C2-P2 Bypass: Technical Assessment of Petrous Carotid Artery to Posterior Cerebral Artery Interpositional Bypass Through the Combined Transcochlear-Subtemporal Approach as a Part of Microsurgical Treatment for Dolichoectatic Vertebrobasilar Artery Aneurysms

BACKGROUND AND OBJECTIVES: Managing dolichoectatic vertebrobasilar artery aneurysms requires a multifaceted approach. Revascularization of the posterior circulation with a high-flow bypass is part of the flow reversal paradigm. Performing a robust high-flow bypass and addressing the aneurysm through the same approach smooths the operative intervention. This study assessed the anatomic feasibility of accessing the basilar trunk and aneurysm simultaneously to revascularize the posterior circulation using a petrous internal carotid artery (pICA)-posterior cerebral artery (PCA) interpositional bypass through a complete petrosectomy. METHODS: Six embalmed cadaveric heads (12 sides) underwent a combined extended transcochlear-subtemporal approach to expose the pICA and P2 PCA. A pICA (side-to-end) graft (end-to-side) PCA bypass was attempted. The lengths of the vessels relevant to the bypass and the graft length were measured. RESULTS: The bypass was successfully completed in all specimens. The mean exposed lengths of the pICA and PCA were 21.3 and 20.0 mm, respectively. The mean length of the perforator-free zone on PCA was 11.2 mm. The mean length of the interposition graft was 36.6 mm. CONCLUSION: The transcochlear approach can be used to expose the pICA as a donor for a high-flow bypass to the PCA as part of the treatment paradigm for dolichoectatic vertebrobasilar artery aneurysms. Careful patient selection and extensive knowledge of skull base anatomy are mandatory for this strategy.