What is botulinum toxin and how does it work?
Botulinum toxin is produced by Clostridium botulinum, a genetically diverse class of anaerobic, spore-forming, gram-positive bacilli. These organisms are ubiquitous in soil and not difficult to isolate. Seven different botulinum toxins have been identified and designated A, B, C, D, E, F, and G. Each of these types is produced by a different strain of the organism. It is not possible to distinguish the type of toxin at clinical presentation. Once absorbed, all types of botulinum toxin are endocytosed by motor neurons. In presynaptic terminals, the toxins enzymatically cleave proteins that are necessary for exocytosis of acetylcholine. The result is a failure of neuromuscular transmission and flaccid paralysis. Because the toxin is not consumed in the reaction, nanogram quantities can induce months of paralysis. How is botulinum toxin used in clinical practice? Formulated as the drug Botox, botulinum toxin type A was approved in 1989 for clinical use in a variety of conditions, includin
