Increased urinary sodium excretion in the early phase of aneurysmal subarachnoid hemorrhage as a predictor of cerebral salt wasting syndrome

Cerebral salt wasting syndrome (CSWS) in patients with aneurysmal subarachnoid hemorrhage (SAH) is considered to correlate with delayed ischemic neurological deficits (DIND) induced by cerebral vasospasm; however, its exact mechanism is still not well-known. The purpose of the present study is to evaluate the relationship between hyponatremia caused by CSWS and the increase of the urinary sodium excretion in early phase following SAH. Fifty-four patients with SAH were divided into 2 groups, normonatremia group and hyponatremia group which suffered hyponatremia after SAH. The hyponatremia group comprise 14 patients (26%) in whom the hyponatremia developed of the SAH. In this group, the serum level of sodium significantly decreased 7 days after SAH and then gradually normalised. Further, excretion of sodium in the urine tended to increase 3 days after SAH and significantly increased 7 days after SAH. In conclusion, the increased urinary sodium excretion in the early phase of SAH would serve as a predictive factor for CSWS after SAH. We consider that it is important to start sodium and fluid supplementation and inhibit natriuresis by fludrocortisone acetate administration before hyponatremia occurs in order to prevention delayed ischemic neurological deficits in SAH patients.