Patient-reported outcomes are increasingly used in studies of vestibular schwannoma (VS); however, few studies have examined self-evaluated facial nerve function and its relation to physician-reported outcomes. The primary objective of this study was to compare patient self-evaluations of facial disability with physician-evaluated facial nerve status and with self-evaluations of a healthy control group. The second objective was to provide insight into the controversial subject of the optimal initial management of small- and medium-sized VSs; consequently, the authors compared patient-reported facial nerve disability following treatment via observation (OBS), Gamma Knife surgery (GKS), or microsurgery (MS). Lastly, the authors sought to identify risk factors for facial nerve dysfunction following treatment for small- and medium-sized VSs.
All patients with a VS 3 cm or smaller that was singly treated with OBS, GKS, or MS at either of 2 independent treatment centers between 1998 and 2008 were retrospectively identified. Longitudinal facial nerve measures and clinical data, including facial nerve evaluation according to the House-Brackmann (HB) grading system, were extracted from existing VS databases. Supplementing the objective data were Facial Disability Index (FDI) scores, which were obtained via survey of patients a mean of 7.7 years after initial treatment.
The response rate among the 682 eligible patients was 79%; thus, data from a total of 539 patients were analyzed. One hundred forty-eight patients had been managed by OBS, 247 with GKS, and 144 with MS. Patients who underwent microsurgery had larger tumors and were younger than those who underwent OBS or GKS. Overall, facial nerve outcomes were satisfactory following treatment, with more than 90% of patients having HB Grade I function at the last clinical follow-up. Treatment was the major risk factor for facial nerve dysfunction. Almost one-fifth of the patients treated with MS had an objective decline in facial nerve function, whereas only 2% in the GKS group and 0% in the OBS cohort had a decline. The physical subscale of the FDI in the VS patients was highly associated with HB grade; however, the social/well-being subscale of the FDI was not. Thus, any social disability caused by facial palsy was not detectable by use of this questionnaire.
The majority of patients with small- and medium-sized VSs attain excellent long-term facial nerve function and low facial nerve disability regardless of treatment modality. Tumor size and microsurgical treatment are risk factors for facial nerve dysfunction and self-reported disability. The FDI questionnaire is sensitive to the physical but not the social impairment associated with facial dysfunction.