Electrode Impedance Fluctuations and Sudden Decline in Cochlear-Implant Benefit

The main objective of this clinical capsule was to outline the narrative of three teen cochlear implant (CI) users who experienced a sudden increase in their CI electrode impedance values, which coincided with decreased overall speech perception ability. In addition, the study explored the following questions: Are there any similarities between cases? What recommendations should be made for continuing treatment regarding these cases?

Three teenagers who reported sudden change in CI benefit were included in this study.

Electrode impedance values and speech identification scores were obtained routinely during the CI mapping appointments. Specifically, word and sentence recognition scores were obtained using the Consonant-Nucleus-Consonant word list and the AZBio sentence test, respectively. Both patient 1 and patient 2 underwent CI reimplantation operations as a result of their perceived difficulties and decreased impedances. Patient 3 did not undergo reimplantation surgery.

All three patients' CI electrode impedances and speech perception scores eventually stabilized over time. No relationship could be drawn between revision surgery and stabilization of CI electrode impedances and speech perception scores.

Overall, we found no similarities between cases that could potentially explain the sudden electrode impedance value increase or the decrease in speech perception scores. Each case should be evaluated uniquely and carefully for CI revision operations by frequent monitoring, including mapping and speech perception testing. The most common factor contributing to each teen's eventual resolution of electrode impedance values and speech perception scores was time.