Not all deaf children benefit from conventional hearing aids. Fortunately there is a solution for some profoundly deaf children or those with total sensori-neural hearing loss who are not able to gain sufficient auditory information to acquire verbal communication: a 22-channel cochlear implant.
Many people are deaf because their inner ear is damaged. Most of them still have some remaining nerve fibres in the ear. These nerve fibres may be capable of sending impulses (sound) to the brain if they are stimulated electronically.
The cochlear implant can do just that. During cochlear implantation an electrical apparatus is surgically implanted into the bone behind the ear. It consists of a microphone (which receives sounds), a speech processor (which selects usable sounds) and a coil (which decodes and sends electric impulses to the electrodes). These components are worn externally.
The electrical impulses are transmitted via 22 implanted electrodes in the cochlear to the audiotory nerve. The internal components include the electrodes implanted in the cochlea. The electrodes are attached to a receiver/stimulator and an internal magnet. The impulses are then interpreted by the brain as sound and a sensation of hearing is experienced.
For the first time the deaf person who has received a cochlear implant will be able to identify normal, daily environmental sounds for example the doorbell, a dog barking, a knock on the door, car engines and hooters, a telephone ringing and background music.
Most children can recognise the rhythm and intonation of speech patterns and can identify some words. Their auditory skills also improve. It can also help the child to recognise speech even without lip-reading in some cases. This is not always the case, as individual children differ widely in the benefit that they receive from the cochlear implant.
The cochlear implant has its limits. The apparatus does not normalise hearing and the sound that is generated by the implant differs from normal hearing.
It is essential that a person who has received a cochlear implant receive intensive hearing and communication training from professionals who are experienced in working with the deaf. The child needs help in order to interpret the sounds he or she hears and, if possible, to use the sound to develop spoken language.
The Carel du Toit Centre at Tygerberg Hospital offers this service. For more information regarding cochlear implants, contact them at (021) 938 5312 or the Cochlear Implant Unit at (021) 938 9494/938 5080.
There are strict selection criteria for candidates of cochlear implants. The selection criteria are:
- Profound or total sensori-neural hearing loss in both ears
- Little or no benefit from hearing aids
- The child must be 18 months or older
- The family must be motivated and supportive and show realistic expectations
- For adults the criteria is also that she had lost her hearing after she had learnt a spoken language.
At the Cochlear Implant Programme at Tygerberg Hospital, a multi-disciplinary team is involved in the selection process. The team includes an ear, nose and throat specialist, audiologist, speech therapist, teacher, guidance therapist, occupational therapist, clinical psychologist and a social worker.
Since 1986 the Cochlear Implant Unit has made it possible for profoundly deaf people to experience the wonder of sound.
In September 1988 the first two deaf children received the Nuceus 22 Cochlear Implant at Tygerberg Hospital.
To date more than 30 000 children and adults worldwide have received a cochlear implant – a new lease on life for most of them.