Children in the United States first received a cochlear implant (CI) to restore aspects of their hearing almost 20 years ago. Since then, candidacy criteria changed as safety and effectiveness data evolved and functional communication measurements were developed (Clark, 2008). Cochlear implantation continues to be a viable treatment option for many children with severe-to-profound hearing loss. One indication of the widespread acceptance of CIs is found in Healthy People 2010, a national report that calls for an increase in the proportion of CI users (U.S. Department of Health and Human Services, 2000); the proposed 2020 document retains this goal.

Clinicians need to stay current with a number of issues associated with implanting children with CIs: communication outcomes, referral patterns associated with pediatric CI candidates, and the degree of certainty that a child is a candidate for implantation.

Studies of pediatric cochlear implantation results are influenced by participant characteristics, as determined by available technology (which continues to evolve and includes hybrid CIs, FM capabilities, and advanced speech-coding strategies), and eligibility criteria. The date of an implant offers valuable information based on the technology and eligibility criteria in place at that time and sets the stage for understanding the communication outcomes associated with pediatric cochlear implantation. Clinicians who understand these issues can evaluate the observed outcomes and provide a context for interpreting the influence of pediatric cochlear implant studies.

When CIs were introduced in the early 1980s, extremely conservative candidacy criteria (only adults older than 18 who had profound bilateral sensori-neural post-lingual deafness and who received no benefit from hearing aids) were established to maximize the safety of surgical techniques, associated hardware, and software signal-processing strategies. In 1990 the U.S. Food and Drug Administration (FDA) approved CIs for implantation in children 2 years and older with profound hearing loss who were unable to identify words and sentences presented in auditory-only conditions using conventional hearing aids (Bradham & Jones, 2008).

By 2000 the FDA lowered the eligibility age to 12 months and increased the threshold degree of residual hearing; this change allowed many children with severe-to-profound hearing loss who correctly identified 30%–40% of words or sentences presented in auditory-only conditions to access implant technology. Further evaluation of the age of implantation continues as investigators around the world attempt to establish if earlier implantation age—less than 12 months—provides equivalent or superior outcomes relative to implantation at older ages.

Communication Outcomes

The Dallas Cochlear Implant Program is involved in several studies examining performance outcomes in pediatric cochlear implantation. One of the major studies is led by Ann Geers and colleagues from the University of Texas at Dallas, University of Texas Southwestern Medical Center, Indiana State University, the University of Colorado at Boulder, Washington University Medical Center, and the Moog Center for Deaf Education. Geers, in one of the largest cohort investigations of children using CIs in the northern hemisphere, is studying 181 American and Canadian children to document the characteristics of the children, their families, and their educational environments (Geers & Brenner, 2003). The children, 8 to 9 years old, all received their CIs between the ages of 2 and 5 years. Prior to implantation the children demonstrated profound, bilateral hearing loss with no ability to understand speech presented in auditory-only conditions. Educational environment data included classroom placement, communication mode used, and individual intervention. Family factors included socioeconomic status, family size, education level of mother, and parental involvement in educational programs. Data on the children included age of first identification for hearing aids, pre-implant residual hearing, duration of implant use, and presence of multiple disabilities.

Geers reported that more than 50% of the children scored within the average range for their ages on standardized reading measures (Geers, 2003). Moreover, levels of reading were associated with higher nonverbal intelligence, higher family socioeconomic status, female gender, and late onset of deafness. After accounting for these factors, reading proficiency was associated with mainstream educational placement, use of updated CI technology, and cognitive processing skills such as longer memory spans. Reading proficiency was highly predicted by level of language competence and speech production skills (Geers, 2006).

In a similar study, Tobey and colleagues found speech intelligibility for key words in the group averaged 63.5% with relatively few communication breakdowns (Tobey et al., 2003). Predictors of speech intelligibility were related to nonverbal intelligence, gender, family size, speech processing strategies, and participation in classrooms that emphasized speech and listening. Higher performance was found in children who were female, from small families, used current implant technology, and demonstrated high intelligence quotients. Geers and colleagues are completing a follow-up to their study, designed to re-evaluate the children—now adolescents—to assess the impact of cochlear implantation on literacy development. Preliminary data are encouraging—children with CIs continue to refine communication skills through adolescence on many measures.

Although additional analyses of the data from the Geers study of 8- and 9-year-old children with CIs failed to document a performance advantage based on age of implantation, several other studies are noting earlier implantation may be associated with higher communication performance in children using CIs (Lesinski-Schiedat et al., 2004; Schauwers et al., 2008; Tait et al., 2007a; Vlastarakos et al., 2010). Spoken language skills were measured recently in a large sample of 5- and 6-year-old children using CIs (N=153) who were enrolled in 39 oral communication programs in the United States (Geers et al., 2009). Age-appropriate performance was observed in 47% of the children for receptive language and in 39% of the children for expressive language. Approximately 50%of the children achieved age-appropriate performance on measures of receptive and expressive vocabulary. Higher scores on all language measures were observed for children with younger ages of implantation after accounting for nonverbal intelligence quotients and parental education.

Similarly, higher spoken-language performance in children with early implantation was found in a study examining 76 children at age 3.5 years who had at least seven months of experience with a CI (Nicholas & Geers, 2006). Almost 60% of the variance in language performance in the children was accounted for by the pre-implant pure tone thresholds and the duration of CI use. Children with poorer hearing before implantation demonstrated lower language skills at 3.5 years. Children with earlier ages of implantation performed higher on language measures than children with later ages of implantation.

Nicholas and Geers asked an important follow-up question: Will children who receive cochlear implants at young ages catch up with their hearing peers? (Nicholas & Geers, 2007). Comparisons between the language samples acquired at 3.5 and 4.5 years revealed children implanted between 12 and 16 months were more likely to achieve age-appropriate language performance at 4.5 years than children implanted after 24 months of age. Children diagnosed and using hearing aids at the earliest ages experienced longer periods of hearing aid use before implantation. Children with greater aided residual hearing also experienced longer hearing aid trials before implantation. These data suggest long periods of hearing aid use prior to cochlear implantation may not always be the most beneficial course of action for young children who may be CI candidates.

A systematic cohort meta-analysis sought to evaluate the literature base dealing with communication performance in children implanted at younger than 2 years (Vlastarakos et al., 2010). Comparisons of data reviewed in three published articles indicated higher receptive, expressive, and open-set speech recognition in children implanted at younger than 1 year relative to children implanted between 1 and 2 yearsof age (Dettman et al.,2007; Holt & Svirsky, 2008; Lesinski-Schiedat et al., 2004).

Case studies also demonstrated increased vocal autonomy, babbling, and speech perception performance in children implanted at less than 1 year of age (Colletti, 2009; Tait et al., 2007b; Valencia et al., 2008; Waltzman & Roland, Jr., 2005). Collectively, these data provide an ever-increasing strong case for providing cochlear implantation as an option for children younger than 1 year of age.

Candidacy Referral and Guidelines

One consequence of rapid technological advances in cochlear implantation is the expansion of candidacy criteria. Most CI centers in the United States employ multidisciplinary teams to evaluate and counsel families regarding the appropriateness of a child for an implant. However, as implant teams gain experience and the dissemination of performance outcomes becomes more widespread, it is possible that different teams serving different populations across the country may interpret or develop slightly different criteria to meet their community's needs.

For example, Wiley and Meinzen-Derr completed a retrospective study of medical and audiological records of children in Cincinnati referred and not referred for CI candidacy evaluations from 2003 to 2005 (Wiley & Meinzen-Derr, 2009). Two audiologists who together had almost 20 years of CI experience and two audiologists with a combination of nearly 20 years of pediatric experience (but limited CI experience) evaluated 4-frequency pure tone averages, speech reception, or speech awareness thresholds. They were asked to examine the information and sort the children into three categories—definite candidates, borderline candidates, and definitely not candidates for cochlear implantation.

The study operationally defined the "gold standard" to be decisions made by audiologists with CI experience—thus, it compared decisions made by the audiologists with CI experience with the decisions made by audiologists with general pediatric experience. Agreement between the audiologists with and without CI experience was only fair (Kappa =.45, 95% confidence level=.35, p<.0001); and, somewhat surprisingly, agreement among the audiologists with CI experience also was only fair (Kappa =.45, 95% confidence level=.15, p<.0001).

The largest disagreements among all of the audiologists occurred in borderline candidates. Of the cases designated as "borderline" by audiologists without CI experience, the audiologists experienced with CIs rated 26% as "definite" candidates and 21% as "definitely not" candidates. Definite candidates demonstrated audiometric thresholds of 90 dB HL or higher, bilaterally with limited open-set capabilities; borderline candidates demonstrated greater degrees of residual hearing.

Further evaluation of the data revealed a child was more likely to be referred as a CI candidate if the child had parents who were married, lived in an area in which the average income was at or above the U.S. average, and was clinically managed by an otolaryngologist with a focus on otology rather than an otolaryngologist with broader interests. The data suggest clinicians may take marital status as an unconscious measure of family stability and ability to follow through on the extensive mapping, programming, and habilitation associated with post-implantation care.

Recently, the prevalence of severe-to-profound hearing loss in the United States was examined as a way of estimating how many children may be served with interventions such as CIs (Bradham & Jones, 2008). The Gallaudet Research Institute analyzed data from the 2000 census and the National Hearing Interview Survey to estimate the number of children in the United States ages 1–6 years who met audiological candidacy criteria in 2000. Estimates of the numbers of appropriate candidates ranged from 1,886 for 2-year-olds to 3,194 for 6-year-olds. Comparisons to the number of children actually implanted during 2000 revealed only 55% of the possible candidates had been implanted.

Several factors appear to influence the decision-making process involved in a child's CI candidacy, including the family's preferences, the child's cognitive and neurological status, and the amount of the child's residual hearing. Researchers in Canada, for example, found clinicians expressed concerns about whether children with hearing loss ranging from 70 to 90 dB HL were appropriate candidates for cochlear implantation (Fitzpatrick et al., 2009). Clinicians were more likely to rely on additional information for these borderline cases, including the child's spoken language, progress in treatment, social functioning, academic functioning, and classroom comprehension.

A prospective case series in Canada also examined how parents and clinical centers decide on candidates for simultaneous bilateral implantation (Ramsden et al., 2009). More than 60% of the children referred were considered unsuitable candidates for the procedure because of developmental delays, residual borderline hearing in one ear, poor prognosis for speech development, and family refusal to consider the bilateral procedures (based on concerns about the appearance of wearing two CIs, not wanting to surrender the use of hearing aids, and wanting to preserve one ear for future technological advances).

As the landscape for CI eligibility continues to evolve, clinicians will want to stay current on technology and eligibility criteria to help families find the most appropriate intervention for their child and family. Evidence continues to accumulate on establishing the timing of implantation, implanting children with greater amounts of residual hearing, and reducing the length of hearing aid trial to assure early implantation. Future studies will need to be designed carefully to provide the data needed to assist clinicians in helping families make critical decisions for their children.