Preoperative electroneuronography and facial nerve outcome in acoustic neuroma surgery

Objective: To determine whether preoperative electroneuronography (ENoG) predicts facial nerve outcome in patients undergoing acoustic neuroma surgery. Study Design: Prospective, consecutive patients undergoing surgery for acoustic neuroma. Setting: A private tertiary otology and neurotology practice. Patients: One hundred consecutive patients presented for surgical removal of an acoustic neuroma between May 1992 and September 1993. The mean patient age was 49 years (range 17-77). Forty-three percent were male and 57% were female. The mean tumor size was 1.77 cm (range 3 mm to 5 cm). The tumors were removed by a translabyrinthine approach in 59% of patients, via the middle fossa in 40%, and retrosigmoid in 1 %. The facial nerve was anatomically intact at the conclusion of the operation in all but one patient. Intervention: Preoperative ENoG in all patients undergoing surgical removal of their acoustic neuromas. Main Outcome Measures: Facial nerve outcome was measured using the House-Brackmann scale immediately after the operation, 5-7 days after surgery, and >1 year after surgical resection. Results: Preoperative ENoG had no predictive value in determining immediate or eventual facial nerve outcome. Conclusions: ENoG has no value in predicting the facial nerve outcome in acoustic neuroma patients. The results of this study are similar to reports with smaller series in the literature. Preoperative ENoG has proven useful, in another study from this institution, in predicting the possible presence of a facial nerve neuroma. This test may be helpful in determining the possible etiology of an intracanalicular mass.