Cochlear
Implants
Insight into an implantable device to help you hear A cochlear implant is
an electronic device that restores partial hearing to the deaf. It is surgically
implanted in the inner ear and activated by a device worn outside the ear.
Unlike a hearing aid, it does not make sound louder or clearer. Instead, the
device bypasses damaged parts of the auditory system and directly stimulates
the nerve of hearing, allowing individuals who are profoundly hearing impaired
to receive sound.
What is normal hearing?
Your ear consists of three parts that play a vital role in hearing—the
external ear, middle ear, and inner ear.
Conductive hearing: Sound travels along the ear canal of the external ear
causing the ear drum to vibrate. Three small bones of the middle ear conduct
this vibration from the ear drum to the cochlea (auditory chamber) of the inner
ear.
Sensorineural hearing: When the three small bones move, they start waves of
fluid in the cochlea, and these waves stimulate more than 16,000 delicate hearing
cells (hair cells). As these hair cells move, they generate an electrical current
in the auditory nerve. It travels through inter-connections to the brain area
that recognizes it as sound.
How is hearing impaired?
If you have disease or obstruction in your external or middle ear, your conductive
hearing may be impaired. Medical or surgical treatment can probably correct
this.
An inner ear problem, however, can result in a sensorineural impairment or
nerve deafness. In most cases, the hair cells are damaged and do not function.
Although many auditory nerve fibers may be intact and can transmit electrical
impulses to the brain, these nerve fibers are unresponsive because of hair
cell damage. Since severe sensorineural hearing loss cannot be corrected with
medicine, it can be treated only with a cochlear implant.
How do cochlear implants work?
Cochlear implants bypass damaged hair cells and convert speech and environmental
sounds into electrical signals and send these signals to the hearing nerve.
The implant consists of a small electronic device, which is surgically implanted
under the skin behind the ear and an external speech processor, which is usually
worn on a belt or in a pocket. A microphone is also worn outside the body as
a headpiece behind the ear to capture incoming sound. The speech processor
translates the sound into distictive electrical signals. These 'codes' travel
up a thin cable to the headpiece and are transmitted across the skin via radio
waves to the implanted electrodes in the cochlea. The electrodes’ signals
stimulate the auditory nerve fibers to send information to the brain where
it is interpreted as meaningful sound.
Who can benefit from an implant?
Implants are designed only for individuals who attain almost no benefit from
a hearing aid. They must be two years of age or older (unless childhood meningitis
is responsible for deafness).
Otolaryngologists (ear, nose, and throat specialists) perform implant surgery,
though not all of them do this procedure. Your local doctor can refer you to
an implant clinic for an evaluation. The evaluation will be done by an implant
team (an otolaryngologist, audiologist, nurse, and others) that will give you
a series of tests:
Ear (otologic) evaluation: The otolaryngologist examines the middle and inner
ear to ensure that no active infection or other abnormality precludes the implant
surgery.
Hearing (audiologic) evaluation: The audiologist performs an extensive hearing
test to find out how much you can hear with and without a hearing aid.
X-ray (radiographic) evaluation: Special X-rays are taken, usually computerized
tomography (CT) or magnetic resonance imaging (MRI) scans, to evaluate your
inner ear bone.
Psychological evaluation: Some patients may need a psychological evaluation
to learn if they can cope with the implant.
Physical examination: Your otolaryngologist also gives a physical examination
to identify any potential problems with the general anesthesia needed for the
implant procedure.
What about surgery?
Implant surgery is performed under general anesthesia and lasts from two to
three hours. An incision is made behind the ear to open the mastoid bone leading
to the middle ear. The procedure may be done as an outpatient, or may require
a stay in the hospital, overnight or for several days, depending on the device
used and the anatomy of the inner ear.
Is there care and training after the operation?
About one month after surgery, your team places the signal processor, microphone,
and implant transmitter outside your ear and adjusts them. They teach you how
to look after the system and how to listen to sound through the implant. Some
implants take longer to fit and require more training. Your team will probably
ask you to come back to the clinic for regular checkups and readjustment of
the speech processor as needed.
What can I expect from an implant?
Cochlear implants do not restore normal hearing, and benefits vary from one
individual to another. Most users find that cochlear implants help them communicate
better through improved lipreading, and over half are able to discriminate
speech without the use of visual cues. There are many factors that contribute
to the degree of benefit a user receives from a cochlear implant, including:
- how long a person has been deaf,
- the number of surviving auditory nerve fibers, and
- a patient’s motivation to learn to hear.
Your team will explain what you can reasonably expect. Before deciding whether
your implant is working well, you need to understand clearly how much time
you must commit. A few patients do not benefit from implants.
How are new implant devices approved?
The Food and Drug Administration (FDA) regulates cochlear implant devices for
both adults and children and approves them only after thorough clinical investigation.
Be sure to ask your otolaryngologist for written information, including brochures
provided by the implant manufacturers. You need to be fully informed about
the benefits and risks of cochlear implants, including how much is known about
how safe, reliable, and effective a device is, how often you must come back
to the clinic for checkups, and whether your insurance company pays for the
procedure.
How much does an implant cost?
More expensive than a hearing aid, the total cost of a cochlear implant including
evaluation, surgery, the device, and rehabilitation is around $30,000. Most
insurance companies provide benefits that cover the cost. (This is true whether
or not the device has received FDA clearance or is still in trial.)
If you have further questions about Cochlear Implants, please feel free to
contact our office.
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Disease
Dizziness
& Motion Sickness
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Earwax
Buildup
Ears,
Altitude & Airplanes
Cochlear
Implants
Ear Aches
Cholesteatoma
Perforated
Eardrum
Swimmer's
Ear
