About Cochlear Implants
A cochlear implant is the most common implanted hearing device and used for severe to profound hearing loss in both ears due to a damaged cochlea or a
An electrode array inserted in the cochlea uses electrical current to stimulate the auditory nerve fibres, bypassing the damaged or missing portions of the middle and inner ear. A microphone, sound processor and transmitter are worn externally. Adults require intensive auditory training with a specialist audiologist and children require auditory-verbal therapy or speech and language pathology.
In the last 20 years the bionic ear or cochlear implant has revolutionised the management of severe to profound hearing loss in both adults and children where hearing aids have not been powerful enough to adequately amplify speech or soft environmental sounds.
For those with sensorineural hearing loss as a result of damage to the inner ear (cochlea), a cochlear implant provides auditory sensation by direct stimulation of the auditory nerve.
A cochlear implant consists of an internal implanted component (c) and an external component. The internal component is surgically inserted under the skin behind the ear and a narrow wire is threaded into the inner ear. The external component, which looks somewhat like a behind-the-ear hearing aid (a), is connected to the internal one through the skin via an external magnetic disk (b).
Incoming sounds are converted to electrical currents and directed to a number of contact points on the internal wire. This operation creates an electrical field which directly stimulates the auditory nerve (which sends the sound information to the higher centres of the brain for interpretation), thus bypassing the defective inner ear.
The cochlear implant has become widely recognized as an established treatment for profound hearing loss.
The surgical procedure, performed under general anaesthetic, takes approximately two hours and requires an overnight stay in hospital. The device is switched on and programmed by a trained audiologist about three weeks after surgery once the wound has healed and any mild soft tissue swelling has settled.
At the switch on, the cochlear implant is connected directly to a computer via a magnetic coil for programming and each of the electrodes to the cochlear are individually programmed. Over the ensuing weeks, the programming is refined as the user becomes more familiar with the implant.
Quick Facts on cochlear implants
- Cochlear implants are medical devices that bypass damaged structures in the inner ear and directly stimulate the auditory nerve. They are surgically implanted to improve hearing in people with severe or profound hearing losses. They can create a range of sound, but do not replace normal hearing.
- Cochlear implants are not indicated for all hard of hearing or deaf people. They are not recommended in people who function well with hearing aids
- Cochlear implants can be provided for children as young as 12 months old, as well as adults.
- Cochlear implants can be in one ear or both (binaural).
- To be considered for a cochlear implant, you will need to receive an evaluation by an audiologist associated with a cochlear implant clinic.
- Ideal candidates are motivated to work hard in their rehabilitation after surgery. It helps to have good family support and to live close to a clinic in order to conveniently make the follow-up trips for mapping and adjustments.
- Adjustments (called “mapping”) are an integral and essential part of cochlear implant rehabilitation. Mapping is done by trained audiologists who adjust the speech processor to help improve hearing.
- Cochlear implant performance varies. People hear better over time with practice. It takes a while to get used to hearing sounds in a new way. Speech processors are computers worn as a behind-the-ear device similar in look to a behind-the-ear hearing aid.
- Use of the phone varies among individuals. Some people plug into the speech processor directly. Others hold the phone up to the ear, while others are not able to use the phone comfortably after their implant.
- Waterproof or water resistant devices are now available.
- A variety of assistive devices can be combined with cochlear implants to improve their effectiveness. For example, patch cords can connect speech processors to assistive listening devices. Also a directional hand-held microphone can be used to improve speech pick-up in noisy environments.
Currently there are three cochlear implant manufacturers with products approved for use in Australia: Advanced Bionics, Cochlear Ltd and MEDEL.
Image of woman wearing blue cochlear implant courtesy of Advanced Bionics