Clinical case of anti-N-methyl-D-aspartate receptor encephalitis in an 8-month-old patient with hyperkinetic movement disorder.

This article describes an 8-month-old boy with the full clinical spectrum anti-N-methyl-d-aspartate receptor encephalitis. He was admitted to the hospital with involuntary orofacial head movements, behavioral changes, and fluctuation in consciousness. His examination showed tongue thrusting, decreased responsiveness, and hypotonia without fever. Analysis of the cerebrospinal fluid revealed increased protein levels (62 mg/dL). The next day he developed oral dyskinesia and choreoathetosis. Video-electroencephalogram polygraphy showed coreo-dystonic movements without electrographic correlation. A putative diagnosis of autoimmune encephalopathy was made, and treatment with intravenous immunoglobulin and methylprednisolone was started, with improvement in the abnormal movements. Antibodies to the N-methyl-d-aspartate receptor were identified in the cerebrospinal fluid and blood. He began receiving immunoglobulin once a month for a year. Two months after the treatment had started, the involuntary movement disappeared and his development has been normal. N-methyl-d-aspartate receptor encephalitis is a recently identified disorder. This is the youngest case reported. Prompt diagnosis and treatment are important to obtain full recovery.