Predictors of Atrial Fibrillation in Patients with Embolic Stroke of Unknown Etiology and Implantable Loop Recorders-Further Insights of the TRACK AF Study on the Role of ECG and Echocardiography.

Aims-Electrocardiography (ECG) and echocardiographic left atrial (LA) parameters may be helpful to assess the risk of atrial fibrillation (AF) in embolic stroke of unknown etiology (ESUS) and could therefore guide intensity of ECG monitoring. Methods-1153 consecutive patients with ischemic stroke or transient ischemic attack (TIA) were analyzed. An internal loop recorder (ILR) was implanted in 104 consecutive patients with ESUS. Multiple morphologic P-wave parameters in baseline 12-channel ECG and echocardiographic LA parameters were measured and analyzed in patients with and without ILR-detected AF. Using logistic regression, we evaluated the predictive value of several ECG parameters and LA dimensions on the occurrence of AF. Results-In 20 of 104 (19%) patients, AF was diagnosed by ILR during a mean monitoring time of 575 (IQR 470-580) days. Patients with AF were significantly older (72 (67-75) vs. 60 (52-72) years; p = 0.001) and premature atrial contractions (PAC) were more frequently observed (40% vs. 2%; p < 0.001) during baseline ECG. All morphologic P-wave parameters did not show a significant difference between groups. There was a non-significant trend towards a larger LA volume index (31 (24-36) vs. 29 (25-37) mL/m2; p = 0.09) in AF patients. Conclusions-Age and PAC are independently associated with incident AF in ESUS and could be used as markers for selecting patients that may benefit from more extensive rhythm monitoring or ILR implantation. In our consecutive cohort of patients with ESUS, neither morphological P-wave parameters nor LA size were predictive of AF.

Photon echoes using atomic frequency combs in Pr:YSO - experiment and semiclassical theory.

Photon echoes in rare-earth-doped crystals are studied to understand the challenges of making broadband quantum memories using the atomic frequency comb (AFC) protocol in systems with hyperfine structure. The hyperfine structure of Pr3+ poses an obstacle to this goal because frequencies associated with the hyperfine transitions change the simple picture of modulation at an externally imposed frequency. The current work focuses on the intermediate case where the hyperfine spacing is comparable to the comb spacing, a challenging regime that has recently been considered. Operating in this regime may facilitate storing quantum information over a larger spectral range in such systems. In this work, we prepare broadband AFCs using optical combs with tooth spacings ranging from 1 MHz to 16 MHz in fine steps, and measure transmission spectra and photon echoes for each. We predict the spectra and echoes theoretically using the optical combs as input to either a rate equation code or a density matrix code, which calculates the redistribution of populations. We then use the redistributed populations as input to a semiclassical theory using the frequency-dependent dielectric function. The two sets of predictions each give a good, but different account of the photon echoes.

TCD-Profiling Using AVERAGE. A New Technique to Evaluate Transcranial Doppler Ultrasound Flow Spectra of Subjects with Cerebral Small Vessel Disease.

BACKGROUND: There is an unmet need for screening methods to detect and quantify cerebral small vessel disease (SVD). Transcranial Doppler ultrasound (TCD) flow spectra of the larger intracranial arteries probably contain relevant information about the microcirculation. However, it has not yet been possible to exploit this information as a valuable biomarker. METHODS: We developed a technique to generate normalized and averaged flow spectra during middle cerebral artery Doppler ultrasound examinations. Second, acceleration curves were calculated, and the absolute amount of the maximum positive and negative acceleration was calculated. Findings were termed 'TCD-profiling coefficient' (TPC). Validation study: we applied this noninvasive method to 5 young adults for reproducibility. Degenerative microangiopathy study: we also tested this new technique in 30 elderly subjects: 15 free of symptoms but with MRI-verified presence of cerebral SVD, and 15 healthy controls. SVD severity was graded according to a predefined score. Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) study: TPC values of 10 CADASIL patients were compared with those of 10 healthy controls. Pulse wave analysis and local measurements of carotid stiffness were also performed. CADASIL patients were tested for cognitive impairment with the Montreal Cognitive Assessment scale. White matter and basal ganglia lesions in their cerebral MRI were evaluated according to the Wahlund score. RESULTS: Validation study: the technique delivered reproducible results. Degenerative microangiopathy study: patients with SVD had significantly larger TPCs compared with controls (SVD: 2,132; IQR 1,960-2,343%/s vs. CONTROLS: 1,935; IQR 1,782-2,050%/s, p = 0.01). TPC values of subjects with SVD significantly correlated with SVD severity scores (R = 0.58, n = 15, p < 0.05). CADASIL study: TPC values of CADASIL patients were significantly higher than values of the controls (CADASIL: 2,504; IQR 2,308-2,930%/s vs. controls 2,084; 1,839-2,241%/s, p = 0.008), and also significantly higher than the TPC values of the patients with SVD from the degenerative microangiopathy study (p = 0.007). CADASIL patients had significantly worse cognitive test results than healthy controls. CONCLUSION: TCD-profiling detects impairment of the cerebral microcirculatory state. The suitability of the TCD-profiling for the evaluation of cerebral microangiopathy was confirmed.

Supraventricular premature beats and short atrial runs predict atrial fibrillation in continuously monitored patients with cryptogenic stroke.

BACKGROUND AND PURPOSE: Supraventricular premature beats (SPBs) may help to assess the risk of atrial fibrillation (AF) in patients with cryptogenic stroke and therefore guide therapy. METHODS: An internal loop recorder was implanted in consecutive patients with acute cryptogenic stroke. The occurrence and quantity of SPBs and short supraventricular runs (SVRs) in 24-hour ECG in patients with and without future AF were analyzed. We evaluated the relative risk of the upper quartile of SPB and SVR patients against the remainder and used binary logistic regression to evaluate a possible independent influence of SPBs and SVRs on AF occurrence. RESULTS: Twelve of 70 included patients (mean age, 59±13 years) experienced development of AF during a mean monitoring duration of 536±212 days. Patients with AF had a median of 22.8 SPBs/h versus 1.2 SPBs/h (P<0.0001) in patients without AF and a median of 0.7 SVRs/h (AF) versus 0 SVR/h (non-AF). Patients in the upper quartile of SPBs (>14.1/h) and SVRs (>0.2/h) demonstrated a relative risk of 4.0 (95% confidence interval, 1.1-14.6; P=0.04) and 6.9 (95% confidence interval, 1.8-26.7; P=0.005) for future AF, respectively. In binary logistic regression, SPBs (P=0.02) and SVRs (P=0.05) remained significant independent predictors for occurrence of AF. CONCLUSIONS: Numerous SPBs and SVRs demonstrated a high risk for future AF in patients with cryptogenic stroke.

Modified phased radiofrequency ablation of atrial fibrillation reduces the number of cerebral microembolic signals.

AIMS: Phased radiofrequency (RF) ablation for atrial fibrillation is associated with an increased number of silent cerebral lesions on magnetic resonance imaging and cerebral microembolic signals (MESs) on transcranial Doppler ultrasound imaging compared with irrigated RF. The increased rate of embolic events may be due to a specific electrical interference of ablation electrodes attributed to the catheter design. The purpose of this study was to elucidate the effect of deactivating the culprit electrodes on cerebral MESs. METHODS AND RESULTS: Twenty-nine consecutive patients (60 ± 11 years, 10 female) underwent their first pulmonary vein isolation using phased RF energy. Electrode pairs 1 or 5 were deactivated to avoid electrical interference between electrodes 1 and 10 ('modified'). Detection of MESs by transcranial Doppler ultrasound was performed throughout the procedure to assess cerebral microembolism. Results were compared with the numbers of MESs in 31 patients ablated using all available electrodes ('conventional') and to 30 patients undergoing irrigated RF ablation of a previous randomized study. Ablation with 'modified' phased RF was associated with a marked decrease in MESs when compared with 'conventional' phased RF (566 ± 332 vs. 1530 ± 980; P < 0.001). This difference was mainly triggered by the reduction of MES during delivery of phased RF energy, resulting in MES numbers comparable to irrigated RF ablation (646 ± 449; P = 0.7). Total procedure duration as well as time of RF delivery was comparable between phased RF groups. Both times, however, were significantly shorter compared with the irrigated RF group (123 ± 28 vs. 195 ± 38; 15 ± 4 vs. 30 ± 9; P < 0.001, respectively). CONCLUSION: Pulmonary vein isolation with 'modified' phased RF is associated with a decreased number of cerebral microembolism especially during the delivery of ablation impulses, supporting the significance of electrical interference between ablation electrodes 1 and 10. Deactivation of electrode pairs 1 or 5 might increase the safety of this approach without an increase in procedure duration or RF delivery time.

Occult atrial fibrillation in cryptogenic stroke: detection by 7-day electrocardiogram versus implantable cardiac monitors.

BACKGROUND AND PURPOSE: A significant number of patients with cryptogenic stroke suffer from intermittent atrial fibrillation (iAF) which was not detected during the standard diagnostic procedures. We investigated whether implantation of an insertable cardiac monitor (ICM) is feasible in patients with cryptogenic stroke, and compared the iAF detection rate of the ICM with 7-day Holter monitoring. METHODS: Sixty patients (median age 63; interquartile range, 48.5-72 years) with acute cryptogenic stroke were included. ICM was implanted 13 days (interquartile range; 10-65 days) after the qualifying event. Seven-day Holter was performed after the ICM was implanted. RESULTS: The iAF was detected by the ICM in 10 patients (17%; 95% CI, 7% to 26%). Only 1 patient (1.7%; 95% CI, 0% to 5%) had iAF during 7-day Holter monitoring as well (P=0.0077). Episodes of iAF lasting 2 minutes or more were detected 64 (range, 1-556) days after implantation. There were no recurrent strokes during the observation period. The implantation procedure was well tolerated with no adverse events; the daily data transmission protocol was easy to handle by the patients. CONCLUSIONS: ICM implantation for the detection of iAF during outpatient follow-up is feasible in patients with cryptogenic stroke. ICMs offer a much higher diagnostic yield than 7-day Holter monitoring.

Seizures after cerebrovascular events: risk factors and clinical features.

BACKGROUND: Epileptic seizures are well known sequelae of patients with stroke but only little is known about the different risk factors and about the influence of the different types of stroke including sinus thrombosis and bleedings on developing such seizures. Further, the association of post-stroke seizures and conventional vascular risk factors has not been evaluated to date. METHODS: We performed a cohort study on a sample of 593 consecutive patients with different types of cerebrovascular events. In 421 patients, sufficient data were obtained in a personal interview over a mean observation period of 30 months. Data regarding the clinical history were recorded from the patients' charts. RESULTS: The total prevalence of epileptic seizures was 11.6%, the total annual risk was 4.6%. We detected the following significant risk factors: younger age at stroke; higher NIH stroke scale score; any coagulopathy. TIA was found significantly less frequent as a cause of seizures as compared to infarction, bleeding, and sinus thrombosis. Patients with bleeding (14.3%) and with sinus thrombosis (16.3%) were significantly more frequent in the seizure group than in the non-seizure group (6.7% and 1.6%, respectively). The location of stroke, including cortical versus subcortical, did not influence the risk of seizures. The majority of patients developed secondary generalized seizures (57.1%). In adjusted analyses, the two major risk factors for post-stroke epilepsy were a higher NIH stroke scale and a sinus thrombosis as the initial cerebrovascular event. Common lifestyle, vascular, and metabolic risk factors of stroke and for dementia were not associated with the development of seizures. CONCLUSIONS: In conclusion, our data show that epileptic seizures occur in particular after major strokes and in sinus thrombosis. Interestingly, conventional vascular risk factors were not associated with the occurrence of post-stroke seizures. Considering the risk for seizures after certain types of cerebrovascular events might help to early identify patients for anticonvulsive treatment. In the future, it should be investigated whether these patients might benefit from pre-emptive anticonvulsant treatment.

Thalamic involvement in patients with neurologic impairment due to Shiga toxin 2.

OBJECTIVE: The outbreak of hemolytic-uremic syndrome and diarrhea caused by Shiga toxin-producing Escherichia coli O104:H4 in Germany during May to July 2011 involved severe and characteristic neurologic manifestations with a strong female preponderance. Owing to these observations, we designed a series of experimental studies to evaluate the underlying mechanism of action of this clinical picture. METHODS: A magnetic resonance imaging and electroencephalographic study of patients was performed to evaluate the clinical picture in detail. Thereafter, combinations of different experimental settings, including electrophysiological and histological analyses, as well as calcium imaging in brain slices of rats, were conducted. RESULTS: We report on 7 female patients with neurologic symptoms and signs including bilateral thalamic lesions and encephalopathic changes indicative of a predominant involvement of the thalamus. Experimental studies in rats revealed an enhanced expression of the Shiga toxin receptor globotriaosylceramide on thalamic neurons in female rats as compared to other brain regions in the same rats and to male animals. Incubation of brain slices with Shiga toxin 2 evoked a strong membrane depolarization and intracellular calcium accumulation in neurons, associated with neuronal apoptosis, predominantly in the thalamic area. INTERPRETATION: These findings suggest that the direct cytotoxic effect of Shiga toxin 2 in the thalamus might contribute to the pathophysiology of neuronal complications in hemolytic-uremic syndrome.

Septic cavernous sinus thrombosis complicated by occlusion of the internal carotid artery and multiple embolic strokes after surgery of an anorectal abscess: a clinical chameleon.

BACKGROUND: Septic thrombosis of the cavernous sinus (CST) is a rare and potentially life-threatening condition mostly caused by facial or ear, nose, and throat infections. Anatomic structures in vicinity of the cavernous sinus are thereby susceptible to inflammatory damage. In particular nervous system structures are almost regularly affected; however, only few authors reported severe involvement of the internal carotid artery (ICA). CASE PRESENTATION: We present an atypical clinical course of CST in a 61-year-old male diabetic patient caused by a distant focus of inflammation. Septic CST after surgical treatment of an anorectal abscess was complicated by occlusion of the ICA and multiple embolic strokes. The diagnosis was established by magnetic resonance imaging scan, symptoms resolved after antibiotic therapy and heparin anticoagulation. CONCLUSIONS: The presented case and review of literature emphasizes the variability of signs and clinical course of CST, a frequent cause of delayed diagnosis. Especially in immunocompromised patients, the primary source of CST may be a distant inflammatory focus with nonspecific and subacute symptoms. Septic CST can be a rare cause of ischemic stroke when complicated by ICA occlusion because of septic arteritis. Expedited diagnostic workup is necessary and rests upon radiologic investigations.

Predictors of dependency on nursing care after stroke: results from the Dortmund and Münster stroke registry.

BACKGROUND: The long-term effects of stroke have been inadequately studied. We identified social and clinical factors that were associated with application for insurance payments for long-term care within 3.6 years after stroke. METHODS: In a quality-assurance project called "Stroke Northwest Germany," information was obtained from 2286 stroke patients on their socio-demographic background, type of stroke, comorbidities, and degree of physical impairment during their hospital stay, as measured on the Rankin Scale, the Barthel Index, and the Neurological Symptom Scale. We used logistic regression models to identify possible associations between these factors and application for insurance payments for long-term care within 3.6 years after stroke. We developed an appropriate prognostic model by means of backward selection. RESULTS: 734 (32.1%) of the patients participated in follow-up and reported whether they had applied for insurance payments for long-term care. 22.5% had submitted an application. The rate of application was positively correlated with age, female sex, the number of comorbidities and complications during hospitalization, and the degree of physical impairment. CONCLUSION: Stroke has major long-term effects. The probability that a stroke patient will apply for insurance payments for long-term care is a function of the patient's age, sex, previous stroke history, and physical impairment as measured on the Rankin Scale and the Barthel Index.

Heart rate monitoring on the stroke unit. What does heart beat tell about prognosis? An observational study.

BACKGROUND: Guidelines recommend maintaining the heart rate (HR) of acute stroke patients within physiological limits; data on the frequency and predictors of significant deviations from these limits are scarce. METHODS: Demographical data, stroke risk factors, NIH stroke scale score, lesion size and location, and ECG parameters were prospectively assessed in 256 patients with ischemic stroke. Patients were continuously monitored for at least 24 hours on a certified stroke unit. Tachycardia (HR ≥ 120 bpm) and bradycardia (HR <45 bpm) and cardiac rhythm (sinus rhythm or atrial fibrillation) were documented. We investigated the influence of risk factors on HR disturbances and their respective influence on dependence (modified Rankin Scale ≥ 3 after three months) and mortality. RESULTS: HR ≥ 120 bpm occurred in 39 patients (15%). Stroke severity (larger lesion size/higher NIHSS-score on admission), atrial fibrillation and HR on admission predicted its occurrence. HR <45 bpm occurred in 12 patients (5%) and was predicted by lower HR on admission. Neither HR ≥ 120 nor HR <45 bpm independently predicted poor outcome at three moths. Stroke location had no effect on the occurrence of HR violations. Clinical severity and age remained the only consistent predictors of poor outcome. CONCLUSIONS: Significant tachycardia and bradycardia are frequent phenomena in acute stroke; however they do not independently predict clinical course or outcome. Continuous monitoring allows detecting rhythm disturbances in stroke patients and allows deciding whether urgent medical treatment is necessary.

Hereditary and non-hereditary microangiopathies in the young. An up-date.

In recent years, a considerable number of new sporadic or hereditary small artery diseases of the brain have been detected which preferably occur in younger age, below 45 years. Cerebral microangiopathies constitute an appreciable portion of all strokes. In middle aged patients, hereditary cerebral small vessel diseases have to be separated from sporadic degenerative cerebral microangiopathy which is mainly due to a high vascular risk load. Features of the following disorders and details how to differentiate them, are reviewed here, namely CADASIL, MELAS, AD-RVLC, HEMID, CARASIL, PADMAL, FABRY, COL4A1-related cerebral small vessel diseases and a Portuguese type of autosomal dominant cerebral small vessel disease (SVDB). The symptomatic overlap of the cerebral microangiopathies include also other distinctive non-hereditary diseases like posterior (reversible) encephalopathy and Susac's syndrome which are also described. Some of the microangiopathies described here are not only seen in the young but also in the elderly. The precise diagnosis has direct therapeutic implications in several of these entities. Cerebral microangiopathies cause recurring strokes and diffuse white matter lesions leading to a broad spectrum of gait disturbances and in most of these disorders cognitive impairment or even vascular dementia in the long term. Often, they also involve the eye, the inner ear or the kidney. Several typical imaging findings from illustrative cases are presented. The order in which these diseases are presented here is not dictated by an inner logic principle, because a genetically or pathophysiologically based classification system of all these entities does not exist yet. Some entities are well established and not unusual, whereas others have only been described in a few cases in total.

Activated monocytes capture platelets for heterotypic association in patients with severe carotid artery stenosis.

Inflammation and thrombosis, two processes influencing each other, are involved in the pathogenesis of cerebrovascular disease. We showed that in patients with acute ischaemic stroke circulating platelets are activated and exhausted. To identify whether activated haemostasis might be cause or effect, we investigated the role of leukocyte and platelet activation in patients with severe asymptomatic and symptomatic carotid artery disease. Flow cytometry analysis demonstrated that monocytes from symptomatic (acute stroke aetiology) and asymptomatic patients were highly activated, shown by significantly enhanced presentation of inflammatory markers CD11b and thrombospondin-1 (TSP-1) on the surface. Both correlated positively with monocyte-platelet association rate. However, increased monocyte activation and elevated levels of monocyte-platelet associates in asymptomatic patients were restricted to patients with echo-lucent plaques, providing a close link between monocyte activation and plaque morphology. Circulating single as well as monocyte-bound platelets from symptomatic patients showed significantly enhanced surface expression of P-selectin and TSP-1, whereas platelets from asymptomatic patients were not significantly activated. These results indicate that monocytes activated by inflammation rather than platelets might be the candidates to initiate platelet-monocyte rosetting during the pathogenesis of atherothrombotic cerebral ischaemia and that haemostasis might be activated secondarily by the first occurring inflammation.

Correlations between the atherosclerotic changes of femoral, carotid and coronary arteries: a post mortem study.

OBJECTIVE: To compare the severity of atherosclerosis in the carotid, coronary and femoral arteries in autopsy findings of stroke patients. METHODS AND RESULTS: 40 patients (age: 75.2 (12.3) years, 21 men, 19 women) were investigated, who died of ischemic stroke. Carotid, femoral and coronary arteries were removed and cut into slices. Atherosclerotic changes were scored and compared. The severity of atherosclerotic changes of the common carotid artery did not correlate with any other arteries. Atherosclerotic parameters of the internal carotid artery correlated with those of the deep femoral and common femoral arteries (r=0.457-0.459; P=0.022-0.028 respectively). We found significant correlations between the deep femoral artery and left anterior descendent coronary arteries (r=0.513; P=0.012). External carotid artery correlated with both the left anterior descendent coronary and deep femoral arteries (r=0.458-0.473 and P=0.028-0.017 respectively). CONCLUSIONS: The severity of atherosclerosis in the external carotid arteries and/or the femoral arteries showed a stronger correlation with the atherosclerosis in the coronaries than that of the common carotid arteries.

Fiberoptic endoscopic Dysphagia severity scale predicts outcome after acute stroke.

BACKGROUND AND PURPOSE: Fiberoptic endoscopic evaluation of swallowing (FEES) is a suitable method for dysphagia assessment after acute stroke. Recently, we developed the fiberoptic endoscopic dysphagia severity scale (FEDSS) for acute stroke patients, grading dysphagia into 6 severity codes (1 to 6; 1 being best). The purpose of this study was to investigate the impact of the FEDSS as a predictor of outcomes at 3 months and intermediate complications during acute treatment. METHODS: A total of 153 consecutive first-ever acute stroke patients were enrolled. Dysphagia was classified according to the FEDSS, assessed within 24 h after admission. Intermediate outcomes were pneumonia and endotracheal intubation. Functional outcome was measured by the modified Rankin Scale (mRS) at 3 months. Multivariate regression analysis was used to identify whether the FEDSS was an independent predictor of outcome and intercurrent complications. Analyses were adjusted for sex, age and National Institutes of Health Stroke Scale (NIH-SS) on admission. RESULTS: The FEDSS was found to predict the mRS at 3 months as well as but independent from the NIH-SS. For each additional point on the FEDSS, the likelihood of dependency at 3 months (mRS > or = 3) raised by approximately 50%. Each increase of 1 point on the FEDSS conferred a more than 2-fold increased chance of developing pneumonia. The odds for the necessity of endotracheal intubation raised by a factor of nearly 2.5 with each additional point on the FEDSS. CONCLUSIONS: The FEDSS strongly and independently predicts outcome and intercurrent complications after acute stroke. Thus, a baseline FEES examination provides valuable prognostic information for the treatment of acute stroke patients.

Blood pressure threshold violations in the first 24 hours after admission for acute stroke: frequency, timing, predictors, and impact on clinical outcome.

BACKGROUND AND PURPOSE: Admission blood pressure (BP) and significant decreases in BP after acute stroke have been correlated with outcome. Few data are available on the impact of extreme values at any time point within the first 24 hours. METHODS: BP was measured hourly for 24 hours in 325 consecutive patients with acute ischemic stroke. Predefined endpoints were systolic BP >or=200, diastolic BP >or=110, or systolic BP <100 mm Hg during the first 24 hours, and significant systolic BP decreases by >26 mm Hg within 4 hours after admission. Multiple logistic regression analysis identified independent predictors of each end point and determined the impact on dependency at 3 months defined as modified Rankin scale score >or=3. RESULTS: Upper threshold violations occurred in 70% of cases during the admission process, and more frequently in patients arriving early after stroke; 30% of cases exhibited such values at a later time point. History of hypertension (P<0.01) and higher NIHSS on admission (P<0.05) were independent predictors. Systolic BP <100 mm Hg occurred at random and was associated with younger age (P<0.05). Night time admission was the strongest independent predictor of systolic BP decreases >26 mm Hg (P<0.0001). Diabetes, NIHSS on admission, and age were associated with adverse outcome at 3 months, whereas threshold violations and decreases were not. There was a trend for administration of antihypertensives being associated with poor outcome (P<0.1). CONCLUSIONS: External stimuli, premorbid risk factors, diurnal BP variations, and disease-immanent mechanisms all influence the course of BP after acute stroke. Monitoring should precede any medical BP treatment.

Microembolic signals on transcranial Doppler ultrasound are correlated with platelet activation markers, but not with platelet-leukocyte associates: a study in patients with acute stroke and in patients with asymptomatic carotid stenosis.

BACKGROUND: The in vivo correlates of microembolic signals (MES) are still unknown. Platelet-associates (PA) with monocytes or granulocytes or platelet aggregates only may represent these correlates. METHODS: Thirty patients with asymptomatic carotid stenosis >50% and 16 patients with acute (<4 days) atherothrombotic stroke were investigated. PA, P-selectin and thrombospondin expressions on platelets were assessed by flow cytometry. Soluble P-selectin (sPS) levels were assessed. MES detections were performed by transcranial Doppler sonography for 1 hour. PA, P-selectin and thrombospondin expressions on platelets and sPS levels were compared between MES-positive (MES+) and MES-negative (MES-) patients. RESULTS: Eight patients (27%) with asymptomatic carotid stenosis had 1-26 MES/h. Degree of stenosis was 78 +/- 10% in MES- and 88 +/- 8% in the MES+ (p=0.01). There were no differences in percentages of PA. P-selectin and thrombospondin surface expression was lower in MES+, but this was not significant. sPS levels were higher in MES+ (122 +/- 27 ng/ml versus 80 +/- 25 ng/ml in MES-, p=0.01). Seven (44%) patients with stroke had 1-39 MES/h. There were no differences in percentages of PA. MES+ had higher sPS levels (178 +/- 43 versus 121 +/- 44 ng/ml, p=0.02) and less P-selectin surface expression than MES- (9.0 +/- 3.4 versus 4.5 +/- 1.6%, p=0.004). CONCLUSION: High levels of sPS in MES+ and lower expression of platelet activation markers on platelets' surface suggest shedding of activation markers from the platelets' surface and thus enhanced activation of platelets of MES+ compared with MES-. PA are probably not the clinical correlates of MES, but platelets seem to be the main cellular element of solid cerebral microemboli.

Prevalence and prognostic impact of microembolic signals in arterial sources of embolism. A systematic review of the literature.

OBJECTIVE: To compile available studies using microembolic signal (MES) detection by transcranial Doppler sonography in varying sources of arterial brain embolism. We investigated prevalences of MES and whether MES detection is of proven use for risk stratification. METHOD: Studies reporting prevalences of MES and the risk of cerebral ischemic events were pooled for patients with symptomatic or asymptomatic carotid stenosis, intracranial artery stenosis, cervical artery dissection, and aortic embolism. RESULTS: MES were reported in 43% of 586 patients with symptomatic and in 10% of 1066 patients with asymptomatic carotid stenosis. Presence of one MES indicated an increased risk of future events [odds ratio (OR): 7.5, 95% confidence interval (CI): 3.6-15.4, p<0.0001 for symptomatic, and OR: 13.4, 95% CI: 6.5-27.4, p<0.0001 for asymptomatic disease). MES were reported in 25% of 220 patients with symptomatic vs. 0% of 86 patients with asymptomatic intracranial stenosis (p<0.0001), Of 82 patients with cervical artery dissection presenting with TIA or stroke, 50% had MES compared with 13% of 16 patients with local symptoms (p=0.006), In patients with aortic embolism, patients with plaques >or= 4 mm more frequently had MES compared with patients with smaller plaques (p=0.04), Data were insufficient to reliably predict future events in patients with intracranial stenosis, cervical artery dissection, and aortic embolism. CONCLUSION: MES are a frequent finding in varying sources of arterial brain embolism, MES detection is useful for risk stratification in patients with carotid stenosis.