Therapeutic Application of Botulinum Toxin in Clinical Practice

Abstract

Botulinum toxin, one of the most potent toxins known, is produced by Clostridium botulinum. It causes a tem- porary paralysis of muscles by inhibiting vesicular release of acetylcholine in neuromuscular junction and synaptic trans- mission at cholinergic nerve terminals and causes a temporary paralysis of muscles. Since the approval of botulinum toxin A by FDA for strabismus and blepharospasm in 1989 and botulinum toxin B for cervical dystonia in 2000, its therapeutic uses are expanding. To date, both the serotypes A and B have been used therapeutically. These include various dystonic movement disorders, lacrimal hypersecretion, hyperhydrosis, overactive bladder syndromes both neurogenic and idio- pathic, prostatic hyperplasia, various gastrointestinal disorders, headache syndromes like migraine and various spastic disorders. Botulinum toxin does not correct the underlying pathology but only produces clinically symptomatic improve- ment. The duration of improvement and the percentage of improvement vary between different studies due to differences in doses used; different techniques used for injections and also the dilutions. Still more trials are required to explore newer indications of its use, to find out the exact effective doses, dilutions and techniques, so as to have a prolonged clinical im- provement. Though it has a good safety profile, complications are related to chemodenervation of adjacent muscles and injection techniques. This article provides an update on different uses of botulinum toxin in medicine.