Extracranial Carotid-Vertebral Bypass for Endovascular Access to Complex Posterior Circulation Aneurysms

Abstract

BACKGROUND: Endovascular embolization is a desirable treatment option for complex posterior circulation aneurysms, particularly recurrent aneurysms or those in difficult-to-access surgical locations. However, endovascular access is occasionally prohibited by proximal vertebral artery (VA) occlusion or vessel tortuosity. One strategy in such instances involves creation of an extracranial bypass conduit to the distal VA. OBJECTIVE: To describe a novel strategy to allow for endovascular treatment of aneurysms at high risk for direct surgery. METHODS: Three cases of carotid-VA bypass performed to provide endovascular access to posterior circulation aneurysms were identified. The clinical indications, radiographic characteristics, operative technique, and outcomes were reviewed. RESULTS: Indications for bypass were previously clipped recurrent basilar tip aneurysm, previously coiled midbasilar aneurysm with compaction requiring stent placement, and distal intracranial VA aneurysm with iatrogenic vertebral dissection/occlusion after initial coil attempt. In all cases, routine endovascular access for primary or stent-assisted coiling was prohibited by VA tortuosity. Bypass with the use of interposition saphenous vein grafts was successfully performed to the C1-C2 region of the V2 segment without complications. The bypass was followed by successful endovascular treatment in all cases 2 to 6 weeks after surgery. In 1 patient, 2 recurrent treatments through the graft were subsequently performed for coil compaction. CONCLUSION: Extracranial carotid-VA bypass can be a valuable tool in the management of complex posterior circulation aneurysms. It is a safe and efficacious technique providing a conduit for repeated access to the posterior circulation in patients with otherwise prohibitive vertebral anatomy.