Early Detection of Cerebral Vasospasm Following Aneurysmal Subarachnoid Hemorrhage by IL-6 Electrochemiluminescence Analysis of the Cerebrospinal Fluid

Background/objectives: Aneurysmal subarachnoid hemorrhage (aSAH) is a neurosurgical emergency associated with cerebral vasospasm, representing an important complication. This study assessed the association between cerebrospinal fluid (CSF) interleukin-6 (IL-6) levels and cerebral vasospasm after aSAH. Methods: This prospective single-center observational study with repeated measurements included 56 patients among 74 screened patients with aSAH; 18 patients were excluded according to predefined exclusion criteria, including infection, unavailable CSF samples or requirement for CSF diversion within the first seven days of onset. The samples were obtained via lumbar puncture on post-hemorrhage days 3 and 7. IL-6 was quantified using an electrochemiluminescent immunoassay. Radiological vasospasm (RV) was assessed by computed tomography angiography, while clinical vasospasm (CCV) was defined as new neurological deterioration unexplained by other causes. Results: Median IL-6 levels were 423.5 pg/mL on day 3 and 726.0 pg/mL on day 7. Day 7 IL-6 levels were associated with RV (p = 0.045) and CCV (p = 0.010), while day 3 IL-6 was associated with CCV only (p = 0.035). Day 7 IL-6 showed modest discriminatory performance for CCV: AUC = 0.722, cut-off 460 pg/mL, sensitivity 75.0%, and specificity 68.8%; for RV: AUC = 0.659, cut-off 451 pg/mL, sensitivity 81.8%, and specificity 56.5%. Conclusions: Elevated CSF IL-6 levels were associated with cerebral vasospasm after aSAH, with a more consistent association observed for CCV than for RV; however, these findings are hypothesis-generating and require validation before clinical applicability can be determined.