The extended endoscopic endonasal approach to the clivus and cranio-vertebral junction: anatomical study

Abstract

Lesions located in the retroclival area and at the level of the cranio-vertebral junction are typically approached through a variety of anterior, antero-lateral and postero-lateral skull-based approach, either alone or in combination. The aim of this anatomical study was to demonstrate the possibility of an endoscopic endonasal approach to the clivus and cranio-vertebral junction. Five fresh cadaver heads injected with colored latex were used. A modified endonasal endoscopic approach was made through two nostrils in all cases. Endoscopic dissections were performed using rigid endoscopes, 4 mm in diameter, 18 cm in length, with 0 degrees lenses. Access to the clivus was possible using a lower trajectory when compared to that necessary for the sellar region. The sphenoid sinus is entered, and its inferior wall is completely removed, permitting the union of the sphenoidal and rhinopharyngeal parts of the clivus. The entire clivus can be removed, and the cranio-vertebral junction is opened, removing the anterior arch of atlas and the odontoid process. After the opening of the dura, the anterior surface of the pons and upper spinal cord with corresponding nerves and vasculature are visible. The endoscopic endonasal approach to the clivus and cranio-vertebral junction could be a valid alternative for surgical treatment of anterior lesions of these regions. Adequate endoscopic skill, lab training on cadavers and dedicated tools are required for clinical applications of the approach.