Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a cluster of various vascular disorders with different pathological backgrounds. The advanced vasculature net of cerebral vessels, including small arteries, capillaries, arterioles and venules, is usually affected. Processes of oxidation underlie the pathology of CSVD, promoting the degenerative status of the epithelial layer. There are several classifications of cerebral small vessel diseases; some of them include diseases such as Binswanger’s disease, leukoaraiosis, cerebral microbleeds (CMBs) and lacunar strokes. This paper presents the characteristics of CSVD and the impact of the current knowledge of this topic on the diagnosis and treatment of patients.

Effect of alteplase versus aspirin plus clopidogrel in acute minor stroke

Background and purpose: The optimal treatment for acute ischemic stroke with mild neurologic deficits is unclear. We aimed to compare the efficacy and safety of alteplase versus dual-antiplatelet therapy in acute minor stroke.Methods: We performed a retrospective cohort study of patients with minor ischemic stroke and National Institutes of Health Stroke Scale scores ≤5 presenting within 24 h from last seen normal. Patients were divided into intravenous alteplase or dual-antiplatelet therapy group. The primary outcome was a modified Rankin Scale (mRS) score of 0 or 1 at 90 days. Secondary outcomes included mRS score at 7 days, and composite outcome of vascular events within 90 days. The safety outcome was any intracranial hemorrhage (ICH) according to the ECASS II criteria. Clinical outcomes were compared using a multivariable logistic regression after adjusting for confounding factors. We then performed the propensity score matching as a sensitivity analysis.Results: Two hundred twenty-eight patients met the eligibility criteria were included for analysis between January 2015 and September 2018. In the aspirin-clopidogrel group, 109 patients (91.6%) achieved a favorable functional outcome at 3-month versus 85(78.0%) in the alteplase group (OR 4.463, 95%CI 1.708-11.662, p = .002). The difference of the composite outcome of vascular events were not statistical significance between the two groups (p > .05). Asymptomatic ICH occurred in 0.8% patients who received aspirin-clopidogrel, as compared with 3.7% patients in alteplase group (p = .030).Conclusions: Patients treated with dual-antiplatelet therapy with acute minor ischemic stroke had greater functional outcome at 3 months compared with patients who received alteplase therapy.Classification of evidence: This study provides Class IV evidence that dual-antiplatelet therapy is superior to alteplase for achieving a better functional outcome and does not increase the risk of hemorrhage in acute minor ischemic stroke.

Impact of Cerebral Small Vessel Disease on Functional Recovery After Intracerebral Hemorrhage

Background and Purpose- In this study, we aim to investigate the association of computed tomography-based markers of cerebral small vessel disease with functional outcome and recovery after intracerebral hemorrhage. Methods- Computed tomographic scans of patients in the ERICH study (Ethnic and Racial Variations of Intracerebral Hemorrhage) were evaluated for the extent of leukoaraiosis and cerebral atrophy using visual rating scales. Poor functional outcome was defined as a modified Rankin Scale (mRS) of ≥3. Multivariable logistic and linear regression models were used to explore the associations of cerebral small vessel disease imaging markers with poor functional outcome at discharge and, as a measure of recovery, change in mRS from discharge to 90 days poststroke. Results- After excluding in-hospital deaths, data from 2344 patients, 583 (24.9%) with good functional outcome (mRS of 0-2) at discharge and 1761 (75.1%) with poor functional outcome (mRS of 3-5) at discharge, were included. Increasing extent of leukoaraiosis (P for trend, 0.01) and only severe (grade 4) global atrophy (odds ratio, 2.02; 95% CI, 1.22-3.39, P=0.007) were independently associated with poor functional outcome at discharge. Mean (SD) mRS change from discharge to 90-day follow-up was 0.57 (1.18). Increasing extent of leukoaraiosis (P for trend, 0.002) and severe global atrophy (β [SE], -0.23 [0.115]; P=0.045) were independently associated with less improvement in mRS from discharge to 90 days poststroke. Conclusions- In intracerebral hemorrhage survivors, the extent of cerebral small vessel disease at the time of intracerebral hemorrhage is associated with poor functional outcome at hospital discharge and impaired functional recovery from discharge to 90 days poststroke.

Recent Advances in Leukoaraiosis: White Matter Structural Integrity and Functional Outcomes after Acute Ischemic Stroke

Leukoaraiosis, a radiographic marker of cerebral small vessel disease detected on T2-weighted brain magnetic resonance imaging (MRI) as white matter hyperintensity (WMH), is a key contributor to the risk and severity of acute cerebral ischemia. Prior investigations have emphasized the pathophysiology of WMH development and progression; however, more recently, an association between WMH burden and functional outcomes after stroke has emerged. There is growing evidence that WMH represents macroscopic injury to the white matter and that the extent of WMH burden on MRI influences functional recovery in multiple domains following acute ischemic stroke (AIS). In this review, we discuss the current understanding of WMH pathogenesis and its impact on AIS and functional recovery.

Late-onset major depression is associated with age-related white matter lesions in the brainstem

OBJECTIVE

Age-related white matter lesions (ARWMLs) have been identified in various clinical conditions such as reduced gait speed, cognitive impairment, urogenital dysfunction, and mood disturbances. Previous studies indicated an association between ARWML and late-onset major depression. However, most of these focused on the extent of supratentorial ARWML and neglected presence and degree of infratentorial lesions.

METHODS

In 45 patients (mean age 73.7 ± 6.3 years, 17 (37.8%) men, 28 (62.2%) women) with late-onset major depression, MRI findings (3.0-T MR system, Magnetom Trio, Siemens Medical Systems, Erlangen, Germany) were analyzed with emphasis on the extent of supratentorial and infratentorial, as well as brainstem ARWMLs, and compared with control subjects. ARWMLs were determined by semiquantitative rating scales (modified Fazekas rating scale, Scheltens' rating scale), as well as a semiautomatic volumetric assessment, using a specific software (MRIcron). Supratentorial and infratentorial, as well as brainstem ARWMLs, were assessed both on fluid attenuated inversion recovery and T2-weighted images.

RESULTS

Patients with late-onset major depression had significantly higher infratentorial ARWML rating scores (5 (5-7) vs 4.5 (3-6), p = 0.003) on T2-weighted images and volumes (1.58 ± 1.35 mL vs 1.05 ± 0.81 mL, p = 0.03) on T2-weighted images, as well as fluid attenuated inversion recovery images (2.07 ± 1.35 mL vs 1.52 ± 1.10 mL, p = 0.04), than normal controls. In more detail, in particular, the pontine ARWML rating subscore was significantly higher in patients with late-onset major depression (1 (1-2) vs 1 (1-1), p = 0.004).

CONCLUSIONS

The extent and localization of brainstem ARWML might be of importance for the pathophysiology of late-onset major depression. In particular, this may hold true for pontine ARWML. Copyright © 2016 John Wiley & Sons, Ltd.

Prediction of motor outcome using remaining corticospinal tract in patients with pontine infarct: Diffusion tensor imaging study

The aim of this study was to investigate the relationship between the remaining corticospinal tract (CST) as determined by diffusion tensor imaging (DTI) and 6-month motor outcome in patients with pontine infarct. Ratios of fractional anisotropy (FA), fiber number (FN), and CST area were calculated, and the FN ratio and CST area ratio showed significant correlation with all 6-month motor outcome. Thus, the remaining CST in the pons measured using DTI at early stage of stroke could predict motor outcome in patients with pontine infarct.

Changes in brain functional network connectivity after stroke

Studies have shown that functional network connection models can be used to study brain network changes in patients with schizophrenia. In this study, we inferred that these models could also be used to explore functional network connectivity changes in stroke patients. We used independent component analysis to find the motor areas of stroke patients, which is a novel way to determine these areas. In this study, we collected functional magnetic resonance imaging datasets from healthy controls and right-handed stroke patients following their first ever stroke. Using independent component analysis, six spatially independent components highly correlated to the experimental paradigm were extracted. Then, the functional network connectivity of both patients and controls was established to observe the differences between them. The results showed that there were 11 connections in the model in the stroke patients, while there were only four connections in the healthy controls. Further analysis found that some damaged connections may be compensated for by new indirect connections or circuits produced after stroke. These connections may have a direct correlation with the degree of stroke rehabilitation. Our findings suggest that functional network connectivity in stroke patients is more complex than that in hea-lthy controls, and that there is a compensation loop in the functional network following stroke. This implies that functional network reorganization plays a very important role in the process of rehabilitation after stroke.

Connectivity-based approaches in stroke and recovery of function

After focal damage, cerebral networks reorganise their structural and functional anatomy to compensate for both the lesion itself and remote effects. Novel developments in the analysis of functional neuroimaging data enable us to assess in vivo the specific contributions of individual brain areas to recovery of function and the effect of treatment on cortical reorganisation. Connectivity analyses can be used to investigate the effect of stroke on cerebral networks, and help us to understand why some patients make a better recovery than others. This systems-level view also provides insights into how neuromodulatory interventions might target pathological network configurations associated with incomplete recovery. In the future, such analyses of connectivity could help to optimise treatment regimens based on the individual network pathology underlying a particular neurological deficit, thereby opening the way for stratification of patients based on the possible response to an intervention.

[Multimodal imaging protocols and their predictive role in acute stroke functional outcome]

Brain imaging plays a central role in the assessment of patients with acute ischemic stroke. Within a few minutes, modern multimodal imaging protocols can provide one with comprehensive information about prognosis, management, and outcome of the disease, and may detect changes in the intracranial structures reflecting severity of the ischemic injury depicted by four Ps: parenchyma (of the brain), pipes (i.e., the cerebral blood vessels), penumbra, and permeability (of the blood brain barrier). In this article, we have reviewed neuroradiological predictors of stroke functional outcome in the light of the aforementioned four Ps.

Cortical reorganization after stroke: how much and how functional?

The brain has an intrinsic capacity to compensate for structural damage through reorganizing of surviving networks. These processes are fundamental for recovery of function after many forms of brain injury, including stroke. Functional neuroimaging techniques have allowed the investigation of these processes in vivo. Here, we review key advances over the past two decades that have shed light on the neural mechanisms enabling recovery of motor function after stroke. We first provide an overview on invasive stroke models in non-human primates that provided insights into lesion-induced changes in the cortical representations of the upper limb. We then present key findings from neuroimaging studies in human stroke patients, which suggest that the role of contralesional motor hemisphere in supporting recovered function depends on factors such as time since stroke, lesion location and anatomical region. More recently, research has been directed at understanding how surviving brain regions influence one another during movement. It appears that it is not only the corticospinal tract but also brainstem pathways and interhemispheric connections that affect cortical reorganization patterns and functional recovery. In summary, neuroimaging opens the way for greater understanding of the mechanisms of recovery and potentially improves our ability to deliver effective restorative therapy.

Diffusion magnetic resonance imaging for Brainnetome: a critical review

Increasing evidence shows that the human brain is a highly self-organized system that shows attributes of small-worldness, hierarchy and modularity. The "connectome" was conceived several years ago to identify the underpinning physical connectivities of brain networks. The need for an integration of multi-spatial and -temporal approaches is becoming apparent. Therefore, the "Brainnetome" (brain-net-ome) project was proposed. Diffusion magnetic resonance imaging (dMRI) is a non-invasive way to study the anatomy of brain networks. Here, we review the principles of dMRI, its methodologies, and some of its clinical applications for the Brainnetome. Future research in this field is discussed.