Hyponatremia is a very common electrolyte disorder, especially in the elderly, and is associated with significant morbidity, mortality and disability. In particular, the consequences of acute hyponatremia on the brain may be severe, including permanent disability and death. Also chronic hyponatremia can affect the health status, causing attention deficit, gait instability, increased risk of falls and fractures, and osteoporosis. Furthermore, an overly rapid correction of hyponatremia can be associated with irreversible brain damage, which may be the result of the osmotic demyelination syndrome. This review analyzes the detrimental consequences of acute and chronic hyponatremia and its inappropriate correction on the brain and the underlying physiopathological mechanisms, with a particular attention to the less known in vivo and in vitro effects of chronic hyponatremia.
Keywords: brain; hyponatremia; hyponatremic encephalopathy; osmotic demyelination syndrome.