HLAA Convention 2011 Special: Workshops - Auditory Rehabilitation

[Guest guest]

NVRC News - June 27, 2011

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New Options in Auditory Rehabilitation

By Cheryl Heppner 6/27/11

Dr. Niparko wears many hats at s Hopkins Medical - or should that

we say he wears many surgical masks or coats? He is the Interim Director of

the Department of Otolaryngology-Head and Neck Surgery and T. Nager

Professor, as well as Director of the Division of Otology, Audiology,

Neurotology, and Skull Base Surgery, and Director of the Listening Center.

Long-time attendees of NVRC's educational programs will remember his

highly-acclaimed workshops at NVRC in past years.

Every new presentation by Dr. Niparko brings exciting information, and his

workshop " New Options in Auditory Rehabilition " on Friday, June 17, 2011 at

the convention was no exception.

Setting the backdrop for his program, Dr. Niparko emphasized the importance

of the spoken word, which connects us to one another and maximizes our

communication. He called the importance of the cochlea to our hearing akin

to flipping a switch to turn on a light fixture. The hair cells in the

cochlea are some of the body's smartest cells, and they have a very complex

structure. Atop them are tufts of cilia; if they fail to beat, or fall off,

or die, we get hearing loss.

The importance of speech sounds

There are 45 different sounds in English spoken by a native speaker. Each

has its own sound signature. That sound signature is very different in a

non-native speaker. The brain learns these sounds from the time you are

born. The sounds have three dimension - intensity which comes from loudness

of the speech, frequency which comes from pitch, and timing which is

determined by the onset and duration of the speech. There are regional

differences and dialects. As an example, people from the Midwest hold their

vowels longer.

Dr. Niparko quipped that the 45 speech sounds for male listeners have a hole

for the spouse's voice, and this is a problem he can't solve.

We tend to tail off frequency at the end of a word. A change in frequency

information aids in localization, which is the ability of our ears to zone

in and choose the voice of the person we want to listen to. When there are

multiple speakers, we zone in with their specific pitch cues.

The effect of hearing loss

The effect of aging on hearing is one of the things we can do the least

about. Hair cells are fragile, particularly for men. A 60 year old male

will typically have much higher hearing loss than a female of the same age.

Trauma is another cause of hearing loss. It could come from damage due to

noise. We now start to see signs of hearing loss in young adults. An

estimated 8.5% of those aged 20-29 have a hearing loss. In the future there

is hope we can see continued steps to avoid the onset of hearing loss.

Sensorineural hearing loss is almost completely absent on Easter Island.

Here in the U.S., something genetic may be the cause of the higher rate. We

now also know that medications can cause hearing loss and that some people

are more sensitive to the effects of noise than others.

The impact of hearing loss

The symptoms of hearing loss are not just reduced ability to hear. There is

reduced sensitivity to sound and impaired pitch resolution. There can be

loudness recruitment, which causes painful or almost painful surges of

loudness. Tinnitus continues to be an issue, although advances which can

mask or suppress it have helped. Some individuals were helped by putting

sound that is just below the level of the tinnitus in the ear, such as

music.

Understanding speech in noise is a great problem in sensorineural hearing

loss. With this form of hearing loss, the ear is being swamped by noise and

recruitment. Speech is remarkably resistant to corruption. We are born

with the ability to use it well, but it can be difficult or impossible to

understand speech when there are multiple speakers, especially in a large

room where sound is being reflected from hard surfaces. These are factors

that modify the pitch and timing structure of the speech signals and create

a masking effect.

Perceptions about hearing rehabilitation have been varied. A recent

MarkeTrak survey found that seniors with hearing loss often reported " I hear

well enough and don't mind it, " thus marginalizing themselves. As a result,

they often tend to adopt a less communication-filled lifestyle and reduce

their social connections. Sensorineural hearing loss has long been

associated with social withdrawal, which frequently brings consequences such

as decreased general health and impaired immunity.

Recent research has also shown that hearing loss could be associated with

increased risk of dementia. With severe hearing loss, an individual's

chance of getting clinically significant dementia is 70% if left untreated.

Getting a cochlear implant can significantly mitigate the effect, and use of

hearing aids on a consistent basis also helps. It is essential that we

bring hearing aids and cochlear implants into the treatment picture.

Current predictions show that the percent of people with dementia will

double in 20 years, and by 2050 it could affect 1 in 30 Americans.

New advances

Newer hearing aids are a step in the right direction. They look better, are

more comfortable, and more of them are able to provide directionality

(ability to identify direction of sound) and provide noise reduction. They

also increase the naturalness of speech and its fidelity. But they still

are not the same as normal hearing and require adjustment.

Cochlear implant electrodes in the inner ear stimulate the auditory nerve

through responsiveness to electrical signals. Modern digital technology has

helped us to increase the speed of sound processing; in the early years

cochlear implant users said sound had a robotic or cartoonish quality.

We have now been able to achieve preservation of healthy hair cells in the

ear and stimulate the rest of the cochlea with a cochlear implant. It is

possible to wear a hearing aid in the same ear and preserve hearing while

getting a more natural sound. This has worked very well for selective

patients.

Questions and answers

Q: Which comes first, the hearing loss or dementia?

Dr. Niparko: Someone could have reduced speech understanding due to

dementia, but data in many cases showed that hearing loss preceded the

dementia. Data is also beginning to show us the importance of social

connections.

Q: If someone is already exhibiting symptoms of dementia, is it too late

for a cochlear implant?

A: Based on data we have now, a hearing aid is probably much more helpful.

Q: What are the experiences of cochlear implant users who have had

chemotherapy?

A: Several patients went through chemotherapy with a cochlear implant in

place. The implant may not be stable in many cases due to the neurotoxic

effect chemotherapy can have on nerves, but it hasn't seemed to have a

permanent effect.

Q: How good are the results with partial insertion implants?

A: A lot of music comes into the ear through the low tones, which helps

pick up the beat/rhythm and bass. Research is still open on this. Some

people with the partial implants were not happy and came back to get

implants with full insertion. One individual has done well. This person

had hearing loss that started in high school and got an implant 30 years

later. Hear hearing aids in both ears are supplemented with a cochlear

implant. She calls it " trimodal hearing " .

Q: What about auditory neuropathy?

A: We are seeing this more frequently. It is a result of the brain

mechanisms not putting information together well.

Q: What are the primary predictors of a cochlear implant?

A: An auditory foundation.

Q: What resources are there to help learn speech understanding with a

cochlear implant?

A: All of the cochlear implant companies have online resources, and there

is a web product called LACE.

Q: What will be the impact on bilateral cochlear implants if I have carotid

surgery?

A: Today the only concern about surgery is if it involves the head, not the

neck or anything below it.

Q: What cochlear implants make it possible to have MRIs?

A: We now have a way to perform MRIs on patients who have cochlear implants

without having to remove the magnet. A binding procedure is used. The

important thing to know Is that we can do the scan but we can't keep you

comfortable. It will hurt for about 10 minutes afterward because the

magnets are moving around. We couldn't find an MRI with a Tesla

(measurement of strength) of less than 1.0, so the research has used one

with a Tesla of 1.5.

Dr. Niparko showed a short video from his famous 2005 study with Ryugo

where deaf cats were implanted for three months with a 6-channel cochlear

implant that used human speech processing programs. The cats responded to

environmental sounds and their auditory nerve fibers showed some recovery.

Food conditioning was used, and the cats could differentiate the sound of

music by Bach from the sound of music by Beethoven.

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