Non-ketotic hyperglycaemic hemichorea as the first manifestation of undiagnosed diabetes mellitus in an elderly patient.

Summary: Non-ketotic hyperglycaemic hemichorea, also known as diabetic striatopathy (DS), is a rare but reversible hyperglycaemia-related movement disorder. It typically affects elderly patients and may occasionally represent the first manifestation of diabetes mellitus. The hallmark features include involuntary, unilateral choreiform or ballistic movements, with characteristic striatal neuroimaging changes. Early recognition is critical to avoid misdiagnosis and ensure timely intervention. We report a 78-year-old woman with a one-month history of progressive, involuntary right-sided limb movements, which subsided during sleep and severely impaired daily function. She had no prior diagnosis of diabetes but presented with osmotic symptoms for one year. Laboratory tests revealed hyperglycaemia (random blood glucose: 22 mmol/L; HbA1c: 15.9%) without ketosis. Neuroimaging demonstrated hyperdensity in the left caudate and lentiform nucleus on CT and corresponding T1-weighted hyperintensity with asymmetrical striatal atrophy on MRI, consistent with DS. Treatment with insulin, haloperidol, and tetrabenazine achieved a gradual symptomatic improvement, with a marked reduction in involuntary movements at three months, although resolution was protracted compared to the typical cases. This case underscores the importance of considering DS in elderly patients presenting with acute choreiform movements, even in the absence of known diabetes. Awareness of its clinical and radiological features is crucial to prevent misdiagnosis as cerebrovascular disease. While optimal glycaemic control remains the cornerstone of management, persistent or severe cases may require prolonged anti-chorea therapy, reflecting potential irreversible striatal injury. Learning points: DS can occur as the first manifestation of diabetes mellitus. Therefore, hyperglycaemia should be ruled out in patients presenting with chorea, even in the absence of known diabetes. MRI is more sensitive than CT scan in detecting abnormalities in DS, with a reported mismatch rate of 17.5%. However, there is no consistent correlation between the pattern of striatal involvement on the radiological imaging and the distribution of clinical symptoms. Some patients can achieve symptom resolution by glucose control alone. However, the majority require additional anti-chorea medications.