Determinants of IQ outcome after focal epilepsy surgery in childhood: A longitudinal case-control neuroimaging study

Modest improvements in IQ in children with epilepsy who underwent epilepsy surgery, a finding which was not seen in children with severe epilepsy who did not undergo surgery. 

According to study results published in Epilepsia the clinical factors associated with IQ increases were lower preoperative IQ and longer follow‐up duration, whereas seizure and antiepileptic medication cessation were not predictive. Among neuroimaging factors, we observed that left anterior temporal resections impacted negatively on verbal reasoning, linked to full‐scale IQ decline. In contrast, gray matter volume change in ipsi‐ and contralesional hemispheres was positively correlated with IQ change. Voxel‐based morphometry identified the gray matter volume change in the contralesional dorsolateral frontal cortex as most strongly associated with IQ improvement

Fifty‐two children (28 boys, 24 girls) were evaluated for epilepsy surgery and reassessed on average 7.7 years later. In the intervening time, 13 were treated pharmacologically and 39 underwent focal surgery (17 temporal, 16 extratemporal, six multilobar; mean age at surgery = 14.0 years). Pre‐ and postsurgical assessments included IQ tests and T1‐weighted brain images. Predictors of IQ change were investigated, including voxel‐based analyses of resection location, and gray and white matter volume change.

The study shows that a variety of factors are likely to contribute to patterns of postsurgical change in IQ. Neuroimaging results indicate that left anterior temporal resections constrain development of verbal cognition, whereas simultaneously cortical growth after surgical treatment can support improvements in IQ.