Endoscopic Contra-Lateral Transmaxillary Approach to the Orbital Roof

Background: The contra-lateral transmaxillary (CTM) approach to the skull base utilizes the maxillary sinus as a corridor for access contra-lateral skull base regions. Recently, use of the CTM approach in conjunction with a traditional endoscopic endonasal approach (EEA) has shown feasibility in expanding access to the petrous apex and petroclival region, allowing for a more favorable angle of attack without extensive manipulation of the ICA. We performed a proof-of-concept study in order to assess the feasibility of using the CTM approach to gain access to the orbital roof and apex. Methods: Anatomical dissection was performed in 2 cadaver heads. A Caldwell-Luc approach, ipsilateral medial maxillectomy and superior septectomy were performed. Instruments were inserted through the maxillary sinus to reach the contra-lateral orbit. A 30 degree endoscope with 4mm diameter and 175 mm length was inserted through the nostrils to allow visualization of the orbit. Results: The CTM approach provided a favorable angle of instrumentation, enabling complete resection of the orbital roof. This approach also facilitated direct access to the anterior clinoid and orbital apex. By further widening the anterior extent of the medial maxillectomy, exposure could be extended to the posterior table of the frontal sinus. Endoscopic visualization through the Caldwell-Luc corridor provided a unique, panoramic view of the orbit and skull base, an anatomical perspective rarely achievable in live surgery and typically only appreciated in sagittally split cadaveric dissections. However, this expanded exposure came at the cost of increased morbidity relative to standard endonasal techniques, requiring both a Caldwell-Luc incision and a superior septectomy. Conclusion: An endoscopic CTM approach to the skull base offers an attractive alternative to transcranial approaches, affording expansive access to the anterior cranial base as well as orbital apex and roof in this proof-of-concept study. We plan to undertake further study with cadaveric studies on 5 cadavers to assess this novel approach and compare access to described transorbital approaches. Fig. 1 Resection of the lateral portion of the orbital roof (instrument through nasal cavity) Fig. 2 Resection of the lateral part of the orbital roof (instrument through transmaxillary incision) Fig. 3 View of posterior table of frontal sinus after anterior extension of the medial maxillectomy (sagittal view) Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany