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

Posted: December 7, 2010

NOTE: Only on SkinInc.com: Exclusive spa-focused commentary by Skin Inc. magazine advisory board member Steven Dayan, MD, follows this news item explaining why or why not this news should be concerning to your clients.

A new study by researchers at the Faculty of Kinesiology, University of Calgary, is raising questions about the therapeutic use of botulinum toxin A.

The study found that animals injected with clostridium botulinum type A neurotoxin complex experienced muscle weakness in muscles throughout the body, even though they were far removed from the injection site. The study also found that repeated injection induced muscle atrophy and loss of contractile tissue in the limb that was not injected with the toxin.

"We were surprised by the degree of muscle loss and atrophy in the limb that was not injected with the Botulinum toxin," says Rafael Fortuna, the lead author of the paper that will soon be published in the Journal of Biomechanics. "I think it's fair to say that the paper raises some important questions about the long-term therapeutic use of Botox, especially with children and adolescents."

The study used dosages that approximated therapeutic doses used to treat conditions like cerebral palsy where muscle contraction can't be controlled, resulting in muscle dystonia and spasticity. The study follows previous lab research from Walter Herzog, PhD, which found that botulinum toxin A, easily crosses the muscle membrane barrier, resulting in weakness in the surrounding (noninjected) muscles.