Evidence-based medicine: botulinum toxin A in migraine and tension-type headache

The therapeutic effect of botulinum toxin in headache was observed coincide ntally. The rationale for this new indication initially met with a great de al of scepticism, because the toxin's mechanism of action, cholinergic chem odenervation, does not fit the pathophysiological concept of migraine and o ther forms of headache. Meanwhile a fair number of studies have been publis hed which indicate efficacy for botulinum toxin and recommend its use for t he treatment of tension headache and migraine. According to the evidence-ba sed medicine criteria, grade I evidence has been demonstrated. In addition the use of botulinum toxin for cluster-headache and secondary headache is d iscussed. Further large scale studies will be regarded to demonstrate the long-term e fficacy.