Speech Perception and Sound Localization Skills in Inner Ear Malformations: Children With Incomplete Partition Type-II.

Objective: The present study aimed to evaluate binaural auditory skills in bimodal and bilateral pediatric cochlear implant (CI) users with incomplete partition type-II (IP-II) and to reveal the effect of IP-II on performance by comparing the results to pediatric CI users with normal cochlear morphology.

Study Design: Cross-sectional study.

Setting: Tertiary referral center.

Methods: Forty-one CI users (mean age 8.8 ± 1.9) were grouped as bimodal (BIM-IP) and bilateral (BIL-IP) users with IP-II; bimodal (BIM-N) and bilateral (BIL-N) users with normal cochlear anatomy. Speech perception in noise and sound localization skills were compared under 2 conditions; binaural (bilateral or bimodal) and monaural (first CI alone).

Results: BIM-IP and BIL-IP showed no performance difference in binaural tasks. The BIM-N group showed remarkably poor performance in comparison to the groups of BIL-IP (p = .007), BIM-IP (p < .001), and BIL-N (p = .004) in terms of speech-in-noise skills. In sound localization abilities, similar significant differences were found between the group of BIM-N and the groups of BIL-IP (p = .001), BIM-IP (p < .001), and BIL-N (p = .004). All groups showed statistically significant improvements in binaural condition on both tasks (p < .05).

Conclusion: We revealed that bilateral and bimodal pediatric CI users with IP-II benefitted from implantation as much as bilateral users with normal anatomy. Differences in residual hearing between groups may explain the poor performance of bimodal users with normal cochlear morphology. To the best of our knowledge, it is the first study to unveil binaural performance characteristics in children diagnosed with a specific inner ear malformation subgroup.