Bilateral Posterior Ischemic Optic Neuropathy Due to Bilateral Anterior-Drainage Dural Carotid-Cavernous Fistulas: A Case Report

Abstract

To report a case of bilateral posterior ischemic optic neuropathy (PION) due to bilateral anterior-drainage dural carotid-cavernous fistulas (CCFs). We report on a 62-year-old woman with a history of poorly controlled hypertension who presented with sudden bilateral visual loss and headache for 5 days. She denied a history of head trauma. On examination, her visual acuities were no light perception (NLP) with fixed pupils in both eyes. The ocular motility of both eyes was limited in all directions. Both eyelids were difficult to open. Anterior segment examination revealed bilateral chemosis and episcleral corkscrew vessels. Intraocular pressures were 45 and 48 mmHg in her right and left eyes, respectively. Gonioscopy revealed blood in Schlemm's canal at the nasal angle of the right eye. Fundus examination showed slightly dilated and tortuous retinal veins with normal-appearing optic discs in both eyes. The cup-to-disc ratios were 0.3 bilaterally. Other neurological examinations were unremarkable. Magnetic resonance imaging demonstrated dilation of the bilateral superior ophthalmic veins (SOVs), and marked orbital and periorbital congestion bilaterally. However, there was no compression or stretching of the bilateral optic nerves. Diffusion restriction on diffusion-weighted imaging, with corresponding reduced apparent diffusion coefficient, in the entire bilateral orbital segment of the optic nerves was revealed, consistent with bilateral PION. Magnetic resonance angiography revealed arterialization of the bilateral cavernous sinuses and SOVs. Cerebral angiography confirmed the diagnosis of bilateral anterior-drainage dural CCFs. Treatment with transvenous coil embolization was successful. Three months after embolization, ophthalmic examination demonstrated progressive improvement of aforementioned ophthalmic signs; however, her visual acuities remained NLP in both eyes. To our knowledge, this is the first reported case of bilateral PION due to bilateral anterior-drainage dural CCFs. In spite of its rarity, PION should be considered as a severe, irreversible ophthalmic complication of anterior-drainage dural CCF.