Science Spotlight: Global Insights on the Importance of the Electrode-Neural Interface

Optimizing long-term hearing outcomes begins with understanding how electrode design and placement influence cochlear implant (CI) performance. Recent innovations emphasize the critical role of the electrode-neural interface, with slim perimodiolar arrays offering more targeted stimulation of the spiral ganglion, potentially improving speech understanding and preserving residual hearing. A recently published expert review titled, “The Importance of the Electrode-Neural Interface in Supporting Long-Term Outcomes in Cochlear Implantation: Expert Opinion,” brings together insights from leading CI surgeons across Europe, Asia, Australia and the United States, collectively caring for over 30,000 patients¹. Prioritizing clinically relevant studies from the past decade, the experts focused on contemporary electrode designs and robust sample sizes to highlight the factors that truly impact patient outcomes and guide confident surgical decision-making and counseling.

Key evidence to support expert consensus:

• Modiolar proximity improves speech perception:
  • In a study of 59 CI recipients, closer proximity to the modiolus was significantly correlated with higher CNC word scores²
  • Patients with slim perimodiolar arrays showed 75% correct electrode discrimination, compared to 41.6% with lateral wall arrays³
• Slim perimodiolar arrays support consistent scala tympani placement:
  • A multicenter study reported 0% translocation with sheath-based slim modiolar arrays vs. 18% with older stylet-based arrays⁴
  • Insertion trauma grades of 0 (no trauma) were achieved in 95–98% of cases with slim modiolar arrays⁵
• Preserving cochlear health is essential for sustained CI performance:
  • Deeper lateral wall insertions (> 450°) were associated with higher trauma risk and poorer speech discrimination⁶
  • Ishiyama et al. (2018) observed erosive changes in the lateral wall in postmortem analyses of patients with lateral wall electrodes, suggesting that perimodiolar designs may avoid secondary degeneration and better preserve cochlear health over time.⁷

This international expert consensus review emphasizes that electrode-neural interface quality and cochlear health preservation are critical to long-term CI outcomes. Slim perimodiolar arrays, designed to sit closer to the modiolus, enable focused stimulation, lower thresholds, and reduced channel interaction—all contributing to improved speech understanding.

At the same time, these arrays protect cochlear structures by avoiding deep insertions that risk trauma to the lateral wall and basilar membrane. This expert review reinforces Cochlear’s design philosophy which is to fit the electrode to the natural shape of the cochlea, enabling closer proximity to the neural elements. While individual factors like etiology, duration of deafness and age modestly predict cochlear implant outcomes, the evidence consistently shows that perimodiolar arrays, when placed fully in the scala tympani, are associated with superior speech perception.

Ultimately, the quality of the electrode-neural interface is a critical determinant of cochlear implant performance, especially as patients rely on their cochlear implants for hearing over a lifetime. For more information, read the full expert opinion article here.

1. Ramos-Macias Á, Briggs R, Choi BY, Friedmann D, Ishiyama A, Lenarz T, Mylanus E, O’Leary S, Roland JT Jr, Zarowski A. The Importance of the Electrode-Neural Interface in Supporting Long-Term Outcomes in Cochlear Implantation: Expert Opinion. Audiol Neurootol. 2025 Apr 23:1-11. doi: 10.1159/000546003. Epub ahead of print. PMID: 40267898.
2. Holden, L.K., Finley, C.C., Firszt, J.B., et al. (2013). Factors Affecting Open-Set Word Recognition in Adults with Cochlear Implants. Ear and Hearing, 34(3), 342–360. https://doi.org/10.1097/AUD.0b013e3182741aa7
3. Ramos-de-Miguel, Á., Argudo, A.A., Borkoski-Barreiro, S.A., et al. (2018). Imaging Evaluation of Electrode Placement and Effect on Electrode Discrimination on Different Cochlear Implant Electrode Arrays. European Archives of Oto-Rhino-Laryngology, 275, 1385–1394. https://doi.org/10.1007/s00405-018-4943-2
4. Shaul, C., Weder, S., Tari, S., et al. (2020). Slim Modiolar Cochlear Implant Electrode: Melbourne Experience and Comparison with the Contour Perimodiolar Electrode. Otology & Neurotology, 41(5), 639–643. https://doi.org/10.1097/MAO.0000000000002617
5. Iso-Mustajärvi, M., Sipari, S., Löppönen, H., & Dietz, A. (2020). Preservation of Residual Hearing After Cochlear Implant Surgery with Slim Modiolar Electrode. European Archives of Oto-Rhino-Laryngology, 277, 367–375. https://doi.org/10.1007/s00405-019-05708-x
6. Ketterer, M.C., Aschendorff, A., Arndt, S., & Beck, R. (2022). Electrode Array Design Determines Scalar Position, Dislocation Rate and Angle and Postoperative Speech Perception. European Archives of Oto-Rhino-Laryngology, 279(9), 4257–4267. https://doi.org/10.1007/s00405-021-07160-2
7. Ishiyama A, Lopez I, Ishiyama G, Linthicum F. A modiolar position helps to avoid secondary changes to the lateral wall over the long term. In: Presented at the American Otological Society meeting; 2018.

This blog is intended to serve as a resource for clinicians to help keep up to date with current clinical literature and is intended for professionals only. Clinical literature is based on research, which may include the experimental use of new or currently available products and technologies. Therefore, literature presented on this blog may represent use of Cochlear products that does not align with the intended use or indications approved by regulatory bodies, also known as off-label use. Cochlear does not condone any off-label use of its products, and it is not Cochlear’s intent to promote off-label use by providing this blog as a resource to health professionals.