The term Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) describes the clinical presentation of a subset of pediatric onset Obsessive-Compulsive Disorder (OCD). PANS may also be a subset of Avoidant/Restrictive Food Intake Disorder (ARFID).
While the criteria for diagnosing PANS do not specify a trigger, the syndrome is thought to be an immune reaction to one of a number of physiological stressors including Group A Streptococcal infection, Mycoplasma pneumonia infection, influenza, upper respiratory infections, sinusitis, and psychosocial stresses. PANDAS (Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infections) is a subset of PANS where symptom onset and exacerbations are triggered by Group A Streptococcal infections.
The diagnosis of PANS should be considered whenever symptoms of OCD, eating restrictions or tics start suddenly, and are accompanied by other emotional and behavioral changes, frequent urination, motor abnormalities and/or handwriting changes.
PANS is presently thought to result from dysfunction of the basal ganglia (specifically, the caudate, putamen and globus pallidus). One theory of PANS proposes that serum antibodies cross the blood brain barrier, cross-react with neuronal antigens and dysregulate basal ganglia functions. Another theory suggests that neuroglial immune cells in the brain incite basal ganglia inflammation. Neurons connecting to the basal ganglia affect motor function, emotion, behaviors, procedural learning, cognition and sensory issues (TABLE 1).
PANDAS is thought to be similar in etiology to Sydenham Chorea (a manifestation of acute rheumatic fever). Approximately 30% of Acute Rheumatic Fever (ARF) patients have Sydenham Chorea; of those, about 70% will develop OCD. Like Sydenham Chorea, PANDAS may result from the molecular mimicry of Group A streptococcal bacteria, which stimulates production of antibodies that then cross-react with antigens in the brain, producing a variety of neurologic and psychiatric manifestations.