[High doses of botulinum toxin, from efficacy to safety: experimental data]

Experimental studies in the animal have not been designed to specifically address the use of high doses of botulinum toxinum. However, it allows us to draw some very interesting findings. First, it has been showed that efficacy correlates to the dose, albeit up to a point beyond higher doses do not induce a greater benefit. Over this "ceiling" dose, the risk of migration outside the targeted muscle increases. The systemic risk is superior to the local risk. The efficacy could differ according to the number of injected muscles, and according to the type of toxin. What has been observed in the animals tend to be confirmed in human, despite precise studies are still lacking. Thus, experimental data support our daily clinical experience and provide us some very useful informations when high doses are injected. They especially help us to keep in mind the systemic risk which is, most of the time, unclear in our daily practice.