Anatomic Basis of Endoscopic Skull Base Surgery and Clinical Implications in 277 Approaches: Part 1 Sella and Cavernous Sinus

The aim of this study was to review the surgical neuroanatomy of the skull base as viewed through an endoscopic transnasal route with image guidance so that endoscopic transnasal approaches to the skull base could be better understood. We also aim to present our clinical experience on skull base endoscopy at Istanbul University over 4 years.

An endoscopic transnasal approach to the sella, superior orbital fissure (SOF), and cavernous sinus (CS) was performed in 10 cadavers at the University of Florida, Department of Neurosurgery. The approaches included a wide sphenoidotomy to reach sella and extended modifications to reach SOF and CS. A Stryker Image Guidance System was used in five cadaveric heads in order to expose the anatomical structures along the surgical path, the trajectory, and the limitations of each approach, which simulated actual surgical procedures in a stepwise manner. In addition, 277 endoscopic skull base approaches were performed by the neurosurgical team between September 2007 and December 2012 at Istanbul University.

The endoscopic transnasal transsphenoidal approach exposed the sella and the structures within the sphenoidal sinus in all cases of cadaveric dissections. Of 277 endoscopic skull base approaches performed in our department, 212 (77 %) were for pituitary adenomas. We used extended modifications of the endoscopic transsellar approach to attack the SOF and/or CS in pituitary adenomas. Detailed knowledge of endoscopic surgical anatomy of the skull base is a prerequisite for safe and effective management of lesions within the sellar, suprasellar, and parasellar areas.