label: Basilar artery fenestration
label_lc: basilar artery fenestration
description: "A fenestration affecting the basilar artery. Basilar fenestration typically occurs at the lower end of the basilar artery just as the vertebral arteries join Fenestrations of intracranial arteries are segmental duplications of the lumen into two distinct endothelium-lined channels, which may or may not share their adventitial layer. They can range from a small focus of divided tissue to long-segment duplication. Fenestrations are the result of partial failure of fusion of paired primitive embryologic vessels or incomplete obliteration of different anastomosis in a primitive vascular network. The association of fenestrations with aneurysms has been suggested in many small case series, though the exact relationship is not well defined."