Central Pontine Myelinolysis is also called Osmotic demyelination syndrome.
https://www.nlm.nih.gov/medlineplus/ency/article/000775.htm
“The most common cause of central pontine myelinolysis is a quick change in the body’s sodium levels. This most often occurs when someone is being treated for low blood levels of sodium (hyponatremia) and the sodium is replaced too fast. It also can occasionally occur when high levels of sodium in the body (hypernatremia) are corrected too quickly.
This condition does not usually occur on its own. It is typically a complication of treatment for other conditions, or from the other conditions themselves.”