Central PontineMyelinolysis(CPM) is a largely irreversible, dreaded neurologic complication caused by osmotic demyelination, as a result of increasing sodium levels too rapidly. It is definitively diagnosed via Brain MRI.
Symptoms may include dysphagia, dysarthria, paraparesis,quadriparesis, lethargy, seizure, or even coma, and usually begin within 2 to 6 days following sodium elevation (i.e. may not be apparent in the emergency department).
If the hyponatremic patient is symptom-free, treat conservatively by restricting oral fluid intake to less than 1500 mL per day. Isotonic fluids (i.e. 0.9% normal saline) may be used, particularly if the patient is dehydrated.
If the hyponatremic patient is symptomatic, hypertonic saline (i.e. 3%, start with 100 mL bolus) may be used.
Increase sodium level by no more than 1.5 to 2 meq/L per hour for the first 3 to 4 hours until symptoms resolve. Increase by no more than 10 meq/L in the first 24 hours.
Take Home Point: Prevent devastation of CPM by treating asymptomatic hyponatremia conservatively and by closely monitoring rate of sodium increase.
