Case of white-eyed shunt carotid-cavernous sinus fistula mimicking optic neuritis

Abstract

Background: The typical orbito-ocular manifestations of carotid-cavernous sinus fistulas are conjunctival hyperemia, chemosis and exophthalmos as a result of increased fistular flow directed anteriorly in the ophthalmic veins. These congestive features are absent if the flow is directed posteriorly, resulting in “white-eyed shunts.” We describe a rare carotid-cavernous sinus fistula case presenting with optic neuritis-like manifestations. Case presentation: A 71-year-old Japanese woman developed periorbital pain, impaired visual acuity with an upper horizontal visual field defect, diminished light reflexes and a relative afferent pupillary defect in her right eye. There were no congestive features in her eyes. Intraocular pressure was normal in both eyes, but fundoscopy revealed a pale optic disc in the right eye. Serum anti-aquaporin-4 antibodies were negative. Although optic neuritis was suspected, high-dose corticosteroid administration did not result in improvement. When referred to Department of Neurology, Gunma University Hospital, she showed a subtle, incomplete oculomotor nerve palsy in the right eye. Magnetic resonance angiography suggested carotid-cavernous sinus fistula (CCF), and cerebral angiography showed fistulous drainage into the cavernous sinus and inferior petrosal sinus, and a delayed opacification of the superior orbital and angular facial veins on the right side. A diagnosis of white-eyed shunt CCF was made, and a coil embolization procedure was carried out. However, there was no symptom improvement. Conclusions: It is difficult to diagnose white-eyed shunt CCF based only on physical findings, especially when there is an absence of ocular congestive features. We discuss the possible mechanisms underlying the optic neuritis-like symptoms of CCF.