Isolated extra pontine myelinolysis ? a rare imaging appearance of osmotic demyelination syndrome

Rapid correction of hyponatraemia leads to serious neurological complications, like osmotic demyelination syndrome(ODS). In ODS, magnetic resonance imaging (MRI) often reveals features of pontine myelinolysis, that may occur in isolation or may, sometimes be associated with extrapontine myelinolysis. Isolated extrapontine myelinolysis is rare. We report the case of a 53-year-old lady brought to the emergency service with vomitings, and altered sensorium. She was found to have profound hyponatraemia (serum sodium 110 meq/L). Correction of hyponatremia was done with slow intravenous infusion of 3% sodium chloride. However, inadvertant, concomitant oral administration of salt led to overcorrection with serum sodium going upto 150 meq/L. She developed quadriplegia, depressed level of consciousness and respiratory failure and required ventilatory support. MRI brain showed features of isolated extrapontine myelinolysis.