The investigators hypothesize that patients with mild TBI and normal TCD can be safely discharged home immediately after the ED. The targeted population is the category of patients eligible for early discharge: 1) patients with mild lesions on the initial CT scan and a GCS 15 after CT scan completion and, 2) patients with no lesion on the initial cerebral CT scan with at least one of the following risk factors: GCS 14 after CT scan completion, persisting post-traumatic nausea/vomiting/headaches, concomitant alcoholic intoxication or patients treated with aspirin. The study will not include mild TBI patients who are not eligible for early discharge: patients with no possibility of home supervision, those with a GCS lower than 14 after the CT scan or those treated with anticoagulant/antiplatelet drugs other than aspirin. The investigators expect the TCD-based strategy to be non-inferior compared to the standard strategy according to French recommendations in terms of the 3-months neurological outcome. From a public health standpoint, the use of TCD as a triage tool may change current guidelines regarding mild TBI management.

Patients with mild traumatic brain injury (TBI) represent the vast majority of TBI patients admitted in the emergency department (ED). According to French recommendations, mild TBI patients with brain lesions on initial CT scan are directed to a standard ward, where neurologic monitoring consists of repeated CT scanning and clinical exams. Patients with no lesion on initial cerebral CT scan are also hospitalized 1) when their GCS after CT scan is lower than 15, 2) in case of persisting nausea, vomiting or headache, 3) in case of concomitant alcoholic intoxication and, 4) in case of on-going treatment with aspirin. This strategy induces significant hospital stay with potential morbidity, whereas neurologic worsening rarely occurs.

In this context, the implementation of a triage tool in the ED would be useful to screen patients at risk of early neurologic worsening. Hence, low risk patients may be discharged at home immediately after the ED. Transcranial Doppler (TCD) is a non-invasive technique that measures cerebral blood flow velocities in intracranial cerebral arteries. These velocities and a derivated parameter (pulsatility index, PI), estimate cerebral blood flow (CBF) and have become a standard of care to optimize CBF in after severe TBI. Only few studies report the use of TCD after mild TBI. In a single-center cohort of patients with mild-to-moderate TBI, TCD parameters measured at hospital admission accurately predicted early neurologic worsening. These encouraging results indicate that TCD, in combination with CT scan findings, could play a role in the management of patients with mild TBI.

The aim of this project is to determine whether a TCD-based strategy is non-inferior to the standard management in terms of the overall neurological outcome at 3 months after mild TBI with no/minor lesions detected on a cerebral CT scan.

Inclusion Criteria:

• Mild TBI (GCS 13-15 on ED admission) with one of the following:

• Patient with minor cerebral lesion on initial CT scan (TCDBII i.e. no midline shift, visible basal cisterns and haemorrhagic lesion < 25 cc) and GCS 15 after CT scan

• OR * Patient with normal initial CT scan (TCDB I) with at least one risk factor :

  • GCS = 14 after CT scan
  • and/or alcoholic intoxication
  • and/or on-going treatment with anticoagulants or anti-platelet therapy
  • and /or persisting nausea, and/or vomiting and/or headaches
  • Early initial CT scan (< 4 hours after TBI)

• Possibility of home supervision by a third-party

• Affiliation to the French social security system

• Patient have signed consent form

• Possibility to perform a TCD within 12 hours

• Stable hemodynamics defined as a blood pressure greater than 90 mmHg, an SpO2 greater than 92% and a hemoglobin concentration greater than 8g/dl, or, in the absence of measured physiologic parameters or the absence of biological sampling, mention in the patient's medical record of a stable clinical examination in terms of hemodynamics and respiratory function.

Exclusion Criteria:

• CT scan classified as TCDB III - VI
• Penetrating head-trauma
• Patient under mechanical ventilation
• Patients treated with anticoagulants or anti-platelet therapy (except Aspirin)
• Hospitalization required by post-traumatic extra-cranial lesion, intoxication (except alcoholic), pre-existing condition (including congenital hemostasis disorders) or social factors at the discretion of the physician.
• Internal Carotid dissection
• Post-traumatic lesion in the posterior cerebral fossa
• Subject in exclusion period of another interventional study,
• Pregnant women, breastfeeding women
• Subject under administrative or judicial control, under protection

The evaluation at 3 months after TBI will be centralized by the coordinating centre and blinded.