Classification of facial nerve aberration in congenital malformation of middle ear: Implications for surgery of hearing restoration.

Objectives: Facial nerve aberration is the most troublesome situation in congenital malformations of middle ear. The aim of our study is to investigate its imaging and clinical features as well as relevant choice of surgical techniques for hearing improvement.

Methods: A retrospective study involving review of clinical data of 227 patients (256 ears) with congenital middle ear anomaly was undertaken, including preoperative computed tomography (CT) data, surgical records and videos.

Results: Aberration involving intratemporal facial nerve was found in 82/256 ears (32.03%) with congenital middle ear anomaly. The most common forms of aberration included overhanging over the oval window (50/82 ears, 60.98%), bifurcation (3/82 ears, 3.66%) and transverse over the promontory (3/82 ears, 3.66%), counting for 68.29% (56/82) of the cases with facial nerve aberration. Concomitant stapes malformation was found in 76/82 ears (92.68%) and atresia or stenosis of the oval window in 27/82 ears (32.93%). In 9/82 ears (10.98%) both stapes and oval window was absent. Elective surgeries for the purpose of hearing improvement included stapodotomy + piston implantation, labyrinthotomy, labyrinthotomy + total ossicular replacement prosthesis (TORP) implantation and Vibrant Soundbridge (VSB) implantation.

Conclusion: The majority of facial nerve aberration in congenital malformation of middle ear involves displacement of facial nerve, in addition to concomitant malformations of the stapes and/or oval window, which may influence the choice of surgery for hearing improvement. VSB implantation may be considered as a useful option.