Diagnostic Value and Prognostic Value of the Blood Level Determination of S100 Protein in Minor or Mild Traumatic Brain Injury (GCS Glasgow Score 9 to 15).

Nearly two hundred thousand head injury cases (Traumatic Brain Injury - TBI) are reported each year in France. Less than 5% are severe, defined by a Glasgow score (GCS) above 9. Epidemiological studies indicate that TBI is the fourth leading cause of death and disability in industrialized countries. Major causes of mild/minor TBI are falls and domestic trauma in the elderly or children, and sports accidents. The minor/mild brai injury (MBI) may represent 5 to 10% of emergency consultations in the UAA.

The severity of a head injury is assessed by the Glasgow Coma Scale (GCS), and TBI are divided into three groups: minor (13-15), moderate (9-12) , severe (3-8). Definition of TCC has considerably evolved over the past 20 years, to take into account the pathophysiologic lesions secondary is related to systemic factors (hypotension, hypoxia ...) and intracranial factors ( intracranial hypertension, seizures committals ...). These side events, occurring within hours or days after the primary injury caused by an impact (contusion, hematoma, deceleration), increase the morbidity of the initial event, and must therefore be detected both early and fully.

The diagnosis of TBI requires imaging data such as craniocerebral tomography (CCT), which will be renewed after 24 hours and if necessary the following day. Until now, no pertinent biological marker was proposed to complete the clinical/imagery investigation of mild/moderate TBI.

S100B protein (S100) is a constitutive protein of glial cells, whose physiological functions are both intracellular, i.e. intracytosolic calcium binding, and extracellular, e.g. by promoting neuritic proliferation and/or neuronal apoptosis. Due to specificity of its cellular expression, S100B protein is a useful biological marker of acute neurological disorders, such as ischemic or haemorrhagic stroke, and traumatic head injury. hemorrhage, ischemic stroke) or traumatic (TCC). Plasma S100 is significantly increased in subjects with a major TCC, but also in the majority of minor or moderate TBI. A prognostic value of S100 also was suggested : patients who exhibited medical or social sequelae after several months after TBI also shoed high plasma levels of S100 in the first hours of the head injury. Such results of international clinical studies proposed S100 as a biomarker of diffuse brain injury, and indicate the importance of early determination of plasma concentration of S100 and its integration among the other elements of diagnosis (imaging) for assessing the severity of trauma and its short and long terms.

Medical objective of the study: