[Hemichorea-hemiballism associated with nonketotic hyperglycemia and presenting with unilateral hyperintensity of the putamen on MRI T1-weighted images--a case report].

A 74-year-old man was admitted to our hospital with abrupt onset of hemichorea-hemiballism in the left arm and leg. On admission, the blood glucose level was 296 mg/dl, glycosylated hemoglobin Alc was 17.0%, and the serum osmolality was 296 mOsm/l. Urinalysis was negative for ketone bodies, but was strongly positive for glucose. After normalization of the blood glucose level, ballistic movement disappeared, but choreiform movement of the left arm and leg continued for 10 months. Brain CT showed a slight high density of the right putamen, which disappeared on 37th day after the onset. MRI showed high intensity on T1-weighted images and low intensity on T2-weighted images in the right putamen, which disappeared 10 months after the onset. SPECT on the 21th day after the onset showed hyperperfusion in the right putamen. 4 months later, the blood flow slightly reduced in the right putamen. The abnormality in the right putamen was considered to be the cause of his involuntary movements. High intensity in the putamen on T1-weighted MR images in the present case are presumed to have developed following mild ischemia and the reversible deposition of calcium or other material which occurred in association with nonketotic hyperglycemia.