[Therapeutic occlusion of unilateral vertebral artery for unclippable aneurysms; special reference to postoperative brainstem ischemia].

Seven cases of unclippable vertebral artery aneurysms (3 dissecting, 1 fusiform, 2 saccular and 1 giant) are reported. Five of these had subarachnoid hemorrhage, one showed mass effect and the other was found incidentally. Trapping of the involved portion of the vertebral artery was performed in 4 cases, proximal clip occlusion in 2 and proximal balloon occlusion in 1. There were no operative deaths and no rebleeding, but brainstem ischemia developed in 4 cases, two being transient and two permanent. The ischemic complications were possibly due to; (a) hypoperfusion in the transient cases and (b) thromboenbolism, from the partially thrombosed giant aneurysm or thrombosis of the cul-de-sac vertebral artery, in the permanent ones. Preoperative temporary vertebral artery occlusion with an inflatable balloon or postoperative anticoagulant therapy should be considered in the management protocol.