Regional cerebral blood flow (rCBF) was estimated by the Xe133 venous method in 37 preoperative patients with subarachnoid hemorrhage (SAH) due to rupture of a cerebral aneurysm. Daily estimates were made during first about 2 weeks after SAH (98 studies). The rCBF fell progressively with various degrees during the first 2 weeks after SAH. The marked reduction of rCBF was observed in the group of old age, hydrocephalus, severe SAH on CT scan and ruptured anterior communicating aneurysm. However, there was no significant difference of rCBF in the grade of Hunt and Hess on admission, this reason was thought not to be estimated rCBF in the grade IV and V of Hunt and Hess for the death in their way. Twenty-four of the patients were taking inhibitor of thromboxane A2 synthetase (OKY-046) for preventing of cerebral aneurysm, other 13 patients were not taking. The reduction of rCBF in the group treated with OKY-046 tend to be suppressed, comparing to it in the group with no treatment. And OKY-046 prevented the decreasing of rCBF significantly at 2 weeks after SAH.
