Sydenham's chorea (St. Vitus' dance): causes, symptoms, diagnosis, therapy, prognosis, recurrences
Sydenham’s chorea is a type of encephalitis that appears in individuals with rheumatic diseases, past or present, usually in childhood
It is one of the possible sequelae of an infection with the bacterium streptococcus pyogenes (also called ‘group A β-haemolytic streptococcus’).
It is characterised by rapid uncoordinated jerking movements (chorea) that occur mainly in the face, hands and feet.
The disease is usually latent and shows up to 6 months after acute infection, but may occasionally be the presenting symptom of rheumatic fever.
Sydenham’s chorea is also called ‘chorea minor’ or ‘infectious chorea’ or ‘rheumatic chorea’ or ‘St. Vitus’ dance’
The name of the disease originates from its discoverer, the English physician Thomas Sydenham (1624-1689). The eponym ‘St Vitus’ dance refers to the saint of the same name, who was persecuted by the Roman emperors and died a Christian martyr in 303 A.D., the patron saint of dancers.
Prolonged dances historically take place in front of his statue during the feast of St. Vitus in Germanic and Latvian cultures.
The name of this disease refers to the rapid movements of sufferers, which resemble a dance. In English, Sydenham’s chorea is called ‘sydenham’s chorea’ or ‘St Vitus’ dance’.
Sydenham’s chorea is most common in children (10% in cases of rheumatic fever)
Sydenham’s chorea occurs more frequently in females than in males.
The overall incidence of acute rheumatic fever and rheumatic heart disease is not declining.
Recent data quote the incidence of acute rheumatic fever as 0.6-0.7/1,000 population in the US and Japan compared to 15-21/1,000 population in Asia and Africa.
The prevalence of acute rheumatic fever and Sydenham’s chorea has progressively decreased in developed countries in recent decades.
Age of onset
Most cases occur under the age of 18 years.
Onset in adulthood is relatively rare and most cases are associated with an exacerbation of the condition after having already experienced it in childhood.
Sydenham’s chorea is caused by an autoimmune response following infection with group A β-haemolytic streptococci (Streptococcus pyogenes)
Two cross-reactive streptococcal antigens, M-protein and N-acetyl-beta-D-glucosamine, have been identified, whereby infection leads to the production of autoantibodies against host tissues (molecular mimicry) causing a variety of streptococcal-related diseases including Sydenham’s chorea but also rheumatic heart disease and nephritic syndrome.
Autoantibodies against basal ganglia proteins have been found in Sydenham’s chorea, but they are not specific.
Dopamine receptor autoantibodies have been reported to correlate with clinical symptoms.
Whether these antibodies represent an epi-phenomenon or are pathogenic remains to be demonstrated.
Symptoms and signs
Sydenham’s chorea is characterised by the abrupt onset (sometimes within hours) of neurological symptoms and signs, classically chorea.
Usually all four limbs are affected in chorea, but there are reported cases where only one side of the body is affected (hemichorea).
Typical chorea includes:
- repeated hyperextension of the wrist,
- grimacing,
- lip pouting.
The fingers may move as if playing the piano.
There may be tongue fasciculations (‘bag of worms’) and an inability to support the tongue protrusion or closing of the eyes.
There is usually a loss of fine motor control, particularly evident in handwriting if the child is of school age.
Speech is often affected (dysarthria), as is walking; the legs will suddenly give way or move off to one side, giving an irregular gait and the impression of jumping or dancing.
Underlying the abnormal movements is often a low tone (hypotonia) that may not become apparent until treatment to suppress chorea begins.
In more severe cases, loss of tone and weakness predominate (chorea paralyticum).
The severity of the condition can vary greatly, from simple unsteadiness in walking and difficulty with handwriting, to the extreme of being completely unable to walk, talk or feed oneself.
Movements cease during sleep. The eye muscles are not affected.
Neurological symptoms and signs include:
- behavioural change,
- dysarthria,
- loss of fine and gross motor control resulting in deterioration of handwriting,
- headaches,
- slowed cognition,
- facial grimacing,
- nervousness,
- tremor,
- muscle hypotonia,
- fasciculations,
- milking sign (a spasm of the hand with rhythmic increase and decrease of tension, as in hand milking).
Non-neurological manifestations of acute rheumatic fever may be present, in particular carditis (up to 70% of cases, often subclinical, so echocardiography is required), arthritis, erythema marginata, subcutaneous nodules, rash.
Sydenham’s chorea, being a neuropsychiatric disorder, in addition to motor problems also includes:
- emotional lability (mood swings or inappropriate mood),
- anxiety,
- attention deficit.
These symptoms may precede the motor symptoms and signs or occur simultaneously with them.
Diagnosis
Sydenham’s chorea is doubted during anamnesis and objective examination.
The diagnosis is then made by the typical acute onset in the weeks following a sore throat or other minor infection, in addition to evidence of inflammation (increased CRP and/or ESR) and evidence of a recent streptococcal infection.
To confirm a recent streptococcal infection
- sputum culture;
- anti-DNAsi B titre (peaks at 8-12 weeks post-infection);
- anti-streptolysin O titre (peaks at 3-5 weeks).
None of these tests is 100% reliable, particularly when the infection occurred several months earlier.
Further tests are directed more towards alternative diagnoses and other manifestations of rheumatic fever:
- echocardiography;
- electroencephalography;
- lumbar puncture;
- magnetic resonance imaging or computed tomography scan of the brain (alterations of the caudate nucleus and enlargement of the putamen have been described in some patients).
There is a UFMG rating scale for Sydenham’s chorea, from the Brazilian Universidade Federal de Minas Gerais (UFMG), for research purposes, but it only examines motor function and not psychiatric/behavioural symptoms.
Differential diagnosis
Differentiating the symptoms and signs of Sydenham’s chorea from other involuntary movements such as tics and stereotypies can be difficult and as these things are not uncommon they can potentially coexist.
Diagnosis is often delayed and attributed to another condition such as nervous tics or conversion disorder.
Sydenham’s chorea must be distinguished from conditions such as:
- Tourette’s syndrome,
- systemic lupus erythematosus,
- Guillain-Barré syndrome,
- benign hereditary chorea,
- bilateral striatal necrosis,
- abetalipoproteinemia,
- ataxia-telangiectasia,
- biotin-thiamine-sensitive basal ganglia disease,
- Fahr’s disease,
- familial facial dyskinesia (Bird-Raskind syndrome),
- glutaric aciduria,
- Lesch-Nyhan syndrome,
- mitochondrial disorders,
- Huntington’s disease,
- Wilson’s disease,
- hyperthyroidism,
- pregnancy (chorea gravidarum),
- drug intoxication,
- side effects of certain anticonvulsants (e.g. phenytoin)
- psychotropic agents.
PANDAS syndrome (paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) is similar, but is not characterised by Sydenham’s motor dysfunction.
PANDAS presents with tics and a psychological component and occurs much earlier, days to weeks after infection rather than 6-9 months later.
The therapeutic management of Sydenham’s chorea is based on the following principles:
- Eliminate the streptococcus with antibiotics: it may be of no use for the index patient, but further spread of that specific clone will be prevented.
- Treat the movement disorder.
- Immunosuppression (prednisolone generally reduces the average duration of symptoms from 9 weeks to 4 weeks).
- Prevention of relapse and further cardiac damage.
- Managing disability.
- Occupational therapy and physiotherapy are helpful in maintaining muscle function and tone.
- Treatment with sodium valproate is effective in controlling symptoms, but does not accelerate recovery.
- Haloperidol has been used previously, but has caused serious side effects, e.g. tardive dyskinesia.
- There are clinical cases supporting carbamazepine and levetiracetam; other tried drugs include pimozide, clonidine and phenobarbitone.
- A course of penicillin is usually administered at diagnosis to permanently eliminate any remaining streptococci.
- Penicillin prophylaxis, on the other hand, is essential to treat the cardiac features of rheumatic fever, even if subclinical (American Heart Association guidelines).
If the case is isolated chorea, it is debatable whether the cardiac risk justifies prophylaxis or not, however it is likely to reduce recurrences.
Prognosis
50% of patients with acute Sydenham’s chorea recover spontaneously after 2-6 months, whereas mild or moderate chorea or other motor symptoms may persist, in some cases, for more than two years.
Ten per cent of patients reported long-term tremor in one study (10-year follow-up).
Long-term neuropsychiatric difficulties are increasingly recognised (49 studies so far, in particular obsessive-compulsive disorder but also attention deficit hyperactivity disorder, affective disorders, tic disorders, executive function disorders, psychotic features and language disorders).
Relapses and relapses are possible, especially during pregnancy.
Relapses
Relapses are observed in 16-40% of cases.
Relapse is more likely with poor compliance with penicillin prophylaxis.
Intramuscular penicillin is administered every 2-3 weeks compared to the 4-week regimen and oral penicillin is also prescribed.
Relapses are sometimes associated with increased ASO titre or other evidence of new streptococcal infection.
There is no obvious clinical parameter that can predict those at risk of relapse.
More likely if non-remission in the first six months, it may recur with pregnancy (chorea gravidorum).
Higher relapse rates observed at longer follow-up: may recur up to 10 years after the initial episode, thus may be underestimated by series with shorter follow-up.
Recurrence is usually characterised only by chorea, although the original case was associated with rheumatic fever.
In some cases carditis, after an initial improvement, recurred again.
Some authors suggest that recurrent chorea is a completely different disease from Sydenham’s chorea.
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