Successful management of spinal dural arteriovenous fistulas undetected by arteriography. Report of three cases.

Spinal dural arteriovenous fistulas (AVFs) frequently cause progressive myelopathy. When they are localized by imaging studies, surgery can be safely performed by simply interrupting the vein draining the fistula intradurally, and the results will be excellent and lasting. In some patients with clinical features of a spinal dural AVF and in whom magnetic resonance imaging and/or myelography findings are consistent with a diagnosis of a spinal dural AVF, however, spinal arteriography demonstrates no such results. The authors used a simple strategy based on knowledge of the epidemiology, pathophysiology, and anatomy of spinal dural AVFs to manage these cases successfully. In two patients, atherosclerotic occlusion was the primary cause for the failure of arteriography to visualize the dural AVF. The presence of an aortic aneurysm was an additional contributing factor preventing arteriographic visualization in one of these patients. In a third patient, massive obesity, and aortic atheroslerosis and tortuosity contributed to the absence of findings on three spinal arteriograms before surgical exploration lead to a more focused arteriographic examination that was successful.