Abstracts

To evaluate the effects of various types of epilepsy surgery on cognitive functioning as indicated by psychometric intelligence, on a two-year follow-up. Additional aims were to evaluate whether surgery type or lateralization aswell as age, gender, pre-surgical IQ or postsurgical seizure control of the patient have any effect. Between 1991 and 2001 70 operations were performed to the patients aged between 3 and 18 years in the Epilepsy Surgery Program of Helsinki University Central Hospital. 50 of operations were either resections or hemispherotomies. Preoperative neuropsychological testing and a follow-up of two years were available for 20 patients with temporal lobe resections (TLR) and for 6 patients with extratemporal or multilobar resections (EMLR) and for 7 patients with hemispheretomy (HE-T). 18 patients had left sided and 17 patients right sided surgery. The seizure outcome of 27 patients was good (Engel 1-2). WISC-R or WPPSI-R or WAIS-R depending on the age were administered within 6 months before surgery and 6 months and two years after surgery. Verbal IQ(VIQ) varied between 41 and 133 and performance IQ between 41 and 118 before operation. IQ values remained relatively constant during the follow-up and no effect was connected to the type of surgery. All IQ values were significantly lower in the patients with left-sided surgery as well in the patients who underwent HE-T. Preoperative IQs of younger children and also for boys were already lower than those of older children and girls. The same was observed after surgery. Seizure outcome had no effect on postoperative IQ-values either. Altogether 14 patients showed more than 1 SD change of VIQ or PIQ during follow-up; 6 improved and 8 deteriorated. Epilepsy surgery does not affect cognitive functioning of children or adolescents measured by psychometric IQ values. Lower IQ-values pre- and postoperatively were connected to left-sided surgery, male gender and HET as a type of surgery. (Supported by a research grant from the Hospital for Children and Adolescents, Helsinki University Hospital)