A case of posterior ischemic optic neuropathy in a posterior-draining dural cavernous sinus fistula.

A 79-year-old woman presented with sudden unilateral visual loss after an ocular motor disturbance and pulsatile tinnitus. Neuro-ophthalmologic examination showed a presumed right posterior ischemic optic neuropathy (PION), oculosympathetic, and third, sensory fifth, and sixth cranial nerve pareses. Selective angiography of the right internal and external carotid arteries confirmed a posterior-draining dural carotid cavernous sinus fistula (CCF) fed by the right meningohypophyseal trunk and right middle meningeal artery. Angiography also showed an ophthalmic-middle meningeal arterial anastomosis. We postulate that the PION was caused by an arterial steal, because blood was drawn into the fistula and away from the intraorbital optic nerve.