Hyponatremia is associated with malignant brain edema after mechanical thrombectomy in acute ischemic stroke

Hyponatremia (< 135 mmol/L) is the most common electrolyte disturbance in patients with stroke. However, few studies have reported the relationship between hyponatremia at admission and outcomes in patients with acute ischemic stroke (AIS) treated with mechanical thrombectomy (MT). This study is aimed to explore the association between hyponatremia and clinical outcomes following MT.

A retrospective study was conducted at our center. The primary outcome was postoperative malignant brain edema (MBE). The secondary outcomes included mortality and adverse function at the 90-day follow-up, which were defined as modified Rankin scale scores of 6 and > 2, respectively. Patients were classified into hyponatremia and nonhyponatremia groups based on their serum sodium concentration at admission before drug use. The occurrence of MBE was evaluated via computed tomography after MT, and 90-day outcomes were obtained through in-person interviews at the clinic or via telephone. Multivariate analysis was performed to investigate the associations among postoperative MBE, 90-day mortality, adverse function and hyponatremia.

A total of 342 patients were enrolled into the study, of whom 52 (15.2%) had hyponatremia, 86 (25.1%) developed postoperative MBE, 93 (27.2%) died within 90 days after MT, and 201 (58.8%) had adverse functions at the 90-day follow-up. Multivariate analysis revealed that hyponatremia was significantly associated with postoperative MBE (odds ratio [OR] 3.91, 95% confidence interval [CI] 1.66 - 9.23, p = 0.002), 90-day mortality (OR 5.49, 95% CI 2.48 - 12.14, p < 0.001), and 90-day adverse function (OR 3.25, 95% CI 1.29 - 8.12, p = 0.012). In addition, mediation analysis revealed that postoperative MBE may partially account for the 90-day mortality/adverse function of patients with hyponatremia (regression coefficients changed by 18.6% and 23.9%, respectively).

Hyponatremia is an independent predictor of postoperative MBE, 90-day mortality, and adverse function. Correction of hyponatremia may reduce the postoperative MBE to improve the prognosis of patients.