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

Lingxin Cai,Xinyan Wu,Cong Qian,Xiaoxiao Tan,Hanhai Zeng,Gao Chen

doi:10.3389/fneur.2021.671098

Lingxin Cai, Xinyan Wu + Show 4 more

Open Access

https://doi.org/10.3389/fneur.2021.671098

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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.

Highlights

Aneurysmal subarachnoid hemorrhage is the leading cause of death in stroke patients, with a mortality rate of ∼40–50% [1, 2]
The dynamics of inflammatory cells and cytokines in the periphery can contribute to systemic inflammatory response syndrome (SIRS) [8] and immunosuppression [9], which can perhaps increase the risk of infection [10]
Inflammation disrupts the balance between endogenous vasodilators and vasoconstrictors, especially the Abbreviations: aSAH, aneurysmal subarachnoid hemorrhage; neutrophil-to-lymphocyte ratio (NLR), neutrophilto-lymphocyte ratio; EBI, early brain injury; DCI, delayed cerebral ischemia; BBB, blood–brain barrier; SIRS, systemic inflammatory response syndrome; CSF, cerebrospinal fluid; CNS, central nervous system; TLR4, toll-like receptor 4; IL6, interleukin-6; IL-1β, interleukin-1β; TNF-α, tumor necrosis factor-alpha; NO, nitric oxide; CAMs, cell adhesion molecules; MMP-9, matrix metalloproteinase-9; PSGL-1, P-selectin glycoprotein ligand-1; MPO, myeloperoxidase; mRS, Modified Rankin Scale; ANS, autonomic nervous system; SNS, sympathetic nervous system; HPA, hypothalamic–pituitary–adrenal

Summary

INTRODUCTION

Aneurysmal subarachnoid hemorrhage (aSAH) is the leading cause of death in stroke patients, with a mortality rate of ∼40–50% [1, 2]. Inflammation disrupts the balance between endogenous vasodilators and vasoconstrictors, especially the Abbreviations: aSAH, aneurysmal subarachnoid hemorrhage; NLR, neutrophilto-lymphocyte ratio; EBI, early brain injury; DCI, delayed cerebral ischemia; BBB, blood–brain barrier; SIRS, systemic inflammatory response syndrome; CSF, cerebrospinal fluid; CNS, central nervous system; TLR4, toll-like receptor 4; IL6, interleukin-6; IL-1β, interleukin-1β; TNF-α, tumor necrosis factor-alpha; NO, nitric oxide; CAMs, cell adhesion molecules; MMP-9, matrix metalloproteinase-9; PSGL-1, P-selectin glycoprotein ligand-1; MPO, myeloperoxidase; mRS, Modified Rankin Scale; ANS, autonomic nervous system; SNS, sympathetic nervous system; HPA, hypothalamic–pituitary–adrenal. Wu et al found that the NLR may be a practical index to predict the occurrence of DCI in aSAH patients They studied 122 patients, and 43 of them developed DCI during hospitalization and had an increased white blood cell count, neutrophil count, and NLR and a lower lymphocyte count. Univariate analysis showed that the NLR in patients with rebleeding was significantly higher than that in patients without rebleeding

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