The role of magnetoencephalography in the presurgical evaluation of patients with MRI-negative operculo-insular epilepsy.

•MEGSSs were shown in the operculo-insular region in 11/13 patients with negative MRI.•MEG findings changed the plan of intracranial electrode implantation in 5 patients.•Intracranial recording showed frequent spikes in the region where MEGSSs concentrate.•Removing the cortex with frequent spikes and with MEGSSs resulted in good outcome.•MEG played an additional role in localising MRI-negative operculo-insular epilepsy.