The Ultimate Skull Base Approach Doesn't Involve Cutting Bone: Quantifying the Relative Benefit of Interfascial Temporalis Dissection

Objective: The pterional approach is the most well-known approach in neurosurgery. The approach, and its variations, provide access to the sylvian fissure, as well as numerous deeper structures within the basal cisterns, such as the circle of Willis, the suprasellar region, and the upper reaches of the posterior fossa. To increase the surgical exposure of this approach, numerous adjunctive ostial skull base maneuvers have been proposed, including orbital and/or zygomatic osteotomies, aggressive sphenoidotomy, and anterior clinoidectomy. One of the easiest ways to increase illumination and working angles, however, does not involve bone: the interfascial temporalis muscle dissection. Our study aimed to quantitate this increase in exposure, and compare its relative benefit to more time-consuming and potentially morbid approaches such as the orbitozygomatic osteotomy. Methods: To compare the pterional approach and its extensions, sequential dissections were performed on each of 10 sides of 5 fixed, silicone-injected cadaver heads. On each side, a myocutaneous type dissection (pterional-MC), then an interfascial temporalis dissection (pterional-IF), and finally a frontotemporo-orbitozygomatic (FTOZ) approach were performed. The amount of sphenoid drilling, scalp retraction, and brain retraction were standardized in all specimens. In each category, surgical angles were measured on four deep targets: the tip of the anterior clinoid process, the internal carotid artery terminus, the origin of the posterior communicating artery, and the anterior communicating artery. For each deep target, five surgical angles were measured. Anterior–posterior (AP) angles included a medial, mid, and lateral measurement. Medial–lateral (ML) angles included an anterior and mid measurement. Results: Comparing the interfascial approach to the myocutaneous one, we noted increases in the AP-mid, AP-lateral, and ML-anterior working angles for all deep targets ( p