Onyx Embolization of Carotid-Cavernous Fistulas and Its Impact on Intraocular Pressure and Recurrence: A Case Series

BACKGROUND: Carotid-cavernous fistulas (CCFs) are acquired pathological shunting lesions between the carotid artery and the cavernous sinus leading to elevated intraocular pressure (IOP). CCFs are commonly treated via endovascular embolization, which theoretically restores physiological pressure differentials. OBJECTIVE: To present our institutional data with CCF treated with embolization and discuss endovascular routes, recurrence rates, and dynamic IOP changes. METHODS: Retrospective analysis of 42 CCF patients who underwent Onyx (Covidien, Irvine, California) embolization and pre- and postoperative IOP measurement at a single institution. RESULTS: CCFs were 19.0% direct (type A) and 81.0% indirect (types B, C, or D). Onyx-18 liquid embolisate was used during all embolizations. Overall rate of total occlusion was 83.3% and was statistically similar between direct and indirect fistulas. Preoperative IOP was elevated in 37.5%, 100.0%, 75.0%, and 50% in type A, B, C, and D fistulas, respectively. Average ΔIOP was -7.3 ± 8.5 mmHg (range: -33 to +8). Follow-up time was 4.64 ± 7.62 mo. Full angiographic occlusion was a predictor of symptom resolution at 1 mo (P =. 026) and 6 mo (P =. 021). Partial occlusion was associated with persistent symptoms postoperatively at 1 mo (P =. 038) and 6 mo follow-up (P =. 012). Beyond 6 mo, negative ΔIOP was associated with continued symptom improvement. Recurrence occurred in 9.5% of patients, all of which were indirect CCFs. CONCLUSION: Onyx embolization of CCF is an effective treatment for CCF and often results in the reversal of IOP elevation. Full occlusion predicts favorable clinical outcomes up to 6 mo. Postoperative IOP reduction may indicate favorable long-term clinical outcomes.