High-gamma modulation language mapping and cognitive outcomes after epilepsy surgery

Objective: We evaluated changes in cognitive domains after neurosurgical lesioning of cortical sites with significant high-gamma power modulations (HGM) during a visual naming task, although these sites were found language-negative on standard-of-care electrical stimulation mapping (ESM). Methods: In drug-resistant epilepsy patients who underwent resection/ablation after stereo-electroencephalography (SEEG), we computed reliable change indices (RCIs) from a battery of presurgical and 1-year postsurgical neuropsychological assessments. We modeled RCIs as a function of lesioning even one HGM language site, number of HGM language sites lesioned, and the magnitude of naming-related HGM. The analyses were adjusted for 1-year seizure freedom, operated hemispheres, and the volumes of surgical lesions. Results: In 37 patients with 4455 SEEG electrode contacts (1839 and 2616 contacts in right and left hemispheres, respectively), no ESM language sites were lesioned. Patients with lesioning of even one HGM language site showed significantly lower RCIs for Peabody Picture Vocabulary Test (PPVT), working memory, and verbal learning immediate (VLI) scores. RCI declines with higher number of HGM language sites lesioned were seen in PPVT (slope [β] = -.10), working memory (β = -.10), VLI (β = -.14), and letter-word identification (LWI; β = -.14). No neuropsychological domains improved after lesioning of HGM language sites. Significant effects of the HGM magnitude at lesioned sites were seen