Extrapontine myelinolysis, a fairly common metabolic disorder, is associated with neurological complications. Central pontine and extrapontine myelinolysis are commonly recognized with rapid correction of sodium. Myelinolysis, however, has rarely been described with hypernatremia. We report a rare case of post-partum hypernatremic encephalopathy associated with serum sodium levels as high as 200 mEq/l on presentation. Although the serum sodium levels were brought down gradually, subsequent imaging showed progression of demyelination and deterioration of the neurological status.