Transition from Subdural Electrocorticography to Stereo-electroencephalography in Presurgical Evaluation of Epilepsy: Single-institutional Experience

Stereo-electroencephalography has recently gained attention as a less invasive and effective technique for presurgical evaluation in patients with drug-resistant epilepsy. Several studies have reported favorable outcomes when compared to conventional subdural electrode implantation. This study aimed to compare the target regions, complications, additional surgeries, and surgical outcomes between stereo-electroencephalography and subdural electrode implantation. A retrospective review was conducted on 83 consecutive patients who underwent intracranial electrode implantation between 2018 and 2024. Clinical variables were compared between the subdural electrode implantation (n = 41) and stereo-electroencephalography (n = 42) groups. In the stereo-electroencephalography group, 28 cases (66.7%) were implanted in the insular gyrus as the deep area, which was significantly different from the subdural electrode implantation group (8 cases, 19.5%). Resective surgery was performed in 39 subdural electrode implantation cases. In the stereo-electroencephalography group, 20 patients underwent resection, 14 received thermocoagulation, 5 were scheduled for surgery, and 3 were not eligible for surgery because the epileptogenic zone could not be identified. Intracranial hemorrhage occurred in 3 cases in each group. Two subdural electrode implantation cases were symptomatic and required reoperation, whereas all stereo-electroencephalography-related hemorrhages were asymptomatic. One year after surgery, seizure freedom was achieved in 57.9% (22 of 38 cases) of subdural electrode implantation and 64.0% (16 of 22 cases) of stereo-electroencephalography patients (p = 0.606). Seizure outcomes and complication rates were similar between stereo-electroencephalography and subdural electrode implantation, with fewer serious complications in the stereo-electroencephalography group. Stereo-electroencephalography was more frequently used in cases involving deep lesions or prior subdural implantation, highlighting its utility in technically challenging cases.