Health Leader, Good Vibrations

STORY BY

Meredith Raine

Dr. C. Y. Joseph Chang pulls a ring box out of a filing cabinet and proposes an option that will allow some of his patients to regain hearing.

Inside the box is the external piece of a bone-anchored hearing aid. It looks more like the shift key on a computer keyboard than a piece of jewelry, but it is indeed a treasure to some patients who cannot wear conventional hearing aids.

The bone-anchored hearing aid is a surgically implantable system that works through direct bone conduction, meaning it allows sounds to be conducted through the bone rather than via the middle ear.

This type of hearing aid is designed primarily for patients with congenital ear malformations, chronic ear infections or single-sided deafness.

“The bone-anchored hearing aid is a very good option for some patients with severe conductive and mixed hearing impairments,” says Chang, professor and chairman of the Department of Otolaryngology— Head and Neck Surgery at The University of Texas Medical School at Houston. “If you are born without an ear canal, you can’t hear much at all, but the inner ear is usually intact. Also, patients with chronic ear infections can’t put a traditional hearing aid in their ear. This system allows us to work around that.”

The bone-anchored hearing aid consists of a titanium implant, an external abutment and a sound processor. It works by enhancing natural bone transmission as a pathway for sound to travel to the inner ear, bypassing the external auditory canal and middle ear. During a short surgical procedure, Chang removes a small amount of soft tissue from behind the ear and implants the 3-4 millimeter titanium post in the skull.

After about three months, when the area around the post has healed, Chang hooks the external piece onto the post. The sound processor—which can be worn throughout the day, except when showering or swimming—transmits sound vibrations through the external abutment to the titanium implant. The vibrating implant sets up vibrations within the skull and inner ear that finally stimulate the nerve fibers of the inner ear. This allows patients to hear.

Chang says this technology has been widely used in Europe since the late 1970s. Only recently have U.S. patients benefited from bone-anchored hearing aids. This upgrade of traditional bone conduction devices has eliminated the need for bulky headbands and eyeglasses that were used in the past to keep the bone conductor in place.

Bone-anchored hearing aids are primarily implanted in adults, but children as young as age 6 also are candidates.

Most recently, the bone-anchored hearing aid has been approved for patients who are completely deaf in one ear.

“The bone-anchored hearing aid will stimulate the other ear,” Chang says. “This allows patients to hear without turning their heads. This is remarkable for patients who have only been able to hear out of one ear.”

The system does have a few drawbacks, Chang says. “There is a tiny piece of metal protruding from the scalp skin that requires local care so it doesn’t become infected.” Overall, Chang says, the bone-anchored hearing aid is one more tool physicians can use to help patients hear.

Last Updated: 2-07-2006

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About Dr. Chang

Dr. Joseph Chang is professor and chairman of the Department of Otolaryngology—Head and Neck Surgery at the UT Medical School.

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Health Tip:

Packing Bag Lunches Safely

If you pack lunches for your child to take to school, be careful that you do not accidentally expose them to foodborne illness.

Bagged lunches, especially those containing perishable foods, need to be packed and handled properly in order to keep the food safe. In general, perishable foods should not be left at room temperature for more than two hours. If left out too long, the temperature of the food can enter the danger zone where bacteria grow most rapidly, which is between 40 and 140 degrees Fahrenheit.

Below are some tips to help families pack bagged lunches safely:

Pack foods that are nonperishable and won't require refrigeration.
If you do pack perishable foods such as luncheon meats or prepackaged cheese and crackers, include a frozen gel pack or a frozen juice carton with the food in an insulated lunch bag or box.
Pack only the amount of perishable food that your child can eat at lunch.
Preparing lunches the night before and storing them in the refrigerator until you pack your child's lunchbox in the morning can help keep food cold longer the next day.
Don't reuse packaging materials such as paper or plastic bags, aluminum foil, etc. as they can contaminate other foods and cause foodborne illness. Have your child discard all used food packaging and paper bags after lunch.

Before eating lunch or snacks at school, make sure your child washes his or her hands with soap and warm water for at least 20 seconds. If your child's school does not have a handwashing program in place, encourage them to adopt a such a program, as handwashing is one of the best ways kids and parents can protect health and stop the spread of germs.