Spiral computed tomography: a novel diagnostic approach for investigation of the extracranial cerebral arteries and its complementary role in duplex ultrasonography.

BACKGROUND: For the detection of atherosclerotic lesions of the extracranial cerebral arteries, duplex ultrasonography (US) is an established operator-dependent method, whereas arteriography is associated with the not-insignificant risk of embolic complications. Spiral CT is a promising novel diagnostic tool that allows noninvasive, operator-independent diagnosis of obstruction of extracranial cerebral arteries. The aim of our prospective study was to evaluate in a clinical setting the complementary role of duplex US and spiral CT. METHODS AND RESULTS: We compared the results obtained independently by spiral CT and duplex US in 59 consecutive patients with clinical suspicion of an obstructive lesion affecting the carotid arteries. We analyzed a total of 354 segments from the extracranial carotid arteries, including the common, internal, and external carotid arteries. A total of 4 complete occlusions, 38 severe stenoses (70% to 99%), and 32 moderate stenoses (30% to 69%) were concordantly identified by means of duplex US and spiral CT. In 5 cases in which duplex US did not allow sufficient evaluation of the carotid artery because of a poor US window or severe calcification, spiral CT allowed identification and correct measurement of the stenotic lesion. The comparison of the percentage of stenosis with both methods was good (r=0.91, P=0.024). CONCLUSIONS: Our results indicate that spiral CT of the extracranial cerebral arteries is a promising noninvasive complementary and non-operator-dependent examination. Its application is particularly attractive in cases in which duplex US is not reliable (ie, severe kinking, severe calcification, short neck, and high bifurcation) and particularly when an overall view of the vascular field is required.

Isolated complete orbital infarction: a common carotid artery occlusion syndrome.

When blood flow through the internal and external carotid arteries is completely interrupted by ipsilateral common carotid artery occlusion, the arterial orbital circulation may be more compromised than the brain supply. We studied a pure and extreme example of this situation in a patient who presented with acute orbital infarction, but no cerebral ischemia on clinical, CT and single-photon emission computerized tomography (SPECT) grounds. Ipsilateral blindness corresponded to retinal, choroidal and optic nerve infarction. The pattern of ophthalmoplegia, with relative sparing of adduction, was more compatible with a muscle than a nerve dysfunction, but a reactive dilated pupil, corneal anesthesia, and orbital pain suggested that the intraorbital branches of the ocular motor nerves and ophthalmic division of the trigeminal nerve were not spared. In addition, signs of widespread ocular ischemia were present. Sequential examinations documented the evolution pattern over 1 year. The absence of an orbital collateral supply from the contralateral external carotid and muscular cervical arteries systems, which contrasted with an adequate middle cerebral artery supply via the contralateral internal carotid artery, may explain this isolated and complete form of orbital ischemia due to common carotid artery occlusion.