Beginning the Process
Once the decision is made to pursue a cochlear implant, there are
a variety of steps involved in the process. The first thing that
needs to happen is for the family to contact a hospital implant
center. To locate an implant center, check the cochlear implant
manufacturers:
For a discussion of issues to consider when selecting a cochlear
implant center, visit the Cochlear Implant Association Web site
at: http://www.cici.org/select.html.
What's Involved in the Process?
Most implant centers utilize a team approach to providing a comprehensive
assessment of a child's candidacy for cochlear implantation. The
process usually involves medical, audiological, speech and language,
education, and other support service professionals. Although each
hospital center may have its own protocol, the following components
of the process are typically included:
- Initial consult—Professionals from the hospital
implant center inform families of the cochlear implantation process.
Topics for discussion may include pre-implantation testing and
counseling, insurance coverage, the types of devices available,
the surgery, programming of the external components of the device,
and the training process.
- Audiological services—A current Auditory Brainstem
Response (ABR) evaluation is necessary to confirm the degree of
hearing loss. Behavioral testing should also be a part of the
test battery to provide a functional assessment of a child's hearing
level. For more information about understanding audiological evaluations,
see http://clerccenter2.gallaudet.edu/SupportServices/series/5002.html.
While a hearing aid trial is usually a part of the protocol,
the length of the trial period may vary depending on a variety
of factors. For example, a hearing aid trial may be short for
young children with confirmed profound hearing loss and limited
observable benefit from a hearing aid to hasten implantation
in the interest of the age of the child. A hearing aid trial
may be longer for an older child who has proven to be a poor
hearing aid user. An implant center may be trying to determine
if an older child demonstrates responsibility and motivation
to wear hearing aid technology.*
*Note: The rationale for an increased trial sometimes backfires
as a child with a profound loss may dislike and not be motivated
to use his or her hearing aid as he or she obtains limited benefit
from it. This same child may like a cochlear implant when he
or she has increased access to sound. Similarly, a parent who
is excited about obtaining a cochlear implant for the child
may not devote sufficient time and energy to a hearing aid trial.
The audiologist is the specialist who will program the external
components of the device, which will be activated about one
month following surgery after healing is complete. The modification
of the external speech-processing device specific to each user
is called "mapping."
- Speech-language, developmental, cognitive, and motor evaluations—These
evaluations provide information on a child's functioning in a
variety of areas. Some hospitals have on-site staff trained in
the specialized evaluation tools, techniques, and test standardizations
for deaf children. Some hospital programs collaborate with support
service professionals in school programs serving deaf and hard
of hearing children to obtain these evaluations. No matter where
the evaluations are completed, it is important that the professionals
completing them are trained in, and familiar with, the tools and
standards of evaluating deaf children.
- Rehabilitation consultation and training—Prior to
implantation, children and families may meet with a specialist
from the hospital center who is trained in facilitating listening
and speech skill development after implantation. Components of
the habilitation process are shared so family members have a clear
understanding of the training commitment that follows the surgery.
Oftentimes, children participate in the habilitation process prior
to surgery to get familiar with the activities and strategies
that will be used after implantation.
- Outreach with educational programs—Most children
and families in the implantation process are already enrolled
in a school or educational program. Collaboration between the
child's educational program and the hospital implant center can
facilitate the candidacy and habilitation process related to implantation.
The educational professionals may bring a perspective to the candidacy
process that may not otherwise be shared by the family or observed
in the hospital setting. This collaboration will also facilitate
development of appropriate educational goals and communication
strategies for the child when he or she returns to his or her
educational placement following implantation.
Choices During the Implantation
Process
Once the decision to implant has been made, there remain the choices
of which manufacturer to use and which ear to implant.
Choosing a Manufacturer
There are three manufacturers of cochlear implants commonly used
in the United States: Advanced
Bionics, Cochlear Corporation,
and MED-EL Corporation. For
more information about these manufacturers, visit their Web sites.
Some hospital implant centers offer the option of choosing an implant
from any of the three companies. Some hospital implant centers may
only offer one brand of cochlear implant. Some implant centers may
provide a preference for one manufacturer over another, while others
may not. Most centers will help families compare characteristics
of implants in order to make an appropriate choice. It may be helpful
to speak with other families regarding their experience with a particular
manufacturer as a decision is made.
Possible considerations in making this decision include:
- the casing of the internal component of the implant,
- the internal technology of the electrode positioners,
- the style of the external components of the implant,
- the speech-processing strategies offered by the manufacturer,
- the additional supports from the manufacturer (i.e., help obtaining
insurance, ease of ordering spare parts),
- the differences in battery life, and
- the considerations related to the need for possible Magnetic
Resonance Imaging Testing (MRI) in the future.
Deciding Which Ear to Implant
There are a variety of factors involved in making a decision about
which ear to implant, including:
- Anatomy of the ear system—CAT scans or MRIs, which
indicate the condition of the cochlea and the auditory nerve,
are utilized to determine the following impacting factors:
- Is there ossification (bony growth) of the cochlea? If so,
the insertion of the electrodes into the cochlea can be adversely
impacted. Presence of ossification does not mean that cochlear
implantation is not possible; however, the quality of sound
may be diminished if a sufficient number of electrodes cannot
be adequately inserted. If there is a difference in ossification
levels between ears, this may influence which ear is chosen
for implantation.
- Is the auditory (eighth) nerve intact? Though the implant
is placed within the cochlea, sound must be transmitted to
the brain via the eighth nerve. If this nerve is not intact
or is not present, the implant will not be possible in that
ear.
- Is the cochlea malformed? Though surgery may still be possible
with a malformed cochlea, the ear with a better-formed cochlea
is more likely to be chosen if all other factors are equal.
- If x-rays indicate that the facial nerve is too close to
the surgical area, this may impact the decision on which ear
to implant.
- Electrical stimulation—If one ear is noted to respond
better to the electrical stimulation of the cochlea as noted on
the Promontory Test, this may influence which ear to implant.
- Implantation of the better ear—If there is a difference
in hearing levels between ears, some centers may choose to implant
the better ear. This choice reasons that because the better ear
has been successful using a hearing aid, the auditory channels
in this ear have been accustomed to receiving stimulation and,
therefore, are ready to accept sound. Since this ear may already
possess some "skill" in processing spoken language,
this ear would more successfully acclimate and benefit from the
cochlear implant.
- Implantation of the worse ear—If there is a difference
in hearing levels between ears, some may choose to implant the
worse ear. This choice reasons that the "better" ear
could continue benefiting from a traditional hearing aid should
the cochlear implant not be successful.
- Pick the right ear—If there is no difference between
ears and everything else is equal, some centers may lean towards
implantation of the right ear. This choice reasons that since
the "speech centers" of the brain are on the left side
and there exists a crossover effect (sound transferred from the
right to the left side of the brain for processing), implantation
on the right side may facilitate processing of speech and language
information.
- Listening in the car—From a functional point of
view, adults may choose the right side to facilitate listening
to passengers in a car while driving. (This is really thinking
ahead for the 1-year-old implantee!)
Things to Ask the Cochlear Implant
Center
Below are brief responses to some frequently asked questions. These
issues can be discussed in further depth with a hospital implant
center.
What is the expected life of the device?
The manufacturers indicate that the internal components of the
devices are designed to last a lifetime. The external components
will face wear and tear issues similar to other hearing aids and
technological devices. As newer external devices evolve, a user
may need to update and/or replace the external components.
What about implanting both ears?
The use of two hearing aids improves sound localization, listening
in noise, and reduction of listening stress. This may also be the
case for cochlear implants. Bilateral implantation is being considered
and completed in increasing numbers of centers, but this practice
is still under investigation and not yet commonplace.
Questions to consider related to bilateral implantation include:
- Should the devices be mapped similarly in each ear?
- Can the sound from both sides be integrated and processed?
- Should one processor stimulate both ears?
- If both ears are implanted, will the person be a candidate for
future new technologies should they emerge?
For further information about bilateral implantation, see the MED-EL
Web site at: http://www.medel.com/ENG/INT/30_Advanced_topics/999_bilat.asp.
Will static electricity affect the cochlear implant?
Electrostatic discharge can cause damage to any electronic device,
however, implant manufacturers are improving the design of implants
to provide greater resistance to this problem. Clarion indicates
that their CII Bionic ear implant system is designed with special
safeguards for greater resistance to electrostatic discharge.
What is the risk of internal device failure?
While the risk of device failure is small, it is possible. In these
situations, additional surgery may be required to replace the device
or in some situations to reposition a device that has migrated from
its intended placement.
Can implanted children participate in sports?
Cochlear implantation should not interfere with most recreational
activities. Judgment should be utilized in determining if the external
portion of the implant should be used during sports. Of course,
the external processor should be removed for participation in water
sports. In addition, be aware that sweating and moisture can affect
the device. The surgically implanted portions of the implant will
not be damaged by water sports or diving into a swimming pool. The
only restriction that seems to be made by implant companies is related
to deep-sea scuba diving. This is based on severe pressure changes.
For sports that involve particular risk of head injury, common sense
indicates that head protection be utilized. Clinics usually advise
avoidance of activities like boxing, where a severe blow to the
head is likely.
What about waiting for the technology to improve before choosing
to implant?
Research and observation suggest that early implantation in children
is closely related to increased outcomes in spoken language development.
Studies also suggest that shortened duration of deafness also positively
impacts spoken language growth with an implant. Given these findings,
waiting for new technology may negate the benefits of cochlear implantation.
If early implantation and shortened duration of deafness are seen
as primary impacting factors on cochlear implant success, then waiting
for new technology would not be recommended.
In addition, as of early 2003, the three major implant manufacturers
have introduced new technologies into the marketplace. It does not
appear that there will be changes to the surgically implanted portion
of the device in the near future. Changes to the devices, should
they occur, will probably be related to external hardware and software
of the systems. Persons obtaining cochlear implants at this time
should therefore be able to take advantage of these advances without
further surgery.
What are the surgical risks?
In general, the surgical procedure is not considered risky. The
risks reported are those associated with any surgery requiring anesthesia.
The areas involved in surgery include the mastoid bone behind the
ear (where the magnet portion of the implant is housed) and the
cochlea housed in the inner ear (where the electrodes are implanted)
. This is not "brain" surgery.
As the hearing system is close to the balance system, some patients
report periods of dizziness following implantation. There are other
possible, though uncommon, risks associated with surgery related
to the facial nerve, sense of taste, and possible infection that
should be discussed with the physician. (Also see the module, Surgical
Considerations.)
What about the possible relationship
between cochlear implants and the risk of meningitis?
On July 24, 2002, the FDA issued a Public Health notification highlighting
the possible association between cochlear implants and subsequent
bacterial meningitis. While the FDA announcement discusses the
possible association between implants and meningitis, it also explains
that the implant has not been proven to be the cause of the meningitis
in the cases noted. The full report, Cochlear Implant Recipients
May Be At Greater Risk For Meningitis, can be found at: http://www.fda.gov/cdrh/safety/020606-cochlear.html.
Related to the possible risk of meningitis, the following should
be taken into consideration:
- any surgery on the inner ear can increase the risk of infectious
diseases like meningitis,
- some deaf individuals may have congenital abnormalities of the
inner ear that make them more prone to meningitis with or without
a cochlear implant, and
- some individuals who are deaf from meningitis may be at an increased
risk for subsequent episodes of meningitis in comparison to the
general population.
Is the residual hearing in the implanted ear destroyed as a
result of surgery?
The design of improved electrode arrays and implantation procedures
seem to be increasing the chance that the cochlea may be preserved
following implantation. There continues to be the potential loss
of residual hearing following implantation, and implant companies
continue to warn patients that implantation will probably result
in the loss of residual hearing.
What about Magnetic Resonance Imaging (MRI) for persons with
cochlear implants?
Implants and MRIs are generally not compatible due the magnetic
component of the implant. The Nucleus 24 device designed by the
Cochlear Corporation has a surgically removable magnet and a design
feature to withstand some MRIs. If MRIs are an issue of concern,
this should be discussed with your hospital implant center. The
MED-EL Device, COMBI 40+, is under investigation for allowing MRIs
under certain conditions.
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