Stroke in the Time of Circadian Medicine.

Time-of-day significantly influences the severity and incidence of stroke. Evidence has emerged not only for circadian governance over stroke risk factors, but also for important determinants of clinical outcome. In this review, we provide a comprehensive overview of the interplay between chronobiology and cerebrovascular disease. We discuss circadian regulation of pathophysiological mechanisms underlying stroke onset or tolerance as well as in vascular dementia. This includes cell death mechanisms, metabolism, mitochondrial function, and inflammation/immunity. Furthermore, we present clinical evidence supporting the link between disrupted circadian rhythms and increased susceptibility to stroke and dementia. We propose that circadian regulation of biochemical and physiological pathways in the brain increase susceptibility to damage after stroke in sleep and attenuate treatment effectiveness during the active phase. This review underscores the importance of considering circadian biology for understanding the pathology and treatment choice for stroke and vascular dementia and speculates that considering a patient's chronotype may be an important factor in developing precision treatment following stroke.

Extending mechanical thrombectomy service provision to 24/7: a break-even analysis.

BACKGROUND: Comprehensive stroke centres across England have developed investment proposals, showing the estimated increases in mechanical thrombectomy (MT) treatment volume that would justify extending the standard hours to a 24/7 service provision. These investment proposals have been developed taking a financial accounting perspective, that is by considering the financial revenues from tariff income. However, given the pressure put on local health authorities to provide value for money services, an affordability question emerges. That is, at what additional MT treatment volume the additional treatment costs are offset by the additional health economic benefits, that is quality-adjusted life years (QALYs) and societal cost savings, generated by administering MT compared to standard care. METHODS: A break-even analysis was conducted to identify the additional MT treatment volume required. The incremental hospital-related costs associated with the 24/7 MT extension were estimated using information and parameters from four relevant business cases. The additional societal cost savings and health benefits were estimated by adapting a previously developed Markov chain-based model. RESULTS: The additional hospital-related annual costs for extending MT to a 24/7 service were estimated at a mean of £3,756,818 (range £1,847,387 to £5,092,788). On average, 750 (range 246 to 1,571) additional eligible stroke patients are required to be treated with MT yearly for the proposed 24/7 service extension to be affordable from a health economic perspective. Overall, the additional facility and equipment costs associated with the 24/7 extension would affect this estimate by 20%. CONCLUSIONS: These findings support the ongoing debate regarding the optimal levels of MT treatment required for a 24/7 extension and respective changes in hospital organisational activities. They also highlight a need for a regional-level coordination between local authorities and hospital administrations to ensure equity provision in that stroke patients can benefit from MT and that the optimal MT treatment volume is reached. Future studies should contemplate reproducing the presented analysis for different health service provision settings and decision making contexts.

Estimating the effectiveness and cost-effectiveness of establishing additional endovascular Thrombectomy stroke Centres in England: a discrete event simulation.

BACKGROUND: We have previously modelled that the optimal number of comprehensive stroke centres (CSC) providing endovascular thrombectomy (EVT) in England would be 30 (net 6 new centres). We now estimate the relative effectiveness and cost-effectiveness of increasing the number of centres from 24 to 30. METHODS: We constructed a discrete event simulation (DES) to estimate the effectiveness and lifetime cost-effectiveness (from a payer perspective) using 1 year's incidence of stroke in England. 2000 iterations of the simulation were performed comparing baseline 24 centres to 30. RESULTS: Of 80,800 patients admitted to hospital with acute stroke/year, 21,740 would be affected by the service reconfiguration. The median time to treatment for eligible early presenters (< 270 min since onset) would reduce from 195 (IQR 155-249) to 165 (IQR 105-224) minutes. Our model predicts reconfiguration would mean an additional 33 independent patients (modified Rankin scale [mRS] 0-1) and 30 fewer dependent/dead patients (mRS 3-6) per year. The net addition of 6 centres generates 190 QALYs (95%CI - 6 to 399) and results in net savings to the healthcare system of £1,864,000/year (95% CI -1,204,000 to £5,017,000). The estimated budget impact was a saving of £980,000 in year 1 and £7.07 million in years 2 to 5. CONCLUSION: Changes in acute stroke service configuration will produce clinical and cost benefits when the time taken for patients to receive treatment is reduced. Benefits are highly likely to be cost saving over 5 years before any capital investment above £8 million is required.

The exact science of stroke thrombolysis and the quiet art of patient selection.

The science of metric-based patient stratification for intravenous thrombolysis, revolutionized by the landmark National Institute of Neurological Disorders and Stroke trial, has transformed acute ischaemic stroke therapy. Recanalization of an occluded artery produces tissue reperfusion that unequivocally improves outcome and function in patients with acute ischaemic stroke. Recanalization can be achieved mainly through intravenous thrombolysis, but other methods such as intra-arterial thrombolysis or mechanical thrombectomy can also be employed. Strict guidelines preclude many patients from being treated by intravenous thrombolysis due to the associated risks. The quiet art of informed patient selection by careful assessment of patient baseline factors and brain imaging could increase the number of eligible patients receiving intravenous thrombolysis. Outside of the existing eligibility criteria, patients may fall into therapeutic 'grey areas' and should be evaluated on a case by case basis. Important factors to consider include time of onset, age, and baseline blood glucose, blood pressure, stroke severity (as measured by National Institutes of Health Stroke Scale) and computer tomography changes (as measured by Alberta Stroke Programme Early Computed Tomography Score). Patients with traditional contraindications such as wake-up stroke, malignancy or dementia may have the potential to receive benefit from intravenous thrombolysis if they have favourable predictors of outcome from both clinical and imaging criteria. A proportion of patients experience complications or do not respond to intravenous thrombolysis. In these patients, other endovascular therapies or a combination of both may be used to provide benefit. Although an evidence-based approach to intravenous thrombolysis for acute ischaemic stroke is pivotal, it is imperative to examine those who might benefit outside of protocol-driven practice.

Posterior circulation ischaemic stroke diagnosis and management.

This narrative review provides an overview of the posterior circulation and the clinical features of common posterior circulation stroke (PCS) syndromes in the posterior arterial territories and how to distinguish them from mimics. We outline the hyperacute management of patients with suspected PCS with emphasis on how to identify those who are likely to benefit from intervention based on imaging findings. Finally, we review advances in treatment options, including developments in endovascular thrombectomy (EVT) and intravenous thrombolysis (IVT), and the principles of medical management and indications for neurosurgery. Observational and randomised clinical trial data have been equivocal regarding EVT in PCS, but more recent studies strongly support its efficacy. There have been concomitant advances in imaging of posterior stroke to guide optimal patient selection for thrombectomy. Recent evidence suggests that clinicians should have a heightened suspicion of posterior circulation events with the resultant implementation of timely, evidence-based management.

The cost of providing mechanical thrombectomy in the UK NHS: a micro-costing study.

INTRODUCTION: The clinical efficacy and cost-effectiveness of mechanical thrombectomy (MT) for the treatment of large vessel occlusion stroke is well established, but uncertainty remains around the true cost of delivering this treatment within the NHS. The aim of this study was to establish the cost of providing MT within the hyperacute phase of care and to explore differences in resources used and costs across different neuroscience centres in the UK. METHOD: This was a multicentre retrospective study using micro-costing methods to enable a precise assessment of the costs of MT from an NHS perspective. Data on resources used and their costs were collected from five UK neuroscience centres between 2015 and 2018. RESULTS: Data were collected on 310 patients with acute ischaemic stroke treated with MT. The mean total cost of providing MT and inpatient care within 24 hours was £10,846 (95% confidence interval (CI) 10,527-11,165) per patient. The main driver of cost was MT procedure costs, accounting for 73% (£7,943; 95% CI 7,649-8,237) of the total 24-hour cost. Costs were higher for patients treated under general anaesthesia (£11,048; standard deviation (SD) 2,654) than for local anaesthesia (£9,978; SD 2,654), mean difference £1,070 (95% CI 381-1,759; p=0.003); admission to an intensive care unit (ICU; £12,212; SD 3,028) against for admission elsewhere (£10,179; SD 2,415), mean difference £2,032 (95% CI 1,345-2,719; p<0001).The mean cost within 72 hours was £12,440 (95% CI 10,628-14,252). The total costs for the duration of inpatient care before discharge from a thrombectomy centre was £14,362 (95% CI 13,603-15,122). CONCLUSIONS: Major factors contributing to costs of MT for stroke include consumables and staff for intervention, use of general anaesthesia and ICU admissions. These findings can inform the reimbursement, provision and strategic planning of stroke services and aid future economic evaluations.

Complications of endovascular treatment for acute ischemic stroke: Prevention and management.

Endovascular mechanical thrombectomy (MT) for the treatment of acute stroke due to large vessel occlusion has evolved significantly with the publication of multiple positive thrombectomy trials. MT is now a recommended treatment for acute ischemic stroke. Mechanical thrombectomy is associated with a number of intra-procedural or post-operative complications, which need to be minimized and effectively managed to maximize the benefits of thrombectomy. Procedural complications include: access-site problems (vessel/nerve injury, access-site hematoma and groin infection); device-related complications (vasospasm, arterial perforation and dissection, device detachment/misplacement); symptomatic intracerebral hemorrhage; subarachnoid hemorrhage; embolization to new or target vessel territory. Other complications include: anesthetic/contrast-related, post-operative hemorrhage, extra-cranial hemorrhage and pseudoaneurysm. Some complications are life-threatening and many lead to increased length of stay in intensive care and stroke units. Complications increase costs and delay the commencement of rehabilitation. Some may be preventable; the impact of others can be minimized with early detection and appropriate management. Both neurointerventionists and stroke specialists need to be aware of the risk factors, strategies for prevention, and management of these complications. With the increasing use of mechanical thrombectomy for the treatment of acute ischemic stroke, incidence and outcome of complications will need to be carefully monitored by stroke teams. In this narrative review, we examine the frequency of complications of MT in the treatment of acute ischemic stroke with an emphasis on periprocedural complications. Overall, from recent randomized controlled trials, the risk of complications with sequelae for patient from mechanical thrombectomy is ∼15%. We discuss the management of complications and identify areas with limited evidence, which need further research. Search strategy and selection criteria Relevant evidence was found by searches of Medline and Cochrane Library, reference list, cross-referencing and main journal content pages. Search terms included "brain ischemia", "acute ischemic stroke", "cerebral infarction" AND "mechanical thrombectomy", "endovascular therapy", "endovascular treatment", "endovascular embolectomy", "intra-arterial" AND "randomized controlled trial", "non-randomised trials", "observational studies" AND "complications", "procedural complications", "peri-procedural complications", "device-related complications", "management", "treatment", "outcome". The search included only human studies, and was limited to studies published in English between January 2014 and November 2016. The final reference list was selected on the basis of relevance to the topics covered in the Review. Guidelines for management of acute ischaemic stroke by the American Heart Association, the European Stroke Organisation, multi-disciplinary guidelines and the National Institute for Health and Care Excellence (NICE) were also reviewed.

The transient intraluminal filament middle cerebral artery occlusion model as a model of endovascular thrombectomy in stroke.

The clinical relevance of the transient intraluminal filament model of middle cerebral artery occlusion (tMCAO) has been questioned due to distinct cerebral blood flow profiles upon reperfusion between tMCAO (abrupt reperfusion) and alteplase treatment (gradual reperfusion), resulting in differing pathophysiologies. Positive results from recent endovascular thrombectomy trials, where the occluding clot is mechanically removed, could revolutionize stroke treatment. The rapid cerebral blood flow restoration in both tMCAO and endovascular thrombectomy provides clinical relevance for this pre-clinical model. Any future clinical trials of neuroprotective agents as adjuncts to endovascular thrombectomy should consider tMCAO as the model of choice to determine pre-clinical efficacy.

A systematic review and meta-analysis of randomized controlled trials of endovascular thrombectomy compared with best medical treatment for acute ischemic stroke.

BACKGROUND: Acute ischemic strokes involving occlusion of large vessels usually recanalize poorly following treatment with intravenous thrombolysis. Recent studies have shown higher recanalization and higher good outcome rates with endovascular therapy compared with best medical management alone. A systematic review and meta-analysis investigating the benefits of all randomized controlled trials of endovascular thrombectomy where at least 25% of patients were treated with a thrombectomy device for the treatment of acute ischemic stroke compared with best medical treatment have yet to be performed. AIM: To perform a systematic review and a meta-analysis evaluating the effectiveness of endovascular thrombectomy compared with best medical care for treatment of acute ischemic stroke. SUMMARY OF REVIEW: Our search identified 437 publications, from which eight studies (totaling 2423 patients) matched the inclusion criteria. Overall, endovascular thrombectomy was associated with improved functional outcomes (modified Rankin Scale 0-2) [odds ratio 1·56 (1·32-1·85), P < 0·00001]. There was a tendency toward decreased mortality [odds ratio 0·84 (0·67-1·05), P = 0·12], and symptomatic intracerebral hemorrhage was not increased [odds ratio 1·03 (0·71-1·49), P = 0·88] compared with best medical management alone. The odds ratio for a favorable functional outcome increased to 2·23 (1·77-2·81, P < 0·00001) when newer generation thrombectomy devices were used in greater than 50% of the cases in each trial. CONCLUSIONS: There is clear evidence for improvement in functional independence with endovascular thrombectomy compared with standard medical care, suggesting that endovascular thrombectomy should be considered the standard effective treatment alongside thombolysis in eligible patients.

Aneurysmal SAH: current management and complications associated with treatment and disease.

The purpose of this article is to give an overview of the management of the most common complications encountered during subarachnoid hemorrhage and endovascular treatment of intracranial aneurysms. We reviewed the literature and identified the complications encountered during endovascular treatment of intracranial aneurysms. We report current management strategies of complications associated with subarachnoid hemorrhage and the interventional procedure. Aneurysmal subarachnoid hemorrhage remains a devastating condition, with high mortality and poor outcome among survivors. The successful treatment of intracranial aneurysms requires a multidisciplinary approach and the treating physicians need to be aware of predisposing factors for complications, their frequency, and also their management.

Proximal protection with the Gore PAES can reduce DWI lesion size in high-grade stenosis during carotid stenting.

AIMS: The aim was to determine the incidence of new ischaemic lesions on diffusion-weighted MR imaging (DWI) in a non-randomised cohort of patients after protected and unprotected carotid artery stent placement using the Parodi Anti-Emboli System (PAES). METHODS AND RESULTS: A retrospective review was conducted on 269 patients who received DWI prior to, and 24-72 hours after, stent placement. All patients were enrolled in one centre. Forty patients stented with the PAES device were matched with 229 patients stented without protection (control group). New diffusion restriction on DWI was detected in 25.8% (PAES) versus 32.3% (control group); p=0.64. On average there were 0.7 lesions (PAES) versus 0.8 lesions (control group) per patient. The area of lesions was 1.7 (PAES) versus 5.6 mm2. In a subanalysis of patients (32 PAES, 148 non-protected) with >80% stenosis, the area of restricted diffusion was less when proximal protection was used (p<0.05). The number and area of DWI lesions did not differ on the contralateral, non-stented side. When the PAES system was used, patients were more likely not to have any lesion at all (p=0.028). CONCLUSIONS: In high-grade stenosis, the use of the Gore PAES device significantly reduced the area of new DWI lesions and patients were more likely not to have any new DWI lesion at all.

Complications associated with recombinant tissue plasminogen activator therapy for acute ischaemic stroke.

Intravenous recombinant human tissue plasminogen activator (rtPA, formulated as alteplase) is the primary therapy for acute ischaemic stroke by breaking down a clot of an occluded vessel. There are several randomised controlled trials and observational studies that support the use of rtPA to improve functional outcome following acute ischaemic stroke. However, thrombolytic therapy with rtPA can be associated with a number of complications. Many of the rtPArelated complications result from its thrombolytic action including bleeding (intracerebral and systemic haemorrhage), reperfusion injury with oedema, and angioedema. Other rtPA complications such as reocclusion and secondary embolisation are related to ineffective thrombolysis or redistribution of the lysed clot. In addition to its thrombolytic properties, rtPA can act upon the brain parenchyma leading to seizures and neurotoxicity. Many of these complications have been reported in both pre-clinical experiments and in clinical trials. In animal studies, these complications of rtPA can confound the experimental results achieved, and have to be taken into account in future experiments. In the clinical setting, these complications are not always life-threatening, but can be serious and often lead to prolonged stays in intensive care units, increase the need for medical treatment, lengthen hospital stays, delay rehabilitation and increase morbidity and mortality. Some of these complications could be prevented through adherence to treatment guidelines or at least minimised through early detection and proper management. It is imperative that physicians caring for stroke patients have knowledge of these complications associated with rtPA treatment, and their management.

Stem cell therapy for ischaemic stroke: translation from preclinical studies to clinical treatment.

No pharmacological intervention has been shown convincingly to improve neurological outcome in stroke patients after the brain tissue is infarcted. While conventional therapeutic strategies focus on preventing brain damage, stem cell treatment has the potential to repair the injured brain tissue. Stem cells not only produce a source of trophic molecules to minimize brain damage caused by ischaemia/reperfusion and promote recovery, but also potentially turn to new cells to replace those lost in ischaemic core. Although preclinical studies have shown promise, stem cell therapy for stroke treatment in human is still at an early stage and it is difficult to draw conclusions from current clinical trials about the efficacy of the different treatments used in humans. This article reviews the potential of various types of stem cells, from embryonic to adult to induced pluripotent stem cells, in stroke therapy, highlights new evidence from the ongoing clinical trials and discusses some of the problems associated with translating stem cell technology to a clinical therapy for stroke.

Thrombolytic agents for acute ischaemic stroke treatment: the past, present and future.

Despite advances in the diagnosis and treatment of acute ischaemic stroke in the past two decades, stroke has remained the third cause of mortality and the single leading cause of disability worldwide. The immediate goal of acute ischaemic stroke therapy is to salvage the ischaemic penumbra through recanalisation of the occluded cerebral blood vessel. This is currently achieved through thrombolytics, which are pharmacological agents that can break up a clot blocking the flow of blood. To date, the only approved thrombolytic for treatment of acute ischaemic stroke is recombinant tissue plasminogen activator (alteplase, rt-PA), however, alteplase is substantially underused because of concerns regarding adverse bleeding risk. This limitation has fuelled the search for other thrombolytic agents, which display greater fibrin dependence and selectivity, but lack detrimental effects within the central nervous system. Development of alternative fibrinolytic agents that might be easier and safer to administer could lead to wider acceptance and use of thrombolytic therapy for stroke. Although other thrombolytic agents (e.g. streptokinase) have failed to show benefit over alteplase, there is still on-going research in search of alternative agents with higher target specificity and better safety profile. The potential thrombolytic agents with trials in progress include desmoteplase, tenecteplase, reteplase, plasmin and microplasmin. This review summarises current therapies with thrombolytics (e.g. alteplase and urokinase), their limitations and side effects, and also discusses ongoing clinical studies with the various potential emerging thrombolytic agents.

Different factors influence recanalisation rate after coiling in ruptured and unruptured intracranial aneurysms.

BACKGROUND: Most studies evaluating long-term efficacy after coil embolisation of intracranial aneurysms have not differentiated between ruptured and unruptured aneurysms. OBJECTIVES: The aim of this study was to analyse factors that influence recanalisation in ruptured and unruptured aneurysms. METHODS: We performed a retrospective analysis of 182 (98 ruptured, 84 unruptured) aneurysms, treated with coil embolisation alone that received follow-up with digital substraction angiography (DSA). RESULTS: At 6 months 26% of the aneurysms showed recanalisation. Multivariate variance analysis revealed that different factors influenced recanalisation in ruptured and unruptured aneurysms. In ruptured aneurysms patient age was a determinant, with younger patients recanalising more frequently than older ones (p = 0.016). Also, low initial packing density led to higher recanalisation rates (p = 0.015) than higher packing. In the unruptured aneurysm group these factors were not significant. Here, only a larger aneurysm volume led to higher recanalisation rates (p = 0.027). CONCLUSIONS: Our data suggest that in ruptured aneurysms, high packing density is a key factor to prevent recanalisation, while in unruptured aneurysms, aneurysm volume is the main predictor for recanalisation.

Complications of intracerebral haemorrhage.

Intracerebral haemorrhage (ICH) is the most devastating type of stroke and is a leading cause of disability and mortality. By contrast with advances in ischaemic stroke treatment, few evidence-based targeted treatments exist for ICH. Management of ICH is largely supportive, with strategies aimed at the limitation of further brain injury and the prevention of associated complications, which add further detrimental effects to an already lethal disease and jeopardise clinical outcomes. Complications of ICH include haematoma expansion, perihaematomal oedema with increased intracranial pressure, intraventricular extension of haemorrhage with hydrocephalus, seizures, venous thrombotic events, hyperglycaemia, increased blood pressure, fever, and infections. In view of the restricted number of therapeutic options for patients with ICH, improved surveillance is needed for the prevention of these complications, or, when this is not possible, early detection and optimum management, which could be effective in the reduction of adverse effects early in the course of stroke and in the improvement of prognosis. Further studies are needed to enhance the evidence-based recommendations for the management of this important clinical problem.

"Stroke Nav": a wireless data collection and review system to support stroke care delivery.

"Stroke Nav" is a novel system to support the care of stroke patients. The system contains purpose-built web-based software to facilitate accurate near-real time data collection by clinicians throughout the complex care settings traversed by patients. Tools are included to facilitate pre-defined and bespoke data review with graphical dashboards showing performance metrics and other aggregate data. The software was designed collaboratively by health care professionals and engineers, and is accessible via the hospital intranet using desktop or laptop computers and wireless mobile devices. Stroke Nav is being routinely used in two hospitals, with over 1400 patients registered, and is now being introduced in other hospitals. The system is delivering benefits in relation to multidisciplinary communication, knowledge management, patient safety, clinical audit and service performance.

Neuroprotection for ischaemic stroke: translation from the bench to the bedside.

Neuroprotection seeks to restrict injury to the brain parenchyma following an ischaemic insult by preventing salvageable neurons from dying. The concept of neuroprotection has shown promise in experimental studies, but has failed to translate into clinical success. Many reasons exist for this including the heterogeneity of human stroke and the lack of methodological agreement between preclinical and clinical studies. Even with the proposed Stroke Therapy Academic Industry Roundtable criteria for preclinical development of neuroprotective agents for stroke, we have still seen limited success in the clinic, an example being NXY-059, which fulfilled nearly all the Stroke Therapy Academic Industry Roundtable criteria. There are currently a number of ongoing trials for neuroprotective strategies including hypothermia and albumin, but the outcome of these approaches remains to be seen. Combination therapies with thrombolysis also need to be fully investigated, as restoration of oxygen and glucose will always be the best therapy to protect against cell death from stroke. There are also a number of promising neuroprotectants in preclinical development including haematopoietic growth factors, and inhibitors of the nicotinamide adenine dinucleotide phosphate oxidases, a source of free radical production which is a key step in the pathophysiology of acute ischaemic stroke. For these neuroprotectants to succeed, essential quality standards need to be adhered to; however, these must remain realistic as the evidence that standardization of procedures improves translational success remains absent for stroke.