Evaluating the Incidence and Neuro-Ophthalmic Manifestations of Carotid-Cavernous Fistulas

Background: To determine the incidence of carotid-cavernous fistula (CCF) and describe the neuro-ophthalmic manifestations and eventual clinical outcomes. Methods: This was a population-based, retrospective cohort study using the Rochester Epidemiology Project to identify patients aged 18 years or older residing in Olmsted County, MN, diagnosed with CCF from 1997 to 2019. The medical records were reviewed for ophthalmic signs and symptoms, including conjunctival chemosis, proptosis, orbital bruit, diplopia, ophthalmoplegia, orbital pain, ocular hypertension, and blurred vision. Also determined was the number of patients with CCF found incidentally on neuroimaging, without clinical manifestations. Results: Ten patients were diagnosed with a CCF between 1997 and 2019 with an overall incidence rate of 0.37 per 100,000 per year (95% CI 0.20–0.68). The median age was 50.5 years (range 23–74 years), 6 (60%) were female, and 9 were White and 1 patient was Korean. Three patients (30%) were asymptomatic and found incidentally on imaging that was obtained for unrelated reasons, and one patient's ocular details were unavailable because she passed away from severe head trauma. The following neuro-ophthalmologic or ocular manifestations were identified in the remaining 6 patients: chemosis/conjunctival injection (n = 6), cranial nerve (CN) VI palsy (n = 6), CN III palsy (n = 2), proptosis (n = 4), ocular/orbital pain (n = 3), audible orbital bruit (n = 2), ocular hypertension (n = 1), and blurred vision (n = 1). Of those patients with symptomatic CCFs, all underwent treatment except for one that spontaneously resolved. None of the patients suffered a stroke or cerebral hemorrhage. The 3 patients with incidentally discovered CCFs were asymptomatic and did not require treatment. Conclusions: This is the first population-based study to show a low incidence rate of CCFs, supporting the notion that it is an uncommon condition. Neuro-ophthalmic manifestations are common, especially chemosis/conjunctival injection and CN VI palsy. Up to a third of patients with CCF can be asymptomatic and may be found incidentally on neuroimaging during the evaluation for unrelated symptoms.