A
cochlear implant is a small electronic device that can help improve the hearing
of people with severe, irreversible hearing loss. A surgeon places the implant
in the inner ear, and it is activated by a component worn outside the ear.
In most people who develop hearing loss, the hairs in the cochlea have become damaged or missing, usually as a result of aging and repeated exposure to loud noises, or for genetic reasons. That disrupts the efficient transmission of electrical signals to the brain, resulting in hearing loss. A cochlear implant bypasses damaged parts of the cochlea and stimulates the auditory nerve directly.
The Cochlear Implant System
● Microphone and transmitter: The transmitter, worn outside the
ear, is approximately the size of a quarter. It picks up sounds, which then
travel to a speech processor.
● Speech processor: A person with a cochlear implant wears their speech
processor externally, either hooked to a belt like a badge or behind their ear
like a hearing aid, to convert sound into a digital code that gets transmitted
to an implanted stimulator.
● Implanted stimulator: The implanted stimulator is a small
component placed under the skin behind the ear. It receives information from
the speech processor and sends it to the auditory nerve. The brain interprets
this signal and recognizes it as sound.
How Does the Cochlear Implant Work?
● First, the microphone on the
external device picks up the sound energy. The speech processor then filters,
analyzes and converts the soundwaves into a digital code.
● That signal travels through
the cable to the headpiece, which transmits it across the skin to the internal
receiver via radio frequencies.
● Then, the internal receiver
sends the signal to the electrodes implanted inside the cochlea.
● The electrodes transmit small
electrical pulses that stimulate the auditory nerve, which attaches to the
cochlea. By triggering the auditory nerve directly, the cochlear implant
circumvents the damaged parts of the cochlea that lead to hearing loss.
● The auditory nerve then carries the electrical signals to the brain, which interprets them as sound. This entire process occurs so quickly that the listener will hear speech and other sounds without any noticeable time lag.
Cochlear Implant Candidates
In
general, the best candidates for cochlear implants share these characteristics:
● Being in good overall health
●Having realistic expectations
for the results of their surgery
● Experiencing profound hearing
loss in both ears
●Are no longer benefiting from
conventional hearing aids
●No medical conditions that
would make surgery too risky
●A willingness to participate in listening and speech therapy
Frequently Asked Questions About Cochlear Implants
If
you're exploring cochlear implants for yourself or your child, our guide to
cochlear implant surgery can help.
Will cochlear implants fully restore
hearing for deaf people?
No, a
cochlear implant is a valuable communication tool, but not a cure for deafness.
When hearing functions normally, parts of the inner ear convert soundwaves into
electrical impulses. These impulses travel to the brain, which interprets them
as sound. A cochlear implant replicates that process. Implants, coupled with
listening therapy, can help people recognize sound, including speech.
What differentiates cochlear implants
from hearing aids?
Hearing
aids work to amplify sound, but people with severe to profound hearing loss may
have trouble understanding speech and other sounds, even with powerful hearing
aids. Cochlear implants bypass the damaged part of the ear and send sound
directly to the hearing nerve.
Given
time and training, most cochlear implant recipients demonstrate improvement in
their ability to understand speech, even in noisy surroundings, compared to
people who wear hearing aids. They may even be able to talk on the phone or
listen to music.
Are cochlear implants safe?
Cochlear
implants have been in use since the 1970s, and several types of devices have
received FDA approval for use in children and adults.
What happens during cochlear implant
surgery?
Cochlear
implant surgery is fairly routine and typically performed under general
anesthesia. The surgeon will make a small incision behind the ear, and will
sometimes need to shave a tiny patch of hair away from the incision site.
Next,
the surgeon places the implant under the skin and inserts the electrode into
the inner ear. The surgeon will close the incisions, often with disposable
stitches, so there may be no need to return later to have your stitches taken
out. Following cochlear implant surgery, the surgical team will perform tests
to measure your response to the implant.
How long does a cochlear implant
operation take?
In most
cases, getting a cochlear implant is an outpatient procedure that takes around
two hours per ear.
Are there risks in cochlear implant
surgery?
Risk is
inherent in any surgery. However, the surgical risks associated with cochlear
implantation are minimal.
If new advances in hearing technology
become available, will I need follow-up surgery to replace my cochlear
implants?
The
implanted unit is a lifetime device. The externally worn speech processor,
which is responsible for translating soundwaves into code and sending the
information to an internal implanted simulator, relies on software that you can
have upgraded as technology improves.
Will my child outgrow the internal
implant and need a new one?
No.
Babies are born with fully formed cochleas, and the skull structures attain
almost complete growth by age 2. The design of the electrode array accounts for
skull growth in younger patients.
Should I wait for cochlear implant
technology to improve?
No, the
design of the surgically implanted receiver and electrode array has changed
relatively little during the history of cochlear implants. However, speech-coding
strategies, which are responsible for delivering the signal to the internal
unit and are stored in the externally worn speech processor, have improved
significantly over the years. The speech processor can incorporate new
technology when available.
Are there any activity restrictions
people who have cochlear implants should be aware of?
People
with implants can shower, swim and enjoy playing virtually any sport when they
are not wearing the external components of their system. The only restrictions
are participating in scuba diving and skydiving, due to the pressure changes
associated with these activities.
You can resume airline travel within a week or two of getting surgery, as long as you don't experience any surgical complications. However, the equipment may activate the metal detectors at the airport, so you'll need to carry your cochlear implant medical ID to help you clear the security screening.