Surgery versus Radiosurgery for Facial Nerve Schwannoma: Systematic Review and Meta-analysis of Facial Nerve Function

Introduction: Facial nerve schwannomas (FNS) are uncommon, slow-growing tumors that may cause facial weakness. Although management algorithms continue to evolve, long-term facial function remains a key treatment priority. Historically, patients underwent surgical resection with nerve graft following confirmation of FNS; by contrast, contemporary management typically proceeds from a period of conservative management, until facial nerve weakness or other symptoms referable to tumor compression prompts consideration for treatment. The aim of this study was to compare facial nerve function after resection or stereotactic radiosurgery (SRS) for FNS.

Methods: A search of seven electronic databases from inception to July 2019 was conducted following PRISMA guidelines. Systematically-identified articles were screened against prespecified criteria. Facial nerve function outcomes were classified as improved, stabilized, or worsened, from last preintervention exam until last follow-up. Incidence was then pooled by random-effects meta-analyses of proportions.

Results: Forty-three articles with a pooled cohort of 576 FNS satisfied criteria. Thirty-three and 10 articles described outcomes following surgery in 464 (81%) and SRS in 112 (19%) patients, respectively. In the surgery cohort, facial nerve function improved in 20% (95% CI, 12–29%), stabilized in 41% (95% CI, 34–49%), and worsened in 34% (95% CI, 25–43%). In the SRS cohort, facial nerve function was improved in 20% (95% CI, 9–34%), stable in 66% (95% CI, 54–78%), and worse in 9% (95% CI, 3–16%). As compared with SRS, surgery was significantly associated with a lower incidence of stable facial nerve function, and a higher incidence of worsened facial nerve function (p < 0.01). These significant differences were preserved after adjusting for preoperative House-Brackmann grade (≤2 vs. >2).

Conclusion: Although the incidences of improved facial nerve function after FNS treatment are comparable following surgery or SRS, surgery is significantly associated with lower rates of stable facial nerve function, and higher rates of worsened facial nerve function. Further study is required to address potentially confounding sources of clinical heterogeneity.