Objective: To review the pathophysiology of neuroimmune disease caused by streptococcal infection using as an example a case of a 59-year-old man with choreiform movements and psychosis having elevated anti-streptolysin O (ASO) titer.

Background: Excessive activation of immune cells after a group A β-hemolytic streptococcal infection can lead to antibodies attacking the basal ganglia, disrupting movement, cognition, and behavior. This can result in syndromes such as Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection (PANDAS) and Sydenham chorea.

Method: Case report and review of literature

Results: 59-year-old man with a history of recurrent pharyngitis during childhood, presented with abnormal movements manifesting as brief elevation of the right shoulder, orofacial dyskinesias, followed by dystonic rightward head turn, and non-rhythmic choreiform shoulder shrugging and abduction movements associated with insomnia and visual hallucinations for 7 days. Due to the concern for status epilepticus, he was intubated and sedated with propofol, with continuous electroencephalogram capturing involuntary movements without epileptiform correlation. He was given a 5-day course of intravenous immunoglobulins for possible autoimmune encephalitis (steroids were avoided since infectious etiology could not be ruled out), without any clinical response, with re-emerging choreiform movements off sedation. Diagnostic workup showed the following: elevated serum ASO titer at 297 (normal <200) and anti-DNAase antibody titer at 148 (normal <85), mild elevation of ESR and CRP and normal brain imaging. Mayo Autoimmune encephalitis panel was negative. As a phenomenology similar to PANDAS was suspected, the patient was treated with a 7-day course of Ceftriaxone, methylprednisolone 1000 mg daily, and risperidone 1 mg every 12 hours for 5 days leading to complete resolution of the abnormal movements and normalization of mental status. He was discharged home with 6 weeks of prednisone taper.

Conclusion: The autoantibodies generated due to the cross-reactivity of the group A carbohydrate of the streptococci impairs the activation of the calcium-calmodulin-dependent protein kinase II (CaM kinase II) in the basal ganglia cells. The understanding of the pathophysiology of Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection can aid to an early diagnosis and treatment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/adult-onset-chorea-and-psychosis-in-a-59-year-old-man-with-elevated-anti-streptolysin-o-aso-titer/