Lateral cerebral angiogram with right common carotid artery injection. Note cavernous sinus fistula (ill-defined area, white arrows) filling from both the external (red arrowheads) and internal (white arrowheads) branches. The superior ophthalmic vein (red arrow) is markedly enlarged and fills inappropriately during the early arterial phase of this study, consistent with a carotid cavernous sinus fistula.