Technical Aspects of SEEG and Its Interpretation in the Delineation of the Epileptogenic Zone PDF

S pecial T opic doi: 10.2176/nmc.st.2020-0176 Neurol Med Chir (Tokyo) 60, 565–580, 2020 Online November 6, 2020 Technical Aspects of SEEG and Its Interpretation i...

S pecial T opic doi: 10.2176/nmc.st.2020-0176 Neurol Med Chir (Tokyo) 60, 565–580, 2020 Online November 6, 2020 Technical Aspects of SEEG and Its Interpretation in the Delineation of the Epileptogenic Zone Hui Ming KHOO,1 Jeffery A. HALL,2 Francois DUBEAU,2 Naoki TANI,1 Satoru OSHINO,1 Yuya FUJITA,1 Jean GOTMAN,2 and Haruhiko KISHIMA1 1 Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan 2 Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada Abstract Stereo-electroencephalography (SEEG) has gained global popularity in recent years. In Japan, a country in which invasive studies using subdural electrodes (SDEs) have been the mainstream, SEEG has been approved for insurance coverage in 2020 and is expected to gain in popularity. Some concepts supporting SEEG methodology are fundamentally different from that of SDE stud- ies. Clinicians interested in utilizing SEEG in their practice should be aware of those aspects in which they differ. Success in utilizing the SEEG methodology relies heavily on the construction of an a priori hypothesis regarding the putative seizure onset zone (SOZ) and propagation. This article covers the technical and theoretical aspects of SEEG, including the surgical techniques and precautions, hypothesis construction, and the interpretation of the recording, all with the aim of providing an introductory guide to SEEG. Keywords: SEEG, epilepsy, epileptogenic zone, electrical stimulation, radiofrequency thermocoagulation Introduction delimiting the EZ and defining the eloquent areas in relation to the EZ and (2) radiofrequency thermo- Stereo-electroencephalography (SEEG) is a method- coagulation (RF-TC) to treat a deep-seated EZ (or ology to confirm or refute the hypothesis generated epileptogenic lesion) or EZ in the proximity to the to delineate the epileptogenic zone (EZ) from the eloquent cortex,2) and to complement SEEG findings sum of non-invasive preoperative work-up in patients in delineating the EZ (details to be discussed later). with pharmaco-resistant focal epilepsy. The term SEEG was first performed around 60 years ago in “SEEG” does not refer to the surgical technique of France, at the Sainte-Anne Hospital, by Jean Talairach inserting intracerebral electrodes per se. Neither is and Jean Bancaud3) and has since been used in depth electrode study a synonym because SEEG is France, Italy, and Canada.4–6) SEEG was adopted in not a method to record only from the depths, although the United States around 2013, following the increase it possesses a strength in recording from deep struc- in surgeries of extratemporal and non-lesional tures compared to other invasive studies. Indeed, epilepsies in major centers and the overall poor SEEG is a methodology that allows three-dimensional success rates for localization and surgery based on recording of activity anywhere in the brain, and is other intracranial approaches including subdural utilized to delineate not only the EZ1) but also the electrode (SDE) exploration.7,8) Its quick gain of epileptic network that contributes to the clinical popularity in a number of North American centers manifestations of a seizure. Moreover, SEEG electrodes over a few years has contributed to the mounting can be used for (1) cortical electrical stimulation in recent evidence suggesting that SEEG is safer than SDE study. In contrast to the reported complication rates of SDE (5%–17%),9–13) a meta-analysis on 4000 Received May 29, 2020; Accepted September 1, 2020 patients has shown that the rate is much lower Copyright© 2020 by The Japan Neurosurgical Society This (