Sydenham chorea (SC) is a childhood neurological disorder. It is a potential complication of a group A strep infection and causes physical and behavioral changes.
In this article, we will discuss what SC is, its symptoms, complications, treatment, and its relation with PANDAS and Huntington’s disease.
According to the National Institute of Neurological Disorders and Stroke Stroke (NINDS), SC is a neurological disorder that only affects children.
Healthcare professionals characterize SC by sudden onset chorea, which they define as the random appearance of involuntary movements while someone is awake. These movements can affect the entire body.
SC is a complication that can develop during or after an infection with the bacteria, Group A beta-hemolytic streptococcus (GABHS), which can also cause rheumatic fever.
This condition is very rare in North America and Europe due to infection control and the wide availability of antibiotics that treat streptococcal infections and rheumatic fever.
NINDS indicate that SC appears to affect girls more than boys, most commonly between the ages of 5–15.
Most children recover completely from SC, and the symptoms last between 3–6 weeks, although some may continue for several months.
According to a 2017 review, SC symptoms typically occur 4–8 weeks after infection with GABHS.
Symptoms of SC may develop suddenly or gradually during or shortly after an infection, but can also appear 6 months or longer after the infection and fever have cleared.
Healthcare professionals divide SC symptoms into neurological types, which usually involve movement and balance, and neuropsychiatric symptoms that affect behavior and cognition.
According to one article, SC neurological symptoms include:
- erratic, involuntary, movements, mainly of the shoulders, hips, and face
- being unable to remain in a steady position
- jerky eye movements
- reduced muscle tone
- motor tics
- difficulty pronouncing words
According to the National Organization for Rare Disorders (NORD), the jerky movements are typically worse on one side of the body.
SC neuropsychiatric symptoms can include:
- rapid mood changes
- being easily distracted and irritable
- age-regression, going back to a younger state of mind
According to a 2020 article, SC is an autoimmune response to the infection. The bacteria induce the body to make antibodies to fight the infection.
However, once the antibodies have beaten the infection, they can remain active for too long and mistakenly attack healthy parts of the body. When the antibodies attack the basal ganglia cells in the brain, symptoms of SC can develop.
According to NORD, researchers do not know precisely why these antibodies attack the brain. They believe that GABHS antigens, the part of the bacteria that causes the body to produce antibodies, are very similar to the antigens in the basal ganglia.
There are three forms of treatment therapies.
If symptoms of SC appear, doctors may also prescribe additional medication to control the neurological and neuropsychiatric symptoms.
This may reduce the chance of neurologic disease and permanent heart valve damage.
According to the World Health Organization (WHO), some children should continue to take these antibiotics for several years, or in some cases, until adulthood.
Although the efficacy of symptomatic treatment requires more research, doctors may prescribe valproic acid to control distressing involuntary movements of SC.
An article in Tremor and other Hyperkinetic Movements indicates that children will typically start at a dose of 250 milligrams (mg) per day, increasing up to 1,500mg per day until the symptoms go away. Valproic acid takes up to 2 weeks to begin working.
For some behavioral and psychiatric symptoms, doctors may prescribe neuroleptics, which are tranquilizers.
Risperidone is a neuroleptic that helps control the jerky movements of SC. Usually, children take 1–2 mg of risperidone per day for a few weeks or months.
Another treatment option with fewer side effects is tetrabenazine, which is a dopamine depleting agent. However, healthcare professionals are not yet sure how effective it is.
Immune system treatment
Healthcare professionals may prescribe short-term immune therapies to help treat the autoimmune response during the first weeks.
Some experts theorize that ongoing acute inflammation is a contributing factor to symptoms.
However, there appears to be little research to provide evidence that it works.
SC is a complication of the same bacteria that can cause rheumatic fever. Because of this, there are several associated complications, including:
- joint arthritis
- joint pain
- inflammation of the heart valves leading to permanent damage
- ongoing fever
Symptoms of SC typically resolve within 3 weeks to 6 months.
However, although almost everyone recovers from SC, symptoms can persist for up to 2 years.
SC may return. According to NORD, young women in the first trimester of pregnancy have a higher chance of symptoms of SC recurring.
According to NORD, there are several risk factors for developing SC.
- Sex: SC typically affects girls more than boys.
- Age: It usually affects those between the ages of 5–15. However, it rarely affects those below the age of 5 or in adults.
- Rheumatic fever: Out of those who have rheumatic fever, 25% will develop SC.
There is no specific test that allows doctors to diagnose people with SC.
Instead, they will evaluate a person’s symptoms, including muscle movements and heart function.
Doctors may order blood tests to rule out other diseases and conditions that may cause similar symptoms.
Doctors may be able to diagnose the condition by looking at the basal ganglia. Although other conditions also affect the basal ganglia, SC works differently.
SC can have symptoms that are similar to PANDAS and Huntington’s disease.
PANDAS stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections.
According to the National Institute of Mental Health (NIMH), some PANDAS conditions include:
- obsessive-compulsive disorder (OCD)
- attention-deficit/hyperactivity disorder (ADHD)
- tic disorders
- personality changes
According to NIMH, doctors may diagnose a child with PANDAS when:
- OCD, tics, or both, appear after a strep infection, such as strep throat or scarlet fever
- OCD or tics get worse after a strep infection
Similarly to SC, the body reacts to a strep infection with antibodies that eventually attack the brain, mistaking it for bacteria. This causes OCD and tic behavior.
Just like SC, children with PANDAS may experience jerky, involuntary movements. Having a history of SC increases the chances that a child may develop PANDAS later.
According to NINDS, there is some evidence that children who have recurring SC are more likely to have PANDAS. However, researchers are not sure why this is the case.
Huntington’s disease causes some symptoms that are similar to SC. According to NINDS, they include:
- changes in behavior and emotion
- jerky movements
- slurred speech
However, unlike SC and PANDAS, Huntington’s disease is an inherited condition, and the symptoms typically begin during adulthood.
People who have Huntington’s disease have a mutation in a protein called huntingtin. This makes the protein toxic, which leads to the death of brain cells, or neurons. This is what causes the symptoms.
Unlike SC, there is currently no cure for Huntington’s. It is a progressive disease, and people who have Huntington’s disease often worsen rapidly. Most people with a diagnosis will live 10–30 years after the first symptoms appear.
NINDS state that most children will completely recover from SC, although some may experience persistent jerky movements despite treatment.
However, 33% of children will experience a return of symptoms 18–30 months after the first episode.
Some children may also experience a sudden onset of OCD, ADHD, tic disorders, and autism. A doctor may diagnose the sudden onset of these conditions as PANDAS.
SC is a neurological disorder that causes a range of physical and behavioral symptoms.
Children who contract rheumatic fever may later develop SC due to antibodies mistakingly attacking healthy cells.
The primary treatment for SC is antibiotics, and some children may need to take these antibiotics until they are adults.