Abstract TMP108: Absence of Cortical Microvessel Spasm During Large Vessel Spasm Following Experimental Subarachnoid Hemorrhage

Abstract

Introduction: A significant portion of the morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH) is due to delayed ischemic neurological deficits (DIND). Although large vessel vasospasm has been implicated as a cause of DIND, the presence of such spasm is not always correlated with DIND. In the present experiment we examined the cortical microvasculature in awake mice after SAH in an experimental model typically associated with large vessel vasospasm. Methods: Twenty adult mice underwent cisterna magna (CM) injection of 60ul syngenic donor blood or artificial cerebrospinal fluid (aCSF). The mice were perfused at 72 hours, and Circle of Willis (COW) vessel diameters were measured. In a separate experiment, polished and reinforced thinned skull cranial windows were created in 10 mice that then underwent CM blood or aCSF injection. Cortical microvessels were measured in living, awake mice in the postoperative vasospasm period using two photon laser scanning microscopy. Results: A pairwise comparison of COW vessels revealed a statistically significant difference in vessel diameter between the experimental and control groups at each of the sites measured (ACA, P=0.0012; MCA, P=0.0259; Pcom, P=0.0053). In the second experiment, there were no significant differences in cortical microvessel diameter between the experimental and control groups. Conclusions: This study represents the first report of in vivo imaging of cortical microvessels during large vessel spasm following SAH. In a CM injection SAH model, we observed significant large vessel spasm but no cortical microvessel spasm. These results may have important implications for understanding the mechanisms of DIND.