What is the diagnosis and recommended management for a child or adolescent presenting with acute involuntary rapid jerky movements of the limbs, face or trunk, accompanied by emotional lability, irritability, and muscle weakness?

Sydenham's Chorea

Diagnosis

Sydenham's chorea is diagnosed clinically in a child or adolescent presenting with acute-onset involuntary rapid jerky movements (chorea) of the limbs, face, or trunk, accompanied by emotional lability, irritability, and muscle weakness, particularly when there is a history of recent streptococcal infection or acute rheumatic fever. 1

Key Clinical Features to Identify

• Movement characteristics: Irregular, rapid, non-stereotyped movements that flow randomly from one body part to another, creating a "dance-like" appearance during gait 1
• Associated features: Muscle weakness (hypotonia), emotional lability, irritability, and behavioral changes are characteristic 1
• Temporal pattern: Movements are involuntary, worsen with stress or voluntary activity, disappear during sleep, and have a monophasic course 2
• Age and context: Typically affects children aged 5-15 years, with female predominance; occurs 1-8 months after group A streptococcal pharyngitis 1

Differentiation from Other Movement Disorders

Distinguish from tics: Tics are suppressible, associated with premonitory urges, have childhood onset with rostrocaudal progression, and may respond to dopamine antagonists—whereas chorea lacks suppressibility and premonitory sensations 3

Distinguish from myoclonus: Myoclonus consists of brief shock-like jerks (typically <100ms duration) that are more stereotyped and consistent, whereas chorea involves flowing, random movements of longer duration 2, 4

Distinguish from functional movement disorders: Functional jerks show variable and inconsistent phenomenology, are distractible and entrainable, may have acute onset after physical trauma, and demonstrate a Bereitschaftspotential (pre-movement potential) on neurophysiology 3

Distinguish from drug-induced movements: Acute dystonia from antipsychotics presents with sustained muscle contractions and spastic posturing rather than flowing choreiform movements, occurs within hours to weeks of medication initiation, and responds rapidly to anticholinergics 5

Diagnostic Workup

• Brain MRI without contrast is the optimal imaging modality to exclude structural causes such as stroke, demyelinating disease, or basal ganglia lesions 1
• Laboratory evaluation: Anti-streptolysin O (ASO) titers, anti-DNase B, throat culture to confirm recent streptococcal infection; complete blood count, metabolic panel to exclude other causes 1
• Exclude metabolic causes: Hyperthyroidism, hypoparathyroidism, hypoglycemia, and kernicterus should be ruled out 6
• Cardiac evaluation: Echocardiogram to assess for rheumatic heart disease, as Sydenham's chorea is a major Jones criterion for acute rheumatic fever 1

Management

Treat the underlying streptococcal infection and provide secondary prophylaxis with penicillin to prevent recurrent rheumatic fever, while managing chorea symptomatically if movements cause functional impairment. 1

Primary Treatment Approach

• Antibiotic therapy: Administer appropriate antibiotics to eradicate streptococcal infection (penicillin or erythromycin if penicillin-allergic) 1
• Secondary prophylaxis: Long-term penicillin prophylaxis (benzathine penicillin G 1.2 million units IM every 3-4 weeks, or oral penicillin V 250mg twice daily) to prevent recurrent streptococcal infections and rheumatic fever 1
• Duration of prophylaxis: Continue until at least age 21 years or for 5 years after the last episode, whichever is longer; lifelong if carditis is present 1

Symptomatic Management of Chorea

If chorea causes significant functional impairment or distress, consider dopamine-depleting agents or dopamine antagonists, with careful monitoring for adverse effects. 1

• First-line symptomatic agents: Valproic acid (15-20 mg/kg/day) or carbamazepine (10-20 mg/kg/day) are preferred due to better tolerability 1
• Alternative agents: Haloperidol (0.5-2 mg twice daily) or risperidone (0.5-2 mg twice daily) may be used for severe cases, but require close monitoring 1

Critical Monitoring for Antipsychotic Use

If antipsychotics are prescribed, monitor vigilantly for acute dystonia, akathisia, drug-induced parkinsonism, and tardive dyskinesia. 7

• Acute dystonia risk: Young age is the most significant risk factor; children and adolescents are at higher risk than adults, with males more susceptible 5
• Acute dystonia treatment: Administer benztropine 1-2 mg IV/IM immediately if acute dystonia occurs, providing rapid relief within minutes 5
• Prophylaxis consideration: Consider prophylactic anticholinergic agents (benztropine 0.5-1 mg twice daily) in high-risk patients, particularly young males on high-potency agents 5
• Drug-induced parkinsonism: Can develop within hours to weeks of starting antipsychotics; presents with rigidity, bradykinesia, and tremor 7

Common Pitfalls to Avoid

• Do not miss cardiac involvement: Always perform echocardiography, as rheumatic heart disease may be asymptomatic but requires more aggressive prophylaxis 1
• Do not confuse with tics: The absence of suppressibility and premonitory urges distinguishes chorea from tic disorders 3
• Do not overlook functional impairment: Even if movements appear mild, assess impact on activities of daily living, school performance, and emotional well-being 1
• Avoid premature discontinuation of prophylaxis: Recurrence risk remains high without adequate duration of antibiotic prophylaxis 1

Prognosis and Follow-up

• Natural history: Sydenham's chorea is typically self-limited, with spontaneous resolution over 3-6 months in most cases, though some patients may have symptoms lasting up to 2 years 1
• Recurrence: Occurs in 2-5% of patients, particularly with subsequent streptococcal infections if prophylaxis is inadequate 6, 1
• Long-term monitoring: Periodic cardiac evaluation to detect development of rheumatic heart disease, even years after the initial episode 1