Original Article by Jessica Firger. Most of the public knows of Botox as a quick fix for wrinkles, and a mainstay moneymaker in the world of cosmetic treatment. But botulinum toxin (BTX) — a neurotoxic protein produced by the bacterium Clostridium botulinum—has also been used for several decades as an effective therapy for a number of chronic medical problems. In particular, regular injections are often helpful for treating certain central nervous system conditions related to involuntary muscle movement and pain.
The American Academy of Neurology on Monday published new physician guidelines on using BTX for treating stroke, spinal cord or other neurologic injury; cervical dystonia, a disorder of the brain affecting neck muscle control that causes involuntary head tilt or neck movement; blepharospasm, a movement disorder that causes the eyes to close uncontrollably; and chronic and episodic migraine. The drug works by temporarily paralyzing muscles, so in the case of involuntary muscle movement disorders it completely stops contractions. BTX blocks nerve endings from releasing a substance that trigger muscle movement and pain signaling.
The new guidelines were published in Neurology on April 18 and presented at the Academy’s 68th annual meeting. This is the first time the guidelines (last updated in 2008) have included recommendations for migraine patients; Botox for migraines earned approval from the U.S. Food and Drug Administration in 2010.
For some time, using BTX on migraines was primarily viewed as an experimental treatment. However, in recent years, findings from a number of well-designed, placebo-controlled trials on BTX for have shown it to be highly effective tool for migraine management—often more effective than medications and with fewer side effects. In a four-week follow up for one study, patients who received the BTX injections had 15 percent fewer days of headache compared with a placebo.
The new guidelines suggest appropriate uses and doses for the four types of BTX. Most patients aren’t aware that there are several formulations of the injections, and each one works best in different doses and for certain conditions. The four different types of BTX are onabotulinumtoxin A, abobotulinumtoxin A, incobotulinumtoxina, rimabotulinumtoxin B.
Upper limb spasticity, for example, is most effectively treated with three of the drug formulations—abobotulinumtoxin A, incobotulinumtoxin A, and onabotulinumtoxin A. But there is currently not enough evidence to recommend rimabotulinumtoxin B. However, recommendations for all four formulations may change in the future, as more specific clinical trials are conducted that examine the therapeutic benefits of one BTX treatment versus another.
Since the therapeutic effects of BTX last four to six weeks, patient usually need to come back regularly for follow-up treatments—but too much BTX can cause serious side effects and may, in rare circumstances, lead to death. In particular, a systemic infection may result in respiratory failure. In 2009, the FDA issued a black box warning for Botox and other BTX injections after a number of cases occurred where the drug spread far beyond the injection site. These incidences were primarily reported in children with cerebral palsy, who received injections to treat involuntary muscle movement. Regardless, because of the nature of the treatment, physicians should be well-versed in safety of the drug’s use.
An opthamologist developed Botox in the 1970s. He injected it into the extraocular muscles of the eyes to treat strabismus (cross eyes). It worked, and his patients were also delighted to see the injections also provided a new youthfulness by eliminating wrinkles around the eyes.
BTX is used today in a wide variety of specialties beyond neurology and cosmetics. Gastroenterologists sometimes administer the drug to patients in the esophagus to treat a condition that causes throat muscles to spasm. It’s also used by urologists for overactive bladder. But David M. Simpson, a professor of neurology and director of the clinical neurophysiology laboratories at the Icahn School of Medicine at Mount Sinai in New York City and coauthor of the guidelines, says because of the association with cosmetic use, many patients don’t realize that BTX is covered by most insurance plans when a physician deems it necessary for a patient’s treatment and rehabilitation. “This is not a last resort,” says Simpson. “In some situations one might think it should come in very early in the treatment cycle.”