Poststenotic Distal Caliber Reduction Predicts Very High-Grade Proximal Internal Carotid Artery Stenosis.

BACKGROUND: Angiography relates the residual lumen to the poststenotic distal lumen (NASCET criterion) and expresses the result in percent lumen reduction. This method is not applicable when there is a collapse of the distal lumen, as seen in severe stenosis. The purpose of this study was to evaluate whether the reduced poststenotic caliber could be an additional sonographic criterion for estimation of the degree of stenosis. METHODS: We measured the caliber of the distal lumen of the extracranial internal carotid artery (ICA) in 57 patients with low-grade stenosis <50% (NASCET criterion), and in 57 patients with unilateral stenosis of ≥ 50 %. All were classified following international recommendations. The criteria used included the poststenotic velocity to discriminate moderate to high-grade stenosis (50-70%) from very high-grade (≥ 80 %) stenosis. In addition, we measured the interrater reliability of the ultrasonic measurement of the lumen in the distal ICA. RESULTS: In the group of patients with 50% to 70% stenosis, the distal lumen was 4.3 ± 0.6 mm. In the group with very high-grade stenosis ≥ 80%, the distal lumen was 2.6±0.5mm (p<0.0001). A distal lumen of 3.2 mm or less predicted a very high-grade stenosis with a sensitivity of 0.92 and a specificity of 0.96 (AUC 0.986; 95% CI 0.97-1.00; p=0.0001). CONCLUSION: The distal poststenotic lumen is an additional ultrasonic criterion to discriminate a very high-grade ICA stenosis from a lesser degree of ICA stenosis. It can help avoid misinterpretation due to the high variability of intrastenotic peak systolic velocities (PSV) in very high-grade ICA stenoses.

Grading carotid stenosis using ultrasonic methods.

The controversy as to whether Doppler ultrasonic methods should play a role in clinical decision-making in the prevention of stroke is attributable to reported disagreement between angiographic and ultrasonic results and the lack of internationally accepted ultrasound criteria for describing the degree of stenosis. Foremost among the explanations for both is the broad scatter of peak systolic velocities in the stenosis, the criterion that has so far received most attention. Grading based on a set of main and additional criteria can overcome diagnostic errors. Morphological measurements (B-mode images and color flow imaging) are the main criteria for low and moderate degrees of stenosis. Increased velocities in the stenosis indicate narrowing, but the appearance of collateral flow and decreased poststenotic flow velocity prove a high degree stenosis (≥70%), additionally allowing the estimation of the hemodynamic effect in the category of high-degree stenosis. Additional criteria refer to the effect of a stenosis on prestenotic flow (common carotid artery), the extent of poststenotic flow disturbances, and derived velocity criteria (diastolic peak velocity and the carotid ratio). This multiparametric approach is intended to increase the reliability and the standard of reporting of ultrasonic results for arteriosclerotic disease of the carotid artery.

Prognostic relevance of ultra-early doppler sonography in acute ischaemic stroke: a prospective multicentre study.

BACKGROUND: Ischaemic stroke can result from a temporary or permanent occlusion of intracranial arteries. In the hyperacute stage of the disease cerebrovascular ultrasound can be used to determine the vascular pathology, but the significance of very early findings on ultrasound is unclear. The present study aimed to assess the prognostic value of doppler ultrasonography within the first hours after stroke for functional outcome. METHODS: In a prospective multicentre design, patients with clinical signs of ischaemic anterior-circulation stroke were examined by doppler ultrasonography of the intracranial and extracranial arteries. Patients were separated into three groups according to the findings: normal middle-cerebral artery (MCA); branch occlusions; or a main-stem occlusion. The primary endpoint was functional outcome at 3 months. Logistic regression was used to test the association between the ultrasound diagnosis and functional outcome. RESULTS: 361 patients were identified with moderate to severe clinical deficits (National Institutes of Health Stroke Scale score 5-25). Of these, 121 (34%) had a normal MCA, 176 (48%) had branch occlusions, 7 (2%) had severe MCA stenosis, and 57 (16%) had a main-stem occlusion. 50 of the 57 (88%) patients with main-stem occlusion were dead or dependent 3 months after stroke. An occlusion of the main stem of the MCA within 6 h after stroke was an independent predictor for poor outcome (p=0.0006). 50% of patients with ultrasonographic diagnosis of branch occlusions and 63% with normal MCA had a good outcome. Combination of CT scan without early signs of infarction and a normal MCA resulted in a predictive value of 71% for a good functional outcome. INTERPRETATION: Cerebrovascular ultrasonography provides additional functional prognostic information in the hyperacute stage of ischaemic stroke. The technique is practical in a well-resourced unit, can be used to identify patients with high risk for poor functional outcome, and thus would be an appropriate investigation for future trials.

Design of a multicentre study on neurosonology in acute ischaemic stroke. A project of the neurosonology research group of the World Federation of Neurology.

This report summarises the design and organisation of a multicentre study on neurosonology in acute ischaemic stroke. The Neurosonology in Acute Ischaemic Stroke Study will determine whether extracranial and transcranial Doppler and duplex sonography performed within 6 h after onset of stroke improves prediction of functional outcome if applied in addition to routine diagnostic admission investigations, i.e. medical history, standardised neurological examination, brain imaging by computed or magnetic resonance tomography, electrocardiography, and baseline laboratory examination. The primary hypothesis is that there is a consistent and persuasive difference between patients with an occluded middle cerebral artery and those with an open artery in terms of the functional deficit after 3 months. Power calculations are based on the assumption of alpha=0.05 (two-sided test) and a probability of a maximally mild functional deficit of 0.4. Detection of a 20% difference with a power of 0.8 resulted in a calculated sample of 400 patients to be observed. Calculation took into consideration that only 50% of admitted patients would have a moderate to severe neurological deficit of whom only 30% will have an occlusion of the corresponding middle cerebral artery. Furthermore, the study is designed to evaluate a difference of the functional outcome in relation to occurrence and time of recanalisation in-patients presenting with an initially occluded middle cerebral artery.