Neuronavigation-guided Frameless Stereoelectroencephalography (SEEG)

Stereoelectroencephalography (SEEG) is an invasive surgical procedure used to identify epileptogenic zones. The combination of both subdural grids and depth electrodes (DEs) is currently used for invasive intracranial monitoring in many epilepsy centers. To perform DE implantation, some centers use frame-based stereotactic techniques and others use stereotactic robotic techniques. However, not all epilepsy centers have access to these tools. We hypothesized that DE implantation using a neuronavigation system can be utilized for subsequent epilepsy surgery. Between April 2016 and April 2017, we performed invasive monitoring for 26 patients. Among these, 17 patients (8 females, 9 males; mean age, 21.2 years; range, 3-51 years) underwent DE implantation. We divided patients into three groups: Group 1 (7 patients), a free-hand implantation group; Group 2 (7 patients), a frameless stereotactic implantation group; and Group 3 (3 patients), a computed tomography (CT)-guided auto image registration system with the stereotactic implantation group. Group 3 showed the closest distance from planned target to DE tip, followed by Group 2. Fourteen of the 17 patients underwent subsequent epilepsy surgery referring to the results of DE studies. DE placement using a neuronavigation system without stereotactic robotic equipment or frame-based stereotactic techniques can be utilized for subsequent epilepsy surgery.