First Published: April 2000
Last Revised: April 2000
Peer Review Status: Internally Peer Reviewed

What are options other than a cochlear implant?

For patients that are profoundly deaf, the only other option is sign language.

What are the percentages of children born with hearing problems?

We believe there are 28,000,000 in the U.S. that have hearing problems and approximately 1 in 1,000 children are born profoundly deaf.

Is there any other procedure that can be done to insure good hearing in a baby?

The best way is to have the child tested at birth to determine if there are any hearing problems. This can be done while the child is in the hospital. There are two different strategies. One is to do what is called a brain stem auditory response and the other way is to measure the oto acoustic emissions. These tests are screening tests and if the child passes these, there is a good chance that the child will have normal hearing. But if there is a family history of hearing loss in the family, repeated testing should be done at least once a year to make sure that the child does not lose hearing after birth, which does occur.

I understand there are two schools of thought on the cochlear implant. What are these positions?

There is a group of people who believe that cochlear implants should not be given to young children and that these children should grow up with manual communication or sign language. There are problems with that school of thought. Many of us believe that children that are born deaf should be given the opportunity to hear sound and learn language and speech through hearing. Those two schools are the major two differences. One of the problems with the child that speaks with manual language or American Sign Language is that there is no correlation between American Sign Language and reading. Children that do not use sign English or other signs that will teach reading do not develop a fourth grade reading level. Of the children that are brought up with American Sign Language, only 14-18 percent achieve 4th grade reading levels. Our cochlear implant project at the University of Iowa has recently evaluated 58 children who have used the cochlear implant for at least 5 years. All children that are 9 years old or above that have used the device for 5 years, 100 percent of them achieved the 4th grade reading level and most of the children are achieving grade equivalent levels in language.

What has been your most profound experience when installing an implant in a child?

The most profound experience is to see the children 3 or 4 years after they have been implanted and listen to their speech and their ability to communicate. It is very rewarding.

What is the success rate of the cochlear implant, and what is considered a success?

Almost all people that have received the cochlear implant achieve sound awareness and most people are able to understand some speech. About one-half of our adults who have learned language and lost their hearing, this is called post lingual deafness, are able to talk on the telephone in an interactive conversation. Many of our children that are congenitally deaf can also interact on the telephone after they have had their device for several years.

How effective is the implant in allowing a child to hear at normal levels?

That is very easy in that the device can be set, and the child can hear at normal speech levels at 30 or 40 decibels which is normal conversational speech.

Do you think your new clinic will help you in furthering your research on cochlear implants, and if so in what way?

Well, we just moved into a new Institute, Otolaryngology head and neck institute, and this has provided space for our cochlear implant team to be involved in direct patient care. We anticipate that this will be able to expand our services to the hearing impaired and will provide opportunity for development of new strategies and testing materials.

What is the leading company producing the implants at this time?

There are two major companies. One is in Australia and the other in the U.S. The U.S. is Advanced Bionics and the implant that they produce is the Clarion implant. A corporation in the U.S. called the Cochlear Corporation manufactures the implant made in Australia. Their device is called the CI 24. ThereÕs also a device made in Austria called the Medel device. These three devices are multi-channeled in that they can stimulate different areas within the cochlear and produce more realistic speech information.

What symptoms are there for a child who is having troubles with hearing at infancy?

The parents will most likely notice that the child will not babble or make sounds and may not respond to loud sounds. Normal children will reflexively respond to a loud sound, they sort of startle. Children that are profoundly deaf will not respond.

How long do these implants last?

The devices have been developed to last at least 70 years and most of the devices are very stable, and we are not having much problem with failure at this time. If there is a problem with an implant, the device can be removed and replaced without any loss of function.

Who is a candidate for a cochlear implant?

In children, if the hearing aid is not providing a progression in speech or language development and the child cannot repeat words or sentences, then they would be a candidate for a cochlear implant. In adults, these devices are most effective in the post-lingual deafened adult. If a person does not understand 40 percent of sentence material with an appropriate hearing aid or 50 percent in the other ear, then that person would be a candidate for an implant. We usually test word understanding with single words and that is called speech discrimination testing. If someone understands less than 20 percent of single words, that person would be a candidate for a cochlear implant.

How does the cochlear implant work exactly?

In normal hearing individuals, sound is picked up and transferred to the inner ear in a fluid motion. The inner ear then contains hair cells that respond to the fluid movement and then generate an electrical impulse that goes to the brain. In people that are deaf, the problem is not in the nerve, but in the hair cells, the hair cells don't function as they have lost their transducer function of changing a fluid movement into an electrical signal. People that are deaf do not have hair cells. The cochlear implant is a series of electrodes in the inner ear. When sounds are produced it is filtered into different frequency bands , the implant sends information to that region of the inner ear that corresponds to that frequency. The brain accepts that information and is able to interpret that information as speech. These devices take some time to learn to use and like learning a language. The new information coming in is like Russian, and after a period of time it sounds like speech that you remember. So it really depends on the plasticity of the brain.

In relation to age who takes longer to adjust, children or adults?

We know that children, the younger that we implant a child the quicker they learn to use the device and they perform better, if they are implanted at 2 years of age versus 8 years of age. We have determined, however, that children that are implanted at 9 or 10 years of age can learn to use the information and do develop language and reading skills but their speech is not as good as children that have been implanted at 2 years of age. The younger children have almost normal speech.

Of the two strategies to test hearing loss in a newborn which is more effective in detecting hearing problems?

They both are effective. The auditory brain stem response may be a little more accurate that the oto acoustic emissions but are also depends on the person doing the testing. There are several things that can make both of these tests be falsely positive. If there is fluid in the middle ear space at birth, both of these tests are not very accurate. If a child fails one of these screening tests, a physician, usually an ear doctor should look in the ears to determine if there is fluid in the ears and then some measures can be taken to remove the fluid and retest the child.

If there is trauma that causes the deafness can the implants help?

If there has been a trauma that has caused deafness, there may be fibrosis or scarring in the ear or there may be disruption of the hearing nerve from the ear bone to the brain and then this device would not be very effective. In these cases, we would stimulate the nerve or the ear preoperatively by anesthetizing the ear and then through the ear drum place an electrode onto the inner ear to determine if the patient could hear the sound. If they can perceive it as hearing, then the nerve may be okay to implant that patient because they can perceive sound.

Do you ever put the implants in both ears?

We have an FDA study in which we have implanted 10 patients with a device in each ear at the same time. These patients do better in localizing where sound is coming from in a crowded room and they do a little better in a noisy environment compared to a single implant. There have been no problems with implants in both ears and this has only been done in adults.

What is the cost of installing an implant to a young child and to an adult?

The cost for an adult or a child would be the same. The cost of the implant alone is about $25,000 or $26,000. The operating room costs and overnight stay and surgical fee all add up to around $35,000 with the implant. Then some places charge for continued follow up and some add that into the initial fee. This totals somewhere between $35,000 and $40.000, and insurance and Medicare covers it and in most states Medicaid does cover this.

How can you tell if a young child would be appropriate for an implant, say a child one year of age?

In young children that cannot respond to regular testing, there are some new tests that have been developed that can actually determine the level of hearing at each frequency. This is called Steady State Evoked Potential test (SSEP). This was developed in Australia, and we have recently been using this new testing strategy. We feel that we can accurately predict the hearing level at different frequencies in people who have profound hearing loss. This is an objective test that is very good. We don't have to rely upon the responses of the child, and this will help us determine what the thresholds of hearing are at the different frequencies in young children. It will also help us to fit hearing aids in young children.

If a child has a severe hearing loss, when should they get a hearing aid?

Whenever a hearing loss is identified, the child should be fitted with a hearing aid as soon as possible. There are some studies at the University of Colorado that state that if a child has not received amplification by six months of age, they will have poorer language skills compared to children amplified before six months of age. So it is very important to identify hearing loss in young children early and to get hearing aids on them at 1 or 2 months of age. There is a universal infant hearing screening program being proposed throughout the country, and it is very important that we support that to identify hearing loss as soon as possible and get hearing aids on hearing impaired children. If there speech and language do not advance, they would be candidates for cochlear implants at one year of age.

What is the ideal age to implant a young child?

We believe that a one year old identified as being profoundly deaf would be a very good candidate for a cochlear implant.