Cerebral salt-wasting syndrome (CSWS), also written cerebral salt wasting syndrome, is a rare endocrine condition featuring a low blood sodium concentration and dehydration in response to injury (trauma) or the presence of tumors in or surrounding the brain. In this condition, the kidney is functioning normally but excreting excessive sodium. The condition was initially described in 1950. Its cause and management remain controversial. In the current literature across several fields, including neurology, neurosurgery, nephrology, and critical care medicine, there is controversy over whether CSWS is a distinct condition, or a special form of syndrome of inappropriate antidiuretic hormone secretion (SIADH).