The Role of the Transeptal Window in Endoscopic Endonasal Access to the Contralateral Orbit

Objective  This study aimed to objectively compare maneuverability at the contralateral medial orbit when approached through the traditional endoscopic endonasal approach (EEA) and EEA with transeptal window (TW). Study Design  Anatomic dissections were performed bilaterally on three latex-injected cadaveric heads.  Approaches were performed sequentially; initially, an EEA was fashioned. Binostril access was achieved through a 2-cm posterior septectomy. The second stage pertained to the TW dissection. Area of exposure (AoE), surgical freedom (SF), and angles of attack (AoA) were measured along the contralateral medial orbital wall and compared for each approach. Additionally, the study presents an illustrative case describing the application of the EEA + TW for resection of an intraorbital schwannoma. Results  Compared with EEA, EEA + TW yielded a significantly greater AoE along the contralateral medial orbital wall (39.45 vs. 48.45 cm ² , respectively; p  = 0.002). SF was statistically different between the EEA and EEA + TW (1153.25 vs. 2256.33 cm ² , respectively; p  = 0.002). AoA in the horizontal plane were significantly broader with the EEA + TW (6.36 vs. 4.9 degrees by EEA; p  = 0.015). A 50-year-old male with a right medial extraconal orbital tumor was successfully treated through an EEA using the transeptal corridor to access the medial orbital region. No long-term complications were encountered after 31 months of follow-up. Conclusion  EEA + TW is a minimally invasive technique that maximizes exposure and maneuverability within the medial orbital wall, allowing resection of lesions that extend anteriorly. EEA + TW limits disruption of the nasal septum and overcomes the obstacle that intranasal anatomy represents for instrumentation.