Decreased serum sodium levels predict symptomatic vasospasm in patients with subarachnoid hemorrhage

Background: Symptomatic vasospasm is a major cause of morbidity and mortality in subarachnoid hemorrhage patients. Hyponatremia and dehydration due to natriuresis after subarachnoid hemorrhage are related to symptomatic vasospasm. Therefore, most institutions are currently targeting euvolemia and eunatremia in subarachnoid hemorrhage patients to avoid complications. We retrospectively investigated the predictors of symptomatic vasospasm with respect to water and sodium homeostasis, while maintaining euvolemia and eunatremia after subarachnoid hemorrhage. Methods: We monitored changes in serum sodium levels, serum osmolarity, daily sodium intake, daily urine volume, and daily water balance for 14 days after subarachnoid hemorrhage. Outcomes were assessed using the modified Rankin scale at 1 month after subarachnoid hemorrhage. Results: Among 97 patients, 27 (27.8%) had symptomatic vasospasm. Patients with symptomatic vasospasm were older than those without symptomatic vasospasm; the occurrence of symptomatic vasospasm affected outcomes. Serum sodium levels were sequentially significantly decreased, but within the normal range from 1 day before the occurrence of symptomatic vasospasm. Serum osmolarity of the spasm group was lower than that of the non-spasm group. Conclusions: Symptomatic vasospasm occurs more often in older patients and affects outcomes. A decrease in serum sodium levels occurs a day before symptomatic vasospasm. This observation may help predict symptomatic vasospasm.