2026 Poster Presentations
P348: ENDOSCOPIC HIPPOCAMPECTOMY VIA TRANS-ORBITAL AND MIDDLE TEMPORAL GYRUS CORRIDORS: ANATOMY, TECHNIQUES, OUTCOMES, AND SURGICAL CONSIDERATIONS
Hyun Keun Ji, MD1; Min Ho Lee, MD, PhD1; Kyoung Su Sung, MD, PhD2; Hyuk Jin Oh, MD, PhD3; Tae-Kyu Lee1; 1Uijeongbu St. Mary's Hospital, The Catholic University of Korea; 2Dong-A university hospital; 3Soonchunhyang Univ. Cheonan hospital
Objective: Mesial temporal lobe epilepsy is the most common form of focal epilepsy and is often refractory to medical treatment. Although hippocampectomy has demonstrated excellent seizure outcomes, traditional open approaches carry risks of visual, cognitive, and cortical complications. Recent advances in endoscopy have enabled less invasive trans-orbital and trans–middle temporal gyrus routes to the hippocampus. This review compares these two endoscopic approaches in terms of anatomical feasibility, clinical outcomes, and surgical risks.
Methods: An AI-assisted systematic search of PubMed, Embase, and Scopus was conducted up to May 2025. Studies were included if they described purely endoscopic or endoscope-assisted hippocampectomy via the trans-orbital or trans–middle temporal gyrus approach, and provided extractable anatomical or clinical data. Cadaveric feasibility studies and clinical series were analyzed for seizure outcomes, visual field changes, and complications. Diffusion-tensor imaging–based tractography was additionally performed to illustrate surgical trajectories relative to Meyer’s loop.
Results: Seven studies met the inclusion criteria, comprising three cadaveric and four clinical investigations with a total of 14 patients (13 trans-orbital/anterior, 1 trans–middle temporal gyrus/lateral). Both approaches allowed consistent exposure of the hippocampus and amygdala. All reported patients achieved seizure freedom during follow-up. No visual field defects or permanent morbidity were documented. Cadaveric studies demonstrated up to 97% hippocampal exposure through the trans-orbital route, while the trans–middle temporal gyrus approach provided shorter and more direct access at the expense of cortical transgression.
Conclusion: Endoscopic trans-orbital and trans–middle temporal gyrus approaches appear to be safe and feasible minimally invasive alternatives to traditional hippocampectomy. The trans-orbital route minimizes cortical disruption but carries orbital risks, whereas the trans–middle temporal gyrus route offers wider access but greater potential for neocortical and visual pathway injury. Larger prospective studies with standardized outcome measures are needed to define comparative efficacy, patient selection, and long-term results.