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Objective This prospective study compared pre-surgical language localization with visual naming associated high-γ modulation (HGM) and conventional electrical cortical stimulation (ECS) in children with intracranial electrodes. Methods Drug-resistant epilepsy patients undergoing intracranial monitoring were included if able to name pictures. ECoG signals were recorded during picture naming (overt and covert) and quiet baseline. For each electrode the likelihood of high-γ (70–116 Hz) power modulation during naming task relative to the baseline was estimated. Electrodes with significant HGM were plotted on a 3D cortical surface model. Sensitivity, specificity, and accuracy were calculated compared to clinical ECS. Results Seventeen patients with mean age of 11.3 years (range: 4–19) were included. In patients with left hemisphere electrodes (n=10), HGM during overt naming showed high specificity (0.81, 95% CI 0.78–0.85), and accuracy (0.71, 95% CI 0.66–0.75, p<0.001), but modest sensitivity (0.47) when ECS interference with naming (aphasia or paraphasic errors) and/or oral-motor function was regarded as the gold standard. Similar results were reproduced by comparing covert naming associated HGM with ECS naming sites. With right hemisphere electrodes (n=7), no ECS naming deficits were seen without interference with oral motor function. HGM mapping showed a high specificity (0.81, 95% CI 0.78–0.84), and accuracy (0.76, 95% CI 0.71–0.81, p=0.006), but modest sensitivity (0.44) compared to ECS interference with oral motor function. Naming-associated ECoG HGM was consistently observed over Broca’s area (left posterior inferior frontal gyrus), bilateral oral/facial motor cortex, and sometimes over temporal pole. Significance This study supports the use of ECoG HGM mapping in children where adverse events preclude ECS, or as a screening method to prioritize electrodes for ECS testing.

HGM associated with story listening is a specific determinant of left hemisphere ESM language sites. It can be used for presurgical language mapping in children who cannot cooperate with conventional language tasks requiring active engagement. Incorporation of additional language tasks, if feasible, can further improve the diagnostic accuracy of language localization with HGM.