Role Of High Thoracic Epidural Anesthesia Plus Nimodipine In The Rabbit Model Of Cerebral Vasospasm Following Subarachnoid Hemorrhage

OBJECTIVE To compare the efficacy of high thoracic epidural anesthesia (HTEA) and nimodipine in preventing cerebral vasospasm (CVS) following subarachnoid hemorrhage (SAH) in rabbits. And to investigate the role of high thoracic epidural block plus nimodipine in the rabbit model of cerebral vasospasm following subarachnoid hemorrhage.METHODS The HTEA model at T6～7 epidural space was established in 90 rabbits, who were randomly assigned to 5 groups of 6 rabbits each, i. e. the sham-operated group(S), Control group (Con), HTEA treatment group (HS),Nimodipine treatment group(NS) and HTEA plus Nimodipine treatment group(HNS). SAH was developed by two injection of autoblood into the cistern magna (0.5 ml/kg), Transcranial Doppler ultrasonography was used to detect the basilar artery mean flow velocity (Vm) 1, 7 and 14 days after SAH. Serum S100B and NSE concentration is determined by ELISA in 1, 7,14 days after SAH.The changes in histological morphology of the basilar artery were observed under a light Microscope,and TUNEL staining were conducted on basilar arteries collected, Bcl-2 and Caspase-3 were measured in the endothelial cells of basillary artery by immunohistochemistry.RESULTS Compared to S group, The Vm and Vp of the basilar artery , Serum S100B and NSE were found to be elevated, the lumina of the basilar arteries became narrow and the walls of the basilar artery were thick (P<0.05); The Vm and Vp of the basilar artery, Serum S100B and NSE in the control group was significantly faster than that in the treatment groups (P<0.05); There were insignificant difference in the Vm and Vp of the basilar artery and Serum S100B and NSE among the treatment groups. Pathological observations showed that in the control group the lumina of the basilar arteries was narrower and the basilar artery walls were thicker than those in the three treatment groups, Moreover, the apoptosis index of endothelial cells was also significantly increased,Bcl-2 were down-regulated and Caspase-3 were up-regulated in other groups; but there were no significant difference between the Nimodipine and HTEA treatment groups,And Compared to Con,NS and HS group, the results were opposite.CONCLUSION This study demonstrates that prophylactic continuous HTEA or nimodipine equally prevents SAH-associated CVS in an animal model. More over,it suggests that continuous HTEA plus nimodipine play a beneficial role to vasospasm development, possibly through protecting endothelial cells and up-regulating Bcl-2, down-regulated Caspase-3.