Introduction: Extrapontine myelinolysis associated with metabolic abnormalities especially hypernatremia is extremely rare. Osmotic demyelination syndrome resulting from postpartum hypernatremia is recently described entity with hypernatremic encephalopathy, quadriparesis and rhabdomyolysis with myelinolysis on imaging. This communication aims to highlight a case and discuss the pathogensis and management. Case Report: A 20 year-old lady presented with fever and disorientation of 5 days and generalized seizures of 1-day. She had undergone a lower segment caesarean section following an uneventful antenatal period, 3 weeks prior to this and was discharged home on 7th postoperative day where she was keeping well for next 1 week. On examination she was febrile, vitals stable, drowsy, flexing limbs and opening eyes to pain, with no verbal response. Limbs were flaccid; deep tendon and bilateral plantar reflexes were unresponsive. Biochemical evaluation revealed a sodium level of 182meq/l, creatinine phosphokinase (CPK) -2207 U/L, urea-135mg/dl, and creatinine-4.3mg/dl. Neuroimaging showed T2/FLAIR hyperintensities in bilateral putamen, isthmus of hippocampus, middle cerebellar peduncles, posterior internal capsule, and subcortical white matter suggestive of extrapontine myelinoysis. Inspite of correction of metabolic abnormalities, she progressively worsened and succumbed to her illness in 7 days. Conclusion: Clinicians must be aware of this entity of postpartum hypernatremia secondary to water restriction and diabetes insipidus and treat at the earliest, as mortality remains high (>60%). 

Keywords: Hypernatremia; Myelinolysis; Postpartum; Osmotic; Diabetes Insipidus.