Formula Medical Group
Apple Valley, CA
760-242-1234


James Krider, MD


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Hearing loss - Otosclerosis (ear bone degeneration)

What is ear bone degeneration?

In ear bone degeneration, which is known medically as otosclerosis, the sound-conducting bones of the ear change in composition from hard, mineralized cells to spongy, immature bone tissue.

Early in the disease, these changes are limited to small areas. If the condition progresses, however, much of the bone may become soft and pliable, preventing the stapes or stirrup (one of the tiny bones in the middle ear) from transmitting sound waves. The result is progressive conductive deafness, which occurs because the base of the stirrup becomes fixed to the softened bone structure of the inner ear, making it impossible for sound vibrations to pass from one to the other.

SYMPTOMS

  • Gradual hearing loss starting between the ages of 20 and 40.
  • Evidence that the hearing loss is conductive rather than neural. (People with nerve deafness are unable to hear sounds that produce fine vibrations of the skull bones, which transmit to the auditory nerve.)
  • Hearing loss with a normal eardrum.

Ear bone degeneration affects women more often than men, and it is much more common among whites than among blacks and people of Asian ancestry. An estimated 10 percent of white adults have some ear bone degeneration, but only a small number develop impaired hearing.

What causes ear bone degeneration?

Otosclerosis is an inherited condition, although its precise mode of genetic trans­mission is unclear. The bones that degenerate develop from a single embryonic structure, the otic capsule. The material that replaces mature bone in otosclerosis is similar to the cells that make up the otic capsule during fetal development. Both ears are usually involved.

Gradual hearing loss typically starts in young adulthood.

Gradual hearing loss typically starts in young adulthood.

How is ear bone degeneration diagnosed and treated?

The doctor performs hearing tests to measure the degree of hearing loss and determine whether the problem is conductive (stemming from mechanical problems in the hearing apparatus) or sensorineural (caused by damage to the auditory nerve). Most cases of conductive deafness in adults with normal eardrums are the result of ear bone degeneration.

In selected cases, surgery may correct the problem. When surgery is too risky or unlikely to work, use of a hearing aid may help.

When should I see my doctor?
The hearing loss is so gradual that you may not notice it until it is fairly advanced. To detect hearing loss early, have your ears checked regularly, especially if ear bone degeneration runs in your family.

What can I do myself?
There is no self-treatment for this condition, but you can take measures to detect hearing loss before it becomes an impediment. Take note, for example, if you find yourself misunderstanding others' speech or setting your television and radio at higher and higher volumes.

What will the doctor do?
After determining that ear bone degeneration is the cause of your hearing loss, the doctor may refer you to an ear, nose, and throat specialist (otorhinolaryngologist) to be evaluated for surgical treatment.

If you are a good surgical candidate, the doctor may choose to perform stapedectomy or stapedotomy, both of which are microsurgical procedures done with needle-fine instruments under high-powered magnification. In stapedectomy, the surgeon removes the entire stapes and replaces it with a metal prosthesis about 4.5 millimeters long. One end of the prosthetic stapes is attached to the incus (anvil) and the other is passed through the oval window, the entrance to the inner ear. In stapedotomy, the surgeon makes a hole in the base of the stapes and inserts a small prosthetic device made of wire or Teflon. Either procedure loosens the stapes and permits it to vibrate more freely.

If surgery is not recommended, you should see an audiologist and be fitted with a hearing aid.

The course of ear bone degeneration

Ear bone degeneration usually begins between the ages of 20 and 40 and progresses slowly. In 80 percent of cases, it eventually involves both ears. Surgery to correct hearing loss from ear bone degeneration is usually successful, although a small number of patients suffer auditory nerve damage in the course of the operation and, as a result, have continued hearing impairment that necessitates use of a hearing aid.

Is ear bone degeneration dangerous?
No, but it can lead to almost total hearing loss, which, in turn, impedes social relations and increases the hazards of driving and walking in heavy traffic.

What can I do to avoid ear bone degeneration?

Since this is a genetic condition, there are no known measures to prevent it. If ear bone degeneration runs in your family, be sure to get your hearing checked regularly starting at about age 18.

In otosclerosis, bones of the inner ear become soft and spongy.

In otosclerosis, bones of the inner ear become soft and spongy.
This article was last reviewed November 23, 2005 by Dr. James Krider.
Reproduced in part with permission of Home Health Handbook.
Genetics


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