Facial Canal Dehiscence: Systematic Review and Meta-analysis of Prevalence in Healthy Subjects

Purpose: A thorough understanding of facial canal dehiscence (FCD) is imperative for informed consent before otological surgery. A broad range of published rates for FCD exists, varying by method of assessment, location along the canal, and year of investigation. This study aims to determine a clinically relevant prevalence of FCD in healthy populations. Methods: A systematic review of Embase, Medline, Cochrane Library, Google Scholar, Science Direct, and Scopus identified eligible studies reporting the prevalence of FCD in subjects aged 10 years or older without erosive bone disease. Prevalence, location of dehiscence, and method of assessment were extracted. Pooled prevalence was calculated using a random-effects model with the generic inverse variance method. Results: A total of 2186 unique studies provided 52 eligible cohorts for analysis (15,090 facial canals). The overall pooled prevalence of FCD was 22% (95% CI: 17%-28%). Pooled prevalence of dehiscence in the tympanic segment varied significantly by method of assessment ( P = 0.0494): radiologic imaging 32% (95% CI: 15%-55%), cadaveric dissection 23% (95% CI: 14%-35%), and intraoperative finding 7% (95% CI: 1%-29%). Conclusion: This is the first clinically focused and comprehensive estimate of FCD in nonerosive ears of healthy subjects. The rate from cadaveric studies showed dehiscence in ~2 in 10 ears, whereas CT was higher at ~3 in 10, and intraoperative findings were lowest at ~1 in 10. Understanding these variations in reported rates of FCD has direct implications for preoperative risk assessment, patient counseling, and surgical planning in otological practice.