PANDAS

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) is a controversial hypothetical diagnosis for a subset of children with rapid onset of obsessive–compulsive disorder (OCD) or tic disorders coming immediately after a Streptococcus infection. Symptoms are proposed to be caused by group A streptococcal (GAS), and more specifically, group A beta-hemolytic streptococcal (GABHS) infections. OCD and tic disorders are hypothesized to arise in a subset of children as a result of a post-streptococcal autoimmune process. The proposed link between infection and these disorders is that an autoimmune reaction to infection produces antibodies that interfere with basal ganglia function, causing symptom exacerbations, and this autoimmune response results in a broad range of neuropsychiatric symptoms. The PANDAS hypothesis, first described in 1998, was based on observations in clinical case studies by Susan Swedo et al. at the US National Institute of Mental Health and in subsequent clinical trials where children appeared to have dramatic and sudden OCD exacerbations and tic disorders following infections. Whether PANDAS was a distinct entity differing from other cases of tic disorders or OCD is debated. As the PANDAS hypothesis was unconfirmed and unsupported by data, a new definition was proposed by Swedo and colleagues in 2012. In addition to the 2012 broader pediatric acute-onset neuropsychiatric syndrome (PANS), two other categories have been proposed: childhood acute neuropsychiatric symptoms (CANS) and pediatric infection-triggered autoimmune neuropsychiatric disorders (PITAND). The CANS/PANS hypotheses include different possible mechanisms underlying acute-onset neuropsychiatric conditions, but do not exclude GAS infections as a cause in a subset of individuals. PANDAS, PANS and CANS are the focus of clinical and laboratory research but remain unproven. There is no diagnostic test to accurately confirm PANDAS; the diagnostic criteria are unevenly applied and the conditions may be overdiagnosed. Treatment for children suspected of PANDAS is generally the same as the standard treatments for Tourette syndrome (TS) and OCD. There is insufficient evidence or consensus to support treatment, although experimental treatments are sometimes used, and adverse effects from unproven treatments are expected. The media and the internet have contributed to an ongoing PANDAS controversy, with reports of the difficulties of families who believe their children have PANDAS or PANS. Attempts to influence public policy have been advanced by advocacy networks.

Characteristics The children originally described by Susan Swedo et al. (1998) usually had an abrupt onset of symptoms, including motor or vocal tics, obsessions, or compulsions. In addition to an obsessive–compulsive or tic disorder diagnosis, children may have other symptoms associated with exacerbations such as emotional lability, enuresis, anxiety, and deterioration in handwriting. There may be periods of remission. In the PANDAS model, this abrupt onset is thought to be preceded by a strep throat infection. As the clinical spectrum of PANDAS appears to resemble that of Tourette syndrome (TS or TD, for Tourette's disorder), some researchers hypothesized that PANDAS and TS may be associated; this idea is challenged and a focus for research. Pediatric acute-onset neuropsychiatric syndrome (PANS) is a hypothesized disorder characterized by the sudden onset of OCD symptoms or eating restrictions, concomitant with acute behavioral deterioration or severe neuropsychiatric symptoms including sleep, emotional and behavioral disturbances, regression in school performance, or motor and sensory issues. PANS eliminated tic disorders as a primary criterion and placed more emphasis on acute-onset OCD, while allowing for causes other than streptococcal infection.

Classification

PANDAS is hypothesized to be an autoimmune disorder that results in a variable combination of tics, obsessions, compulsions, and other symptoms with sudden or abrupt onset that may be severe enough to qualify for diagnoses such as chronic tic disorder, OCD, and TS. As of 2024, the autoimmune hypothesis of PANDAS is controversial and disputed. PANS, CANS and PITANDs are also hypothesized to be autoimmune disorders.

Cause The PANDAS diagnosis and the hypothesis that symptoms in this subgroup of patients are caused by infection are disputed and unconfirmed. The cause is thought to be akin to that of Sydenham's chorea (SC), which is known to result from childhood group A streptococcal (GAS) infection leading to the autoimmune disorder rheumatic fever of which SC is one manifestation. Like SC, PANDAS is thought to involve autoimmunity to the brain's basal ganglia. To establish that a disorder is an autoimmune disorder, the Witebsky criteria require

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