Relapsing paediatric acute-onset neuropsychiatric syndrome presenting with obsessive–compulsive symptoms, tic-like behaviours and psychotic-like experiences: a case report

Background

Pediatric acute-onset neuropsychiatric syndrome (PANS) is defined by the abrupt onset of obsessive–compulsive symptoms and/or severely restricted food intake, together with acute neuropsychiatric symptoms such as anxiety, emotional lability, irritability, behavioural regression, sensory or motor abnormalities, sleep disturbance and urinary symptoms [1,2]. Current clinical reports emphasize that PANS remains a clinical diagnosis requiring careful exclusion of neurological, infectious, autoimmune and primary psychiatric conditions [2,3]. Although obsessive–compulsive symptoms and anxiety are frequent, psychotic-like experiences may occur and increase diagnostic complexity [4].

Case Presentation

An 8-year-old boy presented to the child and adolescent psychiatry outpatient clinic with acute-onset neuropsychiatric symptoms that had developed within three days following an infectious episode. He reported hearing internal voices and described visual perceptual experiences with threatening and obsessional content, including statements such as, “If you do not study, your mother will die.” Intrusive sexual obsessions, marked anxiety, fearfulness, and sleep-related vulnerability were also reported.

The abrupt onset of obsessive–compulsive symptoms, together with acute anxiety, sleep disturbance, perceptual abnormalities, and a clear temporal association with infection, was considered clinically consistent with pediatric acute-onset neuropsychiatric syndrome. Neurological, infectious, autoimmune, and primary psychiatric conditions were carefully considered in the differential diagnosis, and the patient was referred for pediatric evaluation and multidisciplinary follow-up.

Treatment with fluoxetine and low-dose risperidone was initiated. Obsessive–compulsive symptoms, fearfulness, and psychotic-like experiences gradually improved during follow-up. After clinical remission and the absence of active symptoms, psychotropic medication was discontinued.

Approximately one year later, the patient experienced a symptom exacerbation following another infectious episode. The relapse was characterized by repetitive spitting, repetitive hand movements, marked fearfulness, and threatening, obsessional verbalizations such as, “If you do not study, your mother will die.” The recurrence of acute-onset obsessive–compulsive and tic-like/sensory-motor symptoms after infection further supported a relapsing course of PANS. Fluoxetine and low-dose risperidone were restarted. Partial improvement was observed with fluoxetine 20 mg, after which the dose was increased to 30 mg. At follow-up, repetitive spitting, hand movements, and evening fears had completely resolved.

Discussion

This case highlights the relapsing and diagnostically complex phenotype of PANS, in which abrupt-onset obsessive–compulsive symptoms, tic-like/repetitive behaviours, severe anxiety, sleep-related vulnerability and psychotic-like experiences may coexist. The threatening “voices” were closely linked to obsessional fear and catastrophic thinking, rather than suggesting a primary psychotic disorder. This distinction is clinically relevant, as intrusive obsessions in children may present with sensory-like qualities and complicate differential diagnosis [4].

The infection-related onset, relapse after a subsequent infectious episode, and remission with symptom-targeted treatment support a PANS formulation. The case also underscores the importance of multidisciplinary assessment, exclusion of neurological, infectious, autoimmune and primary psychiatric conditions, and longitudinal monitoring during remission and relapse [2,3,4].

Conclusions

PANS should be considered in children presenting with abrupt-onset obsessive–compulsive symptoms, tic-like behaviours, severe anxiety and psychotic-like experiences following infection. Early recognition may reduce misdiagnosis and support coordinated pediatric–psychiatric follow-up.

Keywords

PANS; pediatric acute-onset neuropsychiatric syndrome; obsessive–compulsive symptoms; tic-like behaviours; psychotic-like experiences; child psychiatry; infection-related neuropsychiatric symptoms.

References

1. Swedo SE, Leckman JF, Rose NR. From research subgroup to clinical syndrome: modifying the PANDAS criteria to describe PANS. Pediatrics & Therapeutics. 2012;2(2):113.
2. Chang K, Frankovich J, Cooperstock M, Cunningham MW, Latimer ME, Murphy TK, et al. Clinical evaluation of youth with pediatric acute-onset neuropsychiatric syndrome: recommendations from the 2013 PANS Consensus Conference. Journal of Child and Adolescent Psychopharmacology. 2015;25(1):3–13.
3. American Academy of Pediatrics Board of Directors. Pediatric acute-onset neuropsychiatric syndrome: clinical report. Pediatrics. 2025;155(3):e2024070334.
4. Hommer RE, Swedo SE. Psychotic symptoms in youth with pediatric acute-onset neuropsychiatric syndrome. Journal of Psychiatric Research. 2019;109:76–81.