Facial nerve palsy after ethylene vinyl alcohol arterial embolization of glomus tympanicum

Background & objective: Glomus tympanicum and jugulare tumors are highly vascular and are therefore commonly embolized before surgical resection to prevent intra-operative bleeding. We report a case of facial nerve paralysis after pre-operative embolization for a glomus tympanicum tumor with ethylene vinyl alcohol (EVOH also known as Onyx) embolic agent. We discuss the choice of embolic agent in relation to the risk of this complication and potential management strategies. Methods: A 57F with right glomus tympanicum developed right facial nerve palsy immediately after embolization. She received 24 mg of dexamethasone over the course of 24 h immediately following her embolization, surgical facial nerve decompression concurrent with tumor resection, and a 10-day prednisone taper. Our main outcome measure was facial nerve function on follow-up physical examinations. Results: The patient developed right facial paralysis (HB 6/6) after Onyx embolization of branches of the external carotid artery system, likely due to translocation of embolic agent into facial nerve vasa nervosa as seen on postembolization CT. No immediate improvement was observed with high dose steroids and decompression, however over the next 6 months her facial nerve function began to improve (HB 3/6). Conclusions: Surgical excision is the standard of care for glomus jugulare and glomus tympanicum tumors. Due to their propensity to bleed, their arterial feeders (branches of the external carotid) are often embolized prior to surgery, however, facial nerve paralysis is a rare but serious complication. There is a possible relationship between the choice of embolic agent and this complication. Though facial palsy is of sufficient rarity that no standard treatment pathway exists, due to the impact on a patient's quality of life, we recommend aggressive therapy to salvage nerve function.