Abstract
Reducing electrode impedance is an important factor in improving the functional benefits of cochlear implants (CIs). The immediate effect of early switch-on within 24 h of surgery on impedance among CI recipients with various types of electrodes has been reported previously; however, the immediate change and the evolution of electrode impedances of slim modiolar electrodes after early switch-on within 24 h of implantation has not. Therefore, the focus of this retrospective cohort study of CI patients was to compare the effect of early switch-on (n = 36) and conventional switch-on (n = 72) 2–4 weeks post-operation on impedance. Compared with impedance measured intraoperatively, our results demonstrate a significant decrease in impedance from 11.5 to 8.9 kΩ (p < 0.001) at 2–4 weeks after implantation in the early switch-on group, which sharply contrasted with elevated impedance values for conventional switch-on 2–4 weeks after implantation (from 10.7 to 14.2 kΩ, p = 0.001). Notably, a comparatively lower impedance than the conventional switch-on protocol was observed for up to 2 months post-operation. Most importantly, a much earlier stabilization of impedance can be achieved with the early switch-on protocol coupled with the slim modiolar electrode array compared to the conventional switch-on protocol, offering the advantage of reducing the number of required mapping sessions in the early stages of rehabilitation.
Highlights
Reducing electrode impedance is an important factor in improving the functional benefits of cochlear implants (CIs)
Because there were no significant differences between the two modes, here we primarily reported the impedance under the monopolar 2 (MP2) mode (Table 1), and the detailed impedance values under the common ground (CG) mode were provided in supplementary Table S1
Comparison of longitudinal changes in electrical impedance of slim modiolar electrodes depending on the timing of the initial switch‐on
Summary
Reducing electrode impedance is an important factor in improving the functional benefits of cochlear implants (CIs). A much earlier stabilization of impedance can be achieved with the early switch-on protocol coupled with the slim modiolar electrode array compared to the conventional switch-on protocol, offering the advantage of reducing the number of required mapping sessions in the early stages of rehabilitation. Owing to the compliance voltage limit of the CI device, the maximum current that can be delivered to the electrode contacts with high impedance values is necessarily reduced, which in turn decreases the dynamic range of the current stimulation. Atraumatic insertion is an important prerequisite for minimizing the increase in electrode impedance levels, since inflammatory responses after mechanical trauma have been considered the primary cause of cochlear fibrosis and o ssification[11,12]. Seoul National University Bundang Hospital, Seoul National University College of Medicine, 300 Gumi‐dong, Bundang‐gu, Seongnam 13620, Republic of Korea. 3These authors contributed : Woongsang Sunwoo and Scientific Reports | (2021) 11:22809
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