Purpose: To evaluate the impact of sequential second CI on the electrophysiological parameters of the initial CI.
Methods: Totally, 30 children who received sequential CIs between January and July 2018 were included in the study. All patients received the same brand of CI (Advanced Bionics, HIRES 90K Advantage 1J). Of 16 CI electrodes, 3rd (E3), 7th (E7) and 11th (E11), and 15th (E15) electrodes which were corresponding to the apical, middle, and basal cochlea were used in the measurements. The tNRI, electrode impedance and M levels were recorded as the contralateral CI was switched off and on, respectively.
Results: As the second CI was switched off, the impedance, tNRI and M values of initial CI 1st, 3rd and 6th months were not significantly different (p > 0.05). There was a significant difference between the impedance, tNRI and M values of initial CI as the second CI was switched on (p < 0.05).
Conclusion: Activation of the sequential second CI leads to a decrease in the tNRI and M levels of the initial CI. This condition can increase the efficiency obtained by CIs. However, these changes should be remembered during CI programming.
Keywords: ECAP; Electrode impedance; M level; Sequential cochlear implant.