The relationship between hyperperfusion and temporary clipping was evaluated to determine the safe limit for the duration of temporary clipping in aneurysm surgery. Twenty-one patients surgically treated for a ruptured aneurysm were examined using xenon-enhanced computed tomography on postoperative days 4 to 13. Eight of the 16 patients undergoing temporary clipping had focal hyper perfusion; whereas the five patients without temporary clipping had no hyperperfusion.Mean total temporary clipping time in patients with hyperperfusion was significantly longer than that in pa tients without (31.9 vs. 13.9 minutes, p = 0.0157) and mean maximum single temporary clipping time in patients with hyperperfusion was also significantly longer than in patients without (18.4 vs. 8.6 minutes, p = 0.0313). Moreover, cerebral infarction was related to hyperperfusion (p = 0.0027). These results support the hypothesis that temporary clipping during aneurysm surgery causes post operative hyperperfusion and cerebral infarction. Temporary clipping may be harmful when per formed for more than 20 minutes of total duration, since postoperative hyperperfusion was seen under this condition.

No abstract