% of patients. In 74%, age at onset of seizures ranged from 2-5 years of age. Atonic-astatic seizures, atypical absences, and more rarely, myoclonic seizures were the predominating seizure types in 67% of patients. Status of minor seizures occurred in 40%. One or several episodes of partial and secondarily generalized seizures were observed. Rolandic seizures occurred in 28%. The EEG was characterized by a normal or slightly slowed background activity and predominantly multi-focal sharp waves (88%) which were activated to a bioelectrical status in 56% during sleep. No tonic seizures and no fast > 10 Hz spike discharges were observed in any of the 1.291 EEG of the patients. Despite an often temporarily therapy-resistant course which led to use of steroids in 51% of patients, seizures had ceased in 84% and epileptic discharges had disappeared in 72% of patients at last follow-up. All patients older than age 15 were seizure-free. However, the rate of mentally handicapped patients had more than doubled from 26 to 56%. EEG which could be performed in 41 out of 56 siblings demonstrated shw in 40% of siblings in whom EEG were done at the age of maximum penetrance of sharp waves (3-10 years). ABPE/PLS overlaps broadly with RE, but also with electrical status epilepticus during sleep and Landau-Kleffner syndrome. Therefore, ABPE/PLS can be ranked alongside RE and other idiopathic partial epilepsies. The high incidence of sharp waves in siblings suggests that ABPE/PLS and RE have a common underlying genetic etiology.