We report a case of suspected pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) in a 14-year-old adolescent male. The patient developed sudden onset and acute exacerbation of vocal and motor tics and obsessive-compulsive symptoms that caused significant difficulty in daily life, necessitating admission to the psychiatric department. We performed blood tests, magnetic resonance imaging of the brain, single-photon emission computed tomography to evaluate cerebral blood flow, electroencephalography, and cerebrospinal fluid (CSF) examination including a CSF viral antibody test, revealing no abnormalities. However, a CSF oligoclonal band screen showed positive results (two CSF bands). Detailed medical history taking revealed that the patient had developed sore throat with profuse nasal discharge 1-2 weeks before the onset of PANDAS symptoms. Notably, streptococcal infection was prevalent in the school environment at that time. Based on progressive tics and obsessive-compulsive symptoms observed after the infection, we suspected PANDAS and initiated massive intravenous immunoglobulin (IVIG) therapy. No improvement occurred following the first course of treatment; however, reduced numbers of CSF oligoclonal bands were observed. It was concluded that this therapeutic approach had effectively treated inflammation of the brain; thus, we administered a second course of IVIG combined with steroid pulse therapy. The patient's symptoms rapidly improved after treatment. A second course of steroid pulse therapy was administered. Following this, the patient could converse fluently and required less time for eating and bathing activities. The patient's tics and obsessive-compulsive symptoms showed near-complete remission following an additional course of steroid pulse therapy, and he was discharged. One year after discharge, the patient experienced mild but temporary recurrence of tics and obsessive-compulsive symptoms; however, these resolved in 3 months. One year after symptom resolution, the patient again experienced tics and obsessive-compulsive symptoms. Steroid pulse therapy and IVIG therapy were performed once more. The patient was in remission two months later. The importance of detailed clinical history taking including information regarding streptococcal infections is emphasized. Immunological examination of CSF is important to accurately diagnose PANDAS, and immunotherapy including steroid pulse therapy may be useful for treatment.
 Authors' abstract