Case study: acute basal ganglia enlargement and obsessive-compulsive symptoms in an adolescent boy.

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAs) may arise when antibodies directed against invading bacteria cross-react with basal ganglia structures, resulting in exacerbations of obsessive-compulsive disorder (OCD) or tic disorders. This is a report of severe worsening of obsessive-compulsive symptoms in an adolescent boy following infection with group A beta-hemolytic streptococci for whom serial magnetic resonance imaging scans of the brain were acquired to assess the relationship between basal ganglia size, symptom severity, and treatment with plasmapheresis. These data provide further support for basal ganglia-mediated dysfunction in OCD and the potential for immunological treatments in PANDAs patients.