RESUMEN
Salt-losing encefalopathy is a controversial clinical manifestation initially described by Peters in 1950 and reconsidered by Nelson in 1981. It is characterized by an excessive renal loss of sodium and water during an intracraneal disease, secondary to proximal tubular reabsorption dysfunction. Clínical manifestations include severe polyuria, hyponatremia, hypouricemia and hypovolemia. It is important to differentiate this disease from other polyric manifestations, specially with the Syndrome of Inappropriate ADH Secretion (SIADH), since its treatment is the complete contrary and consists of replacing large quantities of salt, and isotomic solutions. The inability to recognize this manifestation may lead to incorrect treatment, to serious deterioration of the neurological condition (associated to cerebral aneurisms), and to an increase in mortality. We present 4 neurosurgical cases (operated cerebral aneurisms) that accorded with this syndrome and were treated as such. The complete clinical history, differential diagnosis and physiopathology are discussed in detail, and literature is revised