Cochlear implants for severe hearing loss

Cochlear implants are electronic devices that help improve the hearing of adults and children who have severe or profound hearing loss. An operation is carried out to place part of the implant under your skin. They may be useful for people with hearing loss that hasn’t been improved by using conventional hearing aids.

You will meet the audiologist or surgeon carrying out your procedure to discuss your care. It may differ from what is described here as it will be designed to meet your individual needs. Details of the procedure may also vary from country to country.

About cochlear implants

Cochlear implants work differently to conventional hearing aids. Hearing aids make sounds louder so they can be heard by damaged ears. Cochlear implants convert sound waves into electrical signals and direct them past the damaged part of your ear, straight to your auditory nerve.

Your auditory nerve carries electrical signals from your cochlea (in the inner ear) to your brain, which recognises the signals as sounds. This means that cochlear implants don’t rely on your inner ear, where tiny cells called hair cells usually pick up sound vibrations.

If you have severe or profound hearing loss that has been caused by damage to these hair cells and isn’t helped by conventional hearing aids, you may find cochlear implants helpful.

Cochlear implants are made up of an external and an internal part. If you decide to have a cochlear implant, you will need to have an operation to position the internal part, made up of a receiver and electrodes, under your skin and in your inner ear. The electrodes will go from the receiver to your inner ear.

According to the US Food and Drug Administration (FDA), as of December 2010, about 219,000 people worldwide have cochlear implants.

Who can have cochlear implants?

Not everybody benefits from cochlear implants. Cochlear implants may be suitable if you have severe or profound sensorineural hearing loss. This is usually caused by damage to hair cells in your cochlea.

If you have lost your hearing after learning to speak, a cochlear implant may benefit you because you can learn to associate the signal provided by an implant with sounds you remember. They may also help children who are born deaf to develop speech and reach their potential at school.

You will probably need to see several specialists before you can have cochlear implants, which may include an audiologist, speech and language therapist, and an ear, nose and throat (ENT) surgeon. iThe procedure may be done in a hospital or specialist clinic.

You will need to have some tests to make sure a cochlear implant is the best option for you. The tests will check a number of things, including:

• your general health

• your ears and hearing

• your lip-reading and communication skills

• your balance and vision

You may also have a CT scan and an MRI scan so that your specialist can look at your inner ear. A CT scan uses X-rays to make a three-dimensional image of your inner ear. An MRI scan uses magnets and radiowaves to produce images of the inside of your ear.

Cochlear implants won’t restore your hearing but they will allow you to understand sounds. Some people may always need to lip-read as well as listen. Others will learn to understand speech without lip-reading and some people will be able to have telephone conversations.

It’s important to be aware of everything that’s involved with having cochlear implants. This includes understanding about the operation, how you will recover and being prepared for the rehabilitation afterwards.

Rehabilitation will involve working with audiologists and speech and language therapists to help you learn how to understand what you’re hearing. A key part of this process is to talk through your expectations of how you think 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 improve your ability to understand sounds and speech.

Preparing for a cochlear implant operation

Your surgeon will explain how to prepare for your operation. 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.

If you're having a general anaesthetic, 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 surgeon’s advice.

Your surgeon will discuss with you what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen, and you can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure.

This will help you to be informed, so you can give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.

What happens during a cochlear implant operation?

The operation to have the internal receiver placed under your skin and the electrodes fitted will last between three and five hours.

Your surgeon will shave a small patch of hair behind your ear and make a cut in your mastoid bone. This is so a pathway to your middle ear can be created and the electrodes can be threaded through into your cochlea.

He or she will place the receiver in a hollowed-out bed in your temporal bone, just behind your ear. Once your surgeon is happy that the implant is working, he or she will stitch up your cut and place a bandage around your head.

What to expect afterwards

You will need to rest until the effects of the anaesthetic have passed and you may need pain relief to help with any discomfort as the anaesthetic wears off.

Recovery from the operation will vary from person to person, but generally it’s quite quick. You may need to stay in hospital for one or two nights after your operation.

After your operation, you should keep the wound dry for two weeks, so it’s important not to wash your hair. The length of time your dissolvable stitches will take to disappear depends on what type you have. However, for this procedure, they should usually disappear in about two to four weeks.

Recovering from a cochlear implant operation

If you need pain relief, you can take over-the-counter painkillers such as paracetamol (acetaminophen) or ibuprofen. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.

After four to six weeks, you will need to return to the hospital so your external parts (microphone and speech processor) can be connected to the internal parts of your implant. Your audiologist will activate and programme your implant so that it meets your needs. As you get used to using your implant, you will need to have regular check-ups with your audiologist so that he or she can adjust the settings.

What are the risks?

As with every procedure, there are some risks associated with the cochlear implant operation. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your surgeon to explain how these risks apply to you.

Side-effects

Side-effects are the unwanted but mostly temporary effects you may get after having the procedure.

Possible side-effects include:

• temporary dizziness

• temporary tinnitus

• numbness around your scar

• change in taste sensation

Complications

Complications are when problems occur during or after the operation. Complications during or after a cochlear implant operation are rare but can include the following.

• Your implant may stop working, which will mean you will need to have another operation to replace it.

• The nerves in your face, near your wound may become bruised, although this is unlikely because they will be carefully monitored by your surgeon throughout your operation.

• The long-term effects of electrical stimulation aren’t known. However, the amount of electricity used in cochlear implants is very small and there have been no reports of long-term damage.

Living with cochlear implants

Once you have had a cochlear implant, you won’t be able to take part in any activities that may cause a blow to your head, such as football, boxing and rugby. Deep water diving is another activity that you won’t be able to do. This is because the increase in pressure can damage your implant.

When your cochlear implant is switched on, the speech that you hear may sound different to how you remember it. Your speech and language therapist will help you get used to recognising different sounds and words.

Although sound through a cochlear implant isn’t the same as natural sound or sound through a hearing aid, they allow many people to recognise warning signals, understand environmental sounds, and enjoy a conversation.