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Does Botox Cause Muscle Weakness over Time? With Exclusive Commentary From Steven Dayan, MD

Posted: December 7, 2010

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This study shows, for the first time, that in time Botulinum toxin A use also results in muscle weakness, atrophy and loss of contractile tissue in non-injected muscles far removed from the injection site."It may be that the benefits of using Botox for these kinds of therapeutic, medical uses, outweighs these potential long-term consequences," says Herzog, "however, I think this study raises some important issues that need to be followed to ensure the best possible outcomes for patients, in the long term."

Botulinum Toxin A is also used as a cosmetic treatment, where the drug paralyzes small muscles in the face to reduce the appearance of wrinkles. Herzog notes that while this study was looking at larger doses, the results should be valid for any application of the drug.

From www.sciencedaily.com, Dec 2, 2010

Exclusive Commentary from Skin Inc. magazine Advisory Board Member Steven Dayan, MD, Explaining Whether There is Cause for Concern

“The recent article published in the Journal of Biomechanics evaluates the effects of high doses of Botox on the muscles being treated and the surrounding muscles in New Zealand rabbits. The authors conclude that Botox can lead to muscle wasting, fatty infiltration into the muscles and long-distance weakness of other untreated muscles that may result in cumulative defects to the distant muscle groups. This study, although being debated by the media, has little to no significance to the cosmetic clinical treatment that is used today. First of all, they gave the Botox to rabbits. Rabbits are very different than humans. Secondly, they gave very high doses of Botox and gave it monthly for six months. This would be the equivalent of giving 240 units of Botox to someone every month for six months! That is very unrealistic. The normal dose of Botox given cosmetically is around 30 units. The 240 units used in the study are seven times the normal cosmetic dose.

"Their conclusion that surrounding muscles were effected with long-term weakness is also a poorly supported statement. They tested nearby muscle groups. When giving high doses of Botox, who is to say that some of the Botox didn’t diffuse over to the nearby muscles by overwhelming natural transport mechanisms? Why didn’t they look at muscle groups in the forelimbs or shoulders if they wanted to test distal spread? Perhaps the opposite hind limb in rabbits is naturally underutilized when one hind limb is effected? They didn’t do biochemistry studies to confirm if Botox was taken up in those nearby muscle groups. Additionally, if Botox long-term leads to muscle atrophy and fatty infiltration, that would be welcomed by many of my patients, because that could mean that Botox may have long-lasting effects. But in all likelihood, the muscle activity would return once the Botox was stopped. The authors didn’t test this though. Botox has been used clinically for 25 years in both high and low doses with an unparalleled safety record and, when used as indicated for cosmetic use, the safety record is outstanding. Bottom line: Botox is still one of the safest and most reliable cosmetic treatments available.”