Following tonsillectomy, his obstructive sleep apneas and ocular-facial tics underwent complete remission. syndromes (CANS), Bitopertin (R enantiomer) two new concepts recently proposed in order to define a much broader clinical spectrum encompassing etiologically diverse entities. Given the uncertainties on the clinical definition of PANDAS, it is not surprising that evidence in support of a post-infectious, immune-mediated pathophysiology is also insufficient. Anti-dopamine receptor antibodies might be relevant to both Sydenhams chorea (SC)the prototypical post-streptococcal neuropsychiatric disorderand some rare forms of encephalitis targeting the basal ganglia specifically, but studies exploring their association with children fulfilling Swedos criteria for PANDAS have been inconclusive. Moreover, we lack evidence in favor of the efficacy of antibiotic prophylaxis or tonsillectomy in patients fulfilling Swedos criteria for PANDAS, whereas a response to immune-mediated treatments like intravenous immunoglobulins has been documented by one study, but needs replication in larger trials. Overall, the available evidence does not convincingly support the concept that PANDAS are a well-defined, isolated clinical entity subdued by definite pathophysiological mechanisms; larger, prospective studies are necessary to reshape the nosography and disease mechanisms of post-streptococcal acute neuropsychiatric disorders other than SC. Research is also under way WASL to shed further light on a possible relationship between streptococcal infections, other biological and psychosocial stressors, and the complex pathobiology of chronic tic Bitopertin (R enantiomer) disorders. Keywords:Group-A beta-hemolytic streptococcal infection, autoimmunity, PANDAS, PANS, CANS, Tourette syndrome, obsessive-compulsive symptoms == Introduction == The term pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections Bitopertin (R enantiomer) (PANDAS) refers to children with abrupt onset of tics and/or obsessive-compulsive symptoms (OCS) associated with a recent group-A beta-hemolytic streptococcal (GABHS) infection.1Sydenhams chorea (SC), a well-characterized manifestation of rheumatic fever (RF), is considered the prototype of neurologic disorders caused by aberrant immune responses to GABHS. SC patients Bitopertin (R enantiomer) often exhibit OCS together with other behavioral abnormalities. This contributed to the hypothesis that SC and PANDAS might be two distinct presentations of cortico-subcortical network dysfunction triggered by GABHS. Molecular mimicry, in which antibodies targeting bacterial antigens cross-react with brain (basal ganglia) antigens, was proposed as the pathogenic basis of post-streptococcal neuropsychiatric disorders.2,3 PANDAS have become a popular concept among patients, clinicians, and researchers. However, their clinical definition and prevalence are still debated. During the last 15 years, several limitations of the working diagnostic criteria for PANDAS have been highlighted. Moreover, different attempts to ascertain their frequency within the general population of youths with tics and OCS were not successful. Reliable diagnostic biomarkers are still not available and their pathogenesis remains undefined. This led to a recent nosographic reappraisal of PANDAS, implying that further work is needed to define the medical boundaries of post-streptococcal disorders within the rubric of acute pediatric neuropsychiatric symptoms. With this review, we summarize the main points of argument round the medical and pathophysiological features of PANDAS, with additional considerations within the possible part of infections and immunity in the natural history of tic disorders. == Brief historic preface == In his monograph On Chorea and Choreiform Affectations (1894), Osler 1st explained obsessive-compulsive behavior in SC. Half a century later on, this observation was confirmed in larger case series.4,5In 1965, Langlois and Force reported inside a 6-year-old Bitopertin (R enantiomer) the coexistence of tics and SC precipitated by infections, subsequently treated successfully with antibiotics and neuroleptics. In 1978, Kondo and Kabasawa reported in an 11-year-old son a tic disorder started abruptly about 10 days after a febrile illness associated with elevated antistreptolysin O (ASO) antibody titers and good response to corticosteroids;6this case prompted the discussion within the role of biological stressors in tic disorders, representing relevant background information for the first description of PANDAS. Kiessling7reported an association of tics during pediatric GABHS outbreaks..