Hemichorea-Hemiballismus as A First Presentation of Diabetes: Basal Ganglia Involvement and Hba1c Threshold

We report a case of a 72-year-old woman who presented with a one-week history of abnormal, involuntary movements in her left upper limb. These movements were persistent throughout the day, occurring during both activity and sleep, and had progressively increased in intensity since onset. She also experienced weakness in the affected arm. Her past medical history included hypertension, managed with Amlodipine 5 mg once daily. On examination, she exhibited continuous, involuntary, flinging movements of the left arm, consistent with hemiballism. The rest of her neurological examination was unremarkable, and cerebellar signs could not be assessed due to the involuntary movements. Her blood pressure on admission was 202/81 mmHg. Random blood glucose was 27 mmol/L, with ketones at 0.8 mmol/L and serum osmolality at 285 mOsm/kg. She was managed as a case of hyperosmolar hyperglycemic state. Investigations showed an HbA1c of 18.6%. A head computed tomography (CT) revealed no intracranial abnormalities, while magnetic resonance imaging (MRI) showed tiny hypodensities in the left ganglio-capsular region and small hypointensities in the right ganglio-capsular area and this not stroke. Treatment with Risperidone successfully resolved the chorea. Her blood pressure and blood glucose were optimized, and she was discharged in stable condition. Hemichorea-hemiballismus as the first presentation of diabetes is extremely rare. Most case reports indicate an HbA1c of 12% or higher can be associated with hyperglycemia-induced hemichorea-hemiballismus (HIHH). Further research is needed to clarify the mechanisms underlying HIHH and to determine a definitive HbA1c threshold.