Development of intelligence 4 to 11 years after paediatric epilepsy surgery

Objective. Little is known about the long-term intellectual outcomes following paediatric epilepsy surgery. Change is not likely within the first 2 years following surgery, and the few studies of longer term outcomes have yielded inconsistent results. This study addressed this issue by examining a large group of surgical and non-surgical patients at baseline and after 4-11 years. Methods. Participants were 97 patients (mean age 20.08 [SD: 4.44] years) with childhood-onset intractable epilepsy; 61 had undergone resective epilepsy surgery. Participants underwent neuropsychological testing with the age-appropriate Wechsler Intelligence Scale, generating Full Scale, Performance and Verbal IQs, and Working Memory and Processing Speed indices. Results. In total 54% of the surgical and 39% of the non-surgical patients were seizure free in the preceding 12 months (p >.05); however, surgical patients did achieve seizure freedom sooner and used fewer medications at follow-up. Surgical status was not associated with any cognitive domain. However, with the exception of processing speed, significant seizure status 9 time interaction effects were evident and seizure-free patients had higher scores at follow-up. Regression analyses additionally showed that low pre-operative scores were predictive of improvement overtime, whereas high preoperative scores were predictive of high scores at follow-up. Interpretation. The results show similar intellectual outcomes for surgical and nonsurgical paediatric patients. Four to 11 years after paediatric epilepsy surgery, seizure freedom, whether attained through epilepsy surgery or other means, was found to be associated with intellectual improvements. Seizure status and baseline scores were the most consistent predictors.