engleski

Different Doses of Botulinum Toxin A and Pain Responsiveness in Cervical Dystonia

To investigate the effectivness of different doses of botulinum toxin type-A (BTX-A) in pain associated with cervical dystonia. Effectivness of BTX-A against pain associated with cervical dystonias has been established. However, the pain relief experienced usually outweighed the degree of motor benefit obtained. Several studies suggest that a direct antinociceptive effect distinct from reduction in muscle spasm may be involved. A study investigating the effect of three different doses of BTX-A on pain in cervical dystonia has not been published previously. We have studied thirty-one patients with painful cervical dystonia, 18 female/13 males with age range 24-63 years. The patients baseline level of pain and the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) were assessed. In addition, patients kept home diary to investigate pain severity (scale from 0-3) and pain frequency (graded on a scale of 1-5). Using a randomized, double-blind, cross-over design (three treatment periods of 4-month duration) we injected patients with tree different doses of BTX-A (50, 100, and/or 150 U of BOTOX) in the most affected musles. Clinical assessment and home diary registration were performed each week during the 12-month study. Side effects were monitored during the study. Significant pain relief (p<0.05) was obtained in patients during each treatment period (50, 100 and/or 150 U of BOTOX) already one week after injection. On the contrary, TWSTRS-Total Score was significantly (p<0.05) decreased after at 2 weeks post injections, but only during two-treatment periods when higher doses of BTX-A was used (100 and 150 U of BOTOX). Thus, the smallest dose of BTX-A used (50 U of BOTOX) significantly reduced pain without any change in muscle activity and TWSTRS. In addition, with two higher doses of BTX-A (100 and 150 U of BOTOX) pain relief was obtained one week post injections while it took 2 weeks for significant reduction in TWSTRS score. No systemic side effects were noted. Injection of BTX-A results in significant improvment of pain associated with cervical dystonia. The major benefit of BTX-A treatment on pain reduction compared with dystonia improvement was the duration of action and the lower beneficial dose. These results appear to demonstrate for the first time that BTX-A may have a direct antinociceptive effect distinct from influence on the muscle-relaxing properties.

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