# PANDAS/PANS: Autoimmune Neuropsychiatric Disorders

## Overview

PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections) was proposed by Swedo and colleagues in 1998 as a distinct clinical entity in which Group A Streptococcal (GAS) infection triggers acute-onset OCD and/or tic disorders in prepubertal children. PANS (Pediatric Acute-onset Neuropsychiatric Syndrome) is a broader, etiologically agnostic term encompassing abrupt-onset OCD or eating restriction with concurrent neuropsychiatric symptoms, regardless of identified infectious trigger. The core controversy is whether post-infectious autoimmunity represents a validated, distinct etiology for OCD and tics in children, or whether the evidence remains insufficient to justify immunomodulatory treatments. The field is sharply divided: proponents view PANDAS/PANS as an underdiagnosed condition requiring immunological treatment, while skeptics argue the evidence base is weak and the treatments carry significant risks. Regardless of where one falls in this debate, standard psychiatric treatment with ERP and SSRIs remains appropriate and should not be delayed.

## PANDAS: Proposed Diagnostic Criteria (Swedo et al., 1998)

The proposed PANDAS criteria require all five of the following: the presence of OCD and/or a tic disorder, prepubertal onset (typically ages 3-12), abrupt onset of symptoms or a dramatic episodic course with a relapsing-remitting pattern, temporal association between symptom onset or exacerbation and GAS infection, and neurological abnormalities during exacerbations such as choreiform movements or motoric hyperactivity.

### PANDAS vs. PANS Criteria Comparison

| Feature | PANDAS | PANS |
|---------|--------|------|
| Trigger | GAS infection specifically required | Any infectious or non-infectious trigger (etiology agnostic) |
| Core symptoms | OCD and/or tic disorder | Abrupt-onset OCD or severely restricted food intake |
| Age requirement | Prepubertal (ages 3-12) | Not specified |
| Temporal association | Required with GAS infection | Not required with specific trigger |
| Course | Relapsing-remitting linked to GAS | Abrupt, dramatic onset |
| Neurological signs | Required (choreiform movements, motoric hyperactivity) | Not required |
| Additional neuropsychiatric symptoms | Not specified in criteria | Required from ≥2 categories |

## PANS: Proposed Diagnostic Criteria (Swedo et al., 2012)

PANS criteria require an abrupt, dramatic onset of OCD or severely restricted food intake, concurrent with additional neuropsychiatric symptoms from at least two of the following categories: anxiety (especially separation anxiety), emotional lability and/or depression, irritability, aggression, and/or oppositional behaviors, behavioral or developmental regression, deterioration in school performance, sensory or motor abnormalities, and somatic symptoms including sleep disturbance, enuresis, or urinary frequency. The symptoms must not be better explained by a known neurological or medical disorder.

## Proposed Pathophysiology

The central hypothesis is **molecular mimicry**: antibodies generated against GAS cross-react with basal ganglia neuronal tissue because of structural similarity between streptococcal M-protein and brain antigens. This mechanism is analogous to Sydenham chorea, the neuropsychiatric manifestation of post-streptococcal rheumatic fever, which causes chorea through autoimmune basal ganglia inflammation. Anti-neuronal antibodies, including anti-basal ganglia antibodies and anti-dopamine receptor antibodies, have been found in some studies, but the findings are inconsistent. The proposed mechanism involves autoimmune-mediated inflammation and dysfunction of the basal ganglia-thalamocortical circuits that are involved in OCD and tic generation. Some neuroimaging studies in PANDAS have shown basal ganglia enlargement during acute episodes, but replication has been limited.

## Evidence Supporting PANDAS/PANS

### Clinical Observations

Proponents point to the dramatic, "overnight" onset of severe OCD and/or tics in previously well children as a clinically distinct presentation that differs markedly from typical gradual-onset OCD. Case series have documented temporal clustering of symptom onset with documented GAS infections. Associated neurological signs such as chorea and motor abnormalities suggest basal ganglia involvement. The clinical similarity to Sydenham chorea, an established post-streptococcal autoimmune disorder, provides an analogical framework.

### Research Findings

Swedo et al. (1998) published the original case series of 50 children meeting PANDAS criteria. Some prospective studies have shown temporal associations between new GAS infections and OCD or tic exacerbations. Anti-neuronal antibody studies have found elevated antibodies in PANDAS versus controls in some studies, though results remain inconsistent. Case reports and small series have described improvement with immunomodulatory treatments including IVIG and plasmapheresis. The Cunningham Panel, a commercial test measuring anti-neuronal antibodies, is marketed for this population but has not been validated for clinical diagnosis.

### Treatment Studies

Perlmutter et al. (1999) conducted a small RCT with 29 participants comparing IVIG and plasmapheresis to sham in PANDAS. Both active treatments showed significant improvement at one month. This remains the most frequently cited treatment study, but it is limited by its small sample size and methodological concerns. Some studies of prophylactic penicillin suggest that reducing GAS infections may decrease neuropsychiatric exacerbations, but the evidence is mixed.

## Evidence Against / Skeptic Arguments

### Methodological Concerns

The original case series was uncontrolled and relied on retrospective parent report of symptom onset timing. GAS infections are extremely common in children, with 15-30% carrier rates, making temporal associations potentially coincidental. Many prospective studies have failed to consistently replicate the temporal association between GAS infection and symptom exacerbation. Anti-neuronal antibody findings are inconsistent across studies and may reflect non-specific immune activation rather than a specific autoimmune process. The Cunningham Panel lacks adequate sensitivity and specificity for clinical use.

### Diagnostic Validity Concerns

The PANDAS criteria are broad enough to capture many children with typical childhood-onset OCD who happen to have had a recent streptococcal infection. "Abrupt onset" is inherently subjective and may reflect recall bias or coincidental timing. The relapsing-remitting course is common in pediatric OCD regardless of infectious triggers. No validated biomarker exists to confirm autoimmune etiology in individual patients.

### Treatment Concerns

IVIG and plasmapheresis are invasive, expensive, and carry significant risks including anaphylaxis, thrombotic events, hemolysis, and infection. The only RCT was small, and its results have not been replicated in larger trials. Immunomodulatory treatments are being administered to children based on what critics consider inadequate evidence. Standard psychiatric treatments (ERP and SSRIs) are effective for OCD regardless of etiology and should not be bypassed. Antibiotic prophylaxis raises concerns about antibiotic resistance.

## Current Clinical Approach

### Assessment

A thorough psychiatric evaluation should include a detailed timeline of symptom onset and course. A throat culture or rapid strep test should be obtained if GAS infection is suspected. ASO and anti-DNase B titers can indicate recent GAS infection, though elevated titers do not confirm causation. A neurological examination should assess for choreiform movements and motor abnormalities. Neurology consultation should be considered for atypical presentations. The Cunningham Panel is not recommended as a diagnostic tool by most academic centers.

### Treatment Recommendations

**Standard psychiatric treatment should come first**: ERP and/or SRI pharmacotherapy remain the primary treatments for OCD symptoms regardless of suspected trigger. **Active GAS infection** should be treated with an appropriate antibiotic course if strep infection is confirmed. **Antibiotic prophylaxis** has insufficient evidence to recommend routinely, though it may be considered in consultation with infectious disease specialists for well-documented cases with clear temporal associations. **IVIG and plasmapheresis** should be reserved for severe, refractory cases with strong evidence of autoimmune etiology, ideally within research protocols, and should not be used as first-line treatment. **Anti-inflammatory agents** such as NSAIDs have been proposed as adjunctive treatment with limited evidence but low risk. **Corticosteroids** have some case report support but raise concerns about immunosuppression and side effects in children.

<image>A timeline diagram illustrating the proposed PANDAS model. Show a child who is psychiatrically well, then develops a GAS throat infection (with a throat culture icon), followed by an abrupt onset of severe OCD and tics within days to weeks. Show the autoimmune mechanism: streptococcal antibodies cross-reacting with basal ganglia neurons (molecular mimicry). Then show a relapsing-remitting course with exacerbations temporally linked to subsequent GAS infections. Contrast with typical pediatric OCD showing a gradual onset and chronic course.</image>

<image>A two-column comparison chart: "Evidence For PANDAS/PANS" vs. "Evidence Against / Concerns." For column: clinical similarity to Sydenham chorea, dramatic onset pattern, Perlmutter RCT showing IVIG/plasmapheresis benefit, anti-neuronal antibodies in some studies. Against column: GAS infections extremely common (coincidental association), inconsistent antibody findings, small and unreplicated treatment trials, no validated biomarker, risks of immunomodulatory treatments. Show a balance scale tipped toward uncertainty.</image>

<image>A clinical decision flowchart for evaluating suspected PANDAS/PANS. Start with abrupt-onset OCD/tics in prepubertal child. Step 1: comprehensive psychiatric evaluation and standard treatment (ERP, SSRI). Step 2: screen for GAS infection (throat culture, ASO/anti-DNase B). Step 3: neurological exam for choreiform movements. Step 4: if strong temporal association with GAS, treat infection, consider infectious disease/neurology consultation. Step 5: reserve IVIG/plasmapheresis for severe refractory cases, ideally in research settings. Emphasize that standard psychiatric treatment should not be delayed.</image>

## Clinical Pearls

Regardless of the PANDAS/PANS debate, abrupt-onset severe OCD in a child warrants urgent psychiatric evaluation and treatment with standard evidence-based approaches including ERP and SSRIs. GAS infections are extremely common in children, and temporal association does not establish causation. The Cunningham Panel is a commercial test that lacks adequate validation and should not be used for clinical diagnosis. IVIG and plasmapheresis are invasive and carry real risks; they should not be first-line treatments and are best reserved for research settings or severe refractory cases. Families often encounter PANDAS/PANS information online and may arrive with strong beliefs about the diagnosis; clinicians should acknowledge the family's concerns while providing balanced, evidence-based counseling. The most important clinical action is to not delay standard psychiatric treatment while pursuing immunological workup. Sydenham chorea is the established model of post-streptococcal autoimmune neuropsychiatric illness, and PANDAS represents the more controversial extension of this concept.

## References
- Swedo, S.E. et al. (1998). Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections: clinical description of the first 50 cases. *American Journal of Psychiatry*, 155(2), 264-271.
- Perlmutter, S.J. et al. (1999). Therapeutic plasma exchange and intravenous immunoglobulin for OCD and tic disorders in childhood. *The Lancet*, 354(9185), 1153-1158.
- Swedo, S.E. et al. (2012). From research subgroup to clinical syndrome: modifying the PANDAS criteria to describe PANS. *Pediatrics & Therapeutics*, 2(2), 113.
- Sigra, S. et al. (2018). Treatment of PANDAS and PANS: a systematic review. *Neuroscience & Biobehavioral Reviews*, 86, 51-65.
- Marazziti, D. et al. (2018). PANDAS and PANS: clinical, neuropsychological, and biological characterization of a monocentric series of patients. *Journal of Clinical Medicine*, 7(10), 333.
- Singer, H.S. et al. (2012). Moving from PANDAS to CANS. *Journal of Pediatrics*, 160(5), 725-731.