[Repeated hyperglycemic hemichorea in a patient with venous angioma in the putamen].

We report a case of an 81-year-old diabetic woman who had three episodes of choreic involuntary movement in the left extremities. Brain CT revealed faintly increased density in the right putamen. On MRI performed 28 days after onset of the left hemichorea, the right putamen showed increased signal intensity on T1-weighted images and the so-called "medusa-like appearance" of medullary venous drainage into the thalamostriate vein on enhanced T1-weighted images. These findings indicated petechial hemorrhage of the right putamen from a venous angioma. We hypothesize that this hemorrhagic change due to a venous malformation in the basal ganglia may induce involuntary movements in diabetic patients during severe hyperglycemia.