Circulating inflammatory markers may predict the broad clinical spectrum of traumatic brain injury (TBI). The present study aimed to illustrate the role of leukocytes, precisely neutrophil and lymphocytes, in neuroinflammation as a new vista in neuro-critical care. Search terms were: elevations in peripheral blood leukocytes counts, neutrophil, lymphocyte with precisely neutrophil to lymphocyte ratios, associated with adverse outcomes of traumatic brain injury, pre and post-operative conditions of intracerebral haemorrhage, seizures, delirium, non-convulsive status epilepticus, confusion, aphasia, agitation, coma, disability and death. As a result, we identified 16 publications describing leukocyte biomarkers associated with neuroinflammation following TBI from PubMed, Cochrane Registry of Controlled Trials, Medline and Embase (Ovid) on randomised controlled trials (RCTs), non-RCTs and cohort studies published in the last decade. This study concluded that elevations in peripheral blood leukocyte and neutrophil to lymphocyte ratios could predict adverse outcomes of a cerebral haemorrhage.