The proposed investigation is a 9 month long trial with a 6 month double-blind placebo controlled trial of divalproex sodium (Depakote) and a 3 month open label extension phase. Prior to study entry, potential subjects will be evaluated with the standard PDN diagnostic/behavioral assessment (06-M-0065). Children meeting eligibility criteria will undergo an overnight EEG and those with frequent epileptiform discharges will be randomly assigned to receive divalproex sodium or placebo. Study drugs will be administered in a blinded fashion for 24 weeks with overnight EEG at 12 and 24 weeks. Biweekly then monthly visits with laboratory studies will monitor for behavioral improvement and for potential adverse effects. A 3 month open label extension phase follows.