[A child with choreic movement, generalized convulsion and severe neurological deterioration responded to cyclophosphamide].

A 3-year-old girl developed right hemiplegia with acute onset, followed by generalized convulsion, choreic movement, and severe motor deterioration. She became bed-ridden a few months after the onset. Intravenous cyclophosphamide pulse therapy resulted in a remarkable improvement of her clinical symptoms. At age of six, she has recovered markedly with the residual symptom of minimum dysarthria. Autoimmune mechanism similar to the antiphospholipid syndrome was considered to be the pathogenesis of this case.