CNS Manifestations of Hyponatremia and Its Treatment

Hyponatremia is by far the commonest electrolyte disorder encountered in the clinical practice. The extracellular osmolarity is an important determinant of action potential conduction in neurons as well as glial cell volume. Neurological impairment is a widely recognised complication of hyponatremia and this occurs as a result of the failure of brain adaptative mechanisms to low serum osmolarity or abrupt osmotic changes. Because the brain is enclosed in a rigid skull, any changes in the brain volume induced by a decreased extracellular osmolarity could potentially result in severe symptoms like seizure or fatal brain herniation. On the other hand it has been established that rapid correction of hyponatremia is the principal risk factor for osmotic demyelination syndrome (ODS) which is a peculiar disorder characterised by loss of myelin in specific regions of the central nervous system.