Correlation of Routine Admission Inflammatory Biomarkers with Individual Traumatic Brain Lesion Types in Mild Traumatic Brain Injury

Background: Routine admission inflammatory and metabolic biomarkers have been proposed as adjunctive tools in mild traumatic brain injury (mTBI). However, their association with specific traumatic intracranial lesion types remains unclear. Methods: We conducted a prospective observational study including adult patients with isolated mTBI who underwent head computed tomography (CT) on admission. Admission laboratory parameters included the platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and glucose-to-potassium ratio (GPR). Two predefined endpoints were assessed. The first compared biomarker values between CT-positive and CT-negative patients. The second evaluated associations between biomarkers and individual intracranial lesion subtypes, including analyses restricted to isolated lesions. Results: A total of 125 patients were included, of whom 95 (76%) were CT-positive. No significant differences were observed between CT-positive and CT-negative patients for PLR (p = 0.793), GPR (p = 0.531), or SII (p = 0.291). In lesion-specific analyses including all intracranial injuries, subdural hematoma (SDH) was associated with higher GPR compared with patients without SDH (p = 0.016). In analyses restricted to patients with isolated lesions, SDH was associated with higher PLR (p = 0.018) and higher GPR (p = 0.015). No significant associations were observed between any biomarker and intraparenchymal hemorrhage, subarachnoid hemorrhage, or epidural hematoma (all p > 0.05). Patients with multiple intracranial injuries exhibited higher PLR (p = 0.012) and higher SII (p = 0.021) compared with those with isolated lesions. After correction for multiple comparisons, none of the observed associations remained statistically significant. Conclusions: These findings suggest that routine systemic biomarkers have limited global discriminatory value in mTBI. Exploratory lesion-specific associations with SDH did not remain significant after correction for multiple comparisons, underscoring the preliminary nature of these findings.