•Motor recovery after stroke is a multifactorial and dynamic process.•Advanced age, African American race, and female gender are major socioeconomic factors affecting stroke recovery.•Extent of ...initial injury after stroke is a major independent predictor of recovery.•Neurorehabilitation strategies provide a unique opportunity for enhancing recovery.•Genetic polymorphisms especially in BDNF may influence post-stroke recovery process.
Neurological disorders are a major cause of chronic disability globally among which stroke is a leading cause of chronic disability. The advances in the medical management of stroke patients over the past decade have significantly reduced mortality, but at the same time increased numbers of disabled survivors. Unfortunately, this reduction in mortality was not paralleled by satisfactory therapeutics and rehabilitation strategies that can improve functional recovery of patients. Motor recovery after brain injury is a complex, dynamic, and multifactorial process in which an interplay among genetic, pathophysiologic, sociodemographic and therapeutic factors determines the overall recovery trajectory. Although stroke recovery is the most well-studied form of post-injury neuronal recovery, a thorough understanding of the pathophysiology and determinants affecting stroke recovery is still lacking. Understanding the different variables affecting brain recovery after stroke will not only provide an opportunity to develop therapeutic interventions but also allow for developing personalized platforms for patient stratification and prognosis. We aim to provide a narrative review of major determinants for post-stroke recovery and their implications in other forms of brain injury.
There has been a significant increase in obesity rates worldwide with the corresponding surge in diabetes. Diabetes causes various microvascular and macrovascular changes often culminating in major ...clinical complications, 1 of which, is stroke. Although gains have been made over the last 2 decades in reducing the burden of stroke, the recent rise in rates of diabetes threatens to reverse these advances. Of the several mechanistic stroke subtypes, individuals with diabetes are especially susceptible to the consequences of cerebral small vessel diseases. Hyperglycemia confers greater risk of stroke occurrence. This increased risk is often seen in individuals with diabetes and is associated with poorer clinical outcomes (including higher mortality), especially following ischemic stroke. Improving stroke outcomes in individuals with diabetes requires prompt and persistent implementation of evidence-based medical therapies as well as adoption of beneficial lifestyle practices.
Survivors of stroke often experience significant disability and impaired quality of life. The recovery of motor or cognitive function requires long periods. Neuroimaging could measure changes in the ...brain and monitor recovery process in order to offer timely treatment and assess the effects of therapy. A non-invasive neuroimaging technique near-infrared spectroscopy (NIRS) with its ambulatory, portable, low-cost nature without fixation of subjects has attracted extensive attention.
We conducted a comprehensive literature review in order to review the use of NIRS in stroke or post-stroke patients in July 2018. NCBI Pubmed database, EMBASE database, Cochrane Library and ScienceDirect database were searched.
Overall, we reviewed 66 papers. NIRS has a wide range of application, including in monitoring upper limb, lower limb recovery, motor learning, cortical function recovery, cerebral hemodynamic changes, cerebral oxygenation, as well as in therapeutic method, clinical researches, and evaluation of the risk for stroke.
This study provides a preliminary evidence of the application of NIRS in stroke patients as a monitoring, therapeutic, and research tool. Further studies could give more emphasize on the combination of NIRS with other techniques and its utility in the prevention of stroke.
Objective
The aim of this work was to investigate whether an imaging measure of corticospinal tract (CST) injury in the acute phase can predict motor outcome at 3 months in comparison to clinical ...assessment of initial motor impairment.
Methods
A two‐site prospective cohort study followed up a group of first‐ever ischemic stroke patients using the Upper‐Extremity Fugl‐Meyer (UE‐FM) Scale to measure motor impairment in the acute phase and at 3 months. A weighted CST lesion load (wCST‐LL) was calculated by overlaying the patient's lesion map on magnetic resonance imaging with a probabilistic CST constructed from healthy control subjects. Regression models were fit to assess the predictive value of wCST‐LL and compared with initial motor impairment.
Results
Seventy‐six patients (37 from cohort 1 and 39 from cohort 2) completed the study. wCST‐LL as well as assessment of motor impairment (UE‐FM) in the acute phase correlated with motor impairment (UE‐FM) at 3 months in both cohort 1 (R2 = 0.69 vs. R2 = 0.67; p = 0.43) and cohort 2 (R2 = 0.69 vs. R2 = 0.62; p = 0.25). In the severely impaired subgroup (defined as UE‐FM ≤ 10 at baseline), wCST‐LL correlated with outcomes significantly better than clinical assessment (R2 = 0.47 vs. R2 = 0.11; p = 0.03). In the nonseverely impaired subgroup, stroke patients recovered approximately 70% of their maximal recovery potential. All stroke patients in both cohorts had poor motor outcomes at 3 months (defined as UE‐FM ≤ 25) when wCST‐LL was ≥ 7.0 cc (positive predictive value was 100%).
Interpretation
wCST‐LL, an imaging biomarker determined in the acute phase, can predict poststroke motor outcomes at 3 months, especially in patients with severe impairment at baseline. Ann Neurol 2015;78:860–870
Exogenous stem cell therapy (SCT) has been recognized recently as a promising neuroregenerative strategy to augment recovery in stroke survivors. Mesenchymal stem cells (MSCs) are the primary source ...of stem cells used in the majority of both pre-clinical and clinical studies in stroke. In the absence of evidence-based guidelines on the use of SCT in stroke patients, understanding the progress of MSC research across published studies will assist researchers and clinicians in better achieving success in translating research. We conducted a systematic review on published literature using MSCs in both pre-clinical studies and clinical trials between 2008 and 2017 using the public databases PubMed and Ovid Medline, and the clinical trial registry (www.clinicaltrials.gov). A total of 78 pre-clinical studies and eight clinical studies were identified. While majority of the pre-clinical and clinical studies demonstrated statistically significant effects, the clinical significance of these findings was still unclear. Effect sizes could not be measured mainly due to reporting issues in pre-clinical studies, thus limiting our ability to compare results across studies quantitatively. The overall quality of both pre-clinical and clinical studies was sub-optimal. By conducting a systematic review of both pre-clinical and clinical studies on MSCs therapy in stroke, we assessed the quality of current evidence and identified several issues and gaps in translating animal studies to human trials. Addressing these issues and incorporating changes into future animal studies and human trials may lead to better success of stem cells-based therapeutics in the near future.
Purpose of Review
Despite current rehabilitative strategies, stroke remains a leading cause of disability in the USA. There is a window of enhanced neuroplasticity early after stroke, during which ...the brain’s dynamic response to injury is heightened and rehabilitation might be particularly effective. This review summarizes the evidence of the existence of this plastic window, and the evidence regarding safety and efficacy of early rehabilitative strategies for several stroke domain-specific deficits.
Recent Findings
Overall, trials of rehabilitation in the first 2 weeks after stroke are scarce. In the realm of very early mobilization, one large and one small trial found potential harm from mobilizing patients within the first 24 h after stroke, and only one small trial found benefit in doing so. For the upper extremity, constraint-induced movement therapy appears to have benefit when started within 2 weeks of stroke. Evidence for non-invasive brain stimulation in the acute period remains scant and inconclusive. For aphasia, the evidence is mixed, but intensive early therapy might be of benefit for patients with severe aphasia. Mirror therapy begun early after stroke shows promise for the alleviation of neglect. Novel approaches to treating dysphagia early after stroke appear promising, but the high rate of spontaneous improvement makes their benefit difficult to gauge.
Summary
The optimal time to begin rehabilitation after a stroke remains unsettled, though the evidence is mounting that for at least some deficits, initiation of rehabilitative strategies within the first 2 weeks of stroke is beneficial. Commencing intensive therapy in the first 24 h may be harmful.
BACKGROUND AND PURPOSE—A decrease in fractional anisotropy (FA) of the ipsilesional corticospinal tract (CST) distal to stroke lesions in the subacute (eg, 30 days) and chronic phase has been ...correlated with poor motor outcomes, but it is unclear whether FA values obtained within the acute stroke phase (here defined as 80 hours after onset) can predict later outcome.
METHODS—Fifty-eight patients underwent an assessment of motor impairment in the acute phase and at 3 months using the upper extremity Fugl-Meyer assessment. FA values, obtained within 80 hours after stroke onset, were determined in 2 regions of interestcerebral peduncle and a stretch of the CST caudal to each stroke lesion (nearest-5-slices).
RESULTS—The FA laterality index for the cerebral peduncle-regions of interest was a poor predictor of 3-month outcome (R=0.044; P=0.137), whereas the slope over the FA laterality index of the nearest-5-slices showed a relatively weak but significant prediction (R=0.11; P=0.022) with the affected side having lower FA values. Initial upper extremity Fugl-Meyer (R=0.69; P<0.001) and the weighted CST lesion load (R=0.71; P<0.001) were strong predictors of 3-month outcome. In multivariate analyses, controlling for initial upper extremity Fugl-Meyer, weighted CST lesion load, and days-of-therapy, neither the FA laterality index of the cerebral peduncle nor the slope over the FA laterality index of the nearest-5-slices significantly contributed to the prediction of 86% of the variance in the upper extremity Fugl-Meyer at 3 months.
CONCLUSIONS—FA reductions of the CST can be detected near the ischemic lesion in the acute stroke phase, but offer minimal predictive value to motor outcomes at 3 months.
In this study, a broad range of parameter combinations (laser power: 100–400 W; scanning speed: 10–90 mm/s) were used to fabricate Ti-47Al-2Cr-2Nb alloy at the layer thickness of 100 μm by selective ...laser melting (SLM). The preparation of the TiAl-single track by SLM was prone not only to balling and irregularity but also to cracking. Although the optimized process parameters were used to fabricate TiAl specimens, many pores and cracks still existed and a low density was achieved. To understand the mechanism for the crack and pore formation, the connections among the cracks, pores, and the process parameters were investigated in addition to the variation in the crack propagation with an increase in the number of deposition layers. The results indicated that the cracks originated in the third layer, because of the accumulation of residual stresses and the changes in the composition of Ti-47Al-2Cr-2Nb deposition layers. Additionally, the frequency of cracks constantly increased with an increase in the number of deposition layers. Preheating the substrate to 200 °C improved the degree of cracking to a certain extent, as the initiation layer for the cracks increased from the third layer to the fifth layer. Despite the achieved improvement, it was not possible to produce crack-free specimens on the SLM machine used for this study. Finally, there was a good metallurgical bond between the Ti-6Al-4 V substrate and the Ti-47Al-2Cr-2Nb deposition layers that was free of pore and crack defects. These findings suggest that using SLM to fabricate Ti-6Al-4 V/TiAl intermetallic laminate composites may potentially eliminate cracking and improve the properties of TiAl alloys.
•Low density Ti-47Al-2Cr-2Nb parts were fabricated by SLM.•Crack formation was related to process parameters in addition to the number of deposition layers.•Preheating the substrate to 200 °C partially mitigated cracking.•There was a good metallurgical bond between Ti-6Al-4 V substrate and Ti-47Al-2Cr-2Nb deposition layers.
Despite being the gold standard technique for stroke assessment, conventional diffusion MRI provides only partial information about tissue microstructure. Diffusional kurtosis imaging is an advanced ...diffusion MRI method that yields, in addition to conventional diffusion information, the diffusional kurtosis, which may help improve characterization of tissue microstructure. In particular, this additional information permits the description of white matter (WM) in terms of WM-specific diffusion metrics. The goal of this study is to elucidate possible biophysical mechanisms underlying ischemia using these new WM metrics.
We performed a retrospective review of clinical and diffusional kurtosis imaging data of 44 patients with acute/subacute ischemic stroke. Patients with a history of brain neoplasm or intracranial hemorrhages were excluded from this study. Region of interest analysis was performed to measure percent change of diffusion metrics in ischemic WM lesions compared with the contralateral hemisphere.
Kurtosis maps exhibit distinct ischemic lesion heterogeneity that is not apparent on apparent diffusion coefficient maps. Kurtosis metrics also have significantly higher absolute percent change than complementary conventional diffusion metrics. Our WM metrics reveal an increase in axonal density and a larger decrease in the intra-axonal (Da) compared with extra-axonal diffusion microenvironment of the ischemic WM lesion.
The well-known decrease in the apparent diffusion coefficient of WM after ischemia is found to be mainly driven by a significant drop in the intra-axonal diffusion microenvironment. Our results suggest that ischemia preferentially alters intra-axonal environment, consistent with a proposed mechanism of focal enlargement of axons known as axonal swelling or beading.
Urinary tract infection (UTI) is one of the most common infections seen in patients hospitalized for acute stroke, resulting in greater utilization of hospital resources in addition to patient ...discomfort. Although post-stroke infections (PSIs) are commonly referenced for interference with stroke recovery as well as associations with worse clinical outcome, factors associated specifically with UTI after stroke remain unclear.
To provide a comprehensive narrative synthesis covering literature published with results specific to the topic of UTI in stroke patients.
Literature review was performed searching the keywords “stroke” and “urinary tract infection” in Pubmed. All manuscripts published in English were appraised for information relevant to UTI in stroke patients. Applicable content was obtained, synthesized, and summarized.
Post-stroke UTI is found to be associated with prolongation of hospital length of stay (LOS), discharge to a Care Home, and increased medical care costs. This process possibly reflects the consequences of greater stroke severity and clinical courses requiring urinary catheterization in hospitalized patients. However, UTI does not share an independent association with long-term clinical outcomes including morbidities and mortality.
A narrative review was performed, including the following topics: classifications and epidemiology, pathogenesis, clinical features, and future directions. The heterogeneous nature of reports on UTI in stroke patients remains as a major limitation in literature.
•Stroke severity plays a large role in developing urinary tract infections.•Urinary tract infections after stroke may prolong length of stay and increase costs.•Post-stroke urinary tract infection does not significantly impact long term outcome.
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