Osmotic demyelination

  • Occurs if hyponatremia is rapidly corrected
  • This destroys blood-brain barrier, causes hypertonic fluid accumulation in extracellular space, causes non-inflammatory demyelination, affecting mainly pons
  • Paralysis, dysphagia, dysarthria, pseudobulbar palsy
  • Death frequent
  • MRI
    • High T2 signal in central pons, with symmetrical trident pattern sparing periphery and corticospinal tracts
    • Hypointense on T1
    • Peripheral contrast enhancement
    • Restricted diffusivity
    • If patient survives, chronic lesions appear as a cavitation
    • Extrapontine sites of involvement: cerebellum and lateral genicular body, less common in thalamus, subcortical white matter and basal ganglia
Read more

Howard, Stephanie A., et al. “Osmotic demyelination syndrome.” Radiographics 29.3 (2009): 933-938.

Alleman, Anthony M. “Osmotic demyelination syndrome: central pontine myelinolysis and extrapontine myelinolysis.” Seminars in Ultrasound, CT and MRI. Vol. 35. No. 2. WB Saunders, 2014.