Dural non-cavernous sinus arteriovenous fistulas symptomatically simulating spontaneous carotid-cavernous fistulas: an analysis of angiographic findings.

The sites of fistulas and patterns of venous drainage in 34 consecutive cases of dural AVFs manifesting symptoms suggesting CCFs were retrospectively analyzed to determine the frequency of dural AVFs in sites other than the cavernous sinus and to ascertain their causative mechanisms. In five cases (15%), dural AVFs were demonstrated in sites other than the cavernous sinus. Among four, retrograde venous flow due to occlusion of the outflow tract or a rapid-flow shunt resulted in filling of the superior ophthalmic vein. A rapid-flow dural AVF in the anterior cranial fossa showed no occlusive changes in the sinuses, and increased pressure in the cavernous sinus was thought to be responsible for the symptoms. Embolization was effective for relief of the symptoms. Symptoms mimicking CCFs can be seen in dural AVFs in sites other than the cavernous sinus with retrograde venous drainage or with a rapid-flow shunt, conditions which are not as rare as previously believed.