STORY BYDr. 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.
UPDATED: 2-07-2006
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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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Food Irradiation
and Safety
On August 22, 2008, the Food and Drug Administration (FDA) published a final rule that allows the use of irradiation to make fresh iceberg lettuce and fresh spinach safer and last longer without spoiling.
Irradiating fresh iceberg lettuce and spinach will help protect consumers from disease-causing bacteria such as Salmonella and Escherichia coli O157:H7 (E. coli). Illnesses from these bacteria range from uncomfortable symptoms to life-threatening health problems.
The foods affected by the final rule are
Irradiation (also sometimes termed "ionizing radiation") is a process of treating products with a measured dose of radiation. Food irradiation is not new. FDA has conducted irradiation safety evaluations for more than 40 years and has determined the process to be safe for use on a variety of foods.
After studying the safety of irradiating fresh iceberg lettuce and fresh spinach, FDA has determined that these greens, when irradiated under the conditions specified in the final rule, retain their nutrient value and are safe to eat.
FDA considers irradiation a complement to, not a replacement for, proper food-handling by producers, processors, and consumers. Irradiation is just another tool to reduce the levels of disease-causing microorganisms on fresh iceberg lettuce and fresh pinach.
Irradiation does not take the place of washing. FDA continues to recommend that consumers wash fresh and bagged produce before eating unless the packaging specifically states that the product has been pre-washed.
For more information, go to: http://www.fda.gov)
