Duplication of the distal end of the left vertebral artery with fenestration of the right posterior cerebral artery.

The vertebrobasilar system (VBS) consists in the intracranial parts of the vertebral arteries (VAs), the basilar artery (BA) and its branches. The presence of a duplication at the level of the intracranial segment of VA (V4) is generally an incidental finding, but may be associated with aneurysms or arteriovenous malformations. We present an extremely rare case of duplication of the distal end of the left vertebral artery, associated with fenestration of the right posterior cerebral artery. The distal end of the left VA was duplicated into two arms (the right with a length of 5.5 mm and a diameter of 2.3 mm that connected with the contralateral VA; and the left with a length of 11.0 mm and a diameter of 1.6 mm, which connected more distally with the BA). The right posterior cerebral artery (PCA) had a fenestration in the posterior segment of the posterior communicating part (P2), with a length of 6.8 mm.