Hearing Preservation of Slim Modiolar and Slim Straight Electrodes: A Systematic Review and Meta-Analysis

This meta-analysis aims to investigate the hearing preservation (HP) rates of slim straight electrodes (SSE) and slim modiolar electrodes (SME) after cochlear implantation, in the short- and long-term (≤4 months and 4-12 months, respectively).

A systematic search was conducted in PubMed, Embase, Cochrane Library, and ClinicalTrials databases for studies published between 1 January, 2014, and 1 January, 2024. Cohort studies, case series, and randomized controlled trials written in English, reporting HP rates using the HEARRING classification system, were included.

Sixteen studies were included, comprising 15 observational studies and 1 randomized controlled trial. The overall short-term HP rate for SSE was 68.70% (95% CI: 52.27-85.12%), which decreased to 56.38% (95% CI: 42.87-69.90%) in the long-term. In contrast, SME maintained stable HP rates of 59.07% (95% CI: 50.03-68.10%) in the short-term, and 59.09% (95% CI: 46.48-71.70%) in the long-term.

The meta-analysis revealed that SME and SSE have a similar HP ability in both the short- and long-terms. Notably, a prominent decline in HP rate over time was observed in the SSE compared with SME.