Spinal dural arteriovenous fistulae draining to the anterior spinal vein: Angiographic diagnosis

OBJECTIVE: To describe and present atypical spinal dural arteriovenous fist ulae (SDAVFs) that drain into the anterior spinal vein (ASV) and thus cause some degree of difficulty in differentiating the anterior spinal artery fr om the ASV. METHODS: A retrospective review of 80 selective spinal angiography procedur es (with or without endovascular treatment) performed on SDAVFs since 1980 identified three cases in which the venous drainage was into a dilated ASV via a radicular vein. The patients included two men and one woman, ranging in age from 55 to 82 years (mean age, 71 yr), all of whom presented with mi ld to severe progressive paraparesis and sensory disturbance. RESULTS: The appearance of the venous drainage mimicked that of the usual h airpin configuration of the radiculomedullary artery and therefore caused d iagnostic difficulty. There are no characteristic clinical features that di fferentiate this form of SDAVF from the usual type of SDAVF. The angiograph ic criteria for identification of the ASV draining an SDAVF include the dem onstration of the branching of the ASV and its drainage into the epidural v ein, opacification of other medullary veins connected with the ASV, recogni tion of distortion of the hairpin shape,and the identification of the anter ior spinal artery at the segment where the ASV is opacified. Two patients w ere treated with embolization and one with surgery. All patients improved a fter the treatment. CONCLUSION: Before performing endovascular treatment, thorough spinal angio graphy with an appropriate field of view must be performed to identify this unusual type of SDAVF.