What is a cochlear implant?


What is the cochlea?
Is a cochlear implant better than a hearing aid?
How a cochlear implant works
Might I or my child benefit from an implant?
What are the criteria?
Can children born deaf benefit?
What about children who have gone deaf?
How soon should they receive their implant?
Can adults benefit?
What happens during the cochlear implant assessment?
Who carries out the tests?
Who pays for the implant?
What does cochlear implant surgery involve?
How long does the operation take and how long will I be in hospital?
How long will I take to recover?
Are there any risks?
Once the implant is in, does it stay there for life?
Can the patients hear when they wake up after surgery?

What is the cochlea?

The cochlea is the hearing part of the inner ear. It is a biological microphone. Sound vibrations are turned into electrical signals, which travel along the auditory (hearing) nerve to the brain.

Is a cochlear implant better than a hearing aid?

That depends on your hearing loss! Hearing aids work by making ordinary sound louder (‘amplification'). This may be all that is needed for people with mild or moderate-severe hearing losses.
For people with more severe or profound losses, however, making the sounds louder may not help, because the damaged hair cells cannot pick them up. For them, a cochlear implant, which sends an electrical signal directly to the auditory nerve, may be more effective.

How a cochlear implant works

A cochlear implant sends an electrical message through a wire called an electrode directly to the auditory nerve, bypassing the damaged or absent hair cells. This means that, provided the auditory nerve is still working, profoundly deaf people can hear sound. The cochlear implant consists of two parts, a surgically implanted internal part and an externally worn part called a processor.

Might I or my child benefit from an implant?

A detailed assessment is needed to find out whether someone is likely to benefit from a cochlear implant. The assessments are carried out by the cochlear implant team at the National Cochlear Implant Programme in Beaumont Hospital, Dublin.

What are the criteria?

As a general guideline, to be considered for an implant you need to meet the following criteria:
Severe to profound sensorineural hearing loss in both ears
Receive only marginal benefit from hearing aids
Medically suitable for surgery
Strongly motivated
Having a good support network from family, friends, or other professionals
The implant team assesses each case individually and will look at these issues and at other factors which will affect whether or not you or your child are likely to benefit from a cochlear implant.

Can children born deaf benefit?

Children who receive implants when very young, ideally before they reach school age, usually do very well with their implants.
Children implanted over 5-7 years of age who were born profoundly deaf and have been unable to make use of hearing aids are less likely to receive significant benefit. This is because the brain learns to interpret sound most effectively in the first few years of life.
However, older children and adults, who have made good use of hearing aids and have spoken language skills, may be able to benefit from an implant.

What about children who have gone deaf?

Children who were born hearing, or with minor hearing losses, but whose hearing has deteriorated to severe or profound can do well with a cochlear implant.

How soon should they receive their implant?

The sooner they receive their implant after the onset of deafness, the better they are likely to do. Cochlear implants have been helpful for thousands of children worldwide who have lost their hearing for different reasons, including meningitis.

Can adults benefit?

Adults who have lost their hearing can greatly benefit from a cochlear implant. As with children, the sooner they receive their implant after a severe to profound sensorineural hearing loss is diagnosed, the more benefit they are likely to receive from the sound from the cochlear implant.
Adults who have been deaf since early childhood and who have limited or no memory of sound and speech, are unlikely to receive much benefit from a cochlear implant.

What happens during the cochlear implant assessment?

During the assessment, members of the team will carry out a range of tests and spend time discussing all aspects of implantation with you, in order to ascertain whether you, or your child, might benefit from an implant.
The tests usually include:
Detailed hearing assessments
A hearing aid trial to determine benefit with appropriately fitted amplification
Children are fitted by their local HSE audiology provider
Adults can be fitted by the CI Department if their current hearing aids are not found to be appropriate for their hearing loss
Attending a private hearing aid dispenser is at the discretion of the parent/guardian or patient though this will not speed up the assessment process
Medical examinations
MRI and CT scans (specialised photographs of the inner ear and hearing pathways)
Measures of speech, language and overall communication ability
Measures of listening/lip-reading skills
Other parts of the assessment process include:
Counselling sessions completed during assessment appointments to provide information about cochlear implants and the pre- and post-implant management
Parent-centered group information sessions for parents of children
Pre-operative information session for adults and their family/friends
Introduction to parents/guardians of a child with an implant or to an adult implant recipient

Who carries out the tests?

Members of our cochlear implant team, who are all specialists in their own fields. The team will usually include:
Surgeon
Audiological scientists
Speech and language therapist
Teacher of the deaf for children
Other experts, such as radiologists and psychologists, are also involved

Who pays for the implant?

The Department of Health pays for the full cost of assessment, surgery, cochlear implant system (internal and external device), and follow up-management.
The patient/family is responsible for travel costs, accommodation, and hospital fees (e.g. bed charge when admitted to hospital for surgery/tests). Post implantation, the patient/family will need to purchase and supply batteries to power the external processor.

What does cochlear implant surgery involve?

During the surgery, the surgeon inserts the internal parts of the cochlear implant underneath the skin. The receiver/stimulator sits in the bone just behind the ear and the electrode array is inserted into the cochlea. The electrode array has been especially designed to be thin, tapered and flexible, so that it can slide into the cochlea without causing damage.

How long does the operation take and how long will I be in hospital?

The operation takes around 2-3 hours. The patient generally is admitted the day before the surgery date and spends 3 to 7 days in hospital. This includes pre and post-operative care. In some cases, adults are admitted on the day of the surgery.
Persons with a more complex medical history (eg. diabetic, on autoimmune therapies, etc) will be admitted a few days prior to the scheduled surgery date.

How long will I take to recover?

Recovery rates vary across individuals but most people report feeling well 24 to 48 hours after surgery. Once released from hospital, children usually return to school and adults to work after within a week or two.

Are there any risks?

The risks associated with cochlear implant surgery include:
Risks associated with the use of general anaesthetic, as for any surgery
Risks of inflammation, infection, disturbance or damage to the facial nerve
Stiffness or numbness around the ear
Disturbance of taste or balance
Possible changes in head noises (tinnitus)
Increased risk of meningitis (You will be advised to obtain vaccinations for meningitis prior to surgery as there have been some reports that patients with cochlear implants or inner ear malformations may have a higher risk of meningitis. The vaccinations reduce the risk.)

While it is important to be aware that these complications can occur, in practice there have been very few significant negative side effects reported worldwide for people receiving a cochlear implant. These risks are the same as for any other surgery carried out in this area of the body, and all surgery carries some degree of risk, however minor. The cochlear implant surgeon will discuss the risks with you in more detail before the surgery.

Once the implant is in, does it stay there for life?

The internal part of the CI system is designed to last one's lifetime. However, it is possible that the implant could break down and need to be replaced. If you are concerned about this, ask a member of the team for more up to date and detailed information.

Can the patients hear when they wake up after surgery?

Not yet! The surgeon has only fitted the internal parts of the device. There is a wait of 3 to 6 weeks after surgery, to allow any swelling or tenderness around the implant site to subside, before the external parts of the device can be fitted.
A training programme has been devised by the team to help you get the best from your implant. A commitment to attend all appointments prior to and after implantation must be undertaken.
Doctors are not able to accurately predict how much you will be able to hear with your speech processor - at worst you may only get an awareness of sounds around you and some help with lip-reading. You may, on the other hand, get a much better result.

 


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