Background Onyx is a non-adhesive liquid embolic agent that has gained wide acceptance in the treatment of intracranial pial AVMs. However, only a few series have addressed the results of Onyx embolization for the treatment of dural arteriovenous fistulas (DAVFs). We now report on the long term results of Onyx treatment for intracranial DAVFs.

Methods We performed a retrospective analysis of 37 consecutive patients with intracranial DAVFs (a total of 39 lesions) who were treated with Onyx as the single treatment modality between March 2006 and April 2009. A trans-arterial approach was employed in all cases, and Onyx-18 or a combination of Onyx-18/Onyx-34 was used to embolize the DAVF. Patients underwent control angiography at 3 months and 12 months post-embolization to assess for recurrent or residual shunting.

Results Mean age of these 37 patients was 56±11 years (median 56, range 30–76). There were 22 men and 15 women. 11 lesions (29.7%) were classified as Cognard IV/Borden 3; 14 lesions (37.8%) as Cognard III/Borden 3; four lesions (10.8%) as Cognard IIa + IIb/Borden 2; three lesions (8.1%) as Cognard IIb/Borden 2; one lesion (2.7%) as Cognard IIa/Borden 1; and four lesions (10.8%) as Cognard I/Borden 1. A total of 46 procedures were performed (three procedures in three patients; two in three patients; and one in 31 patients). Complete angiographic cure on immediate post-treatment angiography was achieved in 35 patients. One patient underwent surgical resection after partial embolization. The remaining patient had a residual fistula involving the jugular fossa below the skull base without evidence of any residual intracranial component. Complications included one asymptomatic extracranial vertebral artery dissection and two facial palsies. There was no other significant morbidity or mortality. Follow-up angiography is currently available in 34 patients. There was no evidence of residual or recurrent DAVF in 33 patients. One of the initially “cured” patients had evidence of a small recurrent DAVF on short-term follow-up. This was attributed to lack of penetration of the embolic agent into the proximal venous compartment. This patient was asymptomatic and was subsequently embolized with Onyx resulting in stable cure on follow-up angiogram performed 11 months later. Twenty-one patients have long term (>1 year) follow-up; 19 of these had follow-up angiography at both 3 and 12 months. In all these 19 cases, the angiographic results were stable across the two time epochs.

Conclusion In our experience, the endovascular treatment of intracranial DAVFs with Onyx is safe and highly effective with no evidence of any significant recurrence in the long term follow-up. A single angiography at 3–6 months appears to be reasonable in the follow-up of these patients.