Paroxysmal Hemidystonia as the Presenting Manifestation of Previously Undiagnosed Diabetes Mellitus

Background: Hyperglycemia-related movement disorders classically present as hemichorea-hemiballismus, whereas dystonia is far less common and may occasionally precede the recognition of diabetes mellitus. Case Report: A 72-year-old man presented with a 3-month history of recurrent, stereotyped dystonic spells involving the right side of the face, arm, and leg. These episodes occurred approximately twice per minute and lasted about 5 seconds each. Initial laboratory testing revealed a plasma glucose level of 494 mg/dL and an HbA1c of 16.1%, consistent with previously unrecognized diabetes mellitus. Electrolyte levels, electroencephalography, cerebrospinal fluid analysis, and evaluation for autoimmune encephalopathy were unremarkable. Brain MRI showed only a chronic lacunar infarct in the left basal ganglia, with no evidence of an acute striatal lesion. The abnormal movements resolved completely within 3 days after correction of hyperglycemia. Follow-up 18F-FDG PET/CT performed after clinical recovery demonstrated subtle relative hypometabolism in the left cerebellum, with preserved uptake in the basal ganglia and cerebral cortex. Discussion: This case broadens the phenomenologic spectrum of hyperglycemia-related movement disorders and highlights paroxysmal hemidystonia as a potential presenting manifestation of previously undiagnosed diabetes mellitus. Bedside glucose testing should therefore be routinely performed in the evaluation of new-onset paroxysmal hyperkinetic movements. In addition, isolated extra-striatal metabolic abnormalities detected after symptom resolution should be interpreted with caution.