Invasive Versus Non Invasive Measurement of Intracranial Pressure in Brain Injury Trial (IMPRESSIT)

Inclusion Criteria: * Brain injury (All patients with brain injury, at risk of developing intracranial hypertension, requiring invasive intracranial pressure monitoring. ); * Patients requiring invasive ICP monitoring; * Age \> 18 yrs. Exclusion Criteria: * inaccessible ultrasound window; * a cardiovascular disease causing hemodynamic variations affecting the TCD reading (severe arrhythmia, severe cardiac valvular stenosis, moderate or severe vasospasm), * Patient already with craniotomy or craniectomy before first time frame 1°, * any treatment for intracranial hypertension or manipulation of arterial blood pressure intervening between the non-invasive ICPtcd measurements and the invasive ICP (ICPi) measurement.