Rationale for Treatment with Botulinum Neurotoxin

Botulinum toxin induces weakness of striated muscles by inhibiting transmission of motor neurons at the neuromuscular junction. This has led to its use in conditions with muscular overactivity, such as dystonia. Transmission is also inhibited at y neurons in muscle spindles, which may alter reflex overactivity. 

The toxin also inhibits release of Ach in all parasympathetic and cholinergic postganglionic sympathetic neurons. This has fueled interest in its use as a treatment for overactive smooth muscles (for example, in achalasia) or abnormal activity of glands (for example, hyperhidrosis). Over the past 15 years, botulinum toxin has been shown to be useful in many conditions, especially strabismus and various movement disorders (Table 16.1). 

Encouraging clinical reports have generated an abundance of ideas for other uses. Following are examples of overactive muscle conditions and other disorders for which treatment with botulinum toxin A has been tried (Munchau and Bhatia, 2000). 

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