Induced-Wedge Technique to Improve Liquid Embolic Agent Penetration into Spinal Dural Arteriovenous Fistula

Objective To promote embolization of spinal dural arteriovenous fistula (SDAVF) with a small long tortuous feeder that may impede successful application of an embolic agent. Methods An induced-wedge technique was developed in which blood flow was blocked by coiling at the proximal part of the microcatheter for secure injection of N -butyl cyanoacrylate. We used this technique in 11 patients with SDAVF (male/female ratio, 8:3): 7 thoracic, 2 lumbar, 1 sacral, and 1 cervical. Clinical outcome was evaluated by the Aminoff-Logue Disability Scale. Results Penetration of embolic agent through the fistula into the vein was complete ( n  = 5), nearly complete (no penetration of embolic agent into the vein but no residual fistula on 3 adjacent selective angiograms; n  = 4), or partial (embolization with a small residual filling of the draining vein; n  = 2). All patients improved neurologically during follow-up (median, 18 months; range, 7–37 months) and achieved complete recovery. Of the 2 patients who obtained partial obliteration, one showed disappearance of the residual lesion on angiography 21 months later and the other achieved complete results after repeat embolization. Conclusions The induced-wedge technique can improve SDAVF embolization by providing better penetration of the liquid embolic agent to the fistula and vein.