[Choreic involuntary movement that occurred during therapy for diabetes mellitus].

A 73-year-old woman was admitted with dry mouth, polyposia, polyuria, hyperglycemia (611 mg/dl) and positive urine ketone bodies. Blood glucose levels decreased gradually after initiation of insulin injections. The patient was discharged, but developed involuntary movement of the right extremities on the following day. At that time, her blood glucose levels were 54 mg/dl. Four days later, she was admitted to our Neurology Ward because the movement worsened. On admission, choreic involuntary movements were severe in the right extremities and slight in the left extremities. Urine ketone bodies were negative, but HbA1c had elevated to 11.7%. Although a brain CT did not detect any abnormal density areas, we suspected that the patient had cerebral infarction of the basal ganglia or the parietal lobe on the left side, or of the subthalamic nucleus on the right side because choreic involuntary movements were more prominent on the right side. Anti-platelet therapy was performed, but the involuntary movements persisted. A T1-weighted image of brain MRI, performed on the 4th day after hospitalization, detected abnormal high intensity areas in the bilateral putamens. The abnormal area in the left putamen was more prominent. This MRI finding was consistent with that of diabetic chorea-ballism. Surface electromyography demonstrated the simultaneous appearance of grouping discharges in the biceps and triceps muscles of the right arm. We diagnosed the patient as having diabetic chorea based on the MRI findings, and discontinued anti-platelet therapy. MRI should be performed as soon as possible in diabetic patients with acute-onset chorea-ballism which occurs on one side or predominantly on one side in order to differentiate diabetic chorea-ballism from cerebral infarction.