Central auditory development after long-term cochlear implant use

Abstract

ObjectiveWe 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. MethodsElectrically-evoked cortical responses were recorded in 79 children who received one cochlear implant within 2.03±1.36years of bilateral deafness and had up to ∼16years 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 300ms. ResultsResponses from cochlear implant users remain different from those of their normal hearing peers. These differences decreased over time, but were not eliminated even after 10years of time-in-sound. Specifically, the P1–N1–P2–N2 complex, typical of a normally mature response, began to emerge by 10years of time-in-sound experience, but the amplitudes of peaks P2 and N2 became abnormally large. ConclusionMature-like cortical responses emerge in children after long-term unilateral cochlear implant use, however, differences from normal persist. SignificanceMaturation 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.