Abstract T P244: Correlation between Vasospasm and Microcirculatory Disturbance in Early and delayed Phase following Experimental Subarachnoid Hemorrhage

Background & Objectives: Role of cerebral vasospasm in cerebral microcirculatory disturbance after subarachnoid hemorrhage (SAH) remains to be elucidated. This study investigated the correlation between changes of cerebral microcirculation and time course of arterial narrowing after SAH using rabbit cisterna magna double-blood injection model. Methods: Using 256-multidetector-row computed tomography (CT), CT angiography and CT perfusion were repetitively performed at 0, 1, 6, 24, 48 hours after initial hemorrhage for early changes observation group (ECOG; n=8), and on days 0, 3, 5, 7 for delayed changes observation group (DCOG; n=8). Regional cerebral blood flow (rCBF), cerebral blood volume (CBV), mean transit time (MTT) and mean cross-sectional area of basilar artery (BA) were evaluated at each time point. Results: In ECOG, BA transiently narrowed immediately after SAH and progressively narrowed again after 6 hours. CBV and rCBF were transiently decreased immediately after SAH and restored, and then progressively increased after 6 hours. MTT was transiently prolonged immediately after SAH and gradually restored over 24 hours. In DCOG, basilar arterial narrowing reached a peak on day 5 and improved after day 7. CBV and rCBF were persistently decreased after day 3, while MTT was prolonged after day 5. In both observation groups, there were no significant differences in CTP parameters between in perfusion territory of BA and that of non-BA. Conclusions: Presumably, in this model, delayed cerebral ischemia is caused by the cerebral microcirculatory disturbance which is regulated by independent mechanisms from vasospasm of major arteries both in the early phase and delayed phase following SAH.