Stereo-electroencephalography (SEEG) : The New Frontier in Localization of Epileptic Foci

Abstract

  An intracranial electroencephalography study is used as a complement to non-invasive studies to delineate the epileptogenic zone and map the functional zone in relation to the epileptogenic zone. Stereoelectroencephalography (SEEG) is a method used to study intracranial electroencephalography. It is superior to subdural electrodes, especially in cases of difficult-to-localize epilepsy, which are increasingly considered for surgery. It was approved for insurance reimbursement in Japan in 2020 and is being increasingly utilized. The success of an SEEG study relies heavily on the working hypothesis constructed prior to implantation, based on seizure semiology, and the findings of non-invasive studies. Comparisons with subdural electrode studies, which have been the mainstream in Japan, are featured to facilitate the understanding of some aspects of SEEG. This article covers the indications, hypothesis constructions, interpretations of the recordings, technical considerations including surgical techniques, and surgical outcomes, with the aim of providing an introductory guide to SEEG.