Preventive Effects of High Thoracic Epidural Block on Acute Cerebral Vasospasm Following Subarachnoid Hemorrhage in Rabbits

Objective To investigate the preventive effects of high thoracic epidural block (HTEB) on acute cerebral vasospasm (CVS) following subarachnoid hemorrhage (SAH) in rabbits. Methods The HTEB model at T6~7 epidural space was established in 30 rabbits, who were divided into 3 groups of 10 rabbits each, i. e. the normal group, SAH group and HTEB group. CVS was developed by injection of non-anticoagulant autologous arterial blood (0.5 ml/kg) into the cisterna magna in SAH and HTEB groups where injection of the autologous arterial blood into the cistern magna was performed 30 minutes after HTEB. Transcranial Doppler ultrasonography was used to detect the basilar artery mean blood flow velocity (Vm) 1 day after SAH. The changes in pathohistology and calibre of the basilar artery were observed under a light Microscope. Results The Vm of the basilar artery in SAH group increased significantly compared to the normal group (P0.01). The Vm in HTEB group was significantly slower than that in SAH group (P0.05). Pathological observation showed that the lumina of the basilar arteries became more narrow in SAH group and the pathologic changes in the basilar artery walls was more serious than those in HTEB group. Conclusion HTEB used before SAH has the preventive effects on acute CVS in rabbits with SAH.