The Extent of Hearing Input Affects the Plasticity of the Auditory Cortex in Children With Hearing Loss: A Preliminary Study.

Purpose: This study investigated to what extent residual hearing and rehabilitation options (e.g., hearing aids [HAs]) affect the auditory cortex in children with hearing loss.

Method: Twenty-one children with bilateral congenital sensorineural hearing loss who were candidates for cochlear implantation were recruited. Voxel-based morphometry analysis was conducted to assess the gray matter (GM) volume in the auditory cortex. Children's residual hearing was measured by pure-tone audiometry at different frequencies. Multiple linear regression models were conducted to examine the effects of residual hearing and the use of HAs on GM volume in the auditory cortex with the control of age and gender.

Results: Children with more residual hearing at high frequencies had larger GM volume ratio (corrected by total intracranial volume) in the left Heschl's gyrus ( = -.545, = .013). An interaction effect between residual hearing and the use of HAs suggested that the effect of residual hearing on GM ratio was moderated by the use of HAs (β = -.791, = .020). Compared with children with less residual hearing, children who had more residual hearing benefited more from longer use of HAs in terms of a larger GM ratio.

Conclusions: Our preliminary findings highlight the impact of residual hearing on the neuroanatomy of the auditory cortex in children with hearing loss. Moreover, our results call for more auditory input via HAs for children with more residual hearing to preserve the auditory cortex before cochlear implantation. For children with less residual hearing who might receive limited benefit from HAs, an early cochlear implant would be necessary.