Risk-benefit analysis of using the middle fossa approach for acoustic neuromas with >10 mm cerebellopontine angle component

Objectives: To evaluate hearing preservation and facial nerve (FN) outcome in the middle fossa (MF) approach for acoustic neuromas with a cerebellopontine angle (CPA) component >10 mm. Study Design: Retrospective review of 193 patients. Patient Population: Patients were grouped according to tumor size: intracanalicular tumors (IC; 64), 1 to 9 mm CPA extension (42), and 10 to 18 mm CPA extension (47). Additionally, a group of 40 patients (tumor size 10-18 mm CPA extension) who had undergone a translabyrinthine (TL) approach was studied to assess comparative FN outcome. Hearing and FN function were measured 1 year postoperatively. We defined the success at functional hearing preservation as AAO-HNS class B or better and good FN outcome as House-Brackmann grade II or better. Results: For IC tumors and those with up to 9-mm CPA extension, there was no significant difference in the rate of functional hearing preservation (62.2% vs. 63.1%, P = .931) and good FN outcome (93.7% vs. 97.6%, P = .358). For tumors of 10- to 18-mm CPA extension, the rate of hearing preservation (34%) was lower than the other groups (P = .006 and P = .009). In this group, the rate of good FN outcome was lower compared with the IC and 1- to 9-mm tumors (80.8% vs. 93.7%, P = .037 and 97.6%, P = .012). The rate of good FN outcome following the TL approach in a comparable cohort of patients was 100% (P = .003 in comparison with 10-18 mm tumor resected with the MF approach). Conclusions: When considering surgical options, patients with > 10-mm tumors should be advised that choosing the MF approach for hearing preservation carries a somewhat higher risk of persistent FN dysfunction.