Childhood absence epilepsy and electroencephalographic focal abnormalities with or without clinical manifestations

We studied the electroclinical features and evolution in patients with childhood absence epilepsy (CAE) associated with electroencephalographic findings similar to those of benign focal epilepsies (BFE) with or without clinical manifestations compatible with these focal idiopathic syndromes.

Between June 1994 and June 2002, we found 203 (3.6%) patients with typical electroclinical features of CAE among 8285 children with epilepsy. From this population of 203, we found 30 cases (14.7%) that also showed focal abnormalities of BFE on the EEG. Seven of these 30 cases also had clinical manifestations of BFE that preceded the onset of the absences.

There were 20 (66.5%) boys and 10 (33.5%) girls. Age at onset of absences ranged from 2 to 10.5 years, with a mean age of 5.5 years. Of 30, 7 had focal clinical seizures as well. Three of seven had seizures characteristic of Panayiotopoulos syndrome (PS), and the other four had seizures compatible with childhood occipital epilepsy (COE) of Gastaut. The focal seizures started between 3 and 7 years of age. In all patients seizures were under control within 2-24 months (mean: 11 months) after onset. The focal discharges disappeared in 26 patients at a mean age of 8 years (range 4-13 years), 1 year after the typical absences had disappeared. In four patients the focal paroxysms are still present.

The association of two different idiopathic focal and generalized epilepsies in the same patient may be merely coincidental, but a close genetic relationship between both epileptic syndromes might be another hypothesis. Another explanation could be that our series of patients represent a subgroup of CAE.