Hearing preservation in cochlear implant surgery : a meta-analysis

Objective(s): The aim of the present meta-analysis is to assess the effects of hearing preservation (HP) methods on residual hearing in patients undergoing cochlear implant (CI) surgery and to look at the effect of follow-up time on HP outcome. Data Sources: A systematic search was conducted in PubMed, Embase, and Cochrane Library. Only articles in English were included. Study Selection: Prospective studies published until January 2018 on hearing preservation methods were included. Data Extraction: Studies were assessed on unaided pre- and postoperative hearing thresholds, follow up time, and methodological quality. Data Synthesis: A random-effects meta-regression was performed for the HP outcome in relation to surgical technique, electrode array design, inserted electrode length, insertion speed, and corticosteroid use for different follow up times (1 month, 6 months, and 12 months or more postoperatively). Conclusion: Hearing preservation in cochlear implant surgery is feasible. A statistically significant difference was found between the round window procedure and cochleostomy approach, in favor of the round window procedure at 6 months postoperatively (p = 0.001). A statistically significant difference was found between the straight and the perimodiolar electrode array at 1 month postoperatively in favor of the straight electrode array (p < 0.001). No statistically significant difference was found between the other HP methods. The round window approach with the straight electrode array might result in a better HP outcome at 1 month and 6 months postoperatively compared with the cochleostomy approach with the perimodiolar electrode array. A declining trend in HP outcome in both combinations was seen over time