Hemichorea associated with nonketotic hyperglycemia: A case report with unremarkable neuroimaging at presentation.

Nonketotic hyperglycemic hemichorea is a rare neurological disorder. Neuroimaging may provide supportive evidence, typically demonstrating contralateral basal ganglia abnormalities corresponding to the side of involuntary movements. However, characteristic findings may be absent or highly subtle in some patients, which can complicate recognition and delay diagnosis. Herein, we report the case of a 76-year-old woman without a known history of diabetes mellitus who presented with a 7-day history of involuntary choreiform movements of the right hand. On admission, initial brain computed tomography was interpreted as unremarkable; however, retrospective review revealed a subtle, faint hyperdensity in the left striatum. Magnetic resonance imaging, including diffusion-weighted imaging, showed no obvious characteristic signal changes in the basal ganglia. Laboratory testing demonstrated marked hyperglycemia without ketosis. After alternative etiologies were excluded, the presentation was considered most consistent with nonketotic hyperglycemic hemichorea based on the clinical syndrome and metabolic profile. The patient's symptoms improved markedly after intensive glycemic control with insulin therapy. This case highlights that nonketotic hyperglycemic hemichorea should be considered in patients with acute hemichorea and hyperglycemia, even when neuroimaging initially appears unremarkable, and that prompt glycemic management remains the cornerstone of treatment.