Preservation of facial nerve function after resection of vestibular schwannoma

Objective. Most data regarding facial nerve function in patients undergoing microsurgical resection of vestibular schwannomas predominantly include series performed at a single institution. In an effort to minimise individual surgeon or institutional bias, we performed an analysis of the published literature on facial nerve outcomes following microsurgical resection of vestibular schwannomas. The objective of this study was to provide a comprehensive assessment of reported outcomes for facial nerve preservation after VS surgery. Materials and methods. We identified a total of 296 studies involving over 25,000 patients that included outcome data for facial nerve function of vestibular schwannoma patients treated surgically. Data regarding surgical approach, tumour size, patient age, and use of intra-operative monitoring were extracted and correlated with facial nerve function after surgery. Patients with preoperative facial nerve dysfunction (House-Brackmann score 3 or higher) were excluded and 'facial nerve preservation' was defined as grade I or II House-Brackmann function at last follow-up visit. Results. A total of 79 articles reporting on 11,873 patients met our inclusion criteria contributing to our analysis. Patients treated with the middle cranial fossa approach had a trend towards higher overall facial nerve preservation rate (85%), compared to the translabyrinthine approach (81%, p=0.07), and did statistically better than the retrosigmoid approach (78%, p<0.0001). Patients with an average tumour size <20 mm had significantly improved facial nerve preservation rates, compared to larger tumours (90% vs. 67%, p<0.0001). Patients under 65 years of age had a lower facial nerve preservation rate (71% vs. 84%, p<0.001). Finally, the use of intra-operative monitoring improved the facial nerve preservation rate (76% vs. 71%, p<0.001). Conclusion. Factors that appear to be associated with facial nerve preservation after microsurgical resection of a vestibular schwannoma include tumour size <20 mm, use of the middle fossa approach and use of neuromonitoring during surgery. These data provide a summary assessment of the published literature regarding facial nerve preservation after microsurgical resection of vestibular schwannoma.