Is Salivary S100B a Biomarker of Traumatic Brain Injury? A Pilot Study

Abstract

Traumatic brain injury (TBI) results in short and long-term disability neurodegeneration. Mild traumatic brain injury (mTBI) represents up to 85% of head injuries; diagnosis and early management is based on computed tomography (CT) or in-hospital observation, which are time-and cost-intensive. CT involves exposure to potentially harmful ionizing radiation and >90% of the scans are negative. Blood-brain barrier (BBB) damage is suspected pathological event post-TBI contributing to long-term sequelae and a reliable and rapid point-of-care test to screen those who can safely forego acute head CT would be of great help in evaluating patients with an acute mTBI. In this pilot study, 15 adult patients with suspected TBI (mean age = 47 years, range 18-79) and 15 control subjects (mean age = 33 years, range 23-53) were enrolled. We found that the average salivary S100B level was 3.9 fold higher than blood S100B, regardless of the presence of pathology. [S100B] saliva positively correlated with [S100B] serum (Pearson' coefficient = 0.79; p < 0.01). Salivary S100B levels were as effective in differentiating TBI patients from control subjects as serum levels (Control vs. TBI: p < 0.01; Serum ROC AUC = 0.94 and Saliva ROC AUC = 0.75). I These initial results suggest that measuring salivary S100B could represent an alternative to serum S100B in the diagnosis of TBI. Larger and confirmatory trials are needed to define salivary biomarker kinetics in relation to TBI severity and the possible roles of gender, ethnicity and age in influencing salivary S100B levels.

Peripheral Blood and Salivary Biomarkers of Blood–Brain Barrier Permeability and Neuronal Damage: Clinical and Applied Concepts

“…In another pilot study, 15 adult patients with suspected TBI and 15 control subjects were studied. Average salivary S100B level was 3.9-fold higher than blood S100B level, regardless of the presence of pathology [S100B] saliva correlated positively with [S100B] serum , and salivary S100B levels were as effective in differentiating TBI patients from control subjects as serum levels ( 172 ).…”

Blood biomarkers for mild traumatic brain injury: a selective review of unresolved issues

“…Analytic issues such as test-retest reliability, test sensitivity, inconsistencies across test platforms, and issues related to storage and handling of samples have not been addressed in this work (for a discussion of some of these issues see [13]. We focused on blood levels of biomarkers and did not address biomarker levels in the cerebrospinal fluid, urine, or saliva [130,131]. Evidence from the clinical setting and from animal models indicates a disruption of the blood brain barrier occurs after moderate to severe traumatic brain injury [132][133][134][135][136][136][137][138][139] and that biomarkers can cross the blood brain barrier into the blood [11,62].…”

Does acute soccer heading cause an increase in plasma S100B? A randomized controlled trial

“…Nonetheless, it is important that practitioners pair S100B with additional objective methods, such as neuroimaging or other blood biomarkers (e.g., neurofilament light [NF-L], tau, glial fibrillary acidic protein [GFAP]) [ 70 ], in addition to subjective symptom reporting from the patient. Furthermore, emerging data on salivary-based S100B, which has shown to adequately differentiate concussion patients from controls (AUC = 0.74) [ 71 ], may have a direct implication to clinical practice in near future. Nonetheless, multimodal validation of biomarker findings is needed.…”