Onyx embolization of a carotid cavernous fistula via direct transorbital puncture

The treatment of indirect carotid cavernous fistulas (CCFs) is challenging and primarily accomplished by endovascular means utilizing a variety of embolic agents. Transvenous access to the cavernous sinus is the preferred method of embolizaiton of indirect CCFs as they are frequently associated with numerous small-caliber meningeal branches. Although the inferior petrosal sinus is the simplest, shortest, and most commonly used venous route to the cavernous sinus, the superior ophthalmic vein, superior petrosal sinus, basilar plexus, and pterygoid plexus present other endovenous options. Occasionally, however, use of these venous routes may not be possible due to vessel tortuosity or sinus thrombosis and occlusion. The authors report a case of an indirect CCF that could not be treated endovascularly due to inability to access the cavernous sinus via a transfemoral transvenous approach. Angiography revealed a small, deeply located superior ophthalmic vein that was thought to be suboptimal for a direct cutdown. The cavernous sinus was cannulated directly via a transorbital approach using fluoroscopic guidance with a 3D skull reconstruction overlay. The fistula was subsequently obliterated using ethylene vinyl alcohol copolymer (Onyx). The technique and advantages of both 3D osseous reconstruction as well as Onyx embolization are discussed.