Snapshot A 70-year-old hospitalized patient with a serum sodium of 117 mEq/L is corrected to 140 mEq/L in the next 6 hours. In the subsequent days he becomes paralyzed. Introduction Formerly, called central pontine myelinolysis Caused by severe damage of the myelin sheath of nerve cells, primarily in the brainstem and typically the pons Due to rapid correction of hyponatremia and in liver disease Presentation Symptoms "locked-in" syndrome quadriparesis dysarthria dysphagia other pseudobulbar symptoms Evaluation Imaging minimal changes on CT hyperintense signal on MRI first increase is in the DWI sequence later T2 and FLAIR also increase Treatment Prevention involves slow correction of hyponatremia; at a rate of no more than 8-12mEq/L of sodium per day No treatment once condition has begun