Type I Spinal Arteriovenous Fistula with Ventral Intradural Venous Drainage: A Proposal of a Modified Classification

OBJECTIVES: Spinal arteriovenous fistula (AVF) is the most common spinal vascular lesion and constitutes an abnormal communication between a feeder artery and a draining vein. Arterialization of the venous plexus leads to venous hypertension; consequent edema and congestion of the spinal cord are associated with progressive neurological decline. PATIENTS AND METHODS: In this report, we describe two unique cases of type I cervical spinal AVF, in which a radiculomeningeal artery forms an intradural fistula that drains into the ventral venous plexus. RESULTS: Both patients underwent surgical obliteration of the fistula with complete occlusion confirmed on postoperative angiography. CONCLUSION: Both cases do not fit into the current classification scheme. A modified classification is proposed.