Experimental vasospasm, acute and chronic, due to blood in the subarachnoid space

✓ This investigation on monkeys provides arteriographic and other evidence that blood, in the absence of evident mechanical stimulation or injury to intradural arteries, will, when injected into the anterior cervical subarachnoid space through a catheter, consistently cause acute and chronic vasospasm of the intradural arteries, presumably where they are contacted by blood. Evidence indicates that vasoconstrictor agents or factors in fresh blood cause the vasospasm, since similar subarachnoid injection of saline or clear serum did not cause vasoconstriction. Other circumstances involving mechanical or other factors, such as vessel injury, may contribute to the length and severity of the vasospasm, but whether they have an etiological role needs further study.