Treatment with botulinum toxin: An update

Botulinum neurotoxin(Bo NT) is a potent toxin produced by the anaerobic bacterium clostridium botulinum. It causes flaccid, long-lasting, local and reversible paralysis. In addition, Bo NT inhibits the secretion of the exocrine glands and could have properties in the control of pain. Thus, Bo NT is useful in the treatment of many neuromuscular conditions where an increase of muscle tone is associated with the pathogenic mechanism. Furthermore, Bo NT is recommended in the treatment of some hypersecretion disorders of the exocrine gland and could play a role in the treatment of migraine and other chronic pain conditions. In the Bo NT therapy adverse effects are usually mild and reversible. However, repeated injections of Bo NT can lead to the development of neutralizing antibodies that can subsequently inhibit the biological activity of the toxin. In this sense, many factors can influence the immunogenicity of the Bo NT, such as product-related factors, the dose of Bo NT used, the frequency of injection and the previous exposure to the toxin. In this review, we are going to discuss the current clinical applications of Bo NT with a special focus on evidence, doses, injection technique and adverse effects for those applications more frequently used in neurology, namely spasticity, blepharospasm, hemifacial spasm, cervical dystonia and other focal dystonias, as well as chronic migraine, tremor, sialorrhea, facial palsy, neurogenic bladder and many other neurological condition.