The Role of the Blood Neutrophil-to-Lymphocyte Ratio in Aneurysmal Subarachnoid Hemorrhage

Abstract

Aneurysmal subarachnoid hemorrhage (aSAH) is an important type of stroke with the highest rates of mortality and disability. Recent evidence indicates that neuroinflammation plays a critical role in both early brain injury and delayed neural deterioration after aSAH, contributing to unfavorable outcomes. The neutrophil-to-lymphocyte ratio (NLR) is a peripheral biomarker that conveys information about the inflammatory burden in terms of both innate and adaptive immunity. This review summarizes relevant studies that associate the NLR with aSAH to evaluate whether the NLR can predict outcomes and serve as an effective biomarker for clinical management. We found that increased NLR is valuable in predicting the clinical outcome of aSAH patients and is related to the risk of complications such as delayed cerebral ischemia (DCI) or rebleeding. Combined with other indicators, the NLR provides improved accuracy for predicting prognosis to stratify patients into different risk categories. The underlying pathophysiology is highlighted to identify new potential targets for neuroprotection and to develop novel therapeutic strategies.

Clinical Value of Inflammatory Cytokines in Patients with Aneurysmal Subarachnoid Hemorrhage

“…However, when baseline data were compared between patients with good and poor prognoses, it was discovered that patients with poor prognoses had higher WFNS grade and MFS, more extensive aneurysms, and the same variability in leukocytes, neutrophils, lymphocytes, and glucose. Corroborating findings were reported in a previous study, 40 where factors, such as the severity of disease and bleeding volume could affect the prognosis of aSAH patients. Additionally, this previous study indicated the same differences in the levels of inflammatory cytokines between patients with severe and mild aSAH.…”

Admission Serum Iron as an Independent Risk Factor for Postoperative Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage: A Propensity-Matched Analysis

“…Systemic inflammatory response syndrome is common [ 37 ] and is considered a fundamental factor that increases susceptibility to DCI after aSAH [ 38 , 39 ]. Numerous inflammatory biomarkers, including C-reactive protein (CRP) [ 40 ], neutrophil to lymphocyte ratio (NLR) [ 25 , 41 ], white blood cell count (WBC) [ 40 ], interleukin-6 (IL-6) [ 42 ], and tumor necrosis factor-α (TNF-α), were presented at elevated levels in plasma following aSAH, and were related to the development of DCI [ 38 , 39 , 43 ].…”

Routine laboratory parameters, including complete blood count, predict COVID-19 in-hospital mortality in geriatric patients

“…In COVID-19 patients, neutrophilia associated with lymphopenia was observed in patients with increased disease severity and with poor prognosis ( Picchi et al, 2021 , Yang et al, 2020 , Zhu et al, 2021 ). A number of studies showed a correlation between markers derived from standard blood count tests, such as neutrophil-to-lymphocyte ratio (NLR), derived NLR ratio (dNLR, neutrophil count divided by the result of WBC count minus neutrophil count), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) and systematic inflammatory response in a number of age-related diseases, including cancer ( Xu et al, 2021 , Ying et al, 2014 ), type 2 diabetes mellitus (T2DM) ( Tong et al, 2004 ), cardiovascular diseases (CVD) ( Bhat et al, 2013 , Ji et al, 2021 ), and stroke ( Cai et al, 2021a ).…”