PANDAS describes a group of acute-onset neuropsychiatric disorders in children triggered by an autoimmune response to Group A β-haemolytic streptococcal (GAS) infection.
Proposed mechanism: antibodies generated against streptococcal antigens cross-react with basal ganglia neurons (molecular mimicry), leading to abrupt psychiatric and neurological symptoms.
First described in the late 1990s, PANDAS remains controversial and is considered a subtype of Paediatric Acute-onset Neuropsychiatric Syndrome (PANS).

⚠️ Key Clinical Features

Obsessive–Compulsive Disorder (OCD): Rapid, dramatic onset of intrusive thoughts, compulsions, rituals.
Tics: Motor or vocal tics resembling Tourette’s syndrome; often emerge suddenly after infection.
Other Neuropsychiatric Symptoms: Emotional lability, anxiety, separation anxiety, irritability, behavioural regression.
Somatic symptoms: Sleep disturbances, enuresis, handwriting deterioration, and in some cases food restriction or anorexia-like symptoms.

🧪 Diagnosis

Diagnosis is clinical, supported by history of a recent streptococcal infection.
Proposed criteria:
- Presence of OCD and/or tic disorder.
- Prepubertal onset (usually 3–12 years).
- Abrupt onset with episodic course.
- Temporal association with streptococcal infection.
- Neurological abnormalities (e.g., hyperactivity, choreiform movements).
Investigations: ASO titres or anti-DNase B may suggest recent strep exposure, but not diagnostic.
Exclusion of other causes (e.g., Sydenham’s chorea, Tourette’s, primary OCD).

💊 Management

Eradication of Streptococcus:
- First-line: Antibiotics (penicillin V, amoxicillin, or azithromycin if penicillin-allergic).
- Long-term prophylaxis sometimes considered in recurrent cases (though evidence mixed).
Neuropsychiatric Symptom Management:
- CBT and SSRIs for OCD (standard of care, as in non-PANDAS OCD).
- Risperidone or other atypical antipsychotics for disabling tics/behavioural symptoms (specialist-led).
Immunomodulation (specialist use only):
- IVIG or plasmapheresis may benefit severe, refractory cases, but evidence remains limited and controversial.
Supportive care: Multidisciplinary approach – child psychiatry, paediatrics, psychology, education support.

📈 Prognosis

Symptoms often improve with antibiotics and psychiatric support, but relapses are common with new infections.
Some children progress to chronic OCD or tic disorders despite treatment.
Early recognition is essential to reduce long-term psychological and functional impact.

📌 Key Exam Pearls

PANDAS is a clinical diagnosis – no specific lab test confirms it.
Always rule out Sydenham’s chorea in post-strep neuropsychiatric presentations (part of rheumatic fever spectrum).
Antibiotics may improve psychiatric symptoms → unique compared to primary OCD/Tourette’s.
Still controversial – some guidelines (esp. in UK) prefer term PANS for broader differential.

🔗 References

Elia J. et al, Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections, J Child Neurol.
Oxford Handbook of Clinical Medicine, p.692 – Tic Disorders.
Royal College of Psychiatrists: Guidance on PANS/PANDAS (2020).

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Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections

🧠 Introduction