Effect of rapid spontaneous diminution of subarachnoid hemorrhage on cerebral vasospasm.

In patients with subarachnoid hemorrhage (SAH), the effect of clot removal on cerebral vasospasm is still in dispute. The purpose of this study is to investigate whether rapid spontaneous diminution of subarachnoid blood alleviates vasospasm. We analyzed the effect of diminution of SAH on vasospasm in 36 patients with SAH grades III-IV who were operated on by the same surgeon by day 6 after SAH. The diminution of subarachnoid blood became more apparent with shorter interval between hemorrhage and initial computed tomography (CT) scan, with increasing patient age, and with higher SAH grades. The incidences of angiographic vasospasm grades III-IV, permanent symptomatic vasospasm, and low-density area on CT scans decreased with the increase in the degree of diminution of subarachnoid blood. Permanent symptomatic vasospasm and low-density area on CT scans were found in 5 of 9 patients with no diminution, whereas they occurred only in 5 of 27 patients with diminution (p < .05). We concluded that spontaneous diminution of subarachnoid blood in the acute stage after SAH seems to reduce the severity of vasospasm.