The effect of removal of subarachnoid blood clots on the prevention of delayed ischemic deficit was evaluated in 242 patients with ruptured supratentorial aneurysms, which were clipped within 48 hours after subarachnoid hemorrhage (SAH) via a pterional approach. They were all classified preoperatively in Grade 1 to 4 according to the system of Hunt and Hess. Severe delayed ischemia which caused permanent disability or death occurred in 32 (30.8%) of 104 Group A patients in whom blood clots only adjacent to the aneurysms were removed. It occurred in 17 (12.3%) of the other 138 Group B patients in whom subarachnoid clots were more radically removed along the arteries around which the arachnoid membrane could be opened as extensively as possible at least by way of a unilateral pterional approach. In Group B, the clots around the middle cerebral artery (MCA) ipsilateral to approach were most extensively removed up to the distal portion beyond the trifurcation. The incidence of delayed ischemia in the area of the MCA ipsilateral to approach was 22.1% in Group A and 5.8% in Group B. Its incidence in the area of the other arteries than the MCA ipsilateral to approach was 8.7% in Group A and 6.5% in Group B. The results in this study indicate that extensive removal of subarachnoid clots decreases occurrence of delayed ischemia due to vasospasm.
