Transcranial color-coded duplex sonography in unilateral flow-restrictive extracranial carotid artery disease

PURPOSE: To provide transcranial color-coded duplex flow-velocity data for the basal cerebral arteries in patients with unilateral flow-restrictive extracranial carotid artery disease, and to compare these data with the flow velocities obtained in healthy control subjects. METHODS: Transcranial color-coded duplex sonography was performed in 78 patients with different patterns of cross flow through the anterior and posterior communicating arteries associated with unilateral obstruction (70% to 100%; 46 stenoses and 32 occlusions) of the internal carotid arteries. Peak systolic, mean, and end diastolic velocities were measured in the anterior, middle, and precommunicating and postcommunicating posterior cerebral arteries. These measurements were compared with the values obtained in 125 age- and sex-matched healthy control subjects. RESULTS: Patients with anterior communicating artery cross flow to the middle cerebral artery (63%) had increased peak velocity in the anterior cerebral artery and decreased peak velocity in the middle cerebral artery on the obstructed (ipsilateral) side, and increased peak velocity in the anterior cerebral artery on the unobstructed (contralateral) side. Patients with anterior communicating artery cross flow to the pericallosal artery (19%) had increased contralateral peak systolic velocity and mean anterior cerebral artery velocities. Patients without anterior communicating artery cross flow (18%) had normal peak velocities in the anterior and middle cerebral arteries. Patients with posterior communicating artery cross flow (42%) had ipsilaterally decreased peak systolic and mean middle cerebral artery velocities and increased peak velocities in the precommunicating posterior cerebral artery. Patients without posterior communicating artery cross flow (58%) had ipsilaterally decreased peak systolic and mean middle cerebral artery velocities. CONCLUSION: Our findings suggest that typical abnormalities of basal cerebral artery flow velocities occur in patients with unilateral 70% to 100% obstruction of the internal carotid arteries resulting in different patterns of cross flow through the circle of Willis.