[CO2 test with transcranial Doppler sonography in cerebral ischemia]

We evaluated the CO2-induced vasomotor reactivity of the cerebral vasculature in 48 patients with high degree stenosis or occlusion of the internal carotid artery by transcranial Doppler ultrasonography measuring changes of flow velocities in the middle cerebral artery. Further, the vasomotor reactivity of the basilar artery was measured in 48 patients with vertebro-basilar ischemia. These results were compared with the findings in normal individuals. The vasomotor reactivity was significantly reduced in patients with stenosis or occlusion of the internal carotid artery as compared to normal controls. In patients with high degree ICA stenoses, undergoing to carotid surgery, CO2-test showed a significant improvement of the pathological vasomotor reactivity 6 month after the operation. In the group of patients with vertebro-basilar ischemia, the vasomotor reactivity measured in the basilar artery, was significantly reduced in patients with completed brainstem infarctions but not in patients with transient brainstem ischemia or infarctions in the posterior cerebral artery territory. We conclude that evaluation of the cerebral vasomotor reactivity by transcranial Doppler ultrasound is able to identify an inadequate cerebral blood supply and may help to estimate the hemodynamic effect of stenosis or occlusion of the extracranial brain supplying arteries.