Phoneme discrimination and localization performance in children with cochlear implants and contralateral auditory brainstem implants with inner ear malformations.

Abstract

Purpose: This study compares unilateral and bilateral phoneme discrimination (PD) and azimuth localization abilities in children with severe inner ear malformations and cochlear nerve deficiencies who use a cochlear implant (CI) and a contralateral auditory brainstem implant (ABI).

Methods: A total of 17 children between the ages of 7 and 18 years with CI and contralateral ABI were included in the study. PD and localization tests were evaluated in three conditions: CI only, ABI only, and bilateral. All subjects completed a self-report Hearing-Related Quality of Life (HRQoL) scale.

Results: Statistical analysis revealed that PD scores were significantly higher in the bilateral condition than in the ABI condition alone (p = 0.003). However, no significant differences were found between the CI and ABI or between the CI and bilateral conditions. Similarly, no statistically significant differences in localization performance were found between the three conditions (p > 0.05). Regression analysis identified HRQoL as a significant predictor of bilateral PD (p < 0.05), while ABI localization was a significant predictor of bilateral localization (p < 0.05). Additionally, bilateral PD was found to be a significant predictor of HRQoL (p = 0.001).

Conclusion: While the performance of CI alone and bilateral PD is similar, there is a significant difference between the performance of ABI alone and bilateral PD. Therefore, in cases with an ABI, bilateral stimulation should be maintained by continued use of a CI in the contralateral ear, even in the presence of severe inner ear malformation and/or cochlear nerve deficiencies. In the long term, comparable levels of PD discrimination and localization performance can be achieved by using two different modalities.