Delayed cerebral vasospasm (DCVS), early brain injury (EBI), and delayed cerebral ischemia (DCI) are devastating complications after aneurysmal subarachnoid hemorrhage (SAH). Interleukin (IL)-6 seems to be an important interleukin in the inflammatory response after SAH, and many studies describe a strong correlation between IL-6 and worse outcome. The aim of this study was to systematically review preclinical and clinical studies that evaluated systemic and cerebral IL-6 levels after SAH and their relation to DCVS, neuronal cell death, and DCI. We conducted two systematic literature searches using PubMed to identify preclinical and clinical studies evaluating the role of IL-6 after SAH. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 61 and 30 preclinical and clinical articles, respectively, were included in the systematic reviews. Of the preclinical studies in which IL-6 was measured in cerebrospinal fluid (CSF), parenchyma, and systemically, 100%, 94.4%, and 81.3%, respectively, showed increased expression of IL-6 after SAH. Preclinical results were mirrored by clinical findings in which elevated levels of IL-6 in CSF and plasma were found after SAH, correlating with DCVS, DCI, and worse outcome. Only two preclinical studies analyzed the direct inhibition of IL-6, which resulted in reduced DCVS and neuronal cell death. IL-6 is a marker of intracranial inflammation and plays a role in the pathophysiology of DCVS and DCI after SAH in preclinical animal models and clinical studies. Its inhibition might have therapeutic potential to improve the outcome of SAH patients.

迟发性脑血管痉挛 (DCVS)、早期脑损伤 (EBI) 和迟发性脑缺血 (DCI) 是动脉瘤性蛛网膜下腔出血 (SAH) 后的毁灭性并发症。白细胞介素 (IL)-6 似乎是 SAH 后炎症反应中重要的白细胞介素，许多研究描述了 IL-6 与更坏结果之间的强相关性。本研究的目的是系统评价评估 SAH 后全身和脑 IL-6 水平及其与 DCVS、神经元细胞死亡和 DCI 的关系的临床前和临床研究。我们使用 PubMed 进行了两次系统文献检索，以确定评估 SAH 后 IL-6 作用的临床前和临床研究。根据系统评价和元分析指南的首选报告项目，根据预定义的资格标准选择合适的文章。系统评价分别包括 61 篇和 30 篇临床前和临床文章。在脑脊液 (CSF)、脑实质和全身检测 IL-6 的临床前研究中，分别有 100%、94.4% 和 81.3% 的患者显示 SAH 后 IL-6 的表达增加。临床前结果反映在临床发现中，其中在 SAH 后发现脑脊液和血浆中 IL-6 水平升高，与 DCVS、DCI 和更差的结果相关。只有两项临床前研究分析了 IL-6 的直接抑制作用，这导致 DCVS 和神经元细胞死亡减少。IL-6 是颅内炎症的标志物，在临床前动物模型和临床研究中 SAH 后 DCVS 和 DCI 的病理生理学中发挥作用。它的抑制可能具有改善 SAH 患者预后的治疗潜力。