2026 Poster Presentations
P332: CLINICAL INSIGHTS FROM SEEG-GUIDED RESECTIONS FOR TEMPORAL LOBE EPILEPSY: A CASE SERIES
Melissa Owusu-Ansah1; Aditya Katewa1; Landon Power1; Nikita Das1; Efstathios Kondylis, MD2; Juan Bulacio, MD2; Demitre Serletis, MD2; William Bingaman, MD2; 1Case Western Reserve University School of Medicine; 2Cleveland Clinic
Introduction: Temporal lobe epilepsy (TLE) is the most common focal epilepsy, accounting for nearly 60% of cases, with peak incidence in early adulthood. Despite advances in antiseizure medications, 30–50% of patients remain drug-resistant and may benefit from surgical intervention. For screened patients, surgical options including anteromesial temporal lobectomy, selective amygdalohippocampectomy, and stereotactic laser ablation have demonstrated reasonably high rates of seizure freedom. In nearly one-third of refractory cases, invasive monitoring by stereoelectroencephalography (SEEG) is necessary to localize the epileptogenic zone (EZ), particularly in patients with non-lesional imaging, discordant non-invasive studies, or multifocal seizure activity. In this context, there is limited literature on how SEEG findings may be used to tailor the resective surgical strategy in TLE.
Methods: We conducted a single-center, retrospective case series review of patients undergoing surgical intervention for refractory TLE from 2022 to 2023. Inclusion criteria were temporal lobe resection following SEEG evaluation, availability of a six-month post-op MRI, and at least one-year of clinical follow-up. Patients with prior temporal lobe resection, no surgical intervention, or incomplete imaging/follow-up were excluded. Data collected included demographics, seizure history and semiology, preoperative workup (EEG, MRI, fMRI, PET/SPECT/MEG, neuropsychological testing), SEEG implantation details, operative findings, pathology, and postoperative outcomes. Surgical outcomes were assessed using Engel classification at one year post-operatively.
Results: Twenty-eight patients met inclusion criteria. The median age at surgery was 33 years (IQR 24–42), with a median epilepsy duration of 5 years (IQR 4–18). SEEG was most often indicated for non-lesional MRI (86%) or poorly localized seizure onset (39%)(Figure 1). Implantation involved a median of 19 electrodes (IQR 17–21), of which a median of 5 SEEG contacts (IQR 4–7) were ultimately resected. Seizure onset zone localization was successful in 26 patients (93%). Pathology most frequently demonstrated gliosis (n=18) and focal cortical dysplasia (n=16)(Figure 2). Complications included radiographic subarachnoid hemorrhage in 9 patients (32%) without clinical sequelae, and one clinically significant hemorrhage (3.6%). Resection types included standard anteromesial temporal lobectomy, temporopolar resections with or without mesial structures, and more tailored sub-lobar resections confined to specific gyri or sulcal banks (Figure 3). The majority of resections involved temporal pole, superior temporal gyrus, and mesial temporal structures (electrodes A, B, E, I, T), while other electrode sites (D, G, J, O, Q, V, W, X, Z) were rarely resected(Figure 4). This distribution suggests that SEEG not only identifies seizure onset zones but also spares unnecessary regions, thereby tailoring resections to the epileptogenic network.
Conclusions: In patients with refractory temporal lobe epilepsy, SEEG-guided resections achieved favorable seizure outcomes while typically involving resection of fewer electrode-monitored regions than implanted. SEEG may refine surgical targeting and limit the extent of tissue removal. Ongoing work will include volumetric comparisons of pre- and postoperative MRI to validate this trend and further guide electrode selection strategies.