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.