A Case of Cavernous Sinus Dural Arteriovenous Fistula Draining Solely to the Superior Ophthalmic Vein with Normal Cerebral Venous Flow from the Superficial Middle Cerebral Vein to the Inferior Petrosal Sinus due to a Septum in the Cavernous Sinus

OBJECTIVE: We report here an atypical case of cavernous sinus dural arteriovenous fistula (CSDAVF) with a septation that separates the cavernous sinus (CS) into two components, namely, normal cerebral venous drainage and shunted blood drainage into the superior ophthalmic vein (SOV) alone. The CSDAVF was successfully treated by selective transvenous embolization (TVE) through the septum with the trans-inferior petrosal sinus (IPS) approach. CASE PRESENTATION: A 74-year-old woman presented with right exophthalmos and tinnitus on the right side. Neuroradiological examination showed CSDAVF mainly supplied by multiple feeders from the bilateral ascending pharyngeal artery and meningohypophyseal trunk with a shunted pouch located medial-dorsally to the right CS. Blood from the CSDAVF drained via the anterior component of the CS to the right SOV only. Normal cerebral venous blood from the right superficial middle cerebral vein drained through the dorsolateral component of the right CS into the right IPS. These findings suggest that a septal barrier exists between the outflow tract of the dural arteriovenous fistula and the normal cerebral venous outflow tract within the CS. The CSDAVF was successfully treated by selective TVE through the septum with the trans-IPS approach after detailed evaluation of 3D rotational angiography (3DRA) and MRA/MR venography (MRV) cross-sectional images. The patient’s symptoms improved, and she was discharged uneventfully. CONCLUSION: Septation within the CS can completely separate the drainage route of the CSDAVF from the normal cerebral drainage route. Successful catheterization to the shunted pouch through the septum with the IPS approach and selective embolization were possible with detailed evaluation of anatomy on MRA/MRV cross-sectional images and 3DRA images.