Choreic movements are rapid, purposeless, flowing motor jerks. They result from dysfunction or damage of deep brain structures, usually the caudate nucleus, putamen, subthalamic nucleus, thalamus, or their interconnecting pathways. The prototypical neurodegenerative chorea is Huntington's disease. Chorea may occur in neurodegenerative diseases, may follow structural damage to the brain, or may be seen as a feature of medical illness, metabolic derangement, or a side effect of drugs. Drugs that increase dopamine or block acetylcholine may cause chorea, and drugs that block or deplete brain dopamine are most often used to control these involuntary movements.