Hyponatremia is associated with cerebral ischemia in patients with aneurysmal subarachnoid hemorrhage.

The association between hyponatremia and cerebral ischemia was investigated in a consecutive series of 208 patients with subarachnoid hemorrhage who had a daily fluid intake of at least 3 L and in whom fluid restriction, to correct hyponatremia, was not applied. Hyponatremia occurred in 70 (34%) of the 208 patients. The occurrence of cerebral ischemia in patients with hyponatremia, 17 (24%) of 70 patients, was significantly higher than in patients without hyponatremia, 17 (12%) of 138 patients (chi 2 = 4.028, p = 0.045). Cerebral ischemia was not more often fatal in hyponatremic patients than in patients without hyponatremia. We conclude that patients with hyponatremia are at increased risk of developing cerebral ischemia even if fluid restriction is not applied.