A standardized clinical instrument designed to measure the presence, severity, anatomical distribution, and functional impact of involuntary, chaotic movements known as dyskinesias. It is especially widely used in Parkinson’s disease, where dyskinesias often occur as a side effect of long-term dopaminergic therapy (primarily levodopa). The scale can include both a physician’s assessment and patient self-reports, allowing for a quantitative assessment of movement disorders and informed decisions to adjust therapy, including the possibility of surgery, such as deep brain stimulation.