Hyponatremia in neurosurgical patients.

Hyponatremia played an essential role in this case, determining the rapid transition from consciousness to a state of coma in female patient who had just come through the critical phase of intensive care. This circumstance underlines the importance of a correct water balance in patients undergoing neurosurgery, as well as a knowledge of the inappropriate antidiuretic hormone secretion (SIADH) syndrome responsible, either alone or in association, for the genesis of severe hyponatremia. In the differential diagnosis of hyponatremia, it is important to recall the role of an often mistaken syndrome (cerebral salt wasting syndrome) characterized by the secretion of a natriuretic factor that has still not been clearly identified.