Research on the pathogenesis of cerebral vasospasm following subarachnoid hemorrhage

? Objective:To further study the pathogenesis of cerebral vasospasm following subarachnoid hemorrhage to serve the clinical treatment.Methods:In this research,canine double SAH model was established by two successive injections of cisternal blood administered 72 hours apart.Angiogram,vessel function,free radical activity and pathological changes in vessel wall survived until sacrifice on the 7th day after first injection were studied in all animals ( n =9 for hemorrhage,and n =5 for control group).Results:Angiograms of basilar arteries (BA) showed:At 30th minute,1st hour and 7th day after first injection,an average arterial diameter was 68.3%±15.6% ( P <0 01),66.8%±13.8% ( P <0 01) and 52.7%±19% ( P <0 001) respectively.At 30th minute after nimodipine (0.1 mg/kg,intravenously, n =13) was given at 30th minute and on 7th day after first injection of blood,the BA′s diameter changed from 59%±13.6% to 96.2%±12.1% ( P <0 01) and 60.6%±13.6% to 72.4%±19.6% ( P >0 05) of the basiline respectively.The preventive consecutive application of nimodipine (40mg by oral administration,every 6 hours untill the last day of study, n =7) had no effects on chronic CVS.Rings of basilar arteries obtained from SAH group contracted much more weakly than those from control group in response to vasoconstrictors ( P <0 01).MDA of BA′s wall was much more in SAH group than in control group ( P <0 01),and MDA content was consistent with the vessel wall injuries.The pathological study of BA′s wall confirmed degenerative changes in the tunica intima and media,subendothelial and medial thickening,partial myonecrotic changes,and the leukocytic infiltration in the tunica adventitia.Conclusions:①Nimodipine can reverse acute vasospasm,but it shows no effects on chronic vasospasm.②High concentration of lipid peroxides in chronic constricted vessel wall relates to vessel wall′s damage.③Chronic CVS is demonstrated in structural constriction involved in vessel wall′s damage following SAH. 〔