Fully endoscopic supraorbital keyhole approach to the anterior cranial base: A cadaveric study

The supraorbital keyhole approach for anterior cranial base lesions has been increasingly used in clinical practice. Anatomical studies focusing on the endoscopic anatomy via this approach are few, although the microscopic anatomy has been well studied. The aim of this study is to describe the anatomical features and surgical exposure provided by the endoscopic supraorbital keyhole approach using quantitative measurements.

Nine formalin-fixed human cadavers from the inventory of the Anatomy department were used. A total of 18 supraorbital keyhole cranitomies were conducted. The distances between the target anatomical structures and the dura mater at the craniotomy site, and the distances between deep anatomical structures were measured with purpose-designed hooks.

The distance between the dura mater and optic canal was measured as 69.5 ± 6.7 mm (62-83 mm); optic chiasm as 76.2 ± 5.4 mm (67-86 mm); anterior communicating artery as 82.6 ± 6.1 mm (71-93 mm); internal carotid artery (ICA) bifurcation as 74.7 ± 6.0 mm (66-84 mm) and the basilar tip as 94.9 ± 7.0 mm (87-111 mm). The mean diameter of the optic canal was 7.4 ± 1.3 mm (6-11 mm), whereas the mean diameter of diaphragma sellae was measured as 8.4 ± 1.1 mm (7-10 mm).

The results of this study showed that the anterior and medial aspects of the anterior cranial fossa can be visualized properly. Dissection of the ipsilateral arteries of Circle of Willis can be performed easily using an endoscopic supraorbital keyhole approach.