Osmotic Demyelination

A 52-year-old man with chronic alcohol use disorder presents with severe hyponatremia (sodium 108 mmol/L) from beer potomania. He is treated with hypertonic saline, and his serum sodium is corrected to 128 mmol/L over 12 hours. Initially, his seizures and altered mentation improve. However, 3–4 days later, he develops progressive neurologic deterioration with dysarthria, dysphagia, quadriparesis, and locked-in syndrome. MRI brain shows symmetric hyperintensity in the central pons with a characteristic bat-wing appearance, and restricted diffusion on DWI. The structure marked **C** in the diagram represents the pathologic finding in this patient. Which of the following best describes the mechanism by which rapid sodium correction led to this lesion?