Sydenham's chorea as a presentation of Moyamoya disease.

A seven year-old male presented to his pediatrician with choreiform movements and a recent history of sore throat. He was diagnosed with Sydenham's chorea based on clinical criteria and laboratory evidence. Worsening symptoms prompted a magnetic resonance imaging (MRI) of the brain which demonstrated evidence of Moyamoya disease. Sydenham's chorea is a common and well-documented complication of post-streptococcal infection, but has not been previously reported in association with Moyamoya disease. This case raises the quandary of causality of chorea in this patient and the need for neuroimaging in children with movement disorders.