Inclusion Criteria- Age 18 or more years old
- Patients with an acute stroke corresponding to anterior circulation, a CT scan ruling out intracranial hemorrhage, presenting within 12 hours from symptom onset
- NIHSS ≥1
- Susceptible to be tilted down to the flat position or to 30º of the head
- There is uncertainty about the benefit/harm of head position during a minimum of 24 hours.
- Informed consent given
Exclusion Criteria- Contraindications to a flat head position (active vomiting, pneumonia, uncontrolled heart failure)
- Concomitant medical illness that would interfere with outcome assessment and follow-up
- Planned decompressive craniectomy or carotid endarterectomy.
- Absence of sonographic temporal window