Delayed Transcranial Echo-Contrast Bolus Arrival in Unilateral Internal Carotid Artery Stenosis and Occlusion

Some patients with internal carotid artery (ICA) occlusion or stenosis are at risk of developing a hemodynamic stroke. Transcranial ultrasonography using an echo-contrast bolus technique might be able to assess the extent of hemodynamic compromise. We describe a transcranial Doppler sonographic method that analyzes the differences in echo-contrast bolus arrival between both middle cerebral arteries after intravenous echo-contrast application. Ten patients with 50%-79% ICA stenosis, 10 patients with 80%-99% ICA stenosis and 22 patients with ICA occlusion were studied and compared with 15 age-matched controls. There were significant increases in delayed filling of the middle cerebral artery in both 80%-99% stenoses and occlusions compared with controls. The extent of the observed delays did not correlate with vasomotor reactivity. Echo-contrast bolus arrival time can be used to gain additional information on the intracranial hemodynamic effects of extracranial carotid artery disease that seems to be independent of the established ultrasound indices.