Relation between angiographic cerebral vasospasm and regional CBF in patients with SAH.

The relation between angiographically determined cerebral vasospasm following a subarachnoid hemorrhage and regional cerebral blood flow (CBF) was studied in 63 investigations of 45 patients. The CBF was measured using the intra-arterial 133-Xe clearance technique within one hour of angiography. A positive correlation between regional CBF and diameter of major supplying vessel was observed. However, in the 13 cases with focal vasospasm the reduction in CBF was global and not restricted to the area of the spastic vessel. The cerebral oxygen extraction was reduced but independent of the degree of vasospasm, speaking against vasospasm as the cause for the reduction in CBF. The observed association between reduction in CBF and vasospasms could be caused by a common factor responsible for development of both. Thus, it is proposed that the amount of blood escaping at time of aneurysm rupture determines 1) the amount of reduction in cerebral oxygen uptake and thereby the reduction in CBF and 2) the degree of vasospasm. If so a correlation, yet not causal, between reduction in CBF and degree of vasospasm, will be observed.