Cochlear implants - SHHH position paper

Steve Hoffman steve at accessone.com
Tue Apr 9 16:46:22 EST 1996


Self Help for Hard of Hearing People

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 benefited 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implants have been superseded by multi-channel devices which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 prelingual 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
  o 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.

  o 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.

  o 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

  o 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 prelingual hearing losses.

  o 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.

  o 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.

  o 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.

  o 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.

  o 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.

 JOIN US IN MAKING HEARING LOSS AN ISSUE OF NATIONAL CONCERN

 Self Help for Hard of Hearing People, Inc.
 7910 Woodmont Ave - Suite 1200
 Bethesda, Maryland 20814
 301-657-2248 Voice
 301-657-2249 TTY
 301-913-9413 Fax



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