I often wonder if the obsession amongst physicians regarding the prevention of Osmotic Demyelination Syndrome (ODS or Central Pontine Myelinolysis – CPM) results in adverse patient outcomes – for example a greater incidence of iatrogenic complications, prolonged length of stay etc.

In this discussion, I look at the history of ODS/CPM, how it became identified with rapid correction of hyponatremia and what patients are at particular risk of this disorder. In the second part of the discussion I address the re-ignited controversy about Sodium/Osmolality correction subsequent to the publication of a major study in NEJM Evidence in 2023.

Ultimately each clinician must make up their own minds on the evidence that is available. It appears to me that there is little or no risk of ODS/CPM in patients with acute hyponatremia, symptomatic or not, and those with a plasma sodium of greater than 120mmol/L. Patients with Sodium levels below 105mmol/L, alcoholics or cirrhotics and malnourished patient appear to be at very high risk. Finally attention should be paid not only to the speed of correction, but where the plasma sodium levels ends up. In many studies – ODS/CMP is a late diagnosis and patients, at the time of diagnosis are hypernatremic (greater than 145mmol/l) – although the rise in Sodium/Osmolality may appear slow over days or weeks.