Treatment of unclippable giant posterior cerebral artery aneurysms with detachable balloons--report of three cases.

Three patients presented with rare giant posterior cerebral artery aneurysms, clinically manifesting as cerebral ischemia, mass effect, and subarachnoid hemorrhage. All aneurysms were partially thrombosed, originated at the P2 segment, and possessed broad necks. Surgical neck clipping was difficult but proximal occlusion of the parent artery was feasible. Aneurysm occlusion sparing the parent artery was attempted in all cases, but failed because the detachable balloon did not successfully block the aneurysmal neck. All patients tolerated test occlusion at the P2 segment, so the parent artery was occluded proximally with detachable balloons, leaving the important perforating arteries unaffected. Two transient ischemic attacks were associated with the procedure. Where surgical treatment is unusually difficult, and proximal ligation or trapping just feasible, embolization with detachable balloons is an acceptable substitute.