Introduction: We quantified the surgical exposure of the basilar apex through the optico-carotid window (OCW) and the carotid-oculomotor window (COW), before and after mobilization of the internal carotid artery (ICA) and division of the posterior communicating artery (PCoA).
Methods: Eleven silicone-injected cadaveric heads were dissected bilaterally. The surgical dissection was divided into four major steps: 1) supraorbital modified orbitozygomatic craniotomy; 2) mobilization of the ICA after drilling out the anterior clinoid process intradurally and, cutting the distal dural ring 3) drilling out the posterior clinoid process and dorsum sellae; 4) dividing the PCoA at the posterior third of the PCoA. A frameless navigational system was used to quantify the surgical exposure area of the basilar apex through the OCW and COW.
Results: Total surgical area increased significantly from steps: 1-4 (p< 0.001), in both OCW and COW groups. Overall there was a larger total surgical area obtained in the COW when compared to the OCW (p= 0.010). ICA mobilization increased the surgical area of temporary (p< 0.001) and permanent (p<0.003) clip application in both windows. The division of PCoA significantly increased overall surgical area for permanent clip application (p<0.003). Compared to the OCW, the COW had a significantly increased change in the area for permanent clip application in the low lying group (p = 0.031). In case of short hypoplastic PCoA (n = 8), the area for the application of the permanent clip significantly increased in both the OCW (p= 0.045) and COW (p= 0.003), and there was also a significant greater change in the COW than in the OCW (p= 0.031).
Conclusions: : When approaching the basilar apex via the pterion route, the appropriate surgical step and window may be selected according to characteristics of the PCoA and height of the basilar apex.
Patient Care: This will enable a surgeon to plan the best corridor to take in order to clip a basilar apex aneurysm. It will also allow a surgeon to know exactly how much area he/she would be able to gain based on what corridor is taken to reach the interpeduncular fossa.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of internal carotid artery mobilization and posterior communicating artery division, with respect to increasing the surgical exposure to the interpeduncular fossa, 2) Discuss in small groups, the significance of dividing the posterior communicating artery, 3)Identify what circumstances, these techniques may be useful.