Supplementary Material for: Persistent Hemichorea and Caudate Atrophy in Untreated Diabetic Striatopathy: A Case Report E.B.Lucassen W.T.Delfyett M.C.Stahl 2017 <b><i>Background:</i></b> Neurological complications of diabetes and hyperglycemia are relatively common but the specific manifestations can vary widely. Diabetic striatal disease or “diabetic striatopathy” is an uncommon condition usually thought to result from hyperglycemic injury to the basal ganglia, producing a hyperkinetic movement disorder, usually choreiform in nature. Symptoms are generally reversible with treatment of the hyperglycemia. <b><i>Case Description:</i></b> We report the case of a 57-year-old woman presenting with a unilateral choreoathetosis of the left upper extremity, persistent for 4 years. Contemporaneous imaging demonstrated severe atrophy of the right caudate nucleus, while imaging obtained at the onset of symptoms was consistent with a right diabetic striatopathy. Symptoms improved with the use of dopamine antagonists and benzodiazepines. <b><i>Conclusion:</i></b> Although generally considered to be fully reversible, this case demonstrates that diabetic striatopathy can result in permanent structural lesions with persistent symptoms if left untreated.