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Finding ELVO: New Stroke Scales for EMS
Editor’s note: This is the second of a three-part special series on the pivotal and evolving role of EMS in stroke care. Last month the authors discussed decision-making criteria informing the ideal destinations to transport patients with stroke symptoms and profiled novel partnerships between EMS systems and stroke centers. In next month’s issue, the authors describe the critical function of state stroke registries and how EMS agencies can help enable timely and efficient in-hospital care.
Before the landmark trials of 20151–5 ushered in a new era for acute stroke treatment for patients with emergent large-vessel occlusion (ELVO), IV thrombolysis with the clot-busting medication IV tPA was the only option. The effectiveness of this medication was predominantly limited to small-vessel strokes, and it was approved by the FDA to be given within three hours of stroke onset.6 Furthermore, its benefit is time-dependent—the earlier the treatment can be administered, the better the potential outcome. As a result, stroke centers developed prehospital protocols aimed at EMS integration to ensure information communicated via a stroke alert could permit early preparedness for evaluation and treatment.
Studies have shown EMS stroke alerts significantly reduce times to treatment with IV tPA in eligible patients while increasing treatment rates.7 Traditional prehospital stroke scales such as the Cincinnati Prehospital Stroke Scale (CPSS) and Los Angeles Prehospital Stroke Screen (LAPSS) were designed to detect small-vessel strokes for appropriate triage to stroke centers capable of delivering IV tPA. However, their utility is limited for detection of ELVO strokes, which tend to be more severe than small-vessel strokes.
Strokes due to ELVO have the potential to cause significant compromise of blood flow to the affected region, particularly within the cortex, or surface of the brain responsible for advanced neurological functions. Concurrently with positive mechanical thrombectomy trials making this treatment a standard of care for ELVO, several new prehospital stroke scales have been developed to assist EMS with prehospital evaluation of suspected ELVO patients and triage to a thrombectomy-capable hospital. The RACE, Stroke VAN, FAST-ED, C-STAT and LAMS are examples of prehospital ELVO scales that include assessment for specific cortical signs such as gaze preference, aphasia and neglect in addition to the limb weakness included in previous small-vessel stroke scales.
Here are looks at each of these new scales.
I. RACE
The Rapid Arterial oCclusion Evaluation (RACE) scale is scored on a range of 0–9, with higher scores conferring greater probability of ELVO. The scale evaluates face, arm and leg weakness, followed by presence of cortical signs. A score of 5 or higher has been shown to identify 85% of patients with ELVO.8 In this study EMS performed field assessment for stroke using the RACE scale, and TCD (transcranial Doppler) or CT angiography scans were used upon ER arrival to confirm presence of ELVO. As a result of the implications for EMS triage to the most appropriate facility for thrombectomy, the RACE scale is being broadly adopted as part of prehospital stroke protocols.
Memorial Healthcare in South Florida, a six-hospital system, was among the first stroke networks to implement the RACE scale for EMS alerts. The scale was deployed in the fall of 2015, with a lead-in phase of four months to allow for education and training of the eight EMS agencies serving the Memorial patient catchment area. All medics were instructed to provide a RACE score as part of their stroke alert protocol. A quality improvement initiative was then launched at Memorial’s two comprehensive stroke centers to prospectively track data on all EMS stroke alerts. When an EMS RACE score was 5 or higher, the cath lab team was notified prior to EMS arrival in anticipation of possible mechanical thrombectomy, mirroring the process already in place for code hearts (Figure 1).
From January 2016 to June 2017, there were 1,498 EMS stroke alerts, and the RACE score was provided for 670 patients (45%). Each stroke alert patient received a CTA of the head/neck upon ER arrival to assess for ELVO, which was found in 103 patients with an available RACE score. A RACE score of 5 or higher identified 66% of all ELVO patients. Mechanical thrombectomy was performed for 78% of patients with RACE scores of 5 or higher who had ELVO and 46% of those with RACE scores less than 5. Reasons for not performing thrombectomy despite ELVO were the large size of the stroke, significant exam improvement or poor baseline function. When an EMS stroke alert with high RACE score triggered early notification of the cath lab team, the median door-to-groin-puncture time for thrombectomy was 65 minutes, compared to 98 minutes for cases without an EMS stroke alert.
The Memorial data on EMS RACE use and its parallel in-hospital workflow provides several insights. The RACE scale was found to be a reliable tool for the prehospital evaluation of possible ELVO strokes, and when it was combined with a protocol for early notification of the cath lab team, a significant reduction in time to treatment was achieved. The reliability of any clinical scale is based on the experience of the examiner performing the evaluation. Therefore, ongoing EMS education is critical to proper identification of potential ELVO strokes. In our experience the accuracy of the RACE scale was determined based on its correlation with the National Institutes of Health Stroke Scale (NIHSS) on arrival at the ER, and thus the scale was utilized to guide EMS stroke training on a quarterly basis.
Some notable pitfalls of the RACE score include its emphasis on motor impairment more than cortical signs, which can result in a higher false-positive rate of triage to CSCs and early activation of cath lab teams. For example, weakness of the face, arm and leg can also be seen in small-vessel strokes but could combine for a RACE score greater than 5. Additionally, cortical signs receive fewer points overall than limb weakness and, when combined with the association of agnosia versus aphasia based on side of weakness in the RACE scale, may lead to underestimation of stroke severity. Gaze preference, which has been shown to be the strongest predictor for ELVO, is only assigned one point on the scale. Finally, aphasia is only partially evaluated in the RACE scale, as it tests ability to follow commands but not speech.
Due to these limitations, we recently modified the RACE scale (Figure 2) by adding a plus sign next to the score to denote the presence of any cortical signs. We hope this improves EMS triage of potential ELVO patients to CSCs. We expanded aphasia testing to include the expressive component for speech evaluation. EMS was also instructed to evaluate for aphasia and neglect regardless of the side of arm/leg weakness.
The rationale for focusing on cortical signs is supported by our data from the past two years of RACE scale experience. Among patients who underwent mechanical thrombectomy, 90% had one or more cortical signs. The presence of cortical signs in conjunction with the numerical value of the RACE score may serve as a strong predictor of treatment in the cath lab and serve as a basis for EMS triage to CSCs and early notification of the cath lab team.
—Brijesh P. Mehta, MD; Joy Sessa, RN, MSN; Randy S. Katz, DO, FACEP
II. Stroke VAN
Stroke VAN is an ELVO screening tool designed to be performed by providers in the emergency department or EMS personnel in the field. VAN requires you to assess for arm weakness and then test for other associated cortical symptoms that would suggest a larger area of the brain is involved. Stroke VAN is quite easy: Just have the patient hold both arms up for 10 seconds. If the patient has no weakness, then they are Stroke VAN-negative, and you’re done. If your patient has any arm weakness, then test for these cortical symptoms:
V—Vision
- Can the patient see on both left and right?
- Does the patient have crossed eyes?
A—Aphasia
- Does the patient speak and follow commands?
N—Neglect
- Does the patient have a forced gaze to one side?
- Can the patient track your fingers to the right and left?
- Can the patient feel both sides of their body at the same time?
If they have any one of these associated cortical symptoms and any arm weakness, then the patient is Stroke VAN-positive. Stroke VAN has some advantages over other clinical severity scales: 1) It doesn’t require the user to remember or add up numbers; 2) it picks up back-of-brain strokes by testing vision; and 3) it’s a mnemonic that reminds you what you need to assess the patient for (Figure 3).
Disadvantages of Stroke VAN are that its validation has been limited; it is presently used in only four states, and there is only one publication so far.9 We believe in Stroke VAN’s accuracy and believe first responders will find it easier to adopt than other clinical severity or ELVO recognition scales. For more information visit www.StrokeVAN.com and review some videos on how to perform the Stroke VAN assessment and its conception, application and implementation.
—Mohamed Teleb, MD; Mahesh V. Jayaraman, MD; Ryan A. McTaggart, MD
III. FAST-ED
The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale is a prehospital stroke scale based on components of the National Institutes of Health Stroke Scale (NIHSS), including facial weakness, arm weakness and speech changes (abnormal speech comprehension and/or production) as well as eye deviation and denial (e.g., neglect including asomatognosia and/or anosognosia). The FAST-ED scale has high predictive value for large-vessel occlusion strokes and has been shown to be comparable to the full NIHSS, but significantly less time-consuming and easier to use. The scale has a ternary distribution for the overall likelihood of ELVO (0–1, <15%; 2–3, ~30%; ≥4, ~60%–85%), which may result in better conformability to different patient scenarios compared to binary distribution scales.
The FAST-ED scale has potential advantages over other prehospital scales. In the Screening Technology and Outcomes Project in Stroke (STOP Stroke) study, 727 patients underwent CT angiography within the first 24 hours of stroke onset. One-third of the patients had ELVOs. Retrospective application of FAST-ED showed it had comparable accuracy to the full NIHSS in predicting ELVO, and higher accuracy than RACE and CPSS.10 Similarly, in another cohort that encompassed 1,085 patients (60.5% ELVO) who underwent CTA or MRA within six hours of stroke onset, FAST-ED had the top performance across several prehospital scales.11 These advantages likely derive from the fact that FAST-ED gives higher weights to items that are more predictive of cortical involvement and ELVO.
Finally, a smartphone app based on the FAST-ED scale is also available. It uses an elaborate decision-making algorithm that allows for a swift assessment of treatment options based on each patient’s characteristics and field transportation times from point of contact. This app is currently being applied and evaluated by many EMS services across the U.S. and abroad.
—Raul G. Nogueira, MD
IV. C-STAT
The Cincinnati Prehospital Stroke Scale, rebranded by the American Heart Association as FAST based on its components of facial droop, arm drift, speech abnormality and time since last known normal, was developed in the 1990s to screen for the presence of an acute stroke.12 If any of the three exam findings are present, the likelihood of the patient having a stroke is roughly 70%, and that likelihood increases with more abnormalities present. However, FAST does not differentiate severe from non-severe strokes.
The Cincinnati Stroke Triage Assessment Tool (C-STAT) was designed to further identify FAST-positive patients with a higher chance of ELVO that would benefit from triage to a hospital capable of endovascular care. The tool was derived and validated in known stroke patients, externally validated in another set of known stroke patients and prospectively validated by EMS providers in patients with an EMS impression of stroke.13–15 C-STAT performs comparably to other severity tools (e.g., RACE, LAMS, FAST-ED).
C-STAT is unique in a few ways. Focus groups of EMTs and paramedics translated the related NIHSS items into self-explanatory assessment questions. Each assessment item is a simple yes/no that doesn’t rely on subjective mild/moderate/severe determinations. Cincinnati Fire Department EMTs and paramedics participated in the prospective validation, done with no training; the assessment items were added as mandatory questions into the patient care reporting system and answered by the EMT/paramedic filling out the report.
Unlike other severity tools, C-STAT has been evaluated in identification of patients most likely to benefit from a comprehensive stroke center, as opposed to just identifying those with ELVO. Arguably, patients with intracranial or subarachnoid hemorrhage or severe ischemic stroke without ELVO may be better served at a hospital with on-site neurosurgery and dedicated neuroscience ICUs.
—Jason McMullan, MD
V. LAMS
The Los Angeles Motor Scale (LAMS) is a three-item, 0–5-point (per side) motor scale developed initially for prehospital use and validated in both prehospital and emergency department settings.16 Points are given for facial droop (1 if present), arm drift (1 if drift, 2 if arm falls rapidly or has no strength) and grip strength (1 for weak grip, 2 for no grip strength).
Recently the multicenter FAST-MAG trial provided convergent, divergent and predictive validation for the LAMS performed by paramedics in the field as an accurate general measure of a patient's stroke deficit severity.17 In addition, a LAMS score of 4 or higher has been validated as detecting patients whose strokes are likely due to emergency large-vessel occlusions. In a derivation study, a LAMS score of 4–5 predicted ELVO on arrival at CTA or MRA imaging with an overall sensitivity of 81% and specificity of 89%.16
Most recently, in a multi-ambulance, single-destination-hospital prospective validation study, the LAMS performed as well or better than seven other more complicated proposed prehospital ELVO-recognition instruments in identifying patients with ELVO on initial CTA or MRA.
The LAMS performed by paramedics in the field showed very good accuracy in identifying ELVO and CSC-appropriate patients.18 Approximately 25% of EMS-transported acute ischemic stroke patients will have a LAMS score of 4 or 5,17 and among these more than 70% will have an ELVO or bleed (be CSC-appropriate). While it is generally acknowledged that no scale (not even the NIHSS) can confidently exclude ELVO,19 it appears most typical presentations can be captured using the LAMS.
The LAMS is a nationally recommended tool for prehospital ELVO recognition and triage to comprehensive stroke centers and has been successfully implemented in several regions already.20
—Mahesh V. Jayaraman, MD; Jeff L. Saver, MD; Ryan A. McTaggart, MD
References
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2. Saver JL, Goyal M, Bonafe A, et al. Stent-retriever thrombectomy after intravenous t-PA vs. t-PA alone in stroke. N Engl J Med, 2015 Jun 11; 372(24): 2,285–95.
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11. Nogueira RG, Silva GS, Lima FO, et al. The FAST-ED App: A smartphone platform for the field triage of patients with stroke. Stroke, 2017 May; 48(5): 1,278–84.
12. Kothari RU, Pancioli A, Liu T, et al. Cincinnati Prehospital Stroke Scale: reproducibility and validity. Ann Emerg Med, 1999 Apr; 33(4): 373–8.
13. Katz BS, McMullan JT, Sucharew H, et al. Design and validation of a prehospital scale to predict stroke severity: Cincinnati Prehospital Stroke Severity Scale. Stroke, 2015 Jun; 46(6): 1,508–12.
14. Kummer BR, Gialdini G, Sevush JL, et al. External validation of the Cincinnati Prehospital Stroke Severity Scale. J Stroke Cerebrovasc Dis, 2016 May; 25(5): 1,270–4.
15. McMullan JT, Katz B, Broderick J, Schmit P, et al. Prospective prehospital evaluation of the Cincinnati Stroke Triage Assessment Tool. Prehosp Emerg Care, 2017 Jul–Aug; 21(4): 481–8.
16. Nazliel B, Starkman S, Liebeskind DS, et al. A brief prehospital stroke severity scale identifies ischemic stroke patients harboring persisting large arterial occlusions. Stroke, 2008 Aug; 39(8): 2,264–7.
17. Kim JT, Chung PW, Starkman S, et al. Field validation of the Los Angeles Motor Scale as a tool for paramedic assessment of stroke severity. Stroke, 2017 Feb; 48(2): 298–306.
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20. Jayaraman MV, Iqbal A, Silver B, et al. 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. J Neurointerv Surg, 2017 Mar; 9(3): 330–2.
Brijesh P. Mehta, MD, is a neurointerventional surgeon and director of stroke and neurocritical care for the Memorial Healthcare System in South Florida. He trained in neurology and endovascular neurosurgery at Massachusetts General Hospital, an affiliate of Harvard Medical School. He is interested in developing effective stroke systems of care with EMS integration aimed at providing lifesaving therapies that can achieve the best patient outcomes possible. Reach him at brmehta@mhs.net.
Joy Sessa, RN, MSN, graduated from Malone University in 1999 with a bachelor of science in nursing, completed her MSN at Walden University in 2007 and is now in the dissertation phase of her PhD in nursing at Florida Atlantic University. Over the last 18 years, she has practiced as a CVICU nurse and critical care educator. She is currently stroke program coordinator for Memorial Hospital West in Pembroke Pines, Fla. Reach her at jsessa@mhs.net.
Randy S. Katz, DO, FACEP, is chair of the Department of Emergency Medicine at Memorial Regional Hospital and medical director for the Department of Fire Rescue & Beach Safety for the city of Hollywood, Fla. He is a board-certified ED physician at one of the largest tertiary care centers in the southeast. Reach him at rkatz@mhs.net.
Mohamed Teleb, MD, is a neurointerventional surgery, stroke and neurocritical care physician at Banner Health in the Phoenix area. Reach him at mohamed.teleb@bannerhealth.com.
Mahesh V. Jayaraman MD, is director of interventional neuroradiology at the Warren Alpert School of Medicine at Brown University, where he also serves as an associate professor of diagnostic imaging, neurology and neurosurgery. He currently practices at Rhode Island Hospital. Reach him at mjayaraman@lifespan.org.
Ryan A. McTaggart, MD, is director of interventional neuroradiology at Rhode Island Hospital and an assistant professor of diagnostic imaging, neurology and neurosurgery at the Warren Alpert Medical School of Medicine at Brown University. He serves on the Standards and Guidelines Committee of the Society of Neurointerventional Surgery. Reach him at ryan.mctaggart@lifespan.org or on Twitter at @mobilestroke4U.
Raul G. Nogueira, MD, is an interventional neurologist and director of the Neuroendovascular Division at Grady Health’s Marcus Stroke and Neuroscience Center in Atlanta. Reach him at raul.g.nogueira@emory.edu.
Jason McMullan, MD, is an associate medical director for the Cincinnati Fire Department and oversees prehospital research at the University of Cincinnati’s Department of Emergency Medicine. He is part of the team developing and implementing the Cincinnati Stroke Triage Assessment Tool (C-STAT). Reach him at mcmulljo@ucmail.uc.edu.
Jeff L. Saver MD, is a professor of neurology at UCLA and director of the UCLA comprehensive stroke center. He was co-principal investigator for the National Institutes of Health FAST-MAG stroke trial, a multi-EMS agency, multihospital trial of ambulance-delivered brain-protective therapy for stroke. His research interests are in acute stroke treatment, stroke prevention, brain imaging and the cognitive consequences of stroke. Reach him at jsaver@mednet.ucla.edu.
