Long-Term Facial Nerve Function in Patients with Vestibular Schwannoma

Background: The initial treatment strategy in small- and medium-sized vestibular schwannoma (VS) remains controversial, and facial nerve function following treatment has long been one of the few standards by which treatment options are compared. The majority of the VS literature examining facial nerve outcomes has been restricted to retrospective reviews of single modality cohorts using physician-evaluated outcome parameters. Publications comparing long-term facial nerve function between microsurgery (MS), radiosurgery (GKS), and observation are few.

Objective: The aim of this study is to characterize long-term objective and self-reported facial nerve symptoms in a large cohort of patients with sporadic small- and medium-sized VS.

Methods: Patients with ≤ 3 cm VS who underwent primary MS, GKS, or conservative management between 1998 and 2008 at two independent tertiary referral centers were identified. Baseline and follow-up clinical data were extracted from existing VS databases and supplemented by clinical chart review. At a mean time of 7.7 years after initial treatment, patients were surveyed via a postal questionnaire using the facial disability index (FDI).

Results: The response rate for patients with VS was 79%. A total of 539 respondents were analyzed. Of 539 patients, 148 patients had been conservatively managed, 247 patients had been treated with GKS, and 144 patients had been treated with MS. Most patients (98.5%) had normal facial nerve function at the time of diagnosis. Overall, 92.4% of the patients had normal facial nerve function as evaluated by House-Brackmann (HB) at the last clinical follow-up. All conservatively managed patients had preserved facial nerve function, five GKS-treated patients (2%), and 28 MS-treated patients (19.4%) had worsened facial nerve function (p < 0.001; surgery against no surgery). MS-treated patients had poorer FDI social/well-being score than patients treated with GKS (p = 0.036), but there was no difference between the remaining groups. MS-treated patients also had poorer FDI physical score than the two other treatment groups, and there was no difference between the GKS group and the conservatively managed patients. Treatment modality was independently associated with both poorer facial nerve functions as evaluated by the physician and according to the FDI results. In patients with HB-grade 1 at the last clinical follow-up, MS-treated patients had a poorer physical FDI score due to “excessive tearing and drying of the eye,” “difficulties eating,” and “difficulties drinking.”

Conclusion: Overall and almost 8 years after initial treatment, 6% of patients treated for VS had poorer facial nerve function. Treatment with MS was the strongest predictor of poorer facial nerve outcomes, but there is clear treatment and selection bias that confound the conclusions of our study.