Neurochemistry of hyponatremic encephalopathy evaluated by MR spectroscopy

MR spectroscopy in a patient with hyponatremic encephalopathy due to the syndrome of inappropriate secretion of antidiuretic hormone revealed decreased N-acetyl-aspartate, creatine plus phosphocreatine, choline-containing compounds, and myo-inositol, with normal glutamate and increased glutamine, which normalized after Na normalization. The decreased concentrations of creatine plus phosphocreatine, choline-containing compounds and myo-inositol are explained by their release as osmolytes from brain cells to adapt to hypo-osmolality induced cerebral edema. Increased glutamine, which not only acts as an osmolyte but also protects neu-rons under excitotoxic conditions, may suggest that a disrupted glutamate-glutamine cycle may play an important role in the patho-genesis of hyponatremic encephalopathy. (c) 2020 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.