Arteriovenous fistulas of the cervicomedullary junction as a cause of myelopathy: radiographic findings in two cases.

Spinal dural arteriovenous fistulas (SDAVFs) represent an abnormal connection between a dural artery and an intradural radicular vein. The radicular vein drains the medullary venous plexus , which dilates in response to arterial pressure, resulting in enlarged serpiginous vessels , usually posterior to the spinal cord. This finding is not specific for SDAVF, as it can be found in most spinal arteriovascular malformations (AVMs) as well as hemangioblastomas. SDAVFs can be differentiated from intramedullary arteriovenous malformations in that the arteriovenous connection in SDAVF is extramedullary, lying outside the cord substance within the dura. Clinically, SDAVFs usually present as a slowly progressive myelopathy or radiculopathy in middle-aged to elderly patients, that can mimic other spinal pathology [1]. Since most SDAVFs are located in the lower thoracic and lumbar regions, with symptoms referable to the conus, angiegraphic searches may be limited to the thoracic, lumbar, and sacral contribution to the dural arterial supply [1]. However, the site of the SDAVF may be far removed from the portion of the spinal cord affected cl inically. As illustrated in the two cases that follow, conus-related symptoms can result from an arteriovenous fistula located as high as the cervical canal. In these two cases , as well as six others from the literature, exhaustive angiographic evaluation of all possible vascular pedicles was required to identify and treat the SDAVF.