Angular Electrode Insertion Depth and Speech Perception in Adults With a Cochlear Implant: A Systematic Review

Area of Science:

• Otolaryngology
• Neurosurgery
• Audiology

Background:

• Cochlear implantation (CI) is a treatment for severe to profound hearing loss.
• The electrode insertion depth within the cochlea may influence speech perception outcomes.
• Determining the optimal electrode position is crucial for maximizing CI efficacy.

Purpose of the Study:

• To systematically review existing literature on the relationship between angular insertion depth and speech perception in cochlear implant users.
• To summarize the current evidence regarding the influence of CI electrode position on hearing outcomes.
• To identify potential factors contributing to optimal CI electrode placement.

Main Methods:

• A comprehensive literature search was conducted across multiple databases (PubMed, EMBASE, Web of Science, Cochrane Library) up to June 2018.
• Seven studies investigating adult cochlear implant recipients with normal cochlear anatomy were included.
• Studies were assessed for quality and risk of bias using the QUIPS tool; meta-analysis was not feasible due to heterogeneity.

Main Results:

• Six of the seven included studies reported no statistically significant effect of angular insertion depth on speech perception.
• The quality of included studies was generally low-to-moderate with a high risk of bias.
• Significant heterogeneity among studies precluded meta-analysis, with individual study findings presented.

Conclusions:

• Methodological limitations in the current body of research prevent definitive evidence-based conclusions.
• Further high-quality studies are needed to establish the influence of angular insertion depth on speech perception after cochlear implantation.
• The optimal cochlear implant electrode position remains undetermined based on available evidence.