Efficacy of pharmacological treatment of dystonia: evidence-based review including meta-analysis of the effect of botulinum toxin and other cure options

The treatment of both generalized and focal dystonia is symptomatic. There is no evidence-based information about the efficacy of the different methods of the pharmacological therapeutic options currently being applied in dystonia. The specific questions addressed by this study were which treatments for dystonia have proven efficacy and which of them have unproven results. Following evidence-based principles, a literature review based on MEDLINE and the Cochrane Library, augmented by manual search of the most important journals was performed to identify the relevant publications issued between 1973 and 2003. All articles appearing in the professional English literature, including case reports, were considered. In the presence of comparable studies the meta-analysis was performed to obtain pooled information and make a reasonable inference. Based on this review, we conclude: (i) botulinum toxin has obvious benefit (level A, class I-II evidence) for the treatment of cervical dystonia and blepharospasm; (ii) trihexyphenidyl in high dosages is effective for the treatment of segmental and generalized dystonia in young patients (level A, class I-II evidence); (iii) all other methods of pharmacological intervention for generalized or focal dystonia, including botulinum toxin injections, have not been confirmed as being effective according to accepted evidence-based criteria (level U, class IV studies).