Utility of S-100B As a Potential Tool for Neuromonitoring and Prediction of Neuroworsening in Acute Phase of Traumatic Brain Injury

Aim: In this review, we summarize the evidence on the use of S-100B in traumatic brain injury (TBI) of all severities, its clinical significance, and its prognostic value in the different posttrauma phases. Background: Most of the published studies report the serum determination of S-100B in the context of mild TBI as a predictor of positive CT scan, which represents a valuable tool when establishing a criterion to indicate the performance of the CT and decide the medical discharge. Likewise, we have reported several studies that correlate S-100B with the clinical evolution of the patient with severe TBI, showing an excellent indicator of intracranial hypertension. However, there are few studies that report on the impact of S-100B as a predictor of neuroworsening in the acute phase in moderate TBI. Review results: Traumatic brain injury comprises a heterogeneous group of traumatic injuries that can evolve progressively. Almost 90% of head injuries that reach the hospital are mild head injuries or mild TBI, which is defined by a score of more than 12 on the Glasgow Coma Scale (GCS). Of this, a few can be accompanied by a hemorrhagic lesion that can be detected by further imaging techniques. Still, utilizing these techniques in every single patient that comes to the ER does not only take a toll on the finances of the hospital but, more importantly, also exposes the patients to unnecessary radiation. There are still difficulties to correlate the findings on imaging with secondary injury, and to predict the clinical evolution in the acute phase and in the long-term. Serum S-100B levels have shown high sensibility and negative predictive value (NPV) for intracranial complications after mild head injury. Most of the published studies report that measurement in serum of S-100B in the context of mild TBI, as a predictor of CT findings, represents a valuable tool when establishing a criterion for indication of CT and to decide medical discharge. However, there are few studies that report the impact of S-100B as a predictor of neuroworsening in the acute phase of moderate TBI, which is defined by a score between 9 and 12 on the GCS. Conclusion: Serum S-100B is a useful marker of brain damage in TBI. Its usefulness has been studied mainly as a support to evaluate the need to perform a CT scan in mild TBI, and to monitor patients with moderate-to-severe TBI, in order to predict the outcome and validate the response to treatment. This review highlights S-100B as a versatile marker whose clinical utility depends on the severity of the head trauma. In this way, S-100B would be a potential predictor of neuroworsening in the acute phase in moderate TBI. Clinical significance: Despite its valuable utility as a predictor of positive CT in mild TBI, and as a tool for neuromonitoring in established severe TBI, the greater utility of S-100B could be as a predictor of neuroworsening in the acute phase in the moderate TBI.