WASHINGTON -- A federal advisory panel recommended yesterday the expanded use of botulinum toxin for certain muscle spasm disorders, saying that injections of minute amounts of the lethal substance can be a safe and effective therapy for hundreds of thousands of Americans.
"We've seen . . . impressive evidence that this is the first choice of treatment for several disabling disorders," said the panel's chairman, Dr. Roger Duvoisin, chief of the department of neurology at the Robert Wood Johnson Medical School in New Brunswick, N.J. "Because of the high success rates of the toxin treatment, thousands more patients have the potential to lead improved lives."
Botulinum toxin, a complex protein produced by bacteria that can cause often-fatal food poisoning, has been studied for nearly a decade as a treatment for temporarily relieving isolated muscle spasm disorders. These include involuntary contractions of the eyelids, misalignment of the eyes and facial spasms. "It has given relief where little was available before," Dr. Duvoisin said.
Earlier this year, the Food and Drug Administration approved the use of the toxin for the treatment of these afflictions.
But the panel, convened by the National Institutes of Health in Bethesda, recommended that the toxin also be used for treating vocal cord spasms and neck spasms. They also called the substance a promising therapy for stuttering and numerous other spasms, including those of the mouth, jaw and limbs.
The toxin works on muscles by chemically blocking the connection between the nerve and the target muscle, essentially weakening the muscle. Small amounts used in therapy relax the muscle, thus reducing the spasm and allowing the patient to move more freely. Larger amounts -- as in botulism poisoning -- can cause paralysis and death.
The panel said that the toxin could be administered "to musicians, typists and others whose careers may be jeopardized by musician's cramp or writer's cramp."
The effect of the botulinum toxin is temporary and usually lasts several months, meaning that repeated injections are required to sustain the benefits over a long period of time.
For that reason and others, the panel said that botulinum toxin therapy is not a cure for chronic neurological disorders, such as Parkinson's disease. But it called for further research to determine its value in that area, as well as in treating cerebral palsy and spasticity in multiple sclerosis, and urinary and anal sphincter dysfunction.