ORIGINAL RESEARCH article
Front. Immunol.
Sec. Inflammation
Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1702549
This article is part of the Research TopicExploring Immunological Factors in Inner Ear Disorders: Allergy and InflammationView all 4 articles
Electrode Impedance Dynamics in Sequential Cochlear Implant Users: Insights into Cochlear Immunity
Provisionally accepted
- 1Department of Otolaryngology-Head and Neck Surgery, University of Iowa Health Care Medical Center, Iowa City, IA, United States
- 2Department of Biostatistics, University of Iowa, Iowa City, IA, United States
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Introduction: Cochlear implant outcomes can be limited secondary to immunologically-mediated intracochlear foreign body responses resulting in new bone growth and fibrosis. Minimal consideration has been given to possible immunological memory modulating this response in sequentially-implanted patients. We hypothesize the first implant primes the contralateral ear to more robustly respond to sequential implantation, leading to earlier increases in electrode impedance. Methods: This is a retrospective cohort analysis of clinical impedance measurements from 79 subjects with sequential bilateral implants. Raw impedance and impedance changes were considered across time by implant sequence. Results: Paired t-tests comparing 12-month average absolute impedance between implants were statistically significant (22 electrodes, p = 0.0176, 95% CI (-731.37,-71.84); excluding 5 basal electrodes, p = 0.0070, 95% CI (-784.31,-128.40)). Linear mixed models showed significant effects at p < 0.0001, including implant sequence, time elapsed, and electrode grouping. Estimated marginal means showed statistically significant differences of delta impedance between all combinations of basal, middle, and apical subsets. Given subset, statistically significant differences in delta impedance by implant sequence were seen in the basal (p = 0.0136) and apical (p = 0.0067) groups. Estimated marginal slopes of delta impedance by implant sequence were also significantly different (p < 0.0001). Discussion: More rapid increases and greater electrode impedances are consistent with a more robust immune response in the second implanted ear. Additional investigation into the impacts of timing between implants, electrode array type, perioperative corticosteroids, and complex impedances may extend understanding of these relationships and their implications on the cochlear immune response.
Keywords: cochlear implant, impedance, Inflammation, immunology, hearing loss prevention, Foreign body response, Immunological memory, Retrospective cohort
Received: 10 Sep 2025; Accepted: 13 Oct 2025.
Copyright: © 2025 Flom, Rasche, Oleson, Scheperle and Hansen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Marlan R Hansen, marlan-hansen@uiowa.edu
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