Central pontine myelinolysis and poorly controlled diabetes: MRI’s hints for pathogenesis

Dear Sir, Central pontine myelinolysis (CPM) is usually associated with a rapid correction of hyponatremia [1, 2]. In a patient with chronic hyponatremia, oligodendrocytes in the pons decrease their inner osmolarity to protect them from swelling. Thereafter, any rapid osmotic shift in the opposite direction caused by the hypertonic fluid can induce the swollen cells to shrink, leading to osmotic demyelination [1, 2]. Typical MRI features in CPM are characterized by cytotoxic edema (DWI hyperintensity and ADC hypointensity) consistent with shrinkage of the pontine cells [3]. We describe a case of CPM due to poorly controlled diabetes with brain MRI features compatible with vasogenic edema (DWI and ADC hyperintensity) that may suggest an extracellular space expansion rather than shrinkage of the pontine cells