Position on Cochlear Implants

Background

In the last 25 years, cochlear implants have developed from a speculative laboratory procedure to an accepted clinical practice. The limited benefits possible with the initial generation of implants -- improvements in overall speechreading skills and auditorily "coupling" to a sound-producing environment -- were of sufficient value to these first subjects to warrant continued research on the device. Early studies proved that in the combined mode (implant plus vision), speechreading skills were superior to those obtained with vision alone. Except for several "stars" among the early cochlear implant recipients, however, the initial generation of implants could provide little or no open-set auditory recognition of speech.

Cochlear implants have benefitted from the remarkable advances occurring in recent years in microprocessors and miniature electronic circuitry. The primitive single channel cochlear implants have been superseded by multi-channel devices which provide access to a range of salient speech cues.

There is no doubt that they are here to stay. The major issues now concern the potential auditory and social implications of long-term implant use; the most suitable candidates; and, most importantly, who has the major responsibility for making the implant decision.

Insofar as adventitiously deafened adults are concerned, these questions are easy to answer. The rapidly accumulating body of research evidence shows that most such people receive some degree of benefit from an implant. This benefit varies from, at the lower limits, improved bi-sensory speechreading skills, to some auditory-alone speech recognition capability (achieved by over half the implant recipients). Once the possibilities, as well as the limitations of an implant are explained to them, these people have the capacity and authority to make their own decision regarding its desirability.

These questions are also relatively easy to answer for adults with congenital hearing losses. For the most part, these people have rarely had successful, or useful, experiences with traditional sound amplification. Generally, when someone in this population has tried an implant, the results have been much less favorable than for the adventitious group. However, as adults they, too, have the right and power to make their own decisions, based on a full and objective exposition of the possible consequences.

Children are a different matter; someone else must make the implant decision for them. Current surgical practice does not consider children as potential candidates until they reach two years of age. Based on the current research, the results with children can be broken down into two groups.

The first group of children are those who were born with normal hearing, but who developed a total or exceptionally profound hearing loss sometime after birth. The best candidates in this group are generally those who have had the longest period of normal hearing, as well as the shortest period from the onset of the hearing loss to the implantation. The results with these children indicate that the implant gives them immediate access to important speech features, which they can demonstrate by imitating most phonemes and combinations of phonemes through audition alone. Those whose hearing losses date from well into the lingual period have the capacity to respond to an implant in much the same fashion as do adventitiously deafened adults.

At this point, the children in this first group may diverge into two subgroups. Those who are given a sustained auditory language learning focus in their training continue to make auditory progress, eventually functioning like children with severe hearing losses who have received appropriate clinical/educational training. Their speech may exhibit some articulatory problems, but their voice quality is essentially normal. With training and experience, an increasing number are capable of comprehending speech through the auditory channel alone. In the second sub-group, those whose training program does not emphasize auditory learning continue to make auditory progress, but not at the same rate, nor do they reach the same level, as the children in the first sub-group. For all of these children (as for most children with hearing losses), the adequacy of the training program is a key factor in their overall educational progress.

The second group of children are those with pre-lingual and profound hearing losses. When implanted, these children do not display the same auditory responsiveness as the children in the first group. Lacking an auditory memory, the goal with these children is to help them develop auditory awareness, unlike the first group who simply need their previous auditory memory status re-stimulated. This second group of children must be taught to be aware of sounds in the environment, to "scan" for auditory events, and to listen and to imitate incoming speech sounds (the auditory-vocal monitoring system). Although progress is slower than in the first group, what research and clinical observations are making it increasingly evident is that, given an appropriate auditory language training program, auditory progress does continue. The most recent observations suggest that after several years of experience and training, this group of children may reach the same auditory developmental level as that of the first group. For children in both groups, receptive benefits continue to increase after 12-24 months of use, unlike the pattern seen in adults with adventitious hearing loss whose performance plateaus after this period.

Policy Recommendations

• A. General

  SHHH recognizes cochlear implants as a prosthetic device that can improve auditory skills. Future developments in health care technology may include other types of implants to more central auditory brain structures, or other, not yet even conceived, possibilities. Conceptually and functionally, the purpose is to improve access to auditory events. As with any prosthetic device, the employment of a cochlear implant depends upon the needs and status of the individual involved.

• B. Adults

  1. SHHH recommends that all adults with profound or total hearing loss, congenital or adventitious, be considered potential candidates for a cochlear implant. The hearing loss must be of sufficient magnitude to preclude the comprehension of speech through the auditory channel alone using conventional amplification devices. The decision whether an implant should be obtained depends, and must depend, upon the informed consent of the individual involved.

  2. The key provision is informed. Now that cochlear implants are an approved clinical procedure, it is possible that some surgical centers would now necessarily conduct the desirable preliminary studies (including neuro-otological, audiological, social, and psychological components) and follow-up studies routinely accomplished by major medical centers.

  3. SHHH recommends that persons contemplating a cochlear implant be evaluated and implanted in a center with demonstrable expertise. Factors to consider are the experience of the center, the nature of the preliminary evaluations, the frequency of the routine follow-up evaluations, and whether an aural rehabilitation program is recommended and conducted. When in doubt, persons contemplating a cochlear implant should avail themselves of a second opinion.

• C. Children

  1. No child should be considered a candidate unless he or she first receives an intense auditory language learning program utilizing more conventional technology (hearing aids, personal FM systems, vibro-tactile devices, or frequency transposers). There is currently no consensus regarding the length or composition of such a preliminary program, nor is there an agreement when the decision to implant should be made. As a general rule, the decision should be made as soon after an adventitious hearing loss has been sustained and as early in the child's life as possible for those with pre-lingual hearing losses.

  2. At the present time, children who can recognize speech through audition alone are not considered implant candidates. The actual degree of hearing loss (within the severe to total category) is less an indicator of candidacy than the functional use of residual hearing. Those children who effectively employ a bi-modal speech perception system may be suitable candidates.

  3. The final decision regarding a cochlear implant must be made by a child's parents. The responsibilities of the professional team involved in the implant process are to provide the parents with all the information they need to make such a decision. The full range of possible results must be explained, including explicit comments that the procedure does not replace the ear (as many parents think) or produce normal hearing. It is reasonable to use the average accomplishments of children who have been implanted to date as a legitimate prognostic marker.

  4. The capacity of a child to benefit from a cochlear implant is directly related to the adequacy of the subsequent educational program. Unless audition is intensively and continually stressed in the training program, it is unlikely that the full potential benefits of the implant can be realized. Therefore, post-implant auditory-based speech and language training should be seen as a critical component of the entire implant process.

  5. As yet, there is no information on the ultimate social and psychological consequences of implanting a young deaf child. We do not know how implantees will feel about the procedure when they are young adults, as they begin making their own decisions regarding their future. Judging from experiences to date with children with severe and profound hearing loss who use conventional amplification techniques, there will be no unanimity of responses. Some will resent the "imposition" of a prosthetic device upon them; others will bless their parents for making the decision. Most children will probably fall between these two extremes. When implanted children reach young adulthood, they have the capacity and authority to make their own decision regarding continued use of the implant, as well as the cultural and social milieu in which they feel most comfortable.

  6. With the acknowledgment that the ultimate authority for the implant decision rests with the parents, and subject to the qualifications expressed above, SHHH recommends that cochlear implants be considered as a viable option for deaf children.

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