ERIC Identifier: ED414672
Publication Date: 1997-08-00
Author: Laughton, Joan
Source: ERIC Clearinghouse on
Disabilities and Gifted Education Reston VA.
Educating Children Who Are Deaf or Hard of Hearing: Cochlear
Implants. ERIC Digest #E554.
A cochlear implant prosthesis is a device that includes an external package
(microphone and speech processor) worn by the user and an internal package (an
array of electrodes that is surgically implanted into the cochlea (end organ of
hearing) in the inner ear. The internal and external components of the cochlear
implant are connected via an electric coupling. Cochlear implant prostheses are
designed to create hearing sensation by direct electrical stimulation of
auditory neurons (nerves). Several designs of this prosthesis have been used
although they have similar basic components. The speech processor is worn
externally and converts characteristics of sound signals (acoustic parameters)
into electrical characteristics (parameters). The purpose of the device is to
improve speech recognition of cochlear implant users by representing acoustic
(sound) information. The original single-channel implants have been replaced by
greater use of multichannel implants, where the stimulation is distributed
across an array of electrodes that evoke a wider range of auditory perception.
Cochlear implants are options for habilitation (i.e., helping a person
develop or learn new skills or abilities) or rehabilitation (i.e., helping a
person relearn old skills that were lost somehow) available for individuals with
profound hearing impairment (Geers & Moog, 1994). After long-term use with
adults, a major research effort was undertaken to evaluate effectiveness for
children. In 1990 cochlear implants were approved by the United States Food and
Drug Administration for children between the ages of 2 and 17. Considerable
research has been directed toward the effectiveness of these devices. Most early
research focused on the benefit gained from use of cochlear implants in
conjunction with speechreading (Geers & Moog, 1992). More recent research
has investigated the receptive and expressive language gains experienced by
users of cochlear implants (Hasenstab & Tobey, 1991). Early studies of
children showed that they followed a pattern similar to adults in that most
users had post-lingual hearing losses (i.e., after the age of five). More
recently, benefits to pre-lingually hearing impaired (i.e., before the age of
two) children have been observed. Research shows that pediatric implant users
gain substantial benefit from multichannel cochlear implants, that these
benefits develop over a long course of time, and that multichannel implants are
more beneficial than single-channel devices (Hasenstab, 1989).
Who can use this technology?
Candidacy requirements for receiving a cochlear implant are changing. Before
the FDA approved implants, children with profound deafness who were at least two
years old, and who received no benefit from conventional hearing aids, were the
primary recipients. Several significant factors interact in the consideration of
cochlear implants as an option. Age of onset of deafness is an important factor,
specifically whether the deafness was prelingual or postlingual. Etiology or
cause of hearing loss is significant as well. The majority of children with
postlingual deafness have meningitis as the cause of deafness. These children
are also at risk for additional outcomes such as neurological dysfunction or
cochlear ossification (hardening of the bone), presenting surgical challenge.
The majority of children receiving implants are prelingually deaf and may be
completely unfamiliar with sound.
Trends in effective use of cochlear implants have been observed. The
postimplant performance of children with acquired or congenital deafness before
age three show speech perception results that are similar. The postimplant
performance of children with postlingual deafness is better on most outcome
measures, but those differences become smaller over time. Performance is better
for children who are implanted when younger than age four. The research has
shown large within-group differences on all measures that suggest that some
factor(s) other than age of onset affect postimplant performance differences.
The traditional candidacy criteria have been:
- Age 2 or older
- Profound deafness
- Consistent pattern of hearing aid use
- Intensive auditory training
- Hearing levels greater than 100 dB.
The traditional candidacy criteria have included only those children who have
demonstrated no benefit from conventional amplification. Intensive auditory
training should include training in detection of sounds as well as recognition
of closed sets of spoken works. In a closed set, candidates are given options of
words to choose from; in an open set they must decide on a word without any
clues. More recent changes in candidacy criteria are leaning toward relaxing
that criterion. The performance of children with some residual hearing has
resulted in a recommendation to include them in the selection group. Comparative
studies of children with cochlear implants and with conventional hearing aids
have shown rapid gains (within six months) of the cochlear implant users
(Hasenstab & Tobey, 1991). Further research detailing changes with respect
to duration of implant use, significance of age of onset of deafness, and age of
implantation is needed.
What are the benefits of cochlear implants?
With adults the benefits of cochlear implants have ranged from communication
by hearing alone with ease (with or without speechreading) to the recognition of
sounds not available prior to the implant. Some adults can recognize sounds in
an open set with hearing alone. Adult cochlear implant users are primarily
individuals who have learned language and then lost their hearing. The purpose
of cochlear implants for children is to enable them to develop spoken language.
The benefits of implants that have been shown in research include increased
capacity for spoken language acquisition. This has been observed as children
move from no recognition to substantial open set recognition within six months
as contrasted to much longer times required for hearing aid users to attain this
level of performance.
Some observers feel that successful implant use is related to age of onset of
deafness and implantation, etiology (cause of deafness), type of prior language
habilitation program (spoken or sign language), parent involvement, and
cognitive and language development. The enhanced information about sound that is
available to the user is one of the major benefits of implants when contrasted
to conventional hearing aids. When implanted early after the onset of a loss,
the enhanced perception of sound may be expected to provide the child with the
information required for spoken language acquisition. Parents have reported
rapid behavioral improvement postimplant. Both parents and teachers have
reported significant receptive language improvement in phonologic (speech
sounds) and semantic (word meaning) domains. Increased intelligibility of speech
has also been reported. Cochlear implants are highly reliable but must be
accompanied by an intensive auditory rehabilitation component for successful
What are the limitations of cochlear implants?
Little is currently known about the long-term effect of the cochlear implant.
Implants require surgery. Although post-surgical complications have been quite
low, there are risks of infection with surgical procedures. Although rare, the
possibility of scalp flap complications and migration (movement) of the
electrode array from the scala tympani (area in the inner ear) are present. The
expense of the medical, audiological, rehabilitation, and educational components
of surgical implantation is significant. Although uncommon, certain conditions
may require re-implantation of the device.
are some questions to ask in choosing this option?
can I find out more about cochlear implants?
type of communication development or rehabilitation program has my child
received to date?
I have a philosophical commitment to spoken language development for my child?
is the optimal time for my child to receive an implant?
ear will be implanted? Why?
are the surgical procedures and risks?
will I deal with after-hours emergencies or concerns?
will the rehabilitation plan be developed and implemented?
is the long-term projection in terms of device replacement and cost?
I willing to commit the time, energy, and dedication required to make the use of
a cochlear implant a success?
my child's school ready and able to work with him as an implant user?
American Speech and Hearing Association. (1986).
Report of the Ad Hoc Committee on Cochlear Implants. ASHA, 28-51.
Geers, A., & Moog, J. (1994). The effectiveness of cochlear implants and
tactile aids for deaf children. A report of the CID sensory aids study. Volta
Review, 96(5), 1-232.
Geers, A., & Moog, J. (1992). Speech perception and production skills of
students with impaired hearing from oral and total communication education
settings. Journal of Speech & Hearing Research, 35 (1), 384-93.
Hasenstab, S. (1989). The multichannel cochlear implant in children. Topics
in Language Disorders, 9(4), 45-58.
Hasenstab, S., & Tobey, E. (1991). Language development in children
receiving Nucleus multichannel cochlear implants. Ear and Hearing, 12(4),
Miyamoto, R., Osberger, M., Robbins, A., Myers, W., Kessler, K.(1993).
Prelingually deafened children's performance with the Nucleus multichannel
cochlear implant. American Journal of Otology, 15, 9-14.
National Institutes of Health (NIH). Cochlear Implants in Adults and
Children. 100th NIH Consensus Development Conference. Bethesda, MD, May 1995.
Nevins, M. & Chute, P. (1995). Children with cochlear implants in
educational settings. Washington, DC: A.G. Bell Assn. for the Deaf.
Staller, S., Dowell, R., Beiter, A. (1991). Perceptual abilities of children
with the Nucleus 22 channel cochlear implant. Ear & Hearing, 12(4), 34S-47S.
Tobey, E. (1993). Speech production. In R.S. Tyler (Ed.) Cochlear implants:
Audiological foundations. San Diego, CA: Singular Publishing Group.
A.G. Bell Association for the Deaf, 3417 Volta Place, NW, Washington, DC
American Speech-Language-Hearing Association (ASHA), 10801 Rockville Pike,
Rockville, MD 20852.
Cochlear Implant Club International, 2000 Church Street, Box 111 Nashville,
Division for Children's Communication Development, The Council for
Exceptional Children, 1920 Association Dr., Reston, VA 20191.
National Institute on Deafness and Other Communication Disorders, 9000
Rockville Pike, Bethesda, MD 20892.
Network of Educators of Children with Cochlear Implants, Manhattan Eye, Ear
& Throat Hospital, 210 East 64th St., New York, NY 10021.