I think you may have heard about an article that has been reported in different internet venues and was the one in the Journal of Biomechanics that appeared last year. In this animal study, they examined the effects of Botox on not only the muscles that were injected but on the surrounding muscles as well. They found that Botox did lead to local muscle wasting as well as weakness of other untreated muscles in the region.
This study has caused a little bit of hullaboo about Botox but, in our opinion, it has no relevance to the cosmetic use of Botox. Beyond the fact that this was done in animals (rabbits), the doses were very high compared to what we use in humans. By our calculation, they were giving the equivalent of 200 to 300 units of Botox every six months. Given that the normal cosmetic dose of Botox is around 24 to 36 units, their dosing was nearly 10X that of a cosmetic facial treatment. The muscles that they injecting were voluntary motor muscles as opposed to involuntary muscles of facial expression. These are quite different types of muscles. Motor muscle are well known to atrophy from simple disuse, muscles of facial expression do not display this atrophy phenomenon. Most of our cosmetic patients would welcome that if it happened but there has been no evidence that it occurs.
This article is an interesting piece of science but its findings do not hold a candle to the 25 years of human Botox use in which this permanent muscle weakening effect has never been seen in a low-dose cosmetic application. And yes, as the Botox gradually wears off the wrinkles gradually come back.
Pam Greenspring R.
Feb 2, 2013