Thrombophilic factors and the formation of dural arteriovenous fistulas

Object Dural arteriovenous fistulas (DAVFs) are distinct neurovascular entities. Although their exact origins are unknown, venous thrombosis and venous hypertension are likely to be major inducing factors. To address the relationship between DAVFs and thrombophilic factors, the authors conducted a case-control study at a single institution and performed a metaanalysis of the literature. Methods Forty patients with DAVFs at Toronto Western Hospital were recruited to complete a questionnaire and to donate blood samples for factor V Leiden mutation and factor II G20210A mutation screening and assessment of coagulation factors. The questionnaire was designed to collect information on each participant's specific history of venous thrombosis, medications, and race. A control group of 33 healthy volunteers agreed to the same protocol. A MEDLINE search of the literature from 1966 to the present was conducted and three relevant series were found. The results of the present study were pooled with the data from the literature. Results Combining institutional results with the results from the literature yielded a total of 121 patients and 178 control group members. Thrombophilic mutations were present in 16 patients and four healthy volunteers, with an odds ratio (OR) of 4.69 for factor V Leiden (95% confidence interval [CI] 1.24–17.69) and an OR of 10.87 for the prothrombin G20210A allele (95% CI 1.32–89.51). Levels of the basic coagulation profile, fibrinogen, and factor VIII were within normal limits. Conclusions Patients with the factor V Leiden and factor II G20210A mutations are at a higher risk for DAVFs. However, because these mutations are not implicated in the vast majority of DAVFs, routine screening is not recommended.