September 16, 2011
By Harvey B. Simon, M.D.
Harvard Medical School
Botulinum toxin (Botox) causes a deadly type of food poisoning. It's also considered a potential weapon of bioterrorists. But in recent years, Botox has earned a highly favorable reputation as a medication.
First came its well-known role as a cosmetic treatment for wrinkles. More recently, it has been used to treat several problems ranging from migraine headaches and excessive perspiration to muscle spasms and tennis elbow.
Urologists have been testing Botox for a variety of urinary tract problems. Just last month, the U. S. Food and Drug Administration (FDA) approved Botox to treat patients who lose bladder control because of nervous system diseases.
Men of a certain age may be glad to learn that benign prostatic hyperplasia (BPH) or enlarged prostate may someday join the list of conditions that can benefit from Botox.
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What is Botox?
Botox is a protein made by a bacterium called Clostridium botulinum. It makes botulinum toxin, which binds to nerve fibers. This prevents them from releasing acetylcholine, a chemical that allows nerves to communicate with muscles and other nerves. Without this chemical messenger, muscles can't contract properly. This muscular paralysis results in the disease called botulism.
Clostridium botulinum lives in soil and in the intestinal tracts of humans and animals, where it is harmless. But it forms spores that can contaminate food. Normally the spores are inert; pressure-cooking or heating food can destroy them. But if contaminated food is eaten or not handled properly, the spores come to life and make the hazardous toxin.
In mild cases, symptoms include dry mouth, blurred vision, decreased sweating, constipation and urinary retention. If enough toxin is swallowed, however, the patient becomes weak, then paralyzed. Even with the best modern treatment, 25% of victims die from respiratory paralysis. To prevent botulism, cook your food thoroughly, refrigerate leftovers promptly and reheat them before eating.
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Cosmetic and Medical Uses
Botox is most often used to reduce facial wrinkles. This cosmetic use of Botox is safe and effective, but it has raised some eyebrows.
Botox paralyzes the facial muscles so that the skin looks smooth. (The trick is to purify the toxin and inject minuscule amounts directly into the target tissues.) It wears off in a few months, and the wrinkles return. New injections restore the Botox look and earn hundreds of millions of dollars for drug makers and dermatologists each year.
Using Botox injections to treat medical conditions is less controversial. Some of the conditions include:
- Strabismus (crossed eyes)
- Blepharospasm (twitching eyelids)
- Dystonia (sustained muscle spasms of the neck or other areas)
- Hemifacial spasm (grimacing and twitching of one side of the face)
- Achalasia (spasm of the lower esophagus that impedes swallowing)
- Rectal fissures
- Hand tremors
- Excessive sweating
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Botox and the Bladder
Doctors began using Botox injections for certain bladder problems more than 20 years ago. Many clinical trials have reported that Botox injections can help improve urinary control in patients with neurologic disorders, such as spinal cord injuries and multiple sclerosis. These favorable results led the FDA to approve Botox for these patients in 2011.
The major clinical studies of Botox are in patients with a condition called detrusor hyperactivity, better known as overactive bladder. It's caused by sudden contractions of the bladder wall (detrusor) muscle before the bladder is full. This leads to an uncontrollable urge to void. People with overactive bladder often leak urine before they can get to a bathroom.
Botox injections have also been used to treat another bladder disorder called urge incontinence. This condition affects men and women. Some patients don't respond to oral medications that relax the bladder muscle. Or they have troubling side effects from the medication, such as dry mouth and constipation.
Botox is injected directly into the bladder's detrusor muscle. It's hoped that the FDA may soon approve Botox for people whose urge incontinence is not related to nervous system disease. The benefit lasts for many weeks and most patients tolerate the injections well, but some develop bleeding or urinary retention that may require a catheter to empty the bladder.
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Botox and BPH
Young men may be proud of big biceps, but older men do not welcome big prostates. Surprisingly, perhaps, the prostate has muscles. BPH is caused by the enlargement of the glandular tissue, not the muscle fibers. Still, many of the most effective medications for BPH act by relaxing the muscles in the prostate and bladder neck to ease the flow of urine. But they can have side effects and they require taking a pill every day.
Most studies of Botox in men with enlarged prostates, slow urine flow rates and moderate to severe voiding symptoms have had favorable results. Most volunteers have been over age 50. In a typical study half the men are randomly assigned to get Botox while the others receive placebo injections. Transrectal ultrasounds are used to guide the injections, which do not require anesthesia and have been well tolerated.
Some trials also report that Botox helped shrink the prostate and lowered blood levels of prostate specific antigen (PSA). And in many cases, the apparent benefits of a Botox treatment lasted for 12 months or even longer. Few urinary side effects have been reported and Botox does not seem to cause sexual problems.
The decreases in prostate size and PSA levels result from a newly-recognized effect of Botox: It appears to actually slow the growth of prostate cells.
Despite the promising results of early studies, Botox has not been approved for BPH. Much more research will be needed before that can happen. Still, there is reason to hope that this old toxic foe may one day be a friend to men with BPH. That new wrinkle would certainly turn some frowns into smiles.
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Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.