Neutrophil-to-lymphocyte Ratio and Platelet-to-lymphocyte Ratio as an Inflammatory Biomarker in Predicting the Severity of Secondary Brain Injury: A Review Article

Traumatic brain injury (TBI) is one of the leading causes of death and disability, which affects millions of people globally with a significant economic burden. The inflammatory reactions and immune system activity play a significant role in the severity development of secondary brain injury (SBI) after a TBI event. Neutrophils, platelets, and lymphocytes are involved in these inflammatory reactions and have potential in reflecting the severity level of SBI that occurred post-TBI. Some recent studies have shown that the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) can be used as a potential biomarker for determining the severity of an inflammatory reaction, including SBIs in post-TBI. However, the results of NLR and PLR in TBI patients in daily medical practice are still not fully utilized. This review summarizes the neutrophil’s, platelet’s, and lymphocyte’s role in SBI, also the NLR and PLR potential as a marker of the severity of the SBI process in TBI cases.