Botulinum toxin type A versus anticholinergics for cervical dystonia

Abstract

Cervical dystonia is the most common form of focal dystonia. It is characterized by involuntary posturing of the head and frequently is associated with neck pain. Disability and social withdrawal are common. Most cases are idiopathic and generally cervical dystonia is a life-long disorder. Botulinum toxin Type A (BtA) is now the first line therapy. Before BtA, anticholinergics were the most widely accepted treatment, so it is important to understand how these two treatments compare. To compare the clinical efficacy and safety of BtA versus anticholinergic drugs in the treatment of cervical dystonia. We searched the Cochrane Movement Disorders Group trials register (June 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2, 2003), MEDLINE 1977 to June 2003), EMBASE (1977 to June 2003) and reference lists of articles. We also contacted manufacturers and researchers in the field. Randomised studies comparing BtA versus any anticholinergic drug for the treatment of cervical dystonia. Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials. We found only one trial suitable for inclusion and accordingly no meta-analysis was performed. It compared BtA versus trihexyphenidyl in 66 patients with cervical dystonia. Although this was a relatively small trial with short duration, the results can probably be generalized for the population, since the trial appears to be unbiased and produced clear clinically significant results. The results favoured BtA, and the difference was similar in size to that obtained in a systematic review comparing BtA with placebo. BtA was better tolerated. The available evidence suggests that BtA injections provide more objective and subjective benefit than trihexyphenidyl to patients with cervical dystonia. We could not draw any conclusions about other anticholinergic drugs. Future trials should explore the role of anticholinergic drugs in patients that do not get benefit with BtA.