Transcranial Doppler waveform blunting in severe extracranial carotid artery stenosis

OBJECTIVE: To investigate the frequency of transcranial Doppler (TCD) waveform blunting in patients with severe (80-99%) symptomatic or asymptomatic extracranial carotid artery stenosis. BACKGROUND: Severe carotid artery stenosis has been identified as a risk factor for ischemic stroke. Blunted Doppler flow waveforms (reduced systolic flow velocity and pulsatility) of the middle cerebral artery (MCA) are inferred to reflect hemodynamic impairment, possibly indicating an increased risk of stroke. METHODS: The 114 consecutive patients (mean age 72.4 years, SD 9.0 years; 37% women; 46 clinically symptomatic, 68 asymptomatic) with 80-99% stenosis of the extracranial internal carotid artery (ICA), as determined by duplex sonography, were examined with TCD. Flow velocities, pulsatility index, and spectral waveforms of the MCA distal to the ICA stenosis were assessed blinded to the clinical status of the ICA: Doppler waveform blunting was defined as loss of the characteristic systolic peak. Odds ratios with 95% confidence intervals and chi(2) statistics were used to describe the association between waveform blunting and the symptomatic status of the ICA stenosis. RESULTS: Among symptomatic patients, 23 (50%) had completed strokes, and a further 23 (50%) had transient neurologic deficits in the territory of the stenotic ICA. Blunted spectral waveform was found in 37 (80%, 95% CI 68-92%) of the symptomatic and 25 (37%; 95% CI 25-49%) of the asymptomatic patients. Symptomatic patients had significantly increased odds of having blunted TCD waveforms (OR 7.5, 95% CI 3.1-18.1, p < 0.001). CONCLUSIONS: Our findings suggest that TCD waveform blunting in the MCA as here described may be an additional risk factor in the setting of severe extracranial carotid artery stenosis. A prospectively designed study to confirm our results seems warranted.     

Association of intraoperative transcranial doppler monitoring variables with stroke from carotid endarterectomy

BACKGROUND AND PURPOSE: The outcomes of carotid endarterectomy (CEA) are, in addition to patient baseline characteristics, highly dependent on the safety of the surgical procedure. During the successive stages of the operation, transcranial Doppler (TCD) monitoring of the middle cerebral artery (MCA) was used to assess the association of cerebral microembolism and hemodynamic changes with stroke and stroke-related death. METHODS: By use of data pooled from 2 hospitals in the United States and the Netherlands, including 1058 patients who underwent CEA, the association of various TCD emboli and velocity variables with operative stroke and stroke-related death was evaluated by univariable and multivariable logistic regression analyses in combination with receiver operating characteristic (ROC) curve analyses. The impact of basic patient characteristics, such as age, sex, preoperative cerebral symptoms, and ipsilateral and contralateral internal carotid artery stenosis, on the prediction of operative stroke was also evaluated. RESULTS: We observed 31 patients with ischemic and 8 patients with hemorrhagic operative strokes. Four of these patients died. Emboli during dissection (odds ratio [OR] 1.5, 95% CI 0.8 to 2.9) and wound closure (OR 2.3, 95% CI 1.2 to 4.4) as well as > or =90% decrease of MCA peak systolic velocity at cross-clamping (OR 3.3, 95% CI 1.3 to 8.5) and > or =100% increase of the pulsatility index of the Doppler signal at clamp release (OR 7.1, 95% CI 1.4 to 35.7) were independently associated with stroke. The ROC area of this model was 0.69. Of the patient characteristics, only preoperative cerebral ischemia (OR 1.9, 95% CI 1.0 to 3.7) and > or =70% ipsilateral internal carotid artery stenosis (OR 0.5, 95% CI 0.2 to 0.9) were associated with stroke. Adding these patient characteristics to the model, the area under the ROC curve increased to 0.73. CONCLUSIONS: In CEA, TCD-detected microemboli during dissection and wound closure, > or =90% MCA velocity decrease at cross-clamping, and > or =100% pulsatility index increase at clamp release are associated with operative stroke. In combination with the presence of preoperative cerebral symptoms and > or =70% ipsilateral internal carotid artery stenosis, these 4 TCD monitoring variables reasonably discriminate between patients with and without operative stroke. This supports the use of TCD as a potential intraoperative monitoring modality to alter the surgical technique by enhancing a decrease of the risk of stroke during or immediately after the operation.     

Cerebral hemodynamics after contralateral carotid endarterectomy in patients with symptomatic and asymptomatic carotid occlusion: a 10-year follow-up.

We sought to investigate whether carotid endarterectomy (CEA) can achieve long-term cerebral hemodynamic improvement and reduce recurrence of cerebral ischemic events in symptomatic and asymptomatic patients with severe (>70%) carotid artery stenosis contralateral to carotid occlusion (CO). Thirty-nine patients with severe carotid lesion contralateral to CO were studied before (1 day) and after CEA (at 7 days, 1, 3 and 6 months, and then yearly thereafter). Collateral flow and cerebral vasomotor reactivity (VMR) were assessed by transcranial Doppler sonography (TCD). A total of 32 unoperated patients with severe carotid lesion contralateral to CO, who were comparable with respect to age and sex, served as a control group. The average period of TCD follow-up was 10 years and was obtained in all patients; during this period, major clinical events (stroke, acute myocardial infarction and death) were also recorded. The proportion of patients with collateral flow via the anterior communicating artery increased significantly from 61.5% before to 89.7% after CEA (P = 0.01). Cerebral VMR ipsilateral to CO improved in 85.7% of patients (30 of 35) within 30 days of CEA, and in all patients within 90 days. No significant spontaneous VMR recovery was recorded in the control group. After the initial recovery, no significant change in VMR was observed in the surgical group or the control group during the follow-up. In conclusion, in patients with severe carotid stenosis, CEA contralateral to symptomatic and asymptomatic CO determines a durable cerebral hemodynamic improvement not only on the side of the CEA but also on the contralateral side, with no difference between symptomatic and asymptomatic patients.     

Natural history of asymptomatic carotid artery stenosis

The prevalence of carotid artery stenosis 50% or greater increases from about 1% in people aged 50 to 59 to about 10% in people older than 70. Although carotid stenosis accounts for about 10% of ischemic strokes, only a minority of patients with carotid stenosis will have a stroke. The annual risk of ipsilateral ischemic stroke is relatively low, ranging from 1.0 to 3.8% and is about half of that of any stroke. There is a relatively weak relationship between carotid stenosis severity and risk of ipsilateral stroke. In addition to stenosis severity, carotid plaque composition, which can be evaluated by several noninvasive imaging methods, may be an independent risk factor for stroke. There are few data supporting the use of hemodynamic impairment assessment to predict stroke risk. Nonstroke vascular events are about twice as likely in patients with carotid bruits compared with those without. Patients with asymptomatic carotid stenosis have a particularly high risk of cardiac events (about 3.5% per year). Therefore, the most important part of the management of patients with carotid stenosis is optimization of medical therapy. Much remains to be done to identify patients at particularly high risk of ipsilateral stroke, for whom carotid endarterectomy may be necessary in addition to medical therapy.     

Clinical carotid atherosclerosis

Atherogenesis is an inflammatory process that begins in childhood. Early detection of atherosclerosis might allow for selection of subjects at risk for future cerebrovascular events at a time when dietary and lifestyle modification may have its greatest impact, and medical intervention may be useful for those who are refractory to such treatment or who are at greater risk for an event. Early detection relies on a knowledge of the distribution of atheroma formation, which can be predicted by understanding the hemodynamic patterns of blood flow. Early formation is accompanied by a vascular remodeling that normalizes the area of the vessel lumen, making early detection impossible by angiography. Elevated serologic markers of inflammation may be used as evidence of formation of atherosclerosis, but inflammatory markers lack sensitivity and specificity. Preliminary evidence supports the ability of MRI to detect early atheroma formation, possibly even before substantial wall thickening occurs. Once atheroma has formed with measurable stenosis, the goal of imaging studies is to predict stroke risk and determine the need for surgical intervention. Subjects with symptomatic high-grade carotid stenosis have been shown to benefit from surgery with a reduced stroke risk when compared with medical management alone, although controversy exists regarding the management of moderate symptomatic carotid stenosis or asymptomatic carotid disease. In these individuals, understanding atheroma morphology may prove to be of greater utility for assessing stroke risk and determining the appropriate management. Morphologic characterization may also be helpful in monitoring the effect of medical intervention. MRI has proven capable of characterizing the morphologic composition of carotid atheroma, although the clinical implications continue to be investigated.     

Bedside Emergency Transcranial Doppler Diagnosis of Severe Carotid Disease Using Orbital Window Examination

BACKGROUND: Identifying internal carotid artery (ICA) stenosis in the acute stroke setting can provide clinically useful information. Transcranial Doppler (TCD) through the orbital window is an easy test to perform and to track and identify different vessels. Previous TCD studies have suggested that a reversed ophthalmic artery (OA) flow is a useful collateral pattern to predict ICA disease. The authors sought to evaluate the TCD orbital window for predicting cervical ICA (cICA) stenosis in the setting of acute stroke and TIA. METHOD: Power M-mode/TCD was performed in acute stroke and transient ischemic attack patients at 2 institutions. Each orbital window depth was detected on M-mode and evaluated for the direction of flow and resistance pattern. Gold standard for comparison was carotid evaluation using carotid duplex, computed tomography angiogram, or conventional angiography. The assessment of cICA disease was categorized by degree of stenosis or occlusion. RESULTS: A total of 216 transorbital exams were performed in 117 patients. Twenty-five cICA occlusions and 8 critical cICA stenoses (>or=95%) were identified by gold standard imaging. Reversed OA flow at 50 to 60 mm depth revealed high specificity (100%; confidence interval [CI], 97.6%-100.0%) and good sensitivity (75%; CI, 53.3%-90.2%) for identifying cICA occlusion or critical stenosis (>or=95%). Low pulsatility index (<1.2) and mean flow velocity (<15 cm/s) discriminated critical severe ICA stenosis or occlusion when OA flow was anterograde with good sensitivity (87.2%) and specificity (95.2%). CONCLUSION: The reversed OA sign at 50 to 60 mm depth is very specific for identifying cICA occlusion or critical stenosis. When OA flow is anterograde, a low mean flow velocity or pulsatility index is also useful to identify cICA critical stenosis or occlusion.     

Asymptomatic embolization predicts stroke and TIA risk in patients with carotid artery stenosis.

BACKGROUND AND PURPOSE: Improved methods of identifying patients at high risk of thromboembolism would allow improved targeting of therapy. One such situation is carotid artery stenosis. This is associated with an increased risk of stroke, which can be reduced by carotid endarterectomy. However, the risk-benefit ratio is low in patients with tight asymptomatic stenosis and moderate symptomatic stenosis. Most stroke in patients with carotid stenosis is believed to be embolic. Therefore, the detection of asymptomatic cerebral emboli using Doppler ultrasound may allow identification of a high-risk group. METHODS: Transcranial Doppler ultrasound was used to record for 1 hour the ipsilateral middle cerebral artery in 111 patients with >60% carotid artery stenosis (69 symptomatic, 42 asymptomatic). The Doppler audio signal was recorded onto digital audio tape for later analysis for embolic signals (ES) by an individual blinded to clinical details. In 67 subjects the relationship between ES and angiographically determined plaque ulceration was investigated. All subjects were followed up prospectively, and the relationship between ES and risk of future ipsilateral carotid artery territory ischemic events (TIA and stroke) was determined. RESULTS: ES were detected in 41(36.9%) subjects. In symptomatic patients there was a significant inverse relationship between the number of ES per hour and time elapsed since last symptoms (Spearman's rho=-0.2558, P=0.034). ES were more common in subjects with plaque ulceration, with a relative risk of 4. 94 (95% CI, 1.23 to 19.84; P=0.025) after controlling for both symptomatic status and degree of stenosis. The presence of ES at entry was predictive of TIA and stroke risk during follow up in both symptomatic (P=0.02) and asymptomatic patients (P=0.007). Considering all 111 patients, the presence of asymptomatic embolization was predictive of a further ischemic event, with an adjusted OR of 8.10 (95% CI, 1.58 to 41.57; P=0.01) after controlling for other cardiovascular risk factors, degree of stenosis, symptomatic status, and aspirin or warfarin use. CONCLUSIONS: Asymptomatic embolization in patients with carotid artery stenosis correlates with known markers of increased stroke risk and is an independent predictor of future stroke risk in patients with both symptomatic and asymptomatic carotid stenosis. It may allow identification of a high-risk group of patients who will particularly benefit from carotid endarterectomy. A large multicenter study is now required to confirm these findings.     

颈动脉内膜切除术防治缺血性脑血管病的近远期随访分析

目的 评价颈动脉内膜切除术防治缺血性脑血管病的近远期疗效。方法 14例有症状的重度颈动脉狭窄患者接受了颈动脉内膜切除术,对13例患者进行了3月～5年的随访。每位患者来院复查时行全面神经系统检查及TCD、颈动脉彩色多普勒超声检查,在随访过程中均行DSA检查1次。结果 13例随访病例在随访期间均无中风发生。除2例患者外,其余均无TIAs。TCD、颈动脉彩色多普勒超声检查和DSA检查发现2例再狭窄,其中1例无症状,另1例有TIAs,予内科保守治疗。结论 颈动脉内膜切除术是防治缺血性脑血管病的有效方法。多普勒超声检查是首选的有效的无创检查方法。TCD对病变的诊断有辅助作用。     

Vascular risks of asymptomatic carotid stenosis

BACKGROUND AND PURPOSE: We sought to determine the risks of stroke, myocardial ischemia, and vascular death in patients with asymptomatic carotid stenosis. METHODS: Six hundred ninety-six patients with asymptomatic carotid stenosis referred to the Doppler laboratory were followed prospectively for a mean time of 41 months. These patients were studied both clinically and by carotid Doppler ultrasound, including evaluation of the effect of stroke risk factors. RESULTS: Transient ischemic attacks occurred in 75 patients and stroke in 29, while 132 had ischemic cardiac events. Five patients died from stroke and 59 from cardiac causes. Annual stroke rate was 1.3% in patients with carotid stenosis less than or equal to 75% and 3.3% in those with stenosis greater than 75%. Ipsilateral stroke rate was 2.5% in patients with greater than 75% carotid stenosis. Annual cardiac event rate was 8.3% and death rate 6.5% in patients with severe carotid stenosis. CONCLUSIONS: With carotid stenosis less than or equal to 75%, the stroke rate is negligible (1.3% annually) whereas the combined risk of cardiac ischemia and vascular death is as high as 9.9%. With stenosis greater than 75%, combined transient ischemic attack and stroke rate is 10.5% per year, with 75% of events ipsilateral to the stenosed artery.     

Long-term risk of stroke and other vascular events in patients with asymptomatic carotid artery stenosis

CONTEXT: The annual risk of ischemic stroke in patients with asymptomatic carotid artery stenosis is about 2% during the short-term (2-3 years), but the long-term risks of stroke and other vascular events are unknown, although they may affect surgical decision making. OBJECTIVE: To evaluate the long-term risk of stroke and other vascular events in patients with asymptomatic carotid artery stenosis. DESIGN: Cohort study with a median follow-up of 10 years (range, 5-18 years). SETTING: The teaching hospital of the University of Toronto, Toronto, Ontario. PATIENTS: From the initial cohort of 500 patients, 106 patients with asymptomatic carotid artery stenosis were selected because they had completed at least 5 years of follow-up. MAIN OUTCOME MEASURES: Ipsilateral stroke, myocardial infarction, and nonstroke vascular death. RESULTS: The 10- and 15-year actuarial risks of ipsilateral stroke were 5.7% (95% confidence interval [CI], 0%-12%) and 8.7% (95% CI, 1%-17%), respectively, in patients with 0% to 49% internal carotid artery stenosis, and 9.3% (95% CI, 1%-18%) and 16.6% (95% CI, 1%-32%) in patients with 50% to 99% internal carotid artery stenosis. The 10- and 15-year risks of myocardial infarction and nonstroke vascular death were 10.1% (95% CI, 4%-16%) and 24.0% (95% CI, 14%-34%). Age (P =.02), diabetes mellitus (P =.02), and internal carotid artery stenosis of 50% or more (P =.04) were predictive of increased risks of myocardial infarction and nonstroke vascular death. Internal carotid artery stenosis of 50% or more did predict the risk of ipsilateral stroke (P =.003) when all 181 asymptomatic carotid arteries were included. CONCLUSIONS: The annual stroke risk in patients with asymptomatic carotid artery stenosis was low and remained stable during long-term follow-up. Any benefit from carotid surgery is therefore unlikely to increase significantly with long-term follow-up. The high long-term risks of myocardial infarction and nonstroke vascular death suggest that prevention strategies should concentrate on coronary risk more than stroke risk.     

Stroke risk and critical carotid stenosis.

The risk of stroke from carotid stenosis is proportionate to the degree of stenosis, but whether this is a direct and linear relationship is unknown. Using the degree of carotid stenosis in 500 patients with asymptomatic carotid bruits as a continuous variable, we plotted the frequency distribution and related this to the risk of ischaemic cerebral events and the progression of the arterial lesion. There was a bi-modal distribution, with the junction of the two populations at 85% stenosis. The frequency of ischaemic cerebral events was maximal at 75-90% stenosis. Our data suggest that there is a critical degree of carotid stenosis at which stroke risk becomes maximal. This may represent a window of therapeutic opportunity.     

Endarterectomy, best medical treatment or both for stroke prevention in patients with asymptomatic carotid artery stenosis

Carotid endarterectomy (CEA) is currently frequently performed in subjects with asymptomatic carotid artery stenosis over 70%, as clinical trials like the Asymptomatic Carotid Atherosclerosis Study and Asymptomatic Carotid Surgery Trial demonstrated a significant benefit for stroke prevention. A low risk reduction in the long-term prevention of stroke or death and the required lower than 3% of surgical risk are associated with surgery. That means that an important number of patients needs to be operated to prevent 1 stroke over 5 years (number needed to treat: 21) with an absolute risk reduction of 5.4%. It is reasonable to consider CEA for patients aged 40-75 years and with asymptomatic stenosis of 60-99%, for patients with a life expectancy of at least 5 years, and in centres with a surgical morbidity-mortality of less than 3%. Therefore, it is of interest to identify high-risk patients with asymptomatic carotid stenosis who will more likely benefit from surgery. Techniques such as ultrasound or magnetic resonance imaging may identify plaque morphology or detect clinically asymptomatic embolization. CEA combined with the best medical treatment and good management of modifiable risk factors might be superior to medical management alone or surgery in preventing stroke. There is no level I evidence to support carotid artery stenting in asymptomatic carotid stenosis even in a subgroup of patients with a high surgical risk.     

Acetylsalicylic acid and microembolic events detected by transcranial Doppler in symptomatic arterial stenoses

BACKGROUND: In patients with symptomatic carotid artery stenosis, high-intensity transient signals detected by transcranial Doppler (TCD) have been related to particulate microemboli originating at the stenotic lesion. The occurrence of these microembolic events within the Doppler spectrum should be influenced by antithrombotic agents of proven efficacy in these patients mainly by reducing cerebral embolism. METHODS: Seventy-four of 192 consecutive patients with symptomatic arterial stenosis in the anterior circulation and clinical symptoms within the last 30 days underwent 1-hour bilateral TCD monitoring. Patients were selected, if they presented temporal bone windows enabling transcranial insonation, revealed normal Doppler CO2 test excluding hemodynamic impairment, had not received antithrombotic therapy other than acetylsalicylic acid (ASA) before sonographic examination, and gave informed consent to 1-hour monitoring which could be performed immediately on admission/presentation of the patient at the Department of Neurology. RESULTS: Microembolic events were detected in 38 patients (51%). The proportion of patients with events among 26 patients without antithrombotic medication was 73% as compared with 40% in 48 patients receiving ASA at the time of TCD monitoring (p = 0.023). Multivariate analysis including time from ischemia to TCD, presence and start of ASA prevention, degree and localization of stenosis, and presence of a single or recurrent ischemia revealed that absence of an ASA prevention (odds ratio OR 7.1, 95% confidence interval CI 1.6-31.4, p = 0.010), recurrent ischemic events (OR 7.1, 95% CI 1.6-32.7, p = 0.011), and extracranial localization of the stenosis (OR 3.8, 95% CI 1.1-13.2, p = 0.038) were independent predictors for microembolic events. CONCLUSION: In patients with symptomatic arterial stenosis, the absence of an ASA medication is associated with the occurrence of TCD-detected microembolic events, suggesting a relation between these events and ASA-sensitive microemboli from the stenotic lesion.     

经颅多普勒超声和颈动脉超声检测无脑缺血症状的2型糖尿病患者颅内外动脉粥样硬化病变

目的 分析无脑缺血症状的2型糖尿病患者颅内动脉粥样硬化性狭窄和颅外颈动脉粥样硬化病变的发生频率及分布特征,并探讨其危险因素.方法 对94例无脑缺血症状的2型糖尿病住院患者用经颅多普勒超声(TCD)和颈动脉超声判断颅内外动脉粥样硬化病变,颅内动脉只分析狭窄,颅外动脉病变包括颈动脉斑块及狭窄.分析各危险因素的影响.结果 55例(58.5%)有颅内外动脉粥样硬化病变.22例(23.4%)发现有颅内动脉狭窄,明显高于颅外颈动脉狭窄或闭塞(3/94,3.2%,χ~2=16.66,P＜0.01).大脑中动脉是颅内最常受累的动脉(狭窄率17.0%),占狭窄动脉数的58.5%.48例(51.0%)有颅外颈动脉粥样斑块或狭窄.Logistic多元回归分析显示糖尿病病程和合并高血压是颅内外动脉粥样硬化病变的独立危险因素.结论 无脑缺血症状的2型糖尿病住院患者,半数以上有颅内外动脉粥样硬化改变,且与糖尿病病程及合并高血压有关,提示对上述高危患者应常规进行超声检测.     

The Prevalence of Asymptomatic Intracranial Large-Vessel Occlusive Disease: The Role of Diabetes

OBJECTIVE: To investigate the prevalence of asymptomatic intracranial stenosis using transcranial Doppler ultrasonography in patients with evidence of asymptomatic carotid stenosis. BACKGROUND: Symptomatic atherosclerotic intracranial largeartery stenosis accounts for approximately 10% of ischemic strokes annually. It is unknown whether a significant risk for stroke is associated with asymptomatic intracranial stenosis, especially in patients with known asymptomatic carotid disease. DESIGN AND METHODS: Transcutaneous real-time B-mode Doppler ultrasonography was performed on 510 patients referred for the evaluation of asymptomatic carotid bruits. A peak systolic flow velocity > 1.40 m/s indicated carotid stenosis. Transcranial Doppler ultrasound was performed to identify intracranial large-artery disease. The peak systolic flow velocity indicating stenosis was > 120 cm/s for anterior circulation and > 100 cm/s for posterior circulation. Demographic and cerebrovascular risk factor information was recorded at the time of examination. Chi-square analysis with Pearson correction was performed to examine the significance of the findings. RESULTS: Five hundred ten patients (252 male, 258 female) aged 71.4 +/- 10.45 years were studied. The laboratory's accuracy was previously established as 93% for each technique for laboratory certification. Two hundred patients (39.2%) were found to have extracranial carotid stenosis, and 66 (12.9%) were found to have intracranial stenosis. Thirty-seven patients (56%, P < .01) were found to have concurrent stenosis. In patients with intracranial stenosis, 19 (28.8%, P < .03) had diabetes, and 26 (39.4%, p < .03) had coronary disease. There was no corresponding correlation with extracranial carotid disease and diabetes or coronary artery disease. CONCLUSIONS: The prevalence of patients with asymptomatic intracranial stenosis with concurrent carotid stenosis was greater than expected. Coexisting diabetes and coronary disease were significant risk factors in this population. Doppler ultrasonography may be a useful technique in delineating asymptomatic intracranial stenosis in those patients with existing carotid stenosis. Further studies are needed to clarify the risk of this population for stroke from asymptomatic intracranial stenosis and to determine optimal therapy.     

Benign prognosis of never-symptomatic carotid occlusion

OBJECTIVE: To determine the prognosis of asymptomatic carotid artery occlusion. BACKGROUND: As opposed to symptomatic carotid occlusion, little information is available on the prognosis of asymptomatic carotid occlusion. METHOD: Thirty never-symptomatic and 81 symptomatic patients with carotid occlusion underwent baseline assessment of 15 risk factors together with PET measurements of oxygen extraction fraction (OEF). Every 6-month telephone contact recorded interval medical treatment and subsequent stroke occurrence during an average follow-up of 32 months. Patients, treating physicians, and an end point adjudicator were blinded to PET results. RESULTS: Ischemic stroke occurred in 1 of 30 of never-symptomatic patients (3.3%) and 15 of 81 of symptomatic patients (18.5%; p = 0.03). No strokes in the carotid territory distal to the occluded vessel occurred in the never-symptomatic patients. Multivariate analysis of baseline risk factors for all 111 patients revealed that age, plasma fibrinogen level, and PET findings of high OEF distal to the occluded carotid artery were the only independent predictors of subsequent stroke (p < 0.05). Previous ipsilateral hemispheric or retinal symptoms was not a significant predictive variable. The lower risk of stroke in never-symptomatic patients was associated with a lower incidence of high OEF (4 of 30) as opposed to symptomatic patients (39 of 81; p = 0.002), but there was no significant difference in age or fibrinogen level. CONCLUSIONS: Never-symptomatic carotid occlusion carries a very low risk of subsequent ischemic stroke. This benign prognosis is associated with a low incidence of cerebral hemodynamic compromise in these patients. These data support further the importance of hemodynamic factors in the pathogenesis of ischemic stroke in patients with carotid occlusion.     

Asymptomatic carotid stenosis: what to do

PURPOSE OF REVIEW: Patients with asymptomatic carotid stenosis are at increased vascular risk but optimal treatment is controversial. We reviewed the current evidence for medical and surgical intervention in these patients. RECENT FINDINGS: Optimal medical treatment is the most important aspect of management of patients with asymptomatic carotid stenosis. On the basis of previous trials, endarterectomy is only of overall benefit in men, and this benefit may now be obviated by improved medical treatment. There is insufficient evidence to advocate the routine use of carotid angioplasty or stenting in patients with asymptomatic stenosis. Inaccuracy in the measurement of carotid stenosis may contribute to conflicting estimates of stroke risk in relation to the degree of asymptomatic stenosis. Advances in noninvasive imaging of plaque morphology and inflammation and the detection of microembolic signals may help to risk stratify patients but data on clinical usefulness are lacking. SUMMARY: Absolute benefit from endarterectomy for asymptomatic carotid stenosis is small, but can sometimes be justified in men. Further research is required to determine long-term benefit in women and to risk stratify patients, particularly in the light of advances in medical treatment.     

2型糖尿病患者无症状的大脑中动脉狭窄的危险因素分析

目的 探讨住院2型糖尿病患者无症状大脑中动脉（MCA）狭窄的相关危险因素。方法回顾性总结227例2型糖尿病住院患者的病历资料，排除合并中风或中风史以及其他颅内疾病患者。用TCD诊断MCA狭窄。结果227例患者中MCA狭窄者共61例，狭窄率（26．9％），狭窄组病人年龄、病程、收缩压、尿酸水平、合并高血压和心电图异常率明显高于非狭窄组；Logistic回归分析显示糖尿病病人的病程以及合并高血压是无症状颅内动脉狭窄的独立危险因素。结论糖尿病病程延长及合并高血压是无症状MCA狭窄的独立危险因素。     

Hemoglobin oxygen saturation as a marker of cerebral hemodynamics in carotid artery occlusion

Cerebral hemodynamics play a pivotal role in stroke pathogenesis. Transcranial Doppler (TCD) studies demonstrated the importance of cerebral vasomotor reactivity (VMR) on the outcome of carotid artery occlusion (CAO). So far, positron emission tomography represents the best technique for detecting both hemodynamic and metabolic aspects of cerebral perfusion adaptive processes in cerebrovascular patients. Near-infrared spectroscopy (NIRS) is a new method allowing for a non-invasive assessment of cerebral blood flow and hemoglobin (Hb) oxygenation parameters.A recent TCD and NIRS study demonstrated that patients with symptomatic CAO had lower VMR values measured by TCD and lower oxygen saturation (oxygen%) increases detected by NIRS than asymptomatic ones. The parameters were obtained simultaneously after CO(2) inhalation. The present study aims to investigate if Hb oxygen % could represent also at rest a marker of hemodynamic status in carotid disease.Thirty-five symptomatic and 17 asymptomatic patients with CAO underwent a simultaneous examination by means of TCD and NIRS at rest condition and during CO(2) reactivity test.Symptomatic patients presented with oxygen% values at rest higher (p = 0.001) and VMR values lower (p < 0.001) than asymptomatic subjects. According to a logistic model, for each unitary VMR increase, the odds of being symptomatic decreases of about 10% (OR = 0.9, p = 0.001); for each unitary increase of oxygen% at baseline, this odd increases of about 23% (OR = 1.23, p = 0.031).In addition to TCD VMR values, oxygen hemoglobin saturation at rest detected by NIRS can discriminate symptomatic from asymptomatic patients with CAO. NIRS can add an important contribution to explain pathophysiological mechanisms of stroke occurrence.     

MMP-9 and/or TIMP as predictors of ischaemic stroke in patients with symptomatic and asymptomatic atherosclerotic stenosis of carotid artery treated by stenting or endarterectomy – A review

We still lack an optimal tool to predict ischaemic stroke in patients with symptomatic and asymptomatic carotid stenosis (CS). It has already been shown that patients at increased risk of ischaemic stroke can be identified based on the elevated plasma levels of metalloproteinases (MMPs) and reduced activity tissue inhibitor of metalloproteinase (TIMP). There are few studies presenting the role of MMP-9 and TIMP in ischaemic stroke both in patients with symptomatic and asymptomatic CS treated with stenting or endarterectomy, however we have not found any published review summarizing the role of abovementioned markers. MEDLINE was accessed via Pub Med, and searched for published studies that analyzed MMP-9 and TIMP levels in patients with asymptomatic and symptomatic internal carotid stenosis and/or examined these parameters as potential risk markers for ischaemic stroke. A total of 13 articles documenting the outcomes of patients with symptomatic or asymptomatic carotid stenosis treated by carotid stenting or endarterectomy, were analyzed. Statistically significant differences in the levels of MMP-9 and/or TIMP in patients with symptomatic and asymptomatic CS have been reported. Also the concentrations of MMP-9 and TIMP in CS patients subjected to stenting or endarterectomy were higher than in baseline group. Moreover higher levels of MMP-9 and decreased TIMP was reported to be associated with the risk of restenosis. This systematic review shows that available evidence regarding the dynamics of MMP-9 and TIMP levels may be a predictor of cerebrovascular events in both symptomatic and asymptomatic carotid stenosis in patients treated with stenting or endarterectomy.