A New Window for the Treatment of Posterior Cerebral Artery, Superior Cerebellar Artery, and Basilar Apex Aneurysm: The Expanded Endoscopic Endonasal Approach

Objective: Since the inception of endoscopic skull base surgery, it has continued to evolve through the advent of new technology and surgical corridors. Currently, the expanded endoscopic endonasal approach has given us access to areas of the skull base previously thought not to be approachable through an endonasal technique. Basilar apex aneurysms are the most commonly reported aneurysms in the posterior arterial circulation and have been associated with a higher risk of bleeding, mortality, and morbidity than seen in other locations. In addition, superior cerebellar and posterior cerebral artery aneurysms are seen less frequently, but they can be associated with basilar apex aneurysms. Different surgical approaches and endovascular interventions have been described for the management of these aneurysms, but they can sometimes be associated with high clinical morbidity. The goal of this is study was to explore the feasibility of an endoscopic endonasal transclival approach to treat aneurysms arising in these vessels.

Study Design: This is a comparative anatomic study on human cadaveric heads.

Methods: A total of 15, latex-injected adult cadaver heads were dissected using the endoscopic endonasal transclival approach. The anatomical boundaries and operative technique have been described, along with the degree of surgical exposure of each artery attained, measured with a 10-cm surgical ruler. Using extended vascular clip applicators, we also investigated the feasibility of clipping these vessels through an endonasal technique.

Results: We were able to expose both posterior cerebral arteries with an average length of 0.67 ± 0.2 cm on the right side and 0.59 ± 0.2 cm on the left side. Both right and left superior cerebral arteries were exposed with an average length 0.6 ± 0.2 cm and 0.7 ± 0.3 cm, respectively. We safely identified cranial nerve (CN) III running between the posterior cerebral and superior cerebellar arteries in all specimens. The length of the basilar artery exposed was on average 2.6 ± 0.3 cm. The distance from the nasal vestibule to the posterior cerebral artery, superior cerebellar artery, and basilar apex was approximately 10 cm with a standard deviation of ± 0.7, 0.6, and 0.8 cm, respectively. We were able to safely place clips in the posterior cerebral artery, superior cerebellar artery, and basilar apex using the extended clip applicator with minimal alteration of the surrounding normal tissue.

Conclusion: The endoscopic endonasal transclival approach represents a direct anatomical route to the posterior cerebral artery, superior cerebellar artery, and basilar apex. We believe that this approach is a feasible surgical corridor to treat aneurysm arising in these vessels through the use of extended vascular clip applicators.