RAPID SPONTANEOUS DIMINUTION OF CISTERNAL BLOOD ON COMPUTED-TOMOGRAPHY IN PATIENTS WITH SUBARACHNOID HEMORRHAGE

BACKGROUND purpose of this study is to investigate whether rapid spont aneous diminution of cisternal subarachnoid hemorrhage (SAH) alleviate s vasospasm in the corresponding arterial territory, METHODS The subje cts were 103 patients in whom initial computed tomography scans were p erformed within 24 hours after SAH and repeated within 72 hours. We an alyzed the effect of diminution of cisternal SAH on vasospasm in 16 si tes in each patient. Of the total 1642 cisterns, SAH was found in 1362 (83%), of which 539 (40%) had a decrease in SAH. The highest diminuti on rate was 64% in quadrigeminal cistern, and the lowest rate was 27% in frontal interhemispheric fissure (IHF). In basal frontal IHF, both the incidence of diminution of SAH and its degree were significantly l ower in patients with ruptured anterior cerebral artery aneurysms than in those with other site aneurysms, while in suprasellar cisterns, sy lvian stems, and sylvian fissures, diminution of SAH was not affected by the side of ruptured aneurysms. The diminution of SAH in basal fron tal IHF and sylvian stems was associated with less vasospasm in adjace nt arteries. CONCLUSIONS We concluded that in patients with SAH, rapid spontaneous diminution of cisternal blood, which is affected by sever al factors, makes vasospasm in the corresponding arterial territory le ss likely.