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. 2025 Jun 18:16:1599369.
doi: 10.3389/fneur.2025.1599369. eCollection 2025.

The influence of CI electrode array design on the preservation of residual hearing

L Fries  1 , F Everad  1 , R L Beck  1 , A Aschendorff  1 , S Arndt  1 , M C Ketterer  1
Affiliations

The influence of CI electrode array design on the preservation of residual hearing

L Fries et al. Front Neurol. .

Abstract

Objectives: To individualize cochlear implant (CI) surgery regarding cochlear morphology, different electrode arrays have been developed. The study aims to investigate the influence of the electrode array design on the preservation of residual hearing, considering long-term results.

Methods: We performed a retrospective analysis of 923 patients implanted with straight or perimodiolar electrode arrays from Cochlear™ and MED-EL between 2003 and 2021. The standard pure tone average (PTA4) and low-frequency PTA (PTAlow) were measured before and after surgery, with a follow-up period of 3.2 years up to 15.7 years.

Results: In patients with measurable preoperative PTA4 (data of four frequencies), the slim straight electrode array (SSA) was chosen significantly more often preoperatively within the Cochlear™ portfolio (CA vs. SSA p = 0.007) and the Flex24 within the MED-EL portfolio (FlexSoft vs. Flex24 p = 0.0085). The electrode array design significantly influences the preservation of residual hearing, both in low-frequency PTA and standard PTA. The electrode arrays with the most favorable performance in terms of long-term residual hearing preservation appear to be the slim straight electrode array (SSA) from Cochlear™ and the Flex24 from MED-EL, with no statistical differences from other electrodes.

Conclusion: Preoperative residual hearing influences the choice of electrode array within the manufacturer's portfolio, with short electrode arrays showing superior results in the preservation of residual hearing. Over time, straight and short electrode arrays are associated with improved preservation of residual hearing. Therefore, for patients with existing relevant residual hearing, it is advisable to choose short and atraumatic lateral wall electrode arrays.

Keywords: cochlear implant; electrode; electrode array design; residual hearing preservation; speech perception.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Flowchart of patient cohort (total cohort n = 923).
Figure 2
Figure 2
Preoperative PTA4 curves demonstrate the significant influence of the surgeon’s electrode array choice depending on the patient’s choice of manufacturer (n = 324) (** FlexSoft vs. Flex24 p = 0.0085; ***CA vs. SSA p = 0.007).
Figure 3
Figure 3
Preoperatively assessed PTAlow (dB) in the sub-cohort of 233 patients shows no statistical difference comparing the selected electrode arrays.
Figure 4
Figure 4
Distribution of hearing loss across frequencies from 125 to 10,000 Hz in the study cohort of 923 ears.
Figure 5
Figure 5
Kaplan–Meier analysis of all included electrode arrays meeting the preoperative inclusion criteria for the PTA4 sub-cohort (n = 324).
Figure 6
Figure 6
Kaplan–Meier analysis of all included electrode arrays meeting the preoperative inclusion criteria for the PTAlow sub-cohort (n = 233).
See this image and copyright information in PMC

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