Botulinum toxin in migraine prophylaxis

Migraine is a chronic headache disorder manifesting in attacks lasting 4-72 hours. Characteristics of headache are unilateral location, pulsating quality, moderate or severe intensity, aggravation by routine physical activity, and association with nausea, photophobia and phonophobia. The migraine aura is a complex of neurological symptoms, which occurs just before or at the onset of migraine headache. Botulinum toxin A represents a completely new option for patients with chronic pain conditions. Numerous retrospective open-label chart reviews and 4 double-blind, placebo-controlled studies have demonstrated that botulinum toxin type A is significantly effective in migraine prophylaxis and reduces the frequency, severity, and disability associated with migraine headaches. Studies have generally reported a good and consistent efficacy. The differential therapeutic use of botulinum toxin appears to be worth attempting in migraine patients with the following characteristic features: (1) Muscular stress as migraine trigger, e. g., in craniocervical dystonia, pericranial painful muscular trigger points or tender points, oromandibular dysfunction, (2) concurrent chronic tension-type headache with the aggravating factors of muscular stress or oromandibular dysfunction, (3) chronic migraine with frequent migraine attacks on more than 15 days per month for longer than 3 months and if other therapeutic options have been either ineffective or have not been tolerated. The use of the agent does not cause CNS side effects. Migraine patients in particular, often suffer greatly, as a result of the adverse effects of the drugs used, from fatigue, dizziness, reduced concentration, loss of appetite, weight gain, hair loss and changes in libido. These side effects are not known in association with botulinum toxin A. To date, neither organic damage nor allergic complications have been reported. Thus, both the tolerability and the safety of this therapeutic measure are high. The mode of action by which botulinum toxin is effective in migraine prophylaxis is not fully understood and is under investigation. Currently, a number of other randomized, placebo-controlled, clinical trials are being conducted to evaluate the efficacy, optimal dosing, and side-effect profile of botulinum toxin type A in the prophylaxis of migraine and other headache entities.