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Botulinum toxin for cervical dystonia

Cervical dystonia is characterised by involuntary posturing of the head, and is frequently associated with neck pain. Botulinum toxin injections have become common for this condition, and four recent Cochrane reviews have looked for the evidence. The topic is complicated by the fact that there are two different forms of the toxin, type A and type B.

Botulinum toxin type A


J Costa et al. Botulinum toxin type A therapy for cervical dystonia. Cochrane Database of Systematic Reviews 2005 Issue 1.


Clinical bottom line

There were 13 randomised (510 patients), blinded studies comparing Botulinum toxin type A with placebo. Studies were of short term, of six to 16 weeks. Two different commercially available forms of toxin were used, with different doses. Subjective patient assessment of improvement was better for Botulinum toxin A (59%) than placebo (20%; Figure 1). The relative benefit was 3.0 (2.3 to 4.0), and the number needed to treat for one additional patient to have subjective improvement was 2.5 (2.1 to 3.1). Neck weakness, dysphagia, dry mouth, sore throat, and voice changes tended to be more frequent with Botulinum toxin.

Figure 1: Subjective improvement in clinical trials at six to 16 weeks


Botulinum toxin type B


J Costa et al. Botulinum toxin type B for cervical dystonia. Cochrane Database of Systematic Reviews 2004 Issue 4.


Clinical bottom line

There were three randomised (308 patients), blinded studies comparing Botulinum toxin type B with placebo. Studies were of short term, of six to 16 weeks. A variety of doses were used. There were consistent benefits with Botulinum toxin B compared with placebo for pain. Dysphagia and dry mouth were common adverse events.