Patients with mild to moderate traumatic brain injury (TBI) are at risk for secondary neurological deterioration. Their outcome within the first week after injury could be predicted by clinical signs, brain CT scan and transcranial doppler (TCD) on admission to the emergency room. The investigators aim to evaluate the diagnostic performance of TCD to screen patients presented with mild to moderate TBI and mild lesions on CT scan, i.e., Trauma Coma Data Bank, TCDB classification II. The principal outcome measure is the negative predictive value of TCD.

Criteria for inclusion:

• 15 years of age or more
• primary admission for mild TBI (GCS 14-15) or moderate (GCS 9-13) TBI.
• with or without multiple injury.
• with no hemodynamic or respiratory distress: SAP >90mmHg, SPO2 >92%,hemoglobin > 8 g/dl.
• with mild brain lesions on CTscan according to the traumatic coma data bank classification (TCDB) II: diffuse injury with cisterns present and no midline shift, mixed density lesions <25 ml.
• Transcranial Doppler within 8 hours after the trauma.
• patient affiliated to the social security system or equivalent

Criteria for exclusion:

• Severe TBI (GCS<9)
• Penetrating TBI
• patient with no brain CT scan
• patient with normal brain CT scan (TCDB I), or severe brain CT scan (TCDB III-IV)
• Hemodynamic or respiratory distress
• Patient treated with anticoagulants: oral anticoagulant, heparin, anti-platelet agent (except Aspirin)
• previous intracranial surgery
• Patient with sedation and mechanical ventilation
• transcranial Doppler unable
• patient deprived of freedom by judicial or administrative decision
• Follow up at 7 days impossible
• Refusal consent to use data for statistics

Primary admission of patients following mild to moderate traumatic brain injury who need exploration with brain CT scan.