Non-aneurysmal subarachnoid hemorrhage: Is the deep venous system the hidden culprit?

The exact cause of bleeding in non-aneurysmal sub-arachnoid hemorrhage (SAH) is yet to be established. The present study intends to evaluate the morphological variants of deep cerebral venous drainage, especially basal veins of Rosenthal (BVR), and to correlate if such a venous anomaly is associated with increased incidence of non-aneurysmal SAH.

A prospective analysis of all the patients of age more than 12 years with spontaneous non-aneurysmal SAH and undergone 4-vessel DSA for the diagnosis of the source of bleeding was included in the study (n = 59). The anatomy of the basal venous distribution was evaluated and was divided into 3 different types, namely normal (Type A), normal variant (Type B), and primitive (Type C), based on DSA findings. The follow-up of these cases was noted. The three groups were compared with one another.

The median age of presentation was 51 years with slight male predominance (52%). Primitive venous drainage was associated with a poorer grade at presentation (p = 0.002), more severe bleed (p = 0.001), vasospasm (p = 0.045), and a poorer outcome at 6 months (p = 0.019). Hydrocephalous and vasospasm were seen in patients with primitive venous drainage. On multivariate regression analysis for poorer outcome, it was observed that a worse grade at presentation, extensive bleed, primitive venous drainage are independent predictors of an adverse outcome.

The presence of primitive venous drainage has a linear relationship with the development of non-aneurysmal SAH with multi-cisternal hemorrhage, worse grade at presentation, and unfavorable outcome.