Objective: Intracranial facial nerve schwannomas (FNS) requiring treatment are frequently recommended for surgery or stereotactic radiosurgery (SRS). The objective of this study was to compare facial nerve function outcomes between these two interventions for FNS via a systematic review and meta-analysis.
Methods: A search of the Ovid EMBASE, PubMed, SCOPUS, and Cochrane databases from inception to July 2019 was conducted following PRISMA guidelines. Articles were screened against prespecified criteria. Facial nerve outcomes were classified as improved, stabilized, or worsened by last follow-up. Incidence was pooled by random-effects meta-analysis of proportions.
Results: Thirty-three articles with a pooled cohort of 519 patients with FNS satisfied all criteria. Twenty-five articles described operative outcomes in 407 (78%) patients; 10 articles reported SRS outcomes in 112 (22%). In the surgical cohort, facial nerve function improved in 23% (95% CI 15%-32%), stabilized in 41% (95% CI 32%-50%), and worsened in 30% (95% CI 21%-40%). In the SRS cohort, facial nerve function was improved in 20% (95% CI 9%-34%), stable in 66% (95% CI 54%-78%), and worsened in 9% (95% CI 3%-16%). Compared with SRS, microsurgery was associated with a significantly lower incidence of stable facial nerve function (p < 0.01) and a significantly higher incidence of worsened facial nerve function (p < 0.01). Tumor progression and complication rates were comparable. Outcome certainty assessments were very low to moderate for all parameters.
Conclusions: Unfavorable facial nerve function outcomes are associated with surgical treatment of intracranial FNS, whereas stable facial nerve function outcomes are associated with SRS. Therefore, SRS should be recommended to patients with FNS who require treatment, and surgery should be reserved for patients with another indication, such as decompression of the brainstem. Further study is required to definitively optimize and validate management strategies for these rare skull base tumors.
Keywords: CN = cranial nerve; ES = effect size; FNS = facial nerve schwannomas; GRADE = Grading of Recommendations, Assessment, Development and Evaluations; Gamma Knife; HB = House-Brackmann; PICOS = Population, Intervention, Comparator, Outcome, Study type; SRS = stereotactic radiosurgery; VS = vestibular schwannoma; facial nerve schwannoma; resection; seventh cranial nerve; skull base; stereotactic radiosurgery; stripping; surgery.