A novel technique and new grading scale for the embolization of cerebral vascular malformations

OBJECTIVE: Effective transarterial embolization of a dural arteriovenous fistula or pial arteriovenous malformation (AVM) requires penetration of a durable occlusive agent into the fistula or AVM nidus. Cyanoacrylate glue often cannot traverse the tortuous vessels that typically supply such malformations, leading to proximal occlusion and recruitment of collateral flow. Other embolic agents, such as polyvinyl alcohol particles, achieve better penetration, but their effects are short lived, often leading to recanalization. The authors sought to overcome these obstacles by developing a technique to enhance glue penetration into the fistula or AVM nidus itself. METHODS: After placing a guide catheter in the proximal feeding artery, a microcatheter is advanced coaxially to its limit. As glue is injected through the microcatheter, a column of 5% dextrose in water (D5W) is pushed manually through the guide catheter lumen to propel the glue forward. This technique has been bench tested in a standard flow model of vascular malformations, using a pump capable of delivering various rates of D5W. It has also been validated in treating 17 patients with cerebral dural arteriovenous fistulae or AVMs, with real-time adjustment of D5W flow according to the extent of glue penetration. RESULTS: In the bench model, the extent of glue penetration, as graded by a new scale of liquid agent embolization proposed by the authors, correlated directly with the rate of D5W flow (P = 0.5, analysis of variance). In vivo, this technique has enhanced the penetration of glue into the fistula or AVM nidus, resulting in longstanding embolization of these malformations. CONCLUSION: Coaxial injection of D5W through the guide catheter can propel cyanoacrylate glue through tortuous feeding arteries and can enhance its penetration into dural fistulae and AVMs, leading to more effective endovascular treatment of these malformations.