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May 4, 2006

Advances in cochlear implants

From: Basque Research - Usurbil,Spain - May 4, 2006

Advances in cochlear implants

About one in a thousand children are born each year with an auditory deficiency that is susceptible to treatment by means of a cochlear implant.

A cochlear implant is an electronic device capable of substituting for the external, middle and inner ear, picking up the sound vibrations, transforming them into electrical stimuli and applying them directly to the auditory nerve in such a way that the brain processes this signal in a meaningful manner.


Bilaterality, importantly, is the stimulation of the auditory canal in both ears and can be artificially achieved by implanting cochlear implants in each ear or, at times, a cochlear implant in one ear and a hearing aid in the other.

Tests are proving that this bilateral implantation has “positive” results in a number of aspects: patients are capable of determining the location of sounds (where they are coming from), can better understand despite background noise and have more spatial auditory perception than those patients with just a single implant. In this manner, persons who otherwise would have unfavourable acoustic conditions, gain access to the spoken word. Bilaterality also avoids the shadow effect whereby if we hear speech from one side and this does not coincide with the sounds picked up by the implant, we do not hear.

Complications, bilingualism and new technologies

Complications occur in 3% of cases, a relatively low figure. It is quite possible that, in the future, we will be able to reduce and even eliminate this figure.

As regards the rehabilitation techniques of implanted patients, bilingualism and the stimulation of auditory memory are considered principally. Current reality in Spain is that, in a number of Autonomous Communities, more than one spoken language is used, both at school and in the family home. This is why there was some doubt about whether a child implanted with a cochlear implant could access a second language: the results tell us that it is indeed possible, depending if the implant has been fitted at an early age (in the first two years of life there is greater access to bilingualism), depending on the family ambience and on the rehabilitation techniques used by the speech therapists and in the school. If used appropriately, even more than two languages can be accessed.

Application of new technologies to cochlear implants has taken place over recent years. The electrodes we use are increasingly non-aggressive, we have stimulation strategies that are quicker and more capable of simulating the spoken word or music more closely to the real thing and, in the technological sphere, we also have systems that enable us, not only to stimulate the auditory system, but also to gather information by telemetric procedures as with this system (for stimulating and diagnosing). This is highly useful subsequently for programming the cochlear implant in the manner most appropriate to the needs of the individual person.

Very few side effects

In reality, any person with a severe-profound auditory deficiency is suitable for this treatment. In fact, initially only totally deaf persons were selected for the treatment but, currently, patients who have residual hearing are being fitted with implants. Likewise, the implant is suitable for any child born with a profound loss of hearing. The operation, which lasts no more than 90 minutes, can be carried out six months after birth.

There have been other side effects that have been overcome such as patients with malformation of the cochclea and patients with problems associated with hearing loss conditions, such as Downe’s Syndrome, deafness and blindness condition, autism or cerebral paralysis. These are persons who we have seen benefit from cochlear implants and, although requiring more work and effort, the technique is totally viable. The same applies to the elderly: The oldest person la fitted with an implant at the University Hospital is 84 years old.

The future

Cochlear implants are on the way to being systems for acoustic signal enhancement that further improve hearing and that are totally implantable in the body. They not only stimulate the auditory canal but will also preserve and maintain the best possible conditions. In this way, by using implants that maintain the auditory canal in the best possible conditions, medication will no longer be needed.

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