MM111 - Impact of Cochlear Implant Electrode Scala Placement on Post Operative Speech Perception

Abstract: Cochlear implant (CI) outcomes vary widely, and electrode array design is one modifiable factor of growing clinical interest. Previous studies comparing peri-modiolar and lateral wall arrays have yielded mixed results, often limited by inconsistent methodologies and follow-up intervals. This presentation will synthesize findings from the broader literature and present emerging data from a multi-center Mayo Clinic cohort examining speech perception outcomes at 3-, 6-, 12-, and 24-months post-implantation. Preliminary analyses suggest peri-modiolar arrays may confer long-term advantages. By integrating prior research with new evidence, we will highlight practical implications for array selection and surgical planning.

Summary: Cochlear implants (CIs) are a well-established intervention for severe to profound sensorineural hearing loss, yet considerable variability remains in postoperative speech perception outcomes. While demographic and etiological factors contribute to this variability, electrode array design represents a modifiable factor that may contribute to patient outcomes. The literature comparing peri-modiolar and lateral wall arrays has grown in recent years, yet studies evaluating outcomes between designs has produced mixed results. Some studies report superior outcomes for peri-modiolar arrays due to closer modiolar proximity, while others highlight advantages of lateral wall designs in hearing preservation. Methodological differences, including heterogeneous cohorts, variable measures, and non-standardized follow-up, limit generalizability.
The purpose of this presentation is to (1) to review and critically evaluate existing literature comparing peri-modiolar and lateral wall arrays, and (2) to present emerging results from a large, multi-center Mayo Clinic cohort. By integrating past findings with new data, we aim to provide clinicians with evidence-based guidance for array selection.
Methods and Cohort Description
Our retrospective cohort includes adult CI recipients implanted at three Mayo Clinic sites (Arizona, Florida, Rochester) between 2020 and 2024. Demographic and clinical variables are extracted from electronic medical records, with IRB approval for chart review. Speech perception outcomes are measured at standardized postoperative intervals—3, 6, 12, and up to 24 months—using single-word and sentence recognition tests. Statistical analyses include descriptive comparisons, ANOVA, and multivariable modeling to control for confounders such as age and pre-implant ability.
Synthesis of Prior Literature
Two main themes emerge in the literature. First, peri-modiolar arrays may improve channel selectivity and reduce current spread, theoretically enhancing long-term performance. Second, lateral wall arrays, while positioned farther from the modiolus, may preserve residual hearing and reduce insertional trauma. Large-scale studies often report no difference in early outcomes, suggesting peri-modiolar benefits may emerge only over longer follow-up. These nuances underscore the importance of standardized longitudinal data collection—an area our cohort seeks to address.
Preliminary Findings
Consistent with prior reports, our early data show little difference between groups at 3- and 6-months post-implantation. However, at 12 months and beyond, peri-modiolar recipients appear to demonstrate superior speech perception scores. These emerging trends support the hypothesis that closer modiolar proximity enhances neural stimulation efficiency over time.
Clinical Impact and Takeaways
By situating new data within the context of prior evidence, this presentation will offer a balanced, clinically actionable perspective. Attendees will learn:
1. The strengths and limitations of existing studies on electrode array design.
2. How consistent methodologies and multi-center data improve interpretability.
3. Practical considerations for electrode array selection, including when peri-modiolar arrays may be advantageous for long-term performance versus when lateral wall designs may remain appropriate.
Conclusion
Electrode array design represents a key, modifiable factor in optimizing CI outcomes. By combining a literature review with emerging multi-center data, this presentation highlights both the current state of knowledge and future directions in evidence-based CI surgical planning. Ultimately, these insights may contribute to more predictable and durable improvements in speech perception for CI recipients.

Brief Summary of Clinical Takeaways: Electrode array design can affect long-term cochlear implant outcomes. Peri-modiolar arrays may offer advantages beyond 12 months, while lateral wall designs remain useful for hearing preservation. Tailoring array choice to patient profile can optimize auditory outcomes.

Assumptions: Learners should be familiar with cochlear implant candidacy, basic inner ear anatomy, and standard speech perception outcome measures to fully interpret literature comparisons and emerging clinical data.