Richard T Miyamoto Karen Iler Kirk and Laurie S Eisenberg

CHAPTER 80

In 1990, the Food and Drug Administration (FDA) first gave approval for cochlear implantation in children aged 2 to 18 years. Initially, children who received a cochlear implant (CI) had total profound deafness, and most were older than 5 years of age. Early speech perception results demonstrated that congenitally or prelin-gually deafened children with a CI displayed substantial closed-set abilities (e.g., wherein children identify a word by selecting from a limited set of response alternatives), but only minimal open-set spoken word recognition abilities (i.e., in which no response alternatives are provided).1'2 Since then, as cochlear implantation has been extended clinically to younger children, and with continued improvements in electrode design and signal processing,3-6 pedi-atric CI recipients have achieved much higher levels of open-set word recognition.7-13 For example, Eisenberg and colleagues14 reported mean Phonetically Balanced Kindergarten word lists (PB-K) scores of approximately 50% words correct for oral pediatric CI users. Open-set word recognition is an important diagnostic yardstick for determining cochlear implant success because it indicates that these children have established neural representations of words in their long-term lexical memory, a process that is fundamental to the development of spoken language.15 Although these average results are very encouraging and clearly establish the efficacy of CIs, individual patients vary greatly in outcome.1-3,13,16-21 Some children can communicate extremely well using the auditory/oral modality and acquire age-appropriate language skills, whereas other children display only minimal spoken word recognition skills or demonstrate severe language delays, or both.22-27 Accounting for this enormous variability in the effectiveness of CIs on a wide range of outcome measures presents the most serious challenge facing cochlear implant clinicians and researchers today. Gaining an understanding of the nature of the individual differences and sources of variability in cochlear implant outcomes is crucial for predicting individual benefits before implantation and for selecting appropriate intervention strategies after implantation.

Despite the variability in individual outcomes, cochlear implantation is no longer questioned as a therapeutic option for children with prelingual deafness. However, in part because the outcomes are not guaranteed, controversy exists regarding the appropriate expansion of evolving technology into new patient populations. The current trend toward earlier implantation and the implantation of children with more residual hearing mandates careful documentation of performance limits with cochlear implants as well as with nonsurgical alternatives (e.g., hearing

* This work was supported in part by research grants 2 RO1 DC 00064, RO1 DC00423, and K08 DC00126 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health, and by Psi Iota Xi.

aids). Only through rigorous longitudinal studies will these issues be clarified. This chapter reviews current implant technology, patient selection criteria, and performance results for pediatric cochlear implant recipients and considers the challenges inherent in the broadening of cochlear implant candidacy.

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