Risk factors and clinical significance of post-stroke incident ischemic lesions.

INTRODUCTION: While incident ischemic lesions (IILs) are not unusual on follow-up magnetic resonance imaging (MRI) following stroke, their risk factors and prognostic significance remain unknown. METHODS: In a prospective multicenter study of 503 acute stroke patients, we assessed IILs on registered MRI images at baseline and 6 months, analyzing risk factors and clinical outcomes across 36 months. RESULTS: At 6 months, 78 patients (15.5%) had IILs, mostly diffusion-weighted imaging-positive (72%) and clinically covert (91%). Older age and small vessel disease (SVD) lesions were baseline risk factors for IILs. IILs were associated with worse cognitive (beta for global cognition: -0.31, 95% confidence interval [CI]: -0.48 to -0.14) and functional outcomes (beta for modified Rankin scale [mRS]: 0.36, 95% CI: 0.14 to 0.58), and higher recurrent stroke risk (hazard ratio: 3.81, 95% CI: 1.35 to 10.69). IILs partially explained the relationship between SVD and poor cognition. DISCUSSION: IILs are common and are associated with worse cognitive and functional outcomes and stroke recurrence risk. Assessing IILs following stroke might aid prognostication. HIGHLIGHTS: Incident ischemic lesions (IILs) were assessed with registered baseline and 6-month magnetic resonance imaging (MRI) scans in a stroke cohort. IILs 6 months after stroke are present in one-sixth of patients and are mostly clinically silent. Small vessel disease burden is the main baseline risk factor for IILs. IILs are associated with cognitive and functional impairment and stroke recurrence. Assessing IILs by follow-up MRI aids long-term prognostication for stroke patients.

Serum anti-NMDA receptor antibodies are linked to memory impairment 12 months after stroke.

Patients suffering from strokes are at increased risk of developing post-stroke dementia. Serum anti-NMDA receptor autoantibodies (NMDAR1-abs) have been associated with unfavorable post-stroke outcomes. However, their effect on specific cognitive domains remains unclear. We used data from the prospective multicenter DZNE-mechanisms after stroke (DEMDAS) cohort, and measured NMDAR1-abs in serum at baseline. Cognitive function was assessed with a comprehensive neuropsychological test battery at 6- and 12-months follow-up. We employed crude and stepwise confounder adjusted linear and logistic regression models as well as generalized estimating equation models (GEE) to determine the relevance of NMDAR1-abs seropositivity on cognitive function after stroke. 10.2% (58/569) DEMDAS patients were NMDAR1-abs seropositive (IgM:n = 44/IgA:n = 21/IgG:n = 2). Seropositivity was not associated with global cognitive impairment after stroke. However, NMDAR1-abs seropositive patients performed lower in the memory domain (ßadjusted = -0.11; 95%CI = -0.57 to -0.03) and were at increased risk for memory impairment (ORadjusted = 3.8; 95%CI = 1.33-10.82) compared to seronegative patients, 12 months after stroke. Further, NMDAR1-abs were linked to memory impairment over time in GEE from 6- to 12-months follow-up (ORadjusted = 2.41; 95%CI = 1.05-5.49). Our data suggests that NMDAR1-abs contribute to memory dysfunction 1 year after stroke while not affecting other cognitive subdomains. Hence, antineuronal autoimmunity may be involved in distinct mechanisms of post-stroke memory impairment. Clinical trial name and registration number: The Determinants of Dementia After Stroke (DEMDAS; study identifier on clinical trials.gov: NCT01334749).

Hebbian plasticity induced by temporally coincident BCI enhances post-stroke motor recovery.

Functional electrical stimulation (FES) can support functional restoration of a paretic limb post-stroke. Hebbian plasticity depends on temporally coinciding pre- and post-synaptic activity. A tight temporal relationship between motor cortical (MC) activity associated with attempted movement and FES-generated visuo-proprioceptive feedback is hypothesized to enhance motor recovery. Using a brain-computer interface (BCI) to classify MC spectral power in electroencephalographic (EEG) signals to trigger FES-delivery with detection of movement attempts improved motor outcomes in chronic stroke patients. We hypothesized that heightened neural plasticity earlier post-stroke would further enhance corticomuscular functional connectivity and motor recovery. We compared subcortical non-dominant hemisphere stroke patients in BCI-FES and Random-FES (FES temporally independent of MC movement attempt detection) groups. The primary outcome measure was the Fugl-Meyer Assessment, Upper Extremity (FMA-UE). We recorded high-density EEG and transcranial magnetic stimulation-induced motor evoked potentials before and after treatment. The BCI group showed greater: FMA-UE improvement; motor evoked potential amplitude; beta oscillatory power and long-range temporal correlation reduction over contralateral MC; and corticomuscular coherence with contralateral MC. These changes are consistent with enhanced post-stroke motor improvement when movement is synchronized with MC activity reflecting attempted movement.

Risk factors for intracerebral hemorrhage in small-vessel disease and non-small-vessel disease etiologies-an observational proof-of-concept study.

Background: Sporadic cerebral small-vessel disease (CSVD), i.e., hypertensive arteriopathy (HA) and cerebral amyloid angiopathy (CAA), is the main cause of spontaneous intracerebral hemorrhage (ICH). Nevertheless, a substantial portion of ICH cases arises from non-CSVD etiologies, such as trauma, vascular malformations, and brain tumors. While studies compared HA- and CAA-related ICH, non-CSVD etiologies were excluded from these comparisons and are consequently underexamined with regard to additional factors contributing to increased bleeding risk beyond their main pathology. Methods: As a proof of concept, we conducted a retrospective observational study in 922 patients to compare HA, CAA, and non-CSVD-related ICH with regard to factors that are known to contribute to spontaneous ICH onset. Medical records (available for n = 861) were screened for demographics, antithrombotic medication, and vascular risk profile, and CSVD pathology was rated on magnetic resonance imaging (MRI) in a subgroup of 185 patients. The severity of CSVD was assessed with a sum score ranging from 0 to 6, where a score of ≥2 was defined as advanced pathology. Results: In 922 patients with ICH (median age of 71 years), HA and CAA caused the majority of cases (n = 670, 73%); non-CSVD etiologies made up the remaining quarter (n = 252, 27%). Individuals with HA- and CAA-related ICH exhibited a higher prevalence of predisposing factors than those with non-CSVD etiologies. This includes advanced age (median age: 71 vs. 75 vs. 63 years, p < 0.001), antithrombotic medication usage (33 vs. 37 vs. 19%, p < 0.001), prevalence of vascular risk factors (70 vs. 67 vs. 50%, p < 0.001), and advanced CSVD pathology on MRI (80 vs. 89 vs. 51%, p > 0.001). However, in particular, half of non-CSVD ICH patients were either aged over 60 years, presented with vascular risk factors, or had advanced CSVD on MRI. Conclusion: Risk factors for spontaneous ICH are less common in non-CSVD ICH etiologies than in HA- and CAA-related ICH, but are still frequent. Future studies should incorporate these factors, in addition to the main pathology, to stratify an individual's risk of bleeding.

KCNA2 IgG autoimmunity in neuropsychiatric diseases.

BACKGROUND: Autoantibodies against the potassium voltage-gated channel subfamily A member 2 (KCNA2) have been described in a few cases of neuropsychiatric disorders, but their diagnostic and pathophysiological role is currently unknown, imposing challenges to medical practice. DESIGN / METHODS: We retrospectively collected comprehensive clinical and paraclinical data of 35 patients with KCNA2 IgG autoantibodies detected in cell-based and tissue-based assays. Patients' sera and cerebrospinal fluid (CSF) were used for characterization of the antigen, clinical-serological correlations, and determination of IgG subclasses. RESULTS: KCNA2 autoantibody-positive patients (n = 35, median age at disease onset of 65 years, range of 16-83 years, 74 % male) mostly presented with cognitive impairment and/or epileptic seizures but also ataxia, gait disorder and personality changes. Serum autoantibodies belonged to IgG3 and IgG1 subclasses and titers ranged from 1:32 to 1:10,000. KCNA2 IgG was found in the CSF of 8/21 (38 %) patients and in the serum of 4/96 (4.2 %) healthy blood donors. KCNA2 autoantibodies bound to characteristic anatomical areas in the cerebellum and hippocampus of mammalian brain and juxtaparanodal regions of peripheral nerves but reacted exclusively with intracellular epitopes. A subset of four KCNA2 autoantibody-positive patients responded markedly to immunotherapy alongside with conversion to seronegativity, in particular those presenting an autoimmune encephalitis phenotype and receiving early immunotherapy. An available brain biopsy showed strong immune cell invasion. KCNA2 autoantibodies occurred in less than 10 % in association with an underlying tumor. CONCLUSION: Our data suggest that KCNA2 autoimmunity is clinically heterogeneous. Future studies should determine whether KCNA2 autoantibodies are directly pathogenic or develop secondarily. Early immunotherapy should be considered, in particular if autoantibodies occur in CSF or if clinical or diagnostic findings suggest ongoing inflammation. Suspicious clinical phenotypes include autoimmune encephalitis, atypical dementia, new-onset epilepsy and unexplained epileptic seizures.

Cerebral small vessel disease burden and cognitive and functional outcomes after stroke: A multicenter prospective cohort study.

INTRODUCTION: It remains unknown whether the global small vessel disease (SVD) burden predicts post-stroke outcomes. METHODS: In a prospective multicenter study of 666 ischemic and hemorrhagic stroke patients, we quantified magnetic resonance imaging (MRI)-based SVD markers (lacunes, white matter hyperintensities, microbleeds, perivascular spaces) and explored associations with 6- and 12-month cognitive (battery of 15 neuropsychological tests) and functional (modified Rankin scale) outcomes. RESULTS: A global SVD score (range 0-4) was associated with cognitive impairment; worse performance in executive function, attention, language, and visuospatial ability; and worse functional outcome across a 12-month follow-up. Although the global SVD score did not improve prediction, individual SVD markers, assessed across their severity range, improved the calibration, discrimination, and reclassification of predictive models including demographic, clinical, and other imaging factors. DISCUSSION: SVD presence and severity are associated with worse cognitive and functional outcomes 12 months after stroke. Assessing SVD severity may aid prognostication for stroke patients. HIGHLIGHTS: In a multi-center cohort, we explored associations of small vessel disease (SVD) burden with stroke outcomes. SVD burden associates with post-stroke cognitive and functional outcomes. A currently used score of SVD burden does not improve the prediction of poor outcomes. Assessing the severity of SVD lesions adds predictive value beyond known predictors. To add predictive value in assessing SVD in stroke patients, SVD burden scores should integrate lesion severity.

[Intraoperative angiography in carotid artery reconstruction-Pathological findings, reliability and importance of the procedure]. / Intraoperative Angiographie bei A.-carotis-Rekonstruktion ­ pathologische Befunde, Zuverlässigkeit und Bedeutung des Verfahrens.

AIM: To investigate the value of intraoperative angiography and its ad hoc evaluation with respect to cases of surgical technical inaccessibility. METHODS: Overall, 523 consecutive carotid artery thrombendarterectomy (TEA) patients with intraoperative control angiography, postoperative color-coded duplex sonography and retrospective re-evaluation of documented angiographic images were included in the evaluation. RESULTS: In the retrospective angiographic re-evaluation 23 (4.4%) occlusions or high-grade stenoses of the common carotid artery (CCA) or internal carotid artery (ICA) in the surgical field (12, 2.3%) or of downstream ICA or middle cerebral artery (MCA, 11, 2.1%) were detected. The detection rate was significantly lower in the intraoperative ad hoc evaluation with overall only 13 (2.5%) detected pathologies (7, 1.3% in the surgical field, 6, 1.1% in large downstream arteries, p=0.002). Postoperative duplex sonography performed in 505 patients detected 50 cases (10.1%) of local surgical technical inaccessibility, which was significantly more than in the angiography (p<0.001). In most cases these were nonocclusive, low-grade stenosing detachments of the intima media (n=19), 13 suture contractions, and 14 kinking/abrupt diameter changes at the distal end of the patch. Suture contractions and kinking/diameter changes were associated with a left-sided TEA (adjusted odds ratio, OR 2.4, 95% confidence interval, CI 1.1-5.1), an operation without a patch (adjusted OR, 16.6, 95% CI 1.3-215.0), and using Dacron patches in contrast to PTFE patches (adjusted OR 3.0, 95% CI 1.4-6.6). CONCLUSION: The ad hoc evaluation of intraoperative completion angiography by surgeons missed a substantial number also of occluding and severely stenosing pathologies. Angiography is not suitable for the detection of nonocclusive and low-grade stenosing cases of operative inaccessibility. Postoperative color-coded duplex sonography is an adequate tool for surgical quality control.

MRI phenotyping of underlying cerebral small vessel disease in mixed hemorrhage patients.

OBJECTIVE: To investigate underlying cerebral small vessel disease (CSVD) in patients with mixed cerebral hemorrhages patterns and phenotype them according to the contribution of the two most common sporadic CSVD subtypes: cerebral amyloid angiopathy (CAA) vs. hypertensive arteriopathy (HA). METHODS: Brain MRIs of patients with intracerebral hemorrhages (ICHs) and/or cerebral microbleeds (CMBs) were assessed for the full spectrum of CSVD markers using validated scales: ICHs, CMBs, cortical superficial siderosis (cSS), white matter hyperintensities, MRI-visible perivascular spaces (PVS). PVS predominance pattern was grouped as centrum-semiovale (CSO)-PVS predominance, basal-ganglia (BG)-PVS predominance, CSO-PVS and BG-PVS equality. Patients with mixed cerebral hemorrhages were classified into mixed CAA-pattern or mixed HA-pattern according to the existence of cSS and/or a CSO-PVS predominance pattern and comparisons were performed. RESULTS: We included 110 patients with CAA (strictly lobar ICHs/CMBs), 33 with HA (strictly deep ICHs/CMBs) and 97 with mixed lobar/deep ICHs/CMBs. Mixed patients were more similar to HA with respect to their MRI-CSVD markers, vascular risk profile and cerebrospinal fluid (CSF) measures. In the mixed patients, 33 (34%) had cSS, a CSO-PVS predominance pattern, or both, and were defined as mixed CAA-pattern cases. The mixed CAA-pattern patients were more alike CAA patients regarding their MRI-CSVD markers, CSF and genetic profile. CONCLUSION: Our findings suggest that the heterogeneous group of patients with mixed cerebral hemorrhages distribution can be further phenotyped according to the predominant underlying CSVD. cSS presence and a CSO-PVS predominance pattern could serve as strongly suggestive markers of a contribution from CAA among patients with mixed hemorrhages.

Influence of Melt-Pool Stability in 3D Printing of NdFeB Magnets on Density and Magnetic Properties.

The current work presents the results of an investigation focused on the influence of process parameters on the melt-track stability and its consequence to the sample density printed out of NdFeB powder. Commercially available powder of Nd7.5Pr0.7Fe75.4Co2.5B8.8Zr2.6Ti2.5 alloy was investigated at the angle of application in selective laser melting of permanent magnets. Using single track printing the stability of the melt pool was investigated under changing process parameters. The influence of changing laser power, scanning speed, and powder layer thickness on density, porosity structure, microstructure, phase composition, and magnetic properties were investigated. The results showed that energy density coupled with powder layer thickness plays a crucial role in melt-track stability. It was possible to manufacture magnets of both high relative density and high magnetic properties. Magnetization tests showed a significant correlation between the shape of the demagnetization curve and the layer height. While small layer heights are beneficial for sufficient magnetic properties, the remaining main parameters tend to affect the magnetic properties less. A quasi-linear correlation between the layer height and the magnetic properties remanence (Jr), coercivity (HcJ) and maximum energy product ((BH)max) was found.

Beware the intruder: Real time observation of infiltrated neutrophils and neutrophil-Microglia interaction during stroke in vivo.

Inflammation plays an important role in the pathogenesis of ischemic stroke including an acute and prolonged inflammatory process. The role of neutrophil granulocytes as first driver of the immune reaction from the blood site is under debate due to controversial findings. In bone marrow chimeric mice we were able to study the dynamics of tdTomato-expressing neutrophils and GFP-expressing microglia after photothrombosis using intravital two-photon microscopy. We demonstrate the infiltration of neutrophils into the brain parenchyma and confirm a long-lasting contact between neutrophils and microglia as well as an uptake of neutrophils by microglia clearing the brain from peripheral immune cells.

Very-late-antigen-4 (VLA-4)-mediated brain invasion by neutrophils leads to interactions with microglia, increased ischemic injury and impaired behavior in experimental stroke.

Neuronal injury from ischemic stroke is aggravated by invading peripheral immune cells. Early infiltrates of neutrophil granulocytes and T-cells influence the outcome of stroke. So far, however, neither the timing nor the cellular dynamics of neutrophil entry, its consequences for the invaded brain area, or the relative importance of T-cells has been extensively studied in an intravital setting. Here, we have used intravital two-photon microscopy to document neutrophils and brain-resident microglia in mice after induction of experimental stroke. We demonstrated that neutrophils immediately rolled, firmly adhered, and transmigrated at sites of endothelial activation in stroke-affected brain areas. The ensuing neutrophil invasion was associated with local blood-brain barrier breakdown and infarct formation. Brain-resident microglia recognized both endothelial damage and neutrophil invasion. In a cooperative manner, they formed cytoplasmic processes to physically shield activated endothelia and trap infiltrating neutrophils. Interestingly, the systemic blockade of very-late-antigen-4 immediately and very effectively inhibited the endothelial interaction and brain entry of neutrophils. This treatment thereby strongly reduced the ischemic tissue injury and effectively protected the mice from stroke-associated behavioral impairment. Behavioral preservation was also equally well achieved with the antibody-mediated depletion of myeloid cells or specifically neutrophils. In contrast, T-cell depletion more effectively reduced the infarct volume without improving the behavioral performance. Thus, neutrophil invasion of the ischemic brain is rapid, massive, and a key mediator of functional impairment, while peripheral T-cells promote brain damage. Acutely depleting T-cells and inhibiting brain infiltration of neutrophils might, therefore, be a powerful early stroke treatment.

[Ischemic stroke--diagnosis and treatment]. / Ischämischer Insult - Diagnostik und Therapie.

Management of ischemic stroke is targeted on four therapeutic objectives: limitation of neurological deficit, prevention of earyl stroke recurrence, protection against complications, and secondary prevention. Intravenous thrombolysis within 4.5h of stroke onset is the only proven therapy to improvefunctional outcome. Although promising, neither endovascular recanalisation nor neuroprotective strategies have demonstrated efficacy so far. Immediate administration of antiplatelet agents like acetylsalicylic acid and clopidogrel - in case of intravenous thrombolysis at the earliest after 24h - is effective to prevent early stroke recurrence, whereas anticoagulants should be ommitted in this stage because of an increased risk of cerebral hemorrhage. Subcutaneous heparin/low molecular weight heparin, mobilisation, nasogastric tube, and decompressive craniectomy may protect from venous thromboembolism, aspiration pneumonia, and malignant brain edema, respectively. Secondary prevention is guided by stroke etiology, e.g. oral anticoagulation in the presence atrial fibrillation or endarterectomy in case of sympomatic high-grade carotid stenosis.