Comparison of the Outcomes of Lateral Wall, Perimodiolar, and Midscala Electrodes in Cochlear Implantation Surgery: A Meta-Analysis.

Introduction: Cochlear implant (CI) is the standard of care for most cases of severe-to-profound hearing loss. Different electrodes are available for CI. Objective: To compare the lateral wall, midscala, and perimodiolar electrodes in CI surgery in terms of trauma to the cochlea and hearing preservation (if there is residual hearing). Data Synthesis: We performed a comprehensive search on the PubMed/MEDLINE, Scopus, Web of Science, and Cochrane Library databases in June 2022 for articles in the literature published until this year. We included studies published in English, involving human subjects, and regarding the types of electrodes in CI surgery, and we excluded laboratory and opinion studies. The current review followed the guidelines of the 2009 Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. We found 21 studies; the hearing preservation rates with each electrode were as follows: lateral wall electrode - 53%; perimodiolar electrode - 35%; and midscala electrode - 58%. The lateral wall and midscala electrodes presented better preservation of residual hearing than the perimodiolar electrode. The rates of cochlear trauma with each electrode were as follows: lateral wall electrode - 61%; perimodiolar electrode - 29%; and midscala electrode - 16%. Conclusion: The rates of preservation of functional residual hearing in CI are higher in lateral wall and midscala electrodes than in perimodiolar electrodes.