| Understanding Cochlear
Implants |
This booklet is
designed to supplement the information
pack which MED-EL has supplied to your
Cochlear Implant Team. You may already
have worked through all or part of that
pack with someone from your Implant
Team, in which case this booklet will
act as a reminder of what you have covered/
or you may be reading this in advance
of such discussions with your Implant
Team.
In this booklet we will look at the
ear and how we hear/ the causes and
treatments of hearing loss; then we
focus on the cochlear implant system,
how it works/ who can benefit from it
and the general steps involved in obtaining
an implant if, indeed, it is the appropriate
treatment for you or your family member.
If you need any further information
or explanation, please ask your Cochlear
Implant Team. |
 |
| The Ear? |
| There are 3 main
parts to the ear: |
|
| 1-Outer Ear |
| The ear or pinna
which helps us to tell where sound is
coming from. The ear canal (the part
where ear wax can collect) which acts
as a channel for sound |
|
| 2-Middle Ear |
The ear drum or
tympanic membrane is taut, like the
skin of a real drum, turns sound into
vibrations. A chain of 3 small bones,
the hammer/ anvil and stirrup,
or malleus, incus and stapes. These
bones pass vibrations on to the inner
ear. |
|
| 3-Inner Ear |
snail-shaped
and filled with fluid. It contains
very sensitive cells, called hair
cells, which have a tiny hair-like
structure on the top of each cell.
These hair cells play a very important
part in enabling us to hear. The vestibule
contain. the delicate cells which
enable us to have a sense of balance.
and auditor leading from the cochlea
to the brain. |
|
| How we hear? |
| Sound travels down
the ear canal and hits the ear drum.
The ear drum is taut, like the skin
of a real drum and it vibrates when
sound hits it. This vibration is passed
down the chain of bones to the cochlea
(the inner ear). The vibrations make
the fluid in the cochlea move. . This
movement in turn makes the hair cells
move. When this happens the hair cells
make tiny electrical signals which are
picked up by the auditory nerve. Hair
ceils at one end of the cochlea send
low pitch sound information in these
signals and those at the other end send
high pitch sound information. These
electrical signals pass up the nerve
to the brain.The brain interprets the
electrical signals as sounds. |
|
| Why people have hearing
difficulties? |
|
| Conductive hearing
loss |
| Any problem in
the outer or middle ear can block sound
to the ear and cause a conductive hearing
loss (so called as it stops the ear
from conducting sound properly). Conductive
losses are usually mild or moderate
in nature/ i.e. causing hearing loss
of up to about 60 or 70 decibels. Conductive
hearing losses can be temporary in some
cases. In many cases medication or surgery
can help, depending on the cause of
the problem. This type of hearing loss
can usually be helped very well with
hearing aids. |
|
| Conductive hearing
loss is due to : |
|
| A problem in the
OUTER or MIDDLE EAR. |
| Sensorineural hearing
loss |
| A problem in the
inner ear can cause a sensorineural
hearing loss. This can be mild, moderate,
severe/ profound or even total hearing
loss. Sensorineural losses are usually
permanent. There is no surgical procedure
to cure problems in this part of the
ear; depending on the cause, medication
may be helpful in some cases. Conventional
hearing aids can usually help in mild
to severe hearing loss. Cochlear implants
can be a very effective option for those
with severe/ profound or total hearing
loss/ meaning those people who are not
able to gain sufficient speech information
even with the most powerful hearing
aids. |
|
| Sensorineural hearing
loss is due to: |
| A problem in the
INNER EAR or COCHLEA. |
|
| Neural hearing loss |
| In very rare cases
hearing loss may be caused by the absence
of or damage to the auditory nerve,
resulting in a neural hearing loss.
Conventional hearing aids will give
little benefit because the nerve is
not able to pass on enough information
to the brain. A cochlear implant will
not help unless there is some auditory
nerve function. An auditory brainstem
implant will help in some cases. |
|
| Neural hearing loss
is due to: |
| A problem in the
NERVE PATHWAY. |
|
| Who can benefit from
a Cochlear Implant? |
| Cochlear implants
are only appropriate for hearing losses
primarily caused by a problem in the
inner ear (the cochlea). They are intended
for people who are unable to gain sufficient
speech information through conventional
hearing aids. Both children and adults
can use cochlear implants effectively,
whether they are born deaf or whether
hearing loss occurs later in life. It
is not possible to predict how much
benefit any individual will get from
a cochlear implant, but the following
points are widely recognized: The longer
the period of profound deafness, the
more limited the benefits are likely
to be. Born deaf children will have
the greatest benefit if they have an
implant before the age of 5 and preferably
by the age of 3. If a person has memory
of speech and language they may have
more benefit from a cochlear implant.
|
|
| How a Cochlear Implant
works? |
| 1. Sounds are picked
up by a microphone and turned into an
electrical signal.
2. This signal goes to the speech
processor where it is "coded"
(turned into a special pattern of
electrical pulses).
3. These pulses are sent to the coil
and are then transmitted across the
intact skin (by radio waves) to the
implant.
4. The implant sends a pattern of
electrical pulses to the electrodes
in the cochlea.
5. The auditory nerve picks up these
tiny electrical pulses and sends them
to the brain.
6. The brain recognizes these signals
as sound.
|
|
| Why might a Cochlear
Implant not be suitable? |
| A range of common
reasons include: |
|
| 1-Your hearing is
"too good" |
| The most common
reason for not needing a cochlear implant
is that the hearing is too "good"'.
If a person can hear enough of the sounds
of speech through well-fitting hearing
aids, even if they need lip-reading
to aid their understanding, this .will
normally be the best option for them. |
|
| You have been profoundly
deaf for a very long time |
| If the auditory
nerve has never been stimulated or has
not been stimulated for a very long
time, it may not pass sound information
to the brain very well even with a cochlear
implant. The brain also needs experience
of understanding sounds from childhood
on in order to optimally utilize any
information a cochlear implant can provide. |
|
| The cochlea is not
the main cause of the hearing loss |
| A cochlear implant
is designed to make up for poor inner
ear function. A cochlear implant cannot
help if the main problem lies elsewhere. |
|
| Surgery is not likely
to be successful |
| The cochlea may
be in too poor a condition to receive
the electrode. For example, the auditory
nerve may be damaged or absent, in which
case a standard cochlear implant would,
not help. |
|
| Medically Unfit |
| A patient needs
to be well enough to undergo surgery,
to tolerate and recover from the unaesthetic
and the surgery. In some cases the operation
can be carried out under powerful local
unaesthetic for adults. He or she must
also be well enough to and capable of
undergoing the follow-up program necessary
to use the implant well, including wearing
the external parts of the device, having
the speech processor programmed and
being involved in the rehabilitation
program. |
|
| Inappropriate expectations
of how the patient might benefit from
a cochlear implant |
| It is essential
that realistic expectations of the likely
benefits are held by the patient and
family. What to expect and what not
to expect should be discussed thoroughly
with the implant team. |
|
| Lack of support from
family or care-givers |
| Support from family
and care-givers is important and indeed
vital in the case of children with cochlear
implants. Having a cochlear implant
is a commitment for the lifetime of
the individual concerned. Patients will
only achieve optimum results, if their
device is well programmed, fully functioning
and if they go through a rehabilitation
program designed for them by the implant
team specialists. |
|
| The benefits of Cochlear
Implants |
|
| Hearing everyday sounds |
| Virtually all users
benefit by being able to hear more environmental
sounds. This helps people to keep in
touch with their environment. It is
also an important safety consideration
as it enables people to hear traffic,
sirens, alarms and so on. |
|
| Hearing and understanding
speech |
| Virtually all users
will hear speech sounds through the
cochlear implant. It usually takes some
time before they begin to understand
these sounds, especially for children.
Being able to hear speech can be of
great help to those who lip-read, and
it makes everyday communication much
easier for the vast majority of users.
Furthermore, users may go on to understand
speech without lip-reading. Many, although
not all, cochlear implant users do achieve
this with time. |
|
| Improving the user's
own speech |
Hearing their own
speech and the speech of others often
helps cochlear implant users to fine-tune
their speech.
Hearing their own speech and the speech
of others often helps cochlear implant
users to fine-tune their speech. |
|
| Listening in background
noise |
| When there is background
noise/ it is more difficult for all
of us to hear speech, but especially
so for hearing aid and cochlear implant
users. The COMBI 40+ cochlear implant
has special features to help in this,
including its fast stimulation rate
and advanced speech processing strategy,
providing outstanding speech understanding
in back-ground noise. |
|
| Using the phone can
become a reality! |
| Many users are
eventually able to understand speech
without lip-reading. Some users also
go on to be able to have inter-active
conversations over the telephone. |
|
| The limitations of
Cochlear Implants? |
| There is a wide
range of benefits obtained from cochlear
implants. Benefits range from an aid
in lip-reading to understanding speech
without lip-reading. |
|
| Prediction of benefit |
| There is no test
yet available which accurately predicts
how much benefit any particular person
will receive. Many factors affect the
likely benefits to be derived. They
are discussed in the section "Who
can benefit from a cochlear implant". |
|
| Risk of device failure |
| As with any technical
device there is a small risk that the
implant could break down. This rarely
occurs, but when it has done, re-implantation
with a new implant has been highly successful. |
|
| Everyday considerations
and precautions |
| The system is easy
to use but certain precautions should
be taken:
• Keep the external parts of
the device dry (as with hearing aids)
• Avoid activities and sports
which could cause a severe blow to
the head
• Keep exposure to static electricity
as low as possible
• Sources of radio frequencies
(e.g. mobile phones) can cause some
temporary interference with the sound
through the implant for some users
• Cochlear implant users can
continue to participate in most everyday
activities; sports such as boxing,
however, are not advised! |
|
| The MED-EL COMBI 40+ |
| The Next Generation
Cochlear Implant System |
|
| Components: |
| The COMBI 40+ electrode
array |
| Available in 3
types |
| 1-standard array: |
The longest electrode
array on the market,
reaches deep into the cochlea to stimulate
as many of the
auditory nerve endings as possible. |
| 2-short array: |
| Specially designed
for ossified or malformed cochleae. |
| 3-split electrode
array: |
| For highly ossified
cochleae. |
|
| A correct implementation
of the CIS Strategy is crucial for optimum
results. |
The COMBI 40+ system
optimally implements the CIS
strategy because it uses uses digital
filters and can stimulate at high rates,
provides new information in each pulse,
allows the use of a Behind-The-Ear speech
processor, implements technical parameters
correctly, has flexible stimulation
parameters and ensures that stimulation
pulses are non-overlapping. |
|
| The MED-EL COMBI 40+ |
| The Next Generation
Cochlear Implant System. |
| Research has shown
unprecedented levels of speech understanding.
Although it is difficult to compare
studies of speech discrimination tests,
MED-EL devices have consistently achieved
unparalleled results. Preliminary studies
indicate that results are even better
with the new MED-EL CIS-r- Processor
TEMPO+4. |
|
| Speech processing
strategies |
The "speech
processing strategy" is a special
code used to turn sound into a pattern
of electrical pulses. These electrical
pulses are then sent to the electrode
in the cochlea, from which they are
picked up by the auditory nerve. The
aim of the speech processing strategy
is to represent speech as naturally
as possible. The speech processor contains
the electronics that determine which
strategy will be used. With the MED-EL
COMBI 40+, the strategy can be updated
as advances are made, and re-implantation
is not necessary. The MED-EL COMBI 40+
uses fast-rate CIS (Continuous Interleaved
Sampling), because it is very fast,
representing speech more naturally;
results obtained by users prove its
outstanding
effectiveness and it is the most advanced
strategy available. The MED-EL COMBI
40+ also offers Fast Spectral Peak("n-of-m")
which users can choose if they prefer
it (with the CIS PRO+ Speech Processor).
Both strategies available with the MED-EL
COMBI 40+ are clinically proven to be
effective. |
|
| The role of the Cochlear
Implant Team |
| Cochlear implantation
is undertaken within specialist centres,
to which patients are commonly referred
by their local doctor or Ear, Nose and
Throat Specialist. |
|
Cochlear
Implant Team members may include:
|
Their
role |
| |
|
| Specialist
Ear, Nose & Throat Surgeons. |
Medical
evaluation Surgery . |
| Audiological
Scientists Clinical Audiologists
|
Evaluation
of hearing abilities |
| Clinical
Audiologists |
Processor
fitting, programming and follow-up
|
| Speech
& Language Therapists |
Evaluation
of speech and language status
Rehabilitation and Support |
| Educators/
Teachers of the Deaf |
Evaluation of educational, support
needs, Rehabilitation and Support |
| Medical
Physicists |
Technical
support |
| Educational
Psychologist |
Evaluation
of psychological
status, Support |
| Administrative
Staff |
Administration |
Implant Team
Coordinator
|
Coordination
of activities |
|
|
| Assessments involved |
|
| Audiological |
| Hearing levels
with and without hearing aids, for tones
and, or noise, for speech. Test of auditory
nerve function. Establishing existence
of any significant additional conditions
or needs. Establishing appropriate expectations.
|
|
| Medical |
Evaluation of
cause of hearing loss, General health,
Condition of the ears, Establishing
existence of any significant additional
conditions or needs, Establishing
appropriate expectations. |
|
| Radiological |
| CT and, or MRI
scan of the ears . |
|
| Psychological |
| Ability to cope
with operation "try to cope with
follow-up program. Establishing existence
of any significant additional conditions
or needs. Establishing appropriate expectations. |
|
| Speech & Language |
| Assessing stage
of speech & language: stablishing
existence of any significant additional
conditions or needs. Establishing appropriate
expectations. |
|
| Educational |
| Assessing stage
of development of child, Establishing
existence of any significant additional
conditions or needs, Establishing appropriate
expectations. |
|
| The operation |
The operation usually
takes between 2 and 4 hours. The risks
involved in cochlear implant surgery
are small and compare well
with other ear surgeries.
1. A general anaesthetic is normally
given.
2. The skin is shaved around where
the incision is to be made.
3. The incision is made and the skirl
and tissue are lifted back to expose
the skull.
4. A bed is drilled out in the bone
behind the ear for the implant.
5. A hole is drilled into the cochlea.
6. The electrode array is inserted
into the cochlea.
7. The electrode array and the implant
itself are secured in place.
8. The skin and tissue are reattached,
and the wound is stitched up.
9. There is usually little discomfort
when the patient wakes up. Pain medication
can normally be given if required.
:
10. Patients are usually up and about
the next day. The length of stay in
the hospital depends upon local practice
and can be as short as 3 days. |
|
| First sounds through
the cochlear implant |
The speech processor
is fitted 3 to 6 weeks after surgery.
The
speech processor is set up individually
for each user.
To program the processor for the
user:
• the user wears the processor,
• the processor is also attached
to the clinic computer,
• the clinic computer generates
signals at carefully controlled levels,
• the user indicates:
- the quietest signal heard (his
THRESHOLD level)
- the loudest comfortable signal
heard (his MOST
COMFORTABLE level)
• these two levels are measured
for all the electrodes in the cochlea,
• using this information a
speech processor program is created
which allocates sounds between these
two levels, i.e. loud enough to hear
but not so loud as to be uncomfortable.
The program is fine-tuned during following
clinic sessions. |
|
| The follow up program |
| The cochlear implant
user needs to be fully committed to
the follow-up program designed by the
Cochlear Implant team in order to benefit
most from the implant system. The follow-up
program will depend on local practices
but may include: |
|
| Availability of help,
advice and support |
| Assistance should
be available not only for technical
matters which may arise, but also for
general questions. The team can also
give you information on support groups
for cochlear implant users and their
families. |
|
| Regular medical check-ups |
| The implant site
should be checked regularly by a physician. |
|
| Regular reprogramming
of the speech processor |
Cochlear implant
users should visit their clinic regularly
for repro-
gramming of the speech processor. This
allows the audiologist to
check that the implant is continuing
to function well. He can also
make any small modifications or improvements
to the program so
that the user will continue to have
the greatest benefit from the
implant system. |
|
| Speech and language
therapy and advice |
| Regular speech
and language therapy is usually available,
especially for children. |
|
| Educational advice
and support (for children) |
| Children using
cochlear implants usually have regular
contact with an educational specialist
qualified to work with the hearing impaired.
He or she can offer advice and support
and monitor the child's progress with
the cochlear implant system. |
|
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