Spinal Osseous Epidural Arteriovenous Fistula with Multiple Small Arterial Feeders Converging to a Round Fistular Nidus as a Target of Venous Approach

A 21-year-old female patient presented with both lower leg weakness and voiding difficulty. Sagittal T2-weighted MR image (A) shows the high signal intensity of the diffusely swollen spinal cord. Note the tortuous vessels around the cord surface. Arterial phase of the L2 lumbar artery (B) shows multiple fine feeders of fistula draining into the dilated epidural venous sac. Venous phase (C) of the upper level shows medullary venous engorgement and venous drainage through the hemiazygos vein into the opening site of the azygos vein to the superior vena cava (arrow). Final angiogram (D) after GDC embolization shows complete obliteration of the fistula. Sagittal T2-weighted image (not shown) obtained 6 months later shows the normalized contour and signal intensity of the spinal cord. Contrast-enhanced axial T1-weighted image (E) reveals low signal intensity of the packed coils within the bony defect of the L2 body and pedicle maintaining dural integrity at the site of the dilated venous sac. The patient’s neurologic deficit had disappeared completely.