Surgical versus medical treatment for severe epilepsy: consequences for intellectual functioning in children and adults. A follow-up study.

We compared the effects of medical and combined surgical and medical treatment of refractory epilepsy on intellectual functioning in a group of children (n=13) and a group of adults (n=15). The patients were tested with the age-appropriate versions of Wechsler's intelligence scales twice prior to and once after epilepsy surgery. There were no significant differences between the groups in preoperative epilepsy-related variables, including age at onset. The IQ scores were submitted to two-way analyses of variance (ANOVA). We also evaluated individual changes in IQ scores. Adult patients maintained stable levels of performance after drug treatment as well as following surgery, while children declined in Full Scale IQ after both kinds of treatment. Children also declined in Performance IQ, but not in Verbal IQ after drug treatment, and in Verbal IQ, but not in Performance IQ after surgery. Three of six children who underwent a significant decline in Full Scale IQ before surgery did not show any further decline postoperatively. We have proposed a developmental model to account for the different findings in children and adults, and conclude tentatively that refractory, long-standing epilepsy may interfere with intellectual development both during drug treatment and following combined surgical and medical treatment in children, while the impact of long-standing refractory epilepsy of similar severity as in children is not strong enough to reduce intellectual performance in adults, irrespective of treatment modality.