Transcanal Endoscopic Facial Nerve Decompression: Systematic Review and Meta-Analysis of Functional and Auditory Outcomes

Introduction: The transcanal endoscopic approach (TEA) is a minimally invasive technique for facial nerve decompression in post-traumatic temporal bone fractures. These fractures often cause ossicular chain damage and conductive hearing loss, necessitating concurrent ossicular chain reconstruction. Preoperative air-bone gap (ABG) identifies existing damage, while postoperative ABG assesses hearing restoration success. This meta-analysis evaluates the effectiveness of TEA in improving facial nerve function and hearing outcomes.

Methods: Ten studies involving 107 patients were included. Primary outcomes were improvements in House-Brackmann (HB) grade scores and reductions in ABG. Random-effect models calculated pooled estimates, and heterogeneity was assessed using I² and Q-tests. Effect sizes with confidence intervals summarized findings.

Results: Facial nerve recovery showed 85.6% of patients (95% CI: 77%-91%) achieving favorable HB grade outcomes (Grade I-II), demonstrating significant improvement. The analysis revealed an average improvement of 3.9 ± 0.73 in HB scores, indicating consistent enhancement in facial nerve function post-operatively. Hearing outcomes showed moderate improvement (Mean Difference=5.05, 𝑝 < 0.0001), but the high heterogeneity (I²=97.7%) reduced reliability. For ABG reduction, the pooled effect size was -0.90 (95% CI: -3 to 16), reflecting variability likely due to concurrent hearing restoration procedures, such as ossicular chain reconstruction.

Conclusions: TEA demonstrates high success in facial nerve recovery, with 86% of patients achieving favorable HB outcomes. The tympanic segment and geniculate ganglion are the most commonly decompressed portions, with no major intraoperative or postoperative complications. One RCT compared endoscopic and microscopic transcanal approaches, showing complete decompression can be achieved solely with an endoscope. While ABG improvements varied, these findings highlight the effectiveness of TEA and emphasize the need for standardized techniques and further research to optimize its impact on hearing outcomes.