Figure 4. Perimedullary arteriovenous malformation. An enlarged dorsal perimedullary venous complex with an associated venous aneurysm (arrow) on the dorsal surface of the cord is demonstrated on sagittal (a) and reconstructed coronal (b) CISS images. (c) Vertebral artery angiogram showing supply from the anterior spinal artery axis and the corresponding angiographic features. The aneurysm is faintly filled in on this early arterial phase image.