Adult-Onset Sydenham Chorea Mimicking a Functional Movement Disorder: A Case Report
Dalibor Mihajlovic1*, Yazeed Bani Hamad2, Christoph Baumsteiger1, Zaid Bani Hamad1
1Department of Neurology, Katholisches Karl-Leisner Klinikum gGmbH, Kleve, Germany.
2Department of Psychiatry and Psychotherapy, LVR-Klinik Bedburg-Hau, Bedburg-Hau, Germany.
*Corresponding Author: Dalibor Mihajlovic, MD, Department of Neurology, Katholisches Karl-Leisner Klinikum gGmbH, Kleve, Germany.
DOI: https://doi.org/10.58624/SVOANE.2026.07.024
Received: July 10, 2026
Published: August 04, 2026
Citation: Mihajlovic D, Bani Hamad Y, Baumsteiger C, Bani Hamad Z. Adult-Onset Sydenham Chorea Mimicking a Functional Movement Disorder: A Case Report. SVOA Neurology 2026, 7:4, 163-169. doi.org/10.58624/SVOANE.2026.07.024
Abstract
Background: Sydenham chorea is a post-streptococcal autoimmune movement disorder and one of the major manifestations of acute rheumatic fever. Adult-onset disease is rare and may be diagnostically challenging because positive streptococcal serology is supportive but not disease-specific.
Case Presentation: We report a 38-year-old man with progressive predominantly unilateral choreiform movements of the right shoulder and proximal arm with intermittent facial involvement. MRI and EEG were repeatedly normal. CSF showed no pleocytosis or intrathecal immunoglobulin synthesis. Wilson disease, Huntington disease, autoimmune encephalitis, vascular chorea, infectious, metabolic, drug-induced and paraneoplastic causes were considered and became unlikely after extensive evaluation. Persistently elevated anti-DNase B titres and elevated ASO titres supported antecedent Group A streptococcal exposure. Mild Jack-in-the-box tongue was present, while Milkmaid’s grip was absent. Partial distractibility initially raised concern for functional movement disorder.
Conclusion: Adult-onset Sydenham chorea should neither be diagnosed solely because ASO or anti-DNase B titres are elevated nor dismissed because the patient is an adult or shows partial distractibility. Diagnosis requires synthesis of movement phenomenology, supportive streptococcal serology and systematic exclusion of competing disorders.
Keywords: Sydenham chorea; adult-onset chorea; autoimmune chorea; Group A streptococcus; functional movement disorder; anti-DNase B; ASO
