Accuracy of the S100β protein as a marker of brain damage in traumatic brain injury

Introduction: This study tested the hypothesis that S100 beta is a useful screening tool for detecting intracranial lesion (IL) in patients with a normal level of consciousness after traumatic brain injury (TBI). Methods: One hundred and forty-three post-TBI patients without a decrease in consciousness (GCS = 15) and with at least one neurological symptom (e.g. transitory loss of consciousness, amnesia, headache, dizziness or vomiting) were prospectively included. A blood sample was drawn at 6-hours post-TBI. A routine CT scan was obtained within 24 hours post-injury. Diagnostic properties of S100 beta for IL prediction in CT scan findings were tested using ROC-analysis. Results: A total of 15 patients (10.5%) had IL. Serum levels were significantly higher in these patients. Significant differences were found between S100 beta levels and CT scan findings (p = 0.007). ROC-analysis showed that S100 beta is a useful tool for detecting the presence of IL in CT scans (p = 0.007). In this series, the best cut-off for S100 beta is 0.130 mu g L(-1), with 100% sensitivity and 32.81% specificity. Conclusion: Within the first 6 hours post-TBI, serum S100 beta seems to be an effective biochemical indicator of IL in patients without a decrease in consciousness. These results indicate that higher S100 beta cut-off values substantially improve the clinical relevance of this protein.