Hearing Preservation: Does Electrode Choice Matter?

Objective: Evaluate if electrode design affects hearing preservation (HP) following cochlear implantation (CI) with full-length electrodes. Study Design: Case series with chart review. Setting: Tertiary referral academic center. Subjects and Methods: Forty-five adults with low-frequency hearing (≤85 dB at 250 and 500 Hz) who underwent unilateral CI with full-length electrode arrays made by 1 manufacturer were included. HP was calculated with (1) mean low-frequency pure-tone average (LFPTA) at 250 and 500 Hz (MEAN method), (2) a percentile method across the audiometric frequency spectrum generating an S-value (HEARRING method), and (3) functional if hearing remained ≤85 dB at 250 and 500 Hz. Audiometric testing was performed approximately 1 month and 1 year postoperatively, yielding short-term and long-term results, respectively. Results: Of 45 patients who underwent CI, 46.7% received lateral wall (LW) and 53.3% received perimodiolar (PM) electrodes. At short-term follow-up, LW electrodes were associated with significantly better HP than PM (LFPTA method: 27.7 vs 39.3 dB, P <.05; S-value method: 48.2 vs 21.8%, P <.05). In multivariate regression of short-term outcomes, LW electrode use was a significant predictor of better HP (P <.05). At long-term follow-up, electrode type was not associated with HP. Younger patient age was the only significant predictor of long-term HP on multivariate analysis (P <.05). Conclusion: The LW electrode is associated with short-term HP, suggesting its design is favorable for limiting trauma to the cochlea during and directly following CI. Other factors, including age, are relevant for maintaining HP over the long term. The data support further investigation into what modifiable factors may promote long-term HP.