Clinical Implication of Facial Nerve Decompression in Complete Bell's Palsy: A Systematic Review and Meta-Analysis

Abstract

We compared the therapeutic efficacy of facial nerve decompression (FND) and conservative treatment in patients with Bell's palsy through a systematic review and meta-analysis. Primary database search was performed in PubMed, Medline, and Embase. After screening, 13 studies were assessed for their eligibility. Among them, seven studies employing either the House-Brackmann grading system (HBGS) or May's classification (modified HBGS) were selected for quantitative and qualitative analysis. Based on May's classification, the degree of recovery was classified into complete (HBGS I), fair (HBGS II-III), or failed (HBGS IV-VI) recovery. The outcomes were assessed between 6 and 12 months after surgery. The estimated pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using random effects model. Cohorts were comprised of patients who underwent FND (n=202, 53.0%) and conservative treatments (n=179, 47.0%). In pooled analysis, the rate of complete recovery was significantly higher in the FND group than in the control group (OR, 2.06; 95% CI, 1.22 to 3.48; P=0.007) showing neither heterogeneity nor publication bias. Meanwhile, the rates of fair recovery (OR, 0.71; 95% CI, 0.42 to 1.21; P=0.208) and failed recovery (OR, 0.60; 95% CI, 0.22 to 1.67; P=0.327) in the FND group were similar to that in the control group. In subgroup analyses, there was no significant difference in the OR according to the operation timing and surgical approach. FND can be a possible treatment option for patients with complete Bell's palsy, especially for complete recovery, which provide insights on decision-making and outcome prediction. However, FND should be determined carefully given the risk of small study effects and possible complications.

Keywords: Bell Palsy; Facial Nerve Decompression; Meta-Analysis.

Fig. 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram outlining the study design. HBGS, House-Brackmann grading system.

Fig. 2.

Comparison of the rate of complete recovery. (A) Forest plot comparing the rate of complete recovery between facial nerve decompression (experimental) and conservative treatment (control) using the odds ratio (OR) and 95% confidence interval (CI). Events represent the number of cases with complete recovery based on May’s classification. (B) Symmetry based on funnel plot suggesting no publication bias. (C) Sensitivity analysis.

Fig. 3.

Comparison of the rate of fair and failed recovery. Forest plots comparing the rate of (A) fair recovery and (B) failed recovery between facial nerve decompression (experimental) and conservative treatment (control) using the odds ratio (OR) and 95% confidence interval (95% CI). Events were based on May’s classification.

Fig. 4.

Comparison of the House-Brackmann grading scores. (A) Forest plot comparing the House-Brackmann grading scores between facial nerve decompression (experimental) and conservative treatment (control) based on the standardized mean difference (SMD). (B) Adjusted publication bias after applying the trim-and-fill method. SD, standard deviation; CI, confidence interval.

Fig. 5.

Subgroup analyses according to operation timing. Forest plot comparing the recovery of facial nerve function according to the operation timing (early intervention: <14 days after onset vs. delayed intervention: >14 days after onset). (A) Complete recovery. (B) Fair recovery. (C) Failed recovery. OR, odds ratio; CI, confidence interval.

Fig. 6.

Subgroup analyses according to surgical approach. Forest plot comparing the recovery of facial nerve function according to the surgical approach (transmastoid approach vs. middle fossa approach). (A) Complete recovery. (B) Fair recovery. (C) Failed recovery. OR, odds ratio; CI, confidence interval.