Comparative analysis of plasma and salivary S100B as predictors of traumatic brain injury severity according to GCS and MAIS/head.

Background: Accurate assessment of traumatic brain injury (TBI) severity is essential for clinical management and outcome prediction. Traditional tools, like the Glasgow Coma Scale (GCS) and Maximum Abbreviated Injury Scale for head injuries (MAIS/Head), have limitations, particularly in cases involving sedation, complex injuries, or diffuse brain injuries. This study evaluates the diagnostic accuracy of plasma and salivary S100B levels as biomarkers for TBI severity, based on GCS and MAIS/Head, with emphasis on emergency settings.

Methods: Multicenter prospective cohort study enrolled 57 adult patients with blunt TBI. TBI severity was assessed using GCS and MAIS/Head. Plasma and salivary S100B samples were collected 2-4h post-injury and measured via ELISA. Receiver operating characteristic (ROC) curves assessed S100B's discriminative capacity for TBI severity.

Results: Plasma and salivary S100B concentrations were higher in moderate and severe TBI cases. ROC analysis revealed strong discriminative performance for plasma (AUC = 0.87 and 0.83) and salivary S100B (AUC = 0.85 and 0.83), for GCS and MAIS/HEAD, respectively. Salivary S100B showed 100 % specificity for mild TBI and 100 % sensitivity for moderate TBI (MAIS/Head). Plasma S100B exhibited 100 % sensitivity for severe TBI (GCS ≤8). Both biomarkers did not distinguish between moderate and severe injuries.

Conclusions: Plasma and salivary S100B levels effectively discriminate mild from severe TBI, complementing current clinical severity scales. Their use may support rapid decision-making in emergency departments, especially given the simplicity, non-invasiveness, and feasibility of salivary sampling. These findings support integrating S100B measurement into TBI management protocols to enhance clinical accuracy and patient outcomes.