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Updated: Jul 11, 2026
Systematic Hearing Performance Evaluation Process for Adolescents with Cochlear Implantation at Early Ages
Published on: March 24, 2023
Auditory brainstem activity in children with 9-30 months of bilateral cochlear implant use
K A Gordon1, J Valero, B C Papsin
1Cochlear Implant Laboratory, The Hospital for Sick Children, Room 6D08, 555 University Avenue, Toronto, ON, Canada M5G 1X8. karen.gordon@utoronto.ac
Insights
Bilateral cochlear implants can restore hearing, but prior unilateral use may impact auditory brainstem plasticity. Early implantation (<3 years) aids recovery, while later implantation with delays shows persistent differences.
Area of Science:
- Neuroscience
- Audiology
- Biomedical Engineering
Background:
- Bilateral cochlear implants (CIs) are crucial for restoring binaural hearing in children with bilateral deafness.
- Auditory brainstem pathways are key to processing sound and developing auditory skills.
Purpose of the Study:
- To assess auditory brainstem activity following bilateral cochlear implant use.
- To investigate the impact of unilateral implant use duration and age at implantation on auditory plasticity.
Main Methods:
- Auditory brainstem responses (ABRs) were measured using single pulses from apical/basal electrodes in 13 children with bilateral CIs.
- Repeated measures were taken over 9-30 months of bilateral CI use.
- Latency differences of Wave eV were analyzed based on prior unilateral CI experience and delay between implants.
Main Results:
- Initially prolonged Wave eV latency was observed in the non-implanted ear compared to the previously implanted ear.
- These latency differences resolved in children implanted before age 3 but persisted in older children with long delays.
- Simultaneous bilateral implantation showed no latency differences and decreased response latencies over time.
- Binaural interaction responses were influenced by electrode position and delay between implants.
Conclusions:
- Prolonged unilateral CI use before bilateral implantation may negatively affect auditory brainstem plasticity.
- Early bilateral CI intervention, especially before age 3, promotes better auditory pathway development.
- The timing and duration of CI use significantly influence the recovery of binaural processing.
Abstract:
Bilateral cochlear implants aim to restore binaural processing along the auditory pathways in children with bilateral deafness. We assessed auditory brainstem activity evoked by single biphasic pulses delivered by an apical or basal electrode from the left, right and both cochlear implants in 13 children. Repeated measures were made over the first 9-30 months of bilateral implant use. In children with short or long periods of unilateral implant use prior to the second implantation, Wave eV of the auditory brainstem response was initially prolonged when evoked by the naïve versus experienced side. These differences tended to resolve in children first implanted <3 years of age but not in children implanted at older ages with long delays between implants. Latency differences were projected to persist for longer periods in children with long delays between implants compared with children with short delays. No differences in right versus left evoked eV latency were found in 2 children receiving bilateral implants simultaneously and their response latencies decreased over time. Binaural interaction responses showed effects of stimulating electrode position (responses were more detectable when evoked by an apical than basal pair of implant electrodes), and duration of delay between implants (measured by latency delays). The trends shown here suggest a negative impact of unilateral implant use on bilateral auditory brainstem plasticity.