Bilateral Cochlear Implantation: Potential Benefits and Risks

by Cheryl Heppner

Editor: Here's another of Cheryl's outstanding articles reporting on the 2005 SHHH Convention. This one discusses a presentation by Susan B. Waltzman, Ph.D., of the New York University Cochlear Implant Center.

The Northern Virginia Resource Center for Deaf and Hard of Hearing Persons (NVRC) graciously allows you to share this article, and requests only that you credit them if you do so. You can visit NVRC at www.nvrc.org.

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Hearing and Hearing Loss in Two Ears: A Comparison

1. Hearing with both ears - The two primary advantages to having hearing in both ears are better comprehension in noise with the ability to locate the source of sounds, and detecting differences in timing and loudness levels between the two ears

2. Hearing aids in both ears (bilateral hearing aids) - Hearing aids in both ears can improve the ability to "localize" sounds, especially helping us to know how far away the sound is and its movement. This helps us in demanding conversation settings, such as when two speakers are talking. It helps us ignore one speaker by listening to another, and to switch from the conversation of one to the conversation of another.

3. Cochlear implant in one ear, no hearing aid in the other - Using just a cochlear implant doesn't give the same benefit as having hearing aids in both ears.

4. Cochlear implant in one ear, hearing aid in the other - With this combination you are getting two different signals, one acoustic and one electrical. This may reduce the benefits of having two devices if the brain cannot adapt.

The cochlear implant usually provides the more functional ear, and the hearing aid complements it, but that depends on the amount of hearing in the aided ear.

People with both a cochlear implant and hearing aid often say there is no real hearing benefit, but they say it gives them a more 'balanced' feeling.

5. Two cochlear implants (bilateral cochlear implants) - This combination gives similar information in both ears. It may help with understanding speech in noisy settings and determining the direction a sound is coming from.

Sometimes you are guessing which of the ears is the best to implant, and getting two cochlear implants saves you from having to make that decision. Also, if one implant stops working, the second one gives you a backup so you are not without hearing.

One Cochlear Implant or Two?

Subjective reports from adults that Dr. Waltzman contacted showed that almost every adult patient said having two cochlear implants was much better. Yet Dr. Waltzman cautions that there are drawbacks. Among them are:

- When you already have one cochlear implant, you can't expect having the second implant to give the same life-changing experience you had with the first.

- You may benefit from the second one, but it will take time to accomplish that. Usually when those who already have one implant get the second implant turned on, they make comments like "it sounds funny" and "it sounds weird."

- If you get two cochlear implants at the same time, it's a different story. Individuals who did that say when they take one off "this is awful."

If you get a second cochlear implant, surgical risks are lower when both ears are done in the same surgery.

The cost of having a second implant is an issue. Insurance companies often will not pay and you could be faced with a hefty bill. New York University has been lucky in getting theirs covered. But you should be aware that pre-approval by an insurance company doesn't mean the company will pay for the second implant.

Of all the arguments against having a second cochlear implant, probably the weakest is saving the ear for the future, particularly for young children in the early stages of language development. Dr. Waltzman was at first very conservative about bilateral implants, but in the last few months her attitude has changed. NYU found that many parents would come back and ask about doing a second cochlear implant for their children, after seeing their children struggling in the noisy environments at their schools and elsewhere.

Two Now, or One?

Should you choose to do bilateral implants that are sequential (one implant now, one later) or simultaneous (both at the same time)? In making the decision, you need to think carefully about:

- Where am I having trouble?

- What do I want to achieve with the second implant?

You may be asked to try a hearing aid in the second ear first to see if it gives any help.

Surgery is a big step for many parents of infants and young children. Sometimes cochlear implant centers will broach the subject, but parents will have enough difficulty dealing with just having surgery done on one ear. Many will say "let's try just one ear and see how it goes." NYU understands and appreciates this. They will, however, encourage bilateral cochlear implants for children or adults if they have lost their hearing from meningitis; in waiting you may increase the risk that the second ear can't be done.

Other Factors to Consider

Age is also a factor in making the decision to have two cochlear implants. For adults aged 40-60 who have had profound hearing loss since birth, Dr. Waltzman said she would be conservative about recommending them.

Dr. Waltzman said there are too many disappointed people with cochlear implants because they set their expectations too high. You will have greater access to sound with a cochlear implant, but how much your brain can make use of it is another story.

You'll also need to think carefully about programming options. It can be very complex to program two implants, and you need to be able to go to a place that really understands how to do it. Dr. Waltzman sees a lot of people who are not doing as well as they should because their cochlear implant is not programmed correctly. Other times, she sees people who hope for more, but finds their programming is as good as it gets.

Everyone in one study of people with a second cochlear implant was found to be better at knowing the direction of sound, but tests don't show that there is a benefit in improved speech understanding. People are still working to devise better tests to measure just how well the second cochlear implant works.

Be very aware that if you have had one cochlear implant for some length of time, arrays and processors have changed. Some older devices aren't even manufactured any longer. This may mean that you will have to adjust to the second cochlear implant just as you did the first. Dr. Waltzman spoke about a child who was implanted at age two. The implant failed when the child was a teenager. When a new cochlear implant was re-implanted and turned on, the teenager said the sound was like someone talking in Japanese, and it was frustrating to work and wait for the brain to adjust.

The Evaluation Process

The evaluation process for bilateral cochlear implant surgery involves a medical history, audiology tests, localization tests, speech perception tests (quiet, noise), medical tests, otology tests, radiology tests, and vestibular tests. There is also counseling about appropriate expectations.

Questions and Answers

Q: I am 86 and I have had hearing loss in both ears for 60 years; severe in one, profound in the other. I benefit from a hearing aid in one ear. Are cochlear implants an option for me?

A: People as old as 92 have been implanted. You must be in good health and able to undergo anesthesia.

Q: I have profound/severe hearing loss, hear well with a cochlear implant, but find that at work I can't hear people who come from one side. I have had the cochlear implant for two years and wear a hearing aid in the other ear, but it isn't giving much help. What do you recommend?

A: I recommend asking for the loan of another hearing aid intended to help with your range of hearing loss for a month to see if it helps; if not, consider a second cochlear implant.