What is the provisional diagnosis, supporting physical signs, and management for a previously well child or adolescent presenting with abnormal, jerky, dancing-like movements, suggestive of Sydenham's chorea?

Sydenham's Chorea: Diagnosis and Management

A. Provisional Diagnosis

The provisional diagnosis is Sydenham's chorea, the most common cause of acute-onset chorea in childhood and a neurological manifestation of acute rheumatic fever following Group A streptococcal infection. 1, 2

B. Four Physical Signs to Support the Diagnosis

1. Choreiform Movements with Suppressibility

• Involuntary, jerky, purposeless, non-stereotyped, "dance-like" movements affecting the face, trunk, or extremities that flow randomly from one body part to another 1, 3
• The ability to temporarily suppress these movements through conscious effort is a crucial diagnostic feature that distinguishes Sydenham's chorea from other movement disorders 4
• Movements may be unilateral in 30% of cases 1

2. Muscle Hypotonia and Weakness

• Decreased muscle tone frequently accompanies the choreiform movements 3, 5
• Patients demonstrate difficulty with motor tasks such as grasping utensils or maintaining posture 2, 5

3. Emotional Lability and Neuropsychiatric Features

• Emotional instability, mood changes, obsessive-compulsive symptoms, attention deficit, and behavioral changes are characteristic 3, 5
• These neuropsychiatric features may precede or accompany the motor symptoms 5

4. Cardiac Findings (Carditis)

• Systolic heart murmur indicating valvular involvement, most commonly mitral or aortic regurgitation 2, 6
• Cardiac manifestations are present in most patients as part of acute rheumatic fever 5

C. Outline of Management

Diagnostic Workup

Laboratory Investigations:

• Elevated anti-streptolysin O (ASO) titer, anti-DNAse B antibodies, or positive streptozyme to document recent streptococcal infection 1, 2
• Serum ceruloplasmin to exclude Wilson's disease 1
• Antiphospholipid antibodies and lupus serology if systemic lupus erythematosus is suspected 3, 7
• Inflammatory markers (ESR, CRP) are typically elevated 6

Cardiac Evaluation:

• Echocardiogram to assess for valvular involvement and carditis 2, 6
• ECG to evaluate for prolonged PR interval 6

Neuroimaging:

• Brain MRI without contrast is the optimal imaging modality, though it may be normal in early stages 1, 4

Treatment Approach

1. Antibiotic Therapy (Primary Treatment):

• Initiate penicillin for acute treatment and long-term prophylaxis to prevent recurrent streptococcal infections and minimize cardiac damage 2, 5
• Prophylactic antibiotics are essential to prevent future episodes of acute rheumatic fever 2

2. Symptomatic Treatment of Chorea:

• Valproic acid is a first-line antichoreic agent 5
• Dopamine antagonists (neuroleptics such as haloperidol) are effective for symptomatic control 3, 6
• Treatment is indicated when movements are debilitating, though symptoms often resolve spontaneously within months 5, 8

3. Cardiac Management:

• ACE inhibitors (captopril) and diuretics (furosemide) for cardiac insufficiency if present 6
• Antiplatelet or anticoagulation therapy if antiphospholipid antibodies are positive 3

4. Immunomodulatory Therapy (If Severe):

• Glucocorticoids alone or combined with immunosuppressive agents may be considered for severe cases or when associated with systemic lupus erythematosus 3

5. Supportive Care:

• Speech therapy and occupational therapy for functional improvement 1
• Management of neuropsychiatric symptoms including obsessive-compulsive features 5

Important Clinical Pitfalls

• Do not misdiagnose as a "fidgety" child, psychiatric manifestation, or psychotic agitation 2
• Always exclude systemic lupus erythematosus in the differential diagnosis, particularly if there are accompanying joint complaints, growth retardation, or cytopenias 7
• Remember that neuropsychiatric symptoms may precede motor symptoms and can be persistent even after chorea resolves 5
• A significant proportion of patients may have persistent chorea despite treatment, requiring long-term follow-up 5