Objective: We aimed to determine whether long-term cortical auditory development is altered or delayed in children using cochlear implants relative to their normal hearing peers. We hypothesized that cortical development in children using unilateral cochlear implants follows a normal trajectory with long-term auditory input when the duration of bilateral auditory deprivation in childhood is limited.
Methods: Electrically-evoked cortical responses were recorded in 79 children who received one cochlear implant within 2.03 ± 1.36 years of bilateral deafness and had up to ∼16 years of time-in-sound experience, and in 58 peers with normal hearing. Amplitude differences between the responses from children using cochlear implants and with normal hearing were calculated between 0 and 300 ms.
Results: Responses from cochlear implant users remain different from those of their normal hearing peers. These differences decreased over time, but were not eliminated even after 10 years of time-in-sound. Specifically, the P(1)-N(1)-P(2)-N(2) complex, typical of a normally mature response, began to emerge by 10 years of time-in-sound experience, but the amplitudes of peaks P(2) and N(2) became abnormally large.
Conclusion: Mature-like cortical responses emerge in children after long-term unilateral cochlear implant use, however, differences from normal persist.
Significance: Maturation of cortical responses with long-term cochlear implant use potentially underlies functional improvements in hearing. Persistent differences from normal could reflect an increase in attention or multi-sensory processing during listening.
Keywords: Auditory cortex/brain; Child/adolescent; Cochlear implant/electrical stimulation; Deafness/hearing loss; Electrophysiology/auditory evoked potential; Long-term development.
Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.