Endoscopic Transnasal Approach

Abstract

Craniovertebral junction (CVJ) is a complex joint defined by the outer aspect of the foramen magnum, i.e., the occipital condyles and the first two cervical segments, namely the atlas and the axis. It covers and protects the caudal brainstem and rostral spinal cord. CVJ is the most mobile region of the cervical spine, as it permits complex movements providing stability without compromising the traversing neurovascular elements.

Historically, different routes such as anterior, lateral, and posterior approaches were described to access the CVJ and eventually manage diseases involving this area. Anterior approaches include transoral, transoral-transmaxillary, transoral-translabiomandibular, and transfacial routes; lateral access is obtained through the retrosigmoid and the presigmoid/transpetrosal approaches, which may be eventually enlarged with a petrosectomy resulting in an extended transpetrosal approach; finally, posterolateral routes such as suboccipital and the far-lateral approaches should be taken into account. Albeit these routes represent extensive skull base approaches, they provide a thorough kaleidoscope of strategies of accessing the CVJ, especially backing upon the possibility of combining them. In more recent times, the increasing use of the endoscope in transsphenoidal surgery has allowed the endonasal route to be considered for the management of different lesions at the skull base. Indeed, the wider and panoramic view offered by the endoscope along with the refinement of surgical techniques and instrumentations has expanded its applicability to lesions of the CVJ. We herein present the surgical nuances and the related anatomy of the different approaches and of the endoscopic endonasal technique to access the CVJ and manage lesions of this area, aiming to highlight the feasibility and indications of this route and evaluate advantages and limitations, also in regard to the relevant anatomy.