Cortical plasticity and reorganization in pediatric single-sided deafness pre- and postcochlear implantation a case study

Hypothesis: The purpose of this study was to examine changes in cortical development and neuroplasticity in a child with single-sided deafness (SSD) before and after cochlear implantation (CI). Background: The extent to which sensory pathways reorganize in childhood SSD is not well understood and there is currently little evidence demonstrating the efficacy of CI in children with SSD. Methods: High-density 128-channel electroencephalography (EEG) was used to collect cortical auditory evoked potentials (CAEP), cortical visual evoked potentials (CVEP), and cortical somatosensory evoked potentials (CSSEP) in a child with SSD, pre-CI and at subsequent sessions until approximately 3 years post-CI in her right ear which occurred at age 9.86 years. Behavioral correlates of speech perception and sound localization were also measured. Results: Pre-CI, high-density EEG showed evidence of delayed auditory cortical response morphology, auditory cortical development strongly contralateral (to the normal hearing ear), evidence of increased cognitive load, and crossmodal reorganization by the visual and somatosensory modalities. The post-CI developmental trajectory provided clear evidence of age-appropriate development of auditory cortical responses, and decreased cross-modal reorganization, consistent with improved speech perception and sound localization. Conclusion: Post-CI, the child demonstrated age-appropriate auditory cortical development and improved speech perception and sound localization suggestive of significant benefits from cochlear implantation. Reversal of somatosensory recruitment was clearly apparent, and only a residual amount of visual cross-modal plasticity remained postimplantation.