Cochlear Implants for Adults
David Schramm MD FRCSC FACS
Josée Chénier M.O.A.
Shelly Armstrong M.Cl.Sc.
Ottawa Hospital, Civic Campus
At the Ottawa Hospital, we have had a Cochlear Implant Program since 1993. At
present a total of 190 adults have received implants at our center including
people from Ontario, Quebec, the Maritimes and Manitoba.
A cochlear implant is a surgically implanted device for people who get
limited benefit from hearing aids. Before one can understand how a cochlear
implant works, it is important to understand how the ear normally works.
Sound enters through the ear canal and strikes the eardrum. The sound is
passed through the three bones. The last bone, the stapes, is connected to the
cochlea so that when it moves, it causes the fluid inside the cochlea to
vibrate. The cochlea is a fluid filled sac that contains tens of thousands of
hair cells which can sense the movement of the fluid. When these hair cells are
stimulated, they generate electrical impulses that travel down the hearing
nerves into the brain. The brain discriminates sounds from one another and
eventually associates words with ideas.
Most hearing loss is caused when the hair cells are not working. Because the
hair cells are damaged, the ear is not able to convert sound vibration into
electrical impulses to the brain.
A cochlear implant is a device that is surgically implanted in people with
severe to profound hearing loss. It has both internal and external components.
The internal components are comprised of the electrode array and a receiver
stimulator. The external components are comprised of the speech processor,
headset and transmitting cable.
The microphone picks up sound and changes it into electrical signals. The
signal is sent to the speech processor by the transmitting cable.
The speech processor changes the signal into digital pulses. These pulses are
sent back to the headset and to the electrodes implanted in the cochlea.
The electrodes stimulate the auditory nerve that sends the electrical pulses
to the brain.
Extensive testing is required before surgery to ensure that you are a
candidate for a cochlear implant and that you would benefit from such an
Hearing tests, before and after, measure your progress with words and sounds.
A candidate for a cochlear implant, typically:
- has a severe to profound hearing loss in both ears
- receives limited benefit from hearing aids
- finds telephone use difficult, limited or impossible
- relies heavily on speech reading or note writing
- has no medical contraindications
The above mentioned difficulties are primarily due to the hearing loss
resulting in a lack of clarity of speech.
There is a wide range of benefits from cochlear implants among large groups
of implant users. Essentially all cochlear implant users have more awareness of
sounds and are able to speech-read easier. Many people who use cochlear implants
are able to understand some speech through listening alone. The amount of speech
understanding in a quiet environment can vary from 0% to 100%.
There are many factors affecting the amount of clarity an individual will
receive with an implant. These factors include age, duration of deafness,
language, other handicaps, motivation, and use of spoken language as their
primary means of communication.
Age is not a limiting factor to receive a cochlear implant. One must be
healthy enough to undergo surgery. This criteria would be determined by Dr.
Schramm and the hospital pre-admission staff that consists of physicians and
medical professionals. The oldest person implanted at our center is 85 years
old. An older individual may take more recovery time after surgery and may take
more time to adapt to the new sound of the implant. However the person may still
benefit from an implant and it could have a major impact on his/her quality of
In general, people who have had severe to profound deafness for many years
may take longer to obtain the full benefit from their cochlear implant. Also,
this person may not be able to get as much speech understanding through hearing
alone compared to someone who lost their hearing more recently.
Language can affect outcome with a cochlear implant in two ways. First, if a
person has had hearing loss since birth and has limited vocabulary or knowledge
of language, a cochlear implant alone will not improve the individual’s
language ability without rehabilitation.
Secondly, if the person does not speak English or French, they may still be
considered for an implant. The most improvement in communication ability will be
seen in their primary language. The services of an interpreter would be required
during the assessment and follow-up appointments.
If other handicaps are present, a cochlear implant may still be considered.
Depending on the extent of the other handicaps, expectations from the cochlear
implant may need to be modified.
Results from the cochlear implant are not immediate. There is a learning
process. It takes time for the person to adapt to the new sound and to associate
sound with meaning. To be successful with an implant, motivation is important.
The person considering an implant needs to be willing to put time and effort
towards adapting to the new way of hearing. Perseverance is necessary.
It is important that the person considering an implant have some spoken
language and some involvement in the hearing world. A cochlear implant has the
best outcome when people have had access to hearing either from a progressive
hearing loss or hearing aids. If an individual has not heard sounds for many
years and does not communicate via speaking, they will have more limited benefit
from an implant.
The medical assessment includes case history, examination of the ear, CT scan
of the ears and ENG (or balance test). MRI of the ears or promontory stimulation
may also be necessary. Sometimes referral to other specialists may be required.
A complete hearing assessment would be completed including tests that assess
speech understanding with hearing aids. Counseling would be completed to discuss
different types of implant systems and expectations from the implant.
The surgery requires that the patient be admitted to the hospital for an
overnight stay. A general anesthetic is required. The surgery takes 3 – 4
In our experience of over 360 implants including both adults and children,
the risks of cochlear implant surgery are minimal.
- facial nerve injury (<1/300 to 1/500)
- small possibility of infection
- the small amount of hearing in the operated ear will be lost
- some discomfort or numbness around the implanted ear can occur after
- dizziness, tinnitus or taste disturbance may happen but are generally
Precautions are to be taken if getting an MRI after surgery.
During the surgery the electrode array is placed inside the cochlea. The
cochlear implant is checked during surgery to insure proper function. An x-ray
is completed immediately after the surgery to confirm the position of the
Five weeks is generally allowed for healing. During these five weeks, a
hearing aid cannot be used in the implanted ear due to the loss of hearing.
After five weeks, the external device is programmed and activated.
Adjustments are made regularly based on patient feedback. Often people are
disappointed when the system is first turned on, reporting that it sounds like
static or robotic speech. However, within weeks, the static will turn into
sounds and words. Rehabilitation is often required to help the patient make use
of the new sound. Regular follow up appointments are required.
People report that some sounds are wonderful to hear such as birds and music.
And, some sounds are not so wonderful such as traffic and flushing toilet.
Generally when patients are tested with some sentences through listening
alone in quiet prior to obtaining a cochlear implant, they get minimal results
if any in some cases. However, when tested later on with their implant with the
same type of sentences, there is usually a significant difference. It is to be
noted that there is some individual variability. It also shows that in general,
people are able to understand more speech from cochlear implants compared to
their hearing aids, when no speech reading cues are available.
When patients are tested in noise with the same type of sentences,
performance decreases but in general tends to be better than with hearing aids.
There is a range of potential benefits with a cochlear implant including:
- Better speech understanding compared to a hearing aid
- Ability to talk on the phone
- Better appreciation of music
- Environmental awareness and responsiveness
- Less dependence on family members for day-to-day living.
- Reconnection with the world of sound
- Facilitation of communication with family and loved ones
People with cochlear implants often report less loneliness, depression and
social isolation. They often have more independence, self-esteem, social
interaction and job opportunities.
Although there are many positive aspects to receiving a cochlear implant,
there are also some drawbacks. Cochlear implants are electronic devices. Similar
to a hearing aid, at times, the external pieces malfunction and require
Cochlear implant recipients and/or their families may have unreasonable
expectations wanting to understand speech from listening alone and not using
People with cochlear implants do not have normal hearing. They often still
struggle to hear in difficult listening situations such as when distance and
background noise are present.
It is a myth that cochlear implants restore normal hearing however the
reality is that they can provide improved speech perception and sound quality.
After cochlear implantation, there is a learning process to obtain the maximum
benefit from the device. When the speech processor is off, there is no sound.
Choosing to get a cochlear implant is a very personal decision and it is a
process that needs to be examined with the cochlear implant team. If you have
any questions, please do not hesitate to contact the Ottawa Hospital, Civic
Phone: (613) 798-5555 ext. 18003
TTY: (613) 761-4948
FAX: (613) 761-4312