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Purpose: To characterize the spatial and temporal course of ictal high‐frequency oscillations (HFOs) recorded by subdural EEG in children with intractable neocortical epilepsy.

Methods: We retrospectively studied nine children (four girls, five boys; 4–17 yr) who presented with intractable extrahippocampal localization‐related epilepsy and who underwent extraoperative video subdural EEG (1000 Hz sampling rate) and cortical resection. We performed multiple band frequency analysis (MBFA) to evaluate the frequency, time course, and distribution of ictal HFOs. We compared ictal HFO changes before and after clinical onset and postsurgical seizure outcomes.

Results: Seventy‐eight of 79 seizures showed HFOs. We observed wide‐band HFOs (∼250Hz, ∼120 electrodes) in six patients either with partial seizures alone (three patients) or with epileptic spasms (three patients). Three patients with partial seizures …