Multiple effects of childhood deafness on cortical activity in children receiving bilateral cochlear implants simultaneously.

Abstract Objective Auditory development is disrupted without normal hearing but might proceed to some extent depending on the type and onset of deafness. We therefore hypothesized that activity in the auditory cortex would be highly variable in children who are deaf. Methods To answer this, activity in the deaf brain was evoked by electrical pulses from newly provided bilateral cochlear implants (CIs) in 72 children ( n =144 responses). Results Responses were categorized by visual inspection into 3 main types which were validated by principal component cluster analyses; 49% had a negative amplitude wave similar to that previously reported in pre-term infants, 26% were dominated by a positive peak typical of responses in young normal hearing children and experienced paediatric CI users, 25% were novel multi-peaked responses. No significant demographic differences, including duration and onset of deafness, were found between response types. However, children with severe biallelic mutations of GJB-2 showed predominately negative peak type responses (79%) as compared with their peers without these mutations who had a more equal distribution between cortical response types. Conclusion Cortical development in children who are deaf is heterogeneous but can be better predicted when the genotype is known to be a GJB-2 mutation. Significance Remediation of childhood deafness seeks to restore normal development and function of central auditory functions and thus may need to be tailored to account for effects specific to the aetiology of deafness.