Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) is a condition where a Group A Streptococcus (GAS) infection appears to trigger the sudden onset of neuropsychiatric symptoms in children. The illness is theorized to be an autoimmune response where the body’s antibodies, created to fight the strep bacteria, mistakenly attack parts of the brain, specifically the basal ganglia. Understanding how to test for PANDAS begins with recognizing that no single blood test can definitively confirm the diagnosis. Instead, PANDAS is considered a clinical diagnosis, relying on a set of five specific criteria observed by a physician, which are then supported by laboratory evidence of a recent or current strep infection.
Required Clinical Criteria for Diagnosis
The first component of diagnosing PANDAS is the presence of Obsessive-Compulsive Disorder (OCD) and/or tics. These symptoms must be severe enough to interfere significantly with the child’s functioning, often manifesting as complex or unusual motor or vocal tics. The most distinctive feature of PANDAS is the unusually abrupt and dramatic onset of these neuropsychiatric symptoms, appearing suddenly and often reaching peak severity within days, contrasting sharply with the gradual onset seen in other psychiatric disorders.
The patient must also exhibit an episodic, relapsing-remitting course, where symptoms flare up and then potentially resolve or lessen, often coinciding with subsequent strep infections. The onset of symptoms must occur during the prepubertal period (typically ages three to puberty), a time of high exposure to Group A Strep infections.
A third criterion requires a temporal association with a Group A Beta-Hemolytic Streptococcal (GABHS) infection. The initial onset or subsequent exacerbations must closely follow a documented strep infection. Finally, the child must display associated neurological abnormalities, which can include motoric hyperactivity, small, jerky movements known as choreiform movements, or other signs of motor dysregulation. The explosive onset of these symptoms, combined with the presence of other issues like severe anxiety, emotional lability, or urinary frequency, helps differentiate PANDAS from typical childhood-onset OCD or tic disorders.
Supporting Laboratory Tests
While the clinical presentation is paramount, laboratory tests are used to provide the necessary evidence of a strep infection or immune response. The most immediate tests check for a current infection, including a rapid strep test and a throat culture. A throat culture is considered more reliable, especially when looking for colonization, and a 24-48 hour agar culture may be recommended.
To confirm a recent past infection, physicians rely on anti-streptococcal antibody titers, specifically the Anti-streptolysin O (ASO) titer and the Anti-DNase B titer, which measure antibodies produced in response to strep toxins. The ASO titer typically peaks about two to four weeks after the initial infection, while the Anti-DNase B titer rises more slowly, peaking around six to eight weeks post-infection and remaining elevated longer.
A single elevated titer only confirms a recent exposure, not necessarily a current infection or a definitive link to the neuropsychiatric symptoms. Clinicians often look for a significant rise, such as a two- to four-fold increase, between an acute sample and a convalescent sample taken several weeks later, which is more suggestive of a recent infection. A normal titer result does not completely rule out PANDAS, as some children with documented strep infections do not show a rise in these antibody levels. These tests serve as supporting evidence for the clinical picture, rather than a standalone diagnostic tool.
Navigating the Diagnostic Process
The diagnostic journey for PANDAS is a complex process that requires a comprehensive medical history and a multidisciplinary approach. A pediatrician is typically the first point of contact, collaborating with specialists like child psychiatrists, neurologists, or immunologists. The psychiatrist assesses the severity of new-onset OCD or tics, while the pediatrician focuses on identifying the infectious trigger.
A crucial part of this process is differential diagnosis, which involves ruling out other conditions that can present with similar symptoms, such as Sydenham chorea, Tourette Syndrome, or other forms of Pediatric Acute-onset Neuropsychiatric Syndrome (PANS). Sydenham chorea is a post-streptococcal autoimmune disorder, but it presents with a distinct movement disorder. PANS is a broader diagnosis that includes triggers other than strep, such as other infections or inflammatory reactions.
The typical steps involve the initial clinical observation of the acute, dramatic onset of symptoms, followed by ordering the supporting lab work for strep exposure. If the clinical criteria are met and the labs confirm recent strep, the diagnosis is strongly supported, although some cases require consultation with an immunologist to explore potential immunomodulatory treatments. The final diagnosis is a synthesis of the observed clinical pattern and the laboratory evidence, guiding the subsequent treatment plan.