[Hyponatremia after subarachnoid hemorrhage caused by ruptured intracranial aneurysm]

Hyponatremia developed both prior to and after surgery in 30.5% and 23.4% out of 164 patients with ruptured intracranial aneurysms. It was more frequent postoperatively in those patients in whom baseline serum sodium levels were lower. Hyponatremic patients were older than normonatremic. The mean difference in age was about 7 years. The authors, basing on CT scans, have found that hyponatremia development has been more likely in patients with blood visible in subarachnoid space, specially chiasmatic cistern, and patients with ventricular bleeding or hydrocephalus. Hyponatremia following subarachnoid hemorrhage seems to result from the ischemic lesions to hypothalamus i may, therefore, be considered as vegetative equivalent of so-called cerebrovascular spasm.