Effect of residual hearing prior to cochlear implantation on speech perception in children

We examined the impact of residual hearing prior to cochlear implantation o n pre- and postimplantation speech perception outcomes in children. Stimula tion of the auditory system prior to implantation because of the presence o f residual hearing is important for development of the central auditory pat hways, whereas, in the absence of such stimulation, the pathways show less development. We hypothesized that children who had some degree of residual hearing preimplantation achieve better speech perception skills than their peers with poorer hearing. From the 133 children followed in our program, w e identified 37 children who had an audiometric pure-tone average of better than 95 dB HL in the better car at any time preimplantation. Psychophysica l speech perception measures, the Word Identification Picture Inventory and the Phonetically Balanced Kindergarten list, in these children were compar ed with those of 96 implanted children who had poorer hearing prior to impl antation. Children with more residual hearing showed higher speech percepti on scores both before implantation and over their first year of implant use than children with poorer hearing, suggesting that there is an advantage i n having a greater degree of residual hearing preimplantation. We suggest t hat this advantage is promoted, in part, by the greater potential for audit ory stimulation provided by high-gain hearing aids in children with greater degrees of residual hearing. This advantage appears to be maintained at le ast over I year postimplantation, yet the rates of development of postimpla ntation speech perception are not different between the groups. We suggest that this may be due to the unique aspects of electrical stimulation from a cochlear implant. Our findings suggest that it is important to minimize th e delay of speech perception skills in the preimplantation phase, particula rly in children with poor residual hearing. This can be accomplished by imp lanting children with congenital severe to profound hearing loss at young a ges and children with acquired hearing loss soon after the onset. Also, aud itory stimulation prior to implantation should be maximized through the con sistent use of hearing aids and therapy that emphasizes development of audi tory skills.