Hyperglycemic choreoathetosis: role of the putamen in pathogenesis

Hyperglycemic choreoathetosis (HC) is an uncommon syndrome often associated with hyperintensity of the basal ganglia on MRI. We performed a retrospective review of cases with HC to characterize the clinical, biochemical, and neuroimaging (CT, MRI, and MR spectroscopy) findings and to propose a mechanism for this syndrome. Seven HC patients with a mean age of 75.1 years, mean blood glucose of 27.4 mmol/L, and mean plasma osmolarity of 313.4 mmol/L were studied. All had MR-T1 hyperintensity of the putamen on the side contralateral to the choreoathetosis. Two patients had additional hyperintensity of the globus pallidus while one also had involvement of the caudate. On MR-T2, 2 patients showed hyperintensity, 2 isointensity, and 3 hypointensity in the putamen. MR spectroscopy showed elevated choline and reduced N-acetylaspartate; two patients also had elevated myoinositol levels. Our findings suggest that the putamen has a central role in HC, and MR spectroscopy supports neuronal dysfunction in the putamen. Biochemical and neuroimaging findings support hyperviscosity as the most plausible mechanism.