The Use of Botulinum Toxin Type A in Headache Treatment.

Four percent to 5% of the general population suffers from chronic daily or near daily headache. A majority of them are chronic migraine (transformed migraine), and the rest are chronic tension-type headaches. Prophylactic treatments of migraine and chronic tension-type headache are far from satisfactory because of lack of good efficacy, intolerable side effects, development of tachyphylaxis over long-term use, and drug interactions. Comorbidities and analgesic overuse complicate matters further. There has been an increasing search for more effective treatment for chronic headache, which would result in "modification of the disease." Botulinum toxin type A is an emerging treatment for such patients whose headaches are poorly controlled with currently available prophylactic pharmacotherapy or in patients who do not tolerate them and are unable to continue them. Contraindications to acute migraine therapy such as triptans may also be an indication for alternative treatments like botulinum toxin type A. A number of double blind and open-label trials have been done for migraine and chronic tension-type headache. Although some of the well designed double blind, placebo-controlled, randomized clinical trials are in progress, it has been the clinical experience of many physicians that botulinum toxin type A cuts down the frequency and severity of headaches, improves disability scales, improves quality of life, and reduces the need for acute medications. Repeated use of botulinum toxin type A is needed to sustain long-term improvement, and long-term results indicate lack of tachyphylaxis in the majority of patients. Botulinum toxin type A is well tolerated and totally free of many long-term side effects, which are seen with other prophylactic agents. The clinician may be well advised to consider botulinum toxin type A in the most refractory forms of chronic headaches including chronic migraine and chronic tension-type headache. Appropriate injection techniques, selection of injection sites, and appropriate doses are necessary for success.