Past, present, and future of endovascular stroke therapies

History of Neurointervention

In this review article, we aim to provide a summary of the discoveries and developments that were instrumental in the evolution of the Neurointerventional field. We begin with developments in the advent of Diagnostic Cerebral Angiography and progress to cerebral aneurysm treatment, embolization in AVMs and ischemic stroke treatment. In the process we discuss many persons who were key in the development and maturation of the field. A pivotal aspect to rapid growth in the field has been the multidisciplinary involvement of the different neuroscience specialties and therefore we close out our discussion with excitement about ongoing and future developments in the field with a focus on treatments in the non-cerebrovascular disease realm.

Robotic versus Conventional Overground Gait Training in Subacute Stroke Survivors: A Multicenter Controlled Clinical Trial

BACKGROUND

Although stroke survivors can benefit from robotic gait rehabilitation, stationary robot-assisted gait training needs further investigation. In this paper, we investigated the efficacy of this approach (with an exoskeleton or an end-effector robot) in comparison to the conventional overground gait training in subacute stroke survivors.

METHODS

In a multicenter controlled clinical trial, 89 subacute stroke survivors conducted twenty sessions of robot-assisted gait training (Robotic Group) or overground gait training (Control Group) in addition to the standard daily therapy. The robotic training was performed with an exoskeleton (RobotEXO-group) or an end-effector (RobotEND-group). Clinical outcomes were assessed before (T0) and after (T1) the treatment. The walking speed during the 10-Meter Walk Test (10 MWT) was the primary outcome of this study, and secondary outcomes were the 6-Minute Walk Test (6 MWT), Timed Up and Go test (TUG), and the modified Barthel Index (mBI).

RESULTS

The main characteristics assessed in the Robotic and Control groups did not differ at baseline. A significant benefit was detected from the 10 MWT in the Robotic Group at the end of the study period (primary endpoint). A benefit was also observed from the following parameters: 6 MWT, TUG, and mBI. Moreover, patients belonging to the Robot Group outperformed the Control Group in gait speed, endurance, balance, and ADL. The RobotEND-group improved their walking speed more than the RobotEXO-group.

CONCLUSION

The stationary robot-assisted training improved walking ability better than the conventional training in subacute stroke survivors. These results suggest that people with subacute stroke may benefit from Robot-Assisted training in potentiating gait speed and endurance. Our results also support that end-effector robots would be superior to exoskeleton robots for improving gait speed enhancement.

A Review on Preclinical Models of Ischemic Stroke: Insights Into the Pathomechanisms and New Treatment Strategies

BACKGROUND

Stroke is a serious neurovascular problem and the leading cause of disability and death worldwide. The disrupted demand to supply ratio of blood and glucose during cerebral ischemia develops hypoxic shock, and subsequently necrotic neuronal death in the affected regions. Multiple causal factors like age, sex, race, genetics, diet, and lifestyle play an important role in the occurrence as well as progression of post-stroke deleterious events. These biological and environmental factors may be contributed to vasculature variable architecture and abnormal neuronal activity. Since recombinant tissue plasminogen activator is the only clinically effective clot bursting drug, there is a huge unmet medical need for newer therapies for the treatment of stroke. Innumerous therapeutic interventions have shown promise in the experimental models of stroke but failed to translate it into clinical counterparts.

METHODS

Original publications regarding pathophysiology, preclinical experimental models, new targets and therapies targeting ischemic stroke have been reviewed since the 1970s.

RESULTS

We highlighted the critical underlying pathophysiological mechanisms of cerebral stroke and preclinical stroke models. We discuss the strengths and caveats of widely used ischemic stroke models, and commented on the potential translational problems. We also describe the new emerging treatment strategies, including stem cell therapy, neurotrophic factors and gut microbiome-based therapy for the management of post-stroke consequences.

CONCLUSION

There are still many inter-linked pathophysiological alterations with regards to stroke, animal models need not necessarily mimic the same conditions of stroke pathology and newer targets and therapies are the need of the hour in stroke research.

Combining Upper Limb Robotic Rehabilitation with Other Therapeutic Approaches after Stroke: Current Status, Rationale, and Challenges

A better understanding of the neural substrates that underlie motor recovery after stroke has led to the development of innovative rehabilitation strategies and tools that incorporate key elements of motor skill relearning, that is, intensive motor training involving goal-oriented repeated movements. Robotic devices for the upper limb are increasingly used in rehabilitation. Studies have demonstrated the effectiveness of these devices in reducing motor impairments, but less so for the improvement of upper limb function. Other studies have begun to investigate the benefits of combined approaches that target muscle function (functional electrical stimulation and botulinum toxin injections), modulate neural activity (noninvasive brain stimulation), and enhance motivation (virtual reality) in an attempt to potentialize the benefits of robot-mediated training. The aim of this paper is to overview the current status of such combined treatments and to analyze the rationale behind them.

Emergent loading dose of antiplatelets for stenting after IV rt-PA in acute ischemic stroke: a feasibility study

BACKGROUND

A loading dose of antiplatelets reduces in-stent thrombosis after stent implantation. However, whether it is safe in patients undergoing acute stenting after intravenous recombinant tissue plasminogen activator (rt-PA) is unclear.

METHODS

A case series of acute ischemic stroke patients treated with intravenous rt-PA followed by emergent stenting were prospectively included in Jinling Hospital Stroke Unit. An emergent loading dose of antiplatelets (aspirin 300 mg and clopidogrel 300 mg) were administered to all patients through a nasogastric tube immediately before stenting. Clinical and angiographic outcomes were evaluated in these patients.

RESULTS

A total of 12 patients were included. The median of NIHSS score on admission was 15 points (interquartile range 11-19). The median of time from stroke symptom onset to start IV rt-PA and stent placement was 172 min (interquartile range 123.75-189) and 311.5 min (interquartile range 285.5-349.5), respectively. All patients reached complete or partial recanalization (TICI ≥2a). One patient occurred hemorrhagic transformation at 24 h following the emergent loading dose of antiplatelets. A favorable outcome as defined by mRS ≤2 at 90 days was obtained in 58.3% (7/12) of all patients.

CONCLUSION

Our finding preliminary suggested that an emergent loading dose of antiplatelets may be safe and feasible for acute stenting after IV rt-PA.

Glucagon-like receptor 1 agonists and DPP-4 inhibitors: Anti-diabetic drugs with anti-stroke potential

Stroke is one of the leading causes of death and serious disability in Westernized societies. The risk of stroke approximately doubles with each decade after the age of 55. Therefore, even though the incidence of stroke is declining, mostly because of the efforts to lower blood pressure and reduce smoking, the overall number of strokes is increasing due to the aging of the population. While stroke prevention by healthy lifestyle is effective in decreasing the risk of stroke, post stroke pharmacological strategies aimed at minimizing stroke-induced brain damage and promoting recovery are highly needed. Unfortunately, several candidate drugs that have shown significant neuroprotective efficacy in experimental models have failed in clinical trials and no treatment for stroke based on pharmacological neuroprotection is available today. Glucagon-like peptide 1 receptor (GLP-1R) agonists and dipeptidyl peptidase-4 inhibitors (DPP-4i) are clinically used against type 2 diabetes. Interestingly, these drugs have also shown promising effects in decreasing stroke incidence and increasing neuroprotection in clinical and preclinical studies, respectively. However, the mode of action of these drugs in the brain is largely unknown. Moreover, while it was previously thought that GLP-1R agonists and DPP-4i act via similar mechanisms of action, recent data argue against this hypothesis. Herein, we review this promising research area and highlight the main questions in the field whose answers could reveal important aiming to developing effective anti-stroke therapies. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'

Experimental animal models and inflammatory cellular changes in cerebral ischemic and hemorrhagic stroke

Stroke, including cerebral ischemia, intracerebral hemorrhage, and subarachnoid hemorrhage, is the leading cause of long-term disability and death worldwide. Animal models have greatly contributed to our understanding of the risk factors and the pathophysiology of stroke, as well as the development of therapeutic strategies for its treatment. Further development and investigation of experimental models, however, are needed to elucidate the pathogenesis of stroke and to enhance and expand novel therapeutic targets. In this article, we provide an overview of the characteristics of commonly-used animal models of stroke and focus on the inflammatory responses to cerebral stroke, which may provide insights into a framework for developing effective therapies for stroke in humans.

Type of anesthesia and differences in clinical outcome after intra-arterial treatment for ischemic stroke

BACKGROUND AND PURPOSE

Intra-arterial treatment (IAT) in patients with acute ischemic stroke (AIS) can be performed with or without general anesthesia (GA). Previous studies suggested that IAT without the use of GA (non-GA) is associated with better clinical outcome. Nevertheless, no consensus exists about the anesthetic management during IAT of AIS patients. This study investigates the association between type of anesthesia and clinical outcome in a large cohort of patients with AIS treated with IAT.

METHODS

All consecutive patients with AIS of the anterior circulation who received IAT between 2002 and 2013 in 16 Dutch hospitals were included in the study. Primary outcome was functional outcome on the modified Rankin Scale at discharge. Difference in primary outcome between GA and non-GA was estimated using multiple ordinal regression analysis, adjusting for age, stroke severity, occlusion of the internal carotid artery terminus, previous stroke, atrial fibrillation, and diabetes mellitus.

RESULTS

Three hundred forty-eight patients were included in the analysis; 70 patients received GA and 278 patients did not receive GA. Non-GA was significantly associated with good clinical outcome (odds ratio 2.1, 95% confidence interval 1.02-4.31). After adjusting for prespecified prognostic factors, the point estimate remained similar; statistical significance, however, was lost (odds ratio 1.9, 95% confidence interval 0.89-4.24).

CONCLUSIONS

Our study suggests that patients with AIS of the anterior circulation undergoing IAT without GA have a higher probability of good clinical outcome compared with patients treated with general anesthesia.

GLP-1R activation for the treatment of stroke: updating and future perspectives

Stroke is the leading cause of adult disability in Westernized societies with increased incidence along ageing and it represents a major health and economical threat. Inactive lifestyle, smoking, hypertension, atherosclerosis, obesity and diabetes all dramatically increase the risk of stroke. While preventive strategies based on lifestyle changes and risk factor management can delay or decrease the likelihood of having a stroke, post stroke pharmacological strategies aimed at minimizing stroke-induced brain damage are highly needed. Unfortunately, several candidate drugs that have shown significant preclinical neuroprotective efficacy, have failed in clinical trials and no treatment for stroke based on neuroprotection is available today. Glucagon-like peptide 1 (GLP-1) is a peptide originating in the enteroendocrine L-cells of the intestine and secreted upon nutrient ingestion. The activation of the GLP-1R by GLP-1 enhances glucose-dependent insulin secretion, suppresses glucagon secretion and exerts multifarious extrapancreatic effects. Stable GLP-1 analogues and inhibitors of the proteolytic enzyme dipeptidyl peptidase 4 (DPP-4) (which counteract endogenous GLP-1 degradation) have been developed clinically for the treatment of type 2 diabetes. Besides their antidiabetic properties, experimental evidence has shown neurotrophic and neuroprotective effects of GLP-1R agonists and DPP-4 inhibitors in animal models of neurological disorders. Herein, we review recent experimental data on the neuroprotective effects mediated by GLP-1R activation in stroke. Due to the good safety profile of the drugs targeting the GLP-1R, we also discuss the high potential of GLP-1R stimulation in view of developing a safe clinical treatment against stroke based on neuroprotection in both diabetic and non-diabetic patients.

Efficient transduction of 11 poly-arginine peptide in an ischemic lesion of mouse brain

Direct intracellular delivery of intact proteins has been successfully achieved by tagging cell-penetrating peptide (CPP), which consists of short positively charged amino acids, such as 11 poly-arginine (11R); however, in vivo delivery of the proteins to the brain has remained challenging because it is unclear whether CPP would enable proteins to cross the blood-brain barrier (BBB). In this study, we conducted an in vivo kinetic study to investigate the efficiency of 11R-mediated peptide delivery in the normal and ischemic brain. The 11R was observed in the microvessels and neurons surrounding the microvessels throughout the brain 1 hour after systemic administration, but the signal of the peptide was faint after 2 hours. In a transient middle cerebral artery occlusion mouse model, 11R was markedly enhanced and remained detectable in the cells on the ipsilateral side for as long as 8 hours after administration compared with the contralateral side. These results suggest that 11R is capable of in vivo delivery to the brain by passing through the BBB. Furthermore, 11R-mediated protein transduction could be used for the delivery of therapeutic molecules in cerebral ischemia.

Successful recanalization with multimodality endovascular interventional therapy in acute ischemic stroke

Stroke is an important cause of death and disability in adults. However, effective treatments for patients with acute ischemic stroke are limited. Intravenous recombinant tissue plasminogen activator (iv rtPA) within 4.5 h after onset has been approved as a standard treatment for patients with acute ischemic stroke. However, due to time constraints, less than one percent of acute ischemic stroke patients in Thailand are able to obtain iv rtPA. Although endovascular interventional therapy has not yet been approved as standard treatment in acute ischemic stroke, it is the one of the potentially effective treatment options. There are several reliable methods of endovascular therapy for acute ischemic stroke patients. Endovascular interventional therapy has rarely been done in Thailand. We report seven patients with successful recanalization after endovascular treatment in acute large vessel stroke from a single stroke center in Thailand. Patient screening and selection with multimodal imaging protocol and multimodality methods of endovascular interventional therapy are described.

Efficacy and safety of therapies for acute ischemic stroke in China: a network meta-analysis of 13289 patients from 145 randomized controlled trials

BACKGROUND

Many of these therapies have been compared against placebos, but have not been directly compared against each other. To evaluate the efficacy and safety of several commonly used drugs for AIS directly or indirectly.

METHODS

A systematic literature review was performed to identify randomized controlled trials (RCTs) published prior to April 2013 for AIS therapies. The primary outcome measures were the National Institutes of Health Stroke Scale (NIHSS) scores and the clinical effective rate. A fixed-effects meta-analysis and meta-regression are performed; lastly, performed a mixed treatment comparison was performed through the Bayesian methods.

RESULTS

Outcome of efficacy of therapies for acute ischemic stroke are as followed: All of the therapies mentioned above yielded results a more effective result than placebo, Sodium ozagrel (RR 3.86, 95%CI 3.18-4.61); Sodium ozagrel + edaravone (RR 9.60, 95%CI 7.04-13.06); Edaravone (RR 4.07, 95%CI 3.30-5.01); Edaravone + Kininogenase (RR 15.33, 95%CI 10.03-23.05). The significant difference in efficacy between edaravone monotherapy and Sodium ozagrel + edaravone was evident (RR 0.43, 95%CI 0.08-0.61) and was also significant between efficacy of edaravone + Kininogenase and Sodium ozagrel (RR 4.00, 95%CI 2.47-6.24). The differences between the risk and benefit were not significant when comparing Sodium ozagrel and edaravone or edaravone + Kininogenase and Sodium ozagrel + Edaravone for AIS. Outcome of the defect of neurological function: Placebo served a significant difference in treating the defects of neurological function compared with Sodium ozagrel (WMD = -3.11, 95%CI -4.43 to -1.79), Sodium ozagrel + edaravone (WMD = -6.25, 95%CI -7.96 to -4.54) and Edaravone + Kininogenase (WMD =  -3.47, 95%CI -5.73 to -1.21).

CONCLUSIONS

It provides that the efficacy of edaravone monotherapy in treatment was not more effective than Sodium ozagrel + edaravone.The efficacy of edaravone + Kininogenase monotherapy in treatment was more effective than Sodium ozagrel. Edaravone + Kininogenase and Sodium ozagrel + Edaravone appeared the most effective treatments. And Sodium ozagrel, Sodium ozagrel + edaravone, Edaravone + Kininogenase can improve the nerve dysfunction.

Status of endovascular interventions to treat acute ischemic stroke

OPINION STATEMENT

Acute stroke is a major component of neurology and one of few neurologic emergencies. Despite many efforts to increase treatment of acute ischemic stroke, we are still not able to treat a significant percentage of patients with intravenous tPA, typically because of time restrictions. Unfortunately, many patients do not present to medical attention within the short window for tPA administration. In addition, there are numerous contraindications for tPA, which make more patients ineligible. Endovascular treatment for acute ischemic stroke may help to expand the number of patients treated by extending the time window beyond the 3 to 4.5 hour constraints of IV tPA, and including patients with tPA contraindications such as use of oral anticoagulants. However, several recent studies have raised questions regarding the utility and efficacy of these procedures. These studies should not discourage endovascular treatment of acute stroke, but should lead us to ask more questions and be proactive in seeking answers, and should make us carefully select the patient population to receive the treatment. Future studies should take advantage of the lessons learned from these recent trials, including the importance of using vascular imaging for inclusion criteria, and of utilizing the latest and most advanced devices and techniques. Endovascular therapy will continue to evolve into what will hopefully be a clinically significant alternative therapy for acute ischemic stroke.

Rehabilitation with poststroke motor recovery: a review with a focus on neural plasticity

Motor recovery after stroke is related to neural plasticity, which involves developing new neuronal interconnections, acquiring new functions, and compensating for impairment. However, neural plasticity is impaired in the stroke-affected hemisphere. Therefore, it is important that motor recovery therapies facilitate neural plasticity to compensate for functional loss. Stroke rehabilitation programs should include meaningful, repetitive, intensive, and task-specific movement training in an enriched environment to promote neural plasticity and motor recovery. Various novel stroke rehabilitation techniques for motor recovery have been developed based on basic science and clinical studies of neural plasticity. However, the effectiveness of rehabilitative interventions among patients with stroke varies widely because the mechanisms underlying motor recovery are heterogeneous. Neurophysiological and neuroimaging studies have been developed to evaluate the heterogeneity of mechanisms underlying motor recovery for effective rehabilitation interventions after stroke. Here, we review novel stroke rehabilitation techniques associated with neural plasticity and discuss individualized strategies to identify appropriate therapeutic goals, prevent maladaptive plasticity, and maximize functional gain in patients with stroke.