An Unusual Case of an Ethmoidal Arteriovenous Fistula Draining Into the Superior Ophthalmic Vein: Technical Case Report

BACKGROUND AND IMPORTANCE: Ethmoidal arteriovenous fistulae (AVF) are uncommon and are characterized by an aggressive clinical course. Typical venous drainage is into the frontal cortical veins. We present the case of a 76-year-old male patient who was found to have a right ethmoidal AVF draining directly into the superior ophthalmic vein (SOV), with no cavernous sinus involvement and an associated SOV aneurysm and was successfully treated using surgical cutdown of the SOV followed by endovascular embolization. CLINICAL PRESENTATION: A 76-year-old man presented with chemosis, proptosis, and lid lag with occasional diplopia. Based on the clinical presentation, there was a suspicion of a carotid cavernous fistula. Cerebral angiography demonstrated a right ethmoidal to SOV fistula, without any involvement of the cavernous sinus, and a SOV aneurysm. Transarterial embolization of the fistula was attempted but was unsuccessful. An SOV approach was performed using SOV cutdown followed by endovascular embolization of the fistula from a transocular route using coils and Onyx embolic agent. Therewas complete obliteration of the fistula and associated venous aneurysm. The patient had a remarkable recovery. CONCLUSION: In rare cases, ethmoidal AVFs can present with an unusual venous drainage. Clinical presentation may be similar to carotid cavernous fistulae, and proper identification of the lesion using an angiogram is essential to guide treatment. In cases in which other approaches fail to treat the fistula, direct surgical exposure of the SOV followed by embolization using coiling and Onyx may be successful in achieving AVF occlusion.