Endoscopic Endonasal Approach to the Orbit: A Cadaveric Study and Case Series Emphasizing the Benefits of Ipsilateral Mononostril Technique

Abstract Background Lesions located in the orbit are challenging to manage due to the enclosed space they occupy and their close proximity to critical anatomical structures. The challenge has been to develop a surgical approach that achieves the goal of obtaining complete tumor removal while preserving functional anatomy. Our aim is to understand the surgical anatomy of the orbital apex and inferomedial orbital structures via the ipsilateral endoscopic endonasal approach (EEA) and its feasibility in clinical practice. Methods Five fresh human head specimens were prepared for dissection. Anatomic dissections were performed by using rigid endoscopes, attached to a high-definition camera and a digital recording system. To achieve a meticulous understanding of the anatomy, an EEA to the sellar region was performed by involving a wide bilateral sphenoidotomy, posterior and anterior ethmoidectomy and orbital dissection in a stepwise manner. A retrospective evaluation was carried out with patients who underwent surgery through the ipsilateral mononostril EEA between August 2018 and August 2022. Results The results of endoscopic endonasal cadaveric dissections showed that the medial, inferomedial, and apex portions of the orbit can be accessed through the ipsilateral EEA. Eighteen patients who underwent EEA surgery for various pathologies, 72% of the lesions were intraconal. The patients were between the ages of 17 and 54 (mean 34,1 ± 8,6). The left orbit was affected more commonly (11 left, 7 right) and the most common pathology was intraorbital cavernous hemangioma (13). The average postoperative follow up duration was 22.2 months (range 6 months – 50 months). Conclusion Our study highlights the potential benefits of using a purely ipsilateral mononostril EEA for orbital surgery, particularly for accessing medial and inferomedial orbital lesions, and utilizing the knowledge gained from cadaveric dissection experience. This technique has the potential to reduce morbidity and improve outcomes, especially when used in conjunction with careful patient selection, preoperative planning, and advanced endoscopic skills. Given the limited literature on the subject, we believe that our study, which presents a large case series of orbital pathology operated with the ipsilateral mononostril EEA method, will provide valuable contributions to the literature and guide surgeons considering this approach.