Abstract Number ‐ 80: Embolization of Carotid Cavernous Fistula Through Occluded Inferior Petrosal Sinus Access
Authors: Krothapalli Neeharika , Fayad Mohamad , Miller Ethan , Sussman Eric , Bruno Charles , Ollenschleger Martin , Mehta Tapan 
Published: April 2023

Introduction
Carotid cavernous fistula (CCF) is an abnormal communication between arteries and veins within the cavernous sinus. The most common presenting symptoms are proptosis, chemosis, orbital bruit and headache. Visual disturbances such as diplopia, ophthalmoplegia and cranial nerve deficits can also occur. Pulsatile tinnitus is an unusual finding which necessitates further workup in this population. Endovascular obliteration with transvenous embolization for indirect fistulas is the preferred approach for CCF closure. Navigation is achieved through the inferior petrosal sinus or facial and superior ophthalmic vein. Here, we describe a case of carotid cavernous fistula that was successfully treated through occluded right inferior petrosal sinus access using coil and Onyx embolic material.

Methods
A 56‐year‐old‐male with no past medical history presented with right eye proptosis and pulsatile tinnitus. His eye symptoms progressively worsened with decrease in visual acuity, gaze restriction and exophthalmos which correlated with the resolution of pulsatile tinnitus. MRI demonstrated significant inflammation involving the right orbit and atypical enhancement of basal frontal lobe adjacent to orbit. MRA suggested early opacification of the right superior ophthalmic vein and subtle flow voids in posterior lateral aspect of right cavernous sinus. Further evaluation with cerebral angiogram revealed a Barrow Type D right carotid cavernous fistula supplied by meningo‐hypophyseal branches of bilateral internal carotid arteries and right internal maxillary branch. It demonstrated high flow retrograde shunting in right superior ophthalmic vein and a basal frontal isolated cortical vein. There was near complete occlusion of the right sigmoid sinus and inferior petrosal sinus due to significant thrombus burden as well as stenosis of the right internal jugular vein.

Results
Patient underwent embolization of right carotid cavernous fistula with transvenous approach. A microcatheter was advanced to the origin of the intercavernous sinus but was not able to cross due to exceptionally small channels connecting both cavernous sinuses. The right internal jugular vein was subsequently identified and injection demonstrated occlusion of right sigmoid sinus due to near complete occlusive thrombus in addition to occlusion of the major channels of the inferior petrosal sinus. The microcatheter was blindly advanced into the inferior petrosal sinus maintaining the symmetry from contralateral inferior petrosal sinus trajectory. We were able to reach the fistulous point in the posterior medial aspect of the right cavernous sinus using an Echelon 1045 microcatheter. Coils were subsequently deployed and fistula was noted to be occluded. Onyx was injected through the microcatheter to avoid recanalization of fistula. A follow‐up left internal carotid artery and right common carotid artery injections confirmed angiographic cure of the fistula.

Conclusions
Carotid cavernous fistula is a rare but treatable cause of rapidly progressive vision loss with pulsatile tinnitus as an unusual finding. We present a case of challenging access and successful treatment with transvenous approach through near complete occlusion of the inferior petrosal sinus.