​Sydenham's chorea

Sydenham's chorea (also known as St. Vitus dance, St. Johannis' chorea, chorea minor or rheumatic chorea) is a symptom of acute rheumatic fever. Rheumatic fever is an inflammatory disease that can permanently damage the heart. It is common in children between the ages of three and fifteen. Sydenham’s chorea is usually contracted during childhood and is a neurological disease (that is, related to the brain). It is a movement disorder, during which you suffer from involuntary muscle movements such as twitching, jerking, jumping or dancing. This disease affects the limbs such as forearms, hands, lower legs and feet. These movements are abrupt and irregular, and usually cease when you are sleeping.  

The incidence of rheumatic fever and Sydenham’s chorea has dramatically reduced over the years, particularly in the Western world but in developing countries there are still some cases. It occurs most often in pre-pubescent girls but is sometimes also known to occur in boys.