Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Clivectomy, Odontoidectomy, and Far Medial Approach

Introduction: The surgical treatment of lesions in and around the clivus is challenging given the deep location and presence of numerous neurovascular structures. To reach this region, endoscopic endonasal approaches (EEAs) and their extensions (far-medial approach and odontoidectomy) have gained popularity as they provide direct access, excellent illumination, and magnification, and provide a trajectory ventral to the cranial nerves of the cerebellopontine angle. Although several cadaveric studies have further refined this relatively new technique, most offer a general anatomical overview of the approach, without providing a step-by-step description that can be adapted to all levels of training. The main goal of this study is to develop a practical educational resource to learn the steps of the transclival EEAs and their extensions for trainees.