Ultrasound measurement of the fibrous cap in symptomatic and asymptomatic atheromatous carotid plaques.

BACKGROUND: Fibrous cap thickness (FCT) is an important determinant of atheroma stability. We evaluated the feasibility and potential clinical implications of measuring the FCT of internal carotid artery plaques with a new ultrasound system based on boundary detection by dynamic programming. METHODS AND RESULTS: We assessed agreement between ultrasound-obtained FCT values and those measured histologically in 20 patients (symptomatic [S]=9, asymptomatic [AS]=11) who underwent carotid endarterectomy for stenosing (>70%) carotid atheromas. We subsequently measured in vivo the FCT of 58 stenosing internal carotid artery plaques (S=22, AS=36) in 54 patients. The accuracy in discriminating symptomatic from asymptomatic plaques was assessed by receiver operating characteristic curves for the minimal, mean, and maximal FCT. Decision FCT thresholds that provided the best correct classification rates were identified. Agreement between ultrasound and histology was excellent, and interobserver variability was small. Ultrasound showed that symptomatic atheromas had thinner fibrous caps (S versus AS, median [95% CI]: minimal FCT=0.42 [0.34 to 0.48] versus 0.50 [0.44 to 0.53] mm, P=0.024; mean FCT=0.58 [0.52 to 0.63] versus 0.79 [0.69 to 0.85] mm, P<0.0001; maximal FCT=0.73 [0.66 to 0.92] versus 1.04 [0.94 to 1.20] mm, P<0.0001). Mean FCT measurement demonstrated the best discriminatory accuracy (area under the curve [95% CI]: minimal 0.74 [0.61 to 0.87]; mean 0.88 [0.79 to 0.97]; maximal 0.82 [0.71 to 0.93]). The decision threshold of 0.65 mm (mean FTC) demonstrated the best correct classification rate (82.8%; positive predictive value 75%, negative predictive value 88.2%). CONCLUSIONS: FCT measurement of carotid atheroma with ultrasound is feasible. Discrimination of symptomatic from asymptomatic plaques with mean FCT values is good. Prospective studies should determine whether this ultrasound marker is reliable.

Postcarotid endarterectomy hyperperfusion or reperfusion syndrome.

BACKGROUND AND PURPOSE: Hyperperfusion syndrome (HS) after carotid endarterectomy (CEA) has been related to impaired cerebrovascular autoregulation in a chronically hypoperfused hemisphere. Our aim was to provide new insight into the pathophysiology of the HS using magnetic resonance imaging (MRI) studies with diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI). METHODS: Five out of 388 consecutive patients presented 2 to 7 days after CEA, partial seizures (n=5), focal deficits (n=5), and intracerebral hemorrhage (n=3). In 4 patients, using sequential examinations, we identified vasogenic or cytotoxic edema by DWI; we assessed relative interhemispheric difference (RID) of cerebral blood flow (CBF) by PWI; and we measured middle cerebral artery mean flow velocities (MCA Vm) by transcranial Doppler (TCD). RESULTS: None of the patients presented pathological DWI hyperintensities, consistent with the absence of acute ischemia or cytotoxic edema. In 2 patients, we found an MRI pattern of reversible vasogenic edema similar to that observed in the posterior leukoencephalopathy syndrome. Middle cerebral artery (MCA) mean flow velocities (Vm) were not abnormally increased at any time. PWI documented a 20% to 44% RID of CBF in favor of the ipsilateral to CEA hemisphere. CONCLUSIONS: HS can occur in the presence of moderate relative hyperperfusion of the ipsilateral hemisphere. MCA Vm values may not accurately reflect RID of CBF over the cortical convexity. We suggest that the hemodynamic pathogenetic mechanisms of the HS are more complicated than hitherto believed and that they may be more accurately described by the term "reperfusion syndrome."

Vascular risk factors in the Swiss population.

BACKGROUND AND PURPOSE: Identification of the population at risk of stroke remains the best approach to assess the burden of cardiovascular morbidity and mortality. METHODS: The prevalence of hypertension (HT), hypercholesterolemia (HCh), diabetes mellitus (DM), overweight (OW), obesity (OB), tobacco use (SM), and their combinations was examined in 4,458 Swiss persons (1,741 men and 2,717 women, mean age 57.8 +/- 15 years), who volunteered for the present survey. RESULTS: OW was the most prevalent risk factor (50 %), followed by HT (47%), HCh (33%), SM (13 %) and DM (1.6 %). The proportion of persons without risk factors (RF) was 19.9%, with 1 RF 41.5%, 2 RF 33.8%, 3 RF 4%, and 4 RF 0.9%. OW was more prevalent in men than in women (53% vs. 41%, P=0.02). More men than women aged 41-50 years and 51-60 years had HT (49 % vs. 36%, P=0.01, and 52 % vs. 42%, P=0.02). The prevalence of HCh and DM did not show any sex-related differences. HT, OW and HCh were not only the most common single risk factors, but were also most likely to aggregate with each other. CONCLUSIONS: The majority of Swiss people have one or two vascular risk factors. OW and HT are by far most common and are likely to aggregate with each other. A small modification of these two factors would reduce the incidence of stroke and myocardial infarction significantly.

Controlled contrast transcranial Doppler and arterial blood gas analysis to quantify shunt through patent foramen ovale.

BACKGROUND AND PURPOSE: A right-to-left shunt can be identified by contrast transcranial Doppler ultrasonography (c-TCD) at rest and/or after a Valsalva maneuver (VM) or by arterial blood gas (ABG) measurement. We assessed the influence of controlled strain pressures and durations during VM on the right-to-left passage of microbubbles, on which depends the shunt classification by c-TCD, and correlated it with the right-to-left shunt evaluation by ABG measurements in stroke patients with patent foramen ovale (PFO). METHODS: We evaluated 40 stroke patients with transesophageal echocardiography-documented PFO. The microbubbles were recorded with TCD at rest and after 4 different VM conditions with controlled duration and target strain pressures (duration in seconds and pressure in cm H2O, respectively): V5-20, V10-20, V5-40, and V10-40. The ABG analysis was performed after pure oxygen breathing in 34 patients, and the shunt was calculated as percentage of cardiac output. RESULTS: Among all VM conditions, V5-40 and V10-40 yielded the greatest median number of microbubbles (84 and 95, respectively; P<0.01). A significantly larger number of microbubbles were detected in V5-40 than in V5-20 (P<0.001) and in V10-40 than in V10-20 (P<0.01). ABG was not sensitive enough to detect a shunt in 31 patients. CONCLUSIONS: The increase of VM expiratory pressure magnifies the number of microbubbles irrespective of the strain duration. Because the right-to-left shunt classification in PFO is based on the number of microbubbles, a controlled VM pressure is advised for a reproducible shunt assessment. The ABG measurement is not sensitive enough for shunt assessment in stroke patients with PFO.

Solid or gaseous circulating brain emboli: are they separable by transcranial ultrasound?

High-intensity transient signals (HITS) detected by transcranial Doppler (TCD) ultrasound may correspond to artifacts or to microembolic signals, the latter being either solid or gaseous emboli. The goal of this study was to assess what can be achieved with an automatic signal processing system for artifact/microembolic signals and solid/gas differentiation in different clinical situations. The authors studied 3,428 HITS in vivo in a multicenter study, i.e., 1,608 artifacts in healthy subjects, 649 solid emboli in stroke patients with a carotid stenosis, and 1,171 gaseous emboli in stroke patients with patent foramen ovale. They worked with the dual-gate TCD combined to three types of statistical classifiers: binary decision trees (BDT), artificial neural networks (ANN), and support vector machines (SVM). The sensitivity and specificity to separate artifacts from microembolic signals by BDT reached was 94% and 97%, respectively. For the discrimination between solid and gaseous emboli, the classifier achieved a sensitivity and specificity of 81% and 81% for BDT, 84% and 84% for ANN, and 86% and 86% for SVM, respectively. The current results for artifact elimination and solid/gas differentiation are already useful to extract data for future prospective clinical studies.

Pure superficial posterior cerebral artery territory infarction in The Lausanne Stroke Registry.

OBJECTIVE: To determine the patterns of clinical presentation, lesion topography, and etiology in patients with ischemic stroke limited to the superficial territory of the posterior cerebral artery (s-PCA). METHODS: In the Lausanne Stroke Registry (LSR, 1983-1998), we determined the patterns of clinical presentation, lesion topography and mechanisms of stroke, among 117 patients with s-PCA infarction (s-PCAI) on brain imaging. RESULTS: s-PCAIs accounted for 30.5 % of all PCA territory ischemic strokes. The presumed etiology was embolism in 64 (54.5 %) patients [cardiac in 51 (43.5 %) and arterial in 13 (11 %)], indeterminate in 38 (32 %), PCA atherothrombosis in 4 (3.4 %), migraine in 4 (3.4 %), other rare causes in 4 (3.4 %), and multiple potential sources of embolism in 3 (2.5 %). The clinical findings were hemianopsia in 78 (67 %), quadrantanopsia in 26 (22 %), and bilateral visual field defects in 8 (7 %). Motor, sensory, or sensorimotor deficits were detected in 14 (12 %), 8 (6.8 %), or 8 (6.8 %) patients, respectively. Neuropsychological dysfunction included memory impairment in 20 (17.5 %; with left [L], right [R], or bilateral [B] lesions in 15, 2, or 3 patients, respectively), dysphasia in 17 (14.5 %; L/B: 14/3), dyslexia with dysgraphia in 5 (4 %; L/B: 4/1), dyslexia without dysgraphia in 10 (8.5 %; L/B: 8/2), hallucinations in 12 (10 %; L/R/B: 5/5/2), visual neglect in 11 (9.5 %; L/R: 2/9), visual agnosia in 10 (8.5 %; L/B: 7/3), prosopagnosia in 7 (6 %; R/B: 4/3), and color dysnomia in 6 (5 %; L: 6). CONCLUSIONS: s-PCAIs are uncommon, representing less than a third of all PCA infarctions. Although embolism is the main cause in 60 % of patients, identification of the emboli source is often not possible. In 1/3 of cases, the stroke mechanism cannot be determined. Neuropsychological deficits are frequent if systematically searched for.

Giant cell arteritis as a cause of first-ever stroke.

The aims of this study were to assess how frequently giant cell arteritis (GCA) was a cause of first-ever stroke in 4,086 patients in the Lausanne Stroke Registry and to determine the risk factors, patterns, latency and current therapy at onset in patients with GCA plus stroke. GCA was recognized using the criteria of the American College of Rheumatology. We report on 6 patients (0.15%) with a histologically proven diagnosis of temporal arteritis and clinical and neuroradiological evidence of cerebral ischemia. The CT and MRI scans showed lacunar infarction in 3 patients, territorial infarction in 2 and were normal in 1. Stroke latency ranged from 0 to 2 months. All patients suffered from headache. We conclude that stroke is a rare, but dangerous, complication of GCA and that a combination of antiplatelet drugs and corticosteroids may be advisable for preventing stroke occurrence.

Trends in risk factors, patterns and causes in hospitalized strokes over 25 years: The Lausanne Stroke Registry.

BACKGROUND AND OBJECTIVE: The Lausanne Stroke Registry includes, from 1979, all patients admitted to the department of Neurology of the Lausanne University Hospital with the diagnosis of first clinical stroke. Using the Lausanne Stroke Registry, we aimed to determine trends in risk factors, causes, localization and inhospital mortality over 25 years in hospitalized stroke patients. METHODS: We assessed temporal trends in stroke patients characteristics through the following consecutive periods: 1979-1987, 1988-1995 and 1996-2003. Age-adjusted cardiovascular risk factors, etiologies, stroke localizations and mortality were compared between the three periods. RESULTS: Overall, 5,759 patients were included. Age was significantly different among the analyzed periods (p < 0.001), showing an increment in older patients throughout time. After adjustment for age, hypercholesterolemia increased (p < 0.001), as opposed to cigarette smoking (p < 0.001), hypertension (p < 0.001) and diabetes and hyperglycemia (p < 0.001). In patients with ischemic strokes, there were significant changes in the distribution of causes with an increase in cardioembolic strokes (p < 0.001), and in the localization of strokes with an increase in entire middle cerebral artery (MCA) and posterior circulation strokes together with a decrease in superficial middle cerebral artery stroke (p < 0.001). In patients with hemorrhagic strokes, the thalamic localizations increased, whereas the proportion of striatocapsular hemorrhage decreased (p = 0.022). Except in the older patient group, the mortality rate decreased. CONCLUSIONS: This study shows major trends in the characteristics of stroke patients admitted to a department of neurology over a 25-year time span, which may result from referral biases, development of acute stroke management and possibly from the evolution of cerebrovascular risk factors.

Arterial wall imaging.

Not so long ago atherosclerotic plaque formation was considered to be the consequence of a slow, ongoing process leading to artery stenosis or occlusion. Now it is well recognized that arterial narrowing and occlusion develop rapidly after the rupture of an atherosclerotic plaque. Thus, the assessment of the vulnerability of atheromatous plaques is an important issue in ultrasound of the carotid arteries, and will be discussed in this chapter.

Patent foramen ovale: the never-ending story.

Several uncontrolled studies suggested a relationship between patent foramen ovale (PFO) and stroke. But recent data indicate that previous studies may overestimate the association between PFO and stroke. First, among patients who have had a cryptogenic stroke under treatment (with either warfarin or aspirin), the main data from the French PFO/atrial septal aneurysm (ASA) and PICSS (Patent Foramen Ovale in Cryptogenic Stroke Study), analyzed separately and in combination, indicate that PFO alone does not announce a significantly increased risk of recurrent stroke or death. But a small increase or decrease in risk cannot be excluded by this meta-analysis. Second, the data concerning the association between PFO and ASA are not clear and variable: the French PFO/ASA study found a significantly increased risk of recurrent stroke in patients with cryptogenic stroke and an association between PFO and ASA when treated medically. In contrast, PICSS found no association between the combined PFO-ASA with stroke or death, but the two populations had meaningful differences. Patients in the PICSS were much older than those in the French PFO/ASA study and had more risk factors for stroke, such as hypertension, diabetes, and history of prior stroke. Third, there were inadequate data to conclude about ASA alone. Possible practice recommendations could come from this meta-analysis: the evidence indicates that the risk of recurrent stroke or death is not different for patients with a PFO who underwent cryptogenic stroke compared to patients without a PFO who underwent a cryptogenic stroke under treatment with either aspirin or warfarin. But aspirin is more preferable (300 mg/d). However, it seems that the association between PFO and ASA confers an increased risk of recurrent stroke in medically treated patients who are less than 55 years of age. This subgroup of younger stroke patients may benefit from other treatments, such as the percutaneous closure of PFO or mini-invasive surgery to a lesser extent, but their efficacy and safety are not yet assessed by large randomized trials. However, we must also keep in mind that some stroke patients with PFO are psychologically attached to their PFO and prefer to close it.

[Evaluation of the neurologic risk before cardiovascular surgery]. / Evaluation du risque neurologique avant chirurgie cardiovasculaire.

The risk of neurological adverse outcome after open heart surgery is stable since the late 60's. Only since the early 90's cardiac surgeons have shown an interest in decreasing morbidity due to neurological complications. Etiopathological mechanisms of stroke were better understood and due to huge meta-analysis the role of carotid artery disease in adverse neurological outcome was progressively better circumvented. Discovering preoperative markers of neurological hasard is of an uppermost importance for surgeons. It allows to use peri-operative prophylactic strategies, because for the nervous system "prevention is better than cure".