Cognard Type V Dural Arteriovenous Fistula Involving the Occipital Sinus

The Cognard type V dural arteriovenous fistula (dAVF), which has a drainage route into the spinal vein, is a rare subtype of cranial dAVF. Because of typical features such as progressive myelopathy and brainstem dysfunctions, aggressive treatments should be considered. To eliminate venous congestion of the spinal cord, various approaches including surgical interruption of the spinal draining vein or transarterial embolization with cyanoacrylate have been reported. The introduction of nonadhesive Onyx has changed the treatment of dAVF, although little is known about the clinical usefulness of this type of fistula. We describe a case of the Cognard type V dAVF, draining into the spinal vein through the occipital sinus (OS) successfully treated by transarterial double catheter injection of Onyx. We used the alternating injections from 2 microcatheters until the Onyx reached the OS and reflowed into feeders adequately. This technique contributed to the elimination of the remaining afferent flow in an early stage of Onyx injection and achieved enough penetration into the draining vein.