Emerging therapeutic applications of botulinum toxin.

Botulinum toxin, the most potent known biological neurotoxin, holds great promise in the therapy of many diseases. It has been used effectively to treat strabismus, dystonias and other movement disorders, and spasticity. However, a number of potential new therapeutic indications have emerged and attracted a considerable amount of interest from the scientific community. These emerging indications included treatment for conditions associated with pain (e.g. headaches, myofascial pain, chronic low back pain), hypersecretion of glands (e.g. hyperhidrosis, sialorrhea, intrinsic rhinitis), and excessive or dyssynergic muscle contraction, and for cosmesis (e.g. myokymia, bruxism, anal fissure). There is a need for more controlled clinical trials, dose-ranging studies to determine optimal treatment, validated clinical scales and studies developed to assess the value of electromyographic guidance and skill of investigators on the outcome of treatment for some of these diseases. The long-term cost effectiveness of treatment and immunoresistance from repeated injections are also important clinical issues to address.