Sequential bilateral cochlear implantation: speech perception and localization pre- and post-second cochlear implantation

Abstract

Purpose: In this study, the authors sought to compare speech perception and localization in subjects who wear 1 cochlear implant (unilateral CI) or 1 cochlear implant and hearing aid (CI+HA) and then receive a second cochlear implant (bilateral CI), and to evaluate the importance of the duration between implant surgeries and duration of deafness.

Method: Nine subjects were tested on speech perception in quiet, and 13 subjects were tested on speech perception and localization in noise using an array of 8 loudspeakers. All subjects were tested with unilateral CI prior to bilateral implantation and then again with bilateral CI after at least 3 months of bilateral experience.

Results: No significant difference was found between bilateral CI and unilateral CI on averaged speech perception in quiet performance. A significant benefit was found for bilateral CI on averaged speech perception in noise and on localization. Nonsignificant correlations were found for duration between surgeries, duration of deafness, and duration of bilateral use.

Conclusions: Improvements for speech perception and localization played in background noise were indicated for most subjects after they received their 2nd implant. The correlations should be reassessed with a larger number of subjects to appropriately evaluate the effects of duration between surgeries, duration of deafness, and duration of bilateral use.

Figures

Figure 1

Nine individual and group average CNC word in quiet scores for unilateral CI and bilateral CI (a “+” next to the subject name denotes those who used a CI+HA). The single asterisk indicates a significant improvement in performance between unilateral CI and bilateral CI test conditions whereas the double asterisk indicates a significant decrement in performance between these two conditions.

Figure 2

Thirteen individual and group average Cueing-the-Listener signal-to-noise ratio for unilateral CI and bilateral CI (a “+” next to the subject name denotes those who used a CI+HA). Average scores are shown with standard error bars. The single asterisk indicates a significant improvement in performance between unilateral CI and bilateral CI test conditions whereas the double asterisk indicates a significant decrement in performance between these two conditions.

Figure 3

Thirteen individual and group average localization RMS-error in degree scores for unilateral CI and bilateral CI (a “+” next to the subject name denotes those who used a CI+HA). The solid line at 50 degrees indicates chance score and the two dashed lines indicate the 95% confidence interval for this chance score. The single asterisk indicates a significant improvement in performance between unilateral CI and bilateral CI test conditions.