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Adoración Júarez Sánchez
Entender y hablar
C/ Pez Austral, 15
28007 Madrid
Tél. 00.34.91.57.47.67.1

1. Introduction

Throughout the 20 th century new technology has made it possible to develop various tools which are capable of adjusting hearing impairments: the linear amplification model used by conventional prostheses – even if it is useful to the child with deeply impaired hearing– is mainly adapted to moderate or 1^st group severe impairments.

In the case of profound impairment, the cochlear implant has brought significant qualitative changes: for the first time, it has become possible for a child born with a hearing impairment to develop functional – and I want to insist on the word functional - hearing.

2.1 : Codifying: conventional prostheses amplify sound in a linear fashion, whereas the main characteristic of a neuro-sensory hearing impairment is the frequency variability of the hearing loss which results in inaccurate functioning of the cochlea whose role is to codify the acoustic information before transmitting it to the brain.

The implant is not an amplifier, but a codifier meant to work like a cochlea. The essential difference is that the information provided by the implant is limited but its structure is representative of the original sound.

2.2. Learning and brain plasticity: The implant does not provide the child with normal hearing, nor it is available by the 24th week of intra-uterine life as is the case for a child with normal hearing. In order to make the best use of the implant, it is necessary to go through a process of conditioning and learning, which seeks to help the child’s brain to do what it would naturally do if the child had no hearing impairment, namely giving meaning to sounds and at the same time building up perceptive models.

A young child with a hearing impairment still has this cerebral potential, but it is subject to the advantages and limits of cerebral plasticity: a very young brain is able to adjust to the characteristics of sensory inputs, even if they do not fit a standard model, but it is only able to do so for a few years and provided the sensorial path is given early stimulation.

2.3. Language acquisition and hearing impairment: Until now, our efforts to help a child with profound hearing impairment acquire oral language (with developmental characteristics which follow an ontological mode, in order to be heard) were based on providing additional information such as visual information: lip-reading, sign-language, cued-speech, written language.

This change in sensory paths bears some complex implications for the development of abilities such as attention or cognitive and linguistic processing of verbal messages.

One well-known consequence of this phenomenon is that the results of our language stimulation methods on children with a hearing impairment were highly dependent on their level of intelligence, the quality of their behaviour and the intensity of the specialised therapeutic programme.

2.4. Functional hearing: It is extremely important to distinguish normal hearing from functional hearing, particularly since the development of implants may create false hopes, mainly in parents.

Functional hearing is the ability to identify, through the auditory channel, verbal messages made of elements which are already known to the child. For example, we can measure this phenomenon through vocal audiometric testing: it is quite common to obtain close to 100 % correct answers on an open-set sentence-repetition test, while tonal audiometry continues to show a very significant hearing loss even with a hearing aid.

The difference mainly lies at the level of learning: even though a child with impaired hearing may develop excellent functional hearing in the long run, the impairment may nevertheless prevent, delay or disturb the natural and automatic acquisition process of new or unknown information.

It is thus essential to explain to both professionals and parents that moving from the real hearing level provided by the implant to functional hearing, which will enable the child to acquire communicative autonomy, implies practising and learning mediating processes.

The cochlear implant is no longer at an experimental stage. Many teams throughout the world already work with pre-speaking hearing impaired children who had implant surgery several years before and whose development has been carefully monitored (see for example the review by Makhdoum et al. 1997 or Nottingham series – Archbold 1999.).

In Spain, Dr Manrique and Dr Huarte’s team in Pampelune have studied the longest series, using the most rigorous methodology (Huarte and Manrique 1999).

The published results bring to light several points:

- A cochlear implant enables a child with deep hearing impairment to build up, after several years, some functional hearing similar to that of a child with type 2 middle hearing impairment or type 1 severe impairment who has been wearing a conventional hearing aid.

- Only children provided with early implant surgery (before the age of 6) can reach this level of functional speech identification

- Results are better and faster if implant surgery occurs before the age of 3.

- The impact of this hearing ability on their expressive speech and language development is very significant.

In the context of early treatment, cochlear implant technology has induced very important changes, although not as radical as supporters of one or the other side of the eternal oralists vs. gestualists conflict tend to believe or make believe. Only describe some of the most significant changes will be described.

3.1. Access to a truly functional oral language has become available to a greater number of children with deep hearing impairment and especially to those who do not have the ability to compensate for the hearing impairment by excellent skills in other areas.

3.2. The decision to chose the implant technique is linked to a methodological choice which will encourage oral communication, but in the author’s opinion, this choice should not be an exclusive option.

The cochlear implant undoubtedly improves the quality of stimulation and practice of hearing and language skills by rendering these situations more natural and functional: the child is not as dependent on visual cues and the games these children can engage in are quite similar to regular games.

Yet it is important to clarify that the implant does not provide the child with normal hearing. If we wish the child to acquire oral language in an easier, quicker and more efficient way, it is still necessary to rely on communicative aids such as cued speech. Furthermore, the child continues to have a hearing impairment, even if he or she wears a more efficient aid: the right to be different remains.

Children and teenagers wearing an implant within the ‘deaf community’ are presently faced with a difficult situation but it is highly possible that some important changes will occur within the community, probably towards greater diversity. It is important to stress that the cochlear implant technique is not incompatible with bilingualism: i.e., oral language / sign language.

As it is the case for hearing children, becoming bilingual may become possible through different strategies, on a simultaneous or successive basis, starting with one language or the other. We only hope that, with the advent of the 21st century, we will understand the need to recognize diversity without exclusion.

4.1. Decision making: implant medical teams are more and more in favour of very early implant surgery; yet, the objective assessment of residual hearing skills continues to lack precision and must be confirmed through behavioural observations.

In the first implant programmes, the situation was relatively clear, since surgery did not occur before the age of 2 or 3. We often had several months to a year to work with the children and their families and were thus able to provide detailed information at multi-disciplinary meetings about the implant.

In addition, during this time, we could provide better training and information to the families.

Today, the process has become faster, with sometimes just a few months between diagnosis and surgery at an age when it is extremely difficult to assess the general skills of a child.

I think we should reach a balance between the need for early implant and the need for an overall assessment of the child.

4.2 Excessive expectations and poor stimulation: Throughout the last few years most of the teams dealing with early education and parental guidance were successful in providing the families with a intensive programme emphasising the need to become not only excellent parents but also excellent communicators, through specific training.

The positive results of implant programmes, coupled with inadequate training in some of the medical fields specialising in the developmental aspects of hearing impairment are likely to endanger these programmes: some parents who observe that their baby is answering to sounds may easily believe that the training processes and intensive stimulation programmes which are proposed to them are useless. This risk is especially present when the implant team which informs the parents is lacking in disciplinary diversity.

4.3 We are also faced with a technical assessment problem: many of our assessment tools were made obsolete by the rapid improvement in functional hearing and in voice and speech quality. We have to strive towards building new measuring techniques which are adapted to very young children with a hearing impairment. In Spain, the first assessment procedure was developed in 1996 by Huarte et al.

In addition, it is not always possible to measure some parameters which nevertheless are an indication of essential qualitative changes in the child’s behaviour: the quality of his attention and the development of hearing skills geared to the alert function, to relating to the outside world, and to taking communicational initiatives …

We try to follow the development of these children through questionnaires and observation sheets (for example, the questionnaire designed for parents, developed in 1998 by Archbold and Lutman).

4.4. The implant is an aid that must be programmed in an individualised way; the programming technique is a little tedious but quite easy to apply to older children, although much more difficult in babies and younger children.

This progressive adjustment process of the programme requires frequent and careful control as well as close collaboration between the technician and the educational therapist or the speech and language therapist in charge of the child: this is precisely where the problems may occur and where we observed significant differences between different teams.

The consumers – namely the parents – must exert strong pressure upon manufacturers and implant teams in order to make sure they obtain optimal and homogeneous care and monitoring for the child.

Throughout the past three years our Centre has specifically focused on those particular cases which most often have been considered unfit for an implant after the first selection procedures. These children with hearing impairment also displayed another impairment such as a visual, motor or intellectual deficit, or a learning disability.

We can understand why these complex cases were excluded during the experimental stage of an implant programme, but we believe that it is no longer justified to exclude them on the basis of their multiple disabilities: in fact, we hold quite the opposite belief.

Within the framework of our initial concepts, we can assume that, for a child with normal hearing, it is not necessary to be particularly intelligent or with good concentration in order to learn how to speak, but for a child with a hearing impairment those qualities are quite crucial.

Children with a hearing impairment and multiple disabilities are precisely lacking in compensatory skills: this is exactly why it is so important to give them some hearing skills.

They obviously will not reach the highest levels of achievement, but children should not be compared to one another; the goal is to compare the level a child may reach through process A and through process B.

This exclusion policy should appear as particularly inappropriate when we know that multiple disabilities are never a contra-indication to conventional aids.

Specialised education should be provided as a condition to an implant decision but this should not be different from the case of a conventional aid: here again, we are confronted with two sets of rules.

Some of those particular cases are presented below: it is quite easy to objectively demonstrate the short-term impact of the implant for some of them (the first two cases) but in other cases progress is much slower or changes occur in areas which are not easy to explore and quantify (the last two cases).

All cases concern children with pre-speaking profound hearing impairment.

First case : E is an immigrant child from Columbia who started attending our facility 3 years ago ; from the beginning, he showed significant behavioural problems and major learning difficulties in spite of normal cognitive potential. He has some specific deficits in sequential organization, which is impairing lip-reading and speech-production in spite of good voice quality.

The acquisition of a sign communication system also appeared to be very difficult and the child did not seem to take a very active part in it.

* IS = Implant surgery

Second case: P. The diagnosis was made at the age of 10 months, hearing aids were adapted at 12 months and the specialised programme was started at 14 months; monolingual option with help in signed Spanish and cued-speech: a diagnosis of oro-facial dyspraxia was made at the age of 2, and he had great difficulty chewing, swallowing, and of course speaking.

Communication and oral comprehension skills showed good progress.

* IS = Implant Surgery

Third case: B. is a premature child with complete blindness in one eye and retinitis in the other, with very poor residual visual skills. The programme was started at the age of 17 months, hearing aids were adapted at the age of 18 months; the child reacted only to very loud sounds and did not develop any prattling. Relational behaviours were very passive: we tried to adapt gesture communication to his sight and hearing impairment but this adaptation did not give the expected results. Implant surgery was carried out at the age of 24 months.

After 6 months, the child responded to familiar noises and to his name and understood through the auditory channel a few words and simple orders within a given context; then he started to shout and emit a few sounds; his communicational behaviour became more active and he started to initiate his first signs.

Fourth case: J: a premature child with spastic cerebral motor impairment; the programme was started at the age of 12 months on the basis of auditory stimulation combined with sign communication; response to sound was very deficient and sign language development was impaired by erratic eye movements and limited motor abilities; it had become impossible for this child to communicate at all. The team considered the possibility of an associated mental disability.

Implant surgery was carried out at the age of 3.

After one year, the parents mentioned that the child was asking for his implant (whereas he would never ask for his previous hearing aids), that he responded to familiar noises and was able to identify some of them. He could emit some vocal sounds in order to attract people’s attention. Signed spontaneous messages became more and more frequent. Some alternative graphic systems will be introduced in the programme in order to help the child become expressive.

Functional hearing is the organising force of speech and language development programmes. The cochlear implant gives an additional opportunity to children with deep hearing impairment to reach a stage where they will be able to develop better personal and social integration skills.

To use ‘profit’ as a criterion for applying this technique is both unfair as a principle and methodologically wrong.

But in spite of this new opportunity we should keep in mind that the ‘deaf community’ has fought for, and obtained, in the last few years recognition of their identity and their right to an educational system which is adapted to their communication needs.

The choice of the implant is obviously linked with a particular way of conceptualizing of these children’s hearing impairment and educational needs, but it should not be considered as incompatible with others options: families have the right to be completely informed - as objectively as possible - before making a decision.

Archbold S. (1999) : Programa pediátrico de implante coclear en Nottingham. Integración. 10 . 6-11

Archbold S. et Lutman M. (1998) : Questionnaire of Nottingham Paediatric Cochlear Implant Programe - Univ. of Southampton.

Huarte A.,Molina M., Manrique M.,Olleta I. et Garcia-Tapia R. (1996) : Protocolo para la valoración de la audición y el lenguaje, en lengua española, en un programa de implantes cocleares. Acta ORL Española. Vol.47.Suplemento 1.

Huarte A. et Manrique H. (1999) : Implantes cocleares en niños prelinguales. In M. Monfort (ed.) : Logopedia, Ciencia y Técnica. Madrid. CEPE.

Makhdoum M.J., Snik F.M. et van den Broek P. (1997) : Cochlear implantation : a review of the litterature and the Nijmegen results. J. Laryng. and Otol. 111. 1008-1017

Pasic T.R. et Rubel E.W. (1989) : Rapid changes in cochlear nucleus cell size following blockage of auditory nerve electrical activity gerbils. J.Comp.Neurol. 283. 474-480