Angiographically occult spinal dural arteriovenous fistula located using selective computed tomography angiography. Case report.

Spinal dural arteriovenous fistula (DAVF) is the most common type of spinal arteriovenous malformation and may cause progressive myelopathy but is usually treatable in the early stages by direct surgery or intravascular embolization. Selective spinal angiography has been the gold standard for diagnosis, but angiographically occult DAVF is not uncommon. A 67-year-old man presented with a 2-year history of progressive paraparesis. Magnetic resonance (MR) imaging demonstrated segmental atrophy of the spinal cord and dilated coronary veins on the dorsal surface of the spinal cord. A DAVF was suspected, but repeated selective angiography failed to demonstrate the fistula. Findings from spoiled gradient echo MR imaging suggested that the draining vein flowed into the dilated venous plexus at the T-9 level. Selective computed tomography (CT) angiography of the right T-9 intercostal artery confirmed the location of the fistula. The authors successfully occluded the draining vein through surgery, and they observed that the fistula was low flow. The patient exhibited improvement in his symptoms, and postoperative MR imaging confirmed closure of the fistula. Selective CT angiography is useful in locating the draining vein of angiographically occult DAVF and therefore minimizing the extent of the surgical procedure.