Imaging description

Spinal dural arteriovenous fistula (DAVF) is the most common spinal vascular malformation. It is an intradural-extramedullary lesion commonly found in the distal cord or at the conus medullaris and is composed largely of distended intradural draining veins. MRI typically shows a distal spinal cord which is enlarged and edematous due to venous congestion, with corresponding hypointensity on T1- and hyperintensity on T2-weighted images. In the setting of venous hypertensive myelopathy, the cord edema can spare the periphery and the central edema can be “flame shaped” at its superior and inferior margins; these findings typically are best appreciated on T2 series (Figure 29.1). Close inspection will often show multiple abnormal vessel flow voids on the pial surface of the cord.

When a spinal DAVF is suspected on MRI, thoracic spine MRI or MR angiography (MRA) can be considered as the next diagnostic modality for evaluation of the extent of spinal involvement [1]. However, catheter angiography should be considered in all cases as this will confirm the diagnosis and help identify the exact level of the vascular shunt to plan for endovascular embolic therapy [2].