What is Sydenham’s Chorea?

Sydenham’s Chorea (also known as St Vitus Dance or Chorea Minor) is a disease affecting the brain. It happens after a childhood infection, due to a problem with the body’s immune response to a common infection. The infection is caused by a bacterium called Streptococcus. In certain individuals, for reasons which are unclear, the immune system reacts in an unusual way to this infection. This produces a response that interferes with cells in parts of a child’s brain called the basal ganglia. The basal ganglia are collections of brain cells located deep within the brain which have a role in controlling movement and emotional responses.

Sydenham’s Chorea usually develops up to six months after a child has suffered a Streptococcal infection. Not all children have a clear history of having had a Streptococcal infection.

Most people who develop Sydenham’s Chorea do so before the age of eighteen. It is more common in girls than boys.

Sydenham’s Chorea can occur as part of a wider inflammatory response called Rheumatic Fever, which involves other parts of the body including the skin, joints and heart.