You Can Help Find New Treatments and Cures
If you have hearing loss, a balance problem, or facial nerve paralysis, this information is for you. It describes what is known about hearing and balance, and problems related to each. It also introduces you to a medical research organization seeking new knowledge about these problems. And it shows you how you can help find new treatments and cures for ear problems by donating your temporal bones to scientific research.
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Inside the Ear:
Still a Mystery
Millions of people are affected by hearing loss and other ear problems. Research into the causes of these problems is difficult. That’s because our hearing and balance organs are found deep within the skull, hidden and protected inside the temporal bones. For researchers trying to learn about ear problems, it is not easy to examine these hidden organs directly in living people. So, studying donated temporal bones after death is one of the best ways to learn about the causes of ear disorders, and to devise new treatments and cures.
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What Is the NIDCD National Temporal Bone Registry?
A program of the National Institute on Deafness and Other Communication Disorders (NIDCD) of the National Institutes of Health, the NIDCD National Temporal Bone, Hearing and Balance Pathology Resource Registry is a nonprofit organization established to provide information about temporal bone donation and research. The Registry also enlists people with ear disorders to be donors of their temporal bones after their death. The Registry arranges for the donations, keeps records, and sends out information about scientific findings from temporal bone research. |
Millions of People Have a Hearing or Balance Disorder
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One of every 10 Americans has some degree of hearing loss.
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By age 65, 1 of every 3 persons experiences some hearing loss. After age 75, this rises to 1 out of every 2 persons.
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An estimated 12.5 million Americans over age 65 have dizziness that significantly interferes with their lives.
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At least 12 million Americans have tinnitus (tin-NI-tus). They hear a ringing, hissing, or buzzing in their ears when there is no external sound.
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About two to three out of every 1,000 children in the United States are born deaf or hard-of-hearing. Still others develop hearing problems during childhood.
An estimated 615,000 individuals have been diagnosed with Meniere’s (Men-YEARZS) disease in the United States. Its symptoms include attacks of dizziness, tinnitus, and hearing loss that comes and goes.
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Looking Inside
the Ear
The outer ear collects sound vibrations and funnels them into the middle ear. These vibrations are then conducted by the middle ear to the fluid-filled inner ear. There, thousands of hair cells change the mechanical energy of the sound waves into electrical impulses that the brain “hears” as sound.
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The Protective
Temporal Bone
The temporal bones form a part of the base of  your skull. They are among the hardest of all your bones, enclosing the tiny organs of your hearing and balance systems. The facial nerve, responsible for control of your facial muscles, takes a long, winding course through the temporal bone from your brain to your face.
............This portion of
.............the temporal bone is studied.
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Click on the image below for a closer look
Types of Hearing Loss and Other Ear Problems
Anyone can have an ear problem that causes hearing loss. Some people are born with a hearing impairment. For others, hearing loss results from a head injury, ear infection, or exposure to loud noise. Often, hearing loss is a part of growing older. Whatever the cause, hearing losses fall into twp broad groups. A loss caused by problems in the outer or middle ears is called a conductive (con-DUK-tiv) hearing loss. A loss resulting from problems in the inner ear or the auditory nerve is known as a sensorineural (sens-so-ree-NU-ral) hearing loss.
Conductive Hearing Loss
When sound waves are blocked anywhere along the path from the outer ear to the inner ear, you experience conductive hearing loss. Conductive loss can be caused by a buildup of wax in the ear canal, a punctured eardrum, a middle ear infection, or malfunction of the ossicles. Conductive loss can often be corrected with medication, surgery, or a hearing aid.
Sensorineural Hearing Loss (Nerve Deafness)
Sensorineural loss can be caused by anything that damages the delicate parts of the inner ear, the auditory nerve, or the brain stem. Damage can be caused by a severe infection such as mumps or German measles, a head injury, certain drugs, an abnormal growth in the ear, a very loud noise, or even by growing older. A hearing aid can often help a person who has sensorineural hearing loss. However, little can be done today to reverse this type of hearing loss.
| Balance disorders occur when the delicate vestibular system is damaged. Information about motion of the head and body may not be sent to the brain properly. The result can be loss of balance, dizziness, and the spinning sensation of vertigo. Sometimes these problems resolve on their own over time. Treatments can help some people with balance disorders, but for many there is currently no helpful therapy. |
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Nerve
impulses
signaling
head move-
ment are
not sent to
the brain properly. |
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| Central auditory and vestibular disorders occur when the brain does not understand the nerve signals for sound and balance. These problems usually involve the brain stem, where some of the brain pathways for hearing and balance are located. |
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Nerve
impulses
from the
inner ear
are not properly interpreted by the
brain. |
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| Facial nerve disorders can happen when a problem affects the nerve within the temporal bone. This can occur because the facial nerve runs through the temporal bone on its way from the brain stem out to the face. Damage to the facial nerve often results in paralysis of the muscles on that side of the face, causing a droopy facial appearance. |
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Facial
paralysis
can be
caused by
damage to
the facial
nerve within
the temporal
bone. |
Studying the Temporal Bone
Thanks to those who contributed their temporal bones in the past, many advances in understanding and treating ear disorders have been made. But there are many other disorders that we need to learn more about. Those living today who agree to donate their temporal bones after death can still make a great contribution. The research they make possible will provide millions with the gift of hearing in the future.
How the Temporal Bone Is Studied
Researchers study both a donor’s temporal bone and medical records. A small part of the temporal bone (only the part containing the middle and inner ears) is surgically removed soon after death. This does not affect the appearance of the donor’s outer ear, face, or head.
The structures of the inner ear can then be prepared for a variety of research techniques, including microscopic study and procedures that allow identification of hearing defects at a molecular level (“molecular biology”).
Researchers examine each sample to learn more about the ear structure and the cause of the donor’s ear problem. With this knowledge, researchers can develop new ways to diagnose and correct ear disorders in others.
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Benefits of Temporal Bone Research
By studying temporal bones from donors with normal hearing and balance, as well as donors with ear disease, researchers have gained new knowledge about hearing, balance and facial nerve problems, and have developed effective new medical and surgical treatments. Here are just a few examples:
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Hearing Loss Due to Aging
Research scientists have found that as we age, we lose the sensory hair cells and other structures within the cochlea of the inner ear. This leads to a type of hearing loss called presbycusis (pres-bee-KU-sis). By studying temporal bone samples, they have discovered that there are actually four major types of presbycusis. With this information, auditory specialists can now better advise you about the hearing aid
that will best meet your needs.
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Benign Positional Vertigo (BPV)
In people suffering from this common disorder, dizziness occurs in certain head positions. Using temporal bones donated by people with BPV, researchers found the cause to be located in one of the three semicircular canals. With this information, health care professionals have been able to develop effective physical exercise and surgical procedures to relieve the problem.
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Otosclerosis
In a condition called otosclerosis
(o-tow-skler-osis), spongy bone tissue grows around one of the tiny bones of the middle ear (the stapes bone) and prevents it from moving. Temporal bone research has shown how this condition can cause both conductive and sensorineural hearing loss. This research has also led to a better understanding of stapedectomy,
a surgical procedure used to treat individuals with otosclerosis.
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Meniere’s Disease
People with Meniere’s disease suffer from bouts of dizziness, ringing in the ears, and hearing loss that comes and goes. In studying temporal bones donated by people with Meniere’s disease, researchers found the condition was caused by an increase in the amount of fluid in the inner ear. This knowledge has led to several medical and surgical approaches to relieve the symptoms of this disease.
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Research Project to Obtain DNA from
Buccal (Cheek) Swabs from Temporal Bone Donors
Histopathological studies of temporal bones and related brain structures donated after death by individuals with hearing or balance can provide very valuable information about the causes and mechanisms of these disorders. The utility of such studies can be enhanced even further by combining the histopathological analysis with DNA studies of genes involved in hearing and balance. It has become apparent in the last several years that the functions of hearing and balance are controlled and determined by a large number of genes. Estimates range from 200 to more than 1,000 genes. It is difficult to extract DNA for genetic studies from temporal bones and related brain tissue; the DNA is often fragmented and contaminated during tissue processing. Therefore, it would be very valuable to obtain the DNA from a clean and uncontaminated sample to enhance the value of the temporal bone studies.
Individuals who are currently registered as temporal bone donors or those who are considering temporal bone donation are requested to also donate a sample of their DNA obtained by using sterile buccal (cheek) swabs. Cheek swabs will be sent by mail to donors. They are extremely easy to use – the sterile brush at the end of the swab is rubbed against the inside of the cheek back and forth several times just like a toothbrush. The brush is placed back in the sterile container and a prepaid envelope will be provided to send the brushes back to the Registry in the mail. DNA will be extracted upon arrival at the Registry at the Massachusetts Eye and Ear Infirmary.
There are virtually no risks of using the cheek swabs. The procedure is as simple and painless as brushing one’s teeth.
Each donor’s DNA sample will be coded. Then the DNA sample will be stored in a freezer at -70 degrees Celsius under this code and no DNA or genetic research will be done until the donor’s death. After death when the temporal bones are obtained, the frozen DNA samples will be used only for research purposes, and only to investigate genes involved in hearing and balance. Results of this research may be presented or published for use by the medical or scientific community, but confidentiality of donors will be protected at all times. No identifying information will be made available to other physicians, research, insurance companies, or any other individual or agency, unless specifically requested by the donor prior to death in the form of a written, signed and confirmed release.
Participation in this study is entirely voluntary. A donor may choose not to donate his/her DNA from the cheek swab and instead to only donate the temporal bones and /or related brain structures. A donor may also withdraw from the study in the future by informing the Registry in writing, in which case his/her DNA sample will be destroyed. There will be no cost to any donor for participating in this study.
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