Overview
The Clinical Problem
Central pontine myelinolysis (CPM) is the classic pontine form of osmotic demyelination syndrome (ODS).
Central pontine myelinolysis (CPM) is the classic pontine form of osmotic demyelination syndrome (ODS). The danger is usually not the low sodium alone; it is the abrupt change in tonicity when long-standing hyponatremia is corrected too quickly. The adapted brain loses water before it can rebuild the organic osmolytes needed to maintain cell volume, and myelin-producing oligodendrocytes are injured. This makes ODS a delayed complication. A patient may become more alert as hyponatremia improves, then develop new dysarthria, dysphagia, weakness, altered consciousness, or paralysis 2–6 days after the sodium rise. That second neurologic decline is not expected recovery and should trigger immediate review of the sodium-correction timeline, urine output, and airway protection.