Diabetic Hemichorea-hemiballism

Hemichorea/hemiballism (HC/HB) associated with nonketotic hyperglycemia (NKH) and hyperintense putamen on T1 weighted MRI has been recognized as a clinical entity, but the substrate responsible for the MRI signal changes and the pathogenesis of HC/HB remain unsettled. This syndrome is relatively rare, but its recognition is important because the correction of hyperglycemia usually leads to prompt clinical and radiological improvement, and occasionally to the detection of untreated diabetes mellitus. In this review, the clinical, radiological, and pathological features of this syndrome are extensively described with reference to possible underlying mechanisms.