Sodium Balance and Symptomatic Vasospasm in Patients with Subarachnoid Hemorrhage

Hyponatremia is a common complication after subarachnoid hemorrhage. Although the mechanism of hyponatremia is still controversial, cerebral salt wasting syndrome is currently more favored over the the syndrome of inappropriate secretion of antidiuretic hormone. To accurately manage body water and electrolytes in the acute stage of subarachnoid hemorrhage, we prospectively studied the relations among the daily sodium balance, serum sodium, central venous pressure, and body weight. Ten of 30 patients demonstrated hyponatremia (serum sodium <135 mEq/L) during day 7 to 9 after subarachnoid hemorrhage. In these 10 patients hyponatremia was always preceded by a negative sodium balance, a decrease in central venous pressure and a decrease in body weight. Symptomatic vasospasm was coincident with hyponatremia in two patients. In 13 of the 20 patients who did not develop hyponatremia, we found a negative sodium balance; its duration was significantly shorter than with patients with hyponatremia. These findings indicate that natriuresis develops within the first week after subarachnoid hemorrhage: and when a negative sodium balance due to natriuresis lasts several days, hyponatremia with dehydration develops at the second week. These factors increase the risk of symptomatic vasospasm. We conclude that a greater replacement of water and sodium is required to maintain "normovolemia" within the first week after subarachnoid hemorrhage. This fluid replacement protocol may be helpful for the prevention of vasospasm following subarachnoid hemorrhage.