What is Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS), including its presentation, diagnostic criteria, and management?

PANDAS: A Controversial and Unproven Hypothesis

PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections) should be considered only as a yet-unproven hypothesis, not an established diagnosis, and routine laboratory testing for GAS, long-term antistreptococcal prophylaxis, or immunoregulatory therapy (IVIG, plasma exchange) are NOT recommended for this disorder 1.

What PANDAS Purports to Be

PANDAS was proposed in 1998 as a hypothesis that childhood obsessive-compulsive disorder (OCD) and/or tics may arise from a post-streptococcal autoimmune process 1. The proposed mechanism suggests that Group A Streptococcus (GAS) infection triggers autoimmune responses that cross-react with brain tissue (particularly basal ganglia), similar to the pathophysiology of Sydenham chorea in acute rheumatic fever 2.

Proposed Diagnostic Criteria

The original criteria include 3, 4:

• Pediatric onset (prepubertal)
• Presence of OCD and/or tic disorder
• Abrupt onset and/or episodic course of symptoms
• Temporal association with GAS infection
• Associated neurological abnormalities (motor hyperactivity, choreiform movements, or tics)

Critical Distinction: PANDAS vs. Sydenham Chorea

PANDAS must be differentiated from Sydenham chorea, which is an established major manifestation of acute rheumatic fever 5. Key differences:

• Sydenham chorea presents with actual chorea (involuntary, irregular, flowing movements) and hypotonia, not tics 5
• PANDAS presents with tics and OCD symptoms, not true chorea 5
• Sydenham chorea has established diagnostic criteria and treatment protocols 5
• PANDAS remains a hypothesis without validated biomarkers 1

The Evidence Problem

Why PANDAS Remains Unproven

The American Heart Association's 2009 scientific statement explicitly states that PANDAS should be considered only as a yet-unproven hypothesis 1. This remains the most authoritative guideline position. Here's why:

1. No validated biomarkers exist 6:

   • ASO and anti-DNase B titers merely indicate prior streptococcal exposure, not causation
   • Anti-basal ganglia antibodies lack diagnostic accuracy
   • The Cunningham Panel has not demonstrated adequate individual-level diagnostic accuracy
   • No currently available test can definitively diagnose PANDAS

2. Prospective studies have failed to demonstrate consistent temporal associations 7, 6:

   • Blinded prospective studies have not shown a reliable population-level association between GAS infections and tic/OCD exacerbations
   • The high background prevalence of both GAS exposure and primary neurodevelopmental disorders in children creates conditions for incidental temporal co-occurrence

3. Primary tic disorders have strong genetic heritability 6:

   • Heritability estimates of 50-80%
   • First-degree familial risk ratios approximately 18-fold
   • This suggests most tic disorders have primary neurodevelopmental origins, not autoimmune

4. Research has shifted away from PANDAS 2:

   • The field has moved toward the broader concept of Pediatric Acute-Onset Neuropsychiatric Syndrome (PANS)
   • PANS recognizes sudden-onset OCD symptoms can occur in response to various infections and insults, not just streptococcus
   • This shift reflects the lack of specificity for streptococcal causation

Clinical Presentation (When Suspected)

When PANDAS is suspected, reported symptoms include 8, 9, 3:

• Sudden, dramatic onset of severe OCD behaviors (hand washing, contamination fears)
• Tics (motor or vocal)
• Daytime urinary urgency and frequency without dysuria or fever (notably common in one prospective series—58% of patients) 3
• Behavioral regression
• Emotional lability, anxiety, irritability
• Sleep disturbances
• Deterioration in handwriting or school performance

Critical caveat: These symptoms overlap extensively with primary OCD, tic disorders, and other psychiatric conditions 10, 6.

Diagnostic Approach: Exclusion is Key

PANDAS and PANS are diagnoses of exclusion 7, 6. The diagnostic workup must prioritize ruling out:

High-Priority Differential Diagnoses 5, 11:

1. Sydenham chorea (if movement disorder present)

   • Look for true chorea (flowing, irregular movements), not tics
   • Check for hypotonia
   • Evaluate for rheumatic fever criteria
   • Echocardiogram for carditis

2. Autoimmune encephalitis

   • NMDAR, LGI1, or other antibody-mediated encephalitis
   • CSF analysis with cell count, protein, oligoclonal bands
   • Brain MRI with contrast
   • Serum and CSF autoantibody panels

3. Primary psychiatric disorders 10:

   • Major depressive disorder
   • Generalized anxiety disorder
   • Primary OCD (most common)
   • Primary tic disorder/Tourette syndrome
   • Important: In one tertiary referral center study, 8 of 21 patients referred with pre-diagnosis of PANDAS had major psychiatric disorders, and NONE fulfilled PANDAS criteria (p<0.01) 10

4. Other neurological conditions:

   • Wilson disease
   • Huntington disease
   • Moyamoya syndrome (MRI/MRA)
   • Metabolic disorders
   • Monogenic dyskinesia syndromes

5. Infectious causes:

   • HSV encephalitis
   • Mycoplasma pneumoniae
   • Lyme disease (in endemic areas)
   • Other viral encephalitides

Workup Strategy

In high acute rheumatic fever (ARF) incidence regions 5:

• Sydenham chorea is the most likely etiology unless proven otherwise
• Extensive laboratory testing and neuroimaging may not be required if clinical presentation is typical
• Throat culture and streptococcal serology
• Echocardiogram
• Consider limited additional testing

In low ARF incidence regions 5:

• More extensive differential diagnosis is essential
• Brain MRI with MR angiography (rule out vascular pathology, structural lesions)
• Autoimmune and metabolic studies
• Genetic evaluation for monogenic dyskinesia disorders
• CSF analysis if encephalitis suspected
• Comprehensive psychiatric evaluation

Management: Evidence-Based Caution

What NOT to Do (Class III Recommendation)

The American Heart Association explicitly recommends AGAINST 1:

• Routine laboratory testing for GAS to diagnose PANDAS
• Long-term antistreptococcal prophylaxis to prevent PANDAS
• Immunoregulatory therapy (IVIG, plasma exchange) to treat PANDAS exacerbations

Rationale: Until carefully designed, well-controlled studies establish a causal relationship between PANDAS and GAS infections, these interventions carry significant risks without proven benefit 1.

Risks of Overdiagnosis 6

Diagnostic imprecision carries direct clinical consequences:

• Children may be exposed to treatments with significant risk profiles (IVIG complications, plasma exchange risks, antibiotic resistance from prolonged prophylaxis)
• Evidence-based therapies for primary psychiatric disorders are delayed
• Families may pursue unproven treatments at significant financial and emotional cost

If GAS Infection is Documented

For acute GAS pharyngitis with concurrent neuropsychiatric symptoms 3:

• Treat the streptococcal infection appropriately with standard antibiotics (penicillin or amoxicillin)
• One small prospective study suggested OCD symptoms resolved with appropriate antibiotic treatment of the sentinel GAS episode 3
• However, this finding requires replication in larger, controlled studies

Evidence-Based Treatment Approach

Treat the psychiatric symptoms with standard, evidence-based therapies:

1. For OCD symptoms:

   • Cognitive-behavioral therapy (CBT) with exposure and response prevention
   • SSRIs (fluoxetine, sertraline, fluvoxamine)
   • Combination therapy for moderate-to-severe cases

2. For tic disorders:

   • Comprehensive Behavioral Intervention for Tics (CBIT)
   • Alpha-2 agonists (guanfacine, clonidine) for moderate tics
   • Antipsychotics (aripiprazole, risperidone) for severe, impairing tics

3. Multidisciplinary care 10:

   • Psychiatry or child psychiatry
   • Neurology (if movement disorder present)
   • Infectious disease (if recurrent infections)
   • Psychology for behavioral interventions

Monitoring

If PANDAS diagnosis is entertained 10:

• Use objective rating scales to monitor symptoms (CY-BOCS for OCD, YGTSS for tics)
• Document temporal relationship between infections and symptom changes
• Most patients referred with pre-diagnosis of PANDAS do not have objective criteria for symptom monitoring 10

Emerging Research (Not Ready for Clinical Use)

Recent molecular research has identified potential biomarkers 12, 7, 6:

• Anti-D1R autoantibodies: Candidate biomarkers for PANDAS/PANS neuropsychiatric phenotypes
• Anti-D2R autoantibodies: Associated with Sydenham chorea movement phenotypes
• These require independent replication in unselected populations before clinical application

One case report identified Argonaute family protein autoantibodies (AGO-IgG) in a patient diagnosed with PANDAS, with titers decreasing after IVIG coinciding with symptomatic improvement 12. However, this represents a single case and does not validate PANDAS as a distinct entity.

Common Pitfalls to Avoid

1. Assuming elevated streptococcal titers prove causation: High ASO or anti-DNase B titers only indicate prior exposure, which is extremely common in children 6

2. Missing primary psychiatric disorders: The majority of children referred with suspected PANDAS have primary OCD or tic disorders 10

3. Delaying evidence-based psychiatric treatment: While pursuing the PANDAS hypothesis, children miss critical windows for effective CBT and pharmacotherapy

4. Overlooking Sydenham chorea: If true chorea is present, this is an established diagnosis requiring specific management including secondary antibiotic prophylaxis 5

5. Pursuing unvalidated immunotherapy: IVIG and plasma exchange carry significant risks and lack proven efficacy for PANDAS 1

Bottom Line

PANDAS remains a hypothesis, not an established diagnosis 1. The concept has stimulated research but lacks the evidence base to support specific diagnostic testing or immunomodulatory treatments. Clinicians should focus on rigorous differential diagnosis, evidence-based treatment of psychiatric symptoms, and appropriate management of documented infections 7, 6. The high background rates of both streptococcal exposure and primary neurodevelopmental disorders in children mean temporal associations are often coincidental rather than causal 6.