Sydenham's Chorea

Synonym: St Vitus Dance.

Thomas Sydenham described chorea in 1686 in a work entitled Schedula monitoria de novae febris ingressu but it was not until 180 years later that the association with rheumatic fever was appreciated by Roger in 1866. Chorea comes from the Greek word meaning "dance".

The Jones criteria for the diagnosis of rheumatic fever originated in 1944¹ but it was not until they were revised in 1992² that Sydenham's chorea became a diagnostic feature.

• About 10 to 20% of patients with rheumatic fever develop chorea.
• It tends to present between the ages of 5 and 15 with a female preponderance of 2:1 or greater.
• A predisposition runs in families.
• It occurs most often in pre-pubertal girls.
• The incidence of Sydenham's chorea reflects that of rheumatic fever. It is rarely seen in developed countries nowadays. In developing, especially tropical countries, the rate is much higher but with much variation and often poor recording.
• Both primary and recurrent episodes are equally common.

Risk factors

Overcrowding and poor hygiene are important. As with rheumatic fever there is a risk of heart disease that is more common in females.

It often presents with other features typical of rheumatic fever, at least on the first occasion but it can present in isolation, especially if it is a repeat attack. The revised Jones criteria allow for chorea alone to be a diagnostic feature of rheumatic fever. Features of chorea are:

• Involuntary movements
• Hypotonia
• Muscular weakness
• Psychological features

Children are often confined to bed or are unable to attend school during the illness.

Movement Disorders

• Chorea is an involuntary and random movement such as an arm flying up. This is worse when "under pressure". The child may try to convert this into an apparently purposeful movement by pushing back her hair or scratching her nose.
• The chorea appears unilateral in about 20% but careful examination will often show milder features on the other side.
• It involves the extremities and the face and they may be accused of "making faces". Movements occur at rest and disappear in sleep.
• Chorea interferes with voluntary movements and causes a clumsy gait, dropping and spilling, and explosive bursts of dysarthric speech.
• Ask her to extend her arms and spread her fingers. Her fingers will move in a way like playing the piano. Muscular weakness leads to inability to maintain a steady grip. Ask her to grip your hand or wrist tightly and maintain it. The fluctuating strength of the grip is called "milkmaid's grip."
• The "pronator sign" is hyperpronation of the hands, with the palms facing outward when the arms are held over the head.

Psychological Symptoms

Psychological symptoms precede chorea and may be relapsing and remitting. They include:

• Emotional lability
• An obsessive trait
• Cognitive defects
• Personality change
• Motor hyperactivity
• Poor attention span

An examination of 8 girls and 3 boys found that 9 (82%) of the children had obsessive-compulsive symptoms whilst 4 (36%) met the diagnostic criteria for obsessive-compulsive disorder.³

Many of the laboratory features of rheumatic fever may be absent, especially if the onset of the disease was a significant time after the streptococcal infection and rheumatic fever may not have been apparent. Chorea lags between 1 and 6 months behind the streptococcal infection. There is no single diagnostic test. Other causes of chorea need to be excluded and often the diagnosis is one of exclusion in a child of the appropriate age.

• By the time that chorea presents it is unusual to be able to isolate a Lancefield group A beta haemolytic streptococcus from the pharynx.
• Blood count may be normal and ESR and CRP returned to normal.
• ASO titre and other serological tests described with rheumatic fever may still be helpful.
• Antineuronal antibodies have been described⁴ but they do not form part of routine diagnosis. The antibody titre falls as the disease improves and rise again in relapse.
• MRI studies have shown enlargement of caudate, putamen, and globus pallidus in patients with the disease⁵ and changes in the basal ganglia that resolved 2 weeks later.⁶

None of these is a normal diagnostic criterion.

This is a descriptive rather than an aetiological diagnosis. It simply refers to chorea in pregnancy.

• Most cases are a resurgence of Sydenham's chorea in the hormonal milieu of pregnancy.
• It can sometimes be precipitated by oral contraceptives.
• Back in the 1930s, at least 35% of patients had a definite history of acute rheumatic fever or Sydenham's chorea and 4% of those with chorea gravidarum had acute rheumatic fever.⁷
• Uneventful pregnancies before rheumatic fever have been followed by chorea in subsequent pregnancies.^{8 9}
• Carditis was found in 87% of fatal cases.⁷
• If left untreated, the disease resolves in 30% of patients before delivery but in the other 70% it persists until the puerperium.
• Symptoms often fade rapidly in the days after delivery. In some patients, neurological symptoms may continue with various degrees of incoordination, tremor, and clumsiness.
• Death is now rare but the mortality rate in the 1930s was 12% due to underlying rheumatic heart disease.
• In view of the current rarity it is difficult to assess the rate of fetal loss in this condition but it does not seem excessive.
• 21% have recurrent chorea with subsequent pregnancies.⁷
• Several cases have been described in which attacks occurred in 3, 4, and even 5 pregnancies.^{10 11}
• A paper written in 1900⁸ gave the incidence as 1 in 300 deliveries. Now it is regarded as an extreme rarity, reflecting the vastly reduced incidence of rheumatic fever, perhaps along with the treatment of the streptococcus.

• In the 1930s, if a doctor saw a patient with chorea, especially if the patient was a child or young woman, it was a reasonable assumption that the diagnosis was Sydenham's chorea. In western societies today, such a presentation is unlikely to be Sydenham's chorea and considerable thought must be given to the differential diagnosis.
• Huntington's chorea presents most often between the ages of 35 and 45 but it can be younger, especially if inherited from the paternal line. There is usually but not invariably a family history. A juvenile form exists that should be seen as a variation of the normal form and not a distinct entity.¹²
• Benign hereditary chorea¹³ starts in childhood, and is a non-progressive chorea. Inheritance is usually autosomal dominant, although rare cases of autosomal-recessive and X-linked inheritance have been reported.
• Wilson's disease is an autosomal recessive disorder of copper metabolism.
• Various paroxysmal dyskinesias need to be considered.
• A number of drugs can cause extrapyramidal effects of which metoclopramide, phenothiazines and haloperidol are the most important.
• Systemic lupus erythematosus
• Herpes simplex encephalitis
• Primary and metastatic brain tumours
• Various toxins especially carbon monoxide, manganese and organophosphate poisoning.

• Rest is usually required and traditional teaching is that this reduces the risk of rheumatic heart disease but controlled trials are lacking.
• A number of drugs may help control the chorea although many of these can have extrapyramidal effects of their own. Probably the best documented of these is haloperidol that has been available for many years but valproate would seem preferable.^{14 15}
• There may well be rheumatic carditis and possible involvement of valves, especially the mitral valve.¹⁶
• The treatment of cardiac complications or recurrent attacks with the need to eradicate streptococci is discussed in rheumatic fever.

• Symptoms generally improve in a week or two and are better inside 3 to 6 months, rarely lasting a year but occasionally they wax and wane over anything up to 10 years.
• There is evidence that despite apparent recovery that a degree of minor neurological impairment remains with an abnormal EEG but not behavioural problems.¹⁷
• About 20% of patients have a recurrence, usually within 2 years of the initial attack. About a third develop heart disease.¹⁸

Many of the references given here are listed not so much to be read as to indicate how old is much of the literature. A very considerable amount is from the first half of the 20th century when the requirements for publication were rather different from today but, more especially, the disease has changed. Not only is the disease substantially less common than it was but symptoms may well be less severe and relapses less frequent. This is supported by a paper from 1976¹⁸ that reviewed a declining number of cases from 1951 to 1976. This may be due in part to penicillin but also to improved social conditions and a natural reduction in the virulence of the streptococcus.