Transverse-sigmoid Sinus Dural Arteriovenous Fistula Presenting with False Localizing Signs of Cavernous Sinus Dural Arteriovenous Fistula Due to Obstructed Cerebral Venous Outflow into the Bilateral Superior Ophthalmic Veins: A Case Report

Cavernous sinus (CS) dural arteriovenous fistula (dAVF) presents ocular symptoms and visual disorders due to retrograde drainage from the CS into the superior ophthalmic vein (SOV). Some papers reported non-CS dAVFs with those symptoms. We present a unique case of transverse-sigmoid sinus (TSS) dAVF with localizing signs of CS dAVFs resulting from congested cerebral venous outflow into the CSs and SOVs in an 86-year-old female patient. Right pulsatile tinnitus and chemosis appeared a few years ago. After experiencing progressive bilateral blurred vision and decreased visual acuity with papillary edema for a few months, she was admitted to our hospital. Cerebral angiography demonstrated right sigmoid sinus dAVF with retrograde venous reflux into the superior sagittal sinus (SSS) and contralateral TSS without cortical venous reflux. Under the influence of congestion of the SSS, cerebral venous outflow drained into the CSs subsequently into the SOVs. Trans-arterial embolization using ethylene-vinyl alcohol copolymer was conducted via the right middle meningeal artery. After treatment, right chemosis immediately improved. The 2-month follow-up examination revealed resolution of bilateral visual acuity and improvement of papillary edema. Our case demonstrates that retrograde drainage into the SOVs with not only directly arterialized shunted flow but also congested cerebral venous outflow can cause CS dAVFs-like symptoms.