Effect of early activation of cochlear implant on electrode impedance in pediatric population

Objectives: To assess the evolution of electrode impedance after the early fitting of audio processors (activation after one-day) and classical fitting (activation after one-month) over an up-to-one year after cochlear implant (CI) surgery. Methods: A retrospective cohort study on Fifty-two CI recipients divided into two groups. The study group included 24 recipients (40 ears) who underwent early fitting, whereas the control group contained 28 recipients (40 ears) who underwent classical fitting. The electrode impedance was recorded during the surgery, switch-on session and at one, three, six, and twelve-months after the surgery. Results: In the study group, electrode impedance values obtained intraoperatively and at switch-on and one, three, six, and twelve-months were 4.89, 3.69, 6.52, 6.24, 6.05, and 5.81 K Omega, respectively, and only the switch-on and one-month values were significantly different (p < 0.0001). In the control group, electrode impedance values obtained intraoperatively and at switch-on and one, three, six, and twelve-months were 4.71, 7.19, 6.40, 6.05, and 5.73 K Omega, respectively. Thus, the electrode impedance value at switch-on was 52.65% (p < 0.001) greater than it intraoperatively. For both groups, the electrode impedance value at twelve-months was significantly higher than the respective intraoperative values (study group: 18.6% higher, P = 0.04; control group: 21.65% higher, P = 0.0001). Conclusion: Electrode impedance was significantly lower in the study group compared to the control group until one month after the surgery. However, the electrode impedance at twelve-months after the CI was similar in both groups.