Prognostic factors for long-term hearing preservation after canal-tympanoplasty for congenital aural atresia

The present study aimed to determine favorable prognostic factors for long-term postoperative hearing outcome after canal-tympanoplasty for congenital aural atresia (CAA). We retrospectively reviewed pre and postoperative hearing results and image findings of 51 ears with CAA performed by canal-tympanoplasty for primary repair. Averages of the postoperative air and bone-conduction thresholds, and the air–bone gap (ABG) were calculated from the last pure-tone audiometry. Follow-up duration ranged from 16 to 139 months. A successful hearing result was defined as a postoperative ABG of ≤15 dB, or a postoperative pure-tone average of ≤30 dB. The influence of the following factors on the success of surgery was assessed by multivariate logistic regression analysis: total Jahrsdoerfer grading system score, age at surgery, and dimensions of middle ear including incudostapedial joint angulation, mesotympanic height, mesotympanic width, mesotympanic depth, mesotympanic area, mesotympanic volume, reconstructable external auditory canal (EAC) diameter, and reconstructable EAC height. Successful hearing outcomes were achieved in 24 of 51 ears (47.1 %). A multivariate logistic regression analysis showed that an EAC area >72.3 mm² was the most significant favorable predictive factor (P = 0.006), followed by mesotympanic depth >5.5 mm (P = 0.013), mesotympanic height >4.6 mm (P = 0.016), and EAC diameter >9.5 mm (P = 0.029). In conclusion, the size of the reconstructable EAC and mesotympanum is important for predicting long-term favorable hearing outcome following canal-tympanoplasty for CAA.