Abstracts

Rationale: Children with medically-intractable epilepsy often benefit from resective surgery, but such procedures may carry a risk for cognitive decline due to disruption of eloquent cortex. Published studies have indicated that children with temporal lobe epilepsy do not exhibit significant changes in intellectual function after resective surgery, but less known about cognitive outcomes associated with resective surgery related to extra-temporal or multi-lobar resection. Methods: This cohort included 26 children with medically-intractable epilepsy who had subdural grid-based surgery. Twelve patients had frontal lobe resection, 4 patients had temporal lobe resection, 3 patients had parietal lobe resection, and 7 patients had multi-lobar resection. We investigated pre- and post-surgical intellectual functioning. Various clinical factors were examined including age of onset, age at surgery, side of surgery, and post-operative seizure status (Engel classification). Results: Baseline, or pre-surgical, intellectual status fell within the low average range for the frontal group (FSIQ = 83), borderline deficient range for the temporal lobe group (FSIQ = 75), mildly deficient range for the parietal lobe group (FSIQ = 68), and mildly deficient range for the multi-lobar group (FSIQ = 65). Changes in intelligence test scores pre- to post-operatively were analyzed with a series of dependent t-tests involving the following domains: overall intellectual functioning (FSIQ), verbal intellectual functioning (VIQ), non-verbal intellectual functioning (NVIQ), working memory (WM), and processing speed (PS). A significant decline was noted in WM (t = 2.26, p = .034) in the mixed clinical sample. Although substantial variability was noted, no other pre- to post-operative change in intellectual functioning reached a statistical level of significance. Side of surgery or age of onset were not associated with outcome on intelligence test measures. A separate analysis was completed for the children who had frontal lobe resection. No significant changes were detected although the WM test scores revealed a trend in the negative direction. Reliable Change Index scores were calculated to assess the frequency of individual changes after surgery. Of the 4 patients who exhibited a statistically-significant decline in overall IQ, 3 were classified as having persistent seizures (Engle III classification). Conclusions: These findings suggest that pediatric patients with medically-intractable epilepsy, as a group do not experience a decline in overall intellectual functioning after resective surgery; however, working memory was found to decline significantly in the overall cohort indicating a significant risk for some patients who may have problems with the mental manipulation of information after resective surgery for epilepsy.