Quantitative study of the opticocarotid and carotid-oculomotor windows for the interpeduncular fossa, before and after internal carotid artery mobilization and posterior communicating division.

Abstract

The management of basilar apex (BX) aneurysms remains problematic. We quantified the surgical exposure of the BX through the opticocarotid window (OCW) and the carotid-oculomotor window (COW), before and after mobilization of the internal carotid artery and division of the posterior communicating artery (PCoA). Eleven silicone-injected cadaveric heads were dissected bilaterally. The surgical dissection was divided into 4 major steps: (1) supraorbital modified orbitozygomatic craniotomy, (2) mobilization of the internal carotid artery after drilling out the anterior clinoid process intradurally and cutting the distal dural ring, (3) drilling out the posterior clinoid process and dorsum sellae, and (4) dividing the PCoA from the posterior third portion of the vessel. A frameless navigation system was used to quantify the surgical exposure area of the BX through the OCW and COW. The total surgical area increased significantly from steps 1 to 4 (P < .001) in both OCW and COW groups. Overall, there was a larger total surgical area obtained in the COW compared with the OCW (P = .010). ICA mobilization increased the surgical area for temporary (P < .001) and permanent (P < .003) clip application in both windows. The division of PCoA significantly increased the overall surgical area for permanent clip application (P < .003). Compared with the OCW, the COW had a significantly increased change in the area for permanent clip application in the low-lying group (P = .03). When approaching the BX via the pterion route, the appropriate surgical step and window should be selected according to characteristics of the PCoA and height of the BX.