|
E-mail this page to a friend!
Aging News & Information
Hardest-of-Hearing Senior Citizens May Some Day Hear
with Auditory Nerve Implant
Appears to offer superior alternative to cochlear
implants in U-M animal study
| |
 |
|
| |
Hearing through an cochlear implant may
sound different from normal hearing, but it lets many people
communicate orally in person and over the telephone, and
perceive sounds in the environment. Click photo for larger view. |
|
June 18, 2007 Hearing loss is one of the most
common ailments suffered by senior citizens almost half of those over
75 have hearing loss. Hearing aids help many and, for severe cases, the
cochlear implants provide a partial solution. Now, however, scientists
have shown in animals that its possible to implant a tiny, ultra-thin
electrode array in the auditory nerve that can successfully transmit a
wide range of sounds to the brain.
(Read more about senior citizens and hearing loss
below this article.)
More than three decades ago, scientists pursued the
then-radical idea of implanting tiny electronic hearing devices in the
inner ear to help profoundly deaf people. An even bolder alternative
that promised superior results - implanting a device directly in the
auditory nerve - was set aside as too difficult, given the technology of
the day.
Scientists at the University of Michigan Kresge
Hearing Research Institute think they may have found the solution.
If the idea pans out in further animal and human
studies, profoundly and severely deaf people would have another option
that could allow them to hear low-pitched sounds common in speech,
converse in a noisy room, identify high and low voices, and appreciate
music areas where cochlear implants, though a boon, have significant
limitations.
In nearly every measure, these work better than
cochlear implants, says U-M researcher John C. Middlebrooks.
| |
Read more about
senior citizens and hearing loss below this article. |
|
He led a study requested by the National Institutes
of Health to re-evaluate the potential of auditory nerve implants.
Middlebrooks is a U-M Medical School professor of otolaryngology and
biomedical engineering. He collaborated with Russell L. Snyder of the
University of California, San Francisco and Utah State University. The
two co-authored an article on the results in the June issue of Journal
of the Association for Research in Otolaryngology.
The possible auditory nerve implants likely would
be suitable for the same people who are candidates today for cochlear
implants: the profoundly deaf, who cant hear at all, and the severely
deaf, whose hearing ability is greatly reduced. Also, the animal studies
suggest that implantation of the devices has little impact on normal
hearing, offering the possibility of restoring sensitivity to high
frequencies while preserving remaining low-frequency hearing.
Middlebrooks says its possible that the low power
requirements of the auditory nerve implants might lead to development of
totally implantable devices. That would be an improvement over the
external speech processor and battery pack cochlear implant users need
to wear and often have to recharge daily.
If the initial success in animals is borne out in
further tests, a human auditory nerve implant is probably five to 10
years away, he says.
The researchers used cats bred for laboratory use
in their experiments. They measured brain processing of auditory signals
in normal conditions, then compared deaf animals brain responses to
sounds using cochlear implants and then the direct auditory nerve
implants. These measurements employed neuron -monitoring technology
developed earlier at U-M.
The scientists found their sensitive 16-electrode
microarray resulted in several advantages over cochlear implants.
Approved by the Food and Drug Administration in
1984, cochlear implants have greatly benefited profoundly and severely
deaf people. More than 100,000 implants have been performed worldwide in
the last two decades, including more than 1,000 at U-M.
Like the new device, cochlear implants are small
electrode arrays that receive signals from an external sound processor.
They are designed to stimulate the auditory nerve and other cells to
produce a sensation of hearing. But their location, separated from
auditory nerve fibers by fluid and a bony wall, is a limitation.
Access to specific nerve fibers is blunted,
Middlebrooks says. The effect is rather like talking to someone through
a closed door.
With the new intraneural stimulation procedure,
that effect is eliminated, and there are other technical advantages,
too.
The intimate contact of the array with the nerve
fibers achieves more precise activation of fibers signaling specific
frequencies, reduced electrical current requirements and dramatically
reduced interference among electrodes when they are stimulated
simultaneously, Middlebrooks says.
Middlebrooks has talked with U-M surgeons in
otolaryngology about surgical approaches in humans, and is working with
U-M biomedical engineers on an intraneural device that can remain in
place and be tested further in animals over the next two years. The
devices need to be studied over time to see if they are safely tolerated
by the auditory nerve.
If our work continues to go very well, we might
begin human trials in no less than five years, Middleton says.
Such a device might be used first in people whose
cochleas are filled with bone and therefore arent eligible for a
cochlear implant, or people whose cochlear implants are no longer
effective.
The University of Michigan has submitted a patent
application for the procedure. Through its Office of Technology
Transfer, it is seeking a commercialization partner to assist in
bringing the technology to market.
Editors Notes:
Funding for the study came from the National
Institute on Deafness and Other Communication Disorders, National
Institutes of Health.
Journal citation: Auditory Prosthesis with a
Penetrating Nerve Array, Journal of the Association for Research in
Otolaryngology, Volume 8, Number 2 / June, 2007;
10.1007/s10162-007-0070-2 (DOI)
Original article written by: Anne Rueter
University of Michigan Kresge Hearing Research Institute
U-M Medical School
More Information About Senior
Citizens and Hearing Loss
Hearing loss is one of the most common conditions
affecting older adults and it is the most common in men. Roughly
one-third of Americans 65 to 74 years of age and 47 percent of those 75
and older have hearing loss.
Approximately 28 million
Americans have a hearing impairment.
There are two general categories of hearing loss.
● Sensorineural hearing loss occurs when there is
damage to the inner ear or the auditory nerve. This type of hearing loss
is permanent.
● Conductive hearing loss occurs when sound waves
cannot reach the inner ear. The cause may be earwax build-up, fluid, or
a punctured eardrum. Medical or surgical treatment can usually restore
conductive hearing loss.
Presbycusis, one form of hearing loss, comes on
gradually as a person ages.
Presbycusis can occur because of changes in the
inner ear, auditory nerve, middle ear, or outer ear. Some of its causes
are aging, loud noise, heredity, head injury, infection, illness,
certain prescription drugs, and circulation problems such as high blood
pressure.
Presbycusis commonly affects people over 50, many
of whom are likely to lose some hearing each year. Having presbycusis
may make it hard for a person to tolerate loud sounds or to hear what
others are saying.
Doctors do not know why presbycusis happens, but it
seems to run in families.
Tinnitus, also common in older people, is the
ringing, hissing, or roaring sound in the ears frequently caused by
exposure to loud noise or certain medicines.
Almost 12 percent of men who are 65 to
74 years of age are affected by tinnitus.Tinnitus is a symptom,
not a disease, so it can accompany any type of hearing loss.
Tinnitus can also be a sign of other important
health problems, such as allergies and problems in the heart and blood
vessels. Tinnitus can come and go, or it can persist or stop altogether.
Some people may not want to admit they have trouble
hearing. Older people who can't hear well may become depressed or
withdraw from others to avoid feeling frustrated or embarrassed about
not understanding what is being said. It is easy to mistakenly call
older people confused, unresponsive, or uncooperative just because they
don't hear well.
Many people who have a hearing loss wear a hearing
aid. A hearing aid is an electronic, battery-operated device that makes
sounds louder to the wearer. Unfortunately, only 20 percent of people
who could benefit from a hearing aid actually wear one.
Hearing aids can be analog or digital. Some analog
aids are custom-built to meet a person's hearing needs. More advanced
analog models can be adjusted with a computer to suit a number of
environments, such as a room with a lot of background noise.
Digital hearing aids use a computer chip to process
sounds, and are the most flexible in adjusting to different
environments. They are also the most expensive.
An audiologist can help you determine if a hearing
aid, or even two hearing aids, is the right treatment for you. Wearing
two hearing aids may help balance sounds, improve your understanding of
words in noisy situations, and make it easier to locate the source of
sounds.
If your hearing loss is severe and of a certain
type, your doctor may suggest that you talk to an otolaryngologist -- a
surgeon who specializes in ear, nose, and throat diseases -- about a
cochlear implant.
Approximately
59,000 people worldwide have received cochlear implants. About 250,000
people would be good candidates for a cochlear implant. In the United
States, about 13,000 adults and nearly 10,000 children have cochlear
implants.
A cochlear implant is a small electronic device
that the surgeon places under the skin and behind the ear. The device
picks up sounds, changes them to electrical signals, and sends them past
the non-working part of the inner ear and on to the brain.
A cochlear implant does not restore or create
normal hearing. Instead, it can help people who are deaf or who have a
severe hearing loss be more aware of their surroundings and understand
speech, sometimes well enough to use the telephone.
But learning to interpret sounds from the implant
takes time and practice. A speech-language pathologist and audiologist
can help you with this part of the process.
What causes hearing loss? Some
possibilities are
● Aging
● Heredity
● Diseases such as
ear infections and
meningitis
● Trauma
● Certain medicines
● Long-term exposure to loud
noise
More information:
●
Hearing Loss at Special Senior Citizen Site by National Institutes of
Health
●
Hearing Loss and Older Adults (National
Institute on Deafness and Other Communication Disorders)
Also available in
Spanish
●
Presbycusis(National
Institute on Deafness and Other Communication Disorders)
Also available in
Spanish
●
Sound Advice about Age--Related Hearing Loss(Food
and Drug Administration)
Click to More Senior News on the
Front Page
Copyright: SeniorJournal.com |
