Relationship between venous drainage subtypes and sub-arachnoid hemorrhage subtypes: a meta-analysis

Background To investigate whether associations exist between venous drainage subtypes (types I, II, and III) and the risk of subarachnoid hemorrhage subtypes. Methods Published case–control and case series from 2010 to 2014 which met all the inclusion criteria for the meta-analysis were selected and subjected to rigorous statistical analysis. Results A total of 11 studies with an overall patient population (case and controls) of 891 were involved in the study. Types I and II venous drainage had odds against peri-mesencephalic subarachnoid hemorrhage. The odds were in favor of type III venous drainage and peri-mesencephalic sub-arachnoid hemorrhage and idiopathic sub-arachnoid hemorrhage (ISAH). Conclusions Type I deep venous drainage may not be associated with the risks of peri-mesencephalic subarachnoid hemorrhage and ISAH, however, types II and III may be associated with high risk of peri-mesencephalic subarachnoid hemorrhage and ISAH, respectively.