Are Spontaneous Cerebral Microemboli Consistent in Carotid Disease? (original) (raw)
Related papers
Stroke, 2005
Background and Purpose-Carotid endarterectomy clearly benefits patients with symptomatic severe stenosis (SCS), but the risk of stroke is so low for asymptomatic patients (ACS) that the number needed to treat is very high. We studied transcranial Doppler (TCD) embolus detection as a method for identifying patients at higher risk who would have a lower number needed to treat. Methods-Patients with carotid stenosis of Ն60% by Doppler ultrasound who had never been symptomatic (81%) or had been asymptomatic for at least 18 months (19%) were studied with TCD embolus detection for up to 1 hour on 2 occasions a week apart; patients were followed for 2 years. Results-319 patients were studied, age (standard deviation) 69.68 (9.12) years; 32 (10%) had microemboli at baseline (TCDϩ). Events were more likely to occur in the first year. Patients with microemboli were much more likely to have microemboli 1 year later (34.4 versus 1.4%; PϽ0.0001) and were more likely to have a stroke during the first year of follow-up (15.6%, 95% CI, 4.1 to 79; versus 1%, 95% CI, 1.01 to 1.36; PϽ0.0001). Conclusions-Our findings indicate that TCDϪ ACS will not benefit from endarterectomy or stenting unless it can be done with a risk Ͻ1%; TCDϩ may benefit as much as SCS if their surgical risk is not higher. These findings suggest that ACS should be managed medically with delay of surgery or stenting until the occurrence of symptoms or emboli.
Cerebral microembolism in symptomatic and asymptomatic high‐grade internal carotid artery stenosis
Neurology, 1994
Using transcranial Doppler (TCD) ultrasonography in patients with high-grade (>=70%) internal carotid artery (ICA) stenosis, we examined the relation between the rate of TCD-detected silent microembolism of the ipsilateral middle cerebral artery and a history of recent (<121 days) ischemic symptoms attributable to the diseased ICA. In the so-defined neurologically symptomatic group (n = 33 patients), silent microembolic events occurred in 27 subjects (overall mean rate, 14/h ± 29). Among 56 neurologically asymptomatic patients matched for the degree of ICA stenosis, only nine showed such events (overall mean rate, 0.35/h ± 1.4). Across all 89 patients studied, an individual microembolic event rate ≥2/h had a positive predictive value of 0.88 for a history of recent symptoms. Our data suggest that TCD monitoring can provide reliable paraclinical evidence of “unstable ICA disease.”
2010
Background and Purpose-Carotid endarterectomy clearly benefits patients with symptomatic severe stenosis (SCS), but the risk of stroke is so low for asymptomatic patients (ACS) that the number needed to treat is very high. We studied transcranial Doppler (TCD) embolus detection as a method for identifying patients at higher risk who would have a lower number needed to treat. Methods-Patients with carotid stenosis of Ն60% by Doppler ultrasound who had never been symptomatic (81%) or had been asymptomatic for at least 18 months (19%) were studied with TCD embolus detection for up to 1 hour on 2 occasions a week apart; patients were followed for 2 years. Results-319 patients were studied, age (standard deviation) 69.68 (9.12) years; 32 (10%) had microemboli at baseline (TCDϩ). Events were more likely to occur in the first year. Patients with microemboli were much more likely to have microemboli 1 year later (34.4 versus 1.4%; PϽ0.0001) and were more likely to have a stroke during the first year of follow-up (15.6%, 95% CI, 4.1 to 79; versus 1%, 95% CI, 1.01 to 1.36; PϽ0.0001). Conclusions-Our findings indicate that TCDϪ ACS will not benefit from endarterectomy or stenting unless it can be done with a risk Ͻ1%; TCDϩ may benefit as much as SCS if their surgical risk is not higher. These findings suggest that ACS should be managed medically with delay of surgery or stenting until the occurrence of symptoms or emboli.
Detection of intracranial emboli in patients with carotid disease
European Journal of Vascular Surgery, 1994
Transcranial Doppler emboli signal detection has been reported in several patient groups, including patients with symptomatic internal carotid artery stenosis. The potential of this technique in assessing embolic risk and selecting patients for surgery was examined in this study. Selected patients with symptomatic internal carotid artery stenosis underwent combined extracranial and transcranial Doppler study in the Vascular Surgery and Neurovascular Unit. Patients and normal controls were monitored with transcranial Doppler over both middle cerebral arteries. Severity of carotid disease was diagnosed with colour Duplex ultrasound examination or angiography. Selected patients underwent cranial computed tomography and transthoracic echocardiography. Patients undergoing carotid endarterectomy were reexamined one month after surgery. Fifty symptomatic patients, six asymptomatic patients and 30 normal controls were examined. Carotid disease was unilateral in 34 and bilateral in 22 cases. Emboli signals were detected in 94% of patients. The emboli signal count in patients with unilateral carotid stenosis was significantly higher in the middle cerebral artery distal to the stenosed internal carotid compared to the contralateral middle cerebral artery [14 (10-22) versus 2 (0-7) signals per hour, median and 95% confidence intervals, p < 0.001] and in symptomatic compared to asymptomatic cerebal hemispheres 115 (11-21) versus 4 (2-9) signals per hour, p < 0.001]. Emboli were detected in the contralateral middle cerebral artery, in 40% of patients with unilateral carotid disease, in 85% of whom an additional embolic source was identified. No emboli signals were detected after carotid endarterectomy distal to the operated internal carotid, or in any of the normal controls. In conclusion, intracranial emboli signals are common in patients with carotid stenosis. Carotid endarterectomy eliminates emboli signals distal to the operated internal carotid. The clinical significance of these signals remains to be determined by prospective studies.
Microembolism in Carotid Artery Disease
Echocardiography, 1996
Abnormal high intensity transient signals detectable with transcranial Doppler (TCD) sonography have been associated with formed cerebral microembolism. Using long-term TCD monitoring, these clinically silent microembolic events can be observed in patients with cerebrovascular disease. Downstream of high grade internal carotid artery (ICA) stenosis, they occur significantly more frequently in neurologically symptomatic than in asymptomatic patients. Although the occurrence of microemboli is random, the individual rate underlies circadian fluctuations and seems to decline within the first weeks after an ischemic event. Pathoanatomic work suggests that luminal ulcer and thrombosis of the stenosed ICA are the major sources of microemboli. Thus, by tapping into an important pathomechanism, the detection of clinically silent cerebral microembolism appears to provide paraclinical evidence of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;unstable carotid artery disease&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and may help to evaluate more specific treatment strategies. (ECHOCARDIOGRAPHY, Volume 13, September 1996)
Transcranial Doppler test for evaluation of cerebral artery embolism: Microemboli detection
Srpski arhiv za celokupno lekarstvo, 2008
About one third of ischaemic cerebrovascular diseases have embolic properties. Because of that, transcranial Doppler (TCD) test for detection of microembolic signals (MES), as the only one method for detection of microemboli, is a very important test for the evaluation of cerebral artery embolism. Cerebral emboli are particles of thrombus or atheromatous plaque, platelet aggregates, lipid or air particles in cerebral circulation, which can occlude arterioles and cause ischemic transient attack (TIA) or stroke. Most frequently, they derive from exulcerated plaques of the carotid bifurcation or the aortic arch, from the atrial thrombus, prosthetic heart valves, as well as during carotid endarterectomy, arterial stent, aortocoronary by-pass. For MES detection, bilateral monitoring of a. cerebri mediae (ACM) is performed with each probe held in place over a temporal bone. MES are represented as brightly coloured embolic tracks as they pass through the insonated arteries. A computer hard...
Symptomatic Carotid Occlusion Is Frequently Associated With Microembolization
Stroke, 2017
Symptomatic carotid artery disease is associated with significant morbidity and mortality. The pathophysiologic mechanisms of cerebral ischemia among patients with carotid occlusion remain underexplored. We conducted a prospective observational cohort study of patients hospitalized within 7 days of ischemic stroke or transient ischemic attack because of ≥50% carotid artery stenosis or occlusion. Transcranial Doppler emboli detection was performed in the middle cerebral artery ipsilateral to the symptomatic carotid. We describe the prevalence of microembolic signals (MES), characterize infarct topography, and report clinical outcomes at 90 days. Forty-seven patients, 19 with carotid occlusion and 28 with carotid stenosis, had complete transcranial Doppler recordings and were included in the final analysis. MES were present in 38%. There was no difference in MES between those with carotid occlusion (7/19, 37%) compared with stenosis (11/28, 39%; P=0.87). In patients with radiographic ...
Predictive and Clinical Value of Cerebral Microemboli Detection in Cardiac Patients
2008
Background and Aim: Cardioembolic strokes have a worse prognosis and produce larger and more disabling strokes than other ischemic stroke subtypes. We sought to evaluate the prevalence of High-intensity-transient-signals (HITS) in patients having different cardiac sources of emboli and the value of transcranial Doppler (TCD) in stroke prediction. Subjects and Methods: consecutive cardiac patients were subjected to ECG, transthoracic echocardiography, and TCD examination. Results: a total of 45 cardiac patients were investigated; twenty patients with rheumatic heart disease, 10 with prosthetic valves, and 15 with myocardial ischemia. In all patients, the presence of HITS was not affected by the patients' age, gender, the presence of risk factors, the platelet count or the INR level. Cerebral strokes were significantly higher in patients with HITS than those without. In patients with prosthetic heart valves, 60% was HITS-positive with a mean rate of 14.2±6.49/ 30 minutes, which wa...
European Journal of Vascular and Endovascular Surgery, 1997
Objectives: Perioperative ischaemic stroke is the leading cause of morbidity and mortality associated with carotid endarterectomy (CEA). The aim was to test the hypotheses that the detection of microembolic ultrasonic signals (MES) with transcranial Doppler ultrasound (TCD) during and after the operation may be of value in identifying patients at increased perioperative stroke risk. Design: Open prospective case series. Patients and Methods: Eighty-one consecutive patients undergoing CEA with TCD monitoring. Preoperative, intraoperative and interval postoperative TCD monitoring of the middle cerebral artery (MCA) ipsilateral to the operated carotid artery. On-line pre-and intraoperative MES counting and blinded off-line analysis of postoperative MES counts. End-points were any focal neurological deficit and death at 30 days postoperatively. Results" MES were detected in 94% of patients intraoperatively and 71% of cases during the first postoperative hour. MES counts ranged from 0 to 25 per operative phase (range of median counts 0-8) and from 0 to 212 per hour postoperatively (range of median counts 0-4). Eight cases (10%) developed postoperative MES counts greater than 50/h. Five of these eight cases evolved ischaemic neurological defi'cits in the territory of the insonated MCA, indicating a strong association between frequent postoperative microembolism and the development of early cerebral ischaemia O~ 2 =34.2, p<O.O001). Intraoperative MES were not associated with clinical outcome measures. Conclusions: MES counts of greater than 50/h in the early postoperative phase of carotid endarterectomy are predictive of the development of ipsilateral focal cerebral ischaemia.
Source of Microembolic Signals in Patients With High-Grade Carotid Stenosis
Stroke, 2002
Background and Purpose-In patients with both symptomatic and asymptomatic carotid artery stenoses, the relationship between carotid plaque characteristics and transcranial Doppler (TCD)-detected microembolic signals (MES) is unclear. The purpose of this study was to examine the relationship between macroscopically described plaque characteristics and MES in patients undergoing carotid endarterectomy. Methods-Sequential patients scheduled for carotid endarterectomy underwent preoperative 30-minute TCD monitoring of the ipsilateral middle cerebral artery to detect MES. TCD signal analysis, by researchers who were blinded to patient information, was performed offline. Clinical variables of patients and macroscopic carotid plaque features seen at surgery were documented prospectively. Results-Of the 109 patients (74 male, 35 female; mean age, 68.8Ϯ8.7 years) enrolled, 71 had ipsilateral carotid territory symptoms. MES were detected in 27 of all patients (25%). Twenty-two of 71 symptomatic patients (31%) compared with 5 of 38 asymptomatic patients (13%) had MES (Pϭ0.046). Also, symptomatic patients had more emboli (total MES counts) than asymptomatic patients (Pϭ0.010). The presence or absence of MES was not associated with plaque characteristics. Conclusions-Our data do not confirm previous reports of an association between MES and macroscopic plaque characteristics. We hypothesize that smaller platelet aggregates and fibrin clots, which are not detected macroscopically, are the most likely sources of TCD-detected MES.