Isolated bipallidal lesions caused by extrapontine myelinolysis

An 89-year-old woman developed bradykinesia, mutism, and apathy after a rapid correction of hyponatremia caused by repeated vomiting. Brain MRI showed bipallidal involvement that improved at follow-up (figure 1, figure 2). The patient’s clinical history and neuroimaging are suggestive of extrapontine myelinolysis. This disease involves basal ganglia but the globus pallidus is usually spared or not singly involved.1 A patient with bipallidal extrapontine myelinolysis has been previously described.2 Toxic, hypoxic, and metabolic causes of bipallidal involvement were excluded in our patient. Extrapontine myelinolysis should be included in the differential diagnosis of patients with a history of hyponatremia, subacute parkinsonism, and bipallidal lesions on MRI.