Spinal Arteriovenous Fistulas

Several classifications have been proposed for spinal AVMs.[2],[4]-[6] They can be divided into intramedullary AVMs and arteriovenous fistulas (AVFs). Based on anatomical characteristics, spinal AVFs are classified as extradural AVFs and intradural lesions, including spinal dural AVFs (SDAVFs) and perimedullary spinal AVFs (PMAVFs).[7],[8] Rangel-Castilla et al. classified extradural AVFs as type A or type B based on the availability of intradural venous drainage. In Type A spinal extradural AVFs, there is intradural venous drainage and arterio‐ venous shunting develops in the epidural space. Type B can be further classified as B1 and B2, both of which are limited to the epidural space without any intradural draining veins. The only difference between these two types is the presence or absence of compression on the spinal cord and nerve roots.[9] There is a paucity of literature about spinal AVFs and due to the very small incidence of these lesion, almost all available studies are small cases series. However, spinal AVFs can manifest with severe neurologic symptoms, leading to permanent neurologic deficit. Therefore, in this chapter we aim to review the available literature about spinal AVFs.