Abstracts

Rationale: Anterior temporal lobectomy (ATL) is still a standard surgery in refractory temporal lobe epilepsy (TLE). However, the relationships between the resected area and postsurgical cognitive changes have not sufficiently nor systematically been evaluated. Methods: We investigated 142 patients with TLE (74 left TLE, 68 right TLE), who underwent ATL in University College London. We mapped the resected cavity in the postsurgical MRI, and then spatially normalized it to MNI space. The cavity images and postsurgical changes of verbal and visual learning were non-parametrically analyzed by voxel-based lesion-symptom mapping (VLSM). We also analyzed the associated areas with seizure outcome by the same method. A p-value <0.05 (false discovery rate) was deemed significant. Results: In left TLE, there’s a significant correlation with verbal learning changes mainly in the posterior hippocampus. The posterior fusiform gyrus showed a significant correlation with visual learning changes. Seizure freedom was associated with more anterior part of the hippocampal body in left TLE. In right TLE, there’s no area correlating with verbal learning function. We found a significant correlation with visual learning around the superior temporal gyrus. There’s no significant correlation with seizure outcome in right TLE. Conclusions: In ATL for left TLE, resection of the posterior hippocampus may worsen verbal learning function, and resection of the posterior fusiform gyrus may affect visual learning dysfunction. In right TLE, there’s an associated area in the superior temporal gyrus with visual learning. Our findings add to the growing body of evidence that challenges the material specific model of memory function in TLE patients. Funding: Postdoctoral fellowship from Uehara Memorial Foundation (to DS)