The significance of cerebral infarction and atrophy in patients with amaurosis fugax and transient ischemic attacks in relation to internal carotid artery stenosis: A preliminary report

Extracranial carotid stenosis: evidence based review

Extracranial cerebrovascular disease is one of the most important causes of death and disability worldwide and its treatment is based on clinical and surgical strategies, the latter being performed by conventional or endovascular techniques. The management of stenosis of the carotid bifurcation is mainly aimed at preventing stroke and has been the subject of extensive investigation. The role of clinical treatment has been re-emphasized, but carotid endarterectomy remains the first-line treatment for symptomatic patients with 50% to 99% stenosis and for asymptomatic patients with 60% to 99% stenosis. Stent angioplasty is reserved for symptomatic patients with stenosis of 50% to 99% and at high risk for open surgery due to anatomical or clinical reasons. Currently, the endovascular procedure is not recommended for asymptomatic patients who are able to undergo conventional surgical treatment. Brazil presents a trend similar to that of other countries in North America and Europe, keeping endarterectomy as the main indication for the treatment of carotid stenosis and reserving the endovascular procedure for cases in which there are contraindications for the first intervention. However, we must improve our results by reducing complications, notably the overall mortality rate.

High Agatston Calcium Score of Intracranial Carotid Artery: A Significant Risk Factor for Cognitive Impairment

The effect of intracranial internal carotid artery (ICA) calcification on cognitive impairment is uncertain. Our objective was to investigate whether intracranial ICA calcification is a significant cognitive predictor for cognitive impairment. Global cognition and degrees of intracranial ICA calcification of 579 subjects were assessed with Mini-Mental State Examination (MMSE) and Agatston calcium scoring method, respectively. Other risk factors for cognitive impairment, including age, education level, hypertension, diabetes mellitus, smoking, hyperlipidemia, and body mass index, were documented and analyzed for their associations with cognitive function. In univariate analyses, older age, lower education level, hypertension, diabetes mellitus, and higher intracranial ICA Agatston scores were significantly associated with cognitive impairment. In ordinal logistic regression, only age and total intracranial ICA Agatston score were significant risk factors for cognitive impairment. After adjustment for the other documented risk factors, subjects were 7% (95% CI: 5-10; P < 0.001) and 6% (95% CI: 0-13; P = 0.04) more likely to have lower cognitive category with every year increment of age and every 100-point increment of the total intracranial ICA Agatston score respectively. These results suggest an important role of the intracranial ICA calcification on cognitive impairment.

Basal Cerebral Computed Tomography as Diagnostic Tool to Improve Patient Selection in Asymptomatic Carotid Artery Stenosis

One-hundred patients were included to evaluate the role of cerebral computed tomography (CT) to improve patient selection in asymptomatic internal carotid stenosis. Symptomatic patients were assigned to group A, asymptomatic patients to group B. A cerebral CT pattern A was observed in groups A and B in 60% and 20%, respectively ( P < .0001). Between A and B groups, type 6 plaques were found, respectively, in 26.7% and 7.5% of patients ( P = .01); a type 5 in 51.7% and 45% ( P = .32) of patients; and a type 4 in 21.7% and 47.5% of patients, respectively ( P = .006). Within B group, the association of CT pattern A and histological plaque level 4, 5, and 6 was, respectively, 25% ( P = .15), 50% ( P = .53), and 25% ( P = .16). In group B, a 7-fold risk increase in CT pattern A was found in patients with level 6 plaque. In asymptomatic patients with high-risk plaque, a basal cerebral CT scan can be used as diagnostic tool to improve patient selection for intervention.

Screening for Significant Carotid Artery Disease among a Cohort of 1,000 Egyptian Patients

The objective of this study was to determine the prevalence of significant carotid artery disease (SCAD) in a cohort of Egyptian patients to compare it with matched groups of patients in published data of Western populations. One thousand consecutive patients referred for color flow duplex scanning of the carotid arteries were included. SCAD was defined as carotid stenosis ≥ 50% or occlusion. There were 567 males (56.7%), and the mean age was 60.4 years. There were 382 (38.2%) patients presenting with and 617 (61.7%) patients without specific carotid territory symptoms. SCAD was significantly more prevalent in patients aged ≥ 60 (13.2%, vs 6.25%; p < .001), in symptomatic patients (16.45% vs 6.32%; p < .001), in diabetics (15.96% vs 7.39%; p < .001), in patients with ischemic heart disease (17.65% vs 7.22%; p < .001), in hypertensive patients (12% vs 7.54%; p = .025), and in patients with dyslipidemia (12.53% vs 6.56%; p < .025). The prevalence of SCAD in this cohort of Egyptian patients was similar to that of matched patients of Western populations. Screening for SCAD in patients with specific carotid territory symptoms is recommended. Screening of asymptomatic subjects could be considered if they are ≥ 60 years of age and have three or more associated risk factors.

Chronic ischemia and neurocognition

Cognitive impairment from a major stroke as a consequence of carotid disease is an acknowledged clinical outcome; however, cognitive impairment without major stroke is open to discussion. The three recognized mechanisms for cognitive dysfunction from internal carotid artery are microembolization, white-matter disease, and hypoperfusion. The last has been most difficult to characterize physiologically. In this article, the authors review evidence supporting the existence of chronic ischemia in the brain and its direct impact on cognitive functions. By incorporating the pathophysiology of chronic ischemia into the algorithm of the management of carotid artery disease, we may be able to extend the goals of carotid artery revascularization beyond merely preventing stroke to include preventing or reversing cognitive decline.

Cerebral blood flow measurement by color velocity imaging in radiation-induced carotid stenosis

OBJECTIVE

To show whether there is any association between the development of neurologic symptoms and the total cerebral blood flow volume documented by color velocity imaging in patients with carotid stenosis that develops after radiotherapy.

METHODS

Twenty-three patients with nasopharyngeal carcinoma (4 female and 19 male; age range, 39-69 years; mean age, 55.6 years) and major extracranial carotid stenosis underwent color velocity imaging. In this group, 8 patients had symptoms of a stroke or transient ischemic attack, and the other 15 patients were asymptomatic. The color velocity imaging results in the symptomatic group were then compared with those in the asymptomatic group.

RESULTS

The cerebral blood flow in the symptomatic group was significantly lower than that in the asymptomatic group (224.1 +/- 89.0 versus 532.5 +/- 89.0 mL/min; P = .001).

CONCLUSIONS

Cerebral blood flow as measured by color velocity imaging was lower in the symptomatic group. There is an association between the development of neurologic symptoms and blood flow volume.

Patterns of brain computed tomography infarction and carotid plaque echogenicity

PURPOSE

It was suggested that in the absence of cardioembolism the discrete subcortical and cortical infarctions on brain computed tomography (CT) are most likely associated with carotid atheroma, whereas the hemodynamic infarctions, diffuse widespread white matter lesions, lacunae and basal ganglia infarctions are most likely associated with other pathologic conditions. The aim of this study was to determine the ultrasonic characteristics of carotid plaques and the degree of stenosis that were associated with the different brain CT infarction patterns and normal CT (pattern A, discrete subcortical and cortical infarctions; pattern B, hemodynamic infarctions, diffuse widespread white matter lesions, lacunae and basal ganglia infarctions).

METHODS

Four hundred nineteen carotid plaques (315 patients), producing 50% to 99% stenosis on duplex scanning, were studied. These plaques were imaged on duplex scanning, captured, digitized, and normalized (standardized) in a computer. Subsequently, their gray scale median (GSM) was evaluated to distinguish quantitatively the hypoechoic (low GSM) from the hyperechoic (high GSM) plaques. The brain CT infarction patterns of A, B, or normal CT on the ipsilateral hemisphere were noted.

RESULTS

The pattern A brain CT infarction was associated with carotid plaques having median GSM of 11 and median degree of stenosis of 80%, as contrasted with pattern B (median GSM, 28.5; median degree of stenosis, 75%) or normal CT (median GSM, 22; median degree of stenosis, 75%) (Kruskal-Wallis test, P <.001 for the GSM and P =.002 for the degree of stenosis). In the logistic regression analysis only the GSM and not the degree of stenosis distinguished the plaques associated with the three CT patterns.

CONCLUSIONS

The pattern A brain CT infarction was associated with hypoechoic plaques suggesting an involvement of extracranial carotid artery embolization, whereas the pattern B was associated with hyperechoic plaques suggesting an involvement of other mechanisms (hemodynamic, intracranial small and large vessel disease).

Reproducibility of computer-quantified carotid plaque echogenicity: can we overcome the subjectivity?

BACKGROUND AND PURPOSE

We sought to assess the reproducibility, interobserver variability, and application to clinical studies of a new method for the quantitative assessment of carotid plaque echogenicity.

METHODS

Carotid plaques were scanned with the use of ultrasound, and their images were stored in a computer. They were normalized by assigning certain gray values to blood and adventitia, and the gray scale median (GSM) was used to quantify their echogenicity. The variability between storage media, between degrees of magnification, and between probes was assessed. The method was applied to 232 asymptomatic carotid plaques causing 60% to 99% stenosis in relation to the presence of ipsilateral CT-demonstrated brain infarcts. In all parts of the study the plaque GSM was measured before and after normalization to evaluate its effect. Interobserver agreement for the scanning process was assessed.

RESULTS

The GSM mean difference before and after normalization for variability studies of storage media, degrees of magnification, and probes was -14.5 and -0.12, 2.24 and 1.68, and -8.3 and -0.7, respectively. The median GSM of plaques associated with ipsilateral nonlacunar silent CT-demonstrated brain infarcts was 14, and that of plaques that were not so associated was 30 (P:=0.003). The interobserver GSM difference was -0.05 (95% CI, -1.7 to 1.6).

CONCLUSIONS

Our method decreases the variability between storage media and between probes but not the variability between degrees of magnification. It separates echomorphologically the carotid plaques associated with silent nonlacunar CT-demonstrated brain infarcts from plaques that are not so associated.

Carotid disease in patients scheduled for coronary artery bypass: analysis of 678 patients

The purpose of this article is to investigate the frequency of carotid disease and to identify high-risk groups among patients scheduled for isolated coronary artery bypass grafting (CABG) procedures under nonemergent conditions. A total of 678 consecutive patients underwent preoperative carotid artery duplex scanning (CADS) before CABG procedures. Morphology of carotid artery was determined and five groups were formed. Age, sex, cervical bruit, diabetes mellitus (DM), hypertension, smoking, history of cerebrovascular event (CVE), peripheral vascular disease (PVD), and severity of coronary artery disease were investigated to describe the high-risk group for carotid artery disease. In 41% of patients carotid examination produced normal findings; 46.2% had less than 60% luminal stenoses, 7.1% had 60-79% stenoses, 4.6% had 80-99% stenoses, and 1.2% had total occlusion. Previous cerebral ischemic events (CVE) (p<0.05), hypertension (p < 0.01), smoking (p < 0.01), advanced age (p < 0.01), and female sex (p < 0.01) were identified as high-risk factors for carotid artery stenoses. There was a linear association between carotid disease and coronary disease (p < 0.05). Documentation of previous CVE, hypertension, smoking, advanced age, female sex, and severe coronary artery disease may be helpful in identifying patients at high risk for carotid artery stenoses.

Microemboli are not a prerequisite in retinal artery occlusive diseases

PURPOSE

Retinal artery occlusion (RAO) is caused by arterio-arterial or cardiovascular emboli in about 50% of all cases, but the role of non-embolic causes remains unclear.

SUBJECTS AND METHODS

We studied 27 patients with amaurosis fugax (AFX), branch retinal artery occlusion (BRAO), central retinal artery occlusion (CRAO) and anterior ischaemic optic neuropathy (AION). Patients underwent an evaluation of cerebrovascular and cardiovascular risk factors, measurement of haemorheological parameters, and Doppler/duplex sonography including ultrasound detection of cerebral microembolic signals and echocardiography.

RESULTS

Forty-one per cent of the patients had internal carotid atherosclerosis but only one patient had microembolic signals, probably due to a cardiac thrombus. Vascular risk factors, especially hypertension, were present in 82% of the patients correlating with abnormal haemorheological parameters such as increased thrombocyte reactivity.

CONCLUSIONS

Our results indicate that altered haemorheological parameters, especially increased thrombocyte reactivity and vascular risk factors such as arterial hypertension, are non-embolic causes of vascular disease in a significant number of patients with RAO. This should guide diagnostic and therapeutic considerations concerning RAO in cases without proven embolic sources.

Cigarette smoking and other risk factors for silent cerebral infarction in the general population

BACKGROUND AND PURPOSE

Silent cerebral infarctions (SCIs) have a prevalence between 10% and 40% in the transient ischemic attack population and have been associated with increased mortality and morbidity; however, little is known about the prevalence and risk factors for SCI in the general population. This report focuses on the role of cigarette smoking and other risk factors for SCI in the general population.

METHODS

MRI scans were performed on 1737 participants selected from the general population as part of the Atherosclerosis Risk in Communities Study. Smoking status and other major cerebrovascular risk factors were assessed, and associations between smoking status and SCIs were established with the use of ANCOVA.

RESULTS

Overall, the prevalence of SCI in this population aged 55 to 70 years was 11%. Cigarette smoking had an ordered association (P=0.029) with the presence of SCI, with the odds ratio (OR) of nonsmoking participants exposed to environmental tobacco smoke being 1.06 (95% confidence interval [CI], 0.64 to 1.75) times as great as for nonsmokers not exposed; the OR of past smokers was 1.16 (95% CI, 0.74 to 1.83) times greater, and the OR of current smokers was 1.88 (95% CI, 1.13 to 3.13) times greater. An increased prevalence was also noted among black, older, and hypertensive participants.

CONCLUSIONS

This report is among the first to examine the risk factors for SCI in the general population and finds a relatively high overall prevalence (11%). There is an ordered relationship between increasing exposure to cigarette smoke and the presence of SCI that parallels the relationship between smoking and carotid atherosclerosis. The magnitude of the association with smoking is substantial compared with the effect of hypertension and other traditional cerebrovascular risk factors. The reduction in prevalence of SCI between current and past smokers and the trend that increased pack-years of smoking is related to increased prevalence of SCI are both additional arguments for smoking avoidance and cessation.

Silent stroke and carotid stenosis

BACKGROUND AND PURPOSE

Silent cerebral infarction is often found on computed tomographic scan in patients with asymptomatic carotid stenosis, but its relation to the arterial stenosis is uncertain.

METHODS

We compared computed tomographic scans and carotid Doppler in 115 patients with asymptomatic carotid stenosis, 203 with carotid transient ischemic attacks and carotid stenosis, and 63 with transient ischemic attacks but without carotid stenosis. There was no group with normal carotid arteries for comparison.

RESULTS

Lesions seen on CT scan were most common in the transient ischemic attack with carotid stenosis group (47%) compared with the other groups (30%, 19%) (p less than 0.001). Cerebral infarcts ipsilateral to the carotid stenosis were found in 10% of patients with mild (35-50%) stenosis, 17% in moderate (50-75%) stenosis, and 30% with severe (greater than 75%) carotid stenosis (p less than 0.001). In patients with asymptomatic carotid stenosis, 68% of infarcts were ipsilateral to the stenosis; in those with transient ischemic attacks and carotid stenosis, 86% of infarcts were ipsilateral to the stenosis.

CONCLUSIONS

The more severe the carotid stenosis, the higher the incidence of cerebral infarction ipsilateral to the stenosis. This finding applied to central infarcts as well as to peripheral infarcts in both symptomatic and asymptomatic patients. Silent cerebral infarction may be an indication for carotid endarterectomy in asymptomatic patients.

Extended use of cranial CT in the evaluation of patients with stroke and transient ischaemic attacks

The hypothesis was explored that patterns of ischaemic brain damage shown by CT may be of greater value in estimating the relevance of angiographic stenosis in the carotico-vertebral arteries in some patients than presenting clinical features. Five angiographic and six CT abnormalities were defined and charted independently in a blinded manner in 312 patients whom clinical features and subsequent management were known. Charts were combined for statistical analysis. Statistically significant associations were found between two types of CT lesion and angiographic abnormalities, but these were present in only 18% of cases. The distribution of clinical features did not differ significantly within this subset compared to the whole population, from which it was concluded that the hypothesis was upheld. Furthermore significantly more patients in this subset were subjected to carotid endarterectomy, suggesting that management decisions may have been modulated by CT findings in some patients.

The silent brain infarct before and after carotid surgery

Routine computed tomography was prospectively performed pre- and postoperatively in 114 consecutive patients undergoing a total of 131 procedures on the carotid artery. Hemispheric cerebral infarction was found preoperatively in three of the 16 hemispheres corresponding to symptomatic lesions (19%), in 18 of 109 hemispheres corresponding to transient ischemic attacks (16.5%), and in one of four hemispheres corresponding to lesions responsible for a fixed cerebral vascular accident (25%). Two surgical procedures (1.5%) were complicated by early cerebral infarctions as detected on postoperative computed tomographic scan. These complications resulted in death in one case, and left the patient with major sequelae in the other. Five procedures (3.8%) were complicated by transient ischemic attacks, three of which were associated with minimal cerebral infarctions visible on computed tomographic scan. Neurologic status was unchanged after 124 (94.6%) procedures, whereas four of these procedures were complicated by silent brain infarctions as visualized on postoperative computed tomographic scans (3.1%). This study confirms that existing pre- and postoperative neurologic classifications are far from perfect and that surgery is rarely responsible for cerebral infarction. Carotid surgery should no longer be performed without obtaining pre- and postoperative computed tomographic scans.

Regional cerebral blood flow (rCBF) and cerebral vasoreactivity in patients with retinal ischaemic symptoms

Regional cerebral blood flow (rCBF) and cerebral vasoreactivity were assessed in 28 consecutive patients who presented with retinal ischaemic symptoms, without clinical or cerebral CT evidence of cerebral ischaemia. rCBF was measured using xenon-133 inhalation and single photon emission computed tomography before and 20 minutes after the intravenous administration of 1 g acetazolamide. The findings suggest that patients with retinal ischaemic symptoms alone due to carotid atherosclerosis often have a carotid lesion which is of haemodynamic significance with regard to cerebral perfusion and vasoreactivity. Furthermore, localized areas with reduced cerebral perfusion may also be present in some patients, without evidence of precerebral carotid occlusive disease.