From the Guidelines
Osmotic demyelination syndrome is a serious neurological disorder that can occur when sodium levels in the body are corrected too rapidly, particularly in the treatment of hyponatremia, and it is crucial to correct sodium levels slowly to prevent this condition. This condition primarily affects the pons area of the brainstem, known as central pontine myelinolysis, but can also impact other brain regions, referred to as extrapontine myelinolysis 1. The symptoms of osmotic demyelination syndrome typically develop 2-6 days after rapid sodium correction and may include difficulty speaking or swallowing, behavioral changes, confusion, weakness or paralysis, movement disorders, seizures, and in severe cases, coma or death.
Prevention and Treatment
Prevention of osmotic demyelination syndrome is crucial and involves correcting sodium levels slowly, generally not exceeding 8-10 mEq/L in 24 hours and 18 mEq/L in 48 hours, as rapid correction can lead to this condition 1. Treatment is mainly supportive as there is no specific cure, focusing on managing symptoms and preventing further neurological damage. The condition occurs because rapid changes in serum sodium cause brain cells to lose water too quickly, triggering an inflammatory response that damages myelin. Some patients recover completely, while others may have permanent neurological deficits.
Key Considerations
It is essential to monitor serum sodium levels closely during the treatment of hyponatremia, especially when using medications like vaptans, which can cause a rapid increase in serum sodium concentration, and thus increase the risk of osmotic demyelination syndrome 1. The use of vaptans should be started in the hospital with close clinical monitoring to avoid increases of serum sodium of more than 8-10 mmol/L/day. Additionally, vaptans should not be given to patients in an altered mental state who cannot drink appropriate amounts of fluid because of the risk of dehydration and hypernatremia.
Recent Evidence
Recent studies have highlighted the importance of careful management of sodium levels to prevent osmotic demyelination syndrome, and the use of medications like vaptans has been shown to be effective in improving serum sodium concentration in patients with hypervolemic hyponatremia, but with a need for careful monitoring to avoid rapid correction 1. Other studies have also demonstrated the safety of hypertonic saline in critical care, without evidence of osmotic demyelination syndrome, when used appropriately 1.
From the Research
Definition and Causes of Osmotic Demyelination Syndrome
- Osmotic demyelination syndrome (ODS) is a serious neurological condition that occurs due to rapid changes in serum osmolarity, often as a result of the overly rapid correction of hyponatremia 2, 3, 4.
- It encompasses central pontine myelinolysis and extrapontine myelinolysis, characterized by neurological involvement related to the pons, brainstem, or other areas of the brain 3, 5.
- The exact etiology of ODS remains incompletely understood, despite growing evidence 3.
Risk Factors and Prevention
- Severe hyponatremia, hypokalemia, and rapid correction of these imbalances are significant risk factors for developing ODS 2, 3, 4.
- A more cautious and thoughtful correction of electrolyte alterations can prevent the onset of ODS 2.
- Physicians should be aware of the potentially fatal consequences of an exceedingly rapid change in serum osmolarity and strictly follow known safety measures to prevent it 2, 4.
Diagnosis and Treatment
- Diagnosing ODS requires a high index of suspicion, and early diagnosis is crucial for effective management 5.
- The treatment of ODS is primarily supportive, and most patients may show dramatic recovery 5.
- Immunomodulatory treatments, such as intravenous steroids and immunoglobulin, have been used in some cases, with reported improvements in patient outcomes 6.
- Plasmapheresis has also been used, with favorable outcomes reported in some cases, although more evidence is required to support its use in ODS 6.
Clinical Presentation and Outcomes
- ODS can present with a range of neurological symptoms, including altered sensorium, seizures, spastic quadriparesis, and lower cranial nerve palsy 3, 5.
- The condition can be fatal, with high mortality rates reported in some cases 3, 4.
- However, with prompt and appropriate treatment, some patients can experience significant improvement or even full recovery 2, 5, 6.