Aug. 4, 2007 Thomas Lynch, age 2, is now able to hear on both sides of his head with a device and surgical procedure pioneered by a surgeon-led team at Loyola University Medical Center.
Born with no ear canal on his left side, Tom had significant hearing impairment and went to Loyola University Medical Center, where Dr. Sam Marzo surgically implanted a bone-anchored cochlear stimulator that delivers sound to the inner ear by bone conduction. Marzo activated Tom’s device at Loyola’s Oakbrook Terrace Medical Center.
“It harnesses the ability of the skull bone to conduct sound vibrations,” said Marzo, associate professor of otolaryngology, Loyola University Chicago Stritch School of Medicine, Maywood, Ill. “It will enable Tom to perceive sounds on both sides of his head, which is critical for his speech development.”
Bone conduction is an alternative way to stimulate the cochlea if the regular sound route—via the ear canal—is interrupted or not available. The cochlea is the snail-shaped part of the inner ear that is responsible for hearing.
The device may be an alternative for people whose deafness cannot be helped by traditional hearing aids or cochlear implants.
The treatment is applicable for single-sided deafness, which affects some 60,000 people each year. The device can be snapped on and off—for showering and sleeping.
“People unable to hear as a result of chronic ear inflammation or drainage can benefit from this new therapy,” said Marzo, who also serves as program director of the Hearing and Balance Center at Loyola’s Oakbrook Terrace Medical Center, One South Summit Ave, Oakbrook Terrace, Ill. “The device will work for people who do not have a functioning ear canal.”
It has successfully treated sudden hearing loss, as well as hearing loss secondary to acoustic neuroma (tumor) and Meniere's disease (excessive fluid in the inner ear.)
Marzo noted that patients must have one working cochlea for the treatment to be effective.
To provide the therapy, a small titanium post is surgically implanted in the skull bone, one-half inch behind the ear. It takes three months for the implant to be integrated into the bone. A 1.5-inch x 1-inch sound processor, which snaps onto the post, transmits sound via bone conduction directly to the cochlea. The result is the sensation of hearing from both ears.
Hearing is an important safety issue, Marzo said. For example, walkers, joggers and bicyclists need to hear oncoming traffic. “Without being able to hear on both sides, it is difficult to perceive direction,” he said.
Marzo has a non-invasive test to determine if the bone-anchored hearing aid will be effective for a patient. To begin, the patient puts on what appears to be a set of headphones. One of the earpieces is placed on the mastoid bone behind the ear. This earpiece is a bone oscillator, the size of a U.S. quarter in radius that will send sound waves to the inner ear via bone conduction. Then, for the test, the patient blocks out any ear canal sound by putting a finger in each ear. The device is turned on. “If they are able to hear at this point, the procedure will work,” said Marzo.
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