Delayed recognition of Sydenham chorea in a child referred for suspected attention-deficit/hyperactivity disorder: a pediatric case report

Background Attention problems, emotional lability, and behavioral dysregulation may precede or accompany Sydenham chorea (SC). When choreiform movements are subtle, these symptoms may suggest attention-deficit/hyperactivity disorder (ADHD), delaying recognition of an acquired movement disorder. Case presentation A 7-year-old girl with previously unremarkable development was referred for poor concentration, poor posture, irritability, and hyperactivity/impulsivity. Symptoms evolved gradually from age 4. Bilateral fine irregular choreiform movements, spilling water, handwriting deterioration, and gait instability were evident by ages 5–6. She had recurrent group A streptococcal infections and a family history of rheumatic fever. Examination showed bilateral action-enhanced chorea, hypotonia, irregular finger-to-nose performance with superimposed involuntary movements, impaired rapid alternating hand movements, and unstable tandem gait. She had no tics, obsessive-compulsive symptoms, restrictive eating, or clinically significant anxiety. Streptococcal antibody titers were elevated. Brain MRI and investigations for metabolic, autoimmune, antiphospholipid, demyelinating, and thyroid disorders were unrevealing. SC was diagnosed. Chorea, handwriting, spilling, irritability, posture, and gait improved following prednisolone, short-term risperidone, and oral penicillin prophylaxis. She remained relapse-free through age 18 and entered university. Exploratory testing showed cerebrospinal fluid peptide enzyme-linked immunosorbent assay reactivity and serum-only N -methyl- d -aspartate receptor (NMDAR) antibody positivity by live cell-based assay; neither finding was considered diagnostic of anti-NMDAR encephalitis. Discussion/conclusion Changes from premorbid functioning, handwriting deterioration, spilling, postural or gait abnormalities, and irregular distal movements may indicate an acquired movement disorder in children referred for suspected ADHD. An elevated rating-scale score alone does not establish ADHD. Exploratory neuronal antibody findings require cautious interpretation without a compatible clinical syndrome.