Is ultrasound examination sufficient in the evaluation of patients with internal carotid artery severe stenosis or occlusion?

Background And Purpose: Carotid endarterectomy (CE) has been shown to be beneficial in patients with symptomatic high-grade internal carotid artery (ICA) stenosis. Some authors have suggested that when ultrasound shows a stenosis 70-99%, CE can be performed without further imaging study. However, ultrasound findings that suggest an ICA occlusion, not confirmed by angiography but which instead show a near-occlusion usually benefit from CE. The objectives of this study are: (1). to evaluate how angiography-obtained information on intracranial arteries affects the treatment decision in patients with 70-99% ICA stenosis, and (2). to evaluate when a symptomatic ICA occlusion shown by ultrasound could actually be a patent artery and therefore benefit from CE.

Materials And Methods: We prospectively collected the cerebral angiograms of 133 consecutive patients with TIA or non-disabling stroke due to large artery disease where ultrasound suggested a stenosis >or=70% or occlusion of symptomatic ICA; we calculated the frequency of intracranial vascular malformations and intracranial artery disease (IAD) located in the infraclinoid or supraclinoid portion of the ICA, and in the anterior or middle cerebral artery.

Results: Ultrasound showed 31 ICA occlusions and 102 ICA with 70-99% stenosis. All the patients with an ICA stenosis 70-99% on ultrasound examination had the degree of stenosis confirmed by angiography. Two out of 31 patients did not have a complete occlusion but angiography showed a near-occlusion and consequently they underwent CE. Sixty-five (62.5%) out of 104 patients with patent ICA had IAD (mild 26.9%, moderate 21.2%, and severe 14.4%). Five patients (4.8%) had intracranial vascular malformations (4 aneurysms and 1 arteriovenous malformation). One patient had disabling stroke during angiography. Seven patients (6.7%) did not undergo CE after angiography (1 patient had an aneurysm >10 mm, 1 patient had a very tight stenosis of the basilar artery, 5 patients had intracranial stenosis more severe than the extracranial stenosis).

Conclusions: In patients that on the basis of ultrasound examination can benefit from CE, information on intracranial arteries is necessary. Moreover, complete occlusion cannot be detected with certainty only by ultrasound examination.