Design and Validation of a Prehospital Stroke Scale to Predict Large Arterial Occlusion

Society of Vascular and Interventional Neurology (SVIN) Stroke Interventional Laboratory Consensus (SILC) Criteria: A 7M Management Approach to Developing a Stroke Interventional Laboratory in the Era of Stroke Thrombectomy for Large Vessel Occlusions

Brain attack care is rapidly evolving with cutting-edge stroke interventions similar to the growth of heart attack care with cardiac interventions in the last two decades. As the field of stroke intervention is growing exponentially globally, there is clearly an unmet need to standardize stroke interventional laboratories for safe, effective, and timely stroke care. Towards this goal, the Society of Vascular and Interventional Neurology (SVIN) Writing Committee has developed the Stroke Interventional Laboratory Consensus (SILC) criteria using a 7M management approach for the development and standardization of each stroke interventional laboratory within stroke centers. The SILC criteria include: (1) manpower: personnel including roles of medical and administrative directors, attending physicians, fellows, physician extenders, and all the key stakeholders in the stroke chain of survival; (2) machines: resources needed in terms of physical facilities, and angiography equipment; (3) materials: medical device inventory, medications, and angiography supplies; (4) methods: standardized protocols for stroke workflow optimization; (5) metrics (volume): existing credentialing criteria for facilities and stroke interventionalists; (6) metrics (quality): benchmarks for quality assurance; (7) metrics (safety): radiation and procedural safety practices.

Bypassing primary stroke centre reduces delay and improves outcomes for patients with large vessel occlusion

Objective

In large-vessel occlusion, endovascular therapy is superior to medical management alone in achieving recanalisation. Reducing time delays to revascularisation in patients with large-vessel occlusion is important to improving outcome.

Patients and methods

A campaign was implemented in the Central Denmark Region targeting the identification of patients with large-vessel occlusion for direct transport to a comprehensive stroke centre. Time delays and outcomes before and after the intervention were assessed.

Results

A total of 476 patients (153 pre-intervention and 323 post-intervention) were included. They were treated with either intravenous tissue plasminogen activator or endovascular treatment (alone or in combination with intravenous tissue plasminogen activator). Endovascular therapy patients' median system delay was reduced from 234 to 185 min (adjusted relative risk delay 0.79 (95% confidence interval: 0.67-0.93)). The in-hospital delay was the main driver with an adjusted relative risk delay of 0.76 (confidence interval: 0.62-0.94), while pre-hospital delay was almost significantly reduced with an adjusted relative delay of 0.86 (confidence interval: 0.71-1.04). This was achieved without increasing the intravenous tissue plasminogen activator-treated patients' delay. Significantly more patients treated with endovascular therapy in the post-interventional period achieved functional independence (62% versus 43%), corresponding to an adjusted odds ratio of 3.08 (95% confidence interval: 1.08-8.78).

Conclusion

Direct transfer of patients with suspected large-vessel occlusion to a comprehensive stroke centre leads to shorter treatment times for endovascular therapy patients and is, in turn, associated with an increase in functional independence. We recorded no adverse effects on intravenous tissue plasminogen activator treatment times or outcome.

Changing Management of Acute Ischaemic Stroke: the New Treatments and Emerging Role of Endovascular Therapy

OPINION STATEMENT

Urgent reperfusion of the ischaemic brain is the aim of stroke treatment, and the last two decades have seen a rapid advancement in the medical and endovascular treatment of acute ischaemic stroke. Intravenous tissue plasminogen activator (tPA) was first introduced as a safe and effective thrombolytic agent followed by the introduction of newer thrombolytic agents as well as anticoagulant and antiplatelet agents, proposed as potentially safer drugs with more favourable interaction profiles. In addition to chemo-thrombolysis, other techniques including transcranial sonothrombolysis and microbubble cavitation have been introduced which are showing promising results, but await large-scale clinical trials. These developments in medical therapies which are undoubtedly of great importance due to their potential widespread and immediate availability are paralleled with gradual but steady improvements in endovascular recanalisation techniques which were initiated by the introduction of the MERCI (Mechanical Embolus Removal in Cerebral Ischemia) and Penumbra systems. The introduction of the Solitaire device was a significant achievement in reliable and safe endovascular recanalisation and was followed by further innovative stent retrievers. Initial trials failed to show a solid benefit in endovascular intervention compared with IV-tPA alone. These counterintuitive results did not last long, however, when a series of very well-designed randomised controlled trials, pioneered by MR-CLEAN, EXTEND-IA and ESCAPE, emerged, confirming the well-believed daily anecdotal evidence. There have now been seven positive trials of endovascular treatment for acute ischaemic stroke. Now that level I evidence regarding the superiority of endovascular recanalisation is abundantly available, the clinical challenge is how to select patients suitable for intervention and to familiarise and educate stroke care providers with this recent development in stroke care. It is important for the interventional services to be provided only in comprehensive stroke centres and endovascular interventions attempted by experienced well-trained operators, at this stage as an adjunct to the established medical treatment of IV-tPA, if there are no contraindications.

External Validation of the Cincinnati Prehospital Stroke Severity Scale

BACKGROUND

The Cincinnati Prehospital Stroke Severity Scale (CPSSS) was recently developed to predict large-vessel occlusions (LVOs) in patients with acute ischemic stroke (AIS). In its derivation study, which consisted of patients enrolled in thrombolysis and endovascular therapy trials, the CPSSS had excellent discriminatory performance. We sought to externally validate the CPSSS in an independent cohort.

METHODS

Using our institution's prospective stroke registry, we calculated CPSSS scores for all patients diagnosed with AIS at Weill Cornell Medical Center in 2013 and 2014. The primary outcome was presence of LVO and the secondary outcome was a National Institutes of Health Stroke Scale (NIHSS) score of 15 or higher. Harrell's c-statistic was calculated to determine the CPSSS score's discriminatory performance. Using the previously defined cut-point of 2 or higher (range 0-4), we evaluated the test properties of the CPSSS for predicting study outcomes.

RESULTS

Among 751 patients with AIS, 664 had vessel imaging and were included in the final analysis. Of these patients, 80 (14.2%) had LVOs and 117 (17.6%) had an NIHSS score of 15 or higher. The median CPSSS score was 0 (interquartile range 0-1) and 133 patients (20%) had scores of 2 or higher. c-statistic was .85 (95% confidence interval [CI] .81-.90) for predicting LVO and .94 (95% CI .92-.97) for predicting an NIHSS score of 15 or higher. Using a cut-point of 2 or higher, the CPSSS was 70.0% sensitive and 86.8% specific for predicting LVO, and 87.2% sensitive and 94.3% specific for predicting an NIHSS score of 15 or higher.

CONCLUSIONS

In a cohort of patients with AIS treated at a tertiary-care stroke center, the CPSSS had reasonable sensitivity and specificity for predicting LVO and severe stroke. Future studies should aim to prospectively validate the score in emergency responders.

Developing a statewide protocol to ensure patients with suspected emergent large vessel occlusion are directly triaged in the field to a comprehensive stroke center: how we did it

We describe the process by which we developed a statewide field destination protocol to transport patients with suspected emergent large vessel occlusion to a comprehensive stroke center.

Acute Stroke: Current Evidence-based Recommendations for Prehospital Care

Introduction

In the United States, emergency medical services (EMS) protocols vary widely across jurisdictions. We sought to develop evidence-based recommendations for the prehospital evaluation and treatment of a patient with a suspected stroke and to compare these recommendations against the current protocols used by the 33 EMS agencies in the state of California.

Methods

We performed a literature review of the current evidence in the prehospital treatment of a patient with a suspected stroke and augmented this review with guidelines from various national and international societies to create our evidence-based recommendations. We then compared the stroke protocols of each of the 33 EMS agencies for consistency with these recommendations. The specific protocol components that we analyzed were the use of a stroke scale, blood glucose evaluation, use of supplemental oxygen, patient positioning, 12-lead electrocardiogram (ECG) and cardiac monitoring, fluid assessment and intravenous access, and stroke regionalization.

Results

Protocols across EMS agencies in California varied widely. Most used some sort of stroke scale with the majority using the Cincinnati Prehospital Stroke Scale (CPSS). All recommended the evaluation of blood glucose with the level for action ranging from 60 to 80mg/dL. Cardiac monitoring was recommended in 58% and 33% recommended an ECG. More than half required the direct transport to a primary stroke center and 88% recommended hospital notification.

Conclusion

Protocols for a patient with a suspected stroke vary widely across the state of California. The evidence-based recommendations that we present for the prehospital diagnosis and treatment of this condition may be useful for EMS medical directors tasked with creating and revising these protocols.

Mechanical Thrombectomy-Ready Comprehensive Stroke Center Requirements and Endovascular Stroke Systems of Care: Recommendations from the Endovascular Stroke Standards Committee of the Society of Vascular and Interventional Neurology (SVIN)

Five landmark multicenter, prospective, randomized, open-label, blinded end point clinical trials have recently demonstrated significant clinical benefit of endovascular therapy with mechanical thrombectomy in acute ischemic stroke (AIS) patients presenting with proximal intracranial large vessel occlusions. The Society of Vascular and Interventional Neurology (SVIN) appointed an expert writing committee to summarize this new evidence and make recommendations on how these data should guide emergency endovascular therapy for AIS patients.

Stroke vision, aphasia, neglect (VAN) assessment-a novel emergent large vessel occlusion screening tool: pilot study and comparison with current clinical severity indices

Background

Identification of emergent large vessel occlusion (ELVO) stroke has become increasingly important with the recent publications of favorable acute stroke thrombectomy trials. Multiple screening tools exist but the length of the examination and the false positive rate range from good to adequate. A screening tool was designed and tested in the emergency department using nurse responders without a scoring system.

Methods

The vision, aphasia, and neglect (VAN) screening tool was designed to quickly assess functional neurovascular anatomy. While objective, there is no need to calculate or score with VAN. After training participating nurses to use it, VAN was used as an ELVO screen for all stroke patients on arrival to our emergency room before physician evaluation and CT scan.

Results

There were 62 consecutive code stroke activations during the pilot study. 19 (31%) of the patients were VAN positive and 24 (39%) had a National Institutes of Health Stroke Scale (NIHSS) score of ≥6. All 14 patients with ELVO were either VAN positive or assigned a NIHSS score ≥6. While both clinical severity thresholds had 100% sensitivity, VAN was more specific (90% vs 74% for NIHSS ≥6). Similarly, while VAN and NIHSS ≥6 had 100% negative predictive value, VAN had a 74% positive predictive value while NIHSS ≥6 had only a 58% positive predictive value.

Conclusions

The VAN screening tool accurately identified ELVO patients and outperformed a NIHSS ≥6 severity threshold and may best allow clinical teams to expedite care and mobilize resources for ELVO patients. A larger study to both validate this screening tool and compare with others is warranted.

Advances in endovascular therapy for ischemic stroke

Purpose of review:

The burden of disability from ischemic stroke continues to intensify. Any acute therapeutic option that reduces disability after ischemic stroke should be encouraged and further studied. In particular, the need for an effective treatment in patients with large vessel occlusion has been long overdue.

Recent findings:

Consistent trial evidence has answered this need in an emphatic fashion, demonstrating improved functional outcomes with endovascular therapy following better patient selection, new device technology, and reduced treatment times. The article discusses the current evidence and guidelines and highlights the inherent complexities of a specialized intervention whose demand will grow exponentially. The scope for future investigation especially using advanced imaging to expand patient selection will be considered.

Summary:

Endovascular thrombectomy is an established and highly efficacious acute treatment for ischemic stroke that we need to apply and implement to maximize benefit to the population.

The Possible Role of Toll-Like Receptor 4 in the Pathology of Stroke

Stroke is a prevalent and dangerous health problem, which triggers an intense inflammatory response to Toll-like receptor (TLR) activation. TLRs are the essential components of the response of the innate immunity system, and, therefore, they are one of the key factors involved in recognizing pathogens and internal ligands. Among TLRs, TLR4 significantly participates in the induction of inflammation and brain functions; hence, it has been hypothesized that this molecule is associated with several immune-related brain diseases such as stroke. It has also been proved that animals with TLR4 deficiency have higher protection against ischemia and that the absence of TLR4 reduces neuroinflammation and injuries associated with brain trauma. TLR4 deficiency may play a neuroprotective role in the occurrence of stroke. This article reviews recent information regarding the impact of TLR4 on the pathogenicity of stroke.

Severe hemiparesis as a prehospital tool to triage stroke severity: a pilot study to assess diagnostic accuracy and treatment times

INTRODUCTION

With the publication of the recent trials showing the tremendous benefits of mechanical thrombectomy, opportunities exist to refine prehospital processes to identify patients with larger stroke syndromes.

MATERIALS AND METHODS

We retrospectively reviewed consecutive patients who were brought via scene flight from rural parts of the region to our institution, from December 1, 2014 to June 5, 2015, with severe hemiparesis or hemiplegia. We assessed the accuracy of the diagnosis of stroke and the number of patients requiring endovascular therapy. Moreover, we reviewed the times along the pathway of patients who were treated with endovascular therapy.

RESULTS

45 patients were brought via helicopter from the field to our institution. 27 (60%) patients were diagnosed with an ischemic stroke. Of these, 12 (26.7%) were treated with mechanical thrombectomy and 6 (13.3%) with intravenous tissue plasminogen activator alone. An additional three patients required embolization procedures for either a dural arteriovenous fistula or cerebral aneurysm. Thus a total of 15 (33%) patients received an endovascular procedure and 21/45 (46.7%) received an acute treatment. For patients treated with thrombectomy, the median time from first medical contact to groin puncture was 101 min, with 8 of the 12 patients (66.7%) being discharged to home.

CONCLUSIONS

We have presented a pilot study showing that severe hemiparesis or hemiplegia may be a reasonable prehospital tool in recognizing patients requiring endovascular treatment. Patients being identified earlier may be treated faster and potentially improve outcomes. Further prospective controlled studies are required to assess the impact on outcomes and cost effectiveness using this methodology.

Endovascular stent thrombectomy: the new standard of care for large vessel ischaemic stroke

BACKGROUND

Results of initial randomised trials of endovascular treatment for ischaemic stroke, published in 2013, were neutral but limited by the selection criteria used, early-generation devices with modest efficacy, non-consecutive enrollment, and treatment delays.

RECENT DEVELOPMENTS

In the past year, six positive trials of endovascular thrombectomy for ischaemic stroke have provided level 1 evidence for improved patient outcome compared with standard care. In most patients, thrombectomy was performed in addition to thrombolysis with intravenous alteplase, but benefits were also reported in patients ineligible for alteplase treatment. Despite differences in the details of eligibility requirements, all these trials required proof of major vessel occlusion on non-invasive imaging and most used some imaging technique to exclude patients with a large area of irreversibly injured brain tissue. The results indicate that modern thrombectomy devices achieve faster and more complete reperfusion than do older devices, leading to improved clinical outcomes compared with intravenous alteplase alone. The number needed to treat to achieve one additional patient with independent functional outcome was in the range of 3·2-7·1 and, in most patients, was in addition to the substantial efficacy of intravenous alteplase. No major safety concerns were noted, with low rates of procedural complications and no increase in symptomatic intracerebral haemorrhage. WHERE NEXT?: Thrombectomy benefits patients across a range of ages and levels of clinical severity. A planned meta-analysis of individual patient data might clarify effects in under-represented subgroups, such as those with mild initial stroke severity or elderly patients. Imaging-based selection, used in some of the recent trials to exclude patients with large areas of irreversible brain injury, probably contributed to the proportion of patients with favourable outcomes. The challenge is how best to implement imaging in clinical practice to maximise benefit for the entire population and to avoid exclusion of patients with smaller yet clinically important potential to benefit. Although favourable imaging identifies patients who might benefit despite long delays from symptom onset to treatment, the proportion of patients with favourable imaging decreases with time. Health systems therefore need to be reorganised to deliver treatment as quickly as possible to maximise benefits. On the basis of available trial data, intravenous alteplase remains the initial treatment for all eligible patients within 4·5 h of stroke symptom onset. Those patients with major vessel occlusion should, in parallel, proceed to endovascular thrombectomy immediately rather than waiting for an assessment of response to alteplase, because minimising time to reperfusion is the ultimate aim of treatment.

Design and validation of a prehospital scale to predict stroke severity: Cincinnati Prehospital Stroke Severity Scale

BACKGROUND AND PURPOSE

We derived and validated the Cincinnati Prehospital Stroke Severity Scale (CPSSS) to identify patients with severe strokes and large vessel occlusion (LVO).

METHODS

CPSSS was developed with regression tree analysis, objectivity, anticipated ease in administration by emergency medical services personnel and the presence of cortical signs. We derived and validated the tool using the 2 National Institute of Neurological Disorders and Stroke (NINDS) tissue-type plasminogen activator Stroke Study trials and Interventional Management of Stroke III (IMS III) Trial cohorts, respectively, to predict severe stroke (National Institutes of Health Stroke Scale [NIHSS]≥15) and LVO. Standard test characteristics were determined and receiver operator curves were generated and summarized by the area under the curve.

RESULTS

CPSSS score ranges from 0 to 4; composed and scored by individual NIHSS items: 2 points for presence of conjugate gaze (NIHSS≥1); 1 point for presence of arm weakness (NIHSS≥2); and 1 point for presence abnormal level of consciousness commands and questions (NIHSS level of consciousness≥1 each). In the derivation set, CPSSS had an area under the curve of 0.89; score≥2 was 89% sensitive and 73% specific in identifying NIHSS≥15. Validation results were similar with an area under the curve of 0.83; score≥2 was 92% sensitive, 51% specific, a positive likelihood ratio of 3.3, and a negative likelihood ratio of 0.15 in predicting severe stroke. For 222 of 303 IMS III subjects with LVO, CPSSS had an area under the curve of 0.67; a score≥2 was 83% sensitive, 40% specific, positive likelihood ratio of 1.4, and negative likelihood ratio of 0.4 in predicting LVO.

CONCLUSIONS

CPSSS can identify stroke patients with NIHSS≥15 and LVO. Prospective prehospital validation is warranted.