Factors determining the success of endovascular treatments among patients with spinal dural arteriovenous fistulas

Introduction: Despite improvements of embolization agents and techniques, endovascular treatment of spinal dural arterovenous fistula (SDAVF) is still limited by inconsistent success. The aim of embolization is to occlude initial portion of the draining vein by liquid embolic materials. This study investigates factors that contribute to the success of embolization treatments among SDAVF patients. Methods: We performed a retrospective analysis on consecutive SDAVF patients who received N-butyl cyanoacrylate (NBCA) glue embolization between January 1992 and June 2012. Univariable and multivariable logistic regression analyses were performed to calculate the probability of successful draining vein occlusion for variable procedure-related factors. Results: We attempted endovascular approach as the first intention treatment in 66 out of 90 consecutive patients. Among them, a total of 43 NBCA glue injections were performed in 40 patients. Successful embolization was achieved in 24 patients (60 %). In multivariable analyses, antegrade flow during microcatheter test injection (OR 13.2, 95 % CI 1.7 to 105.4) and use of glue concentration ≥30 % (OR 0.1, 95 % CI 0.01 to 0.8) were detected as significant positive and negative predictors of successful venous penetration, respectively. With persistent antegrade flow, the success rates using a glue mixture of more than 30 % dropped significantly from 85.0 to 42.9 % (p = 0.049). If contrast stagnated during microcatheter injections, success rates were low regardless of glue concentrations. Conclusions: Presence of antegrade flow toward the draining vein and injection of NBCA glue less than 30 % are associated with higher chance of draining vein penetration and, therefore, successful endovascular SDAVF obliteration.