Hyponatremia and cerebral infarction in patients with ruptured intracranial aneurysms: is fluid restriction harmful?

We studied retrospectively the relationship between hyponatremia and cerebral infarction in 134 consecutive patients with aneurysmal subarachnoid hemorrhage. In 44 patients sodium levels fell below 135 mmol/L on at least two consecutive days between the second and the tenth day after the hemorrhage. Twenty-five of these patients fulfilled the criteria for the syndrome of inappropriate secretion of antidiuretic hormone. Cerebral infarction developed in 27 of the 44 patients with hyponatremia and in 19 of the 90 patients with normal serum sodium levels (p less than 0.001). Cerebral infarctions were more often fatal in patients with hyponatremia (p less than 0.01). Twenty-six of the 44 patients had been treated with fluid restriction to correct the serum sodium levels, and infarctions developed in 21. Fluid restriction to correct hyponatremia appears to be potentially dangerous in patients with aneurysmal subarachnoid hemorrhage.