Paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS)

The evidence to date. both published and unpublished, which addresses the v alidity of the proposed unique subgroup of children with early and abrupt o nset of obsessive-compulsive disorder (OCD) and/or tic disorders subsequent to streptococcal infections was reviewed. The aetiology of OCD and tic dis orders is unknown, although it appears that both disorders may arise from a variety of genetic and environmental factors. Post-streptococcal autoimmun ity has been postulated as one possible mechanism for some. The acronym PAN DAS (for paediatric autoimmune neuropsychiatric disorders associated with s treptococcal infections) has been given to a subgroup of paediatric patient s who meet five inclusionary criteria: presence of OCD and/or tic disorder, pre-pubertal symptom onset, sudden onset or episodic course of symptoms, t emporal association between streptococcal infections and neuropsychiatric s ymptom exacerbations, and associated neurological abnormalities. The propos ed model of pathophysiology provides for several unique treatment strategie s, including the use of antibiotic prophylaxis to prevent streptococcal-tri ggered exacerbations, and the use of immunomodulatory interventions (such a s intravenous immunoglobulin or therapeutic plasma exchange) in the treatme nt severe neuropsychiatric symptoms. For the latter study group, long-term (2-5 yr) follow-up revealed continued symptom improvement for the majority of patients, particularly when antibiotic prophylaxis had been effective in preventing recurrent streptococcal infections. In addition, the episodic n ature of the subgroup's illness provides for opportunities to study brain s tructure and function during health and disease, as well as allowing for in vestigations of the aetiologic role of anti-neuronal antibodies and neuroim mune dysfunction in both OCD and tic disorders. Although much research rema ins to be done, an increasing body of evidence provides support for the pos tulate that OCD and tic disorders may arise from post-streptococcal autoimm unity. The unique clinical characteristics of the PANDAS subgroup, the pres ence of volumetric changes in the basal ganglia, and the dramatic response to immunomodulatory treatments, suggest that symptoms arise from a combinat ion of local, regional and systemic dysfunction. Ongoing research is direct ed at understanding the nature of the abnormal immune response, as well as identifying at-risk children, in order to provide for novel strategies of p revention and treatment.