Contribution of deep cerebral venous anomaly to the emergence of non-aneurysmal SAH as opposed to aneurysmal SAH.

BACKGROUND: The exact reason of non-aneurysmal SAH is an enigma.

OBJECTIVE: To identify if type III deep cerebral venous drainage is exclusively prevalent in patients with non-aneurysmal SAH and to enumerate the predictors of poorer outcome in these patients.

PATIENTS: All patients of age >18 years, presented at our centre with spontaneous SAH on NCCT head and were divided into two groups, aneurysmal and non-aneurysmal SAH after 4-vessel DSA. Based on the deep venous drainage pattern on both sides, basal venous drainage was found and classified into three types: type I, type II, and type III. The three groups were pitted against one another. Regression analysis was performed to predict the occurrence of nonaneurysmal - SAH with different types of basal vein.

RESULTS: There were 100 non-aneurysmal SAH cases and 103 aneurysmal SAH cases. The mean age of presentation was 47.8 ± 13.55 years with slight male predominance (52%). The patients with type III venous drainage have 2 times more risk of developing non-aneurysmal SAH (95%CI = 1.21 - 4.31) as compared to those with type I venous drainage. On multivariate analysis, type III basal venous drainage, worse Hunt and Hess grade at presentation, extensive bleeding were predictors of an adverse outcome.

CONCLUSION: The presence of type III venous distribution is associated with a twofold increase in the probability of having non-aneurysmal SAH, as well as a threefold increase in the risk of developing poorer neurological sequelae.