Evidence-based medicine in botulinum toxin therapy for cervical dystonia

Early controlled studies of botulinum toxin (BTX) in cervical dystonia were unblinded and indicated that BTX injections are more successful than medication. In this article, the use of botulinum toxin (BTX) in cervical dystonia is reviewed according to evidence-based medicine. To document the efficacy of BTX, there have been a number of prospective, placebo-controlled studies of the use of BTX in cervical dystonia. Most were double-blind, some included videotapes to provide blinded objective assessments. The more recent studies of BTX in cervical dystonia focused on particular issues such as utility of EMG guidance, comparison to anti-cholinergic treatment, BTX serotype B in BTX type A resistant and non-resistant patients and different dosages. Despite the wealth of data generated with prospective placebo-controlled studies on the effectiveness of BTX in cervical dystonia, there is uncertainty on which outcome measures to use to express the efficacy of treatments for cervical dystonia. Disease specific instruments to measure quality of life in cervical dystonia have not been used so far. Data on the use of BTX for cervical dystonia have long been restricted to small series of patients reflecting exclusively the experience of individual specialized centers.