Association Between Postoperative Interleukin-6 Levels in Cerebrospinal Fluid and Invasiveness of Surgery for Subarachnoid Hemorrhage

Background: Interleukin (IL)-6 levels in cerebrospinal fluid (CSF) may reflect postoperative inflammation and affect the outcomes of aneurysmal subarachnoid hemorrhage (SAH). Methods: This study retrospectively analyzed CSF IL-6 levels on the first postoperative day in 77 patients with SAH treated by craniotomy or endovascular coiling within 12 h of diagnosis. IL-6 levels were measured by enzyme-linked immunosorbent assay and compared between treatment groups. Associations with cerebral vasospasm and clinical outcomes were evaluated by multiple regression analysis. Results: The median IL-6 level in CSF was 10,501 pg/mL [interquartile range 3,037.8, 43,118.5] and was significantly lower in the endovascular group than in the craniotomy group (p < 0.001). In the craniotomy group, the IL-6 level was higher in patients with involvement of the anterior communicating artery than in those with aneurysm at other sites (p = 0.008). Cerebral vasospasm was identified in 13.0% of cases and was associated with elevated IL-6 (p = 0.003). Higher IL-6 levels were correlated with unfavorable outcomes (p < 0.05). Conclusion: Elevated IL-6 levels in CSF on postoperative day 1 were associated with cerebral vasospasm and worse outcomes in patients with SAH. Endovascular treatment resulted in lower IL-6 levels, suggesting that minimally invasive methods may reduce inflammation and improve the prognosis. Regulating IL-6 could be a potential therapeutic strategy in SAH management.