Intentional staged embolization via the “highway bypass” using a radial artery graft for a large posterior circulation aneurysm: illustrative case

BACKGROUND The presence of significant tortuosity in access routes to aneurysms can interfere with catheter guidance and manipulation and significantly impact treatment strategies. OBSERVATIONS In this report, the authors combined intentional staged aneurysm embolization with the construction of a new direct access route, which they call a “highway bypass,” for a symptomatic posterior circulation cerebral aneurysm that was difficult to access with a catheter. Notably, the highway bypass is used for catheter passage, and technical tips should be considered. The patient had a symptomatic unruptured cerebral aneurysm in the first segment of the left posterior cerebral artery with bilateral internal carotid artery occlusion and severe tortuosity of the bilateral vertebral arteries. The highway bypass using a radial artery graft was performed in the first stage; in the second stage, the aneurysm was accessed using the graft, and embolization was performed. The catheter was passed through the graft without complications. The aneurysm was successfully embolized, no ischemic lesions were found in the postoperative images, and the patient was discharged without worsening neurological findings. LESSONS Intentional staged aneurysm embolization combined with the highway bypass effectively treats aneurysms that are difficult to access. Anastomoses should be designed to allow catheters to pass through the graft.