Dr. Shaw said that in his experience, human collagen, like the CaHA gel, can last even longer and may even offer a permanent fix. It’s a little difficult to work with because it is so viscous, but definitely it is a step up in that there is not nearly as much resorption as with fat or bovine collagen, he said.
Explore This IssueOctober 2009
Another disadvantage, Dr. Garrett said, is that human collagen requires extra time for reconstituting and preparation-you have to mix it with lidocaine in the clinic setting or saline in the operating room. There is a definite learning curve.
Cross-linked bovine collagen (Zyplast/Zyderm) is another effective material that comes ready to inject, Dr. Garrett said. The big drawback is the need for allergy skin testing [about two weeks before] injection to ensure there will not be any hypersensitivity reaction.
Dr. Shaw added that up to 70% of the material is resorbed so you really need to reinject about six months to two years later.
Hyaluronic Acid, Bovine Gelatin, Teflon
Yet another filler introduced since 1980 is hyaluronic acid, a crosslinked nonimmunogenic polysaccharide, said Dr. DeVore. Widely used as a filler in facial plastic surgery, hyaluronic acid can also be used as a temporary injection material to medialize the paralyzed vocal fold, he said.
Dr. Garrett said she doesn’t know of anyone who still uses it, mainly due to an unpredictable duration of effect. One potential advantage, however, is that it is technically easier to inject, she said.
Introduced in 1978, bovine gelatin (Gelfoam) is still available as a temporary injectable. But most otolaryngologists have switched to newer materials due to the need to use a large, 18 gauge needle and a short duration of effect-about four to six weeks.
First introduced in the 1960s, Teflon is also rarely used anymore, in this case because of a high risk of side effects, chiefly foreign body reaction or vocal fold granuloma formation in more than 50% of patients, Dr. Garrett said.
It is probably the only one of the injectable that has shown permanent results, but the complication rate keeps most people from using it, she said.
Botulinum toxin type A, the muscle weakening agent better known as Botox, has been used off-label for years to help people with spasmodic dysphonia, a neurological disorder in which the laryngeal muscles are hyperactive on certain sounds, making the voice sound strained, broken, or breathy. The shots relax the muscles in the vocal cords, improving voice.