[MRI study of hemiballism].
MRI findings of four hemiballism cases are described, and pathophysiology, pathogenesis and treatment of hemiballism are discussed. All cases had no family history. The lesions revealed by MRI and the pathogenesis were different each other. Case 1, a 17 years aged girl with a history of hyperthyroidism and repeated tonsillitis, showed right sided hemiballism which was recovered by prednisolone and haloperidol. Although her involuntary movement was ameliorated by administration of sodium valproate and phenytoin, phenytoin caused allergic agranulocytosis which required prednisolone treatment. T2 weighted MRI at the 31st disease day demonstrated hyperintensities in the left caudate nucleus, putamen, lateral pallidum, perirubral area and substantia nigra. Hyperintensity in the prerubral area suggested involvement of the subthalamic nucleus or its connecting pathway. Fourteen months later, she suffered from convulsion and mental confusion. There were theta wave bursts and delta waves in EEG. No abnormal findings in MRI and positive antinuclear antibody (ANA: X320, speckled type) were observed. Case 2, a 78 year aged woman, suffered from right sided hemiballism. MRI findings at the 58th disease day were the left putaminal infarction and lacunar state in the bilateral caudate nuclei and the deep white matter of the centrum semiovale. There were no abnormal findings in the subthalamic nucleus. Case 3, a 51 year aged man with diabetes mellitus, had right sided hemiballism. X-ray CT at the 8th disease day showed hyperdensity in the left subthalamic nucleus region which could not be observed at the 12th day. Hypointensity in the left subthalamic nucleus region was observed in both T2 weighted and proton density MRI at the 52nd day. Case 4, an 82 year aged woman, had right sided hemiballism which remarkably diminished at the third disease day and disappeared by the fifth day. Any pathogenic lesion concerning to hemiballism was detected by X-ray CT or MRI.(ABSTRACT TRUNCATED AT 250 WORDS)