Published by Bupa's Health Information Team, March 2010.
This factsheet is for people who are considering getting a cochlear implant, or who would like information about them.
The information is relevant for both adults who have hearing loss and parents of children with hearing loss. However, for simplicity we will refer to 'you' throughout.
Cochlear implants are electronic hearing devices that directly stimulate the auditory nerve (the nerve connecting the ear to the brain). They may be useful for people with hearing loss that isn't improved by conventional hearing aids.
Cochlear implants are a type of hearing aid, but instead of making sounds louder like conventional hearing aids, they convert sounds into electrical signals that are sent directly to your brain via the auditory nerve. This means that they don't rely on the inner ear (cochlea) where the hair cells usually pick up sound vibrations. Therefore, you may find cochlear implants helpful if you have severe or profound sensorineural hearing loss that is caused by serious damage to your hair cells, and that isn't helped by regular hearing aids.
Cochlear implants have internal and external parts. An internal receiver is implanted under the skin behind your ear. This is connected by a thin wire to the electrode array, which is surgically inserted into your inner ear. This electrode array takes the place of the hair cells and stimulates your auditory nerve directly.
Externally, you will need to wear a speech processor (containing the batteries), microphone and a transmitter coil - these are connected together with leads. The size of these components varies. You may need to wear the sound processor on a belt but in most modern implants the external components are small enough for you to wear tucked behind your ear (like a conventional behind-the-ear hearing aid).
When sound waves enter the microphone, they are sent as electrical signals to the speech processor. This will have been programmed to suit your needs and turns the signals into a code. The code travels back to the external transmitter coil from where a signal passes through your skin to the internal implant. It then goes along the thin, internal wire to the electrode array in your inner ear.
The electrodes are programmed to detect sounds of varying pitches and so each one picks up a different part of the signal. The electrodes stimulate the auditory nerve and this carries the signal to your brain where it's recognised as sound.
Cochlear implants may be suitable for you if you have severe or profound sensorineural hearing loss that is caused by damage to the hair cells. If you have acquired hearing loss - you lost your hearing after you learned to speak - it's likely that cochlear implants will suit you well. This is because you can probably recall words being spoken and what they sound like. However, cochlear implants can also be very helpful for some children who were born deaf.
If you're considering getting cochlear implants, see your GP. He or she will be able to refer you to a doctor who specialises in identifying and treating hearing disorders such as an ear, nose and throat surgeon. If necessary, this doctor will then be able to put you in touch with a cochlear implant centre.
If you haven't already tried using conventional hearing aids, it's likely that you will first need to wear these for at least three months to see whether they improve your hearing.
If conventional hearing aids don't help, you will be assessed by a team of health professionals. You will need to complete a number of tests and questionnaires. Your hearing and your ability to lip-read will be tested. You will also be asked about your general health to make sure that you're fit enough to have the operation.
It's also important to make sure that you're aware of everything that will be involved in getting cochlear implants. This includes understanding about the operation, recovering from this and being prepared for the rehabilitation afterwards. Rehabilitation will involve working with audiologists and speech and hearing therapists to programme your implants so you can hear sounds, and learning how to understand what you're hearing.
Another key part of this process is to talk through your expectations of how much cochlear implants will be able to improve your hearing. Cochlear implants can't cure deafness or improve your hearing to the level of a healthy ear, but they can offer improvements in your ability to understand sounds and speech.
If you decide to go ahead with cochlear implants, your surgeon will explain how to prepare. For example, if you smoke, you will be asked to stop as smoking increases your risk of getting a chest and wound infection, which can slow your recovery.
The operation is done under general anaesthetic and you will be asked to follow fasting instructions. This means not eating or drinking, typically for about six hours beforehand. However, it's important to follow your anaesthetist's advice.
When you arrive at the hospital, your surgeon will discuss with you what will happen before, during and after your procedure, and any pain you might have. You can ask questions about the risks, benefits and if there are any alternatives to the procedure. This will enable you to give your informed consent for the procedure to go ahead, which you may be asked to do by signing a consent form.
The operation takes between two and five hours. The hair behind your ear will be shaved and an incision made around your ear. Your surgeon will use a drill to make a path through the bone into your middle ear and then to the inner ear. He or she will then make a 'bed' that holds the implant. Once your surgeon has put the implant in place, he or she will carefully insert as many electrodes as possible into your inner ear.
Your audiologist will probably test the implant before closing the wound to make sure that the electrodes are working properly. Your surgeon will then use dissolvable stitches to close the incision.
When you wake up you will have a large bandage around your head and a pack in your ear canal to protect it. You will need to spend at least one night in hospital and before you leave your bandage will be changed for a smaller dressing (usually within 48 hours of the operation). You will probably need to leave the pack in place for about a week, but you will be given a date for an appointment to have it removed.
The operation to insert cochlear implants is generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.
These are the unwanted but mostly temporary effects of a successful procedure, for example feeling sick as a result of the general anaesthetic
Other side-effects that you may have after having a cochlear implant include:
This is when problems occur during or after the procedure. Most people aren't affected, but it's important to be aware of them before going ahead with cochlear implants. Complications of having a cochlear implant include the following.
You may find it takes a while for you to get used to having a cochlear implant. You will need to practise using it, and you may find it frustrating at first. Your audiologist and a team of speech and language therapists will help you get the most from your implant.
For answers to frequently asked questions on this topic, see Common questions.
For sources and links to further information, see Resources.
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This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the About our Health Information page.
Publication date: March 2010
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