Predictive Value of Mean Flow Velocity by TCD in Early Cerebral Vasospasm in Aneurysmal Subarachnoid Hemorrhage

Cerebral vasospasm is defined as narrowing of a cerebral blood vessel enough to cause reduction in distal blood flow. Seventy percent of aSAH patients develop angiographic vasospasm but only 30% progress to develop evident neurological deficits. Cerebral vasospasm may be asymptomatic with no clinical symptoms and signs but only abnormal investigations, such as vascular stenosis by angiography or high blood flow speed by Doppler ultrasound.

Standard tests used to determine the source of bleeding and diagnose cerebral vasospasm (CV) include neuroimaging studies that administer contrast either intravenously (computed tomography angiography [CTA]) or intra-arterially (digital subtraction angiography [DSA]). Cerebral blood flow measurements using computed tomography (CT) perfusion techniques may detect the degree of cerebral ischemia in a very early stage. Although well-tolerated, these studies cannot be readily performed on the bedside and expose the patient to additional radiation, thus significantly restricting their use in daily cerebral hemodynamics monitoring. Moreover, they involve patient transportation to the CT scanner and utilization of resources such as nurses, technologists, and ancillary personnel.

Early detection of cerebral vasospasm is an important step in the way of the improvement of the outcome and the survival of aSAH patients. Transcranial duplex (TCD) is a non-invasive modality which can assess the cerebral blood vessels diameters and flow velocities that can be a useful maneuver in early detection of vasospasm after aSAH