Internal carotid artery-to-posterior cerebral artery bypass for revascularization of the brainstem.

We describe a novel bypass technique used to revascularize the brainstem by anastomosing the internal carotid artery (ICA) to the posterior cerebral artery (PCA) using a radial artery graft, effectively creating a functional alternative to the posterior communicating artery. A 72-year-old male patient presented with rapidly progressive neurological symptoms attributable to brainstem compression; imaging showed a giant, fusiform, partially thrombosed, vertebrobasilar artery aneurysm. An Alcock's test revealed no significant collateral circulation from the posterior communicating arteries. To revascularize the top of the basilar artery, we performed an ICA-to-PCA bypass using a radial artery interposition graft. Specifically, we used the radial artery graft to connect the supraclinoid ICA to the P2 segment of the PCA. The basilar artery was subsequently occluded during the same operation by placing a clip below the superior cerebellar arteries. Although the bypass remained patent, the patient suffered an acute thrombosis of the aneurysm, resulting in fatal pontine infarction.