Editor's Choice - Relevance of Infarct Size, Timing of Surgery, and Peri-operative Management for Non-ischaemic Cerebral Complications After Carotid Endarterectomy.

OBJECTIVE: To assess the incidence of post-operative non-ischaemic cerebral complications as a pivotal outcome parameter with respect to size of cerebral infarction, timing of surgery, and peri-operative management in patients with symptomatic carotid stenosis who underwent carotid endarterectomy (CEA). METHODS: Retrospective analysis of prospectively collected single centre CEA registry data. Consecutive patients with symptomatic carotid stenosis were subjected to standard patch endarterectomy. Brain infarct size was measured from the axial slice of pre-operative computed tomography/magnetic resonance imaging demonstrating the largest infarct dimension and was categorised as large (> 4 cm2), small (≤ 4 cm2), or absent. CEA was performed early (within 14 days) or delayed (15 - 180 days) after the ischaemic event. Peri-operative antiplatelet regimen (none, single, dual) and mean arterial blood pressure during surgery and at post-operative stroke unit monitoring were registered. Non-ischaemic post-operative cerebral complications were recorded comprising haemorrhagic stroke and encephalopathy, i.e., prolonged unconsciousness, delirium, epileptic seizure, or headache. RESULTS: 646 symptomatic patients were enrolled of whom 340 (52.6%) underwent early CEA; 367 patients (56.8%) demonstrated brain infarction corresponding to stenosis induced symptoms which was small in 266 (41.2%) and large in 101 (15.6%). Post-operative non-ischaemic cerebral complications occurred in 12 patients (1.9%; 10 encephalopathies, two haemorrhagic strokes) and were independently associated with large infarcts (adjusted odds ratio [OR] 6.839; 95% confidence interval [CI] 1.699 - 27.534) and median intra-operative mean arterial blood pressure in the upper quartile, i.e., above 120 mmHg (adjusted OR 13.318; 95% CI 2.749 - 64.519). Timing of CEA after the ischaemic event, pre-operative antiplatelet regimen, and post-operative blood pressure were not associated with non-ischaemic cerebral complications. CONCLUSION: Infarct size and unintended high peri-operative blood pressure may increase the risk of non-ischaemic complications at CEA independently of whether performed early or delayed.

Modification of In-Hospital Recommendation and Prescription of Anticoagulants for Secondary Prevention of Stroke after Launch of Direct Oral Anticoagulants and Change of National Guidelines.

INTRODUCTION: Approximately 1 out of 4 stroke patients suffers ischemic stroke secondary to atrial fibrillation (AF). Although indicated, withholding of anticoagulants for secondary prevention is a widespread phenomenon. OBJECTIVE: We examined the longitudinal change of recommendation and prescription of secondary preventive anticoagulation in AF patients in an acute stroke center setting focusing on the impact of the introduction of direct oral anticoagulants (DOACs) and the change of national stroke prevention guidelines. METHODS: Consecutive patients admitted with an acute cerebrovascular ischemic event underwent regular diagnostic work-up. Pseudonymized clinical data were entered into the institution's stroke registry. In those patients with AF, discharge letters were collected and evaluated for temporal trends and affecting factors of recommended and prescribed antithrombotic secondary medication at the time of discharge from hospital. RESULTS: Of 7,175 patients admitted between January 2009 and December 2018, 1,812 (25.3%) suffered stroke caused by AF. Frequency of patients with recommended anticoagulation increased within the observation period from 66.7 to 95.8% (per year; adjusted odds ratio [OR], 1.309; confidence interval [CI], 1.153-1.486). Independently from this time trend, DOAC approval (adjusted OR, 4.026; CI 1.962-8.265) and guideline change (adjusted OR, 2.184; CI, 1.006-4.743) were associated with an increasing frequency of recommendation for anticoagulation. The rate of patients already receiving recommended anticoagulation for secondary prevention at discharge increased from 42.1 to 62.5%. Introduction of DOACs was not associated with this trend, and guideline change was even associated with decreasing frequency of anticoagulated patients at hospital discharge (adjusted OR, 0.641; CI, 0.414-0.991). Fear of early intracerebral bleeding was the most common reason for withholding anticoagulation (37%) at hospital discharge and stayed stable during the observation period. CONCLUSIONS: Changing national guidelines with discard of contraindications for anticoagulation and the introduction of DOACs led to a broader recommendation of oral anticoagulation. However, both, new guidelines and DOACs, were not found to be associated with an increasing percentage of patients discharged from our hospital already on recommended anticoagulant prevention. This might be explained by the decreasing length of hospital stay during the study period and a missing evidence of early bleeding risk of DOACs in patients with acute brain infarction. Evidence-based data to close this therapeutic gap are needed.

Acute symptomatic extracranial internal carotid occlusion - natural course and clinical impact.

Background: To assess the vascular and clinical course of acute symptomatic extracranial internal carotid artery (ICA) occlusion. Patients and methods: Patients with an acute ischemic event in the anterior circulation and corresponding extracranial ICA occlusion at CT angiography and/or color-coded duplex sonography underwent recurrent duplex follow-up for detection of spontaneous recanalization. Stroke recurrence and functional outcome 4.5 months after the ischemic index event assessed by modified Rankin scale served as secondary outcome parameters. Results: 133 patients (91 men, mean age 62.3 years, SD 10.8) demonstrated symptomatic occlusion of the extracranial ICA with open intracranial ICA and open middle cerebral artery and were followed-up for spontaneous recanalization. Twenty-eight recanalized spontaneously, 25 to high-grade focal stenosis within 12 days, revealing an early cumulative recanalization rate of 23 %. Detection of recanalization was independently associated with de novo dual anti-platelet therapy (adjusted odds ratio [OR], 3.24; 95 % confidence interval [CI], 1.34 to 7.80). Ischemic recurrence occurred in 16 patients, of which 10 deemed to be embolic and 5 hemodynamic. Spontaneous ICA recanalization and an exhausted cerebrovascular reserve in the hemisphere distal to the occluded ICA were both independently associated with the occurrence of a recurrent ischemic event at Cox regression. An increasing NIHSS score at admission, a decreasing middle cerebral artery flow velocity and an ischemic recurrence independently predicted poor outcome (modified Rankin scale 3 to 6) in multivariate analysis. Conclusions: Acute symptomatic extracranial ICA occlusion is an unstable condition with frequent spontaneous recanalization to severe stenosis and early embolic stroke recurrence, demanding appropriate prevention especially in those patients with only mild deficit.

Neural correlates of visual motion processing without awareness in patients with striate cortex and pulvinar lesions.

Patients with striate cortex lesions experience visual perception loss in the contralateral visual field. In few patients, however, stimuli within the blind field can lead to unconscious (blindsight) or even conscious perception when the stimuli are moving (Riddoch syndrome). Using functional magnetic resonance imaging (fMRI), we investigated the neural responses elicited by motion stimulation in the sighted and blind visual fields of eight patients with lesions of the striate cortex. Importantly, repeated testing ensured that none of the patients exhibited blindsight or a Riddoch syndrome. Three patients had additional lesions in the ipsilesional pulvinar. For blind visual field stimulation, great care was given that the moving stimulus was precisely presented within the borders of the scotoma. In six of eight patients, the stimulation within the scotoma elicited hemodynamic activity in area human middle temporal (hMT) while no activity was observed within the ipsilateral lesioned area of the striate cortex. One of the two patients in whom no ipsilesional activity was observed had an extensive lesion including massive subcortical damage. The other patient had an additional focal lesion within the lateral inferior pulvinar. Fiber-tracking based on anatomical and functional markers (hMT and Pulvinar) on individual diffusion tensor imaging (DTI) data from each patient revealed the structural integrity of subcortical pathways in all but the patient with the extensive subcortical lesion. These results provide clear evidence for the robustness of direct subcortical pathways from the pulvinar to area hMT in patients with striate cortex lesions and demonstrate that ipsilesional activity in area hMT is completely independent of conscious perception.

Peripheral nerve ultrasound in amyotrophic lateral sclerosis phenotypes.

INTRODUCTION: In this study we sought to determine the cross-sectional area (CSA) of peripheral nerves in patients with distinct subtypes of amyotrophic lateral sclerosis (ALS). METHODS: Ulnar and median nerve ultrasound was performed in 78 ALS patients [classic, n = 21; upper motor neuron dominant (UMND), n = 14; lower motor neuron dominant (LMND), n = 20; bulbar, n = 15; primary lateral sclerosis (PLS), n = 8] and 18 matched healthy controls. RESULTS: Compared with controls, ALS patients had significant, distally pronounced reductions of ulnar CSA (forearm/wrist level) across all disease groups, except for PLS. Median nerve CSA (forearm/wrist level) did not differ between controls and ALS. CONCLUSION: Ulnar nerve ultrasound in ALS subgroups revealed significant differences in distal CSA values, which suggests it has value as a marker of LMN involvement. Its potential was particularly evident in the UMND and PLS groups, which can be hard to separate clinically, yet their accurate separation has major prognostic implications.

Predictors for Adherence to Recommended Anticoagulation after Stroke Unit Discharge in Patients with Atrial Fibrillation.

INTRODUCTION: Non-adherence to recommended secondary preventive anticoagulation in stroke patients with atrial fibrillation (AF) is a common phenomenon although the introduction of direct oral anticoagulants (DOACs) has simplified anticoagulation management for physicians as well as for patients. METHODS: We examined the adherence of secondary preventive anticoagulation in AF patients after re-integration in their social environment 6 to 12 weeks after stroke unit and rehabilitation clinic treatment and analyzed for predictors for adherence and non-adherence. We conducted a telephone survey in consecutive patients treated between January 2013 and December 2021 at our institutional stroke unit with an acute cerebrovascular ischemic event and we analyzed discharge letters of rehabilitation clinics of those patients not anticoagulated at follow-up. All patients had known or newly diagnosed AF and in all we had recommended secondary preventive anticoagulation. RESULTS: Follow-up information about anticoagulant intake could be obtained in 1348 of 1685 patients (80.0%) treated within the study period. Anticoagulation rate was 91.5% with 83.6% of patients receiving DOACs and 7.9% receiving vitamin K antagonists (VKAs). Adherence to recommended anticoagulation was associated with intake of the recommended anticoagulant already at discharge (adjusted OR, 18.357; CI, 9.637 to 34.969), recommendation of a specific DOAC and dose (in contrast to "DOAC" as drug category) (adjusted OR, 2.971; CI, 1.173 to 7.255), a lower modified Rankin Scale at discharge (per point; adjusted OR, 0.813; CI, 0.663 to 0.996), younger age (per year; adjusted odds ratio [OR], 0.951; confidence interval [CI], 0.926 to 0.976), and the absence of peripheral vascular disease (adjusted OR, 0.359; CI, 0.173 to 0.746). In patients already anticoagulated at discharge adherence was 98.5%, irrespective of a patient's age, functional deficit at discharge, and peripheral vascular disease. Avoidable obstacles for non-adherence in patients not on anticoagulants at stroke unit discharge were (1) non-implementation of recommended anticoagulation by rehabilitation physicians predominantly in patients with moderate-severe or severe stroke disability (2.1%), (2) delegation of anticoagulation start from rehabilitation physicians to general practitioners/resident radiologists (1.3%), and (3) rejection of recommended anticoagulation because of patients' severe stroke disability (0.5%). Non-avoidable obstacles were contraindications to anticoagulation (2.1%) and patients' refusal (0.7%). CONCLUSIONS: Commencing drug administration already during stroke unit hospitalization and providing an explanation for the selection of the recommended anticoagulant in discharge letters ensures high adherence at patients' re-integration in their social environment after acute stroke treatment. If drug administration cannot be commenced before discharge, education of rehabilitation physicians by stroke physicians and the involvement of stroke physicians into the post-stroke decision process might hinder avoidable obstacles.

High-Sensitivity Cardiac Troponin T and Cognitive Function Over 12 Months After Stroke-Results of the DEMDAS Study.

BACKGROUND: Subclinical myocardial injury in form of hs-cTn (high-sensitivity cardiac troponin)  levels has been associated with cognitive impairment and imaging markers of cerebral small vessel disease (SVD) in population-based and cardiovascular cohorts. Whether hs-cTn is associated with domain-specific cognitive decline and SVD burden in patients with stroke remains unknown. METHODS AND RESULTS: We analyzed patients with acute stroke without premorbid dementia from the prospective multicenter DEMDAS (DZNE [German Center for Neurodegenerative Disease]-Mechanisms of Dementia after Stroke) study. Patients underwent neuropsychological testing 6 and 12 months after the index event. Test results were classified into 5 cognitive domains (language, memory, executive function, attention, and visuospatial function). SVD markers (lacunes, cerebral microbleeds, white matter hyperintensities, and enlarged perivascular spaces) were assessed on cranial magnetic resonance imaging to constitute a global SVD score. We examined the association between hs-cTnT (hs-cTn T levels) and cognitive domains as well as the global SVD score and individual SVD markers, respectively. Measurement of cognitive and SVD-marker analyses were performed in 385 and 466 patients with available hs-cTnT levels, respectively. In analyses adjusted for demographic characteristics, cardiovascular risk factors, and cognitive status at baseline, higher hs-cTnT was negatively associated with the cognitive domains "attention" up to 12 months of follow-up (beta-coefficient, -0.273 [95% CI, -0.436 to -0.109]) and "executive function" after 12 months. Higher hs-cTnT was associated with the global SVD score (adjusted odds ratio, 1.95 [95% CI, 1.27-3.00]) and the white matter hyperintensities and lacune subscores. CONCLUSIONS: In patients with stroke, hs-cTnT is associated with a higher burden of SVD markers and cognitive function in domains linked to vascular cognitive impairment. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01334749.

Sonography of the median nerve in CMT1A, CMT2A, CMTX, and HNPP.

INTRODUCTION: In this study we compare the ultrasound features in the median nerve in patients with different types of Charcot-Marie-Tooth (CMT) disease and hereditary neuropathies with liability to pressure palsies (HNPP) as a typical entrapment neuropathy. METHODS: Median nerve ultrasound and conduction studies were performed in patients with CMT1A (n = 12), MFN2-associated CMT2A (n = 7), CMTX (n = 5), and HNPP (n = 5), and in controls (n = 28). RESULTS: Median nerve cross-sectional area (CSA) was significantly increased in CMT1A, whereas, in axonal CMT2A, fascicle diameter (FD) was enlarged. CSA correlated with nerve conduction slowing in CMT1A and with axonal loss, as shown by motor and sensory nerve amplitudes in both CMT1A and CMT2A. A relatively low wrist-to-forearm-ratio (WFR <0.8) or a relatively high WFR (>1.8) appeared to be unlikely in MFN2 and Cx32 mutations of CMT2A and CMTX, respectively. CONCLUSION: Differences in CSA, FD, and WFR of the median nerve can be helpful in defining subtypes of hereditary neuropathies.

Assessment of cortical hemodynamics by multichannel near-infrared spectroscopy in steno-occlusive disease of the middle cerebral artery.

BACKGROUND AND PURPOSE: In a pilot study we evaluated near-infrared spectroscopy as to its potential benefit in monitoring patients with steno-occlusive disease of a major cerebral artery for alterations in cortical hemodynamics. METHODS: Cortical maps of time-to-peak (TTP) in 10 patients unilaterally affected by severe stenosis or occlusion of the middle cerebral artery were acquired by multichannel near-infrared spectroscopy after bolus application of indocyanine green. Hemodynamic manifestations were assessed by comparison between affected and unaffected hemisphere and evaluated for common constituents by principal component analysis. In one patient, TTP values were compared with those obtained by dynamic susceptibility contrast imaging. RESULTS: TTP was increased on the affected hemisphere in 9 patients. Mean difference in TTP between hemispheres was 0.44 second (P<0.05) as compared with a mean lateral difference of 0.12 second found in a control group of 10 individuals. In group analysis a significant rise in TTP was found in the distribution of the affected middle cerebral artery, whereas principal component analysis suggests augmentation of hemodynamic effects toward the border zones as a dominant pattern. A linear correlation of 0.61 between TTP values determined by dynamic susceptibility contrast MRI and near-infrared spectroscopy was found to be statistically significant (P<0.001). CONCLUSIONS: Multichannel near-infrared spectroscopy might facilitate detection of disease-related hemodynamic changes as yet only accessible by tomographic imaging modalities. Being indicative for hypoperfusion and collateral flow increased values of TTP, as found to a varying extent in the present patient group, might be of clinical relevance.

Grading carotid stenosis using ultrasonic methods.

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.

Do basophile structures as age dependent phenomenon indicate small vessel wall damage?

Here we demonstrate basophile structures located in the arteriolar wall and being associated with a plasma-protein-leakage. We assume, that the structures indicate blood-brain-barrier-disturbances and degenerative small vessel wall alterations.

Risk of wound hematoma at carotid endarterectomy under dual antiplatelet therapy.

BACKGROUND AND PURPOSE: This study aims to assess perioperative incidence of wound hematoma and bleeding in patients who underwent carotid endarterectomy (CEA) under dual antiplatelet therapy. METHODS: Consecutive patients with initial CEA receiving aspirin, clopidogrel, or a combination of both were subjected to standard patch endarterectomy. Postoperative wound hematoma was assessed as moderate (subcutaneous bleeding, nonspace-occupying hematoma, and oozing suture bleeding) or severe, i.e., needing operative re-exploration. RESULTS: Six hundred eighty-four (80.9%) patients with one of the three types of antiplatelet therapy out of 844 patients registered from 1995 to 2010 were enrolled. Wound hematoma occurred in 27 of 112 (24.1%) patients under combined aspirin and clopidogrel, 33 of 162 (20.4%) under clopidogrel, and 48 of 410 (11.7 %) under aspirin. Relative risk compared to aspirin was 2.4 (95% CI, 1.4 to 4.1) for aspirin and clopidogrel and 1.9 (95% CI, 1.2 to 3.1) for clopidogrel. Severe space-occupying hematoma needing operative re-exploration occurred in four (3.6%) patients under aspirin and clopidogrel, seven (4.3%) under clopidogrel, and five (1.2%) under aspirin. Corresponding relative risks were 3.0 (95% CI, 0.8 to 11.4) for aspirin and clopidogrel and 3.7 (95% CI, 1.1 to 11.7) for clopidogrel. Relative risks remained without relevant change after adjustment for potentially confounding variables. CONCLUSIONS: Dual antiplatelet therapy with combined aspirin and clopidogrel as well as clopidogrel is associated with an increased incidence of perioperative wound hematoma compared to aspirin but on an acceptable low level of incidence. The latter may be achieved by adapting operative procedures to more intensive antiplatelet regimes.

Implementation and efficacy of selective sonographic screening for carotid disease before cardiac surgery.

BACKGROUND: Preoperative carotid sonography with consecutive preventive strategies might reduce stroke risk during cardiac surgery. Since routine sonography in all patients may be unfeasible, an approach to examine preselected patients was investigated. METHODS: A prognostic model predicting carotid disease was developed using the clinical data of 1,768 routinely examined patients. It recommended 1,018 of 4,814 patients of a following collective for selective sonography. Patients recommended for preoperative sonography were compared to those selected in clinical practice. RESULTS: Besides the evaluated predictor variables, a history of syncope/cardiogenic shock and of pulmonary disease was associated with patient selection for sonography in clinical practice, even though both variables were not associated with severe carotid disease. In patients who underwent sonography, although this was not recommended by the prognostic model, severe carotid disease was estimated lower than what was actually detected, suggesting a change in relative relevance of predicting variables along with the change in frequencies of patients' cardiovascular characteristics. CONCLUSION: Prognostic models for selective screening before cardiac surgery may require reevaluation over time, especially when baseline characteristics used for prediction have changed. Criteria used in clinical practice to select patients for screening may differ from those recommended by investigational studies.

Additive Manufactured Polymer-Bonded Isotropic NdFeB Magnets by Stereolithography and Their Comparison to Fused Filament Fabricated and Selective Laser Sintered Magnets.

Magnetic isotropic NdFeB powder with a spherical morphology is used to 3D print magnets by stereolithography (SLA). Complex magnets with small feature sizes in a superior surface quality can be printed with SLA. The magnetic properties of the 3D printed bonded magnets are investigated and compared with magnets manufactured by fused filament fabrication (FFF), and selective laser sintering (SLS). All methods use the same hard magnetic isotropic NdFeB powder material. FFF and SLA use a polymer matrix material as binder, SLS sinters the powder directly. SLA can print magnets with a remanence of 388 mT and a coercivity of 0.923 T. A complex magnetic design for speed wheel sensing applications is presented and printed with all methods.

Simultaneous occurrence and interaction of hypoperfusion and embolism in a patient with severe middle cerebral artery stenosis.

BACKGROUND AND PURPOSE: The coincidence of hemodynamic and embolic findings in patients with stroke from large artery stenosis has suggested an interaction of both pathologies. This has emerged into the hypothesis of an impaired washout of emboli in the presence of hypoperfusion. We propose an additional link between both pathologies. SUMMARY OF CASE: A 48-year-old woman presented with a recurrent symptomatic severe left middle cerebral artery stenosis. MRI depicted left hemispheric ischemic infarcts in the deep and subcortical white matter and in the cortical border zone. One-hour transcranial Doppler monitoring detected 64 microembolic signals distal to the arterial stenosis. Monitoring also revealed recurrent thrombus formation at the stenotic plaque with decline of poststenotic flow velocity followed by embolism with abrupt excessive flow velocity increase and subsequent normalization at the initial baseline level. Cerebrovascular reserve in the distribution territory of the stenosed artery as assessed by transcranial Doppler after carbon dioxide stimulation revealed a normal reserve capacity in periods with baseline poststenotic flow velocity and an exhausted reserve capacity when flow velocity was decreased due to stenotic thrombus formation. CONCLUSIONS: In our patient, adherent thrombus formation resulted in an increasing severity of the stenosis with subsequent vasodilatation and diminution of flow resistance in the depending vascular distribution territory. MRI suggested that adherent thrombi were predominantly washed into terminal supply and border zone brain regions, ie, into regions with supposed maximum vasodilatation and least flow resistance immediately before thrombus avulsion. Preferred wash-in of emboli into regions with low blood flow resistance might be an additional mechanism besides impaired washout in patients with severe large artery disease.

Prognosis after cryptogenic cerebral ischemia in patients with coagulopathies.

BACKGROUND/AIM: Prognosis and optimal secondary prevention in ischemic stroke patients with coagulopathies remain unclear. The goal of this prospective observational multicenter study was to determine the risk of recurrence in cryptogenic stroke patients with either no or defined coagulopathies under various prevention regimens. METHODS: A total of 429 patients from 14 German stroke centers with an acute cryptogenic ischemic stroke or transient ischemic attack in whom specialized coagulation testing for inherited and acquired coagulopathies (factor V Leiden mutation/resistance to activated protein C, prothrombin mutation, deficiencies of protein C, protein S, antithrombin III, anticardiolipin IgG antibodies, lupus anticoagulant) had been performed were included. Biannual follow-up in 339 (79%) of these patients assessed recurrent cerebrovascular events and secondary prevention therapy during a mean period of 2.5 years. RESULTS: A defined coagulopathy was detected in 89 patients with follow-up, whereas no coagulopathy could be found in 250 patients with follow-up (control group). The Kaplan-Meier estimate for recurrent ischemic stroke or transient ischemic attack after 3 years was 13.6% (95% CI: 5.9-21.2%) in patients with a coagulopathy compared to 9.3% (95% CI: 5.4-13.2%) in controls, which was not significant after adjustment for potential risk factors by Cox regression analysis. Only a previous cerebrovascular ischemic event was an independent predictor for risk of recurrence in coagulopathy and control patients. CONCLUSIONS: Our observational data do not indicate a significantly increased risk for recurrent cerebrovascular events in cryptogenic stroke patients with a coagulopathy or any significant influence of the type of antithrombotic treatment.

Additive Manufactured and Topology Optimized Passive Shimming Elements for Permanent Magnetic Systems.

A method to create a highly homogeneous magnetic field by applying topology optimized, additively manufactured passive shimming elements is investigated. The topology optimization algorithm can calculate a suitable permanent and nonlinear soft magnetic design that fulfills the desired field properties. The permanent magnetic particles are bonded in a polyamide matrix and they are manufactured with a low-cost, end-user 3D printer. Stray field measurements and an inverse stray field simulation framework can determine printing and magnetization errors. The customized shimming elements are manufactured by a selective melting process which produces completely dense soft magnetic metal parts. The methodology is demonstrated on a simple example of two axial symmetric cylindrical magnets, which generates a high inhomogeneous magnetic field. In this case, the maximum magnetic field density is 25 mT and the the homogeneity can be increased by a factor of 35 or down to 6‰. Simulation and measurement results point out a good conformity. Additional topology optimizations of more than one shimming element layer show the opportunity to make the manufactured magnetic system even more homogeneous.

Serum neurofilament light: A biomarker of neuroaxonal injury after ischemic stroke.

OBJECTIVE: To explore the utility of serum neurofilament light chain (NfL) as a biomarker for primary and secondary neuroaxonal injury after ischemic stroke (IS) and study its value for the prediction of clinical outcome. METHODS: We used an ultrasensitive single-molecule array assay to measure serum NfL levels in healthy controls (n = 30) and 2 independent cohorts of patients with IS: (1) with serial serum sampling at hospital arrival (n = 196), at days 2, 3, and 7 (n = 89), and up to 6 months post stroke; and (2) with standardized MRI at baseline and at 6 months post stroke, and with cross-sectional serum sampling at 6 months (n = 95). We determined the temporal profile of serum NfL levels, their association with imaging markers of neuroaxonal injury, and with clinical outcome. RESULTS: Patients with IS had higher serum NfL levels compared with healthy controls starting from admission until 6 months post stroke. Serum NfL levels peaked at day 7 (211.2 pg/mL [104.7-442.6], median [IQR]) and correlated with infarct volumes (day 7: partial r = 0.736, p = 1.5 × 10-15). Six months post stroke, patients with recurrent ischemic lesions on MRI (n = 19) had higher serum NfL levels compared to those without new lesions (n = 76, p = 0.002). Serum NfL levels 6 months post stroke further correlated with a quantitative measure of secondary neurodegeneration obtained from diffusion tensor imaging MRI (r = 0.361, p = 0.001). Serum NfL levels 7 days post stroke independently predicted modified Rankin Scale scores 3 months post stroke (cumulative odds ratio [95% confidence interval] = 2.35 [1.60-3.45]; p = 1.24 × 10-05). CONCLUSION: Serum NfL holds promise as a biomarker for monitoring primary and secondary neuroaxonal injury after IS and for predicting functional outcome.

Elevated serum S100B levels indicate a higher risk of hemorrhagic transformation after thrombolytic therapy in acute stroke.

BACKGROUND AND PURPOSE: Intracerebral hemorrhage constitutes an often fatal sequela of thrombolytic therapy in patients with ischemic stroke. Early blood-brain barrier disruption may play an important role, and the astroglial protein S100B is known to indicate blood-brain barrier dysfunction. We investigated whether elevated pretreatment serum S100B levels predict hemorrhagic transformation (HT) in thrombolyzed patients with stroke. METHODS: We retrospectively included 275 patients with ischemic stroke (mean age of 69+/-13 years; 46% female) who had received thrombolytic therapy within 6 hours of symptom onset. S100B levels were determined from pretreatment blood samples. Follow-up brain scans were obtained 24 hours after admission, and HT was classified as either hemorrhagic infarction (1, 2) or parenchymal hemorrhage (1, 2). RESULTS: HT occurred in 80 patients (29%; 45 hemorrhagic infarction, 35 parenchymal hemorrhage). Median S100B values were significantly higher in patients with HT (0.14 versus 0.11 mug/L; P=0.017). An S100B value in the highest quintile corresponded to an OR for any HT of 2.87 (95% CI: 1.55 to 5.32; P=0.001) in univariate analysis and of 2.80 (1.40 to 5.62; P=0.004) after adjustment for age, sex, symptom severity, timespan from symptom onset to hospital admission, vascular risk factors, and storage time of serum probes. A pretreatment S100B value above 0.23 mug/L had only a moderate sensitivity (0.46) and specificity (0.82) for predicting severe parenchymal bleeding (parenchymal hemorrhage 2). CONCLUSIONS: Elevated S100B serum levels before thrombolytic therapy constitute an independent risk factor for HT in patients with acute stroke. Unfortunately, the diagnostic accuracy of S100B is too low for it to function in this context as a reliable biomarker in clinical practice.

Systemic risk score evaluation in ischemic stroke patients (SCALA): a prospective cross sectional study in 85 German stroke units.

BACKGROUND AND PURPOSE: Stratification of patients with transient ischemic attack (TIA) or ischemic stroke (IS) by risk of recurrent stroke can contribute to optimized secondary prevention. We therefore aimed to assess cardiovascular risk factor profiles of consecutive patients hospitalized with TIA/IS to stratify the risk of recurrent stroke according to the Essen Stroke Risk Score (ESRS) and of future cardiovascular events according to the ankle brachial index (ABI) as a marker of generalized atherosclerosis METHODS: In this cross-sectional observational study, 85 neurological stroke units throughout Germany documented cardiovascular risk factor profiles of 10 consecutive TIA/IS patients on standardized questionnaires. Screening for PAD was done with Doppler ultrasonography to calculate the ABI. RESULTS: A total of 852 patients (57% men) with a mean age of 67+/-12.4 years were included of whom 82.9 % had IS. The median National Institutes of Health stroke sum score was 4 (TIA: 1). Arterial hypertension was reported in 71%, diabetes mellitus in 26%, clinical PAD in 10%, and an ABI < or = 0.9 in 51%. An ESRS > or = 3 was observed in 58%, which in two previous retrospective analyses corresponded to a recurrent stroke risk of > or = 4%/year. The correlation between the ESRS and the ABI was low (r = 0.21). CONCLUSION: A high proportion of patients had asymptomatic atherosclerotic disease and a considerable risk of recurrent stroke according to the ABI and ESRS category. The prognostic accuracy as well as the potential benefit of various risk stratification scores in secondary stroke prevention require validation in a larger prospective study.