High-flow bypass for giant dolichoectatic vertebrobasilar aneurysms: illustrative cases.

Background: Giant fusiform dolichoectatic vertebrobasilar artery aneurysms are challenging lesions with a poor natural history. When there is progressive brainstem compression from these lesions, endovascular treatment can be insufficient, and bypass surgery remains a possible salvage option. High-flow bypass surgery with proximal occlusion can potentially arrest aneurysm growth, promote aneurysm thrombosis, and reduce rupture risk. The authors describe their experience in two patients with giant fusiform dolichoectatic vertebrobasilar artery aneurysms treated with high-flow bypass.

Observations: Both patients presented with enlarging giant dolichoectatic vertebrobasilar aneurysms causing symptomatic brainstem compression. The authors performed staged treatment involving high-flow bypass from the external carotid artery to the posterior cerebral artery using a saphenous vein graft, Hunterian proximal vertebrobasilar occlusion, and finally posterior fossa decompression with or without direct aneurysm thrombectomy and debulking. Postoperative angiography revealed successful flow reversal, aneurysm exclusion, and no brainstem stroke. Clinically, one patient had improvement in their modified Rankin Scale (mRS) score from 3 preoperatively to 1 at 12-month follow-up. The second patient had a deterioration in their mRS score from 4 to 5 at 12-month follow-up.

Lessons: High-flow bypass strategies remain high risk but can be a viable last resort in patients with neurological deficits and enlarging giant fusiform dolichoectatic vertebrobasilar artery aneurysms.