2025 Proffered Presentations
S308: ENDOSCOPIC ENDONASAL APPROACH TO THE INFEROLATERAL ORBITAL QUADRANT: AN ANATOMICAL CADAVERIC STUDY
Alejandra Rodas, MD; Leonardo Tariciotti, MD; Youssef M Zohdy, MD; Roberto M Soriano, MD; Emily Barrow, MD; Gustavo Pradilla, MD; John M DelGaudio, MD; Emory University
Introduction: Intraorbital tumor resection was formerly performed solely through craniofacial approaches. However, these can require extensive soft tissue dissection and bone work. An improved armamentarium and experience with endoscopic sinonasal approaches have paved the way for successful surgical excision of intraconal orbital lesions through the endonasal route. During preoperative evaluation, important consideration must be given to the volume and location of the orbital lesion. To date, the endonasal corridor is advised for lesions that occupy the inferomedial aspect of the orbit, establishing the optic nerve axis as the lateral limit for resection feasibility. In cases with lateral tumoral extension combined approaches are favored. Nonetheless, additional anatomical studies are required to identify the most lateral plane that is accessible through endoscopic endonasal surgery.
Method: Anatomical dissections were performed bilaterally on four latex-injected human cadaveric specimens. Through an endoscopic endonasal approach, an ipsilateral maxillary antrostomy and complete ethmoidectomy was performed. A medial orbitotomy was then fashioned resecting the lamina papyracea and the inferomedial aspect of the orbital floor, establishing the infraorbital nerve as the lateral limit for dissection. Once the periorbita was carefully incised, the inferior rectus muscle was mobilized medially, exposing the inferolateral quadrant. Using imaging-based navigation, maneuverability was assessed based on objective measurements. The most superolateral point that could be reached through the endonasal corridor was assessed in relation to the optic nerve.
Results: Following dissection and removal of the extraconal fat, the inferior rectus muscle was carefully retracted medially and superiorly, exposing the inferolateral intraconal quadrant. The oculomotor branch for the inferior rectus muscle was identified in all the specimens. Significant maneuverability was attained at the inferolateral quadrant, and the most superolateral point reached through this corridor stood lateral to the optic nerve in all the specimens within a mean distance of 1.45 cm (0.37 cm). The vertical angle of attack for this specific point was superior to the horizontal angle of attack.
Conclusion: Resection of laterally based intraconal orbital lesions is feasible through the ipsilateral endoscopic endonasal corridor. Enhanced maneuverability can be attained by working both medial and lateral to the inferior rectus muscle. The most superolateral point reachable through the endonasal route stood lateral to the optic nerve in all the dissections performed for this study. Angled instruments and scopes are of benefit and facilitate maneuverability of structures deviating from the midline. Partial resection of the lamina papyracea and medial aspect of the orbital floor do not prompt reconstruction.