Risk of acute brain injury related to cerebral microembolism during cardiac catheterization performed by right upper limb arterial access.

BACKGROUND AND PURPOSE: The primary objective of this study was to assess the incidence of new cerebral infarcts related to cardiac catheterization in patients explored through the right transradial approach. METHODS: This prospective study involved 41 consecutive patients with severe aortic valve stenosis. To assess the incidence of cerebral infarction, all patients underwent cerebral diffusion-weighted MRI before and after cardiac catheterization through the right transradial approach. RESULTS: We detected only two patients (4.9%) with new, small, isolated acute cerebral diffusion abnormalities postcatheterization. All patients remained asymptomatic. CONCLUSIONS: New cerebral lesions on diffusion-weighted MRI are infrequent in patients explored through the right transradial approach. Randomized studies are warranted to confirm for potential advantages of transradial approach versus the femoral approach in cardiac catheterization.

Plaque rupture in the carotid artery is localized at the high shear stress region: a case report.

BACKGROUND AND PURPOSE: Cerebrovascular events are related to atherosclerotic disease in the carotid arteries and are frequently caused by rupture of a vulnerable plaque. These ruptures are often observed at the upstream region of the plaque, where the wall shear stress (WSS) is considered to be highest. High WSS is known for its influence on many processes affecting tissue regression. Until now, there have been no serial studies showing the relationship between plaque rupture and WSS. Summary of Case- We investigated a serial MRI data set of a 67-year-old woman with a plaque in the carotid artery at baseline and an ulcer at 10-month follow up. The lumen, plaque components (lipid/necrotic core, intraplaque hemorrhage), and ulcer were segmented and the lumen contours at baseline were used for WSS calculation. Correlation of the change in plaque composition with the WSS at baseline showed that the ulcer was generated exclusively at the high WSS location. CONCLUSIONS: In this serial MRI study, we found plaque ulceration at the high WSS location of a protruding plaque in the carotid artery. Our data suggest that high WSS influences plaque vulnerability and therefore may become a potential parameter for predicting future events.

Angiogenesis and improved cerebral blood flow in the ischemic boundary area detected by MRI after administration of sildenafil to rats with embolic stroke.

To dynamically investigate the long-term response of an ischemic lesion in rat brain to the administration of sildenafil, male Wistar rats subjected to embolic stroke were treated with sildenafil (n=11) or saline (n=10) at a dose of 10 mg/kg administered subcutaneously 24-h after stroke and daily for an additional 6 days. Magnetic resonance images were acquired and functional performance was measured in all animals at 1 day, 2 days and weekly for 6 weeks post-stroke. All rats were sacrificed 6 weeks after stroke and endothelial barrier antigen immunostaining was employed for morphological analysis and quantification of cerebral vessels. Map-ISODATA was computed from T(1), T(2) and T(1sat) maps. ISODATA derived tissue signatures characterize the degree of ischemic injury. Based on the map-ISODATA calculated at 6 weeks, the ischemic lesion for each animal was divided into two specific regions, the ischemic boundary and ischemic core. The temporal profiles of cerebral blood flow (CBF) and tissue signature were retrospectively tracked in these two regions and were compared with histological evaluation and functional outcome. After 1 week of sildenafil treatment, the ischemic lesion exhibited two significantly different regions, with higher CBF level and correspondingly, lower tissue signature value in the boundary region than in the core region. Sildenafil treatment did not significantly reduce the lesion size, but did enhance angiogenesis. Functional performance was significantly increased after sildenafil treatment compared with the control group. Administration of sildenafil to rats with embolic stroke enhances angiogenesis and selectively increases the CBF level in the ischemic boundary, and improves neurological functional recovery compared to saline-treated rats.

Incidence of new brain lesions after carotid stenting with and without cerebral protection.

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) may be a useful tool to evaluate the efficacy of cerebral protection devices in preventing thromboembolic complications during carotid angioplasty and stenting (CAS). The goals of this study were (1) to compare the frequency, number, and size of new DWI lesions after unprotected and protected CAS; and (2) to determine the clinical significance of these lesions. METHODS: DWI was performed immediately before and within 48 hours after unprotected or protected CAS. Clinical outcome measures were stroke and death within 30 days. RESULTS: The proportion of patients with any new ipsilateral DWI lesion (49% versus 67%; P<0.05) as well as the number of new ipsilateral DWI lesions (median=0; interquartile range [IQR]=0 to 3 versus median=1; IQR=0 to 4; P<0.05) were significantly lower after protected (n=139) than unprotected (n=67) CAS. The great majority of these lesions were asymptomatic and less than 10 mm in diameter. Although there were no significant differences in clinical outcome between patients treated and not treated with protection devices (7.5% versus 4.3%, not significant), the number of new DWI lesions was significantly higher in patients who developed a stroke (median=7.5; IQR=1.5 to 17) than in patients who did not (median=0; IQR=1 to 3.25; P<0.01). CONCLUSIONS: The use of cerebral protection devices significantly reduces the incidence of new DWI lesions after CAS of which the majority are asymptomatic and less than 10 mm in diameter. The frequent occurrence of these lesions and their close correlation with the clinical outcome indicates that DWI could become a sensitive surrogate end point in future randomized trials of unprotected versus protected CAS.

Computer-assisted intraaneurysmal thrombus visualization.

OBJECTIVE: Improved visualization of intraaneurysmal thrombi can contribute to understanding their impact on clinical courses and treatments. Digital subtraction angiography (DSA) demonstrates the hemodynamic portion of aneurysm domes and vasculature structures and has been considered by many to be the principal technique used for aneurysm diagnosis. An intraaneurysmal thrombus may be visualized as a filling defect on DSA, but DSA does not reliably indicate the presence of an intraaneurysmal thrombus or its details. Computerized tomography (CT) and magnetic resonance (MR) imaging may have advantages over DSA, particularly because of their capacity to visualize soft tissue. Hence, we investigated the reconstruction of MR and CT images and compared it to DSA for assessment of intraaneurysmal thrombi. METHODS: Thirty-one patients with 34 aneurysms were enrolled. The entire group was examined with DSA. Sixteen cases were also examined with MR imaging; the remaining 15 were examined with CT imaging. Images of intraaneurysmal thrombi were rendered from corresponding MRI and soft tissue scans using CT. Intracranial vessels and aneurysms were defined from MR and CT angiography. Whole images were linked via imaging software for the reconstruction of vasculature structures. Images were superimposed to produce visualizations of thrombi situated in aneurysmal bodies. RESULTS: Reconstruction of the MR and CT images clearly demonstrated the presence and details of intraaneurysmal thrombi in 9 (26.4 %) of 34 aneurysms. DSA detected only 4 (11.7 %) of the cases as a filling defect. Significant differences in thrombus visualization were observed between DSA used alone or in conjunction with either MRA (P = .02) or CTA (P = .04) images. Mean volume of thrombosed aneurysms was 3.2 +/- 0.84 mL (mean +/- SEM) and thrombosis volume was 0.9 +/- 0.31 mL. Aneurysm and nested thrombus volumes were highly correlated (r = 0.987; P < .001). CONCLUSION: Intraaneurysmal thrombi were clearly visualized by computerized MR and CT image reconstruction. MR and CT were superior to DSA alone in demonstrating the presence of intra-aneurysmal thrombi. Computer-assisted 3-D visualization can be invaluable in understanding the shape and volume of intraaneurysmal thrombi, which may contribute to more accurate assessment and effective treatment of aneurysms cases.

Absence of microemboli on transcranial Doppler identifies low-risk patients with asymptomatic carotid stenosis.

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 > or =60% 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 (TCD+). 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%; P<0.0001) 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; P<0.0001). CONCLUSIONS: Our findings indicate that TCD- ACS will not benefit from endarterectomy or stenting unless it can be done with a risk <1%; TCD+ 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.

Can transcranial Doppler discriminate between solid and gaseous microemboli? Assessment of a dual-frequency transducer system.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasound can reliably detect both gaseous and solid cerebral emboli. However, conventional equipment is unable to discriminate between gaseous and solid emboli. This is a major limitation in situations in which the 2 coexist, because they may have very different clinical relevance. Recently, a novel Embo-Dop system, using insonation at 2 ultrasound transducer frequencies, has been developed. An initial study with a small sample size suggested it provided excellent discrimination. We performed a validation study in subjects with embolic signals of known nature. METHODS: Gaseous embolic signals were obtained in 7 patients with known patient foramen ovale by intravenous injection of agitated saline injections. Solid embolic signals were obtained in patients with symptomatic carotid stenosis (N=23). Discrimination of the 2 using the Embo-Dop system dual-frequency system was assessed. It was compared with discrimination using embolic signal maximum intensity with an intensity threshold. RESULTS: One hundred forty-five solid embolic signals were recorded from carotid stenosis patients. Seventy-three were classified as solid and 72 as gaseous by the Embo-Dop system. Six hundred forty-eight gaseous embolic signals were recorded from 7 patients with patent foramen ovale. Six hundred twenty-five were classified as gaseous and 23 as solid. This gave a sensitivity of 50.3% and specificity of 96.5% for detecting solid embolic signals. Discrimination was better than using a simple intensity threshold. CONCLUSIONS: The Embo-Dop dual-frequency system allows better discrimination than a simple intensity threshold but it is not accurate enough for use in clinical or research studies. Further work is needed to develop reliable clinical systems for discrimination of emboli.

Venous thromboses in particular organs.

Although venous thrombosis most often occurs in the return circulation of the legs and pelvis, it may also occur in the veins of several organs and compromise venous return. Thus, the clinician, in any field will regularly be confronted with manifestations of venous thrombosis in particular organs. This review summarizes the pathogenesis and the main clinical features of venous thrombosis in the central retinal vein, the cerebral veins and sinuses of the skull, the renal and the portal veins and the hepatic and mesenteric veins as well as priapism. The principles of treatment are outlined.

The presence of infection-related antiphospholipid antibodies in infective endocarditis determines a major risk factor for embolic events.

OBJECTIVES: The impact of infection-associated antiphospholipid antibodies (APA) on endothelial cell activation, blood coagulation and fibrinolysis was evaluated in patients with infective endocarditis with and without major embolic events. BACKGROUND: An embolic event is a common and severe complication of infective endocarditis. Despite the fact that APAs are known to be associated with infectious diseases, their pathogenic role in infective endocarditis has not been clearly defined. METHODS: The relationship among the occurrence of major embolic events, echocardiographic vegetation size, endothelial cell activation, thrombin generation, fibrinolysis and APA was examined in 91 patients with definite infective endocarditis, including 26 patients with embolic events and 65 control subjects without embolic events. RESULTS: Overall, 14.3% of patients exhibited elevated APA levels. Embolic events occurred more frequently in patients with elevated levels of APA than in patients without (61.5% vs. 23.1%; p = 0.008). Patients with elevated levels of APA showed higher levels of prothrombin-fragment F1 +2 (p = 0.005), plasminogen-activator inhibitor 1 (p = 0.0002), von Willebrand factor (p = 0.002) and lower levels of activated protein C (p = 0.001) than patients with normal levels of APA. Thrombin generation and endothelial cell activation were both positively correlated with levels of APA. The occurrence of elevated APA levels was frequently associated with structural valve abnormalities (p = 0.01) and vegetations >1.3 cm (p = 0.002). CONCLUSIONS: Infection-associated elevated APA levels in patients with infective endocarditis are related to endothelial cell activation, thrombin generation and impairment of fibrinolysis. This may contribute to the increased risk for major embolic events in these patients.

[Headache in patients with cerebral venous thrombosis]. / Céphalées au cours des thromboses veineuses cérébrales.

Headache is the most frequent symptom of cerebral venous thrombosis. They do not have particular characteristics and can mimic other numerous varieties of headache. Frequently associated with other neurological symptoms, such as intracranial hypertension, seizures, focal deficits or disorders of consciousness, they are sometimes isolated, which stresses the need for investigations in all recent and unusual headache.

[Two cases of top of the basilar syndrome with onset seizure].

We reported 2 patients with top of the basilar syndrome manifested by onset seizure. Patient 1 was a 76-year-old man. When he was sleeping, suddenly he gave a loud cry and went into convulsions. So he was brought to our hospital by ambulance. On admission, he had unconsciousness and left hemiplegia. Patient 2 was a 70-year-old man. When he was bathing, he lost his consciousness and brought to our hospital by ambulance. On admission, he had convulsion and tetraplegia. Both patients had convulsions and palsy when they had brain infarctions. Brain diffusion weighted MR image showed high intensity area in bilateral internal thalamus, brainstem and cerebellum and no high intensity area in cerebral cortex. We know well that Todd's palsy is palsy after convulsion, but vertebro-basilar occlusion also shows convulsion and palsy. Therefore attention should be paid in the case of the patients who had convulsion and palsy.

November 1996--premature baby with lethargy and coma.

A premature male baby (28 weeks gestational age) was delivered by Cesarean section and required ventilation for respiratory distress syndrome during the first postnatal week. Four weeks postnatally, he had an episode of transient renal failure followed by lethargy leading to coma. Ultrasound changes were interpreted as intraventricular hemorrhage, grade 2. The baby died 31 days after birth. Autopsy showed bilateral thrombosis of the deep cerebral veins.

Local cerebral blood flow in a rat cortical vein occlusion model.

The symptoms following sinus and vein occlusion observed in patients and experimental animals display a considerable variability that so far remains largely unexplained. In a rat cortical vein occlusion model using a photochemical thrombotic technique, we examined changes in the cerebral venous flow pattern by fluorescence angiography and regional cerebral blood flow (rCBF) and cerebral blood volume fraction (CBVF) by a modern laser Doppler "scanning" technique. Brain damage was assessed histologically. Fluorescence angiographic findings fell into two groups: group A, rats with an altered venous flow pattern after occlusion (n = 12), and group B, rats with interruption of blood flow and/or a growing venous thrombus (n = 5). In addition, sham-operated animals made up group C (n = 5). Extravasation of fluorescein, a massive decrease in rCBF, a short-lasting increase in CBVF, and regional brain damage were typical for group B. In addition, cortical CBF mapping revealed a transient hyperperfusion zone with hyperemia surrounding a hypoperfused ischemic core in group B. A circulation perturbation following venous occlusion appeared near those occluded cerebral veins without sufficient collateral flow. Furthermore, the venous thrombus continued to grow, accompanied by local critical ischemia and severe brain damage. Conversely, 71% of the animals (12 of 17) tolerated occlusion of a solitary vein without major flow disturbances or histological evidence of damage to the CNS (group A).

Changes in the symptoms of neglect induced by changing task strategy.

Six patients with left side unilateral neglect from lesions of the right cerebral hemisphere were tested with verbal and visuospatial crossing-out tasks. The symptoms of neglect were less severe with the visuospatial than with verbal tasks. We hypothesize that changes in the symptoms of neglect were produced because the tasks altered hemispheric arousal.

Evaluation of recent cerebral infarction by computerized tomography.

Twenty patients with cerebral infarction were observed with serial computerized tomographic (CT) scans. Seventy percent of those infarctions showed a mass effect that had disappeared in all patients by the eighth week after the ictus. In 63%, there was enhancement after contrast infusion, with a definite temporal relationship to the day of onset of the neurological deficit. Twenty percent of the patients initially had normal CT scans that became abnormal weeks after the stroke. Radionuclide scans were positive in the patients who showed contrast enhancement, and the area of abnormal uptake correlated well with the area of enhancement. The timing of the performance of the CT scan in relation to the onset of neurological deficit is an important factor to consider when evaluating the stroke syndrome with CT.

Can embolic stroke be diagnosed on the basis of neurologic clinical criteria?

Diagnosis of embolic stroke is based on identification of a source of embolus (SOE) and on neurologic symptoms acknowledged as "clinical criteria." To test the validity of these criteria, we analyzed the symptoms at onset in 193 patients hospitalized after acute cerebral infarction. Patients were grouped according to identification of a cardiac SOE (106 patients), an arterial SOE (38 patients), or no SOE (49 patients). Cross-tabulations demonstrated that only rapidity and loss of consciousness at onset were associated with the presence of a cardiac SOE to a significant degree. Although these symptoms were highly specific for cardiac SOE, they were not sensitive. A distinct clinical neurologic profile from the symptoms and mode of onset was not identified.

Cerebral air embolism. Report of five cases and review of the literature.

We discuss five patients who had cerebral air embolisms. Clinically, these patients had early seizures, focal neurological findings, or failure to awaken from anesthesia. The patients that survived had minimal neurological deficits. We also discuss the pathophysiology of cerebral air embolism and its differentiation from "the bends." The necessity for recognizing this entity early is important in order to administer appropriate therapy.

Lateral medullary syndrome after neck injury.

Several reported cases of brainstem stroke followed neck manipulation or trauma. We describe a 28-year-old man who had a lateral medullary syndrome after cervical hyperextension in an automobile accident. Angiography revealed complete occlusion of the left vertebral artery.

MRI of cerebral vein thrombosis in infancy: a case report.

We diagnosed primary idiopathic cerebral vein thrombosis in an infant by MRI. The relative noninvasiveness of the scan, ease of imaging in multiple planes, and good image resolution suggest that the scan may be useful in this disorder.

Paradoxical cerebral embolism: eight cases.

We evaluated eight patients with possible or probable paradoxical cerebral embolism. One patient had a hemispheric transient ischemic attack; the others had infarcts. Ischemic symptoms followed a Valsalva's maneuver in three cases. Others were linked to placement of a Swan-Ganz catheter, deep venous thrombosis and pulmonary embolism, right atrial myxoma, and use of oral contraceptives. Four had no known predisposing conditions. In six patients, contrast echocardiography showed right-to-left shunting. Cardiac catheterization showed a patent foramen ovale in three patients; one had an atrial septal defect. In the clinical setting of otherwise unexplained cerebral embolism in a young patient, paradoxical cerebral embolism should be considered. Contrast echocardiography is a useful screening test for this purpose.