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Medicine | IN THE LAB

For damaged vocal cords, surgery may not be only option

August 23, 2004|Shari Roan | Times Staff Writer

The ability to be heard across a room is something most people take for granted. But for Americans with vocal cord disorders, the simple act of speaking is difficult, uncomfortable and, ultimately, discouraging.

The best treatment so far has been surgery. Now doctors have begun studying whether a simple injection of a bone-like substance can correct the raspy, weak and breathy voices of people who have paralyzed, partially paralyzed or weakened vocal cords.

"There are a lot of patients right now, especially elderly patients, who are troubled by their voice, but they are not interested in having surgery," says Dr. Clark Rosen, an otolaryngologist and director of the University of Pittsburgh Voice Center. "When I tell them 'I think we can improve your voice by having an injection right here in the office,' they become very interested."

Vocal cord problems can be caused by injuries, stroke, lung or thyroid cancer or infections. In most cases, one of the two vocal cords doesn't move or is partially paralyzed or weakened.

For more than a decade, an operation called laryngoplasty has been used to treat the condition. The surgery involves adding bulk to the paralyzed cord -- usually in the form of a plastic implant -- and changing its position to reduce the space between the cords.

"That works quite well," says Rosen, who is testing the bone-like substance. "But you are making a scar in the neck and dissecting through the tissue of the neck and putting a foreign object in. It's a lot of work."

Doctors have long experimented with other solutions, usually by injecting some type of substance into the vocal cord. They've tried Teflon, collagen, silicone and a patient's own fat. But most of the substances break down or are rejected by the body, Rosen says.

"The ideal injection material would be well-tolerated," he says. "It would be stable. When you put it in on Day 1, it would stay the same three, four, five years down the road. And we would be able to do it through a small needle so that you can do this injection in the office."

A study underway will attempt to show whether calcium hydroxylapatite may be that long-sought substance. The material is a form of calcium phosphate that is present in bones and teeth. It is already used in bone implants and to fill cranial or facial defects. The material is approved by the Food and Drug Administration for these and similar uses.

The injection consists of tiny spheres of calcium hydroxylapatite suspended in a gel. When injected into vocal cords, the gel eventually dissipates and tissue forms around the spheres to augment the vocal cord.

A previous study to be published next month in the Journal of Voice showed the substance was safe and improved voice quality in six patients followed for six months. The new study will be a much larger, more rigorous test. Researchers from 15 study sites will test the injections in 150 patients.

Many doctors who treat voice disorders will have to be convinced that calcium hydroxylapatite is a satisfactory injection material and is a better option than surgery, says Dr. Jamie Koufman, a voice rehabilitation surgeon at the Center for Voice Disorders at Wake Forest University.

In an e-mail interview, Koufman says she suspects that, like other substances, the calcium hydroxylapatite will eventually be reabsorbed by the body.

"Laryngoplasty is still by far the best procedure, in my opinion," she says. "I can get a normal voice most of the time with laryngoplasty."

In the future, techniques to improve voice quality may be achieved through implants that can be placed in the cord with an endoscope -- a thin tube with an optical system -- or with bioengineered tissue added to the cords, Koufman says.

The study, however, should follow patients long enough to provide some idea of the permanence of the injections, Rosen said. The study will be completed in about two years.



How the vocal cords work

The vocal cords are two stretchy bands of tissue in the larynx (the voice box) directly above the trachea (the windpipe). Sounds are made when air in the lungs is released, passing through the closed vocal cords and causing them to vibrate.

When a person isn't speaking, the cords are open to allow the person to breathe. Paralyzed or weakened cords, however, remain open, leaving the lungs unprotected.

In addition to suffering from voice problems, people with vocal cord paralysis can have trouble swallowing and coughing.

Source: National Institute on Deafness and Other Communication Disorders

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