Introduction

Definition of sydenham chorea

Sydenham Chorea is a rare neurological disorder that is identifiable by chorea.¹ Chorea is defined as a movement disorder where there are random, involuntary muscle movements.² The word “chorea” comes from the Greek word “chorieia”, which means “to dance” due to the movements the patients make that seem like they are dancing.³ Sydenham chorea is associated with rheumatic fever and is caused by A beta-hemolytic streptococcus infection.¹ 

In patients suffering from Sydenham Chorea, there may be involuntary movements affecting the entire body, but they are most common in the face, tongue, arms, and legs.¹ 

Sydenham Chorea occurs in children following A beta-hemolytic streptococcus infection that causes strep throat and rheumatic fever.² It is less common than it was in the past, and if it does occur, the symptoms will be less severe than before.⁴ Sydenham chorea is more likely to affect children who are 5-15 years old and more common in people assigned female at birth (AFAB).² 8 to 9 years old have the highest incident rate and is quite rare for Sydenham chorea to affect adults.⁴ Most cases of Sydenham Chorea occur in developing countries due to higher beta-hemolytic streptococcus infection and less effective treatment of streptococcus infection.⁴ The situation is made worse by poor hygiene and overcrowding.⁴ 

Historical background

Chorea was described as early as the Middle Ages when a ‘dancing mania’ epidemic was spreading in Europe.⁵ It was thought to be a curse by Saint Vitus, and individuals were cursed if they touched churches containing Saint Vitus’s relics.5 It was not until 1686 that Thomas Sydenham provided an accurate clinical description of acute chorea, but it was not until 1850 that Sydenham's chorea was related to rheumatic fever.⁵ 

Causes and pathophysiology

Sydenham chorea occurs following Group A beta-hemolytic streptococcus infection that causes strep throat and rheumatic fever.² 

Rheumatic fever as a precursor

In 40% of patients suffering from rheumatic fever, they develop Sydenham chorea.⁴ Rheumatic fever is a condition that occurs after a Group A streptococcus infection that causes strep throat or scarlet fever.⁶ Rheumatic fever causes inflammation of the heart, joints, brain, and skin, but it is easily treatable with antibiotics and anti-inflammation medicine.⁶ 

Autoimmune mechanism

Group A beta-hemolytic streptococcus infection causes an abnormal immune response where the immune system attacks the basal ganglia cells within the central nervous system (brain) when stimulated by the presence of the Group A Beta-hemolytic streptococcus bacteria.⁴ This means that Sydenham chorea is an autoimmune disorder as the immune system mistakenly attacks the brain instead of the bacteria.¹ The targeting of the brain and the central nervous system is what causes the irregular motor movement and causes the symptoms of Sydenham chorea.¹ 

Infection connection

The exact cause and mechanism that causes Sydenham's chorea is not fully understood.1 Current research shows that the antibodies produced by the immune response against the streptococcus bacteria interact and react with the ganglia cells, which are crucial for controlling motor movement⁴. When the ganglia cells are damaged, chorea will be observed in patient leading to Sydenham chorea being diagnosed.⁴

Clinical presentation

Symptoms of chorea can affect anywhere in the body and can be delayed after the streptococcus infection². It can be up to 6 months after developing strep throat or rheumatic fever that you or your child can develop Sydenham chorea.² Symptoms of Sydenham chorea are:

1. Motor symptoms
2. Non-motor symptoms.

Motor symptoms

Motor symptoms are symptoms that affect your movement and balance, and these include:

• Involuntary limb movements (chorea)¹
• Clumsiness²
• Restlessness²
• Loss of motor control¹
• Facial grimacing¹
• Stumbling and falling²
• Muscle weakness²

Involuntary movement is a clear sign of Sydenham's chorea, which can affect all four limbs (both arms and legs).4 These involuntary movements can range from subtle movements to severe movements, which can affect performing basic tasks.1 Chorea can change throughout the day, but in most cases, chorea stops during sleep.¹

Non-motor symptoms

Patients can also suffer from behavioural changes and emotional disturbances. These include:

• Speech issues such as slurred speech or vocal outbursts²
• Anxiety²
• Difficulty concentrating²
• Obsessive-compulsive disorder
• Vocal tics⁴
• Hyperactivity and attention deficit disorder have been observed⁴

Behavioural problems are common with Sydenham chorea patients, with up to 70% of patients suffering from obsessions and compulsion disorder. Hyperactivity and attention deficit disorder have been found in 45%.⁴ In some rare cases, patients have severe muscle weakness, are irritable or have high levels of confusion, causing affected children to become bedridden, but this affects less than 2% of Sydenham chorea patients.¹

Fortunately, most children completely heal from Sydenham chorea.⁷ Sydenham chorea symptoms usually clear after three weeks to six months, but in rare cases, some symptoms can last longer than a year and can also reoccur during adult life.¹

Diagnosis

There is no specific test available that can provide a definitive diagnosis of Sydenham chorea.¹ Instead, diagnosing Sydenham chorea is dependent on identifying chorea movement, medical history symptoms and the potential exposure to beta-hemolytic streptococcus using laboratory testing.² 

Medical history and physical examination

Chorea movement is observed and examined by a doctor to determine if movement is involuntary. Medical history of previous streptococcus infection is also determined, especially a history of rheumatic fever or strep throat. All patients will also need neurological and cardiac evaluation. Echocardiogram is used to determine if a patient has carditis (inflammation of the heart muscles) as 80% of patients with Sydenham chorea suffer from an existing cardiac disease². Neuroimaging is also done using magnetic resonance imaging (MRI) to rule out other diagnoses¹. Brain imaging is normal in patients with Sydenham chorea.¹

This is not enough to diagnose Sydenham's chorea and is accompanied by laboratory testing.  

Laboratory tests

Diagnostic tests are done to determine previous streptococcal infections. This is done through:

• Antistreptolysin O (ASO) Titer

ASO titre is a blood test to measure antibodies present in the blood that is against streptolysin O.⁸ Streptolysin O is a toxic that is produced by the beta-hemolytic streptococcus bacteria and our immune system produces antibodies against the toxins.⁹ A positive test result will show that you have a recent history of streptococcus infection, even if you did not present any symptoms.⁸

• Erythrocyte sedimentation Rate (ESR)

ESR is another blood test done that measures inflammation activity in the body.¹⁰ It can be used to determine rheumatic fever which is associated with Sydenham chorea.¹ 

• C-reactive protein (CRP)

CRP is a blood test that also measures the level of inflammation in the body.¹¹ C-reactive protein is a protein that is made by the liver, and protein production is increased when there is inflammation in the body.¹¹ A positive test of CRP will mean there is inflammation in your body, but it can not be used to determine the cause of the inflammation.¹¹

Differential diagnosis

Sydenham chorea shares signs and symptoms similar to other disorders.¹ These could be movement disorders, psychiatric conditions and other rheumatic fever complications.

Other movement disorders

Movement disorders can include:

• Parkinson’s disease
• Huntington disease
• Multiple system atrophy

Psychiatric conditions

When psychiatric medicine is started, altered or stopped, patients may begin to develop chorea.¹ Medicine prescribed for conditions such as: 

• Schizophrenia¹⁴
• Bipolar disorder¹
• Tourette syndrome¹

Other rheumatic fever complications

Some chorea are caused by other autoimmune disorders that cause inflammation¹. Examples are:

• Lupus⁴
• Multiple sclerosis⁴
• Behcet disease⁴

Treatment and management

Treatment and management of Sydenham chorea will depend on the symptoms you or your child has and how severe the disease is.² In most cases, Sydenham chorea is mild and will not require treatment.² There are several types of treatment available for treating Sydenham chorea:

1. Medicinal intervention
2. Management of rheumatic fever.

Medicinal intervention

Medicine is used in individuals who have moderate symptoms. There is no medicine that targets Sydenham chorea itself, and these medicines are used for other conditions, but they are safe to use.² They include:

• Anticonvulsant medicine like valproic acid and carbamazepine. These drugs work by limiting the overaction of neurons in your body.
• Anti-psychotic medicine like haloperidol. This medicine works by blocking nerve activity in the brain.¹² 
• Dopamine depleters like Tetrabenzine. Tetrabenazine is used to treat chorea, and it works by preventing the central nervous system from absorbing chemicals like dopamine.¹³

Management of rheumatic fever

Short-term immune therapies are available that target the inflammation which causes the symptoms of Sydenham Chorea.¹ These include:

• Oral corticosteroids like deflazacort. Corticosteroids are used to treat the inflammation caused by rheumatic fever and showed effective treatment with few side effects.¹⁴ 
• Anti-inflammatory drugs such as aspirin are also used to reduce inflammation caused by rheumatic fever.² 

Prognosis

 The prognosis of patients with Sydenham chorea will depend on the symptoms the patient has. Fortunately, Sydenham chorea fully recovers in everyone except the rare exceptions.⁴ Recovery is expected in most cases to take between three to six months.²

In 2% of Sydenham chorea cases, some symptoms can reoccur again in their adult life, and some symptoms may persist for more than two years.⁴

Prevention

Sydenham chorea can be prevented by taking the right treatment for strep throat and rheumatic fever.² Treating the Group A beta-hemolytic streptococcal infection is crucial in preventing the development of rheumatic fever, which could then show symptoms of Sydenham chorea.⁴

If you or your child has been diagnosed with Sydenham chorea, doctors may prescribe antibiotics against streptococcal infection until they reach adulthood, and this is to prevent streptococcal infection from occurring again.² By preventing the recurrence of the streptococcal infection, it would prevent rheumatic fever, which would then prevent Sydenham chorea from resurfacing again.²

Conclusion

Sydenham chorea is a neurological disorder caused by an autoimmune response against Group A beta-hemolytic Streptococcus infection. Patients develop this disorder following strep throat infection or rheumatic fever.² Symptoms include involuntary movement, loss of motor control, muscle weakness and behavioural changes.²

Diagnosing Sydenham chorea is difficult and relies on an interdisciplinary team of neurologists, immunologists, cardiologists, pharmacists and nurses to identify the disorder.⁴ In some cases, the symptoms may last longer than two years and recurrence of Sydenham chorea is a risk that also has to be managed. 

Preventing Sydenham Chora by treating Group A beta-hemolytic streptococcal infection is highly effective, and treating Sydenham Chora patients with antibiotics to prevent recurrence is recommended by the WHO until the patient has reached 21 years.⁴ Prognosis of Sydenham chorea is dependent on the symptoms of the patient, but the majority of patients recover from this disorder.²