Experimental study of rapid versus slow sagittal sinus occlusion in dogs

Background: Clinical, radiological, postmortem and experimental studies are not enough for the definition of pathophysiological differences between rapid and slow-progressing cerebral venous system obstruction. Aims: An experimental study was conducted to set some physiopathological differences between rapid and slow occlusion of the superior sagittal sinus. Settings and Design: Eighteen dogs categorized into 3 groups were chosen as test subjects. The three groups were the rapid occlusion, slow occlusion and the control study groups and each group had six subjects. Material and Methods: Intracranial pressure values, histopathological findings, and the degree of cerebral edema formation, estimated by measuring the water content ratio of the brain and the angiographic results in the 2 different groups of subjects that underwent rapid and slow superior sagittal sinus obstruction were compared with that of the control subjects. Statistical Analysis: Statistical analysis was performed using GraphPad Prisma V.3 statistical software. Variables of the 3 groups were compared using non-parametric Kruskal Wallis ANOVA test and multiple comparisons were made using Dunn's multiple test. The comparison of initial and terminal 1ntracranial pressure values obtained before and after the sinus occlusion, was made using the Wilcoxon test. A probabability value of less than 0,05 was regarded as significant. Results and Conclusions: Comparison of the water content ratio of the brain in the 3 groups, the difference between the initial and terminal intracranial pressure values of the rapid occlusion study group, and the difference between the terminal intracranial pressure values of the 3 groups was statistically significant (P<0,05). Dunn's Multiple Comparison Test yielded significant differences in the water content ratio of the brain and in the intracranial pressure values between the rapid occlusion study group and the control group (P<0,05). Moreover, histopathological and radiological examination disclosed more prominent brain edema findings, and less apparent collateral venous flow in the rapid occlusion study group than in the slow occlusion one. To conclude, the clinical severity of sinus occlusion seems directly related to the quickness of the occlusion and the capacity of the collateral venous system.