EmboDop: insufficient automatic microemboli identification.
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Automation↗
Biomedical subjects
Erwin Stolz
Publications and source records attributed to Erwin Stolz.
Conservative medical treatment and intravenous thrombolysis in acute stroke from carotid T occlusion.
BACKGROUND: We aimed to analyse the course of early recanalization and corresponding functional outcome in patients with an acute occlusion of the carotid T who were treated conservatively or underwent intravenous thrombolysis. METHODS: Forty-two patients with an acute occlusion of the carotid T within 6 h were recruited from consecutive admissions to a neurological department participating in the Duplex Sonography in Acute Stroke study. All patients underwent a standardized admission and follow-up procedure. Colour-coded duplex sonography was performed on admission, 30 min after thrombolysis, and at 6 and 24 h after onset of symptoms. Recanalization of the carotid T was classified as complete, partial and absent. Functional outcome was rated with the modified Rankin scale (mRS) at 3 months as favourable (mRS 0-2) or poor (mRS 3-6). RESULTS: Within 6 h, complete or partial recanalization occurred in 1 of 27 patients treated conservatively and in 6 of 15 thrombolysed patients. Intravenous thrombolysis predicted early recanalization also after adjustment for age, sex, cardioembolic stroke aetiology and time to treatment (adjusted odds ratio, OR, 39.7; 95% confidence interval, CI, 2.0-801.7; p = 0.016). An early recanalization was the only selected predictor of a favourable outcome (OR, 13.6; 95% CI, 1.0-179.0; p = 0.047) at regression analysis, and was achieved in 3 thrombolysed patients but in none with conservative medical treatment. CONCLUSIONS: In patients treated conservatively, functional outcome is poor and early recanalization rarely occurs. The latter can be achieved by intravenous thrombolysis with a rate comparable to that found at an intra-arterial approach without major intracranial bleeding complications. Early recanalization is associated with a better functional outcome.
Acute Disease↗
Identification of embolic stroke patterns by diffusion-weighted MRI in clinically defined lacunar stroke syndromes.
BACKGROUND: A number of clinical syndromes describing the presentation of deep brain infarcts are called lacunar syndromes resulting from small vessel occlusion (SVO). To verify the reliability of the clinical diagnosis "lacunar syndrome," the value was investigated with diffusion-weighted MRI (DWI). METHODS AND RESULTS: A total of 73 patients (mean age 66 years; range 35 to 83 years) with sudden onset of a classical lacunar syndrome were enrolled. On the basis of the DWI findings, patients were divided into 3 groups: group 1, single subcortical lesion (<15-mm lesion; 43 patients; 59%); group 2, large (> or =15 mm) or scattered lesions in 1 vascular territory (16 patients; 22%); and group 3, multiple lesions in multiple vascular territories (14 patients; 19%). A stroke mechanism other than SVO could be identified in 17 (23%) patients. Cardiac work-up revealed a cardiac embolic source in 8 patients (11%). Duplex sonography revealed symptomatic stenosis in 9 patients (12%). Based on the work-up information, 29 patients (40%) were found to have a potential cause of stroke other than SVO. A significant correlation with >1 single lesion on DWI-MRI and a clinical proven embolic source was observed (P=0.002). In 9 patients with MRI suspicious for a pathomechanism other than SVO, no embolic source was found. CONCLUSIONS: The use of DWI-MRI improves the accuracy of the subtype diagnosis of stroke. Inaccuracy has to be expected in approximately one third if lacunar diagnosis is based on clinical and computed tomography findings. Most of these "false-positive" cases are attributable to large artery or cardiogenic embolic stroke.
Adult↗
Is heparin treatment the optimal management for cerebral venous thrombosis? Effect of abciximab, recombinant tissue plasminogen activator, and enoxaparin in experimentally induced superior sagittal sinus thrombosis.
BACKGROUND: Based on a newly developed model of reversible superior sagittal sinus (SSS) thrombosis in the rat, we investigated the effect of thrombolytic and anticoagulant treatment on recanalization, brain parenchymal changes, and motor deficits. METHODS: Thrombosis of the SSS was induced by topical application of ferric chloride. Occlusion was confirmed by magnetic resonance angiography (MRA). Six hours after operation, single treatment with 10 mg recombinant tissue plasminogen activator (rtPA)/kg and 6 mg abciximab/kg or subcutaneous injection of 450 IU/kg enoxaparin twice daily was started, each group containing 10 rats. Follow-up MRI with T2- and diffusion-weighted images was performed on the first, second, and seventh postoperative day. RESULTS: Control and enoxaparin-treated animals developed diffuse brain edema without infarction or intracerebral bleeding. This was indicated by an increase of T2 relaxation time and a decrease of the apparent diffusion coefficient in the parasagittal and lateral cortex. In these groups, the degree of recanalization after 7 days was comparable (48% versus 52%). Enoxaparin-treated animals showed significant amelioration of functional deficits. Clinical outcome was best in the abciximab-treated group, with a residual sinus occlusion of 36% after 1 week. Highest recanalization was achieved by lysis with rtPA (85%). CONCLUSIONS: Enoxaparin treatment in rats with cerebral venous thrombosis significantly influences clinical outcome. However, it has no effect on recanalization. GPIIb/IIIa antagonists and rtPA accelerate thrombolysis. They may represent an alternative in treatment of cerebral venous thrombosis.
Abciximab↗
Cerebral venous thrombosis: an all or nothing disease? Prognostic factors and long-term outcome.
BACKGROUND: There is insufficient data on short- and especially long-term prognosis of cerebral venous thrombosis (CVT). METHODS: In 79 consecutive patients, we analyzed factors for acute death and functional outcome at hospital discharge and after 6 months as well as long-term prognosis >/=12 months. Neurological deficits were graded on the National Institute of Health Stroke Scale (NIHSS), functional outcome on the modified Rankin Scale (mRS). Primary outcome was defined as mRS >/= 3 at 6 months, secondary outcomes were death during hospital treatment and number as well as type of complications during follow-up >/=12 months after hospital discharge. Forty-two patients were recruited prospectively, 37 were identified by chart review. Information on outcome was based on neurological examinations at our outpatient clinic. RESULTS: Factors significantly related to acute death were age, the NIHSS on admission, more than two seizures despite antiepileptic treatment, venous infarct, and hemorrhagic transformation of the venous infarct. Primary outcome after 6 months in 74 patients was excellent with 73% of patients reaching a mRS 0-1, 4% a mRS of 2, and 23% a mRS 3-6, including 12 deaths in the acute stage of illness. Factors significantly related to a mRS >/= 3 at 6 months in a logistic regression analysis were age and items 1a-c of the NIHSS on admission related to consciousness. Fifty-eight surviving patients had a follow-up >/= 12 months (median: 31; mean: 52 +/- 61 months). Most frequent complication on long-term follow-up was epilepsy in nine patients and recurrent venous thrombosis in seven patients. CONCLUSIONS: When the acute stage of illness has been survived, CVT has a good prognosis unlike arterial ischemic stroke.
Acute Disease↗
A new model of reversible sinus sagittalis superior thrombosis in the rat: magnetic resonance imaging changes.
OBJECTIVE: The causes of cerebral sinus and vein occlusion and the accompanying parenchymal changes remain largely unexplained. The clinical variability and low incidence of the disease complicate systematic clinical investigations. Animal studies are indispensable; however, existing animal models of sinus thrombosis do not allow for long-term follow-up studies and are not suitable for pharmacological recanalization because sinus thrombosis is induced by ligation and injection of thrombogenic substances and does not resemble sinus thrombosis in humans. METHODS: We induced thrombosis of the superior sagittal sinus (SSS) by careful topical application of ferric chloride onto the SSS of rats, leading to highly reproducible occlusions. Magnetic resonance imaging was performed immediately after initiation of thrombosis and on postoperative Days 1, 2, and 7. Diffusion- and T2-weighted images allowed for calculation of the apparent diffusion coefficient and T2 relaxation time. Vascular status was assessed by venous magnetic resonance angiography. Neurological deficits were assessed with the rotarod test. RESULTS: Seven days after induction of thrombosis, partial recanalization (50.7% of the SSS remaining occluded) was accompanied by a resolution of early generalized changes of the apparent diffusion coefficient and of T2 relaxation time, indicating edema of the entire brain parenchyma. Compared with sham-treated animals, clinical skills in the experimental group improved over time, which was statistically independent from the degree of recanalization. Histopathological analysis revealed no signs of cerebral infarction. CONCLUSION: This is the first animal model of SSS thrombosis that offers the possibility to investigate pathophysiological aspects of the disease as well as the influence of therapy on the nature of disease progression.
Animals↗
Reversible MR imaging abnormalities following cerebral venous thrombosis.
BACKGROUND AND PURPOSE: Although rare, cerebral venous thrombosis (CVT) is being diagnosed more frequently owing to improved imaging techniques. The venous infarcts caused by CVT in 50% of patients are largely reversible and differ from arterial stroke. Our purpose was to study the time-dependent changes of venous infarcts on MR images and to define the variables that influence lesion volume in humans. METHODS: MR images and venous angiograms were evaluated in 15 consecutive patients with venous infarcts due to CVT of sinus, cortical, or internal veins. All patients were treated with intravenous dose-adjusted heparin followed by oral anticoagulation for 12 months. Reduction of signal intensity changes on T1- and T2-weighted images was correlated to the degree of recanalization, age, initial absolute lesion size, and hemorrhage. RESULTS: Within the first 30 days, we found a significant correlation between the volume of the lesion on T1-weighted images and recanalization. However, early recanalization did not influence the final lesion volume after 12 months. Eleven patients showed complete resolution of changes on T1- and T2-weighted images. Age of the patients influenced initial absolute volume of brain damage. CONCLUSION: In venous stroke, even large parenchymal changes can resolve completely independent from recanalization of the thrombosed veins and sinuses. A plausible hypothesis is that venous infarcts largely consist of a persistent edema and that the lesion volume is influenced by the development of collateral veins. However, further investigations are necessary to understand the underlying abnormal mechanisms.
Administration, Oral↗
Complications and pitfalls in rat stroke models for middle cerebral artery occlusion: a comparison between the suture and the macrosphere model using magnetic resonance angiography.
BACKGROUND AND PURPOSE: Investigating focal cerebral ischemia requires animal models that are relevant to human stroke. Complications and side effects are common among these models. The present study describes potential pitfalls in 3 techniques for middle cerebral artery occlusion (MCAO) in rats using magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). METHODS: Rats were subjected to temporary MCAO for 90 minutes using the suture technique (group I; n=10) or to permanent MCAO using the suture technique (group II; n=10) or the macrosphere technique (group III; n=10). Clinical evaluation was performed after 3 hours and 24 hours. After 24 hours, animals underwent MRI and MRA to determine lesion size and the intracranial vascular status. RESULTS: Hemispheric lesion volume was significantly smaller in group I (14.6%) compared with groups II (35.2%; P<0.01) and III (21.3%; P<0.05). Two animals (1 each in group II and III) did not demonstrate neurological deficits and had no lesion on MRI and a patent MCA main stem on MRA. Subarachnoid hemorrhage was detected in 2 animals (1 each in group I and II). MRA indicated a patent MCA main stem in 2 animals (group II), although both rats displayed neurological deficits. Hypothalamic infarction with subsequent pathological hyperthermia was detected in all animals in group II and in 1 rat in group III. CONCLUSIONS: Model failures occurred frequently in all groups. MRI and MRA helps to identify animals that need to be excluded from experimental stroke studies.
Animals↗
Comments on 'computed tomographic parameters predicting fatal outcome in large middle cerebral artery infarction'.
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Humans↗
Diffusion-weighted magnetic resonance imaging and neurobiochemical markers after aortic valve replacement: implications for future neuroprotective trials?
BACKGROUND AND PURPOSE: Cardiac surgery carries a high risk of neurological complications; therefore, these patients would be an appropriate target population for neuroprotective strategies. In this study, we evaluated postoperative diffusion-weighted imaging (DWI) as a potential surrogate marker for brain embolism and its relationship to neurobiochemical markers of brain injury. METHODS: Of a total of 45 consecutive patients undergoing aortic valve replacement, 37 completed preoperative and postoperative MRI. At the time of the MRI studies, serum S100beta and neuron-specific enolase concentrations were determined. Preexisting T2 and postoperative DWI lesion volumes were quantified. All patients had a blinded neurological examination before and after operation. RESULTS: New perioperative DWI lesions were present in 14 patients (38%), of whom only 3 developed focal neurological deficits. Eighteen small lesions were found in the white matter or vascular border zones in all but 2 patients with territorial stroke. The appearance of new DWI lesions correlated with age, pre-existing T2 lesion volume, and postoperative S100beta concentrations on days 2 to 4 after surgery. In a forward stepwise canonical discrimination model, only T2 lesion volume was selected as a relevant variable. CONCLUSIONS: The incidence of postoperative DWI lesions in aortic valve replacement is high, and a suitable marker for neuroprotective trials would be a reduction in the number of such lesions. The volume of preexisting T2 lesions is related to the development of perioperative DWI lesions.
Aged↗
Influence of recanalization on outcome in dural sinus thrombosis: a prospective study.
BACKGROUND AND PURPOSE: Recanalization in dural sinus thrombosis (DST) has been observed previously; however, systematic prospective data are lacking. The influence of recanalization on DST outcome has not yet been thoroughly evaluated. METHODS: Thirty-seven consecutive patients with DST were prospectively examined. Neurological deficits were graded with the National Institutes of Health Stroke Scale (NIHSS) on hospital admission and discharge. Functional outcome was assessed with the modified Rankin Scale (mRS) on hospital discharge and after 12 months. All patients were treated with intravenous heparin in the acute stage of illness, followed by oral anticoagulation for 12 months. Imaging follow-up with MR angiography and, in a few cases, with CT or conventional angiography was performed on hospital discharge and after 6 and 12 months. RESULTS: Twelve-month functional outcome was excellent in 89% of patients with an mRS of 0 or 1. A recanalization rate of 60% was already observed on hospital discharge (22+/-6 days); thereafter, recanalization rates increased insignificantly. Early recanalization was not related to NIHSS score on hospital discharge or an mRS of 0 on discharge or after 12 months. CONCLUSIONS: We found a high frequency of early recanalization but without influence on clinical outcome parameters. Frequent imaging follow-ups in DST are not useful because they provide no information on patient outcome.
Adult↗
Strategies for the reduction of cerebral microembolism during transmyocardial laser revascularization.
BACKGROUND AND OBJECTIVES: During transmyocardial laser revascularization (TMLR), multiple microembolic signals (MES) can be detected in cerebral arteries. We sought to characterize composition and clinical relevance of these MES and to evaluate strategies to reduce cerebral microembolization during TMLR. STUDY DESIGN/MATERIALS AND METHODS: TMLR was performed in pigs. Laser energy was set to 4-10 J (group A) or 80 J (group B). Oxygen concentration was varied between 21 and 100%. MES were recorded in the ophthalmic artery. Brain and spinal cord were investigated histologically after 10 days. RESULTS: More MES could be detected during high- compared to low-energy laser procedures. Ventilation with 100% oxygen reduced the number of MES. No lesions were found on histology. CONCLUSIONS: The number of MES depends on the laser energy. Laser-induces cavitation-effects lead to an additional release of nitrogen bubbles. Thus, the microembolic load can be reduced by ventilation with 100% oxygen and by decreasing the laser energy.
Animals↗
Interferon-beta 1b leads to a short-term increase of soluble but long-term stabilisation of cell surface bound adhesion molecules in multiple sclerosis.
Adhesion molecules (AMs) are believed to regulate the transmigration of blood leukocytes across the blood-brain barrier (BBB), which is an essential step in the pathogenesis of multiple sclerosis (MS). Previous studies have investigated changes of the soluble forms of AM during interferon-beta1b (IFN-beta1b) treatment in MS patients. In this study, we analysed the influence of IFN-beta1b treatment on the cell surface bound forms of the AMs cICAM-1 and cICAM-3 on blood mononuclear cells (MNC). Sixty-eight patients with relapsing-remitting MS were enrolled in this open study; thirty of them were treated with IFN-beta1b. Blood samples were collected every three months over a period of 18 months. The expression levels of cell surface bound forms of AM on blood MNC were measured by two colour flow cytometry analysis. sVCAM-1, sICAM-1 and sICAM-3 were determined by ELISA. We found a short-term induction effect on the serum concentrations of sICAM-1 and sVCAM-1 after three months of IFN-beta1b treatment. The expression levels of cell surface bound AMs on blood MNC remained stable during treatment. Untreated MS patients, however, showed a continuous decrease in the expression of cell surface bound AM expression over 18 months. Stabilisation of the expression of cell surface bound AMs on blood MNC may indicate the beneficial effects of IFN-beta1b therapy in MS patients.
Adult↗
Middle cerebral artery occlusion during MR-imaging: investigation of the hyperacute phase of stroke using a new in-bore occlusion model in rats.
Magnetic resonance imaging (MRI) provides insights into the dynamics of focal cerebral ischemia. Usually, experimental stroke is induced outside the magnet bore, preventing investigators from acquiring pre-ischemic images for later pixel-by-pixel comparisons and from studying the earliest changes in the hyperacute phase of ischemia. Herein, we introduce a new and easy to apply in-bore occlusion protocol based on the intraarterial embolization of ceramic macrospheres. PE-50 tubing, filled with saline and six macrospheres (0.315-0.355 mm in diameter), was placed into the internal carotid artery (ICA) of anesthetized Sprague-Dawley rats. The animals were transferred into an MRI scanner (7.0 T) and baseline diffusion-weighted imaging (DWI) and T2-imaging was performed. Then the macrospheres were injected into the internal artery to occlude the MCA. Post-ischemic DWI and T2-imaging was started immediately thereafter. The apparent diffusion coefficient (ADC) (a marker for cytotoxic brain edema) and T2-relaxation time (a marker for vasogenic brain edema) were determined in the ischemic lesions and compared to the unaffected hemisphere. ADC significantly declined within the first 5-10 min after stroke onset. T2-relaxation time increased as early as at the first T2-imaging time-point (20-35 min after embolization). After 150 min of ischemia, the lesions covered 18.0 +/- 7.4% of the hemispheres. The model failed in one out of nine animals (11%). This model allows MR-imaging from the initial minutes after permanent middle cerebral artery (MCA) occlusion. It does not permit reperfusion. This technique might provide information about the pathophysiological processes in the hyperacute phase of stroke.
Acute Disease↗
Sinus thrombosis after a jump from a small rock and a sneezing attack: minor endothelial trauma as a precipitating factor for cerebral venous thrombosis?
Cerebral venous thrombosis (CVT) associated with minor or trivial head trauma has only been described in a few cases so far. We report two patients who developed CVT after a sudden intracranial pressure increase and head acceleration. A 49-year-old woman jumped from a small rock, 1 m in height, and developed instantaneous occipital headaches. Magnetic resonance imaging (MRI) confirmed confluens sinuum thrombosis. Risk factors consisted of smoking and oral contraceptives. Our second patient, an 18-year-old woman, experienced instantaneous headaches after a sneezing attack. Superior sagittal and right-sided transverse sinus thrombosis were confirmed by venous computed tomography angiography. She took oral contraceptives as an additional risk factor. In about 20% of CVT cases the cause remains unclear. As minor head trauma may not have been recognized during history taking, this may represent a so far under-recognized precipitating factor for CVT.
Adolescent↗
Increased monocyte tissue factor activity in women following cerebral venous thrombosis.
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Adult↗
High-dose corticosteroid treatment is associated with an increased risk of developing cerebral venous thrombosis.
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Anti-Inflammatory Agents↗
A sudden arterial blood pressure decrease is compensated by an increase in intracranial blood volume.
BACKGROUND: A sudden decrease in arterial blood pressure (ABP) will cause the intracranial blood volume (IBV) to rise, despite the fact that arterial cerebral blood flow decreases. The aim of this study was to test the hypothesis that the increase in IBV is caused by a relative decrease of intracranial venous outflow. METHODS AND RESULTS: In 10 healthy volunteers we studied cerebral autoregulation (CA) by causing an ABP drop with bilaterally deflating leg cuffs. Blood flow velocities (BFV) in the middle cerebral artery and the straight sinus were monitored continuously with transcranial Doppler ultrasound, and the ABP with a non-invasive photoplethysmographic method. After transforming all variables in relative changes, the arterio-venous BFV difference was calculated. Allowing for diameter changes of the intracranial vessels of up to 10 %, and assuming a resting averaged cerebral blood flow of 55 to 60 ml per 100 g brain tissue per minute, an IBV increase of 9 to 10 ml could be calculated. CONCLUSIONS: In intact CA, a steep decrease of ABP results in an increase of intracranial blood volume. The transformation of our IBV data by means of the human intracranial pressure-volume relationship results in an excellent agreement with previously reported ICP increases of 10 mmHg. The increase in intracranial blood volume might be of clinical relevance in orthostatic dysregulation by increasing the ischemic tolerance of the brain before cerebral autoregulation becomes effective.
Adaptation, Physiological↗