Thuốc Dysport® điều trị Lâu Năm cho Bệnh Rối Loạn Trương Lực Cổ
DYSPORT®in the Long Term Treatment of Cervical Dystonia
Bs Daniel Trương, M.D., Chuyên Khoa Bệnh Thần Kinh
The Parkinson’s and Movement Disorder Foundation
(Quarterly Newsletter –Spring 2010)

Cervical dystonia, also known as spasmodic torticolis, in the most common focal dystonia, affecting as much as 0.4% of the population. Most patients with cervical dystonia experience at least some disability, as many as 50% experience difficulty related to their employment because of their symptoms. Treatment with botulinum toxin is recommended as the first line strategy for patients with cervical dystonia. There are several different types of botulinum toxin.
Botulinum toxin type A has been the most studied type for neurological disorders, including cervical dystonia. In adding to relaxing affected muscles and reducing the force of the muscle contraction, treatment with botulinum toxin has been reported to decrease pain and to improve range of motion and resting posture.
The effectiveness of botulinum toxin is time-limited, and the symptoms eventually return and require additional injections. Given that patients with cervical dystonia will need repeated injections of botulinum toxin over time, it is important to understand its long-term safety and efficacity. I and other physicians from around the world conducted a study to address this question with Dysport®, one specific formulation of botulinum toxin type A. The results were recently published in the journal Parkinsonism and Related Disorders.
The study had two parts. The first part was a 12-week study to test the safety and efficacity of Dysport® for treatment of cervical dystonia. Here the patients were assigned to different treatment groups randomly – like the flip of a coin. Some patients got injections with Dysport® (500U) and others got injections of placebo, an inactive substance.
In the second part of the study, all patients were treated with Dysport®. There were 116 patients in the first phase of the study, 55 in the Dysport® group, and 61 in the placebo group. Of those, 108 started the open labeled phase. Some patients got all 4 injections during this phase, whereas others got 3, 2, or 1, depending on their medical need.
The results of the first part of the study showed that Dysport® improved symptoms of cervical dystonia at week 4 of treatment. The improvement of symptoms was still apparent at week 12 of treatment. Treatment with Dysport® also significantly reduced pain and disability.
During the second part of the study, subsequent treatments with Dysport® continued to produce improved symptoms. Although the greatest improvement was observed after the first open-label treatment, all treatments improved symptoms. These results show that Dysport® is effective even after long-term treatrment.
Dysport® was also safe and well tolerated after long-term treatment. The most common side effect in both parts of the study was difficulty swallowing. Most side effects were mild or moderate.
Cervical dystonia is a life-long condition for which there is no cure. At the present time, the recommended first-line treatment is botulinum toxin. Because there is the potential for patients to require botulinum toxin for many years, it was important to demonstrate that it is effective and safe over long term use. Although this study only explored the effects of at most five doses (one in the first part of the study and up to four in the second part), patients were in the study for an average of one year because there was an average of 15-17 weeks between doses. Longer studies will be needed, as will studies other formulations of botulinum toxin type A as well as other toxin types. However, this study was the longest of its kind and the results are very encouraging.

Daniel Truong, M.D.
The Parkinson’s and Movement Disorders Foundation
www.pmdf.org

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