The purpose of this study is to evaluate the safety and effectiveness of daxibotulinumtoxinA for injection (a new investigational study drug) compared to placebo in the treatment of cervical dystonia (CD). DaxibotulinumtoxinA for injection is composed of purified botulinum toxin type A, formulated with a small protein RTP004, and will be used for injection. Placebo means it doesn't contain botulinum toxin type A.
If you are eligible and choose to be in the study, the dose of study drug you receive will depend on the group that you will be put into after randomization at the time of your entry.
You will be assigned, by chance, to 1 of the 3 groups below:
? Group 1: High-dose (250 Units of daxibotulinumtoxinA for injection)
? Group 2: Low-dose (125 Units of daxibotulinumtoxinA for injection)
? Group 3: Placebo (a substance that looks like daxibotulinumtoxinA for injection but has no drug in it)
Study lasts aproximately 39 weeks, including 3 weeks of screening. You will come to the study center up to 12 times during the research study.
The study is being done at approximately 80 sites. Approximately 300 people will take part study-wide and 4 will take part at this institution.
This study will examine changes in brain architecture that are associated with vascular parkinsonism, in comparison to Parkinson's disease. We will do this by using advanced imaging techniques to compare brain structure between subjects with vascular parkinsonism and Parkinson's disease.