[Etiology of water and electrolyte metabolism imbalance following the rupture of cerebral aneurysms--with special reference to preoperative condition].

One hundred fourteen patients with ruptured cerebral aneurysms were reviewed in regard to the incidence and etiological factors of preoperative disturbances of water and electrolyte metabolism. Patients with inadequate salt intake, evidence of renal disease, cardiac failure or excessive diuretic therapy were excluded. Twenty-five (21.9%) patients developed water and electrolyte disturbances. Hyponatremia (less than 130 mEq/l) occurred in 18 (15.8%) of 114 patients. The majority of those patients with hyponatremia showed laboratory findings and/or clinical features suggesting the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The mean interval between the last subarachnoid hemorrhage (SAH) and the development of hyponatremia was 13.5 days (range 6 to 26 days). No patients developed hypernatremia (more than 155 mEq/l). Preoperative diabetes insipidus (DI) occurred in 7 (6.1%) of 114 patients. The mean interval between the last SAH and the onset of DI was 26.5 days (range 15 to 35 days). When compared with the onset of hyponatremia following SAH, the development of DI was significantly delayed. The present study showed that the following five types of patients significantly related to the development of preoperative water and electrolyte disturbances after SAH due to cerebral aneurysms. The patients with ruptured aneurysms of anterior communicating, anterior cerebral artery or internal carotid artery. The patients in grade III, IV according to Hunt & Hess. The patients with high density in the basal subarachnoid space on the CT scan. The patients with a small hematoma in the region of the basal frontal interhemispheric fissure in cases with aneurysms of the anterior communicating or anterior cerebral artery.(ABSTRACT TRUNCATED AT 250 WORDS)