Sydenham's chorea is a childhood movement disorder. Thomas Sydenham, after whom the condition is named, first described it in 1686. The word 'chorea' comes from the Greek word for 'to dance'.
What are the symptoms of Sydenham's chorea?
The main symptom is that the child makes movements that are described as 'rapid, irregular, aimless and involuntary'. These movements can affect the muscles in the limbs, face and trunk. Sometimes other effects appear alongside the movements, such as muscle weakness, poor muscle tone and clumsiness. The movements seem to vary in intensity, and the area they affect may change over time. The overall effect of the movements is that the child seems to be twitching constantly.
This may start in a relatively subtle way and change over a period of weeks, but for some children, it lasts a bit longer, for a year or two. Another difficulty is that the child may have changes in their feelings or behaviour. He or she may develop worries that they never had before or feel the need to carry out certain repetitive actions or rituals (compulsions) because they have thoughts or impulses to do these things (obsessions). Sometimes, he or she may feel sad or worried about how to tell other people about the movements. This may make some children feel irritable or angry. They may also have mood swings.
How is Sydenham's chorea diagnosed?
Sydenham's chorea is often diagnosed by asking questions, examining the child and hearing how the condition happened. There is no specific test for Sydenham's chorea.
What causes Sydenham's chorea?
It most often occurs following a sore throat, caused by a germ called streptococcus. However, only a few strep throat infections lead to Sydenham's chorea. The bug causes a change in the chemicals in the area of the brain controlling movement. The sore throat usually clears up but the movements start to appear between six weeks and a few months later. It rarely appears longer after the infection has disappeared.
As well as the sore throat, the infection can also affect other areas of the body, such as the joints and heart. The doctor will carry out various tests and examinations to check that they are not affected. Sydenham's chorea can also follow infection with rheumatic fever or scarlet fever.
How common is Sydenham's chorea?
It affects a small number of children each year in the UK. More girls than boys seem to develop the condition, but we do not yet know why this should be the case. It is most common in children aged between five and 15 years old.
How can Sydenham's chorea be treated?
It is usually treated with a medicine called haloperidol although antibiotic treatment, often with penicillin, may be used to get rid of the streptococcus germ. The usual course of antibiotic treatment is much longer than usual, as the aim is to stop the infection coming back again.
Some doctors recommend taking antibiotics for five years, although some think that a child should take them for the rest of his or her life. Sometimes, the movements may stop by themselves although this can take months or even up to two years.
What is the outlook for children with Sydenham's chorea?
The future is good, and children frequently recover completely. It is very important for children with Sydenham's chorea to work hard at returning to school and the sorts of normal everyday activities they used to enjoy. Explaining to teachers and classmates can often make returning to school easier. Sometimes, the return to school and activities may need to be built up gradually as he or she starts to feel better again.