Extratemporal facial nerve branching patterns: systematic review of 1497 cases

Objective. The aim of this systematic review was to analyse the complex anatomy of the extratemporal portion of the facial nerve with an accurate description of the branching patterns based on the Davis classification. Method. Medline, ScienceDirect and the Cochrane Library databases as well as other sources were searched by two independent reviewers. Results. Analysis of 21 studies with a total of 1497 cases showed that type III is the most common branching pattern accounting for 26.8 per cent of cases. The type I pattern, previously considered as the normal anatomy in most textbooks, was the fourth most common branching pattern at 16.3 per cent. The majority of specimens (96.4 per cent) were found to have a bifurcated main trunk, and only 3.2 per cent were found with a trifurcated main trunk. Conclusion. Surgeons should be aware of anatomical variations in the course of the facial nerve. An early identification of the branching pattern during surgery reduces the risk for iatrogenic facial nerve injury.