Antiepileptic drugs and atypical evolution of idiopathic partial epilepsy

Six patients with classic benign epilepsy of childhood with centrotemporal spikes, treated with carbamazepine (four patients) or sodium valproate (two patients) evolved atypically because the epileptic disorder, diffusion of the electroencephalographic (EEG) discharges during wakefulness, and continuous spike-and-wave during slow sleep associated with severe neuropsychologic abnormalities worsened. These features appeared after a seizure-free interval varying for 2 weeks to 1 year 6 months after initiating therapy and remitted when the previous anticonvulsant drug was discontinued and either substituted with another drug or the patient was left without any treatment. Once the initial antiepileptic drug was discontinued and after a period roughly proportional to the duration of the clinical-EEG complication, the evolution of the patients' seizures was not unusual for this type of epilepsy, with patients eventually becoming free of both seizures and medication and reaching normal school achievement. The clinical complications cannot be attributed solely to the drugs. It must also be related to the underlying substract (i.e., the specific epileptic syndrome involved) that in some patients becomes susceptible to atypical evolution when either product is administered.