The substantial benefit derived from cochlear implants by adults (see cochlear implants and cochlear implants in adults: candidacy) led to the application of these devices in children. Unlike adults, however, most pediatric candidates acquire their deafness before speech and language are learned (prelingually deafened). Thus, children must depend on an auditory prosthesis to learn the auditory code underlying spoken language—a formidable task, given the exquisite temporal and frequency-resolving powers of the normal ear. On the other hand, young children may be the most successful users of implantable auditory prostheses because of the plasticity of the central nervous system.

The challenges faced in determining candidacy in children require balancing the risks of surgery versus the potential benefits of early implantation for the acquisition of spoken language. Initially, the use of cochlear implants in children was highly controversial. Thus, candidacy requirements were stringent, and the first children to receive cochlear implants were older (school-age or adolescents) and demonstrated no benefit from conventional hearing aids—not even sound awareness—even after many years of use and rehabilitation. These children were considered “ideal” cochlear implant candidates because their hearing could be reliably evaluated and it was obvious that no improvement in their auditory skills would occur with conventional hearing aids.

The first devices used with children were single-channel implants (see cochlear implants). Even though performance was limited, the children who received these devices derived more benefit from their implants than from conventional hearing aids (Thielemeir et al., 1985; Robbins, Renshaw, and Berry, 1991). A small percentage of these children achieved remarkable levels of word recognition through listening alone, although many of them had early acquired deafness with some normal auditory experience prior to the onset of their hearing loss (Berliner et al., 1989). Benefits also were documented in speech production and language acquisition (Osberger, Robbins, Berry, et al., 1991). Clearly, the early pioneering work with single-channel devices demonstrated the safety and effectiveness of implantable auditory prostheses in children and paved the way for the acceptance of cochlear implants as a medical treatment for profound deafness.

Eventually children received multichannel cochlear implants, especially as results indicated superior outcomes with these devices compared with single-channel implants (Osberger, Robbins, Miyamoto, et al., 1991). Since that time, numerous research studies have documented the substantial benefits that children with profound hearing loss obtain from multichannel cochlear implants (see Kirk, 2000; Waltzman, 2000). Numerous speech perception tests have been developed to assess implant candidacy and benefit, even in very young children (Kirk, 2000; Zimmerman-Phillips, Robbins, and Osberger, 2000). A finding common to all studies is the long time course over which children acquire auditory, speech, and language skills, even with multichannel devices (Tyler et al., 2000) (Fig. 1). This is not unexpected, given the number of years required for similar skill acquisition by hard-of-hearing children who use conventional hearing aids.

Figure 1..  

Mean pre- and postimplant scores on phoneme recognition (Phonetically Balanced-Kindergarten test) achieved by children during Clarion cochlear implant clinical trials (mean age at implant = 5 years).

With continued clinical experience, improvements in technology, and documented benefits, cochlear implants gained greater acceptance, and candidacy criteria were expanded. Children received implants at increasingly younger ages, and it is now common practice to place implants in children as young as 2 years, with a growing trend for children as young as 12 months of age to receive cochlear implants (Waltzman and Cohen, 1998). Identification of hearing loss at an early age has also contributed to implantation in children at increasingly younger ages. Evidence suggests that children receiving implants at a younger age achieve higher levels of performance with their devices than children receiving implants at an older age (Fryauf-Bertschy et al., 1997; Waltzman and Cohen, 1998). Significant differences in postimplant outcome have been documented in children who receive implants before age 3 years. Children who received cochlear implants between ages 12 and 23 months demonstrated better auditory skills after implantation than children who received implants between the ages of 24 and 36 months (Fig. 2) (Osberger et al., 2002). Thus, a difference of as little as 1 year in age at the time of implantation had a significant impact on the rate of auditory skill development in these young children.

Figure 2..  

Mean pre- and postimplant performance on Infant-Toddler Meaningful Auditory Integration scale by age at implant (statistically significant difference between groups after 3 months of implant use).

Even though the current trend is to provide implants to children at younger ages, older children continue to receive cochlear implants (Osberger et al., 1998). Some of these children have residual hearing and demonstrate benefit from conventional hearing aids. Implantation is often delayed because it takes longer to determine whether a plateau in auditory development has been reached. In addition, the audiological candidacy criteria were more stringent when these children were younger, and thus they were not considered appropriate candidates because they had too much hearing. Over time, however, audiological criteria in children have been expanded for implants (Zwolan et al., 1997). Following implantation, children with preoperative speech perception abilities demonstrate remarkable auditory recognition skills and achieve higher levels of performance with their implants than they did with hearing aids (Fig. 3).

Figure 3..  

Mean pre- and postimplant performance on two open-set speech perception tests (Lexical Neighborhood and Multisyllabic Neighborhood tests) (recorded administration) and one closed-set test (Early Speech Perception Monosyllable Word test) (live-voice administration) (mean age at implant = 9 years).

Other factors besides age influence cochlear implant benefit in children. Communication method also impacts the postimplant performance in children. Most studies have found that children who use oral communication (audition, speaking, lipreading) achieve higher levels of performance with their implants than do children who are educated using total communication (English-based sign language with audition, speaking, lipreading) (Meyer et al., 1998). The trend for better implant performance in children who use oral communication has been shown in older children (Fig. 4) as well as in very young children (Osberger et al., 2002). This finding indicates that oral education programs more effectively emphasize the use of auditory information provided by an implant than do total communication programs. In fact, since multichannel cochlear implants became available, there has been a dramatic increase in the number of educational programs that employ oral communication, because a greater number of children have the potential to acquire spoken language through audition.

Figure 4..  

Mean pre- and postimplant performance by communication mode for older children (mean age at implant = 9 years) on the Early Speech Perception Monosyllable Word test) (live-voice administration) (statistically significant postimplant differences between groups).

In addition to auditory perceptual benefits, children with cochlear implants show significant improvement in their receptive and expressive language development (see Robbins, 2000). Improvements in the use of communication strategies and conversational skills have also been reported (Tait, 1993; Nicholas, 1994), and more children with implants demonstrate higher levels of reading achievement than reported for their peers with hearing aids (Spencer, Tomblin, and Gantz, 1999). Nonetheless, even with marked improvements in performance, children with cochlear implants remain delayed in linguistic development compared to children of the same chronological age with normal hearing. However, children with cochlear implants do not continue to fall farther behind in their language performance, as has been reported for their profoundly hearing-impaired peers with hearing aids. As deaf children receive implants at younger ages, the gap between their skills and the skills of their age-matched peers with normal hearing will lessen.

Speech production skills also improve after implantation. Studies have shown improved production of segmental and suprasegmental features of speech and overall speech intelligibility (Tobey, Geers, and Brenner, 1994; Robbins et al., 1995). Dramatic improvements in speech production are often apparent after only several months of implant use, even in very young children who had little or no auditory experience prior to implantation. In very young children, improvements in vocalizations are usually the most noticeable changes following implantation (Zimmerman-Phillips, Robbins, and Osberger, 2000).

Cochlear implants are now accepted as an effective treatment for profound deafness. Many profoundly deaf children gain access to the auditory and linguistic code of spoken language with these devices, an accomplishment realized by only a limited number of deaf children with hearing aids. Profoundly deaf children with cochlear implants often function as well as children with less severe hearing impairments with hearing aids (Boothroyd and Eran, 1994; Meyer et al., 1998). Consequently, deaf children with implants acquire spoken language vicariously through incidental learning, requiring fewer special support services in school. Evidence suggests that more deaf children who use implants are being mainstreamed in regular classrooms than their peers with hearing aids (Francis et al., 1999). Thus, the long-term educational costs for children with cochlear implants will be less than for deaf children with hearing aids, resulting in a net savings to society. In addition, cochlear implants have a positive effect on the quality of life of deaf children, and have also been found to be a cost-effective treatment for deafness (Cheng et al., 2000). Whereas the impact of cochlear implants on educational and vocational achievement will take many years to establish, it is clear that these devices have changed the lives of many deaf children and their families.