Osmotic demyelination syndrome
Background
- Formerly called "central pontine myelinolysis"
- A neurologic condition caused by rapid correction of hyponatremia, with starting serum sodium normally 120 meq/L or less
- Caused by rapid correction of hyponatremia (>12 mEq/L/24 h), as water moves from cells to extracellular fluid, yielding intracellular dehydration.
- Symptoms are often irreversible or only partially reversible
Risk Factors
- Chronic heart failure
- Alcoholism
- Cirrhosis
- Hypokalemia
- Malnutrition
- Treatment with vasopressin antagonists (e.g. tolvaptan)
Clinical Features
Symptoms can be present 2-6 days after rapid correction of serum sodium
- Dysarthria
- Dysphagia
- Lethargy
- Behavioral disturbances/ confusion
- Paraparesis or quadriparesis
- Seizures
- "Locked in" syndrome
- Coma and death
Differential Diagnosis
Evaluation
- MRI can be used to visualize the pontine lesion, with a characteristic "batwing" lesion of the pons appearing in typical cases
Management
In patients with chronic severe hyponatremia (Na <120mEq), the correction rate of sodium should not exceed 6 mEq/24 hours for patients with other ODS risk factors, or 12 mEq/24 hours for those without other risk factors (1). Hypertonic (3%) saline should be given at a low infusion rate, 0.5 to 1 mL/kg/h, with frequent serum sodium checks to ensure that the correction rate does not exceed the above limits.
Disposition
- Admit