Botulinum toxin, long an outcast in culinary circles, is one of the most potent positons known. But it is currently finding gainful employment in the medical world.
In food-borne botulism, the toxin is absorbed into the body after food contaminated with Clostribudium botulinum is eaten. The poison then paralyzes muscles by preventing nerve endings from releasing the chemical signal for muscle-cell contraction. The paralysis is progressive, usually beginning with muscles responsible for eye movements, swallowing, and speech and continuing with those controlling the trunk and extremities. When the muscles involved in breathing become affected, death can occur.
For many years researchers have been studying ways to make a virtue of these vices. Now the U.S. Food and Drug Administration has approved us of the toxin to treat two muscle disorders affecting the eyes, blepharospasm and strabismus.
Blepharospasm (uncontrollable winking caused by muscle contractions in the eyelids) can usually be relieved by injecting small doses of botulinum toxin directly into the muscles involved. In 90% of patients the spasms will then abate for two to four months. When symptoms recur, additioanl injections will be just as effective as the first ones.
People with strabismus ("crossed" eyes) can also benefit from the home canners' nemesis. In a recent study of 356 children, the eyes were satisfactorily aligned in 133, or 37%, after a signle injection, an in 90 of 144 (63%) who went on to receive one or more additional injections. Among a subset of children who achieved satisfactory alignment, 85% retained it two years later. The toxin has also been successfully used to treat children whose eyes have been overcorrected by surgery for strabismus. Adults, too, can benefit, although perhaps not quite so dramatically.
Research on certain other disorders of muscle control indicates that they may also be helped by treatment with botulinum toxin. These include severe, prolonged face and neck spasms, as well as voice disorders due to unusual spasm of muscles controlling movements of the larynx. There is even preliminary evidence that the toxin, when injected into the small laryngeal muscles, can improve stuttering. (Medical Letter, November 2, 1990, pp. 100-102; JAMA, November 28, 1990, pp. 2671-2675.)
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