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While philosophy has been defined as a critical endeavour since Plato, the critical potential of rhetoric has been mostly overlooked. In recent years, critique itself – as a means of enlightenment and emancipation – has come under attack. While there have been various attempts to renew and strengthen critical theory and practice, rhetoric has not yet played a part in these attempts. Addressing this lacuna, the article argues that rhetoric can function as a critical force within philosophy. The rhetorical perspective confronts the claim to rational discourse and universal knowledge with the contingency of philosophical languages, means of representation, and social practices. Moreover, it allows us to think of critique as an activity of a subject that is at the same time constituted and transformed by it. This opens up the possibility of a rhetorical philosophizing that meets its critical standards by taking into account both the conditions of its own speaking and what it must exclude as its ‘other’ in order to function.

Conventional processes like shearing dispose a lack in efficiency and formability to manufacture functional components with a high geometric variety. A possibility to allow the efficient and sustainable manufacturing is the application of innovative forming operations like orbital forming. Thus, a strain-hardened component with a load-adapted thickness profile can be manufactured in a single-stage process. Thereby, the control of the material flow could be identified as major challenge due to the three-dimensional stress and strain state. In order to reduce the parts weight and simultaneously guarantee the same level of performance, conventional steel is substituted by lightweight materials such as precipitation hardenable aluminum alloys. However, new challenges arise due to the reduced formability of aluminum compared to conventional steel. In recent research, the potential of a short-term heat treatment to enlarge the formability could be shown. The presented process locally reduces the materials strength, thus allowing a control of the material flow by the interaction between softened areas and areas, which offer the initial conditions. In this contribution, the influence on the formability of orbital formed components manufactured out of the precipitation hardenable aluminum alloy EN AW 6016 by a local short-term heat treatment is investigated. Different geometry-based heat treatment layouts are applied in order to maximize the thickening on different radial positions. The potential to enhance the formability is evaluated by comparing geometrical and mechanical properties of the components manufactured in the conventional process route and with a previous heat treatment. The analysis of radial cross-sections and the hardness distribution reveals the positive influence of the heat treatment but also points out the geometrical dependency of the effect due to the characteristic material flow in orbital forming.

Nowadays, the manufacturing industry faces opposing challenges like a reduction of carbon dioxide on the one hand and on the other hand an increasing weight due to higher safety standards and additional functions. Concepts like lightweight design and functional integration are essential to ensure a sustainable and individual mobility. Gear systems consist of multi-functional parts with a varying sheet thickness and different geometric elements. Since conventional manufacturing processes like shearing are reaching their limits due to complexity and a lack in efficiency, the application of Tailored Blanks is a promising approach to meet these requirements. Manufactured by orbital forming, these process-adapted blanks dispose a high material efficiency. A tumbling motion of the upper punch enables the material distribution, realizing functional components with different material thickenings. The substitution of steel by aluminum is a common approach to meet the demands of lightweight construction. However, the use of aluminum results in a decreased formability at a constant level of strength. In order to enhance the local forming limits, a short-term heat treatment can be applied, reducing the materials’ strength, whereas the untreated areas still offer the initial properties. To transfer the results of fundamental research in Sheet-Bulk Metal Forming with conventional steel to the use of lightweight material, the precipitation hardenable aluminum alloy EN AW 6016 is investigated in an orbital forming process. Since the formability of aluminum is limited and the material flow during the process is three-dimensional, different heat treatment strategies are applied to a rotational-symmetric Tailored Blank and the resulting components are investigated regarding their geometry and mechanical properties. To increase the geometric complexity with regard to an industrial application, the transferability to a cyclic-symmetric layout is analyzed. To evaluate the potential of the heat treatment, the treated components are compared to Tailored Blanks manufactured without heat treatment.

Background and Purpose— Many patients with acute ischemic stroke are not eligible for thrombolysis or mechanical reperfusion therapies due to contraindications, inaccessible vascular occlusions, late presentation, or large infarct core. Sphenopalatine ganglion (SPG) stimulation to enhance collateral flow and stabilize the blood-brain barrier offers an alternative, potentially more widely deliverable, therapy. Methods— In a randomized, sham-controlled, double-masked trial at 41 centers in 7 countries, patients with anterior circulation ischemic stroke not treated with reperfusion therapies within 24 hours of onset were randomly allocated to active SPG stimulation or sham control. The primary efficacy outcome was improvement beyond expectations on the modified Rankin Scale of global disability at 90 days (sliding dichotomy), assessed in the modified intention-to-treat population. The initial planned sample size was 660 patients, but the trial was stopped early when technical improvements in device placement occurred, so that analysis of accumulated experience could be conducted to inform a successor trial. Results— Among 303 enrolled patients, 253 received at least one active SPG or sham stimulation, constituting the modified intention-to-treat population (153 SPG stimulation and 100 sham control). Age was median 73 years (interquartile range, 64–79), 52.6% were female, deficit severity on the National Institutes of Health Stroke Scale was median 11 (interquartile range, 9–15), and time from last known well median 18.6 hours (interquartile range, 14.5–22.5). For the primary outcome, improved 3-month disability beyond expectations, rates in the SPG versus sham treatment groups were 49.7% versus 40.0%; odds ratio, 1.48 (95% CI, 0.89–2.47); P =0.13. A significant treatment interaction with stroke location (cortical versus noncortical) was noted, P =0.04. In the 87 patients with confirmed cortical involvement, rates of improvement beyond expectations were 50.0% versus 27.0%; odds ratio, 2.70 (95% CI, 1.08–6.73); P =0.03. Similar response patterns were observed for all prespecified secondary efficacy outcomes. No differences in mortality or serious adverse event safety end points were observed. Conclusions— SPG stimulation within 24 hours of onset is safe in acute ischemic stroke. SPG stimulation was not shown to statistically significantly improve 3-month disability above expectations, though favorable outcomes were nominally higher with SPG stimulation. Beneficial effects may distinctively be conferred in patients with confirmed cortical involvement. The results of this study need to be confirmed in a larger pivotal study. Clinical Trial Registration— URL: https://www.clinicaltrials.gov . Unique identifier: NCT03767192.

Due to rising demands regarding the functionality and load-bearing capacity of functional components such as synchronizer rings in gear systems, conventional forming operations are reaching their limits with respect to formability and efficiency. One way to meet these challenges is the application of the innovative process class of sheet-bulk metal forming (SBMF). By applying bulk forming operations to sheet metal, the advantages of both process classes can be combined, thus realizing an optimized part weight and an adapted load-bearing capacity. Different approaches to manufacturing relevant part geometries were presented and evaluated regarding the process properties and applicability. In this contribution, a self-learning engineering workbench was used to provide geometry-based data regarding a novel component geometry with circumferential involute gearing manufactured in an SBMF process combination of deep drawing and upsetting. Within the comprehensive investigations, the mechanical and geometrical properties of the part were analyzed. Moreover, the manufactured components were compared regarding the increased fatigue strength in cyclic load tests. With the gained experimental and numerical data, the workbench was used for the first time to generate the desired component as a CAD model, as well as to derive design guidelines referring to the investigated properties and fatigue behavior.

Background and purpose External counterpulsation improves cerebral perfusion velocity in acute stroke and may stimulate collateral artery growth. However, whether (non-acute) at-risk patients with high-grade carotid artery disease may benefit from counterpulsation needs to be validated. Methods Twenty-eight patients (71 ± 6.5 years, five women) with asymptomatic unilateral chronic severe internal carotid artery stenosis (>70%) or occlusion were randomized to receive 20 min active counterpulsation followed by sham treatment or vice versa. Cerebral blood flow velocity (CBFV) (measured bilaterally by transcranial middle cerebral artery Doppler), tissue oxygenation index (TOI) (measured over the bilateral prefrontal cortex by near-infrared spectroscopy) and cerebral hemodynamic parameters, such as relative pulse slope index (RPSI), were monitored. Results Ipsilateral mean CBFV (ΔVmean +3.5 ± 1.2 cm/s) and tissue oxygenation (ΔTOI +2.86 ± 0.8) increased significantly during active counterpulsation compared to baseline, whilst the sham had little effect (ΔVmean +1.13 ± 1.1 cm/s; ΔTOI +1.25 ± 0.65). On contralateral sides, neither counterpulsation nor sham control had any effect on either parameter. During counterpulsation, early dynamic changes in ΔRPSI of the ipsilateral CBFV signal predicted improved tissue oxygenation during counterpulsation (odds ratio 1.179, 95% confidence interval 1.01-1.51), whilst baseline cerebrovascular reactivity to hypercapnia failed to show an association. Conclusions In patients with high-grade carotid disease, ipsilateral cerebral oxygenation and blood flow velocity are increased by counterpulsation. This is a necessary condition for the stimulation of regenerative collateral artery growth and thus a therapeutic concept for the prevention of cerebral ischaemia. This study provides a rationale for further clinical investigations on the long-term effects of counterpulsation on cerebral hemodynamics and collateral growth.

Background Treatment of individuals with asymptomatic carotid artery stenosis is still handled controversially. Recommendations for treatment of asymptomatic carotid stenosis with carotid endarterectomy (CEA) are based on trials having recruited patients more than 15 years ago. Registry data indicate that advances in best medical treatment (BMT) may lead to a markedly decreasing risk of stroke in asymptomatic carotid stenosis. The aim of the SPACE-2 trial (ISRCTN78592017) was to compare the stroke preventive effects of BMT alone with that of BMT in combination with CEA or carotid artery stenting (CAS), respectively, in patients with asymptomatic carotid artery stenosis of ≥70% European Carotid Surgery Trial (ECST) criteria. Methods SPACE-2 is a randomized, controlled, multicenter, open study. A major secondary endpoint was the cumulative rate of any stroke (ischemic or hemorrhagic) or death from any cause within 30 days plus an ipsilateral ischemic stroke within one year of follow-up. Safety was assessed as the rate of any stroke and death from any cause within 30 days after CEA or CAS. Protocol changes had to be implemented. The results on the one-year period after treatment are reported. Findings It was planned to enroll 3550 patients. Due to low recruitment, the enrollment of patients was stopped prematurely after randomization of 513 patients in 36 centers to CEA (n = 203), CAS (n = 197), or BMT (n = 113). The one-year rate of the major secondary endpoint did not significantly differ between groups (CEA 2.5%, CAS 3.0%, BMT 0.9%; p = 0.530) as well as rates of any stroke (CEA 3.9%, CAS 4.1%, BMT 0.9%; p = 0.256) and all-cause mortality (CEA 2.5%, CAS 1.0%, BMT 3.5%; p = 0.304). About half of all strokes occurred in the peri-interventional period. Higher albeit statistically non-significant rates of restenosis occurred in the stenting group (CEA 2.0% vs. CAS 5.6%; p = 0.068) without evidence of increased stroke rates. Interpretation The low sample size of this prematurely stopped trial of 513 patients implies that its power is not sufficient to show that CEA or CAS is superior to a modern medical therapy (BMT) in the primary prevention of ischemic stroke in patients with an asymptomatic carotid stenosis up to one year after treatment. Also, no evidence for differences in safety between CAS and CEA during the first year after treatment could be derived. Follow-up will be performed up to five years. Data may be used for pooled analysis with ongoing trials.

To assess the usefulness of transcranial Doppler CO2 reactivity (CO2R) for prediction of ipsilateral ischemic stroke in carotid artery stenosis and occlusion with a meta-analysis of prospective studies based on individual patient data.We searched Medline, Biosis Previews, Science Citation Index, The Cochrane Library, and EMBASE for studies in which patients with severe carotid artery stenosis or occlusion underwent Doppler CO2R testing (inhalation of CO2 or breath-holding) and were prospectively followed for ipsilateral ischemic stroke. Individual data from 754 patients from 9 studies were included. We used percentage cerebral blood flow velocity increase (pCi) during hypercapnia as the primary CO2R measure, and defined impaired reactivity as pCi20% increase.In a multiple regression model, impaired CO2R was independently associated with an increased risk of ipsilateral ischemic stroke (hazard ratio [HR] 3.69; confidence interval [CI] 2.01, 6.77; p0.0001). Risk prediction was similar for recently symptomatic vs asymptomatic patients. Using continuous values of pCi, a significant association between decreasing pCi and increasing risk of ipsilateral stroke was found: HR of 1.64 (95% CI 1.33, 2.02; p0.0001) per 10% decrease in pCi. For patients with asymptomatic internal carotid artery stenosis only (n = 330), a comparable stroke risk prediction was found: increasing HR 1.95 (95% CI 1.26, 3.04; p = 0.003) per 10% decrease in pCi.This analysis supports the usefulness of CO2R in risk prediction for patients with severe carotid artery stenosis or occlusion, both in recently symptomatic and asymptomatic patients. Further studies should evaluate whether treatment strategies in asymptomatic patients based on CO2R could improve patient outcomes.

Introduction: Identifying factors associated with short term outcome following carotid endarterectomy (CEA) is important to improve patient selection. There are limited data assessing 30-day major adverse cardiac and cerebrovascular events (MACCE: stroke, myocardial infarction (MI) and death) in clinical practice. Hypothesis: We hypothesized that patients fulfilling SAPPHIRE high risk (SHR) or exclusion (SEC) criteria contribute to worse outcomes in a real-life cohort. Methods: Patients undergoing CEA at 2 centers between 1998 and 2010 were prospectively entered into a database. Baseline characteristics, comorbidities, SHR and SEC were assessed using Cox regression to determine predictors for the MACCE 30-day endpoint. Results: The analysis included 748 operations, 262 (35%) asymptomatic , 211 (28%) with previous strokes, and 278 (37%) with transient ischemic attacks (TIA). The overall MACCE rate was 6.7%, 5.0% of asymptomatic and 7.6% in symptomatic patients. SEC patients (n=137) had a MACCE rate of 14.7%; after exclusion, the MACCE rate of the remainder dropped to 4.9% (3.5% in asymptomatic and 5.4% in symptomatic patients). Hazard ratio (HR) for SEC was 3.605 (p=0.0001) after adjustment for symptomatic status. SHR patients did not show a significantly increased event rate (HR 1.714, p=0.16). In multivariate analysis diabetes (HR 2.019, p=0.02), symptomatic status (HR 2.015, p=0.049) and prior MI (HR 1.957, p=0.03) showed an independent influence on MACCE. Conclusion: High risk clinical characteristics, as defined by the SAPPHIRE study were not independently associated with 30-day increased risk of MACCE, although exclusion criteria from that study, diabetes, symptomatic status and prior MI were associated with outcomes.

Summary Cerebral autoregulation is particularly challenged in acute ischemic stroke. In this review we summarize the data of our previous studies on autoregulation regarding the effect of rtPA on autoregulation after stroke. A pooled analysis of two studies (45 patients) has shown a worsening of the autoregulatory index Mx between an early (first 48 h) and late (days 5–7) measurement. This increase was more pronounced on affected sides than on unaffected sides. Poor ipsilateral Mx was associated with a greater volume of MCA infarction at a late measurement and related to poor clinical outcome. Overall, autoregulatory impairment tends to increase mainly in large infarction and generalize to the contralateral side during the first days after ischemic stroke. As a limitation, transcranial Doppler sonography does not allow to detect focal areas of dysautoregulation in smaller strokes. To better understand the temporal and spatial dynamics of dysautoregulation in acute stroke in relation to the type and size of infarction, new bedside hemodynamic monitoring techniques (like multi-channel near-infrared spectroscopy) are needed.

The controversy as to whether Doppler ultrasonic methods should play a role in clinical decision-making in the prevention of stroke is attributable to reported disagreement between angiographic and ultrasonic results and the lack of internationally accepted ultrasound criteria for describing the degree of stenosis. Foremost among the explanations for both is the broad scatter of peak systolic velocities in the stenosis, the criterion that has so far received most attention. Grading based on a set of main and additional criteria can overcome diagnostic errors. Morphological measurements (B-mode images and color flow imaging) are the main criteria for low and moderate degrees of stenosis. Increased velocities in the stenosis indicate narrowing, but the appearance of collateral flow and decreased poststenotic flow velocity prove a high degree stenosis (≥70%), additionally allowing the estimation of the hemodynamic effect in the category of high-degree stenosis. Additional criteria refer to the effect of a stenosis on prestenotic flow (common carotid artery), the extent of poststenotic flow disturbances, and derived velocity criteria (diastolic peak velocity and the carotid ratio). This multiparametric approach is intended to increase the reliability and the standard of reporting of ultrasonic results for arteriosclerotic disease of the carotid artery.

Starting from a pragmatist point of view the paper dismisses the argument that ethical conduct is always based on knowledge of justifying and applying rules. In a first section I show that Plato and Kant already claimed that the originality of the ethical can’t be represented as either propositional knowledge or a norm, but is instead given to us in a way that is never fully available for our rational grasp. In a second section, I will address the ethical conclusions James and Dewey draw from the fact that ethical demands can’t be translated into forms of knowledge. In a third section, I conclude with an argument for the originality of the ethical based on the thoughts of Stanley Cavell, stating that it is always something more than a mere competence in the sense of a knowledge of rules.

Background and Purpose— We hypothesized that for the prediction or exclusion of aortic thrombi or plaques ≥4 mm, the combination of intima-media thickness (IMT) and distensibility (DC) of the common carotid arteries would be superior to the measurement of IMT alone. Methods— We prospectively included 208 stroke patients (mean age, 60 years) undergoing transesophageal echocardiography for screening of aortic plaques. IMT and DC were determined by ultrasound, and DC was quantified by measuring blood pressure and the common carotid arteries diameter change on M-mode ultrasound during the cardiac cycle. Results— Negative predictive values of IMT −3 /kPa for the exclusion of aortic atheroma ≥4 mm were similar (92.0% and 91.7%, respectively). However, negative predictive values increased to 98.2% and to 100.0% for the exclusion of aortic thrombi when both parameters were combined. Positive predictive values of IMT ≥0.9 mm and DC Conclusions— Our findings suggest that IMT and DC represent different vessel wall properties and that measuring both parameters provides optimized characterization of carotid atherosclerosis. Combining IMT and DC increases the predictive power of carotid ultrasound, making transesophageal echocardiography dispensable for assessment of the aorta for those with normal carotid arteries and indispensable for those patients with carotid atherosclerosis.

This study investigated (a) the hypothesis that stroke patients with aortic atheroma would show comparable atherosclerotic changes in the carotid arteries, which are easily accessible for ultrasound evaluation and (b) the possibility of carotid duplex sonography as a replacement for transoesophageal echocardiography (TEE) for the exclusion or prediction of relevant aortic plaques.In 301 consecutive patients (mean age 62 years) with acute cerebral ischaemia, two dimensional ultrasound measurements were taken of common carotid artery intima media thickness (IMT) and maximal plaque area (PA) and the local degree of internal carotid artery (ICA) stenosis were determined. Maximal aortic wall thickness (AWT) was assessed by TEE.An IMTor =0.9 mm yielded a negative predictive value (NPV) of 95.8% for exclusion of aortic atheromasor =4 mm and an NPV of 100% for the exclusion of aortic thrombi. However, positive predictive value of IMT0.9 mm was low (29.6%), increasing only slightly in the presence of carotid plaques (33%). Incidence of aortic thrombi was significantly higher withor =50% compared with50% ICA stenosis (11.3% v 3.9%, respectively). IMT and PA correlated moderately with AWT (r = 0.47, r = 0.53, respectively; p0.001). Systolic blood pressure, coronary heart disease and peripheral artery disease, increased IMT, and ICA stenosisor =50% were independently related to AWTor =4 mm.A high NPV of normal carotid ultrasound does not support routine TEE for the exclusion of complex aortic plaques as a high risk source of cerebral embolism. However, in patients with carotid atherosclerosis, particularly in those with ICA stenosisor =50%, TEE should be performed to exclude an additional high risk source for stroke.

Background and Purpose— This study investigates dynamic cerebral autoregulation assessed from spontaneous blood pressure (ABP) and cerebral blood flow velocity (CBFV) fluctuations and its time course in acute ischemic stroke. Methods— Forty patients admitted with acute ischemic stroke in the territory of the middle cerebral artery (MCA) were enrolled. Admission National Institutes of Health Stroke score was 6±4. Study 1 was performed within 22 (±11) hours and study 2 was performed within 134 (±25) hours of ictus. The final analysis comprised 33 and 29 patients for study 1 and study 2, respectively. Twenty-five age- and sex-matched controls were studied. ABP (Finapres method) and CBFV in both MCAs (transcranial Doppler) were recorded over 10 minutes. Correlations between diastolic and mean ABP and CBFV fluctuations were averaged, yielding the correlation coefficient indices (Dx, Mx). Transfer function analysis was applied to obtain phase shift and gain between ABP and CBFV oscillations. Results— No disturbance of autoregulation was indicated by all parameters at study 1. Separate analyses for clinical severity, stroke side, and size did not reveal significant differences for the various autoregulatory indices at study 1 and 2. At study 2, MCA flow velocity was significantly increased on both sides, the autoregulation index Mx was slightly but significantly ( P Conclusions— Dynamic cerebral autoregulation assessed from spontaneous blood pressure fluctuations does not seem to be relevantly disturbed in early minor MCA stroke. At the subacute stage, slight autoregulatory disturbance may be present.

Background and Purpose— Analysis of dynamic cerebral autoregulation (DCA) from spontaneous blood pressure fluctuations might contribute to prognosis of severe internal carotid artery stenosis, but its response to carotid recanalization has not been investigated so far. This study investigates the effect of carotid endarterectomy or stenting on various DCA parameters. Methods— In 58 patients with severe unilateral stenosis undergoing carotid endarterectomy (n=41) or stenting (n=17), cerebral blood flow velocity (CBFV, transcranial Doppler) and arterial blood pressure (ABP, Finapres method) were recorded over 10 minutes before and on average 3 days after carotid recanalization. Nineteen patients were additionally examined after 7 months. Correlations between diastolic and mean ABP and CBFV fluctuations were averaged to form the correlation coefficient indices (diastolic [Dx] and mean values [Mx]). Transfer function parameters (low-frequency phase and high-frequency gain between ABP and CBFV oscillations) were calculated over the same 10 minutes. CO 2 reactivity was assessed via inhalation of 7% CO 2 . Results— Before recanalization, all DCA parameters were clearly impaired ipsilaterally compared with contralateral sides. Phase, Dx, and Mx indicated early normalization of DCA after both endarterectomy and stenting. By multiple regression, the degree of DCA improvement was highly significantly related to the extent of impairment before recanalization. No significant change in DCA was found at follow-up. Ipsilateral gain and CO 2 reactivity increased significantly less after endarterectomy than after stenting ( P Conclusions— Dynamic cerebral dysautoregulation in patients with severe carotid obstruction is readily and completely remedied by carotid recanalization.

Background and Purpose— Estimation of dynamic cerebral autoregulation from spontaneous fluctuations of arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) is an attractive monitoring option for cerebral hemodynamic impairment. We evaluated the correlation coefficient index method in patients with severe obstructive carotid disease and compared it with transfer function analysis (frequency domain approach to cerebral autoregulation) and CO 2 vasomotor reactivity. Methods— In 139 patients with severe unilateral carotid stenosis (≥70%) or occlusion, CBFV (transcranial Doppler) and ABP (Finapres method) were recorded over 10 minutes. Correlations between systolic pressure, diastolic pressure, and mean ABP and CBFV oscillations over 1-minute epochs were averaged over 10 minutes to form the correlation coefficient indexes (Sx, Dx, Mx, respectively). Transfer function parameters (phase shift and gain between ABP and CBFV oscillations) were determined from the entire 10-minute period. CO 2 reactivity was assessed by inhalation of 7% CO 2 . Results— The correlation indexes Dx and Mx were significantly higher ipsilateral to stenosis and increased with degree of stenosis, indicating increasing dependence of CBFV on ABP and thus impairment of cerebral autoregulation. Dx and Mx correlated moderately but highly significantly with transfer function parameters and CO 2 reactivity and showed a good level of agreement in detecting pathological values. Patients with a small variance of the 1-minute source correlations of Dx and Mx showed clearly better correlation values. Transfer function parameters and CO 2 reactivity but not Dx and Mx were significantly poorer in patients with symptomatic stenosis or occlusion. Conclusions— The potential of the correlation coefficient indexes Dx and Mx in detecting hemodynamic impairment in patients with carotid stenosis is comparable to that of transfer function analysis and CO 2 reactivity testing. In future, a combination of various hemodynamic tests might help to identify patients at risk for ischemic events.

Eclampsia is frequently associated with brain edema, cerebral infarction or hemorrhage. Its underlying cerebrovascular pathophysiology is still poorly understood. We examined cerebral autoregulation by a non-invasive multimodal assessment in a 28-year-old primaparous woman with postpartal eclampsia. Transcranial Doppler sonography showed considerably increased cerebral blood flow velocity (CBFV) of all basal cerebral vessels. Magnetic resonance imaging demonstrated multifocal vasogenic brain edema. Using transfer function analysis, a severely decreased phase shift between respiratory-induced 0.1-Hz oscillations of arterial blood pressure and CBFV was observed, indicating substantial disturbance of dynamic cerebral autoregulation (DCA). In contrast, CO2-vasomotor reactivity of the right middle cerebral artery was only slightly reduced. We therefore assume that the cerebral arteriolar dysfunction in eclampsia leads primarily to an impairment of the autoregulatory mechanism that is followed by different degrees of arteriolar vasodilation. Because of its probably high sensitivity to hemodynamic disturbances, assessment of DCA might be of great value in early pre-eclampsia for risk prediction of cerebral arteriopathy and eclampsia. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.

Giant cell arteritis (GCA) is known to affect the extracranial part of the vertebral arteries. Bilateral vertebral artery occlusion (BVAO) is a rare but serious neurologic condition. We report 3 patients with autopsy-proven (2 patients) or clinically diagnosed (1 patient) GCA causing BVAO. A review of the literature concerning BVAO revealed 5 other cases of BVAO resulting from GCA and 110 cases with underlying arteriosclerotic disease. Our 3 patients (mean age, 66 yr; range, 60-78 yr) with BVAO resulting from GCA all had initial severe headache followed by the onset of stepwise progressive, partly side-alternating neurologic deficits due to bilateral infarctions in the vertebrobasilar circulation territory. This course, more accelerated in BVAO due to GCA than in BVAO of arteriosclerotic origin, seems to be a typical, if not particular, clinical syndrome. BVAO was the first clinical manifestation of GCA in 1 of our patients and in 1 published case. From a clinical view, BVAO resulting from GCA differs from BVAO of arteriosclerotic origin by the much higher mortality rate (75% versus 19%, respectively), the presence of headache (100% versus 22%), fever (50% versus 0%), and elevated erythrocyte sedimentation rate (ESR in all GCA cases >45 mm/h; no data in the arteriosclerotic patient group), but not by the neurologic signs themselves. Therapy of BVAO resulting from GCA is purely empiric. In view of the serious prognosis, we propose treatment with intravenous high-dose glucocorticoids and additional immunosuppression with cyclophosphamide; the use of anticoagulation depends on the individual patient's estimated risk-benefit profile. Although BVAO due to GCA is rare, physicians and especially rheumatologists or neurologists should be aware of this entity because of its high mortality in patients without immediate introduction of a high-dose immunosuppressive therapy. Suspicion of GCA should arise in a patient aged over 50 years with no other vascular risk factors suffering from bilateral symptoms of ischemia in the vertebrobasilar territory, with a quickly progressing stepwise course and with headache, fever, or history of myalgia. ESR and temporal artery biopsy should be performed without delay. Early diagnosis of GCA is necessary for immediate initiation of intensive antiinflammatory and immunosuppressive treatment, without which progressive deterioration and systemic involvement are likely to be fatal.

Recent studies were investigated that report spontaneous oscillations of cerebral perfusion in the very low-frequency range (0.01-0.04 Hz), emphasising details of spectral estimation. The effects of different spectral estimation procedures were compared, using simulated and clinical data. It was shown that data detrending, as used in many studies, can lead to an artifactual peak in the very low-frequency region of estimated power spectra, indicating that the peak cannot be taken as evidence of physiological oscillations. A quantitative, reliable method is described that can be used to assess very low-frequency oscillations. Using the method, very low-frequency oscillations were found in ten out of 17 healthy adults measured with transcranial Doppler (average frequency, 0.021 +/- 0.007 Hz, mean +/- SD), confirming earlier findings based on visual inspection of data.

Background and Purpose —Responsiveness to CO 2 is an established test of cerebrovascular reserve capacity. Arterial partial pressure of CO 2 (P co 2 ) and arterial blood pressure (BP) are key parameters for cerebral blood flow. To investigate the interaction between P co 2 and BP, we performed a study with simultaneous measurement of CO 2 and BP during CO 2 reactivity testing with transcranial Doppler sonography. Methods —Eighty-one healthy volunteers, aged 19 to 74 years, underwent examination defined by a protocol with multimodality monitoring of BP, heart rate (HR), P co 2 , and Doppler frequencies (DFs) of the left middle cerebral artery (MCA). Reproducibility was tested in a subgroup of 14 volunteers ≥65 years of age by CO 2 reactivity testing on different days. Results —Increase of P co 2 was accompanied by a parallel increase of mean±SD time values of DF (3.6±1.6%/mm Hg CO 2 ). BP levels were significantly elevated after 60-second hypercapnia (mean values, 0.5±0.55 mm Hg/mm Hg CO 2 ). A significant decrease over time was seen only for pulsatility in DF but not in BP. Analysis of variance and covariance with repeated measures revealed a highly significant effect of CO 2 on MCA Doppler shift. A less-pronounced effect on DF was seen for BP. Correlation analysis showed no significance for CO 2 reactivity, but a significant correlation between test and retest was seen in BP-related CO 2 reactivity. Conclusions —The CO 2 response curve showed the known linear increase of DF. The parallel significant increase in BP most likely results from activation of the central sympathetic nervous system. The poor reproducibility for Doppler CO 2 reactivity is to some extent explainable by variability of BP. CO 2 -induced increases in BP can have relevant influence on MCA Doppler shift and lead to misinterpretation of Doppler CO 2 test results.

Sirs: Spinal subarachnoid hemorrhage (SAH) acounts for less than 1% of SAHs. Cerebral complications are uncommon and moderate in severity. We report on a 30year old woman suffering from severe cerebral vasospasms, without subarachnoid blood in successive cranial CT scans, due to spinal SAH caused by a ruptured solitary spinal aneurysm of unknown etiology. The patient suffered from a graft-versus-host reaction of her transplanted kidney. Under immunosuppression, she developed recurrent pneumonias and a septicemia with unknown germ that were treated by intravenous antibiotics. In the further course, she suddenly presented with headache, back pain and progressive behavioural disturbances. Cranial CT at this time was normal. Three lumbar punctures revealed a hemorrhagic CSF that was considered to be artificially bloody. Because of increasing paraparesis and rectal incontinence, the patient was referred to our clinic one week later. On admission, she was in poor clinical condition with reduced consciousness, no speech production, nuchal rigidity and paraplegia lasting for more than 24 hours. Cranial CT was normal, whereas cranial MRI showed bilateral MCA-infarction on diffusionweighted MRI (Fig. 1A). Spinal MRI revealed a ventrally located intraspinal circular tumour at the level of the twelfth thoracic vertebra with an intradural T1-hyperintensive signal in the thoracolumbar canal (Fig. 1B). Suboccipital puncture yielded a hemorrhagic CSF (2540 cells per ll). Conventional panangiography revealed a solitary aneurysm (8 · 15 mm) originating from the descending branch of the anterior spinal artery at the level of the twelfth thoracic vertebra (Fig. 1C) as well as generalised, severe cerebral vasospasms. Despite immediate triple-Hand nimodipine-therapy, CT 12h later demonstrated large bilateral MCAinfarction, but was still without any cerebral SAH (Fig. 1D). Because of the infavorable prognosis, palliative treatment was carried out until death due to a pneumogenic sepsis 23 days later. To date, 20 cases of spinal SAH due to a rupture of isolated spinal aneurysms have been reported [1–2, 4–16]. Of the eight reported patients with thoracolumbar aneurysms, all had an acute onset of pain in the thoracolumbar region [1, 8, 11, 13, 15]. Three also had paraparesis [1, 8]. Six of the eight patients were treated surgically [8, 11, 13, 15] whilst the other two had a conservative treatment [1]. All patients recovered either without or with minor neurological deficits. The authors found two dissecting aneurysms [8], an inflammation within the vessel wall in two cases [1, 11] and no evident etiology in the other four reports [1, 8, 13, 15]. In our patient, general autopsy did not reveal any underlying systemic (e.g. polyarteriitis nodosa, connective tissue disorder, syphilis), cerebral or further spinal vascular pathology. Since the SAH was related in timing to systemic infection in the context of immunosuppression, the aneurysm may result from a local inflammation. Morphologically, inflammatory aneurysms are characterised by proliferation of the tunica intima and media as well as inflammatory infiltrates. Infectious agents may be detected within the vessel wall [4, 11]. However, the aneurysm in our patient only yielded a prominent fibroblastic proliferation without inflammatory infiltrates (Fig. 2). Additional analysis of blood and CSF samples did not contain any germs and all serological tests were negative. Thus the inflammatory etiology remains speculative. In summary, we present the case of a young woman who suffered from symptomatic cerebral vasospasms due to spinal SAH caused by a ruptured solitary spinal aneurysm. Pathogenesis of cerebral vasospasm is unclear, but is most probably due to a distant inflammatory response caused by the subarachnoid blood [3]. Although there have been a few R. Surges AE M. Schubert AE C. Weiller A. Hetzel AE W.-D. Niesen (&) Dept. of Neurology University Clinics of Freiburg Breisacherstr. 64 79106 Freiburg, Germany Tel.: +49-761/270-5157 Fax: +49-761/270-5328 E-Mail: wolf-dirk.niesen@uniklinikfreiburg.de

To compare the impact of initial corticosteroid treatment on high-resolution MRI and colour-coded duplex sonography (CCDS) findings in patients with GCA (temporal).Sensitivity and specificity of CCDS and high-resolution contrast-enhanced MRI studies of 59 patients with suspected GCA were retrospectively analysed. Patients were grouped according to the duration of steroid treatment before imaging: 0-1 day, 2-4 days and4 days. In 41 patients, imaging results were compared with findings of temporal artery biopsy (TAB).Sixty-one per cent (36/59) of patients were diagnosed with GCA. TAB findings were positive in 59% (24/41). The compared results of TAB sensitivity of CCDS and MRI under steroid treatment of 0-1 day were 92% and 90%, 2-4 days 80% and 78% and4 days 50% and 80%, respectively. The compared results of the final clinical diagnosis sensitivity of CCDS and MRI under steroid treatment of 0-1 day was 88% and 85%, 2-4 days 50% and 64% and4 days 50% and 56%, respectively.Sensitivity of a first-time CCDS or an MRI for detection of GCA rapidly decreases under corticosteroid treatment. Therefore imaging of patients with suspected GCA should be performed as soon as possible, preferably within the first days of treatment.

Objective To compare the diagnostic performance of high-resolution magnetic resonance imaging (MRI) and color-coded duplex sonography (CCDS) in patients with giant cell (temporal) arteritis (GCA). Methods Results of high-resolution MRI and CCDS in 59 patients with suspected GCA were compared with the final clinical diagnosis (based on the American College of Rheumatology GCA criteria and a 6-month followup study). Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated for each method. In 41 of the patients, imaging results were also compared with the findings of a temporal artery (TA) biopsy. Results Thirty-six of the 59 patients (61%) were ultimately diagnosed as having GCA. Sensitivity of high-resolution MRI and CCDS was 69% and 67%, respectively, specificity was 91% and 91%, PPV was 93% and 92%, and NPV was 66% and 64%, respectively. TA biopsy findings were positive in 24 of the 41 biopsied patients (59%). Sensitivity of high-resolution MRI and CCDS compared with TA biopsy was 83% and 79%, respectively, specificity was 71% and 59%, PPV was 80% and 73%, and NPV was 75% and 67%, respectively. The differences between high-resolution MRI and CCDS were not significant. Conclusion The diagnostic power of high-resolution MRI and CCDS in detecting GCA was comparable. Either of these noninvasive techniques may have value in the evaluation of patients with suspected GCA, and decisions regarding which technique to use may depend on the clinical setting.

Knowledge on autoregulation of cerebellar blood flow in humans is scarce. This study investigated whether cerebellar autoregulation dynamics and CO2 reactivity differ from those of the supratentorial circulation. In 56 healthy young adults, transcranial Doppler (TCD) monitoring of the posterior inferior cerebellar artery (PICA) and, simultaneously, of the contralateral middle cerebral artery (MCA) was performed. Autoregulation dynamics were assessed by the correlation coefficient method (indices Dx and Mx) from spontaneous blood pressure fluctuations and by transfer function analysis (phase and gain) from respiratory-induced 0.1 Hz blood pressure oscillations. CO2 reactivity was measured via inhalation of air mixed with 7% CO2. The autoregulatory indices Dx and Mx did not differ between the cerebellar (PICA) and cerebral (MCA) vasculature. Phase and gain, which describe faster aspects of autoregulation, showed slightly better values in the PICA compared with the MCA (higher phase, P = 0.005; lower gain, P = 0.007). Correlation between absolute autoregulation values in the PICA and the MCA was significant ( P < 0.001). The TCD CO2 reactivity was significantly lower in the PICA ( P < 0.001), which could be influenced by an assumed PICA dilation under hypercapnia. In conclusion, dynamic autoregulation in the human cerebellum is well operating and has slightly faster regulatory properties than the anterior cerebral circulation.

The combination of morphologic and hemodynamic information can help in assessing the risk of embolic stroke associated with thrombi and plaques in the descending aorta. For two acute stroke patients, the determination of individual embolic pathways using flow-sensitive four-dimensional (4D) MRI are reported. 3D visualization of local flow patterns, i.e., retrograde flow channels originating at the site of the atheroma, in conjunction with exact plaque localization, suggested potential embolization of high-risk plaques in the descending aorta although they are located downstream from the supraaortic arteries. Our findings indicate that taking plaques of the descending aorta into consideration may help improve the spectrum of pathologies considered as high-risk sources for brain ischemia. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc.

Objectives: To evaluate a new three dimensional (3D) MRI protocol for the reliable detection of aortic high risk plaques compared with transoesophageal echocardiography (TOE) and to test the reliability of additional MRI in stroke of undetermined aetiology. Methods: 74 acute stroke patients were examined by both TOE and MRI at 3 Tesla with special regard to aortic high risk plaques (ie, ⩾4 mm, superimposed thrombi). ECG synchronised pre- and post-contrast T1 weighted 3D imaging (spatial resolution ∼1 mm3) covering the thoracic aorta was employed. In plaques ⩾3 mm, additional two dimensional T2 imaging and time resolved (CINE) imaging sequences were performed. Aetiology of brain ischaemia was classified according to modified TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria. Aortic high risk embolic sources detected by MRI in patients with cryptogenic stroke were evaluated. Results: Differences in maximum aortic wall thickness for TOE and MRI were not statistically significant for all aortic segments. The overall number of high risk plaques detected by MRI (n = 74) was substantially higher compared with TOE (n = 47). Most noticeably, MRI identified aortic high risk pathologies in 8/26 (30.8%) patients with cryptogenic stroke after standard diagnostics, including TOE (n = 2: dissection or thrombus; n = 6: plaques ⩾4 mm). Conclusions: Our results demonstrate the feasibility of this 3D MRI protocol for the reliable detection of aortic high risk plaques in acute stroke patients. Because of improved visualisation of the aortic arch and the detection of additional embolic sources not seen by standard diagnostics, this novel technique may become a valuable tool for future patients with cryptogenic stroke.

Das Von-Hippel-Lindau-Syndrom ist eine hereditare Tumorerkrankung. Die interdisziplinare Versorgung der Patienten ist von zentraler Bedeutung, weil die Erkrankung nicht nur die Augen, sondern zahlreiche weitere Zielorgane betrifft. Klassische Veranderungen sind Hamangioblastome von Kleinhirn, Medulla oblongata und Ruckenmark, Nierenkarzinome, Phaochromozytome, Pankreaszysten und Inselzelltumoren sowie Tumoren des Endolymphsacks des Innenohrs. Das Untersuchungsprogramm umfasst die augenarztliche Untersuchung, MRT von Kopf, Ruckenmark und Abdomen. Jahrliche Kontrollen werden empfohlen. Die Durchfuhrung der Untersuchungen, die die Grundlage einer rechtzeitigen und meist erfolgreichen Therapie darstellen, ist eine organisatorische Herausforderung.

Die Frage nach den Möglichkeitsbedingungen und motivationalen Ressourcen von Demokratie scheint heute aktueller denn je. Der vorliegende Band stellt sich dieser Frage und erkundet Perspektiven einer umfassenden Demokratisierung von Gesellschaft. Die Autoren beziehen sich dabei - teils zustimmend, teils kritisch - auf die Positionen eines radikaldemokratischen Diskurses (E. Laclau, Ch. Mouffe, J. Derrida, J. Rancière et al.), der sich gegenwärtig darum bemüht, das Politische und die Demokratie jenseits der etablierten Pfade klassischer politischer Theorien neu zu denken. Damit verbunden ist das übergreifende Anliegen der Beiträger, das Politische, das als Kraft einer demokratischen Selbstinstituierung von Gesellschaft verstanden wird, gegen die zunehmende Ökonomisierung aller Lebensbereiche zu verteidigen.

Background and Purpose— A recent study showed a dramatic increase in cerebral hemorrhage comprising atypical locations with low-frequency ultrasound–mediated recombinant tissue plasminogen activator–thrombolysis in humans. Here, we provide a possible explanation for this phenomenon by a side effect observed in a study using the similar ultrasound device. Methods— The study was originally undertaken to investigate by transcranial Doppler sonography, positron emission tomography and perfusion MRI whether transcranial application of wide-field low-frequency ultrasound (300 kHz) improves cerebral hemodynamics in patients with cerebral small vessel disease. Results— Showing no clear positive effect on cerebral hemodynamics in 4 patients and on cerebral perfusion (positron emission tomography) in 2 patients, the study has been terminated early because of a remarkable side effect in the first patient (a 62 year-old man) undergoing perfusion-MRI: detection of frontoparietal extravasation of Gadolinium contrast agent (applied during MRI perfusion imaging preinsonation) on MRI immediately postinsonation. Conclusions— Abnormal permeability of the human blood-brain barrier can be induced by wide-field low-frequency insonation. The observed excessive bleeding rate with low-frequency sonothrombolysis might thus be attributable to primary blood-brain barrier disruption by ultrasound.

Background and Purpose— Transesophageal echocardiography (TEE) is the gold standard in detecting high-risk (ie, aortic thrombi) and potential sources (ie, patent foramen ovale [PFO]) of cerebral embolism. We sought to evaluate the additional information and therapeutic impact provided by TEE in stroke patients and to characterize patients in whom TEE is indispensable. Methods— We included 503 consecutive patients (mean age 62.2 years) with acute brain ischemia. Each patient received TEE and the following routine diagnostics: ultrasound of brain supplying arteries, ECG or Holter-ECG, transthoracic echocardiography, and brain imaging (computed tomography or MRI). Stroke etiology was classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. High-risk sources in TEE were: aortic thrombi or plaques ≥4 mm, thrombi in left atrial cavity/left atrial appendage, spontaneous echo contrast, and left atrial flow velocity Results— Stroke etiology was determined by routine diagnostics in 276 of 503 patients (54.9%). Of the remaining 227 patients (undetermined etiology), 212 (93.4%) were candidates for oral anticoagulation (OA). TEE revealed a high-risk source, with indication for OA in 17 of them (8.0%). A potential source leading to OA was found in an additional 48 patients (22.6%). The remaining 147 patients (69.3%) were treated by platelet inhibitors or statins. Conclusions— TEE strongly influenced secondary prevention and led to OA in one third of our patients with stroke of undetermined etiology. TEE is indispensable in all patients being candidates for OA when routine diagnostics cannot clarify stroke etiology.