[The syndrome of "inappropriate" antidiuretin secretion associated with a subarachnoid hemorrhage from a ruptured aneurysm].

In a patient with subarachnoid haemorrhage due to the rupture of an Arteria-communicans-anterior aneurysm, hyperadiuretinism developed which could be diagnosed by laboratory examinations. The pathological condition was removed by a reduction of the daily supply of liquids. The lesson that can be learned from this case is that in the treatment of patients with subarachnoid haemorrhages a systematic control of the serum sodium level, the sodium excretion an the osmolality of the serum and the urine is important.