Effects of Stroke on the Autonomic Nervous System

Examining the association between balance self-efficacy and virtual balance performance in individuals with stroke: a cross-sectional study

BACKGROUND

Balance self-efficacy is a strong predictor of fall risk after stroke and is related to performance on balance and walking tests. The use of telerehabilitation for delivering stroke rehabilitation has increased in recent years and there is a need to adapt common clinical assessments to be administered in virtual formats, but the association between balance self-efficacy and virtually administered clinical tests of balance performance has yet to be established. This study examined the association between the Activities-specific Balance Confidence (ABC) Scale and virtually administered Timed Up and Go (TUG), Tandem Stand, and Functional Reach tests (FRT) in individuals with stroke.

METHODS

This was a secondary analysis of baseline data from two telerehabilitation trials with individuals with stroke. All assessments were administered by trained physical therapists through videoconferencing software. Multivariate regression analyses were used to examine the associations between the ABC scale and TUG test, Tandem Stand test, and FRT, adjusted for age and number of comorbidities.

RESULTS

Data from 51 participants (n = 11 female, median age = 64 [IQR: 18] years, 9.3 ± 4.6 months poststroke) were analyzed. The ABC scores were associated with TUG (R2 = 0.56, F(3,47) = 20.26, p < 0.01), but not Tandem Stand (R2 = 0.18, F(5,45) = 1.93, p = 0.11) or FRT (R2 = 0.14, F(3,47) = 2.55, p = 0.07) tests.

CONCLUSION

We observed associations between the ABC scores and virtual TUG, but not with Tandem Stand or FRT, which may be attributed to the context-specificity of balance self-efficacy. As virtual administration of outcomes assessments becomes part of common practice in stroke rehabilitation, our study supports the use of virtually administered TUG in stroke.

Targeting brain-peripheral immune responses for secondary brain injury after ischemic and hemorrhagic stroke

The notion that the central nervous system is an immunologically immune-exempt organ has changed over the past two decades, with increasing evidence of strong links and interactions between the central nervous system and the peripheral immune system, both in the healthy state and after ischemic and hemorrhagic stroke. Although primary injury after stroke is certainly important, the limited therapeutic efficacy, poor neurological prognosis and high mortality have led researchers to realize that secondary injury and damage may also play important roles in influencing long-term neurological prognosis and mortality and that the neuroinflammatory process in secondary injury is one of the most important influences on disease progression. Here, we summarize the interactions of the central nervous system with the peripheral immune system after ischemic and hemorrhagic stroke, in particular, how the central nervous system activates and recruits peripheral immune components, and we review recent advances in corresponding therapeutic approaches and clinical studies, emphasizing the importance of the role of the peripheral immune system in ischemic and hemorrhagic stroke.

The role of gut microbiota in cerebrovascular disease and related dementia

In recent years, increasing evidence suggests that commensal microbiota may play an important role not only in health but also in disease including cerebrovascular disease. Gut microbes impact physiology, at least in part, by metabolizing dietary factors and host-derived substrates and then generating active compounds including toxins. The purpose of this current review is to highlight the complex interplay between microbiota, their metabolites. and essential functions for human health, ranging from regulation of the metabolism and the immune system to modulation of brain development and function. We discuss the role of gut dysbiosis in cerebrovascular disease, specifically in acute and chronic stroke phases, and the possible implication of intestinal microbiota in post-stroke cognitive impairment and dementia, and we identify potential therapeutic opportunities of targeting microbiota in this context. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

The Association Between Dehydration and the Prognosis of Sudden Sensorineural Hearing Loss

Background

There is an urgent need to identify undetermined risk factors for sudden sensorineural hearing loss (SSNHL) for the development of effective treatment strategies. SSNHL is likely associated with vascular insufficiency; however, no study has evaluated the relationship between dehydration and SSNHL.

Objective

This study aimed to investigate the role of dehydration in the development and prognosis of sudden sensorineural hearing loss.

Study Design

Retrospective case-control study.

Setting

Secondary referral hospital.

Patients and Interventions

This was a comparative study that compared dehydration parameters between healthy subjects without SSNHL (n = 94) and patients with SSNHL (n = 94). The study also evaluated the effect of dehydrated conditions on the prognosis of SSNHL.

Main Outcome Measures

We compared dehydration parameters, such as the blood urea nitrogen-to-creatinine ratio (BUN/Cre) and plasma osmolality (Posm), between matched healthy subjects without SSNHL and patients with SSNHL. To evaluate the effect of dehydrated conditions on the SSNHL prognosis, the SSNHL patients were divided into 2 groups based on the cutoff value obtained from the receiver operating characteristic analysis: hydrated (n = 50; BUN/Cre <21.4) and dehydrated (n = 44; BUN/Cre ≥21.4) groups. Subsequently, the severity and prognosis of SSNHL were analyzed.

Results

The dehydration parameters, BUN/Cre and Posm, were significantly higher in patients with SSNHL than in healthy subjects. The initial hearing levels and SSNHL grades were worse in the dehydrated group than in the hydrated group. Moreover, a dehydrated condition (BUN/Cre ≥21.4) was associated with a poor SSNHL prognosis in all models of the multiple logistic regression analysis.

Conclusions

The dehydration parameters of BUN/Cre and Posm were higher in patients with SSNHL than in healthy subjects. Additionally, a dehydrated condition (BUN/Cre ≥21.4) was an independent prognostic factor for SSNHL. Level of evidence: Level 4.

Research on atrial fibrillation mechanisms and prediction of therapeutic prospects: focus on the autonomic nervous system upstream pathways

Atrial fibrillation (AF) is the most common clinical arrhythmia disorder. It can easily lead to complications such as thromboembolism, palpitations, dizziness, angina, heart failure, and stroke. The disability and mortality rates associated with AF are extremely high, significantly affecting the quality of life and work of patients. With the deepening of research into the brain-heart connection, the link between AF and stroke has become increasingly evident. AF is now categorized as either Known Atrial Fibrillation (KAF) or Atrial Fibrillation Detected After Stroke (AFDAS), with stroke as the baseline. This article, through a literature review, briefly summarizes the current pathogenesis of KAF and AFDAS, as well as the status of their clinical pharmacological and non-pharmacological treatments. It has been found that the existing treatments for KAF and AFDAS have limited efficacy and are often associated with significant adverse reactions and a risk of recurrence. Moreover, most drugs and treatment methods tend to focus on a single mechanism pathway. For example, drugs targeting ion channels primarily modulate ion channels and have relatively limited impact on other pathways. This limitation underscores the need to break away from the "one disease, one target, one drug/measurement" dogma for the development of innovative treatments, promoting both drug and non-drug therapies and significantly improving the quality of clinical treatment. With the increasing refinement of the overall mechanisms of KAF and AFDAS, a deeper exploration of physiological pathology, and comprehensive research on the brain-heart relationship, it is imperative to shift from long-term symptom management to more precise and optimized treatment methods that are effective for almost all patients. We anticipate that drugs or non-drug therapies targeting the central nervous system and upstream pathways can guide the simultaneous treatment of multiple downstream pathways in AF, thereby becoming a new breakthrough in AF treatment research.

Time-varying information measures: an adaptive estimation of information storage with application to brain-heart interactions

Network Physiology is a rapidly growing field of study that aims to understand how physiological systems interact to maintain health. Within the information theory framework the information storage (IS) allows to measure the regularity and predictability of a dynamic process under stationarity assumption. However, this assumption does not allow to track over time the transient pathways occurring in the dynamical activity of a physiological system. To address this limitation, we propose a time-varying approach based on the recursive least squares algorithm (RLS) for estimating IS at each time instant, in non-stationary conditions. We tested this approach in simulated time-varying dynamics and in the analysis of electroencephalographic (EEG) signals recorded from healthy volunteers and timed with the heartbeat to investigate brain-heart interactions. In simulations, we show that the proposed approach allows to track both abrupt and slow changes in the information stored in a physiological system. These changes are reflected in its evolution and variability over time. The analysis of brain-heart interactions reveals marked differences across the cardiac cycle phases of the variability of the time-varying IS. On the other hand, the average IS values exhibit a weak modulation over parieto-occiptal areas of the scalp. Our study highlights the importance of developing more advanced methods for measuring IS that account for non-stationarity in physiological systems. The proposed time-varying approach based on RLS represents a useful tool for identifying spatio-temporal dynamics within the neurocardiac system and can contribute to the understanding of brain-heart interactions.

Stroke-heart syndrome: A case report and mini literature review

Despite the fact that cardiac troponin (cTn) elevation is commonly seen in the acute phase of ischemic stroke, investigating its etiology represents a challenge for healthcare practitioners. Therefore, we describe the case of an 86-year-old woman with dyspnea and cTn-elevation within the first days following acute ischemic stroke and discuss potential differential diagnoses and diagnostic dilemmas.

Dynamic changes of resting state functional network following acute ischemic stroke

Stroke, the second common cause of death in the world, is commonly considered to the well-known phenomenon of diaschisis. After stroke, regions far from the lesion can show altered neural activity. However, the comprehensive treatment recovery mechanism of acute ischemic stroke remains unclear. This study aims to investigate the impact of comprehensive treatment on resting state brain functional connectivity to reveal the therapeutic mechanism through a three time points study design. Twenty-one acute ischemic stroke patients and twenty matched healthy controls (HC) were included. Resting state functional magnetic resonance imaging (fMRI) and clinical evaluations were assessed in three stages: baseline (less than 72hours after stroke onset), post-first month and post-third month. Amplitude of low-frequency fluctuations (ALFF) and Independent component analysis (ICA) were conducted. We found: 1) stroke patients had decreased ALFF in the right cuneus (one of the important parts of the visual network). After three months, ALFF increased to the normal level; 2) the decreased functional connectivity in the right cuneus within the visual network and restored three months after onset. However, the decreased functional connectivity in the right precuneus within the default mode network restored one month after onset; 3) a significant association was found between the clinical scale score change over time and improvement in the cuneus and precuneus functional connectivity. Our results demonstrate the importance of the cuneus and precuneus within the visual network and default mode network in stroke recovery. These findings suggest that the different restored patterns of neural functional networks may contribute to the neurological function recovery. It has potential applications from stroke onset through rehabilitation because different rehabilitation phase corresponds to specific strategies.

CNS-peripheral immune interactions in hemorrhagic stroke

Stroke is a sudden and rapidly progressing ischemic or hemorrhagic cerebrovascular disease. When stroke damages the brain, the immune system becomes hyperactive, leading to systemic inflammatory response and immunomodulatory disorders, which could significantly impact brain damage, recovery, and prognosis of stroke. Emerging researches suggest that ischemic stroke-induced spleen contraction could activate a peripheral immune response, which may further aggravate brain injury. This review focuses on hemorrhagic strokes including intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) and discusses the central nervous system-peripheral immune interactions after hemorrhagic stroke induction. First, inflammatory progression after ICH and SAH is investigated. As a part of this review, we summarize the various kinds of inflammatory cell infiltration to aggravate brain injury after blood-brain barrier interruption induced by hemorrhagic stroke. Then, we explore hemorrhagic stroke-induced systemic inflammatory response syndrome (SIRS) and discuss the interactions of CNS and peripheral inflammatory response. In addition, potential targets related to inflammatory response for ICH and SAH are discussed in this review, which may lead to novel therapeutic strategies for hemorrhagic stroke.

Optimization of electrical stimulation for the treatment of lower limb dysfunction after stroke: A systematic review and Bayesian network meta-analysis of randomized controlled trials

OBJECTIVE

To compare the treatment effect of five electrical stimulation methods commonly used in the treatment of stroke patients with lower limb dysfunction.

METHODS

We implemented a systematic search of 3915 studies published up to January 2023 from eight databases and two clinical trial registries. First, two independent reviewers critically evaluated trial eligibility according to the inclusion and exclusion criteria. Next, they selected and extracted data. Then, they assessed the risk of bias. Pairwise meta-analysis and Bayesian network meta-analysis were conducted to estimate the effectiveness and ranking of the five electrical stimulation methods.

RESULTS

A total of 33 trials with a final total of 2246 subjects were included in the analysis. By combining the comprehensive Rehabilitation Treatment (RT), the treatment effects of using five electrical stimulation methods were surperior to those of using RT only. In the meantime, RT+transcranial Direct Current Stimulation(tDCS) and RT+Functional Electrical Stimulation(FES) could be the optimal electric stimulation schemes for restoring lower limb motor function(SMD 8.35, 95%CI [3.05, 13.34]/ SMD 5.64, 95%CI [3.68, 7.56]), improving balance (SMD 9.80, 95%CI [0.67, 20.93]/ SMD 6.54, 95%CI [3.85, 10.95]) and activities of daily living(SMD 18.95, 95%CI [0.401, 36.9]/ SMD 15.47, 95%CI [7.89, 22.75]), and the treatment effects would be even better using RT+FES+tDCS combination.

CONCLUSION

tDCS and FES superior to other electrical stimulation methods based on RT in the treatment of lower limb dysfunction after stroke.

Assessment of dynamic cerebral autoregulation in near-infrared spectroscopy using short channels: A feasibility study in acute ischemic stroke patients

Introduction

In acute ischemic stroke, progressive impairment of cerebral autoregulation (CA) is frequent and associated with unfavorable outcomes. Easy assessment of cerebral blood flow and CA in stroke units bedside tools like near-infrared spectroscopy (NIRS) might improve early detection of CA deterioration. This study aimed to assess dynamic CA with multichannel CW-NIRS in acute ischemic stroke (AIS) patients compared to agematched healthy controls.

Methods

CA reaction was amplified by changes in head of bed position. Long- and short channels were used to monitor systemic artery pressure- and intracranial oscillations simultaneously. Gain and phase shift in spontaneous low- and very low-frequency oscillations (LFO, VLFO) of blood pressure were assessed.

Results

A total of 54 participants, 27 with AIS and 27 age-matched controls were included. Gain was significantly lower in the AIS group in the LFO range (i) when the upper body was steadily elevated to 30. and (ii) after its abrupt elevation to 30°. No other differences were found between groups.

Discussion

This study demonstrates the feasibility of NIRS short channels to measure CA in AIS patients in one single instrument. A lower gain in AIS might indicate decreased CA activity in this pilot study, but further studies investigating the role of NIRS short channels in AIS are needed.

The gut-brain axis in ischemic stroke: its relevance in pathology and as a therapeutic target

The gut contains the largest reservoir of microorganisms of the human body, termed as the gut microbiota which emerges as a key pathophysiological factor in health and disease. The gut microbiota has been demonstrated to influence various brain functions along the “gut-brain axis”. Stroke leads to intestinal dysmotility and leakiness of the intestinal barrier which are associated with change of the gut microbiota composition and its interaction with the human host. Growing evidence over the past decade has demonstrated an important role of these post-stroke changes along the gut-brain axis to contribute to stroke pathology and be potentially druggable targets for future therapies. The impact of the gut microbiota on brain health and repair after stroke might be attributed to the diverse functions of gut bacteria in producing neuroactive compounds, modulating the host’s metabolism and immune status. Therefore, a better understanding on the gut-brain axis after stroke and its integration in a broader concept of stroke pathology could open up new avenues for stroke therapy. Here, we discuss current concepts from preclinical models and human studies on the bi-directional communication along the microbiota-gut-brain axis in stroke.

Relationship between heart rate variability and cognitive function in patients with enlarged perivascular space

Objective

To explore the relationship between heart rate variability (HRV), the brain distribution of enlarged perivascular space (EPVS), and cognitive impairment in patients with EPVS.

Materials and methods

The clinical and imaging data of 199 patients with EPVS were retrospectively analyzed. EPVS load in the basal ganglia (BG) and centrum semiovale (CS) regions were assessed using the Potter’s method. Cognitive function was evaluated using the Montreal Cognitive Assessment Scale. A logistic regression model was used to analyze the relationship between HRV, the brain distribution of EPVS and cognitive function in patients with EPVS. A receiver operating characteristic curve was used to assess the predictive value of HRV for cognitive function in patients with EPVS.

Results

Of the 199 patients, 27 and 42 presented with severe BG-EPVS and cognitive impairment, respectively. Significant differences were observed in the root mean square of successive differences of normal-normal (NN) intervals for period of interest (rMSSD), the percentage of adjacent NN intervals greater than 50 ms (PNN50), and the ratio of low-frequency power (LF) to high-frequency power (HF) between the mild and severe BG-EPVS groups (P &lt; 0.05). Patients who presented with and without cognitive impairment differed significantly in the standard deviation of NN intervals (SDNN), rMSSD, PNN50, total power, LF, and LF/HF (P &lt; 0.05). rMSSD (odds ratio [OR] 0.871, 95% confidence interval [CI] 0.768–0.988) and LF/HF (OR 3.854, 95% CI 1.196–12.419) were independent influencing factors of BG-EPVS, and rMSSD (OR 0.936, 95% CI 0.898–0.976) was an independent influencing factor of cognitive impairment in patients with EPVS. The optimal cut-off point was 0.312, with an area under the curve of 0.795 (95% CI 0.719–0.872) for predicting cognitive impairment in patients with EPVS by rMSSD.

Conclusion

Reduced HRV is involved in the pathophysiological mechanisms of the formation and development of BG-EPVS and is associated with cognitive impairment in patients with EPVS, independent of CS-EPVS. For patients with HRV changes but without autonomic nervous system symptoms, positive intervention may slow the occurrence or progression of EPVS and cognitive impairment in patients with EPVS.

Stroke-Heart Syndrome: Recent Advances and Challenges

After ischemic stroke, there is a significant burden of cardiovascular complications, both in the acute and chronic phase. Severe adverse cardiac events occur in 10% to 20% of patients within the first few days after stroke and comprise a continuum of cardiac changes ranging from acute myocardial injury and coronary syndromes to heart failure or arrhythmia. Recently, the term stroke–heart syndrome was introduced to provide an integrated conceptual framework that summarizes neurocardiogenic mechanisms that lead to these cardiac events after stroke. New findings from experimental and clinical studies have further refined our understanding of the clinical manifestations, pathophysiology, and potential long‐term consequences of the stroke–heart syndrome. Local cerebral and systemic mediators, which mainly involve autonomic dysfunction and increased inflammation, may lead to altered cardiomyocyte metabolism, dysregulation of (tissue‐resident) leukocyte populations, and (micro‐) vascular changes. However, at the individual patient level, it remains challenging to differentiate between comorbid cardiovascular conditions and stroke‐induced heart injury. Therefore, further research activities led by joint teams of basic and clinical researchers with backgrounds in both cardiology and neurology are needed to identify the most relevant therapeutic targets that can be tested in clinical trials.

Exploration on neurobiological mechanisms of the central–peripheral–central closed-loop rehabilitation

Central and peripheral interventions for brain injury rehabilitation have been widely employed. However, as patients’ requirements and expectations for stroke rehabilitation have gradually increased, the limitations of simple central intervention or peripheral intervention in the rehabilitation application of stroke patients’ function have gradually emerged. Studies have suggested that central intervention promotes the activation of functional brain regions and improves neural plasticity, whereas peripheral intervention enhances the positive feedback and input of sensory and motor control modes to the central nervous system, thereby promoting the remodeling of brain function. Based on the model of a central–peripheral–central (CPC) closed loop, the integration of center and peripheral interventions was effectively completed to form “closed-loop” information feedback, which could be applied to specific brain areas or function-related brain regions of patients. Notably, the closed loop can also be extended to central and peripheral immune systems as well as central and peripheral organs such as the brain–gut axis and lung–brain axis. In this review article, the model of CPC closed-loop rehabilitation and the potential neuroimmunological mechanisms of a closed-loop approach will be discussed. Further, we highlight critical questions about the neuroimmunological aspects of the closed-loop technique that merit future research attention.

Cognition impairment and risk of subclinical cardiovascular disease in older adults: The atherosclerosis risk in communities study

Background

Clinical cardiovascular disease (CVD) and cognition impairment are common and often coexist in aging populations, and CVD is associated with greater cognition impairment risk; however, the association between cognition impairment and CVD risk is inconsistent. It is unknown if pathways that contribute to CVD are caused by impaired cognition. We hypothesized that cognition impairment would be associated with greater subclinical CVD including subclinical myocardial damage [assessed by high-sensitivity cardiac troponin T (hs-cTnT)] and cardiac strain or dysfunction [assessed by N-terminal pro-B-type natriuretic peptide (NT-proBNP)].

Methods

This analysis included Atherosclerosis Risk in Communities Study (ARIC) participants who underwent global cognition z-score tests between 1991 and 1993. Cardiac biomarkers were measured from stored plasma samples collected between 1996 and 1999. Logistic regression models were used to determine the association of cognitive function with subclinical CVD risk.

Results

There were 558/9216 (6.1%) and 447/9097 (5.0%) participants with incident elevated hs-CTnT (≥14 ng/L) and NT-proBNP (≥300 pg/mL) levels, respectively. Comparing the lowest and highest quartiles of global cognition z-scores, a higher incidence of elevated hs-CTnT [odds ratio (OR) = 1.511, 95% confidence interval (CI): 1.093–2.088, P = 0.013] and NT-proBNP (OR = 1.929, 95% CI: 1.350–2.755, P &lt; 0.001) were observed, respectively. In structural equation modeling, the indirect effect of global cognition z-score on major adverse cardiac events was 42.1% (P &lt; 0.05).

Conclusion

Impairments in baseline cognitive function were associated with subclinical myocardial damage or wall strain. Although future studies are warranted to investigate the pathophysiological mechanisms behind these associations, our study suggests common pathways between cognitive and cardiac dysfunction.

Interactions between the Autonomic Nervous System and the Immune System after Stroke

Acute stroke is one of the leading causes of morbidity and mortality worldwide. Stroke-induced immune-inflammatory response occurs in the perilesion areas and the periphery. Although stroke-induced immunosuppression may alleviate brain injury, it hinders brain repair as the immune-inflammatory response plays a bidirectional role after acute stroke. Furthermore, suppression of the systemic immune-inflammatory response increases the risk of life-threatening systemic bacterial infections after acute stroke. Therefore, it is essential to explore the mechanisms that underlie the stroke-induced immune-inflammatory response. Autonomic nervous system (ANS) activation is critical for regulating the local and systemic immune-inflammatory responses and may influence the prognosis of acute stroke. We review the changes in the sympathetic and parasympathetic nervous systems and their influence on the immune-inflammatory response after stroke. Importantly, this article summarizes the mechanisms on how ANS regulates the immune-inflammatory response through neurotransmitters and their receptors in immunocytes and immune organs after stroke. To facilitate translational research, we also discuss the promising therapeutic approaches modulating the activation of the ANS or the immune-inflammatory response to promote neurologic recovery after stroke. © 2022 American Physiological Society. Compr Physiol 12:3665-3704, 2022.

Are beta blockers effective in preventing stroke associated infections? - a systematic review and meta-analysis

BACKGROUND

Excessive sympathoexcitation could lead to stroke associated infection. Inhibiting sympathetic excitation may reduce the infection risk after stroke. Thus, the present study aimed to determine the protective effect of beta blockers on stroke associated infection through systematic review and meta-analysis.

METHODS

A systematic search of multiple databases were performed up to February 2022. The included studies required beta blockers therapy in stroke patients and assessed the incidence of stroke-associated infections. Outcomes of interest included infections, pneumonia, urinary tract infection and sepsis. Random-effects model was used for analysis. Heterogeneity was evaluated using I2 statistics and publication bias was evaluated by the funnel plot.

RESULT

A total of 83 potentially relevant publications was identified in the initial search. Six studies met the inclusion criteria for meta-analysis. The risk of bias in the included articles satisfies the quality requirement of meta-analysis. No significant associations between beta blockers therapy and the prevention of stroke associated infection, stroke associated pneumonia and septicemia were found, However, subgroup analyses revealed an association between beta blockers treatment and the increased risk of post-stroke urinary tract infection or stroke associated pneumonia in some stroke patients (OR = 1.69 [1.33, 2.14], P < 0.0001; OR = 1.85 [1.51, 2.26], P < 0.0001).

CONCLUSION

Due to the lack of robust evidence, this meta-analysis may not support the preventive effect of beta blockers on stroke associated infection. But beta blockers treatment may be associated with development of post-stroke urinary tract infection and stroke associated pneumonia in some stroke patients.

The effect of a home-based coaching program on heart rate variability in subacute stroke patients: a randomized controlled trial

Autonomic imbalance in stroke is characterized by increased sympathetic activity and reduced vagal nerve activity. Physical activity could be a strategy to counteract autonomic control impairments after a stroke. The aim of the study was to evaluate the effect on heart rate variability of a 6-month coaching program in a home setting in subacute stroke patients. Eighty-four stroke patients participated in the study. They were randomly assigned to the experimental group or the control group. The intervention was a coaching program, consisting of physical activity, home visits and a weekly phone call. Patients were evaluated after hospital discharge (T0) and at the end of the 6-month period (T1). Heart rate variability measures were recorded in the supine and orthostatic positions. Time and frequency domain values were treated using Kubios. Distance on 6 minutes walking test (6MWT), Barthel and motricity index and modified functional ambulation categories were evaluated. No effects were found on time and frequency domain values in the supine and orthostatic positions in either group. Walking distance on 6MWT increased significantly between T0 and T1 in experimental group (377 ± 141-448 ± 140 m; P < 0.02) with no effects in control group (373.6 ± 150.6-394.6 ± 176.4 m). No other functional effects were found. A coaching program in a home setting had no effect on heart rate variability, probably due to time of recovery and exercise intensity. Future research is needed to understand the lack of changes in heart rate variability by physical activity in subacute stroke patients.

Interactions between remote ischemic conditioning and post-stroke sleep regulation

Sleep disturbances are common in patients with stroke, and sleep quality has a critical role in the onset and outcome of stroke. Poor sleep exacerbates neurological injury, impedes nerve regeneration, and elicits serious complications. Thus, exploring a therapy suitable for patients with stroke and sleep disturbances is imperative. As a multi-targeted nonpharmacological intervention, remote ischemic conditioning can reduce the ischemic size of the brain, improve the functional outcome of stroke, and increase sleep duration. Preclinical/clinical evidence showed that this method can inhibit the inflammatory response, mediate the signal transductions of adenosine, activate the efferents of the vagal nerve, and reset the circadian clocks, all of which are involved in sleep regulation. In particular, cytokines tumor necrosis factor α (TNFα) and adenosine are sleep factors, and electrical vagal nerve stimulation can improve insomnia. On the basis of the common mechanisms of remote ischemic conditioning and sleep regulation, a causal relationship was proposed between remote ischemic conditioning and post-stroke sleep quality.

Mechanism of Action of Dengzhan Shengmai in Regulating Stroke from an Inflammatory Perspective: A Preliminary Analysis of Network Pharmacology

Stroke is a complicated disease with an increasing incidence and a very high mortality rate. A classical Chinese herbal medicine, Dengzhan Shengmai (DZSM), has shown to have therapeutic effects on stroke; however, its chemical basis and molecular mechanism are still unclear. In this study, a systems biology approach was applicable to elucidate the underlying mechanism of action of DZSM on stroke. All the compounds were obtained from databases, and pendant-related targets were obtained from various data platforms, including the TCM Systematic Pharmacology (TCMSP) database, TCM Integrated Database (TCMIP), High Throughput Experimental Reference Database (HERB), Comparative Toxicogenomics Database (CTD), SwissTargetPredicition, and SymMap, The Human Gene Database (GENECARD) and Comparative Toxicogenomics Database (CTD) were used for stroke disease target data, followed by network pharmacology analysis to predict the potential effect of DZSM on stroke. Animal experiments were intended to validate the underlying mechanisms. A total of 846 chemical components were compiled for the targets of DZSM drug, and quercetin, kaempferol, and Wuweizisu C are the highest chemical components compiled from DZSM. Overlapping with 375 disease-specific targets and 149 core targets, the core targets include TNF, IL-6, ALB, and AKT1, which are shown to regulate the disease process from an anti-inflammatory perspective. 198 enrichment messages were obtained by KEGG enrichment analysis, and we believe that the role of the AGE-RAGE signaling pathway in diabetic complications, TNF signaling pathway, and IL-17 signaling pathway is more important. Based on rat experiments, we also demonstrated that DZSM could effectively modulate the inflammation level of brain infarct tissues and effectively alleviate behavioral characteristics. Grouped together, our study suggests that the combination of network pharmacology prediction and experimental validation can provide a useful tool to describe the molecular mechanisms of DZSM in Chinese medicine (TCM).

Mean Platelet Volume as a Potential Marker of Large Vessel Occlusion and Predictor of Outcome in Acute Ischemic Stroke Patients Treated with Reperfusion Therapy

(1) Background: An early diagnosis of a large vessel occlusion (LVO) is crucial in the management of the acute ischemic stroke (AIS). The laboratory predictors of LVO and a stroke outcome remain unknown. We have hypothesized that high MPV—a surrogate marker of the activated platelet—may be associated with LVO, and it may predict a worse AIS outcome. (2) Methods: This was a retrospective study of 361 patients with AIS who were treated with thrombolysis (tPA, 65.7%) and/or mechanical thrombectomy (MT, 34.3%) in a tertiary Stroke Center between 2011 and 2019. (3) Results: The mean MPV in the cohort was 9.86 ± 1.5 fL (1st–4th quartiles: <8.8, >10.80 fL). Patients in the 4th quartile compared to the 1st had a significantly (p < 0.01) more often incidence of an LVO related stroke (75% vs. 39%) and a severe stroke manifestation with a higher RACE score (5.2 ± 2.8 vs. 3.3 ± 2.4), NIHSS at baseline (mean ± SD, 14 ± 6.5 vs. 10.9 ± 5.2), and NIHSS at discharge (6.9 ± 7 vs. 3.9 ± 3.6). A multivariate analysis revealed that quartiles of MPV (OR 1.4; 95%CI 1.2–1.8) significantly predicted an LVO stroke, also after the adjustment for RACE < 5 (OR 1.4; 95%CI 1.08–1.89), but MPV quartiles did not predict a favorable stroke outcome (mRS ≤ 2) (OR 0.89; 95%CI 0.7–1.13). (4) Conclusion: Our data suggest that MPV is an independent predictor of LVO in patients with an acute ischemic stroke.

Prolonged Elevation of Arterial Stiffness Following Peak Aerobic Exercise in Individuals With Chronic Stroke

Background

Stroke is a highly disabling condition and is the second leading cause of death globally. Engaging in aerobic exercise is important for the prevention of a recurrent stroke through improving markers of cardiovascular health such as blood pressure and arterial stiffness. While higher intensities of aerobic exercise generally elicit greater cardioprotective effects, little is known about the acute cardiovascular effects of a single session of high intensity aerobic exercise in people with stroke. The objective of this study was to model the recovery of arterial stiffness (carotid-femoral pulse wave velocity, cfPWV), heart rate and blood pressure following peak intensity aerobic exercise in individuals with chronic stroke.

Methods

Ten participants with chronic stroke (mean ± SD age = 56.9 ± 11.8 years, median [IQR] years post-stroke = 2.9 [1.9]) performed a symptom-limited cardiopulmonary exercise test (CPET) on a recumbent stepper. Before the CPET, resting cfPWV, heart rate and blood pressure were measured. Immediately following the CPET, all outcomes were measured again continuously for 20 min to use all available observations (n = 245 observations) and capture any potential non-linear changes. Mixed model analyses were then applied to model post-exercise changes of cfPWV, heart rate and blood pressure.

Results

Carotid-femoral pulse wave velocity was increased from rest following the CPET (9.0 ± 0.53 to 9.9 ± 0.52 m/s, p < 0.001) and remained elevated for 20 min into post-exercise recovery, independent of heart rate (p = 0.001). Heart rate also increased from baseline (71.2 ± 3.2 to 77.4 ± 3.1 bpm, p < 0.001) and remained elevated for 10 min post-exercise (p < 0.001). Finger systolic blood pressure was reduced from rest (117.3 ± 4.7 to 111.8 ± 4.6 mmHg, p < 0.001) and remained reduced for 15 min after exercise (p < 0.001). There were no significant differences in finger diastolic or mean arterial pressures from rest.

Conclusion

This was the first study to capture continuous changes in cfPWV following peak aerobic exercise in any clinical population. The present study revealed that cfPWV is elevated for 20 min after peak aerobic exercise in individuals with stroke, which was independent of heart rate. These findings suggest there may be autonomic imbalances in large arteries following peak intensity aerobic exercise in individuals with stroke.

Restoring neuro-immune circuitry after brain and spinal cord injuries

Neuro-immune interactions are essential for our body's defense and homeostasis. Anatomical and physiological analyses have shown that the nervous system comprises multiple pathways that regulate the dynamics and functions of immune cells, which are mainly mediated by the autonomic nervous system and adrenal signals. These are disturbed when the neurons and circuits are damaged by diseases of the central nervous system (CNS). Injuries caused by stroke or trauma often cause immune dysfunction by abrogation of the immune-regulating neural pathways, which leads to an increased risk of infections. Here, I review the structures and functions of the neural pathways connecting the brain and the immune system, and the neurogenic mechanisms of immune dysfunction that emerge after CNS injuries. Recent technological advances in manipulating specific neural circuits have added mechanistic aspects of neuro-immune interactions and their dysfunctions. Understanding the neural bases of immune control and their pathological processes will deepen our knowledge of homeostasis and lead to the development of strategies to cure immune deficiencies observed in various CNS disorders.

Cardiovascular autonomic dysfunction after stroke

Strokes are the paradigmatic example of the sudden impairment of the cerebral regulation of cardiac autonomic regulation. Although several aspects of dysautonomic cardiovascular regulation post stroke remain unanswered, there has been a wealth of research in this area in the last decade. In this article, we present a state-of-the-art review on the anatomical and functional organization of cardiovascular autonomic regulation, and the pathophysiology, incidence, time course, diagnosis, clinical aspects, prognosis, and management of post-stroke cardiovascular autonomic dysfunction.

An Inhomogeneous Point-process Model for the Assessment of the Brain-to-Heart Functional Interplay: a Pilot Study

We propose a novel computational framework for the estimation of functional directional brain-to-heart interplay in an instantaneous fashion. The framework is based on inhomogeneous point-process models for human heartbeat dynamics and employs inverse-Gaussian probability density functions characterizing the timing of R-peak events. The instantaneous estimation of the functional directional coupling is based on the definition of point-process transfer entropy, which is here retrieved from heart rate variability (HRV) and Electroencephalography (EEG) power spectral series gathered from 12 healthy subjects undergoing significant sympathovagal changes induced by a cold-pressor test. Results suggest that EEG oscillations dynamically influence heartbeat dynamics with specific time delays in the 30-60s and 90-120s ranges, and through a functional activity over specific cortical regions.

Decreased LF/HF ratio is associated with worse outcomes in patients who received mechanical thrombectomy under general anesthesia for emergent large vessel occlusion: a retrospective study

BACKGROUND AND PURPOSE

We aimed to determine whether heart rate variability (HRV) was correlated to long-term outcome in patients who received mechanical thrombectomy (MT) under general anesthesia for emergent large vessel occlusion (ELVO).

METHODS

Data from 106 patients receiving MT under general anesthesia to treat ELVO between January 1, 2017 and December 31, 2019 were collected in a multicenter chart review. Univariate analysis, Chi-square test, and bivariate logistic regression were performed to assess the correlations between preoperative risk factors such as HRV and long-term outcome (as indicated by the modified Rankin score [mRS] at 90 days after MT).

RESULTS

Bivariate logistic regression revealed that decreased LF/HF (low frequency/high frequency in HRV) ratio was correlated with unfavorable functional outcome as indicated by mRS ≥ 2 (odds ratio [OR], 0.650; 95% confidence interval [CI], 0.157-0.839; p = 0.018), and functionally dependent outcome as indicated by mRS ≥ 3 (OR, 0.704; 95% CI, 0.360-0.914; p = 0.021). It was also found that ELVO in the right anterior circulation was correlated with lower LF/HF ratio, as compared with ELVO in the contralateral side (p < 0.05).

CONCLUSION

Our retrospective study demonstrated that worse outcome in patients with ELVO who received MT under general anesthesia induced autonomic changes and that decreased LF/HF ratio.

Lacunar stroke and heart rate variability during sleep

OBJECTIVE

Autonomic instability during sleep can influence the risk of cerebrovascular diseases. In this study, we performed a polygraphy to evaluate, heart rate variability (HRV) in a group of patients with lacunar stroke that is a condition at high risk of recurrence.

METHODS

Twenty-one lacunar stroke patients were enrolled one month after stroke occurrence. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). The presence of common sleep disorders and autonomic changes during the night was investigated by a polygraphy monitoring. Results were compared with those obtained in a group of 21 healthy subjects.

RESULTS

Patients and controls were similar for age, sex distribution and main cardiovascular risk factors with the exception of the body mass index. Significant differences were detected for all polysomnographic (PSG) parameters and for the PSQI score. By considering HRV values, patients with pathologic values (12 patients, HRV>2) showed significantly higher values in BMI (31 ± 2.9 vs. 26.6 ± 3.6, p = 0.006) and PSQI scores (7.9 ± 2.6 vs. 4.2 ± 1.9) with respect to patients with normal HRV values (nine patients, HRV≤2).

CONCLUSIONS

The results of this study suggest that the prevalence of nocturnal autonomic dysfunction is high in lacunar stroke patients even in the absence of the commonest sleep-related disorders. An abnormal HRV may contribute to increase the risk of stroke recurrence. Based on our results, the indication to polygraphy in patients with lacunar stroke should be carefully considered.

The Local and Peripheral Immune Responses to Stroke: Implications for Therapeutic Development

The immune response to stroke is an exciting target for future stroke therapies. Stroke is a leading cause of morbidity and mortality worldwide, and clot removal (mechanical or pharmacological) to achieve tissue reperfusion is the only therapy currently approved for patient use. Due to a short therapeutic window and incomplete effectiveness, however, many patients are left with infarcted tissue that stimulates inflammation. Although this is critical to promote repair, it can also damage surrounding healthy brain tissue. In addition, acute immunodepression and subsequent infections are common and are associated with worse patient outcomes. Thus, the acute immune response is a major focus of researchers attempting to identify ways to amplify its benefits and suppress its negative effects to improve short-term recovery of patients. Here we review what is known about this powerful process. This includes the role of brain resident cells such as microglia, peripherally activated cells such as macrophages and neutrophils, and activated endothelium. The role of systemic immune activation and subsequent immunodepression in the days after stroke is also discussed, as is the chronic immune responses and its effects on cognitive function. The biphasic role of inflammation, as well as complex timelines of cell production, differentiation, and trafficking, suggests that the relationship between the acute and chronic phases of stroke recovery is complex. Gaining a more complete understanding of this intricate process by which inflammation is initiated, propagated, and terminated may potentially lead to therapeutics that can treat a larger population of stroke patients than what is currently available. The immune response plays a critical role in patient recovery in both the acute and chronic phases after stroke. In patients, the immune response can be beneficial by promoting repair and recovery, and also detrimental by propagating a pro-inflammatory microenvironment. Thus, it is critical to understand the mechanisms of immune activation following stroke in order to successfully design therapeutics.

The association of genetic polymorphisms in CYP1A2, UGT1A4, and ABCB1 with autonomic nervous system dysfunction in schizophrenia patients treated with olanzapine

BACKGROUND

Use of the antipsychotic drug olanzapine by patients with schizophrenia is associated with autonomic nervous system (ANS) dysfunction. It is presumed that there are interindividual differences in ANS dysfunction that correspond to pharmacogenetics. In this study, we investigated whether genetic polymorphisms in ABCB1, CYP1A2, and UGT1A4 are associated with this observed ANS dysfunction.

METHODS

A total of 91 schizophrenia patients treated with olanzapine monotherapy participated in this study. A power spectral analysis of heart rate variability was used to assess ANS activity. The TaqMan system was used to genotype seven single nucleotide polymorphisms (SNPs) in CYP1A2 (rs2069514 and rs762551), UGT1A4 (rs2011425), and ABCB1 (rs1045642, rs1128503, rs2032582, rs2235048).

RESULTS

Sympathetic nervous activity was significantly higher in individuals with the UGT1A4 rs2011425 G allele than in those with the UGT1A4 rs2011425 non-G allele (sympathetic activity, p = .001). Furthermore, sympathetic nervous activity was also significantly associated with UGT1A4 rs2011425 genotype as revealed by multiple regression analysis (sympathetic activity, p = .008).

CONCLUSIONS

We suggest that the UGT1A4 rs2011425 polymorphism affects olanzapine tolerability because it is associated with the observed side effects of olanzapine in schizophrenia patients, namely sympathetic dysfunction.

Effects of Transcranial Direct Current Stimulation (tDCS) and Exercises Treadmill on Autonomic Modulation of Hemiparetic Patients Due To Stroke-Clinic Test, Controlled, Randomized, Double-Blind

Background: After a Stroke, there is an autonomic nervous system (ANS) changes. Transcranial Direct Current Stimulation (tDCS) can promote the reorganization of the affected circuits.

Objective: To evaluate the effects of tDCS applied before a session of physical activity on the treadmill, in the modulation of the autonomic nervous system of post-stroke patients.

Methodology: Cross-over study, were randomized 12 adult hemiparetic subjects in 2 groups, Group 1 (active tDCS before exercise on the treadmill) and Group 2 (sham tDCS before exercise on the treadmill). Stimulation times were 20 min; treadmill time was 20 min. The heart rate variability (HRV) and Variability of Systolic Blood Pressure (VSBP) were evaluated for 15 min, in 3 periods (pre and post tDCS and during exercise recovery on the treadmill).

Results: There was no difference in the VSBP and the HRV between the groups, compared with the baseline data; however, in the intragroup analysis, the parasympathetic modulation after active tDCS increased by 18% over baseline by the RMSSD with IC 95% (−7.85 to −0.34). In group 1, the post-tDCS active and post-exercise periods presented a value of variance above baseline, indicating a better prognosis. In group 2, there was a significant reduction of 38% of Variance values (p = 0.003) after tDCS sham.

Conclusion: tDCS does not generate immediate effects on HRV and VSBP, except for intragroup comparison, which has greater participation in parasympathetic modulation in the group receiving active tDCS.

Augmentation of peripheral lymphocyte-derived cholinergic activity in patients with acute ischemic stroke

Background

Brain ischemia activates the parasympathetic cholinergic pathway in animal models of human disease. However, it remains unknown whether activation of the cholinergic pathway impacts immune defenses and disease outcomes in patients with ischemic stroke. This study investigated a possible association between peripheral cholinergic activity, post-stroke infection, and mortality.

Methods

In this study, we enrolled 458 patients with acute ischemic stroke (< 24 h after onset), 320 patients with ischemic stroke on day 10, and 216 healthy subjects. Peripheral cholinergic activity, reflected by intracellular acetylcholine (ACh) content in human peripheral blood mononuclear cells (PBMCs), was determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Expression of acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) was measured by quantitative real-time PCR and western blot. Regression analyses were used to assess associations between peripheral cholinergic function and clinical outcomes.

Results

Within 24 h after the onset of acute ischemic stroke, there was a rapid increase in peripheral cholinergic activity that correlated with brain infarction volume (r = 0.67, P < 0.01). Specifically, lymphocyte-derived ACh levels were significantly higher in stroke patients with pneumonia (0.21 ± 0.02 ng/10⁶ PBMC versus 0.15 ± 0.01 ng/10⁶ PBMC, P = 0.03). Of note, lymphocytic AChE catalytic activity was significantly lower in these patients. One-year mortality was significantly greater in patients with higher intracellular ACh levels within the first 24 h after acute stroke.

Conclusions

Lymphocytes produced increased amounts of ACh in patients with acute stroke, and pneumonia was a likely result. The association between this enhanced cholinergic activity and increased risk of pneumonia/mortality suggests that increased cholinergic activity may contribute to fatal post-stroke infection.

Heart rate variability as predictive factor for sudden cardiac death

Sudden cardiac death (SCD) represents about 25% of deaths in clinical cardiology. The identification of risk factors for SCD is the philosopher's stone of cardiology and the identification of non-invasive markers of risk of SCD remains one of the most important goals for the scientific community.

The aim of this review is to analyze the state of the art around the heart rate variability (HRV) as a predictor factor for SCD.

HRV is probably the most analyzed index in cardiovascular risk stratification technical literature, therefore an important number of models and methods have been developed.

Nowadays, low HRV has been shown to be independently predictive of increased mortality in post- myocardial infarction patients, heart failure patients, in contrast with the data of the general population.

Contrariwise, the relationship between HRV and SCD has received scarce attention in low-risk cohorts. Furthermore, in general population the attributable risk is modest and the cost/benefit ratio is not always convenient.

The HRV evaluation could become an important tool for health status in risks population, even though the use of HRV alone for risk stratification of SCD is limited and further studies are needed.

Identification of key genes and upstream regulators in ischemic stroke

INTRODUCTION

Ischemic stroke (IS) causes severe neurological impairments and physical disabilities and has a high economic burden. Our study aims to identify the key genes and upstream regulators in IS by integrated microarray analysis.

METHODS

An integrated analysis of microarray studies of IS was performed to identify the differentially expressed genes (DEGs) in IS compared to normal control. Based on these DEGs, we performed the functional annotation and transcriptional regulatory network constructions. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the expression of DEGs.

RESULTS

From two Gene Expression Omnibus datasets obtained, we obtained 1526 DEGs (534 up-regulated and 992 down-regulated genes) between IS and normal control. The results of functional annotation showed that Oxidative phosphorylation and Alzheimer's disease were significantly enriched pathways in IS. Top four transcription factors (TFs) with the most downstream genes including PAX4, POU2F1, ELK1, and NKX2-5. The expression of six genes (ID3, ICAM2, DCTPP1, ANTXR2, DUSP1, and RGS2) was detected by qRT-PCR. Except for DUSP1 and RGS2, the other four genes in qRT-PCR played the same pattern with that in our integrated analysis.

CONCLUSIONS

The dysregulation of these six genes may involve with the process of ischemic stroke (IS). Four TFs (PAX4, POU2F1, ELK1 and NKX2-5) were concluded to play a role in IS. Our finding provided clues for exploring mechanism and developing novel diagnostic and therapeutic strategies for IS.

The effect of unilateral stroke on autonomic function in the term newborn

BACKGROUND

The mature cerebral cortex has a topographically organized influence on reflex autonomic centers of the brainstem and diencephalon and sympathetic activation coming primarily from the right hemisphere and parasympathetic activation from the left. In the term newborn, the maturational status of this central autonomic system remains poorly understood.

METHODS

Sixteen term newborns admitted to Children's National with unilateral middle cerebral artery (MCA) strokes (n = 8 left, n = 8 right) had archived continuous electrocardiograph (EKG) signals available. We compared stroke laterality and severity with indices of autonomic function, as measured by heart rate variability. We performed both time- and frequency-domain analyses on the R-R interval (RRi) over 24h of continuous EKG data at around 7 days of age.

RESULTS

Right MCA stroke significantly increased sympathetic tone, while left MCA stroke increased parasympathetic tone. Regardless of laterality, stroke severity was associated inversely with sympathetic tone and positively with parasympathetic tone. Surprisingly, injury to either insular region had no significant autonomic effect. Phenobarbital blood levels were positively associated with sympathetic tone and inversely related to parasympathetic tone.

CONCLUSION

Based on these findings, it is difficult to reconcile the functional topography of the central autonomic system in term newborns with that currently proposed for the normal mature brain. Further investigation is clearly needed.

Experimental ischaemic stroke induces transient cardiac atrophy and dysfunction

BACKGROUND

Stroke can lead to cardiac dysfunction in patients, but the mechanisms underlying the interaction between the injured brain and the heart are poorly understood. The objective of the study is to investigate the effects of experimental murine stroke on cardiac function and molecular signalling in the heart.

METHODS AND RESULTS

Mice were subjected to filament-induced left middle cerebral artery occlusion for 30 or 60 min or sham surgery and underwent repetitive micro-echocardiography. Left ventricular contractility was reduced early (24-72 h) but not late (2 months) after brain ischaemia. Cardiac dysfunction was accompanied by a release of high-sensitive cardiac troponin (hsTNT (ng/ml): d1: 7.0 ± 1.0 vs. 25.0 ± 3.2*; d3: 7.3 ± 1.1 vs. 52.2 ± 16.7*; d14: 5.7 ± 0.8 vs. 5.2 ± 0.3; sham vs. 60 min. MCAO; mean ± SEM; *p < 0.05); reduced heart weight (heart weight/tibia length ratio: d1: 6.9 ± 0.2 vs. 6.4 ± 0.1*; d3: 6.7 ± 0.2 vs. 5.8 ± 0.1*; d14: 6.7 ± 0.2 vs. 6.4 ± 03; sham vs. 60 min. MCAO; mean ± SEM; *p < 0.05); resulting from cardiomyocyte atrophy (cardiomyocyte size: d1: 12.8% ± 0.002**; d3: 13.5% ± 0.002**; 14d: 6.3% ± 0.003*; 60 min. MCAO vs. sham; mean ± SEM; **p < 0.01; *p < 0.05), accompanied by increased atrogin-1 and the E3 ubiquitin ligase murf-1. Net norepinephrine but not synthesis was increased, suggesting a reduced norepinephrine release or an increase of norepinephrine re-uptake, resulting in a functional denervation. Transcriptome analysis in cardiac tissue identified the transcription factor peroxisome proliferator-activated receptor gamma as a potential mediator of stroke-induced transcriptional dysregulation involved in cardiac atrophy.

CONCLUSIONS

Stroke induces a complex molecular response in the heart muscle with immediate but transient cardiac atrophy and dysfunction.

Surge of corticocardiac coupling in SHRSP rats exposed to forebrain cerebral ischemia

Sudden death is an important but underrecognized consequence of stroke. Acute stroke can disturb central control of autonomic function and result in cardiac dysfunction and sudden death. Previous study showed that bilateral common carotid artery ligation (BCCAL) in the spontaneously hypertensive stroke-prone rat strain (SHRSP) is a well-established model for forebrain ischemic sudden death. This study aims to investigate the temporal dynamic changes in electrical activities of the brain and heart and functional interactions between the two vital organs following forebrain ischemia. EEG and ECG signals were simultaneously collected from nine SHRSP and eight Wistar-Kyoto (WKY) rats. RR interval was analyzed to investigate the cardiac response to brain ischemia. EEG power and coherence (CCoh) analysis were conducted to study the cortical response. Corticocardiac coherence (CCCoh) and directional connectivity (CCCon) were analyzed to determine brain-heart connection. Heart rate variability (HRV) was analyzed to evaluate autonomic functionality. BCCAL resulted in 100% mortality in SHRSP within 14 h, whereas no mortality was observed in WKY rats. The functionality of both the brain and the heart were significantly altered in SHRSP compared with WKY rats after BCCAL. SHRSP, but not WKY rats, exhibited intermittent surge of CCCoh, which paralleled the elevated CCCon and reduced HRV, following the onset of ischemia until sudden death. Elevated brain-heart coupling invariably associated with the disruption of the autonomic nervous system and the risk of sudden death. This study may improve our understanding of the mechanism of forebrain ischemia-induced sudden death. NEW & NOTEWORTHY This study demonstrates a marked surge of corticocardiac coupling in rats dying from focal cerebral ischemia, consistent with our earlier data in rats exposed to fatal asphyxia. Since the bidirectional electrical signal coupling (corticocardiac coherence) and communication (corticocardiac connectivity) between the brain and the heart are only identified in dying animals, they could be used as potential biomarkers to predict the risk of sudden death.

Prevalence and factors associated with fast resting heart rate in hypertensive and normotensive patients

Background: Fast resting heart rate (RHR) is easily neglected in clinical practice of hypertension treatment.Aims: We aimed to investigate the prevalence of fast RHR and associated factors in hypertensive and normotensive individuals.Methods: We retrospectively analyzed data from two cross-sectional studies conducted in China. A total of 6763 hypertensive patients and 2807 age and sex-matched normotensive subjects with complete data on resting electrocardiogram and medical history were included. Fast RHR was defined as RHR > 85 bpm.Results: The prevalence of fast RHR was higher in hypertensive patients as compared with the normotensives (14.4% vs 7.1%, P < 0.01). In both hypertensive and normotensive subjects, fast RHR appeared as a "U-type" distribution as aging and a "inverted J type" trend as body mass index (BMI) increasing. Multivariate regression analysis showed that fast RHR was associated with age >65 or <25 years old (OR = 1.32, 95% CI 1.08-1.61), BMI <18.5 kg/m² (OR = 2.94, 95%CI 1.47-5.87) and hypercholesterolemia (OR = 1.30, 95%CI 1.10-1.53) in hypertensive patients. Fast RHR in the normotensives was associated with female (OR = 1.78, 95%CI 1.27-2.48), pre-hypertensive state (OR = 2.38, 95%CI 1.61-3.52), and rural area origin (OR = 1.50, 95%CI 1.01-2.42). Stroke and diabetes conferred closer relevance to fast RHR in both hypertensive (OR = 1.31, 95%CI 1.02-1.69 and OR 2.26, 95%CI 1.60-3.21) and normotensive individuals (OR = 2.67, 95%CI 1.36-5.21 and OR = 2.77, 95%CI 1.47-5.23).Conclusion: Fast RHR might be common in patients with hypertension. Prior stroke and diabetes history is common associated with fast RHR. Other factors associated with fast RHR seem to be different between hypertensive patients and normotensive subjects.Abbreviations: BMI: body mass index; CI: Confidence Interval; DBP: diastolic blood pressure; ECG: electrocardiogram; OR: odd ratio; RHR: resting heart rate; SBP: systolic blood pressure.

Tracking autonomic balance using an open-loop model of the arterial baroreflex

Blood pressure control is vital for maintaining adequate perfusion of the brain and other organs in the body across varying physiological demands, and the arterial baroreceptor reflex (baroreflex) is the major short-term blood pressure control loop mediated by the autonomic nervous system (ANS). Accurate quantitative models of the baroreflex would provide physiological insight and could allow for real-time tracking of ANS activity in clinical settings. In this work, we formulate a causal, parametric beat-to-beat model, relating systolic blood pressure (input) to heart rate (output). Model structure and parameterization are explicitly based on prior physiological insights of the response dynamics of the sympathetic and parasympathetic branches of the ANS. We analyze the model's ability to track changes in autonomic balance using data from 14 nonsmoking adult males, without any history of cardiopulmonary disease, subject to both pharmacological blockade and postural changes. Our results show that the model parameters faithfully track expected changes in autonomic balance resulting from changing posture ( P < 0.01) and sympathetic blockade ( P < 0.05), and in many cases, the model parameters are more sensitive to changes in autonomic activity and balance than autonomic indices derived from the power spectral density of heart rate variability. Overall, the contributions of this work further the goal of obtaining real-time quantitative assessment of the ANS.

Effects of transcranial direct current stimulation on walking ability after stroke: A systematic review and meta-analysis

BACKGROUND

As a promising technique, transcranial direct current stimulation (tDCS) has gained so much attention in its potential effects on functional recovery of lower limb following stroke. However, individual studies have yielded inconsistent or conflicting results.

OBJECTIVE

To investigate the efficacy and safety of tDCS for the functional recovery of lower limb following stroke reported in the randomized controlled trials by using a meta-analysis.

METHODS

MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science, CENTRAL, and Physiotherapy Evidence Database was comprehensively searched for randomized controlled trials published until April 2017 that investigated the effects of tDCS on lower limb function. Main outcomes included walking speed, walking endurance, mobility, balance function, muscle strength of lower limb and adverse events.

RESULTS

A total of 10 trials (n = 194) met the inclusion criteria. Meta-analysis demonstrated a significant effect of tDCS on mobility (SMD 0.44, 95% CI: 0.01 to 0.87, P = 0.04) and muscle strength of lower limb (SMD 1.54, 95% CI: 0.29 to 2.78, P = 0.02). No significant effects were found in walking speed (SMD 0.39, 95% CI: -0.06 to 0.85, P = 0.09), walking endurance (SMD 0.28, 95% CI: -0.28 to 0.84, P = 0.33) and balance function (SMD 0.44, 95% CI: -0.06 to 0.94, P = 0.08).

CONCLUSION

tDCS might have beneficial effects on improving mobility and muscle strength of lower limb among individuals with stroke. Future studies with larger sample sizes and an adequate follow-up period are needed.

Association between dysfunction of autonomic nervous system activity and mortality in schizophrenia

BACKGROUND

Patients with schizophrenia have a higher mortality risk than the general population. Additionally, the autonomic nervous system (ANS) activity of patients with schizophrenia is lower and more dysfunctional than that of the general population. Nonetheless, the association between ANS dysfunction and mortality in schizophrenia is unclear. The aim of this study was to investigate the association between ANS activity and mortality in schizophrenia and to evaluate the predictive values of heart rate variability for long-term survival.

METHODS

This study involves the 10-year follow-up of a sample population consisting of 59 Japanese inpatients with schizophrenia between 60 and 70 years of age from 2007 to 2016. The ANS activity of all patients was evaluated using heart rate variability in 2007.

RESULTS

Fifty-three participants could be followed up because they stayed in the hospital during the follow-up period. Of these patients, 11 died during follow-up. Their mean age at death was 70.55 ± 3.45 years. The parasympathetic activity of nonsurvivors was significantly lower than that of survivors, and multiple logistic regression analysis showed a significant association between death and parasympathetic activity.

CONCLUSION

We suggest that decreased parasympathetic activity could be associated with 10-year all-cause mortality in older schizophrenic patients.

Anticonvulsant effect of dipropofol by enhancing native GABA currents in cortical neurons in mice

Temporal lobe epilepsy (TLE), the most common pharmacoresistant focal epilepsy disorder, remains a major unmet medical need. Propofol is used as a short-acting medication for general anesthesia and refractory status epilepticus with issues of decreased consciousness and memory loss. Dipropofol, a derivative of propofol, has been reported to exert antioxidative and antibacterial activities. Here we report that dipropofol exerted anticonvulsant activity in a mouse model of kainic acid-induced seizures. Whole cell patch-clamp recordings of brain slices from the medial entorhinal cortex (mEC) revealed that dipropofol hyperpolarized the resting membrane potential and reduced the number of action potential firings, resulting in suppression of cortical neuronal excitability. Furthermore, dipropofol activated native tonic GABAA currents of mEC layer II stellate neurons in a dose-dependent manner with an EC50 value of 9.3 ± 1.6 μM (mean ± SE). Taken together, our findings show that dipropofol activated GABAA currents and exerted anticonvulsant activities in mice, thus possessing developmental potential for new anticonvulsant therapy.

NEW & NOTEWORTHY The anticonvulsant effect of dipropofol was shown in a mouse model of kainic acid-induced seizures. Whole cell patch-clamp recordings of brain slices showed suppression of cortical neuronal excitability by dipropofol. Dipropofol activated the native tonic GABAA currents in a dose-dependent manner.

Assessing low-frequency oscillations in cerebrovascular diseases and related conditions with near-infrared spectroscopy: a plausible method for evaluating cerebral autoregulation?

BACKGROUND

Cerebral autoregulation (CA) is the brain's ability to always maintain an adequate and relatively constant blood supply, which is often impaired in cerebrovascular diseases. Near-infrared spectroscopy (NIRS) examines oxygenated hemoglobin (OxyHb) in the cerebral cortex. Low- and very low-frequency oscillations ( LFOs ≈ 0.1    Hz and VLFOs ≈ 0.05 to 0.01 Hz) in OxyHb have been proposed to reflect CA.

AIM

To systematically review published results on OxyHb LFOs and VLFOs in cerebrovascular diseases and related conditions measured with NIRS.

APPROACH

A systematic search was performed in the MEDLINE database, which generated 36 studies relevant for inclusion.

RESULTS

Healthy people have relatively stable LFOs. LFO amplitude seems to reflect myogenic CA being decreased by vasomotor paralysis in stroke, by smooth muscle damage or as compensatory action in other conditions but can also be influenced by the sympathetic tone. VLFO amplitude is believed to reflect neurogenic and metabolic CA and is lower in stroke, atherosclerosis, and with aging. Both LFO and VLFO synchronizations appear disturbed in stroke, while the former is also altered in internal carotid stenosis and hypertension.

CONCLUSION

We conclude that amplitudes of LFOs and VLFOs are relatively robust measures for evaluating mechanisms of CA and synchronization analyses can show temporal disruption of CA. Further research and more coherent methodologies are needed.

Immunological, vascular, metabolic, and autonomic changes seen with aging possible implications for poor outcomes in the elderly following decompressive hemicraniectomy for malignant MCA stroke: a critical review

INTRODUCTION

Stroke is one of the leading causes of mortality and morbidity worldwide and requires rapid and intensive treatment to prevent adverse outcomes. Decompressive hemicraniectomy stands as the gold standard for surgical resolution of the intracranial swelling which accompanies cerebral infarction; however, the benefits of this procedure are not as well achieved in the elderly (age >65 years) compared to the younger population.

EVIDENCE ACQUISITION

This is a critical review performed on all available literature relating to middle cerebral artery (MCA) stroke in the elderly with emphasis on articles examining causality of adverse outcomes in this group over younger populations. Utilizing PRISMA guidelines, we initially identified 1462 articles.

EVIDENCE SYNTHESIS

After screening, four clear areas of physiological change associated with aging were identified and expounded upon as they relate to MCA stroke. These four areas include: immunological, autonomic, mitochondrial, and vascular changes. Elderly patients have a decreased and declining capacity to regulate the inflammation that develops postinfarction and this contributes to adverse outcomes from a neurological stand point. Additionally, aging decreases the ability of elderly patients to regulate their autonomic system resulting in aberrant blood pressures systemically post infarction. With age, the mitochondrial response to ischemia is exaggerated and causes greater local damage in elderly patients compared to younger populations. Finally, there are numerous vascular changes that occur with age including accumulation of homocysteine and atherosclerosis which together contributed to decreased structural integrity of the vasculature in the elderly and render decreased support to the recovery process post infarction.

CONCLUSIONS

We conclude that physiological changes inherent in the aging process serve to intensify adverse outcomes that are commonly associated with strokes in the elderly. Identification and subsequent minimization of these risk factors could allow for more effective management of elderly patients, post stroke, and promote better clinical outcomes.

Electroacupuncture brain protection during ischemic stroke: A role for the parasympathetic nervous system

The demand for using parasympathetic activation for stroke therapy is unmet. In the current study, we investigated whether the neuroprotection provided by electroacupuncture (EA) in an experimental stroke model was associated with activation of the parasympathetic nervous system (PNS). The results showed that parasympathetic dysfunction (PD), performed as unilateral vagotomy combined with peripheral atropine, attenuated both the functional benefits of EA and its effects in improving cerebral perfusion, reducing infarct volume, and hindering apoptosis, neuronal and peripheral inflammation, and oxidative stress. Most importantly, EA rats showed a dramatically less reduction in the mRNA level of choline acetyltransferase, five subtypes of muscarinic receptors and α7nAChR, suggesting the inhibition of the impairment of the central cholinergic system; EA also activated dorsal motor nucleus of the vagus, the largest source of parasympathetic pre-ganglionic neurons in the lower brainstem (detected by c-fos immunohistochemistry), and PD suppressed these changes. These findings indicated EA may serve as an alternative modality of PNS activation for stroke therapy.