Objective: To determine nerve of origin, tumor size, hearing preservation rates, and facial nerve outcomes in a retrospective cohort study of patients undergoing translabyrinthine (TL), middle cranial fossa (MCF), and retrosigmoid/suboccipital (SO) approaches to vestibular schwannomas (VS).
Study design: Retrospective.
Methods: Chart review.
Results: Patient charts from 231 TL, 70 MCF, 53 SO, and 5 combined TL/SO procedures for VS were evaluated in 356 patients. The inferior vestibular nerve (IVN) was the nerve of origin in 84 of 359 cases (23.3%), while the superior vestibular nerve (SVN) was the nerve of origin in 36 patients (10%). In 239 of 359 cases (66.6%), the nerve of origin was not identified. Forty patients undergoing hearing preservation surgery had hearing results and nerve of origin data available for review. Functional hearing (<50dB PTA and >50% speech discrimination) was preserved in 10 of 15 patients (75%) with SVN tumors, while only 7 of 25 patients (28%) with IVN tumors retained functional hearing. Facial nerve outcomes and nerve of origin were recorded simultaneously in 109 patients. Seventy-one of 74 patients (95%) patients with IVN tumors achieved a House-Brackmann (HB) grade I-III, while 35 of 35 patients (100%) with SVN tumors retained HB I-III facial function. Looking at tumor size versus hearing preservation, functional hearing was preserved in 22 of 49 patients (45%) with <1-cm tumors, and 4 of 20 patients (20%) with 1- to 1.5-cm tumors. For all cases with documented facial nerve function, HB I-III were achieved in 96% of SO, 94% of MCF, and 88% of TL procedures.
Conclusions: Our retrospective data indicated that IVN tumors were twice as common as SVN tumors. The nerve of origin did not affect facial nerve outcomes but did impact hearing preservation rates. Patients with tumors <1 cm in size had the best chance for hearing preservation. Overall facial nerve preservation was excellent with >90% achieving HB 1 to 3 function at final follow-up.