High-signal basal ganglia on T1-weighted images in a patient with Sydenham's chorea.

We report a 16-year-old girl with Sydenham's chorea. Choreiform movements involved both sides of her body. MRI 2 months after the onset revealed abnormal increased signal on T2-weighted images and enlargement of the caudate and putamen bilaterally. MRI 5 months later showed resolution of the swelling, but with increased signal on T1-weighted images in the putamen, globus pallidus and the head of the caudate nucleus bilaterally, with slightly increased signal intensity on T2-weighted images.