Abstracts

Rationale: Epilepsy surgery is often considered earlier for younger children, due to evidence suggesting the young brain is more resilient. Our center s recent findings have shown that the post-surgical cognitive outcome is significantly more dependent on duration of epilepsy than age at the time of surgery. The current study extends these findings, with post-hoc analyses of potential contributing surgical variables, including side of surgery, location of resection, presence or absence of a lesion, and Engel Class outcome. Methods: Data from neuropsychological evaluations of 30 children who underwent epilepsy surgery between 2005 and 2012 were analyzed via chart review. Mean age at surgery was 11 years (SD=4). Mean age at seizure onset was 5 years (SD=4). Mean epilepsy duration was 6 years (SD=4). 12 patients (40%) had surgery in the left hemisphere; 6 patients (20%) had surgery in a hemisphere that was classified as language dominant per MSI. 18 temporal lobe resections; 5 extratemporal resections; 7 multilobar resections. Engel Class outcomes: Class I=23, Class II=3, Class III=3, Class IV=1. Mean pre-surgical FSIQ was 85 (SD=16); mean post-surgical FSIQ was 83 (SD=18).Results: Post-surgical FSIQ was significantly correlated with epilepsy duration (r=-0.54, p<0.01) but not with age at time of surgery. Mean FSIQ for patients with epilepsy duration < 5 years (n=15) was 97 (SD=7); mean FSIQ for patients with epilepsy duration > 5 years (n=15) was 72 (SD=17). In post-hoc analyses, the association between epilepsy duration and FSIQ was not otherwise accounted for by any of the following variables: age of seizure onset, side of surgery, surgery in the language-dominant hemisphere, type of resection, Engel Class outcome, number of AEDs after surgery, or time between surgery and testing. Of note, post-surgical FSIQ was significantly associated with number of AEDs tried prior to surgery (r=-0.55, p<0.01) potentially reflecting complicated epilepsy course or chronic effects of more medications on cognition.Conclusions: In our sample, cognitive outcome after epilepsy surgery was associated with duration of epilepsy but not with age at time of surgery, to the exclusion of several potential covariates. These findings advocate for a reconceptualization of risk factors associated with post surgical cognitive decline, namely giving more weight to duration of epilepsy. Data from this study support moving more quickly toward surgery for children of any age, as longer duration of epilepsy is a more robust predictor of cognitive outcome than most other pre-surgical considerations. Additionally, the association between number of AEDs tried prior to surgery, and post-surgical FSIQ suggests that surgical intervention earlier in the course of epilepsy treatment may mitigate these effects and improve long-term cognitive prognosis. Children of all ages, with intractable focal epilepsy, should be considered for surgical intervention as soon as possible.