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.
A systematic search was conducted in PubMed, Embase, and Cochrane Library. Only articles in English were included.
Prospective studies published until January 2018 on hearing preservation
methods were included.
Studies were assessed on unaided pre- and postoperative hearing thresholds, follow up time, and methodological quality.
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.