Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS) is a diagnostic label applied to children who experience a sudden, dramatic onset of neuropsychiatric symptoms following a Group A Streptococcus (GAS) infection. The mechanism involves an autoimmune response where antibodies produced to fight the bacteria mistakenly attack parts of the brain, specifically the basal ganglia. Because no single laboratory test can confirm the condition, the diagnosis of PANDAS relies on a careful combination of clinical observation, patient history, and supporting laboratory evidence. The process requires a meticulous review of a child’s symptoms and their timing in relation to a preceding infection.
The Clinical Assessment Checklist
The diagnosis of PANDAS is rooted in five clinical criteria established by the National Institute of Mental Health (NIMH). The first requirement is the presence of either Obsessive-Compulsive Disorder (OCD), a tic disorder, or both, as the primary neuropsychiatric manifestation. These symptoms must begin in childhood, specifically between the ages of three and puberty, the period when children are most susceptible to GAS infections.
A defining characteristic distinguishing PANDAS from typical psychiatric disorders is the acute, episodic course of the symptoms. Parents often describe the onset as “explosive” or “overnight,” where symptoms reach their peak severity within 24 to 48 hours, a pattern rarely seen in conventional OCD or tic disorders. The condition is also marked by an association with a preceding Group A Streptococcus infection, which triggers the immune response.
The final criterion involves neurological abnormalities during symptom exacerbations. These can manifest as motoric hyperactivity, small, involuntary jerky movements known as choreiform movements, or other sensory disturbances. While the presence of OCD and tics is mandatory, the sudden, rapid nature of the symptom onset is often considered the most telling clinical indicator.
Supporting Laboratory Investigations
Laboratory tests provide objective evidence of a preceding streptococcal infection, which is a required element of the clinical criteria. The most common tests measure the level of anti-streptococcal antibodies in the bloodstream, known as titers, confirming the body’s immune reaction to the Group A Streptococcus bacteria.
The two primary antibody tests are the Antistreptolysin O (ASO) titer and the Anti-DNase B titer. The ASO titer measures antibodies against the strep enzyme streptolysin O, with levels typically rising three to six weeks after an infection. The Anti-DNase B titer measures antibodies against another strep enzyme and often remains elevated longer, sometimes six to eight weeks post-infection, making it a reliable indicator of recent exposure.
An elevated titer alone only indicates past exposure to strep and does not confirm a PANDAS diagnosis, as antibodies can remain high for months in healthy children. Doctors look for a significant rise in the titer between two blood draws taken several weeks apart, which is strong evidence of a recent infection coinciding with symptom onset. Inflammatory markers like C-reactive protein (CRP) or Erythrocyte Sedimentation Rate (ESR) may also be checked to assess systemic inflammation.
The Importance of Differential Diagnosis
PANDAS is often considered a diagnosis of exclusion, meaning other medical and neurological conditions must be carefully ruled out before the label is applied. This process, known as differential diagnosis, is fundamental to preventing misdiagnosis, as many other disorders share overlapping symptoms, particularly the sudden onset of neuropsychiatric issues.
Conditions such as Sydenham chorea (a post-streptococcal disorder) and Pediatric Acute-onset Neuropsychiatric Syndrome (PANS), which can be triggered by infections other than strep, must be considered. Other mimics include:
- Tourette Syndrome
- Lyme disease
- Various forms of autoimmune encephalitis
- Typical OCD or tic disorders (which usually have a gradual onset)
The physician uses clinical history and laboratory results to determine if a patient’s symptoms are best explained by the PANDAS criteria or by one of these other conditions. This rigorous exclusionary process ensures the child receives the most appropriate and targeted treatment.
Who Confirms the PANDAS Diagnosis
Because PANDAS is a complex condition that bridges pediatrics, neurology, and psychiatry, the diagnosis is typically confirmed by a specialist familiar with neuroimmune disorders. A general pediatrician usually performs the initial screening and orders the necessary strep antibody tests. If suspicion is high, the child is often referred to a specialized practitioner for definitive evaluation.
Specialists commonly involved include pediatric neurologists, child and adolescent psychiatrists, or developmental pediatricians. These professionals have the expertise to synthesize the patient’s acute clinical presentation, immunological test results, and differential diagnosis findings. An immunologist or rheumatologist may also be consulted due to the condition’s autoimmune nature. Confirmation ultimately rests on a specialist’s judgment that the child meets all established clinical criteria and that other plausible conditions have been eliminated.