Fig. 2.

Case 1: A tonsillomedullary segment of the left PICA was used for left OA-PICA anastomosis (a). Then the origin of the left PICA was surgically clipped (b). Follow-up angiography of the right VA performed 14 days later revealed complete thrombosis of the residual dissecting aneurysm (c: frontal view). Angiography of the left ECA showed good patency of the bypass graft (d: lateral view). OA: occipital artery, PICA: posterior inferior cerebellar artery, AN: aneurysmal dilation, VA: vertebral artery, ECA: external cervical artery.