Endoscopic Endonasal Approach to Occipital Condyle: Key to "Far-Medial Approach" - A Cadaveric Study

We present a descriptive anatomical study for the endoscopic endonasal approach to occipital condyle.

To describe the anatomy of various structures encountered during the expanded endoscopic endonasal approach to the occipital condyles and to elaborate on the technical steps for exposure while preventing injury to vital neurovascular structures on the way.

A total of 20 sides in ten human cadavers were evaluated for the research after obtaining informed consent. Cadavers were placed in a deep freezer at -20 degree Celsius before thawing 24 hours prior to the dissection. A standard 0-degree endoscope was used to aid in stepwise dissection to the occipital condyle. Anatomically significant photos and videos were recorded, and appropriate anatomical measurements were taken.

The mean distance from the tip of the nose to the anterior border of the occipital (ToN-aOC) was 10.8 cm, whereas the mean distance between tip of the nose and the anterior border of the hypoglossal canal (ToN-aHG) was 11.4 cm. The average intercondylar distance (aOC-aOC) and interhypoglossal canal distances (aHG-aHG) were 1.3 cm and 3.1 cm, respectively.

This study serves as a stepwise guide for endoscopic endonasal approach to the occipital condyle. This approach warrants the innovation of new longer instruments in comparison to the transsphenoidal approach (15-17 cm vs 12-15 cm). Drilling of the anterior part of the occipital condyle, up to the hypoglossal canal, increases the surgical corridor in the lower lateral clivus.