A comparison between one and three years of treatment in uncomplicated childhood epilepsy: A prospective study .2. The EEG as predictor of outcome after withdrawal of treatment

Purpose: We wished to evaluate the prognostic usefulness of various EEG parameters with respect to omission rates after discontinuation of antiepileptic drug (AED) therapy in children treated for epileptic seizures. Methods: Two hundred forty-four children with uncomplicated epileptic seizures were randomized to either 1 or 3 years of treatment with AEDs. The treatment was then discontinued in patients who had been seizure-free during the last 6 months of their allotted rime of treatment (n = 154). After treatment discontinuation, the children were followed for at least 2 years. EEG recordings were performed before treatment was initiated and at regular intervals during treatment. Results: The overall relapse rate was 37%. In many children, the amount of epileptiform activity varied considerably between subsequent recordings made during the treatment. The remission rate was slightly higher for children whose last recordings before AED discontinuation were free of epileptiform activity as compared with children in whom such activity was present. However, children who had irregular generalized spike-wave (SW) activity in the recordings made before discontinuation of treatment had a clearly higher relapse rate (67%) both as compared with children without epileptiform activity (33%) and as compared with children with other types of epileptiform activity (33%) in their last EEG recordings before discontinuation. All children treated for only 1 year whose final EEGs displayed generalized irregular SW activity relapsed. Conclusions: We conclude that the presence of epileptiform activity does not in itself necessarily influence prognosis after discontinuation of treatment but that certain types of such activity signal a high risk of relapse.