Impact of age at the second implantation, experience of amplification use, and long-term binaural experience on sound localization of children with bilateral cochlear implants.

Objectives: To assess the influence of three factors using retrospective chart review: age at which 2nd cochlear implant (CI) is implanted, prior hearing aid (HA) experience in the 2nd CI ear, and long-term experience with bilateral cochlear implants (BICIs) on sound localization in children with sequential BICIs.

Methods: Mean absolute error (MAE) in localizing speech noise of 60 children with sequential BICIs was compared across four age groups of the 2nd CI (1-5.0; 5.1-10.0; 10.1-14.0; & 14.1-19.0 years) and two extents of prior HA experience (more than and less than one year). MAE was also longitudinally analyzed after 4-6 years of experience with BICI involving 18 participants out of 60.

Results: Children who received 2nd CI before five years of age demonstrated significantly better localization than those who received it after ten years of age. More than one year of prior HA experience in the 2nd CI ear and extensive experience with sequential BICIs significantly enhanced localization performance. Inter-implant intervals and age at the 2nd CI showed a significant positive correlation with the MAE (poorer localization).

Conclusion: The results indicate that age at 2nd CI is important in developing sound localization skills. Based on the results, obtaining 2nd CI within the first five years of life and no later than ten years old is recommended. The results also suggest that longer use of amplification before 2nd CI and prolonged BICI experience significantly fosters localization development.