tDCS in Cervical Dystonia

Dystonia is a devastating disorder defined by involuntary, sustained muscle contractions or abnormal postures that can affect any part of the body. Cervical dystonia (CD) is the most pervasive form of dystonia affecting 60-90,000 individuals in the United States alone and is characterized by involuntary twisting of the neck. The symptoms of CD are disabling, disfiguring, painful, and have a strongly negative impact on quality of life, including social withdrawal and depression. At present, there is no treatment that has been shown to have long term benefit in CD. Standard of care (SOC) is botulinum toxin, which temporarily paralyzes affected muscles, resulting in reduced muscle spasms. This treatment has many undesirable side effects, variable effectiveness, is expensive, and must be repeated every 3 months throughout the lifespan. Physical therapy based treatments aimed at retraining posture or stretching dystonic muscles are largely ineffective and not typically delivered as a part of standard of care. There is an urgent need for novel and effective therapies. Emerging technologies, specifically non-invasive brain stimulation (NBS), have demonstrated compelling evidence to make a meaningful impact in the lives of people with CD. In this study, individuals with cervical dystonia will be randomly assigned to receive tDCS for 15 minutes daily for 4 days in 1 of 4 stimulation location groups. Hypothesis 1: One location of stimulation will result in clear benefit with at least 1 standard deviation (SD) improvement in the CDQ-24, the primary outcome measure, at 1-week follow-up. Hypothesis 2: The cortical silent period will be the most sensitive measure investigated and will demonstrate significant increase in inhibition as determined by an elongation of silent period in the affected upper trapezius muscle. Hypothesis 3: The stimulation location determined to be most effective in Objective 1 will produce the greatest physiologic change in inhibition increase. Hypoth