New Scientist vol 162 issue 2183
- 24 April 1999, page 52Cochlear implants may not be the best way to help deaf children, says Marion Beard
WHEN children learn to talk, they need to be able to hear. So for children who are diagnosed profoundly deaf, doctors are now cushioning the parents' distress by offering to implant a device into the cochlea that will give the child at least some sense of hearing. Reassuring as this may be for parents with normal hearing, it could be depriving deaf children of their most natural and effective means of communication.
Cochlear implants work by bypassing the defective parts of the inner ear and directing signals straight to the auditory nerve. The surgeon installs a titanium or ceramic package into the skull immediately behind the ear, and threads an array of electrodes from there into the spiral-shaped cochlea of the inner ear, where they stimulate the nerve. The child wears a microphone linked to a microprocessor that is programmed to extract the features most relevant to understanding speech. This signal passes across the scalp via a radio link from a transmitter coil to the implant itself.
Cochlear implants have been generally available for around 10 years (This Week, 29 July 1989, p 20), and by the end of 1998, 8000 children worldwide were using implants. Last year, 43 per cent of the children receiving implants were under four years old. In the operation to insert the implant, which takes between three and four hours, the surgeon drills within millimetres of the facial nerve. If this is damaged, the result can be permanent paralysis of one side of the face—a substantial handicap for anyone, but even worse for someone with impaired speech, who will depend heavily on facial expression for communication. Fortunately this complication is rare, but scarring is permanent.
The child wears a box containing the speech processor with cabling and a headset consisting of a microphone resting on the ear and the transmitter coil. The electronics around the ear can get in the way as clothing is pulled on. There is a small increase in the risk of brain injury if the child hits his or her head, as the skull is made thinner where it accommodates the implant. Parents are advised that when the implant is in place their child should not play contact sports, such as rugby or judo. But perhaps more importantly, having to wear this paraphernalia makes the child stand out as different. The effects of this "social mutilation" may emerge as the first generation of children with implants starts to reach adulthood over the coming decade. The child with an implant is not guaranteed intelligible speech. The majority continue to sound "deaf" despite intensive training, and some are unable to express themselves in speech.
There is an alternative. Deaf children can be brought up to use sign language as their first language, and only later introduced to spoken language. This bilingual approach gives a child success in communicating early in life. Native sign-language users—that is, people who have learnt to sign from deaf parents—need to be employed throughout the process not only as teachers but also as facilitators. The child then has the added value of support from the international deaf community.
Rather than a rush to technology, we need an evidence-based approach to a communications choice for deaf children. The "oral approach"—speaking to the child without signing and expecting spoken language in response—has persisted since it was introduced at the end of the 19th century. This approach can leave deaf children with language skills between 8 and 10 years behind their hearing peers (Susan Gregory, Juliet Bishop and Lesley Sheldon, Deaf Young People—Developing Understanding, Cambridge University Press, 1995). The "total communication" philosophy uses spoken language with signed key words, gesture and facial expression. But as the child cannot hear, the information it receives is sparse.
Cost should not be a bar to the bilingual approach. In Britain, cochlear implants cost between £30 000 and £38 000 per child. What deaf child wouldn't benefit from resources on this scale? It is enough to provide the services of a deaf adult two or three times a week to help the rest of the family to learn signing, followed by timely support with reading and writing after the child has reached school age.
Cochlear implants may be an expensive white elephant, pushed forward by the drive for normalisation through technical innovation in medicine. However, the day of reckoning is coming when our young implant users will be able to show us whether using them with young deaf children does more good than harm. After all, what other socio-educational issue is tackled by surgery?
Marion Beard
Marion Beard is a speech and language therapist who works with deaf people
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