Osmotic Demyelination Syndrome – Evidence‑Based Overview

Definition & Pathophysiology

• Osmotic demyelination syndrome (ODS) is a rare but potentially devastating neurological complication characterized by non‑inflammatory demyelination of brain white‑matter tracts, most commonly affecting the central pons (central pontine myelinolysis), and is typically triggered by overly rapid correction of severe hyponatremia. 1

High‑Risk Populations

• Neurosurgical patients—especially those with subarachnoid hemorrhage or traumatic brain injury—are at increased risk for ODS. 1

Prevention Strategies

Sodium‑Correction Limits

• In patients with chronic hyponatremia, serum sodium should not be increased by more than 10 mmol/L per day to minimize the risk of ODS. 1

Evaluation Threshold

• Hyponatremia of ≤ 131 mmol/L warrants formal evaluation and treatment to prevent unsafe rapid correction. 3

Tailored Correction for High‑Risk Groups

• Slower correction rates are particularly crucial for patients with malnutrition, chronic alcoholism, liver disease, or concurrent electrolyte abnormalities (e.g., hypokalaemia, hypophosphataemia). 3

Fluid Management in Neurosurgical Patients

• In neurosurgical patients with subarachnoid hemorrhage, fluid restriction must be avoided; instead, volume replacement with isotonic or hypertonic saline is recommended even when hyponatremic, to prevent cerebral vasospasm and infarction. 3

Diagnostic Approach (Imaging)

• Magnetic resonance imaging (MRI) is the definitive diagnostic modality for ODS, revealing characteristic T2/FLAIR hyperintensity and T1 hypointensity in the central pons with peripheral sparing, often producing a “trident sign.” (Evidence cited in the primary source). 1

Management After Onset

• Once ODS develops, care is primarily supportive in an intensive‑care setting; no specific disease‑modifying therapy has strong evidence. (Supported by expert consensus). 1