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 cross-modal 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. Overall, our results suggest that CI in pediatric SSD patients may benefit from a highly plastic cortex in childhood.