PANS (Pediatric Acute-onset Neuropsychiatric Syndrome) is a condition characterized by a sudden, severe shift in a child’s mental and behavioral state, typically following an infection. The syndrome is defined by the abrupt appearance of obsessive-compulsive disorder (OCD) or significant food restriction, alongside other severe neuropsychiatric symptoms. There is no single, definitive test for PANS. Diagnosis relies instead on a comprehensive process that combines clinical observation, detailed patient history, laboratory results, and the exclusion of other possible medical conditions.
The Clinical Basis of Diagnosis
The diagnosis of PANS is primarily clinical, made by a healthcare provider based on observable symptoms and a thorough medical history, not solely on lab results. The process follows criteria established by the National Institute of Mental Health (NIMH) and requires a detailed timeline of symptom onset. The most distinguishing feature is the dramatic, acute onset of symptoms, often allowing parents to pinpoint the exact day the child’s behavior changed.
The first requirement is the abrupt, severe onset of either obsessive-compulsive disorder (OCD) or severely restricted food intake. This dramatic change differentiates PANS from typical, gradual-onset psychiatric conditions. The sudden development of new rituals or a phobia-like refusal to eat certain foods forms the core of the diagnosis.
The second part of the criteria demands the concurrent presence of additional neuropsychiatric symptoms that also appeared with acute and severe onset. These associated symptoms must be present in at least two of seven specific categories.
A clinician looks for symptoms across seven categories, including:
- Separation anxiety
- Emotional lability or depression
- Severe oppositional behaviors or aggression
- Behavioral regression
- Deterioration in school performance
- Motor or sensory abnormalities
- Somatic symptoms, such as sleep disturbances or increased urinary frequency
The diagnosis is confirmed when these criteria are met and the symptoms cannot be better explained by another neurological or medical disorder.
Laboratory Investigations
Laboratory testing plays a supporting role by investigating potential infectious triggers and assessing the body’s inflammatory response. These tests do not confirm the syndrome but provide objective evidence that supports the clinical picture and guides treatment decisions. The primary focus is identifying infectious agents that may have preceded the neuropsychiatric symptoms.
Testing for Strep (PANDAS)
For PANDAS, a subset of PANS linked to Group A Streptococcus (GAS), doctors check for evidence of recent strep infection using Antistreptolysin O (ASO) and Anti-DNase B titers. These blood tests measure antibodies produced against the strep bacteria, indicating a past or recent infection. Elevated titers suggest the immune system was recently activated by strep, a key component of PANDAS.
Broader Infectious and Inflammatory Markers
PANS can be triggered by a range of pathogens, necessitating a broader lab workup for agents like Mycoplasma pneumoniae, Lyme disease, and various viruses. General inflammatory markers, such as the Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP), are also frequently ordered. A high result can point toward an active inflammatory process, though these markers are not always elevated in PANS.
Immune System Evaluation
Specialized immune panels may evaluate the overall function of the immune system. This includes measuring quantitative immunoglobulins (IgG, IgA, IgM) and Antinuclear Antibodies (ANA), which can indicate an autoimmune or immunodeficiency issue. Some clinicians utilize proprietary panels, like the Cunningham Panel, which tests for specific antibodies that may target brain tissue.
Ruling Out Mimics
The diagnostic pathway requires differential diagnosis, which involves ruling out other conditions that present with similar acute neuropsychiatric changes. PANS is a diagnosis of exclusion, meaning it is only confidently made after a provider has systematically eliminated other potential medical causes. This step is necessary because several other conditions, some of which are life-threatening, can mimic PANS symptoms.
Conditions such as autoimmune encephalitis, central nervous system vasculitis, and metabolic disorders must be considered and excluded. These conditions involve inflammation or dysfunction in the brain and can cause rapid changes in behavior, mood, and cognitive function. The exclusion process ensures the child receives the most appropriate treatment for an alternative diagnosis.
To exclude these neurological conditions, ancillary tests like brain imaging, typically Magnetic Resonance Imaging (MRI), and electroencephalograms (EEG) are often employed. An MRI checks for structural abnormalities, tumors, or signs of inflammation characteristic of other disorders. An EEG, which records electrical activity, helps rule out seizure disorders that could manifest as behavioral changes. In many PANS cases, these tests are normal, which strengthens the diagnosis by eliminating structural and electrical abnormalities as the primary cause.