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Background: Multiple sclerosis (MS) may cause variable functional impairment. The discrepancy between functional impairment and brain imaging findings in patients with MS (PwMS) might be attributed to differential adaptive and consolidation capacities. Modulating those abilities could contribute to a favorable clinical course of the disease.
Objectives: We examined the effect of cerebellar transcranial direct current stimulation (c-tDCS) on locomotor adaptation and consolidation in PwMS using a split-belt treadmill (SBT) paradigm.
Methods: 40 PwMS and 30 matched healthy controls performed a locomotor adaptation task on a SBT. First, we assessed locomotor adaptation in PwMS. In a second investigation, this training was followed by cerebellar anodal tDCS applied immediately after the task ipsilateral to the fast leg (T0). The SBT paradigm was repeated 24 h (T1) and 78 h (T2) post-stimulation to evaluate consolidation.
Results: The gait dynamics and adaptation on the SBT were comparable between PwMS and controls. We found no effects of offline cerebellar anodal tDCS on locomotor adaptation and consolidation. Participants who received the active stimulation showed the same retention index than sham-stimulated subjects at T1 (p = 0.33) and T2 (p = 0.46).
Conclusion: Locomotor adaptation is preserved in people with mild-to-moderate MS. However, cerebellar anodal tDCS applied immediately post-training does not further enhance this ability. Future studies should define the neurobiological substrates of maintained plasticity in PwMS and how these substrates can be manipulated to improve compensation. Systematic assessments of methodological variables for cerebellar tDCS are urgently needed to increase the consistency and replicability of the results across experiments in various settings.
Background and Purpose: Internal carotid artery stenosis (ICAS)≥70% is a leading cause of ischemic cerebrovascular events (ICVEs). However, a considerable percentage of stroke survivors with symptomatic ICAS (sICAS) have <70% stenosis with a vulnerable plaque. Whether the length of ICAS is associated with high risk of ICVEs is poorly investigated. Our main aim was to investigate the relation between the length of ICAS and the development of ICVEs.
Methods: In a retrospective cross-sectional study, we identified 95 arteries with sICAS and another 64 with asymptomatic internal carotid artery stenosis (aICAS) among 121 patients with ICVEs. The degree and length of ICAS as well as plaque echolucency were assessed on ultrasound scans.
Results: A statistically significant inverse correlation between the ultrasound-measured length and degree of ICAS was detected for sICAS≥70% (Spearman correlation coefficient ρ = –0.57, p < 0.001, n = 51) but neither for sICAS<70% (ρ = 0.15, p = 0.45, n = 27) nor for aICAS (ρ = 0.07, p = 0.64, n = 54). The median (IQR) length for sICAS<70% and ≥70% was 17 (15–20) and 15 (12–19) mm (p = 0.06), respectively, while that for sICAS<90% and sICAS 90% was 18 (15–21) and 13 (10–16) mm, respectively (p < 0.001). Among patients with ICAS <70%, a cut-off length of ≥16 mm was found for sICAS rather than aICAS with a sensitivity and specificity of 74.1% and 51.1%, respectively. Irrespective of the stenotic degree, plaques of the sICAS compared to aICAS were significantly more often echolucent (43.2 vs. 24.6%, p = 0.02).
Conclusion: We found a statistically insignificant tendency for the ultrasound-measured length of sICAS<70% to be longer than that of sICAS≥70%. Moreover, the ultrasound-measured length of sICAS<90% was significantly longer than that of sICAS 90%. Among patients with sICAS≥70%, the degree and length of stenosis were inversely correlated. Larger studies are needed before a clinical implication can be drawn from these results.
Platelet collagen interactions at sites of vascular injuries predominantly involve glycoprotein VI (GPVI) and the integrin α2β1. Both proteins are primarily expressed on platelets and megakaryocytes whereas GPVI expression is also shown on endothelial and integrin α2β1 expression on epithelial cells. We recently showed that depletion of GPVI improves stroke outcome without increasing the risk of cerebral hemorrhage. Genetic variants associated with higher platelet surface integrin α2 (ITGA2) receptor levels have frequently been found to correlate with an increased risk of ischemic stroke in patients. However until now, no preclinical stroke study has addressed whether platelet integrin α2β1 contributes to the pathophysiology of ischemia/reperfusion (I/R) injury. Focal cerebral ischemia was induced in C57BL/6 and Itga2\(^{−/−}\) mice by a 60 min transient middle cerebral artery occlusion (tMCAO). Additionally, wild-type animals were pretreated with anti-GPVI antibody (JAQ1) or Fab fragments of a function blocking antibody against integrin α2β1 (LEN/B). In anti-GPVI treated animals, intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment was applied immediately prior to reperfusion. Stroke outcome, including infarct size and neurological scoring was determined on day 1 after tMCAO. We demonstrate that targeting the integrin α2β1 (pharmacologic; genetic) did neither reduce stroke size nor improve functional outcome on day 1 after tMCAO. In contrast, depletion of platelet GPVI prior to stroke was safe and effective, even when combined with rt-PA treatment. Our results underscore that GPVI, but not ITGA2, is a promising and safe target in the setting of ischemic stroke.
Objective
Bridging the gap between experimental stroke and patients by ischemic blood probing during the hyperacute stage of vascular occlusion is crucial to assess the role of inflammation in human stroke and for the development of adjunct treatments beyond recanalization.
Methods
We prospectively observed 151 consecutive ischemic stroke patients with embolic large vessel occlusion of the anterior circulation who underwent mechanical thrombectomy. In all these patients, we attempted microcatheter aspiration of 3 different arterial blood samples: (1) within the core of the occluded vascular compartment and controlled by (2) carotid and (3) femoral samples obtained under physiological flow conditions. Subsequent laboratory analyses comprised leukocyte counting and differentiation, platelet counting, and the quantification of 13 proinflammatory human chemokines/cytokines.
Results
Forty patients meeting all clinical, imaging, interventional, and laboratory inclusion criteria could be analyzed, showing that the total number of leukocytes significantly increased under the occlusion condition. This increase was predominantly driven by neutrophils. Significant increases were also apparent for lymphocytes and monocytes, accompanied by locally elevated plasma levels of the T‐cell chemoattractant CXCL‐11. Finally, we found evidence that short‐term clinical outcome (National Institute of Health Stroke Scale at 72 hours) was negatively associated with neutrophil accumulation.
Interpretation
We provide the first direct human evidence that neutrophils, lymphocytes, and monocytes, accompanied by specific chemokine upregulation, accumulate in the ischemic vasculature during hyperacute stroke and may affect outcome. These findings strongly support experimental evidence that immune cells contribute to acute ischemic brain damage and indicate that ischemic inflammation initiates already during vascular occlusion. Ann Neurol 2020;87:466–479
Background
In acute ischemic stroke, cessation of blood flow causes immediate tissue necrosis within the center of the ischemic brain region accompanied by functional failure in the surrounding brain tissue designated the penumbra. The penumbra can be salvaged by timely thrombolysis/thrombectomy, the only available acute stroke treatment to date, but is progressively destroyed by the expansion of infarction. The underlying mechanisms of progressive infarction are not fully understood.
Methods
To address mechanisms, mice underwent filament occlusion of the middle cerebral artery (MCAO) for up to 4 h. Infarct development was compared between mice treated with antigen-binding fragments (Fab) against the platelet surface molecules GPIb (p0p/B Fab) or rat immunoglobulin G (IgG) Fab as control treatment. Moreover, Rag1\(^{−/−}\) mice lacking T-cells underwent the same procedures. Infarct volumes as well as the local inflammatory response were determined during vessel occlusion.
Results
We show that blocking of the platelet adhesion receptor, glycoprotein (GP) Ibα in mice, delays cerebral infarct progression already during occlusion and thus before recanalization/reperfusion. This therapeutic effect was accompanied by decreased T-cell infiltration, particularly at the infarct border zone, which during occlusion is supplied by collateral blood flow. Accordingly, mice lacking T-cells were likewise protected from infarct progression under occlusion.
Conclusions
Progressive brain infarction can be delayed by blocking detrimental lymphocyte/platelet responses already during occlusion paving the way for ultra-early treatment strategies in hyper-acute stroke before recanalization.
Purpose
By applying diffusor tensor imaging (DTI) in patients with anterior interosseous nerve syndrome (AINS), this proof of principle study aims to quantify the extent of structural damage of a peripheral nerve at the anatomical level of individual fascicles.
Methods
In this institutional review board approved prospective study 13 patients with spontaneous AINS were examined at 3 Tesla including a transversal T2-weighted turbo-spin-echo and a spin-echo echo-planar-imaging pulse sequence of the upper arm level. Calculations of quantitative DTI parameters including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) for median nerve lesion and non-lesion fascicles as well as ulnar and radial nerve were obtained. DTI values were compared to each other and to a previously published dataset of 58 healthy controls using one-way Analysis of Variance with Bonferroni correction and p-values <.05 were considered significant. Receiver operating characteristic (ROC) curves were performed to assess diagnostic accuracy.
Results
FA of median nerve lesion fascicles was decreased compared to median nerve non-lesion fascicles, ulnar nerve and radial nerve while MD, RD, and AD was increased (p < .001 for all parameters). Compared to median nerve values of healthy controls, lesion fascicles showed a significant decrease in FA while MD, RD, and AD was increased (p < .001 for all parameters). FA of median nerve non-lesion fascicles showed a weak significant decrease compared to healthy controls (p < .01) while there was no difference in MD, RD, and AD. ROC analyses revealed an excellent diagnostic accuracy of FA, MD and RD in the discrimination of median nerve lesion and non-lesion fascicles in AINS patients as well as in the discrimination of lesion fascicles and normative median nerve values of healthy controls.
Conclusion
By applying this functional MR Neurography technique in patients with AINS, this proof of principle study demonstrates that diffusion tensor imaging is feasible to quantify structural nerve injury at the anatomical level of individual fascicles.