Hypernatremia as the Initial Presentation of Osmotic Demyelination Syndrome: A Rare Case with Favorable Neurological Outcome.

INTRODUCTION: Osmotic demyelination syndrome (ODS) occurs due to rapid shifts in serum sodium levels and osmolality, resulting in neuronal damage. While it is most often caused by the rapid correction of chronic hyponatremia, other electrolyte imbalances have also been identified as potential triggers. Risk factors include alcohol abuse, malnutrition, and liver disease, among others, with common symptoms including tetraparesis, dysphagia, and altered consciousness. CASE PRESENTATION: We report the case of a 45-year-old male with alcohol dependence who presented to the emergency department with hypernatremia (154 mmol/L), altered mental status, and slurred speech. Despite gradual sodium correction, his condition deteriorated, and head MRI revealed findings consistent with central pontine myelinolysis and Wernicke's encephalopathy. After 5 months of hospitalization for severe ODS, including the need for a tracheostomy and gastrostomy, extensive rehabilitation enabled the patient to regain full independence in daily activities. CONCLUSION: This is a rare case of ODS presenting with hypernatremia in the setting of dehydration, malnutrition, and alcohol dependence. A preceding chronic osmotic adaptation, possibly related to unrecognized hyponatremia, may have contributed, although this could not be confirmed. Early detection, aided by MRI, was critical. Despite the severity of ODS, gradual correction of hypernatremia and extensive rehabilitation led to substantial recovery, highlighting the importance of long-term management and rehabilitation in improving patient outcomes.