Voice tremor responds to injections of Botox into the vocal cords, researchers have shown.

Voice tremor can be part of a common movement disorder called essential tremor, or it can exist by itself. The condition is often “very embarrassing and disabling,” Dr. Charles H. Adler, at the Mayo Clinic Scottsdale, Arizona, and colleagues note in the medical journal Archives of Neurology.

Oral medications don’t help much, but small studies have shown that the disorder may respond to Botox injections. The prompted the researchers to conduct a study with 13 patients, ages 54 to 81 years, with voice tremor but without tremor in the head, mouth, jaw or face, or any signs of Parkinson’s disease.

On scales of 0 to 4, the average severity of voice tremor was rated 3.00, and functional disability averaged 2.31.

The participants were randomly assigned to get various doses of Botox injected into each vocal cord and were followed for 6 weeks.

All the subjects perceived some effect from the treatment, beginning 1 to 7 days after the injections. By 6 weeks, average severity score was reduced to 1.31, while functional disability score declined to an average of 0.85.

“Independent ratings of videotaped speech, and acoustic measures of tremor also showed improvement,” Adler’s team notes. The number of patients was too small to tell if larger doses produced a greater response, the investigators add.

Adverse effects were mainly breathiness and difficulty swallowing, rated mild to severe, which improved in all patients but one after 6 weeks.

“The results of our study show that (Botox) is a promising treatment for voice tremor, and further controlled studies should be pursued,” the researchers conclude.

SOURCE: Archives of Neurology, September 2004.