CPM and ODS

Q: Why "central pontine myelinolysis (CPM)" is not a correct term as a neurological complication in overly rapid correction of hyponatremia?

Answer: Previously, CPM was used for decades to describe the neurological complication of overly rapid correction of hyponatremia. But there are two reson the term was discarcrded and new term, "osmotic demyelination syndrome (ODS)" is coined.

First, it's not an anatomic restriction process. Demyelination can be more diffuse and does not even necessarily involve the pons.

Second, and less well-known, not all patients with central pontine myelinolysis (CPM) have experienced a rapid increase in serum sodium!

The word 'syndrome' is added as it is an amalgam of many clinical signs and symptoms, though mostly neurological, such as

• Quadriparesis
• Dysarthria 
• Dysphagia
• Pseudobulbar Palsy*
• Gait instability
• Locked-in syndrome
• Delirium
• Coma

*marked by emotional lability, facial weakness, and uncontrolled crying or laughing

#electrolytes

#neurology

References:

1. Ayus JC, Wheeler JM, Arieff AI. Postoperative hyponatremic encephalopathy in menstruant women. Ann Intern Med 1992; 117:891.

2. Karp BI, Laureno R. Pontine and extrapontine myelinolysis: a neurologic disorder following rapid correction of hyponatremia. Medicine (Baltimore) 1993; 72:359.

3. Treves B, Consalvo F, Delogu G, Morena D, Padovano M, Santurro A, Scopetti M, Fineschi V. Osmotic demyelination syndrome: revisiting the diagnostic criteria through two fatal cases. BMC Neurol. 2024 Nov 5;24(1):428. doi: 10.1186/s12883-024-03934-3. PMID: 39497060; PMCID: PMC11536822.