Pontine and Extrapontine Myelinolysis: Risk Factors and Characterization of Patients Diagnosed in Three Decades in a Tertiary Center.

Background: Osmotic demyelination syndrome is a rare neurological disorder caused by damage to the myelin sheath of oligodendrocytes, typically due to a rapid increase in serum osmolarity. Objective: The objective of the study was to investigate the factors associated with the development of pontine or extrapontine myelinolysis. Methods: A retrospective, observational study which included patients with magnetic resonance imaging-confirmed diagnosis of pontine and extrapontine myelinolysis from 1990 to 2024 at a referral hospital in Mexico City. Results: Fourteen patients were included; the median age was 49 years, and 35.7% were men. Regarding comorbidities, diabetes was the most frequent (35.7%), followed by liver cirrhosis, malnutrition, and chronic alcoholism. Significantly, hyponatremia was found in 11 patients (78.5%), being severe in 42.8% of the patients. Other frequent biochemical abnormalities were hypokalemia (42.8%) and hypomagnesemia in 5 (35.7%). Sodium overcorrection occurred in 50% of patients, and the 90-day mortality rate was 28.5%. Conclusions: Electrolyte disturbances, particularly hyponatremia, were common in this population, along with the comorbidities traditionally associated with this condition. Although neurological sequelae and mortality have decreased over time, they remain present in 64% and 28.5% of patients, respectively. (Rev Invest Clin. 2025;77(1):1-5).