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April 2, 2001
Botulinum: Taming the Toxin
By Linda Lowenthal, R.N.

Illustration: Jason Stout

Nancy Boswell*, a gifted 56-year-old floral design artist, has endured three decades of recurrent, debilitating tension headaches. As a teenager, she was involved in a severe head-on auto collision, which doctors believe may have triggered some of her problems. Over the years, she has had two neck surgeries, courses of physical therapy, many sessions of massage therapy, and a variety of medications.

Boswell's responses to these treatments have fluctuated wildly. Many of the drugs she has taken have unpleasant side effects, such as stomach upset or extreme drowsiness. Too often, she has found relief from a headache only after being "knocked out" by strong doses of pain medication -- a familiar situation to those who endure chronic headaches.

Last year, during an unusually severe episode, Boswell's physician injected a tiny amount of a drug called Botox (a commercial preparation of botulinum toxin) into the most painful muscle areas in her head. The next day Boswell awoke free of pain, and she stayed this way for the next five months.

A kinder, friendlier toxin

Historically, the botulinum toxin has been feared as the cause of botulism -- a deadly type of food poisoning -- and as a potential biological weapon. In recent years, however, the toxin has developed a new image, that of a kinder and friendlier potion that can help people manage some unpleasant medical conditions and even cosmetically enhance their appearance.

Botulinum toxin is made from a bacterium called Clostridium botulinum. When brought into contact with the nerves leading to muscles, the toxin blocks the transmission of signals from nerves that cause the adjacent muscles to contract. When that happens, the muscles become completely flaccid and relaxed, or paralyzed. This type of paralysis is temporary; over the ensuing weeks or months, the nerve gradually sprouts new pathways that reconnect to the muscle and previous functioning resumes. For those who are concerned about poisoning from botulinum toxin, known as botulism, take note: Botulism is most often associated with the consumption of improperly canned foods. The progressive total paralysis and respiratory failure that can result from ingesting tainted foods is caused by a huge overdose of botulinum toxin -- more than 30 times the amount contained in a typical injection of Botox.

About 25 years ago, medical researchers hypothesized that tiny, carefully calibrated doses of the botulinum toxin, when injected locally into specific muscles, could temporarily eliminate overactive and unwanted muscle contractions. The first applications to humans involved the treatment of eye-muscle contraction disorders, including eyelid spasms and gaze-alignment problems. The results were promising, and physicians began to consider using the toxin to treat other disorders involving abnormal muscle activity. In recent years, physicians have used Botox to alleviate muscle tension that is characteristic of certain types of neck, shoulder, and head pain.

"The medications that we traditionally used for certain chronic neck problems and protracted headaches at the base of the head were not nearly effective enough for some patients," says Craig R. DuBois, M.D., medical director of the Pain Evaluation Treatment Center and Seton Northwest Hospital Pain Center, in Austin, Texas. A board-certified neurologist, Dr. DuBois is also Boswell's doctor. "When we began using Botox for some of these disorders," he says, "we saw considerable pain relief along with the muscle relaxation."

Thanks to the relief provided by Botox injections, Dr. DuBois's patients have been able to cut back dramatically on their use of other pain medications, systemic drugs that can have adverse side effects, such as sedation and damage to the gastrointestinal tract, liver, or kidneys. Botox exhibits none of these side effects, primarily because it affects only the muscle into which it is injected. The most common side effect is a temporary weakening of the muscles in the area of injection. "Botox has the advantage of not causing any nerve destruction or sensory loss; it does not have widespread or lasting systemic effects -- its specificity to a muscle is probably its greatest calling card," Dr. DuBois says.

Other uses of Botox

Researchers and physicians have explored new uses for Botox, in large part because of the drug's positive safety and side effect profile (which has been compiled over more than two decades). The major drawbacks are the necessity of repeat injections, as the benefits wear off, and the cost; Botox is relatively expensive. Future research will focus on the development of agents that act similarly to Botox in terms of muscle relaxation, safety, and side effects, but that have a longer period of effectiveness. So far, Botox is being used to treat conditions such as the following:

  • Focal dystonias. These are involuntary, repetitive muscle spasms that affect a particular part of the body and cause distorted movements or postures. Examples include torticollis (wryneck), writer's cramp, and disorders of the vocal apparatus in the throat. Botox relaxes the affected muscles.
  • Spasticity. Botox is used to help prevent leg muscle contractures in children with cerebral palsy and to treat spasticity associated with multiple sclerosis or spinal cord injuries.
  • Gastrointestinal disorders. Sphincters (rings of muscle tissue) located along the digestive tract may remain closed, preventing the normal digestion of food. Botox relaxes the sphincters, enabling them to function properly.
  • Cosmetic. Botox can significantly reduce the prominence of frown lines and crow's feet.
  • Excessive sweating. Botox can block the signals from nerves that trigger hyperactive sweat glands in the armpits and palms.
  • Tension headaches. Early studies have shown that Botox may benefit certain individuals who are not helped by standard medications or therapies.

Not a miracle cure

Although Botox is a promising treatment for certain cases of tension headaches, DuBois has some cautions. "The only problems I've noted with Botox have been associated with the necessity of finding just the right dosage for each individual patient, in order to accomplish the desired effect without inducing excessive weakness," he explains. "And now that Botox is being used in so many specialties, I have concerns that it may be overused."

Unfortunately, Boswell's headaches did return, but a second series of Botox injections has brought gradual improvement and has helped to render her situation livable. According to Boswell, Botox may prove to be a useful part of a program to manage her symptoms. Although she still must take other medications, she takes lower doses, avoiding many of the side effects. In regard to Botox being a "miracle cure," though, Boswell seems to balance hope and realism. "I know I'll continue to have some bad days," she says, "but there will also be the good ones."

*Not the patient's real name

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