Patency of external and internal carotid artery in the presence of an occluded common carotid artery: noninvasive evaluation with combined cerebrovascular Doppler examination and sequential computertomography.

The patency of the external carotid artery (ECA) and internal carotid artery (ICA) in the presence of an occlusion of the common carotid artery (CCA) was evaluated in 7 patients with a symptomatic CCA occlusion by the combined application of cerebrovascular Doppler examination (cv-Doppler) based on continuous-wave equipment and sequential computertomographic scans with intravenous bolus injection of contrast material (sequential CT-scans). Occlusion of the CCA was demonstrated by cv- Doppler and sequential CT-scans and confirmed by routine angiography. A patent ECA was found in all 7 patients by the combined method, but could not be demonstrated by routine angiography in one of these patients. A patent ICA was found in 2 patients by the combined method, while routine angiographic findings concerning the patency of the ICA were equivocal. An occluded ICA was found in 5 patients by the cv-Doppler-sequential CT-scans method, where routine angiographic findings also were equivocal. Operation to restore blood flow in the CCA was performed in 5 patients and successful in 3 patients in whom blood flow from the CCA to the ECA could be achieved in 2 patients, and to the ECA and ICA in one patient, as predicted by the combined cv-Doppler-sequential CT-scans method. Thus, the patency of the ICA in the presence of a CCA occlusion can be reliably evaluated by the combined diagnostic procedure. The method may help to decide for further diagnostic work-up, e.g., specific selective injections and projections in more than two plans during cerebral angiography, and/or successful surgical intervention in a given patient with a CCA occlusion, even if angiographic findings are equivocal.