Experimental Study Of Lumbar Subarachnoid Continuous Drainage On Cerebral Vasospasm Following Subarachnoid Hemorrhage

Objects: To investigate the effect and mechanism of lumbar subarachnoid space continuous drainage on cerebral vasospasm(CVS) following subarachnoid hemorrhage(SAH),and further explore the mechanism of CVS.Methods: SAH model was achieved by cisternal magna twice injections of autolugous blood.Thirty mongrel dogs presented with SAH were randomly divided into five groups: early-drainage group(2h),later-drainage group(5d),early-puncture group(2h),later-puncture group(5d) and control group.Either lumbar puncture group or drainage group was further divided into two groups according to the starting time of puncture and drainage. The lumber puncture two groups started to puncture and exclude blood cerebral spinal fluid(CSF) 2 hours later following the second injection and on day 5 respectively,while the drainage two groups started to drainage at the same time.The content of ET-1 in CSF and plasma was detected by immunoradioactivity and the content of NO in CSF and serum was measured by activated cadmium reduction method.The degree of CVS was determined through angiography to observe the reduction of basilar artery diamiter(％RBAD).The interface was analyzed between the changes of CVS and RBC count in CSF,contents of ET-1 and NO in CSF and blood.Results: ①Cases and degree of CVS:there were six cases with CVS(6/6) and the maximum of CVS degree was 48±10 in control group.Lumber puncturegroups:there were 6 cases with CVS(6/6) and the degree of CVS was 33±7 in early puncture group.In later puncture group,there were also 6 cases with CVS(6/6) and the degree of CVS was 42±10.There were 3 cases with CVS in this group(3/6) relieved on day 14.Drainage group:3 cases with CVS(3/6) and the maximum degree was 20±5 in early drainage group.In later drainage group,all of the 6 cases of experimental dogs presented with CVS and the maximum degree of CVS was 30±5.On the 14th day,there were 5 cases with CVS relieved(5/6).②Content changes of ET-1 in CSF and plasm:the contents of ET-1 following SAH either in CSF or in plasm at different stages were higher than that before injection of blood.The drainage group had a significant lower content of ET-1 in CSF than that of puncture and control group.③Content changes of NO in CSF and serum:the contents of NO in CSF following SAH at different stages were lower than that before injection of blood and only at certain stages the contents of NO in serum were lower than the normal content.The drainage group had a relatively higher content of NO than that of puncture and control group.④The large amount of RBC in CSF would lead to the increase of ET-1 and the decrease of NO in CSF which should further make the degree of CVS more serious.⑤Lumber subarachnoid space continuous drainage in early stage had a lower incidence of CVS and a more slight severity of CVS.Conclusions: The RBC and its decomposed substances may be one of the main reasons of CVS.The CVS related to the increased content of ET-1 and the decreased content of NO in CSF and may not relate to the changes of ET-1 and NO in blood.Lumbar subarachnoid space continuous drainage may prevent and reverse the CVS by changingthe contents of ET-1 and NO in CSF.Early lumbar subarachnoid space continuous drainage should be presented with better consequence.