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

We examined the impact of residual hearing prior to cochlear implantation on pre- and postimplantation speech perception outcomes in children. Stimulation of the auditory system prior to implantation because of the presence of residual hearing is important for development of the central auditory pathways, 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, we identified 37 children who had an audiometric pure-tone average of better than 95 dB HL in the better ear at any time preimplantation. Psychophysical speech perception measures, the Word Identification Picture Inventory and the Phonetically Balanced Kindergarten list, in these children were compared with those of 96 implanted children who had poorer hearing prior to implantation. Children with more residual hearing showed higher speech perception scores both before implantation and over their first year of implant use than children with poorer hearing, suggesting that there is an advantage in having a greater degree of residual hearing preimplantation. We suggest that this advantage is promoted, in part, by the greater potential for auditory stimulation provided by high-gain hearing aids in children with greater degrees of residual hearing. This advantage appears to be maintained at least over 1 year postimplantation, yet the rates of development of postimplantation 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 the delay of speech perception skills in the preimplantation phase, particularly in children with poor residual hearing. This can be accomplished by implanting children with congenital severe to profound hearing loss at young ages and children with acquired hearing loss soon after the onset. Also, auditory stimulation prior to implantation should be maximized through the consistent use of hearing aids and therapy that emphasizes development of auditory skills.

The role of a graded profile analysis in determining candidacy and outcome for cochlear implantation in children.

Assessment of candidacy for cochlear implantation in children continues to present a challenge to cochlear implant programs. The efficacy of implantation depends on a number of factors and as a result a multidisciplinary approach has been adopted. At the Cochlear Implant Program at The Hospital for Sick Children, Toronto, we use a graded profile analysis (GPA) which has been adapted from the Children's Implant Profile (CHIP) developed by Hellman (S.A. Hellman, P.M. Chute, R.E. Kretschmer, M.E., Nevins, S.C. Parisier, L.C. Thurston, The development of a Children's Implant Profile, Am. Ann. Deaf. 136 (1991) 77-81). This structured assessment allows each potential candidate to be 'scored' in each category of assessment giving a potential range of -14 to +14. In this retrospective study of 109 candidates we examine the relationship between GPA scores and decision to implant. For those patients who were implanted, the relationship between GPA score and speech perception outcomes was also evaluated. Three distinct groups of children emerged from the analysis. The first group had scores less than 5 and were not considered to be suitable for implantation. Within the second group who scored between 5 and 8, there was no clear relationship between decision to implant and score. The last group, who scored 9-14, was considered to be generally suitable for implantation provided that there were no medical contraindications and the parents consented to implantation. There was a significant association between rate of improvement of speech perception and GPA score. Those patients with scores of 9 to +14 improved at a faster rate than group 5-8 (P < 0.05). The implications of these findings are discussed.