Understanding Sydenham Chorea (St. Vitus Dance)
Sydenham chorea, also known as St. Vitus dance, is the most common acquired chorea of childhood, occurring in 10-20% of children who have had acute rheumatic fever. This condition usually manifests weeks to months after an infection with group A β-hemolytic streptococci, with a peak incidence at ages 8-9 and a higher prevalence in females.
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Causes and Pathophysiology
Sydenham chorea is believed to be an autoimmune response. The group A β-hemolytic streptococci promote the production of antibodies that mistakenly attack the body’s own tissues through molecular mimicry. Specifically, antibodies against the GlcNAc epitope of streptococcal group A carbohydrate target intracellular β-tubulin and extracellular lysoganglioside GM1 in the human brain. These antibodies can also activate calcium/calmodulin-dependent protein kinase II, leading to increased dopamine release, which contributes to the neurological symptoms of Sydenham chorea.
Clinical Presentation
The hallmark symptoms of Sydenham chorea are involuntary movements (chorea), muscle weakness (hypotonia), and emotional instability. Chorea can develop abruptly or over a few days, often appearing generalized but sometimes asymmetrically affecting one side of the body (hemichorea). Parents may notice their child becoming unusually clumsy or dropping objects. The movements cease during sleep.
Hypotonia presents with signs like the pronator sign (arms and palms turn outward when held overhead) and the choreic hand (spooning of the extended hand due to wrist flexion and finger extension). Severe cases can impair the child’s ability to perform daily activities such as eating, dressing, or walking, and speech may become unintelligible. Emotional symptoms include extreme mood swings, uncontrollable crying, inattention, anxiety, obsessive-compulsive behaviors, paranoia, and reluctance to speak.
Diagnosis and Treatment
Sydenham chorea is primarily diagnosed based on clinical symptoms. Testing for antistreptolysin O titers can help confirm a recent streptococcal infection, but negative results do not rule out the diagnosis. It is essential to evaluate all patients for carditis and start long-term antibiotic prophylaxis (e.g., penicillin) to prevent rheumatic heart disease recurrence. Prophylaxis should continue until the patient is 21 years old.
For severe chorea, treatment options include valproate, carbamazepine, and dopamine receptor antagonists. The use of prednisone, intravenous immunoglobulin (IVIG), and plasma exchange has shown mixed results. Some studies suggest prednisone can reduce the time to remission, and IVIG or plasma exchange may decrease chorea severity, but these treatments do not appear to impact the long-term recurrence rate or outcomes.
Prognosis
Sydenham chorea often resolves spontaneously within a year, but recurrences can occur. Early diagnosis and management are crucial to mitigate the impact on the child’s quality of life and prevent complications associated with rheumatic heart disease.
Conclusion
Sydenham chorea is a complex condition resulting from an autoimmune reaction to a streptococcal infection. With a combination of symptom management and preventive antibiotic treatment, most children recover well, although vigilance for potential recurrences is necessary.