Treatment of headache with botulinum toxin A--a review according to evidence-based medicine criteria.

The aim of this review is to evaluate the studies available from reference systems and published congress contributions on the prophylactic treatment of idiopathic and cervicogenic headache with botulinum toxin A, and to classify these studies according to evidence-based medicine (EBM) criteria. The studies were analysed with respect to the study design, the number of patients enrolled, the efficacy parameters, and the significance of results. We used the following classification of EBM. I: randomized, controlled study with sufficient number of patients; II: well-designed, controlled study (or randomized, controlled study with insufficient number of patients, no exact diagnosis, missing data of botulinum toxin A dose); III: well-designed, descriptive study; IV: case reports, opinions of experts. For tension-type headache, two studies were found with negative evidence of I with respect to the primary endpoint. There are about as many positive as negative studies with evidence of II or III. For the therapy of migraine, one study with both negative and positive evidence of I, one in part positive study of II, and three positive studies classified as III are available. Two studies on cervicogenic headache with evidence of II and III are contradictory. In addition, we found several positive case reports. For patients with cluster headache, there are positive and negative case reports. We found one positive case report for the treatment of chronic paroxysmal hemicrania. As a result of this analysis, we consider no sufficient positive evidence for a general treatment of idiopathic and cervicogenic headaches with botulinum toxin A to date. Further studies are needed for a definite evaluation of subgroups with benefit from such treatment.