The role of sonolysis and sonothrombolysis in acute ischemic stroke: a systematic review and meta-analysis of randomized controlled trials and case-control studies

Exosomes and ultrasound: The future of theranostic applications

Biomaterials and pertaining formulations have been very successful in various diagnostic and therapeutic applications because of its ability to overcome pharmacological limitations. Some of them have gained significant focus in the recent decade for their theranostic properties. Exosomes can be grouped as biomaterials, since they consist of various biological micro/macromolecules and possess all the properties of a stable biomaterial with size in nano range. Significant research has gone into isolation and exploitation of exosomes as potential theranostic agent. However, the limitations in terms of yield, efficacy, and target specificity are continuously being addressed. On the other hand, several nano/microformulations are responsive to physical or chemical alterations and were successfully stimulated by tweaking the physical characteristics of the surrounding environment they are in. Some of them are termed as photodynamic, sonodynamic or thermodynamic therapeutic systems. In this regard, ultrasound and acoustic systems were extensively studied for its ability towards altering the properties of the systems to which they were applied on. In this review, we have detailed about the diagnostic and therapeutic applications of exosomes and ultrasound separately, consisting of their conventional applications, drawbacks, and developments for addressing the challenges. The information were categorized into various sections that provide complete overview of the isolation strategies and theranostic applications of exosomes in various diseases. Then the ultrasound-based disease diagnosis and therapy were elaborated, with special interest towards the use of ultrasound in enhancing the efficacy of nanomedicines and nanodrug delivery systems, Finally, we discussed about the ability of ultrasound in enhancing the diagnostic and therapeutic properties of exosomes, which could be the future of theranostics.

Overview of Imaging Modalities in Stroke

PURPOSE OF THE REVIEW

This article reviews common imaging modalities used in diagnosis and management of acute stroke. Each modality is discussed individually and clinical scenarios are presented to demonstrate how to apply these modalities in decision-making.

RECENT FINDINGS

Advances in neuroimaging provide unprecedented accuracy in determining tissue viability as well as tissue fate in acute stroke. In addition, advances in machine learning have led to the creation of decision support tools to improve the interpretability of these studies.

SUMMARY

Noncontrast head computed tomography (CT) remains the most commonly used initial imaging tool to evaluate stroke. Its exquisite sensitivity for hemorrhage, rapid acquisition, and widespread availability make it the ideal first study. CT angiography (CTA), the most common follow-up study after noncontrast head CT, is used primarily to identify intracranial large vessel occlusions and cervical carotid or vertebral artery disease. CTA is highly sensitive and can improve accuracy of patient selection for endovascular therapy through delineations of ischemic core. CT perfusion is widely used in endovascular therapy trials and benefits from multiple commercially available machine-learning packages that perform automated postprocessing and interpretation. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) can provide valuable insights for outcomes prognostication as well as stroke etiology. Optical coherence tomography (OCT), positron emission tomography (PET), single-photon emission computerized tomography (SPECT) offer similar insights. In the clinical scenarios presented, we demonstrate how multimodal imaging approaches can be tailored to gain mechanistic insights for a range of cerebrovascular pathologies.

Advances in Biological Application of and Research on Low-Frequency Ultrasound

In recent years, the in-depth study of low-frequency sonophoresis (LFS) has greatly elucidated its biological effects in various therapeutic applications, including drug delivery, enhanced healing, thrombolytic technology, anti-inflammatory effects and tumor treatment. Specifically, numerous studies have reported its use in drug delivery and synergistic antitumor activity, indicating a new treatment direction for cancer. However, there are significant gaps in the understanding of LFS in terms of frequency and sound intensity safety; these issues are becoming increasingly important in understanding the biological effects of LFS ultrasound. This article reviews the treatment mechanism and current applications of LFS technology and discusses and summarizes its safety and application prospects.

Accelerated sonothrombolysis with Definity in a xenographic porcine cerebral thromboembolism model

Adjuvant ultrasound at 2 MHz with or without an ultrasound contrast agent improves the rate of thrombus resolution by recombinant tissue plasminogen activator (rt-PA) in laboratory and clinical studies. A sub-megahertz approach can further expand this therapy to a subset of patients with an insufficient temporal bone window, improving efficacy in unselected patient populations. The aim of this study was to determine if a clinical ultrasound contrast agent (UCA), Definity, and 220 kHz pulsed ultrasound accelerated rt-PA thrombolysis in a preclinical animal model of vascular occlusion. The effect of Definity and ultrasound on thrombus clearance was first investigated in vitro and subsequently tested in a xenographic porcine cerebral thromboembolism model in vivo. Two different microcatheter designs (end-hole, multi-side-hole) were used to infuse rt-PA and Definity at the proximal edge or directly into clots, respectively. Sonothrombolysis with Definity increased clot mass loss relative to saline or rt-PA alone in vitro, only when rt-PA was administered directly into clots via a multi-side-hole microcatheter. Combined treatment with rt-PA, Definity, and ultrasound in vivo increased the rate of reperfusion up to 45 min faster than clots treated with rt-PA or saline. In this porcine cerebral thromboembolism model employing retracted human clots, 220 kHz ultrasound, in conjunction with Definity increased the probability of early successful reperfusion with rt-PA.

Targeted nano-delivery strategies for facilitating thrombolysis treatment in ischemic stroke

Ischemic stroke is one of the major causes of severe disability and death worldwide. It is mainly caused by a sudden reduction in cerebral blood flow due to obstruction of the supplying vessel by thrombi and subsequent initiation of a complex cascade of pathophysiological changes, which ultimately lead to brain ischemia and even irreversible infarction. Thus, timely and effective thrombolysis therapy remains a mainstay for acute ischemic stroke treatment. Tissue plasminogen activator (tPA), the only thrombolytic agent approved globally, provides substantial benefits by exerting a fibrinolysis effect, recovering the blood supply in occluded vessels and, thereby, salvaging the ischemic tissue. However, the clinical application of tPA was limited because of a few unsolved issues, such as a narrow therapeutic window, hemorrhagic complications, and limited thrombolytic efficacy, especially, for large thrombi. With the prosperous development of nanotechnology, a series of targeted delivery strategies and nanocomposites have been extensively investigated for delivering thrombolytic agents to facilitate thrombolysis treatment. Excitingly, numerous novel attempts have been reported to be effective in extending the half-life, targeting the thrombus site, and improving the thrombolytic efficacy in preclinical models. This article begins with a brief introduction to ischemic stroke, then describes the current state of thrombolysis treatment and, finally, introduces the application of various nanotechnology-based strategies for targeted delivery of thrombolytic agents. Representative studies are reviewed according to diverse strategies and nano-formulations, with the aim of providing integrated and up-to-date information and to improve the development of thrombolysis treatment for stroke patients.

Magnetic resonance-guided, high-intensity focused ultrasound sonolysis: potential applications for stroke

Stroke is one of the leading causes of death worldwide and a significant source of long-term morbidity. Unfortunately, a substantial number of stroke patients either are ineligible or do not significantly benefit from contemporary medical and interventional therapies. To address this void, investigators recently made technological advances to render transcranial MR-guided, high-intensity focused ultrasound (MRg-HIFU) sonolysis a potential therapeutic option for both acute ischemic stroke (AIS)-as an alternative for patients with emergent large-vessel occlusion (ELVO) who are ineligible for endovascular mechanical thrombectomy (EMT) or as salvage therapy for patients in whom EMT fails-and intracerebral hemorrhage (ICH)-as a neoadjuvant means of clot lysis prior to surgical evacuation. Herein, the authors review the technological principles behind MRg-HIFU sonolysis, its results in in vitro and in vivo stroke models, and its potential clinical applications. As a noninvasive transcranial technique that affords rapid clot lysis, MRg-HIFU thrombolysis may develop into a therapeutic option for patients with AIS or ICH. However, additional studies of transcranial MRg-HIFU are necessary to ascertain the merit of this treatment approach for thrombolysis in both AIS and ICH, as well as its technical limitations and risks.

In vitro examination of the thrombolytic efficacy of tenecteplase and therapeutic ultrasound compared to rt-PA

Background

Optimizing thrombolytic therapy is vital for improving stroke outcomes. We aimed to develop standardized thrombolysis conditions to evaluate the efficacy of tenecteplase (TNK) compared to the current gold standard rt-PA (alteplase), with and without additional ultrasound treatment. We also wanted to introduce a new analytical approach to quantify fibrin fiber density in transmission electron microscopy (TEM).

Methods

In vitro clots that are similar to ex vivo clots concerning their histological condition and their durability were generated from whole blood. For five treatment groups we compared relative clot weight loss (each n = 60) and fibrin fiber density in TEM (each n = 5). The control group (A) was treated only with plasma. Two groups were designated for each rt-PA (B + C) and TNK (D + E). Groups C and E were additionally treated with ultrasound. Dosages were 50 μg/ml for rt-PA and 30 μg/ml for TNK. Results were evaluated by using analyses of variance (ANOVA) and post-hoc t-tests.

Results

Weight loss was increased significantly for all groups compared to the control group. Both TNK groups showed significantly increased weight loss compared to their counterpart rt-PA group (p ≤ 0.001). For TEM only group D showed significantly decreased fibrin fiber density (p < 0.05) compared to both rt-PA groups. Ultrasound did not significantly increase dissolution of clots with either method (best p = 0.16).

Conclusions

Tenecteplase dissolved clots more effectively than rt-PA with and without ultrasound. A higher sample size could provide more convincing results for TEM.

Does the administration of sonothrombolysis along with tissue plasminogen activator improve outcomes in acute ischemic stroke? A systematic review and meta-analysis

This meta-analysis was conducted to assess the safety and efficacy of sonothrombolysis along with intravenous recombinant tissue plasminogen activator, alteplase (IV rtPA), in the management of acute ischemic stroke. Electronic databases were searched under different meSH terms without the restriction of time and language. 1415 studies were analyzed and seven studies that matched the inclusion criteria were selected. Multiple safety and efficacy outcomes were extracted. Our pooled analysis demonstrated that there is no significant difference between sonothrombolysis group and control group in preventing mortality (RR 1.10 [0.81, 1.50]; p = 0.55; I² = 0%) and intracranial hemorrhage (RR 1.11 [0.76, 1.63]; p = 0.59; i² = 0%), however, among the efficacy outcomes; complete recanalization after 60-120 min was achieved more effectively in the sonothrombolysis group (RR 2.11 [1.48, 3.03]; p ≤ 0.0001; I² = 0%). The rest of the efficacy outcomes like neurological improvement at 24 h (RR 1.20 [0.92, 1.57]; p = 0.18; I² = 40%) and excellent functional outcome after 3 months (RR 1.19 [0.93, 1.52]; p = 0.17; I² = 35%) showed no significant differences between the two groups. In subgroup analysis, we found that sonothrombolysis led to a better neurological improvement in patients who were less than 65 years of age (RR 1.20 [0.92, 1.57]; p = 0.05; I² = 40%). Moreover, there were no significant differences in the following of the subgroups assessed: (a) microsphere or microbubble use, (b) Ultrasound frequency (2 MHz or < 2 MHz), (c) transcranial Doppler (TCD) duration (1 h or 2 h), (d) age (≤ 65 or > 65).

Research progress in ultrasound use for the diagnosis and treatment of cerebrovascular diseases

Cerebrovascular diseases pose a serious threat to human survival and quality of life and represent a major cause of human death and disability. Recently, the incidence of cerebrovascular diseases has increased yearly. Rapid and accurate diagnosis and evaluation of cerebrovascular diseases are of great importance to reduce the incidence, morbidity and mortality of cerebrovascular diseases. With the rapid development of medical ultrasound, the clinical relationship between ultrasound imaging technology and the diagnosis and treatment of cerebrovascular diseases has become increasingly close. Ultrasound techniques such as transcranial acoustic angiography, doppler energy imaging, three-dimensional craniocerebral imaging and ultrasound thrombolysis are novel and valuable techniques in the study of cerebrovascular diseases. In this review, we introduce some of the new ultrasound techniques from both published studies and ongoing trials that have been confirmed to be convenient and effective methods. However, additional evidence from future studies will be required before some of these techniques can be widely applied or recommended as alternatives.

Efficacy and safety of sonothombolysis versus non-sonothombolysis in patients with acute ischemic stroke: A meta-analysis of randomized controlled trials

Recent studies have shown that inconsistent results of safety and efficacy between sonothombolysis vs. non-sonothombolysis in acute ischemic stroke (AIS). We implemented a meta-analysis to explore the value of sonothrombolysis in AIS treatment. The MEDLINE, EMBASE, and Cochrane Library databases were searched for randomized controlled trials (RCTs) which had evaluated sonothrombolysis or ultrasound thrombolysis in AIS. One hundred five studies were retrieved and analyzed, among them, 7 RCTs were included in the current meta-analysis. In comparison with the non-sonothombolysis, sonothrombolysis significantly improved complete recanalization (RR 2.16, 95% CI 1.51 to 3.08, P < 0.001), complete or partial recanalization (RR 1.90, 95% CI 1.26 to 2.88, P = 0.002), there is also a tendency to improvement of ≥ 4 points in NIHSS score (RR 1.43, 95% CI 0.99 to 2.07, P = 0.057). However, sonothrombolysis and non-sonothrombolysis had insignificant differences in neurological recovery and adverse events. In subgroup analysis, we found that “With t-PA”, “NIHSS > 15”, “Treatment time ≤ 150min”, and “Age ≤ 65 years” are potential favorable factors for efficacy outcomes of sonothombolysis. Sonothrombolysis can significantly increase the rate of recanalization in patients with AIS compared with non-sonothrombolysis, but there is no significant effect on improving neurological functional recovery and avoiding complications.

Challenges in the Treatment of Glioblastoma: Multisystem Mechanisms of Therapeutic Resistance

Glioblastoma is one of the most lethal human cancers, with poor survival despite surgery, radiation treatment, and chemotherapy. Advances in the treatment of this type of brain tumor are limited because of several resistance mechanisms. Such mechanisms involve limited drug entry into the central nervous system compartment by the blood-brain barrier and by actions of the normal brain to counteract tumor-targeting medications. In addition, the vast heterogeneity in glioblastoma contributes to significant therapeutic resistance by preventing adequate control of the entire tumor mass by a single drug and by facilitating escape mechanisms from targeted agents. The stem cell-like characteristics of glioblastoma promote resistance to chemotherapy, radiation, and immunotherapy through upregulation of efflux transporters, promotion of glioblastoma stem cell proliferation in neurogenic zones, and immune suppression, respectively. Metabolic cascades in glioblastoma prevent effective treatments through the optimization of glucose use, the use of alternative nutrient precursors for energy production, and the induction of hypoxia to enhance tumor growth. In the era of precision medicine, an assortment of molecular techniques is being developed to target an individual's unique tumor, with the hope that this personalized strategy will bypass therapeutic resistance. Although each resistance mechanism presents an array of challenges to effective treatment of glioblastoma, as the field recognizes and addresses these difficulties, future treatments may have more efficacy and promise for patients with glioblastoma.

Sonolysis in risk reduction of symptomatic and silent brain infarctions during coronary stenting (SONOREDUCE): Randomized, controlled trial

BACKGROUND

Silent brain infarcts can be detected on magnetic resonance imaging (MRI) in ~22% of patients after coronary angioplasty and stenting (CS). The effect of periprocedural sonolysis on the risk of new brain infarcts during CS was examined.

METHODS

Patients undergoing elective CS were allocated randomly to a bilateral sonolysis group (70 patients, 58 men; mean age, 59.9 years) or a control group (74 patients, 45 men; mean age, 65.5 years). Neurologic examination, cognitive function tests, and brain MRI were performed prior to intervention and at 24 h after CS. Neurologic examination and cognitive function tests were repeated at 30 days after CS.

RESULTS

No significant differences were observed in the number of patients with new infarcts (25.7 vs. 18.9%, P = 0.423), the number of lesions (1.3 ± 1.0 vs. 2.9 ± 5.3, P = 0.493), lesion volume (0.16 ± 0.34 vs. 0.28 ± 0.60 mL, P = 0.143), and the number of patients with new ischemic lesions in the insonated MCA territories (18.6vs. 17.6%, P = 0.958) between the sonolysis group and the control group. There were no cases of stroke, transient ischemic attack, myocardial infarction, or death in the two groups. Intracranial bleeding was reported only in 1 patient in the control group (0 vs. 1.4%, P = 0.888). Clock-drawing test scores at 30 days were significantly higher in the sonolysis group than in the control group (median 3.0 vs. 2.5, P = 0.031).

CONCLUSIONS

Sonolysis does not reduce the risk of new brain infarcts after CS. The effect of sonolysis on number and volume of ischemic lesions and cognitive function should be assessed in further studies.

ABCDE of prehospital ultrasonography: a narrative review

Prehospital point-of-care ultrasound used by nonradiologists in emergency medicine is gaining ground. It is feasible on-scene and during aeromedical transport and allows health-care professionals to detect or rule out potential harmful conditions. Consequently, it impacts decision-making in prioritizing care, selecting the best treatment, and the most suitable transport mode and destination. This increasing relevance of prehospital ultrasonography is due to advancements in ultrasound devices and related technology, and to a growing number of applications. This narrative review aims to present an overview of prehospital ultrasonography literature. The focus is on civilian emergency (trauma and non-trauma) setting. Current and potential future applications are discussed, structured according to the airway, breathing, circulation, disability, and environment/exposure (ABCDE) approach. Aside from diagnostic implementation and specific protocols, procedural guidance, therapeutic ultrasound, and challenges are reviewed.

Microbubbles combined with ultrasound therapy in ischemic stroke: A systematic review of in-vivo preclinical studies

BACKGROUND

Microbubbles (MBs) combined with ultrasound sonothrombolysis (STL) appears to be an alternative therapeutic strategy for acute ischemic stroke (IS), but clinical results remain controversial.

OBJECTIVE

The aim of this systematic review is to identify the parameters tested; to assess evidence on the safety and efficacy on preclinical data on STL; and to assess the validity and publication bias.

METHODS

Pubmed® and Web of ScienceTM databases were systematically searched from January 1995 to April 2017 in French and English. We included studies evaluating STL on animal stroke model. This systematic review was conducted in accordance with the PRISMA guidelines. Data were extracted following a pre-defined schedule by two of the authors. The CAMARADES criteria were used for quality assessment. A narrative synthesis was conducted.

RESULTS

Sixteen studies met the inclusion criteria. The result showed that ultrasound parameters and types of MBs were heterogeneous among studies. Numerous positive outcomes on efficacy were found, but only four studies demonstrated superiority of STL versus recombinant tissue-type plasminogen activator on clinical criteria. Data available on safety are limited.

LIMITATIONS

Quality assessment of the studies reviewed revealed a number of biases.

CONCLUSION

Further in vivo studies are needed to demonstrate a better efficacy and safety of STL compared to currently approved therapeutic options.

SYSTEMATIC REVIEW REGISTRATION

http://syrf.org.uk/protocols/.

Contrast-enhanced sonothrombolysis in acute ischemic stroke patients without intracranial large-vessel occlusion

BACKGROUND

Contrast-enhanced sonothrombolysis (CEST) leads to a more rapid recanalization in acute ischemic stroke caused by intracranial large-vessel occlusion (LVO). Animal studies have shown that CEST also may be safe and efficient in treating the ischemic microcirculation in the absence of LVO. The exact mechanism behind this treatment effect is not known. We aimed to assess safety and efficacy of CEST in acute ischemic stroke patients included in the Norwegian Sonothrombolysis in Acute Stroke Study (NOR-SASS) without LVO on admission CT angiography (CTA).

METHODS

NOR-SASS was a randomized controlled trial of CEST in ischemic stroke patients treated with intravenous thrombolysis within 4.5 hours after stroke onset. Patients were randomized to either CEST or sham CEST. In this study, patients were excluded if they had partial or total occlusion on admission CTA, ultrasound-resistant bone window, had received CEST with incorrect insonation as compared to stroke location on Magnetic resonance imaging (MRI), or were stroke mimics.

RESULTS

Of the 183 patients included in NOR-SASS, a total of 83 (45.4%) patients matched the inclusion criteria, of which 40 received CEST and 43 sham CEST. There were no patients with symptomatic intracranial hemorrhage (sICH) in the CEST group. Rates of asymptomatic ICH, microbleeds, and mortality were not increased in the CEST group. Neurological improvement at 24 hours and functional outcome at 90 days were similar in both groups.

CONCLUSION

CEST is safe in ischemic stroke patients without intracranial LVO. There were no differences in clinical outcomes between the treatment groups.

Improved thrombolytic effect with focused ultrasound and neuroprotective agent against acute carotid artery thrombosis in rat

Combination therapy with focused ultrasound (FUS) and a neuroprotective agent, BNG-1, was examined in an acute carotid thrombotic occlusion model using LED irradiation in rat to improve the thrombolytic effect of rt-PA. Seven treatment groups included (A) intravenous bolus injection of 0.45 mg/kg rt-PA, (B) intravenous bolus injection of 0.9 mg/kg, (C) sonothrombolysis with FUS alone, (D) oral administration of 2 g/kg BNG-1 for 7 days alone, (E) A + D, (F) A + C, and (G) A + C + D. Four comparison groups were made including (H) 0.45 mg/kg rt-PA 20% bolus +80% IV fusion + FUS, (I) 0.9 mg/kg rt-PA with 10% bolus + 90% intravenous fusion, (J) B + C, (K) B + D. At 7 days after carotid occlusion, small-animal carotid ultrasound and 7 T MR angiography showed the recanalization rate of ≤50% stenosis was 50% in group B and 83% in group I, but 0% in groups A and C and 17% in group D. Combination therapy improved recanalization rate to 50–63% in groups E and F, to 67–83% in groups J and K, and to 100% in groups G and H. Our study demonstrated combination therapy with different remedies can be a feasible strategy to improve the thrombolytic effect of rt-PA.

Co-administration of tissue plasminogen activator and hyperbaric oxygen in ischemic stroke: a continued promise for neuroprotection

Intravenous recombinant tissue-type plasminogen activator (r-tPA, alteplase) remains the recommended therapy for acute ischemic stroke. However, several factors are limiting its practical use. It makes it urgent for us to search more efficient strategies that can save the ischemic neurons, and safely extend the time window, while in the mean time reducing the detrimental effects for stroke thrombolysis. Hyperbaric oxygen therapy (HBOT) is considered to be potentially neuroprotective. Co-administration of r-tPA and HBOT has already been proved to be effective, safe and feasible in myocardial infarction. In this article, we would like to review whether HBOT has any beneficial effects on r-tPA thrombolysis. If there is, what is the underlying possible mechanisms and how to optimize for maximal effects?

Effect of Qi-cultivating and mood-soothing bodybuilding exercise on psychological mood and degree of satisfaction with care in stroke patients with gastrointestinal bleeding

AIM

To observe the effect of Qi-cultivating and mood-soothing bodybuilding exercise on psychological mood and degree of satisfaction with care in stroke patients with gastrointestinal bleeding.

METHODS

Sixty stroke patients with gastrointestinal bleeding hospitalized at Yiwu Central Hospital of Zhejiang Province from April 2014 to October 2014 were randomly divided into either a control group or an observation group, with 32 cases in each group. Both groups were given conventional nursing, and the observation group additionally did Qi-cultivating and mood-soothing bodybuilding exercise. Anxiety, depression, patient satisfaction with care, and rebleeding were compared between the two groups.

RESULTS

Compared with the values before intervention, the Self-rating Anxiety Scale (SAS) and Self-rating Depression Scale (SDS) scores were significantly lower in both groups (P < 0.05), and the decrease in SAS and SDS scores was more significant in the observation group than in the control group (P < 0.05). After intervention, the scores of service attitude and initiative, care and communication, and health education as well as total score were significantly higher (P < 0.05) and the rate of rebleeding was significantly lower in the observation group than in the control group (P < 0.05).

CONCLUSION

Qi-cultivating and mood-soothing bodybuilding exercise can reduce anxiety and depression, improve the quality of life, and reduce rebleeding in stroke patients with gastrointestinal bleeding.

Treatment of Acute Ischemic Stroke

Although stroke declined from the third to fifth most common cause of death in the United States, the annual incidence and overall prevalence continue to increase. Since the available US Food and Drug Administration-approved treatment options are time dependent, improving early stroke care may have more of a public health impact than any other phase of care. Timely and efficient stroke treatment should be a priority for emergency department and prehospital providers. This article discusses currently available and emerging treatment options in acute ischemic stroke focusing on the preservation of salvageable brain tissue, minimizing complications, and secondary prevention.

SONOlysis in prevention of Brain InfaRctions During Internal carotid Endarterectomy (SONOBIRDIE) trial - study protocol for a randomized controlled trial

BACKGROUND

Carotid endarterectomy (CEA) is a beneficial procedure for selected patients with an internal carotid artery (ICA) stenosis. Surgical risk of CEA varies from between 2 and 15%. The aim of the study is to demonstrate the safety and effectiveness of sonolysis (continual transcranial Doppler monitoring, TCD) using a 2-MHz diagnostic probe with maximal diagnostic energy on the reduction of the incidence of stroke, transient ischemic attack (TIA) and brain infarction detected using magnetic resonance imaging (MRI) by the activation of the endogenous fibrinolytic system during CEA.

METHODS/DESIGN

Design: a multicenter, randomized, double-blind, sham-controlled trial.

SCOPE

international, multicenter trial for patients with at least 70% symptomatic or asymptomatic ICA stenosis undergoing CEA.

INCLUSION CRITERIA

patients with symptomatic or asymptomatic ICA stenosis of at least 70% are candidates for CEA; a sufficient temporal bone window for TCD; aged 40-85 years, functionally independent; provision of signed informed consent. Randomization: consecutive patients will be assigned to the sonolysis or control (sham procedure) group by computer-generated 1:1 randomization. Prestudy calculations showed that a minimum of 704 patients in each group is needed to reach a significant difference with an alpha value of 0.05 (two-tailed) and a beta value of 0.8 assuming that 10% would be lost to follow-up or refuse to participate in the study (estimated 39 endpoints).

ENDPOINTS

the primary endpoint is the incidence of stroke or TIA during 30 days after CEA and the incidence of new ischemic lesions on brain MRI performed 24 h after CEA in the sonolysis and control groups. Secondary endpoints are occurrence of death, any stroke, or myocardial infarction within 30 days, changes in cognitive functions 1 year post procedure related to pretreatment scores, and number of new lesions and occurrence of new lesions ≥0.5 mL on post-procedural brain MRI.

ANALYSIS

descriptive statistics and linear/logistic multiple regression models will be performed. Clinical relevance will be measured as relative risk reduction, absolute risk reduction and the number needed to treat.

DISCUSSION

Reduction of the periprocedural complications of CEA using sonolysis as a widely available and cheap method may significantly increase the safety of CEA and extend the indication criteria for CEA.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02398734 . Registered on 20 March 2015.

NOR-SASS (Norwegian Sonothrombolysis in Acute Stroke Study): Randomized Controlled Contrast-Enhanced Sonothrombolysis in an Unselected Acute Ischemic Stroke Population

Background and Purpose—

The NOR-SASS (Norwegian Sonothrombolysis in Acute Stroke Study) aimed to assess effect and safety of contrast-enhanced ultrasound treatment in an unselected acute ischemic stroke population.

Methods—

Patients treated with intravenous thrombolysis within 4.5 hours after symptom onset were randomized 1:1 to either contrast-enhanced sonothrombolysis (CEST) or sham CEST. A visible arterial occlusion on baseline computed tomography angiography was not a prerequisite for inclusion. Pulse-wave 2 MHz ultrasound was given for 1 hour and contrast (SonoVue) as an infusion for ≈30 minutes. Magnetic resonance imaging and angiography were performed after 24 to 36 hours. Primary study end points were neurological improvement at 24 hours defined as National Institutes of Health Stroke Scale score 0 or reduction of ≥4 National Institutes of Health Stroke Scale points compared with baseline National Institutes of Health Stroke Scale and favorable functional outcome at 90 days defined as modified Rankin scale score 0 to 1.

Results—

A total of 183 patients were randomly assigned to either CEST (93 patient) or sham CEST (90 patients). The rates of symptomatic intracerebral hemorrhage, asymptomatic intracerebral hemorrhage, or mortality were not increased in the CEST group. Neurological improvement at 24 hours and functional outcome at 90 days was similar in the 2 groups both in the intention-to-treat analysis and in the per-protocol analysis.

Conclusions—

CEST is safe among unselected ischemic stroke patients with or without a visible occlusion on computed tomography angiography and with varying grades of clinical severity. There was, however, statistically no significant clinical effect of sonothrombolysis in this prematurely stopped trial.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01949961.

Update on the effects of treatment with recombinant tissue-type plasminogen activator (rt-PA) in acute ischemic stroke

INTRODUCTION

Acute ischemic stroke (AIS) represents a major cause of death and disability all over the world. The recommended therapy aims at dissolving the clot to re-establish quickly the blood flow to the brain and reduce neuronal injury. Intravenous administration of recombinant tissue-type plasminogen activator (rt-PA) is clinically used with this goal.

AREAS COVERED

A description of beneficial and detrimental effects of rt-PA treatment is addressed. An overview of new therapies against AIS, such as new thrombolytics, sonolysis and sonothrombolysis, endovascular procedures, and association therapies is provided. Updates on the pathophysiological process leading to intracranial hemorrhage (ICH) is also discussed.

EXPERT OPINION

rt-PA treatment in AIS patients is beneficial to recovery outcomes. To weaken risks and improve benefits, it might be relevant to consider: i) a definitive identification of risk factors for symptomatic ICH; ii). a better organization of the health care system to reduce time-to-treatment and enhance discharge management. The pharmacological improvement of new thrombolytic drugs (such as tenecteplase and desmoteplase) targeting harmful and maximally exploiting beneficial effects might further reduce mortality and disability in AIS.

Sonolysis in Prevention of Brain Infarction During Cardiac Surgery (SONORESCUE): Randomized, Controlled Trial

Here, we examined whether intraoperative sonolysis can alter the risk of new ischemic lesions in the insonated brain artery territory during coronary artery bypass grafting (CABG) or valve surgery.Silent brain ischemic lesions could be detected in as many as two-thirds of patients after CABG or valve surgery.Patients indicated for CABG or valve surgery were allocated randomly to sonolysis (60 patients, 37 males; mean age, 65.3 years) of the right middle cerebral artery (MCA) during cardiac surgery and control group (60 patients, 37 males; mean age, 65.3 years). Neurologic examination, cognitive function tests, and brain magnetic resonance imaging (MRI) were conducted before intervention as well as 24 to 72 hours and 30 days after surgery.New ischemic lesions on control diffusion-weighted MRI in the insonated MCA territory ≥0.5 mL were significantly less frequent in the sonolysis group than in the control group (13.3% vs 26.7%, P = 0.109). The sonolysis group exhibited significantly reduced median volume of new brain ischemic lesions (P = 0.026). Stenosis of the internal carotid artery ≥50% and smoking were independent predictors of new brain ischemic lesions ≥0.5 mL (odds ratio = 5.685 [1.272-25.409], P = 0.023 and 4.698 [1.092-20.208], P = 0.038, respectively). Stroke or transient ischemic attack occurred only in 2 control patients (P = 0.496). No significant differences were found in scores for postintervention cognitive tests (P > 0.05).This study provides class-II evidence that sonolysis during CABG or valve surgery reduces the risk of larger, new ischemic lesions in the brain.www.clinicaltrials.gov (NCT01591018).

Sonothrombolysis with BR38 Microbubbles Improves Microvascular Patency in a Rat Model of Stroke

Background

Early recanalization of large cerebral vessels in ischemic stroke is associated with improved clinical outcome, however persisting hypoperfusion leads to poor clinical recovery despite large vessel recanalization. Limited experimental sonothrombolysis studies have shown that addition of microbubbles during treatment can improve microvascular patency. We aimed to determine the effect of two different microbubble formulations on microvascular patency in a rat stroke model.

Methods

We tested BR38 and SonoVue® microbubble-enhanced sonothrombolysis in Wistar rats submitted to 90-minute filament occlusion of the middle cerebral artery. Rats were randomized to treatment (n = 6/group): control, rt-PA, or rt-PA+3-MHz ultrasound insonation with BR38 or SonoVue® at full or 1/3 dose. Treatment duration was 60 minutes, beginning after withdrawal of the filament, and sacrifice was immediately after treatment. Vascular volumes were evaluated with microcomputed tomography.

Results

Total vascular volume of the ipsilateral hemisphere was reduced in control and rt-PA groups (p<0.05), but was not significantly different from the contralateral hemisphere in all microbubble-treated groups (p>0.1).

Conclusions

Microbubble-enhanced sonothrombolysis improves microvascular patency. This effect is not dose- or microbubble formulation-dependent suggesting a class effect of microbubbles promoting microvascular reopening. This study demonstrates that microbubble-enhanced sonothrombolysis may be a therapeutic strategy for patients with persistent hypoperfusion of the ischemic territory.

Ultrasound treatment of neurological diseases--current and emerging applications

Like cardiovascular disease and cancer, neurological disorders present an increasing challenge for an ageing population. Whereas nonpharmacological procedures are routine for eliminating cancer tissue or opening a blocked artery, the focus in neurological disease remains on pharmacological interventions. Setbacks in clinical trials and the obstacle of access to the brain for drug delivery and surgery have highlighted the potential for therapeutic use of ultrasound in neurological diseases, and the technology has proved useful for inducing focused lesions, clearing protein aggregates, facilitating drug uptake, and modulating neuronal function. In this Review, we discuss milestones in the development of therapeutic ultrasound, from the first steps in the 1950s to recent improvements in technology. We provide an overview of the principles of diagnostic and therapeutic ultrasound, for surgery and transient opening of the blood-brain barrier, and its application in clinical trials of stroke, Parkinson disease and chronic pain. We discuss the promising outcomes of safety and feasibility studies in preclinical models, including rodents, pigs and macaques, and efficacy studies in models of Alzheimer disease. We also consider the challenges faced on the road to clinical translation.

Sonothrombolysis

Thrombo-occlusive disease is a leading cause of morbidity and mortality. In this chapter, the use of ultrasound to accelerate clot breakdown alone or in combination with thrombolytic drugs will be reported. Primary thrombus formation during cardiovascular disease and standard treatment methods will be discussed. Mechanisms for ultrasound enhancement of thrombolysis, including thermal heating, radiation force, and cavitation, will be reviewed. Finally, in-vitro, in-vivo and clinical evidence of enhanced thrombolytic efficacy with ultrasound will be presented and discussed.

A pragmatic approach to sonothrombolysis in acute ischaemic stroke: the Norwegian randomised controlled sonothrombolysis in acute stroke study (NOR-SASS)

BACKGROUND

Ultrasound accelerates thrombolysis with tPA (sonothrombolysis). Ultrasound in the absence of tPA also accelerates clot break-up (sonolysis). Adding intravenous gaseous microbubbles may potentiate the effect of ultrasound in both sonothrombolysis and sonolysis. The Norwegian Sonothrombolysis in Acute Stroke Study aims in a pragmatic approach to assess the effect and safety of contrast enhanced ultrasound treatment in unselected acute ischaemic stroke patients.

METHODS/DESIGN

Acute ischaemic stroke patients ≥ 18 years, with or without visible arterial occlusion on computed tomography angiography (CTA) and treatable ≤ 4(½) hours after symptom onset, are included in NOR-SASS. NOR-SASS is superimposed on a separate trial randomising patients with acute ischemic stroke to either tenecteplase or alteplase (The Norwegian Tenecteplase Stroke Trial NOR-TEST). The NOR-SASS trial has two arms: 1) the thrombolysis-arms (NOR-SASS A and B) includes patients given intravenous thrombolysis (tenecteplase or alteplase), and 2) the no-thrombolysis-arm (NOR-SASS C) includes patients with contraindications to thrombolysis. First step randomisation of NOR-SASS A is embedded in NOR-TEST as a 1:1 randomisation to either tenecteplase or alteplase. Second step NOR-SASS randomisation is 1:1 to either contrast enhanced sonothrombolysis (CEST) or sham CEST. Randomisation in NOR-SASS B (routine alteplase group) is 1:1 to either CEST or sham CEST. Randomisation of NOR-SASS C is 1:1 to either contrast enhanced sonolysis (CES) or sham CES. Ultrasound is given for one hour using a 2-MHz pulsed-wave diagnostic ultrasound probe. Microbubble contrast (SonoVue®) is given as a continuous infusion for ~30 min. Recanalisation is assessed at 60 min after start of CEST/CES. Magnetic resonance imaging and angiography is performed after 24 h of stroke onset. Primary study endpoints are 1) major neurological improvement measured with NIHSS score at 24 h and 2) favourable functional outcome defined as mRS 0-1 at 90 days.

DISCUSSION

NOR-SASS is the first randomised controlled trial designed to test the superiority of contrast enhanced ultrasound treatment given ≤ 4(½) hours after stroke onset in an unselected acute ischaemic stroke population eligible or not eligible for intravenous thrombolysis, with or without a defined arterial occlusion on CTA. If a positive effect and safety can be proven, contrast enhanced ultrasound treatment will be an option for all acute ischaemic stroke patients. EudraCT No 201200032341; www.clinicaltrials.gov NCT01949961.

Outcomes following sonothrombolysis in severe acute ischemic stroke: subgroup analysis of the CLOTBUST trial

BACKGROUND

Sonothrombolysis is safe and may increase the likelihood of early recanalization in acute ischemic stroke patients.

AIMS

In preparation of a phase III clinical trial, we contrast the likelihood of achieving a sustained recanalization and functional independence in a post hoc subgroup analysis of patients randomized to transcranial Doppler monitoring plus intravenous tissue plasminogen activator (sonothrombolysis) compared with intravenous tissue plasminogen activator alone in the CLOTBUST trial.

METHODS

We analyzed the data from all randomized acute ischemic stroke patients with pretreatment National Institutes of Health Stroke Scale scores ≥ 10 points and proximal intracranial occlusions in the CLOTBUST trial. We compared sustained complete recanalization rate (Thrombolysis in Brain Ischemia flow grades 4-5) and functional independence (modified Rankin Scale 0-1) at 90 days. Safety was evaluated by the rate of symptomatic intracranial hemorrhage within 72 h of stroke onset.

RESULTS

Of 126 patients, a total of 85 acute ischemic stroke patients met our inclusion criteria: mean age 71 ± 11years, 56% men, median National Institutes of Health Stroke Scale 17 (interquartile range 14-20). Of these patients, 41 (48%) and 44 (52%) were randomized to intravenous tissue plasminogen activator alone and sonothrombolysis, respectively. More patients achieved sustained complete recanalization in the sonothrombolysis than in the intravenous tissue plasminogen activator alone group (38·6% vs. 17·1%; P = 0·032). Functional independence at 90 days was more frequently achieved in the sonothrombolysis than in the intravenous tissue plasminogen activator alone group (37·2% vs. 15·8%; P = 0·045). Symptomatic intracranial hemorrhage rate was similar in both groups (4·9% vs. 4·6%; P = 1·00).

CONCLUSIONS

Our results point to a signal of efficacy and provide information to guide the subsequent phase III randomized trial of sonothrombolysis in patients with severe ischemic strokes.

Reperfusion therapies of acute ischemic stroke: potentials and failures

Over the past 20 years, clinical research has focused on the development of reperfusion therapies for acute ischemic stroke (AIS), which include the use of systemic intravenous thrombolytics (alteplase, desmoteplase, or tenecteplase), the augmentation of systemic intravenous recanalization with ultrasound, the bridging of intravenous with intra-arterial thrombolysis, the use of multi-modal approaches to reperfusion including thrombectomy and thromboaspiration with different available retrievers. Clinical trials testing these acute reperfusion therapies provided novel insight regarding the comparative safety and efficacy, but also raised new questions and further uncertainty on the field. Intravenous alteplase (tPA) remains the fastest and easiest way to initiate acute stroke reperfusion treatment, and should continue to be the first-line treatment for patients with AIS within 4.5 h from onset. The use of tenecteplase instead of tPA and the augmentation of systemic thrombolysis with ultrasound are both novel therapeutical modalities that may emerge as significant options in AIS treatment. Endovascular treatments for AIS are rapidly evolving due to technological advances in catheter-based interventions and are currently emphasizing speed in order to result in timely restoration of perfusion of still-salvageable, infarcted brain tissue, since delayed recanalization of proximal intracranial occlusions has not been associated with improved clinical outcomes. Comprehensive imaging protocols in AIS may enable better patient selection for endovascular interventions and for testing multi-modal combinatory strategies.

Intravenous thrombolysis in acute ischemic stroke: standard and potential future applications

Acute ischemic stroke is a medical emergency requiring urgent treatment. Randomized clinical trial and Phase IV data have provided unequivocal evidence that intravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) improves early functional outcomes by restoring brain perfusion. Moreover, these studies have shed substantial light on the factors which are associated with more favorable outcome with tPA and are related to the highest benefit-to-risk ratio. Stroke physicians should consider vascular imaging techniques to aid decision making with thrombolytic therapy. The presence of intracranial occlusion is the target of treatment with early recanalization being the goal. Successful use of intravenous thrombolysis depends on a sound understanding of the decision-making process and organization of the treating team who strives for early treatment initiation and strict adherence to the protocol. Intravenous rt-PA within 4.5 h of onset should now be a standard treatment of acute disabling ischemic stroke throughout the world. This review also summarizes intravenous thrombolysis contraindications as well as the safety of novel reperfusion therapies including tenecteplase, sonothrombolysis and the combination of alteplase with direct thrombin inhibitors or glycoprotein IIb/IIIa receptor antagonists.

Update on intravenous recombinant tissue plasminogen activator for acute ischemic stroke

The controversial field of interventional stroke neurology has attracted considerable interest within the stroke community, but no endovascular interventional therapies have proved to be superior to intravenous (IV) recombinant tissue plasminogen activator (rtPA), the standard of care for patients with acute ischemic stroke. In this article, we review the evidence and background of IV thrombolysis for stroke, the clinical application of IV rtPA in practice, and the management of potential complications after thrombolysis. We conducted this review using a search of PubMed for articles published from January 1, 1995, to October 31, 2013, with the following terms: ischemic stroke, tissue plasminogen activator, TPA, alteplase, thrombolysis, and intracranial hemorrhage. Articles were also identified through searches of reference lists and the authors' files. In nearly 2 decades since the publication of the transformative National Institute of Neurological Disorders and Stroke trials, the efficacy and safety of IV rtPA has been consistently verified in international real-world clinical practice. Time from stroke symptom onset to thrombolysis is crucial and probably the most important determinant of success of IV therapy. Thus, optimal care of patients with acute stroke should include community education and standardized protocols to guide immediate patient assessment and triage to medical centers with capability for efficient neurologic assessment, brain imaging, drug administration, and specialized postthrombolysis care.

Comparative efficacy of different acute reperfusion therapies for acute ischemic stroke: a comprehensive benefit-risk analysis of clinical trials

BACKGROUND

Numerous acute reperfusion therapies (RPT) are currently investigated as potential new therapeutic targets in acute ischemic stroke (AIS). We conducted a comprehensive benefit-risk analysis of available clinical studies assessing different acute RPT, and investigated the utility of each intervention in comparison to standard intravenous thrombolysis (IVT) and in relation to the onset-to-treatment time (OTT).

METHODS

A comprehensive literature search was conducted to identify all available published, peer-reviewed clinical studies that evaluated the efficacy of different RPT in AIS. Benefit-to-risk ratio (BRR), adjusted for baseline stroke severity, was estimated as the percentage of patients achieving favorable functional outcome (BRR1, mRS score: 0-1) or functional independence (BRR2, mRS score: 0-2) at 3 months divided by the percentage of patients who died during the same period.

RESULTS

A total of 18 randomized (n = 13) and nonrandomized (n = 5) clinical studies fulfilled our inclusion criteria. IV therapy with tenecteplase (TNK) was found to have the highest BRRs (BRR1 = 5.76 and BRR2 = 6.82 for low-dose TNK; BRR1 = 5.80 and BRR2 = 6.87 for high-dose TNK), followed by sonothrombolysis (BRR1 = 2.75 and BRR2 = 3.38), while endovascular thrombectomy with MERCI retriever was found to have the lowest BRRs (BRR1 range, 0.31-0.65; BRR2 range, 0.52-1.18). A second degree negative polynomial correlation was detected between favorable functional outcome and OTT (R (2) value: 0.6419; P < 0.00001) indicating the time dependency of clinical efficacy of all reperfusion therapies.

CONCLUSION

Intravenous thrombolysis (IVT) with TNK and sonothrombolysis have the higher BRR among investigational reperfusion therapies. The combination of sonothrombolysis with IV administration of TNK appears a potentially promising therapeutic option deserving further investigation.