Clinico-radiological predictors of facial palsy incidence after transcanal cochlear implantation: an ambispective multicenter study

Objective To assess the incidence, risk factors, and outcomes of facial palsy following cochlear implantation using the transcanal technique, incorporating radiological predictors. Methods An ambispective observational study involving 978 patients who underwent cochlear implantation via the transcanal technique at three tertiary academic referral center from January 2014 to December 2024. Radiological parameters measured on preoperative computed tomography (CT) scans included facial nerve annulus distance (FAD), facial nerve-round window distance (FNRWD), facial recess width (FRW), alpha angle, and beta angle. Clinical data, including demographics, intraoperative details, and postoperative facial nerve function, were recorded. Results Facial palsy occurred in 7 out of 978 patients (0.71%), all were prelingually deaf children under five years old. Six out of seven had immediate onset facial palsy, with House-Brackmann grades IV-VI. In the non-facial palsy group (n = 971), mean radiological values were: FAD 7.12 mm (+/- 1.08), FRW 4.52 mm (+/- 0.67), and Alpha angle 51.2 degrees (+/- 4.3 degrees). In the facial palsy group (n = 7), values were 7.05 mm (+/- 1.15), 4.48 mm (+/- 0.73), and 50.1 degrees (+/- 3.9 degrees), with no significant differences between the groups. Conclusion Facial palsy following the transcanal technique is a rare complication, with an incidence of less than 1 in 100 patients. While reduced FRW and FAD were explored as potential contributors, no statistically significant risk factors could be established.