To examine the results of hearing preservation in cochlear implantation surgery to identify surgical technical factors, electrode array design factors, and steroid usage, which predicts greater low-frequency hearing preservation.
A thorough search of Medline and Pubmed of English studies from January 1, 1995, to January 1, 2013, was performed using the key words “electric and acoustic hearing” or “hybrid cochlear implant” or “EAS cochlear implant” or “partial deafness cochlear implant” or “bimodal hearing cochlear implant” or “hearing preservation cochlear implant.”
The meta-analysis was conducted according to the PRISMA statement. Only articles in English were included. Studies were included if hearing preservation was the primary end point. A final number of 24 studies met the inclusion criteria.
Patient populations were analyzed as intention to treat. Data were extracted from raw audiograms where possible. Data were excluded if not all explanatory variables were present or if variable values were ambiguous.
The weighted least-squares regression method was used to determine the predictive power of each explanatory variable across all studies.
In this meta-analysis, the following are associated with better hearing preservation: cochleostomy over the round window approach, posterior tympanotomy over the suprameatal approach, a slow electrode array insertion technique over insertion of less than 30 seconds, a soft tissue cochleostomy seal over a fibrin glue only seal and the use of postoperative systemic steroids. Longer electrode arrays, topical steroid use, and lubricant use for electrode array insertion did not give an advantage.