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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Stroke syndromes and clinical management

The knowledge of brain syndromes is essential for stroke physicians and neurologists, particularly those that can be extremely difficult and challenging to diagnose due to the great variability of symptom presentation and yet of clinical significance in terms of potential devastating effect with poor outcome. The diagnosis and understanding of stroke syndromes has improved dramatically over the years with the advent of modern imaging, while the management is similar to general care as recommended by various guidelines in addition to care of such patients on specialized units with facilities for continuous monitoring of vital signs and dedicated stroke therapy. Such critical care can be provided either in the acute stroke unit, the medical intensive care unit or the neurological intensive care unit. There may be no definitive treatment at reversing stroke syndromes, but it is important to identify the signs and symptoms for an early diagnosis to prompt quick treatment, which can prevent further devastating complications following stroke. The aim of this article is to discuss some of the important clinical stroke syndromes encountered in clinical practice and discuss their management.

"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.

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.

Endovascular stroke treatment today

The purpose of this study was to review current treatment options in acute ischemic stroke, focusing on the latest advances in the field of mechanical recanalization. These devices recently made available for endovascular intracranial thrombectomy show great potential in acute stroke treatments. Compelling evidence of their recanalization efficacy comes from current mechanical embolectomy trials. In addition to allowing an extension of the therapeutic time window, mechanical recanalization devices can be used without adjuvant thrombolytic therapy, thus diminishing the intracranial bleeding risk. Therefore, these devices are particularly suitable in patients in whom thrombolytic therapy is contraindicated. IV and IA thrombolysis and bridging therapy are viable options in acute stroke treatment. Mechanical recanalization devices can potentially have a clinically relevant impact in the interventional treatment of stroke, but at the present time, a randomized study would be beneficial.

Neurological complications of acute ischaemic stroke

Complications after ischaemic stroke, including both neurological and medical complications, are a major cause of morbidity and mortality. Neurological complications, such as brain oedema or haemorrhagic transformation, occur earlier than do medical complications and can affect outcomes with potential serious short-term and long-term consequences. Some of these complications could be prevented or, when this is not possible, early detection and proper management could be effective in reducing the adverse effects. However, there is little evidence-based data to guide the management of these neurological complications. There is a clear need for improved surveillance and specific interventions for the prevention, early diagnosis, and proper management of neurological complications during the acute phase of stroke to reduce stroke morbidity and mortality.

Ischemic stroke in the elderly: an overview of evidence

Stroke mostly occurs in elderly people and patient outcomes after stroke are highly influenced by age. A better understanding of the causes of stroke in the elderly might have important practical implications not only for clinical management, but also for preventive strategies and future health-care policies. In this Review, we explore the evidence from both human and animal studies relating to the effect of old age-in terms of susceptibility, patient outcomes and response to treatment-on ischemic stroke. Several aging-related changes in the brain have been identified that are associated with an increase in vulnerability to ischemic stroke in the elderly. Furthermore, risk factor profiles for stroke and mechanisms of ischemic injury differ between young and elderly patients. Elderly patients with ischemic stroke often receive less-effective treatment and have poorer outcomes than younger individuals who develop this condition. Neuroprotective agents for ischemic stroke have been sought for decades but none has proved effective in humans. One contributing factor for this translational failure is that most preclinical studies have used young animals. Future research on ischemic stroke should consider age as a factor that influences stroke prevention and treatment, and should focus on the management of acute stroke in the elderly to reduce the incidence and improve outcomes in this vulnerable group.