[Massive natriuresis and polyuria after triple craniocervical subarachnoid hemorrhage: cerebral salt wasting syndrome?].

A thirty-year-old male patient suffered subarachnoidal haemorrhage from an angioma positioned in the cranio-cervical transition. After rebleeding twice the patient developed a hydrocephalus internus malresorptivus and excessive natriuresis and polyuria, accompanied by depressed renin activity and extremely low aldosterone plasma levels. Neither fluid restriction and sodium substitution, nor administration of hydro-chlorothiazide/indomethacin affected natriuresis and polyuria. It was only after treatment with fludrocortisone-acetate/hydrocortisone that hyponatraemia and polyuria were resolved. At the same time a ventriculo-peritoneal shunt was applied. Differential diagnosis excluded the syndromes of inadequate antidiuretic hormone secretion, renal and cerebral diabetes insipidus, osmotic receptor hypofunction, chronic renal dysfunction and tubular necrosis. Natriuresis and polyuria developed under dexamethasone therapy. Since patient history, physical examination and laboratory criteria could not explain the electrolyte and fluid imbalance, this might be attributed to the hydrocephalus. Similar disturbances have been reported from other patients with intracranial disorders. Mechanical pressure exercised on the hypothalamus might cause the disturbance of fluid and sodium balance. Assuming a cerebral salt wasting syndrome, a putative natriuretic factor coming from the brain or an imbalance in the cerebral renin-angiotensin-system, as described in rats and dogs, must be discussed.