Hearing benefits of second-side cochlear implantation in two groups of children

To investigate the additional bilateral benefits of a second cochlear implant (CI) in a group of young children (<6 years of age) and a group of older children (>6 years of age).

This is a Belgian tertiary multi-centre study in which 33 CI-children with a second implant between the age of 2 and 12 participated. Assessments took place pre-second implant and at several time intervals post-fitting on pure tone audiometry and speech recognition in quiet and noise (+10 dBSNR). Testing was done with the first and second implant alone and bilaterally. Results were analysed separately for children younger and older than 6 years at the time of implantation of the 2nd CI.

After 18 months of bilateral implant use all children obtained significantly higher hearing thresholds in the bilateral condition in comparison to both the unilateral conditions (p(CI1)=0.035/p(CI2)=0.042 for the younger children and p(CI1)=0.021/p(CI2)=0.007 for the older children). The speech recognition scores in quiet were for all children superior in the bilateral condition (p(CI2)=0.011 for the younger children and p(CI1)=0.016/p(CI2)=0.003 for the older children). In the noisy condition only significant bilateral better results were obtained in the group of younger children (p(CI1)=0.028/p(CI2)=0.034).

Bilateral cochlear implantation offers advantages to all children. Even for the children who received a second implant after the age of 6 a progress is determined after 18 months. However, the data appear to show a beneficial performance for those children who received their second implant before the age of 6, especially in the more challenging conditions.