Abstract TP251: Pomona Large Vessel Occlusion Scale for Pre-hospital and Emergency Room Settings

Background: Early detection of acute stroke with large vessel occlusion (LVO) in both pre-hospital and emergency room settings results in favorable clinical outcomes. There is still no universal guideline for LVO screening. Method: We proposed that the presence of any of the following signs (Pomona scale): gaze deviation, expressive aphasia or neglect has a high sensitivity and accuracy to predict LVO. We reviewed a historical cohort of all acute stroke activation patients at Pomona Valley Hospital during February 2014 to January 2016. We tested Pomona scale in both groups. The predictive performance of Pomona scale was compared with different NIHSS cutoffs ( ≥4, ≥6, ≥8, ≥10), Los Angeles Motor Scale (LAMS), Cincinnati Prehospital Stroke Severity (CPSS) scale, Vision Aphasia and Neglect scale (VAN) and Prehospital Acute Stroke Severity (PASS) scale. Results: LVO was detected in 129 of the 777 acute stroke activation (17%). Two hundred and forty-two patients had nonLVO stroke (31%). NIHSS ≥4 and Pomona scale had highest sensitivity (0.99 and 0.98 respectively) to predict LVO. LAM scale had lowest sensitivity (0.68). Pomona scale had moderate accuracy (0.61) which was comparable with VAN (0.66) and PASS (0.67). NIHSS ≥4 had the least accuracy (0.28). When Pomona scale was combined with arm weakness, it had highest accuracy (0.77) and high sensitivity (0.92) to predict LVO in acute ischemic stroke subgroup. Using various NIHSS cut off to screen for LVO had lower accuracy than using other LVO screening tools. Conclusion: Pomona scale is very sensitive to predict LVO. It may be used as a screening tool for LVO in emergency room setting. Combination of arm weakness and Pomona scale may be used as a Pre-hospital LVO screening with moderately high accuracy.

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Abstract WP268: Evaluation and Validation of Prehospital Acute Stroke Severity Scale to Predict Large Vessel Occlusion in Patients with Proven Large Vessel Occlusion; Single Center Study in US

Stroke ◽

10.1161/str.48.suppl_1.wp268 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Muhammad H Niazi ◽

Mohammad El-Ghanem ◽

Alicia Richardson ◽

Kathy Morrison ◽

Reichwein Raymond ◽

...

Keyword(s):

Hospital Setting ◽

High Sensitivity ◽

Final Analysis ◽

Large Vessel ◽

P Value ◽

Stroke Severity ◽

Large Vessel Occlusion ◽

Anterior Circulation ◽

Vessel Occlusion ◽

Single Center Study

Background: In 2015 guidelines regarding endovascular treatment (ET) of Large Vessel Occlusion (LVO) in acute ischemic stroke (AIS) were changed, leading to more patients being transferred to comprehensive stroke centers (CSC) for ET in selected patients, sometimes bypassing primary stroke centers. In the era of ET, there is a need for a simple yet sensitive pre-hospital tool to triage appropriate patients to CSCs. Many prehospital stroke scales predicting LVO are not in widespread clinical use because they are complex and not reliable. A recently published Denmark study demonstrated the PASS tool (Score range 0-3) for detecting LVO where a score of ≥2 was considered to be optimal in predicting LVO with sensitivity of 0.66. Methods: A retrospective analysis of AIS patients with confirmed anterior circulation LVO by catheter-based cerebral angiography between January 2015 and June 2016 was conducted. PASS scores were calculated and correlated with NIHSS to assess for severity of the stroke. Results: Fifty-four patients received ET during the study period. Those who had posterior circulation LVO were excluded, leaving 44 patients for final analysis. Only 5 (11.4%) patients had PASS score of <2 while 39 patients (88.6 %) had a score of ≥2 showing sensitivity of 0.89 for those patients with LVO. Average NIHSS scores were 11 (95% CI 6.6-15) for PASS <2 and 20 (95% CI 18.5-22.5) for PASS ≥2 (p value 0.005). Conclusion: The PASS tool is simple, quick, and easy to perform and has high sensitivity in AIS patients with LVO. To assess its value and efficacy in real time it should be implemented into EMS systems and be performed in the pre-hospital setting.

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Retrospective Validation of Prehospital Acute Stroke Severity Scale to Predict Large Vessel Occlusion in Acute Stroke Patients - Single Center study in China

10.21203/rs.2.10860/v1 ◽

2019 ◽

Author(s):

Xiaoli Si ◽

Yuanjian Fang ◽

Wenqing Xia ◽

Tianwen Chen ◽

Huan Huang ◽

...

Keyword(s):

Acute Stroke ◽

Predictive Value ◽

Large Vessel ◽

Motor Deficits ◽

Stroke Severity ◽

Large Vessel Occlusion ◽

Anterior Circulation ◽

Vessel Occlusion ◽

Consciousness Disorder ◽

Gaze Palsy

Abstract Background and Purpose - To date, identifying emergent large vessel occlusion (ELVO) patients in the prehospital stage is important but still challenging. We aimed to retrospectively validate a simple prehospital stroke scale——Prehospital Acute Stroke Severity (PASS) scale to identify ELVO. Methods - We retrospectively evaluated our consecutive cohort of acute ischemic stroke (AIS) who underwent CT angiography (CTA), MR angiography (MRA) or digital subtraction angiography (DSA). PASS scale was calculated based on National Institutes of Health Stroke Scale (NIHSS) items retrospectively. The comparison of diagnostic parameters between PASS scale and NIHSS scale were performed. Results - Finally, a total of 605 patients were enrolled. ELVO patients with PASS≥2 had a median NIHSS score of 14. The best predictive value of PASS≥2 showed a similar predictive value compared with NIHSS≥9. Cortical symptoms such as consciousness disorder and gaze palsy were more specific indicators for ELVO than motor deficits. Consciousness disorder was more serious in posterior circulation infarct (PIC) while gaze palsy was more common in anterior circulation infarct (AIC). Conclusions - PASS scale had both good discrimination and calibration in our retrospective cohort. It could reflect acute stroke severity well and predict ELVO in an effective and simple way. Moreover, cortical symptoms had high specificities to predict ELVO on their own.

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Abstract TP82: Factors Associated With Good Collateral Flow in Acute Stroke Patients With Large Vessel Occlusion

Stroke ◽

10.1161/str.51.suppl_1.tp82 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Pierre Seners ◽

Pauline Roca ◽

Laurence Legrand ◽

Guillaume Turc ◽

Catherine Oppenheim ◽

...

Keyword(s):

Acute Stroke ◽

Large Vessel ◽

Stroke Severity ◽

Lesion Volume ◽

Dynamic Susceptibility ◽

Collateral Flow ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Factors Associated ◽

Tandem Occlusion

Introduction: Retrograde collateral flow is critical to maintain tissue perfusion despite large vessel occlusion. However, the premorbid factors associated with good collateral flow remain unclear, with substantial discrepancies in the literature. Methods: Patients from the registries of 6 French stroke centres with the following criteria were included: (1) acute stroke with isolated M1 occlusion ( i.e , without tandem occlusion) referred for thrombectomy between May 2015 and March 2017; and (2) baseline brain MRI, including diffusion weighted imaging, MR-angiography and dynamic susceptibility-contrast perfusion-weighted imaging (PWI). A collateral flow map derived from PWI source data was automatically generated, replicating Kim et al’s previously validated method (Ann. Neurol., 2014). Collateral flow was dichotomized into good and poor. The association between good collateral flow and baseline clinical, biological and radiological variables was studied. Results: One hundred and sixteen patients were included, of which 66 (57%) had good collaterals. As expected, the latter patients had lower admission NIHSS (median: 15 vs . 18, P=0.005) and lower baseline DWI lesion volume (median: 7ml vs . 32ml, P<0.001) than patient with poor collaterals. Onset-to-imaging delay and M1 occlusion site (proximal vs . distal) were similar in both groups (123min vs . 118min, P=0.75; 70% vs. 68%, P=0.85, respectively). There was no significant (P>0.05) difference in gender, age, history of hypertension or diabetes, current smoking, baseline blood glucose and use of statins or antiplatelets between the good and poor collaterals groups. Conclusions: Despite the expected association between PWI-derived collateral flow and baseline clinical and radiological stroke severity in our sample of acute M1 occlusions, there was no association with premorbid factors previously found associated in some -but not all- studies. Our findings suggest that collateral flow is predominantly explained by genetic factors.

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Abstract TP240: The PLUMBER (Prevalence of Large Vessel Occlusion Stroke in Mecklenburg County Emergency Response) Study

Stroke ◽

10.1161/str.48.suppl_1.tp240 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Adeline R Dozois ◽

Lorrie Hampton ◽

Carlene W Kingston ◽

Gwen Lambert ◽

Thomas J Porcelli ◽

...

Keyword(s):

Acute Stroke ◽

Emergency Response ◽

Predictive Value ◽

Large Vessel ◽

Stroke Severity ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Mecklenburg County ◽

Ischemic Attack ◽

Neurovascular Imaging

Introduction: Regional Emergency Medical System (EMS) protocols for acute stroke endorse routing patients with possible large vessel occlusion (LVO) acute ischemic strokes (AIS) directly to endovascular centers. These routing algorithms include prehospital stroke severity screens (PSSS) to determine the likelihood of an LVO AIS. An essential, but unreported, determinant of the predictive value of PSSS tools is the prevalence of LVO AIS stroke in the EMS population screened for stroke. Hypothesis: Among EMS patients transported to Mecklenburg county hospitals screened for stroke, acute LVO AIS prevalence ranges from 5-10%. Methods: We are conducting a prospective, observational study of all patients transported by the Mecklenburg county EMS agency who are either (1) dispatched as a possible stroke and/or (2) with a primary impression of stroke recorded by prehospital providers. We are reviewing medical records and neurovascular imaging studies to determine an acute LVO AIS diagnosis and the site(s) of occlusion. Results: Thus far, over a six-month period we have enrolled 1441 patients, of whom 33% (n=480) had a diagnosis consistent with acute stroke (ischemic stroke, hemorrhagic stroke, or transient ischemic attack), with 20% (n=287) being an AIS. Eighty-eight percent (n=253) of AIS patients underwent an intracranial CTA or MRA. The prevalence of LVO stroke in the EMS population enrolled was 5.7% (n= 82, 95% CI 4.6-7.0%), with the most common vessel occluded being M1 (n=46, 56% of LVO AIS). The prevalence of LVO AIS in patients dispatched as a possible stroke was 4.8% (n =56; 95% CI 3.6-6.1%), while the prevalence in patients with a primary impression of stroke was 10% (n=74; 95% CI 8.2-13%). Conclusions: Among patients screened for stroke by our county’s EMS agency, the prevalence of LVO AIS is low. This low LVO AIS prevalence, combined with a PSSS tool with modest accuracy, will yield poor predictive value for LVO AIS in an EMS population, resulting in a substantial rate of over-triage of non-LVO patients to endovascular centers. Data collection is ongoing to determine the accuracy of a prehospital stroke screen in identifying LVO AIS patients.

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Diagnostic value of transcranial ultrasonography for selecting subjects with large vessel occlusion: a systematic review

The Ultrasound Journal ◽

10.1186/s13089-019-0143-6 ◽

2019 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Daria Antipova ◽

Leila Eadie ◽

Ashish Stephen Macaden ◽

Philip Wilson

Keyword(s):

Systematic Review ◽

Diagnostic Accuracy ◽

Acute Stroke ◽

Clinical Assessment ◽

Assessment Tools ◽

Large Vessel ◽

Cochrane Library ◽

Direct Transfer ◽

Large Vessel Occlusion ◽

Vessel Occlusion

Abstract Introduction A number of pre-hospital clinical assessment tools have been developed to triage subjects with acute stroke due to large vessel occlusion (LVO) to a specialised endovascular centre, but their false negative rates remain high leading to inappropriate and costly emergency transfers. Transcranial ultrasonography may represent a valuable pre-hospital tool for selecting patients with LVO who could benefit from rapid transfer to a dedicated centre. Methods Diagnostic accuracy of transcranial ultrasonography in acute stroke was subjected to systematic review. Medline, Embase, PubMed, Scopus, and The Cochrane Library were searched. Published articles reporting diagnostic accuracy of transcranial ultrasonography in comparison to a reference imaging method were selected. Studies reporting estimates of diagnostic accuracy were included in the meta-analysis. Results Twenty-seven published articles were selected for the systematic review. Transcranial Doppler findings, such as absent or diminished blood flow signal in a major cerebral artery and asymmetry index ≥ 21% were shown to be suggestive of LVO. It demonstrated sensitivity ranging from 68 to 100% and specificity of 78–99% for detecting acute steno-occlusive lesions. Area under the receiver operating characteristics curve was 0.91. Transcranial ultrasonography can also detect haemorrhagic foci, however, its application is largely restricted by lesion location. Conclusions Transcranial ultrasonography might potentially be used for the selection of subjects with acute LVO, to help streamline patient care and allow direct transfer to specialised endovascular centres. It can also assist in detecting haemorrhagic lesions in some cases, however, its applicability here is largely restricted. Additional research should optimize the scanning technique. Further work is required to demonstrate whether this diagnostic approach, possibly combined with clinical assessment, could be used at the pre-hospital stage to justify direct transfer to a regional thrombectomy centre in suitable cases.

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Progression of cerebral infarction before and after thrombectomy is modified by prehospital pathways

Journal of NeuroInterventional Surgery ◽

10.1136/neurintsurg-2020-017155 ◽

2021 ◽

pp. neurintsurg-2020-017155

Author(s):

Alexander M Kollikowski ◽

Franziska Cattus ◽

Julia Haag ◽

Jörn Feick ◽

Alexander G März ◽

...

Keyword(s):

Patient Characteristics ◽

Large Vessel ◽

Stroke Severity ◽

Large Vessel Occlusion ◽

Time Intervals ◽

Vessel Occlusion ◽

Before And After ◽

Transferred Patients ◽

Stroke Center

BackgroundEvidence of the consequences of different prehospital pathways before mechanical thrombectomy (MT) in large vessel occlusion stroke is inconclusive. The aim of this study was to investigate the infarct extent and progression before and after MT in directly admitted (mothership) versus transferred (drip and ship) patients using the Alberta Stroke Program Early CT Score (ASPECTS).MethodsASPECTS of 535 consecutive large vessel occlusion stroke patients eligible for MT between 2015 to 2019 were retrospectively analyzed for differences in the extent of baseline, post-referral, and post-recanalization infarction between the mothership and drip and ship pathways. Time intervals and transport distances of both pathways were analyzed. Multiple linear regression was used to examine the association between infarct progression (baseline to post-recanalization ASPECTS decline), patient characteristics, and logistic key figures.ResultsASPECTS declined during transfer (9 (8–10) vs 7 (6-9), p<0.0001), resulting in lower ASPECTS at stroke center presentation (mothership 9 (7–10) vs drip and ship 7 (6–9), p<0.0001) and on follow-up imaging (mothership 7 (4–8) vs drip and ship 6 (3–7), p=0.001) compared with mothership patients. Infarct progression was significantly higher in transferred patients (points lost, mothership 2 (0–3) vs drip and ship 3 (2–6), p<0.0001). After multivariable adjustment, only interfacility transfer, preinterventional clinical stroke severity, the degree of angiographic recanalization, and the duration of the thrombectomy procedure remained predictors of infarct progression (R2=0.209, p<0.0001).ConclusionsInfarct progression and postinterventional infarct extent, as assessed by ASPECTS, varied between the drip and ship and mothership pathway, leading to more pronounced infarction in transferred patients. ASPECTS may serve as a radiological measure to monitor the benefit or harm of different prehospital pathways for MT.

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Abstract 1122‐000022: Delays in Care for Patients with Acute Stroke During Hospitalization for Other Reasons

Stroke: Vascular and Interventional Neurology ◽

10.1161/svin.01.suppl_1.000022 ◽

2021 ◽

Vol 1 (S1) ◽

Author(s):

Nicholas Vigilante ◽

Parth Patel ◽

Prasanth Romiyo ◽

Lauren Thau ◽

Mark Heslin ◽

...

Keyword(s):

Acute Stroke ◽

Acute Care ◽

Large Vessel ◽

Large Vessel Occlusion ◽

Single Center ◽

Anterior Circulation ◽

Vessel Occlusion ◽

Symptom Recognition ◽

Risk Patients ◽

Recognition Imaging

Introduction : In‐hospital stroke (IHS) is defined as stroke that occurs during hospitalization for non‐stroke conditions. We aimed to understand the timing of symptom recognition for patients who experienced IHS and its impact on the care they receive. Methods : A prospective, single center registry of adult patients (9/20/19‐2/28/21) was queried for acute anterior circulation IHS. Indications for hospitalization, delays from last known well (LKW) to symptom recognition, imaging, and treatment were explored. Results : Of 928 consecutively evaluated adults with acute stroke, 85 (9%) developed an anterior circulation IHS, 39 (46%) of whom were female, with a median age of 67 years (IQR 60–76) and median NIHSS of 15 (IQR 4–22). Sixty‐eight (80%) had a >1 hour delay from last known well to symptom recognition. Two patients (2%) received IV thrombolysis, although another 38 (45%) would have been eligible if not for a delay in symptom recognition. An ICA, M1, or M2 occlusion was observed in 18 patients (21%), 7 of whom were treated at a median of 174 minutes after LKW (IQR 65–219). Compared to the 11 patients who did not undergo thrombectomy with large vessel occlusion, those who underwent thrombectomy had non‐significantly shorter delays from LKW until neuroimaging (median 85 [IQR 65‐162] vs. 216 [IQR 133‐507], p = 0.12). Conclusions : While uncommon, patients with IHS experience delays in symptom recognition and treatment, which lead to exclusion from acute care treatment such as thrombolysis and thrombectomy. Earlier detection with more frequent nursing assessments or advanced neuromonitoring devices in at‐risk patients may reduce delays in care.

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Epidemiological Surveillance of the Impact of the COVID-19 Pandemic on Stroke Care Using Artificial Intelligence

Stroke ◽

10.1161/strokeaha.120.031960 ◽

2021 ◽

Author(s):

Raul G. Nogueira ◽

Jason M. Davies ◽

Rishi Gupta ◽

Ameer E. Hassan ◽

Thomas Devlin ◽

...

Keyword(s):

Artificial Intelligence ◽

Acute Stroke ◽

Systems Of Care ◽

Ct Perfusion ◽

Stroke Care ◽

Large Vessel ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Number Of Patients ◽

The Impact

Background and Purpose: The degree to which the coronavirus disease 2019 (COVID-19) pandemic has affected systems of care, in particular, those for time-sensitive conditions such as stroke, remains poorly quantified. We sought to evaluate the impact of COVID-19 in the overall screening for acute stroke utilizing a commercial clinical artificial intelligence platform. Methods: Data were derived from the Viz Platform, an artificial intelligence application designed to optimize the workflow of patients with acute stroke. Neuroimaging data on suspected patients with stroke across 97 hospitals in 20 US states were collected in real time and retrospectively analyzed with the number of patients undergoing imaging screening serving as a surrogate for the amount of stroke care. The main outcome measures were the number of computed tomography (CT) angiography, CT perfusion, large vessel occlusions (defined according to the automated software detection), and severe strokes on CT perfusion (defined as those with hypoperfusion volumes >70 mL) normalized as number of patients per day per hospital. Data from the prepandemic (November 4, 2019 to February 29, 2020) and pandemic (March 1 to May 10, 2020) periods were compared at national and state levels. Correlations were made between the inter-period changes in imaging screening, stroke hospitalizations, and thrombectomy procedures using state-specific sampling. Results: A total of 23 223 patients were included. The incidence of large vessel occlusion on CT angiography and severe strokes on CT perfusion were 11.2% (n=2602) and 14.7% (n=1229/8328), respectively. There were significant declines in the overall number of CT angiographies (−22.8%; 1.39–1.07 patients/day per hospital, P <0.001) and CT perfusion (−26.1%; 0.50–0.37 patients/day per hospital, P <0.001) as well as in the incidence of large vessel occlusion (−17.1%; 0.15–0.13 patients/day per hospital, P <0.001) and severe strokes on CT perfusion (−16.7%; 0.12–0.10 patients/day per hospital, P <0.005). The sampled cohort showed similar declines in the rates of large vessel occlusions versus thrombectomy (18.8% versus 19.5%, P =0.9) and comprehensive stroke center hospitalizations (18.8% versus 11.0%, P =0.4). Conclusions: A significant decline in stroke imaging screening has occurred during the COVID-19 pandemic. This analysis underscores the broader application of artificial intelligence neuroimaging platforms for the real-time monitoring of stroke systems of care.

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Pomona Large Vessel Occlusion Screening Tool for Prehospital and Emergency Room Settings

Interventional Neurology ◽

10.1159/000486515 ◽

2018 ◽

Vol 7 (3-4) ◽

pp. 196-203 ◽

Cited By ~ 2

Author(s):

Kessarin Panichpisal ◽

Kenneth Nugent ◽

Maharaj Singh ◽

Richard Rovin ◽

Reji Babygirija ◽

...

Keyword(s):

Los Angeles ◽

Acute Stroke ◽

Predictive Value ◽

Area Under The Curve ◽

Predictive Performance ◽

Large Vessel ◽

Stroke Severity ◽

Vessel Occlusion ◽

Comparable Accuracy ◽

Score Model

Background: Early identification of patients with acute ischemic strokes due to large vessel occlusions (LVO) is critical. We propose a simple risk score model to predict LVO. Method: The proposed scale (Pomona Scale) ranges from 0 to 3 and includes 3 items: gaze deviation, expressive aphasia, and neglect. We reviewed a cohort of all acute stroke activation patients between February 2014 and January 2016. The predictive performance of the Pomona Scale was determined and compared with several National Institutes of Health Stroke Scale (NIHSS) cutoffs (≥4, ≥6, ≥8, and ≥10), the Los Angeles Motor Scale (LAMS), the Cincinnati Prehospital Stroke Severity (CPSS) scale, the Vision Aphasia and Neglect Scale (VAN), and the Prehospital Acute Stroke Severity Scale (PASS). Results: LVO was detected in 94 of 776 acute stroke activations (12%). A Pomona Scale ≥2 had comparable accuracy to predict LVO as the VAN and CPSS scales and higher accuracy than Pomona Scale ≥1, LAMS, PASS, and NIHSS. A Pomona Scale ≥2 had an accuracy (area under the curve) of 0.79, a sensitivity of 0.86, a specificity of 0.70, a positive predictive value of 0.71, and a negative predictive value of 0.97 for the detection of LVO. We also found that the presence of either neglect or gaze deviation alone had comparable accuracy of 0.79 as Pomona Scale ≥2 to detect LVO. Conclusion: The Pomona Scale is a simple and accurate scale to predict LVO. In addition, the presence of either gaze deviation or neglect also suggests the possibility of LVO.

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Abstract TP237: Can We Improve Clinical Detection of Right Hemisphere Large Vessel Occlusion?

Stroke ◽

10.1161/str.51.suppl_1.tp237 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Sana Somani ◽

Melissa Gazi ◽

Michael Minor ◽

Joe Acker ◽

Abimbola Fadairo ◽

...

Keyword(s):

Left Hemisphere ◽

Right Hemisphere ◽

Trauma System ◽

Area Under The Curve ◽

Large Vessel ◽

Stroke Severity ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Emergency Medical ◽

The Right

Introduction: The Emergency Medical Stroke Assessment (EMSA) is a six point stroke severity scale with one point each for gaze preference, facial droop, arm drift, leg drift, abnormal naming, and abnormal repetition that was developed to help emergency medical services (EMS) providers identify acute ischemic stroke (AIS) patients with large vessel occlusion (LVO). We hypothesized that the EMSA would detect left hemisphere LVO with a higher sensitivity than right hemisphere LVO. Methods: We trained 24 trauma system-based emergency communication center (ECC) paramedics in the EMSA. ECC-guided EMS in performance of the EMSA on patients with suspected stroke. We compared the sensitivity, specificity, area under the curve (AUC), and 95% confidence interval (CI) of ECC-guided prehospital EMSA for right versus left hemisphere ICA or M1 occlusion. Results: We enrolled 569 patients from September 2016 through February 2018, out of which 236 had a discharge diagnosis of stroke and 173 had a diagnosis of AIS. We excluded patients with bilateral (n=21) and brainstem (n=21) AIS. There were 64 patients with left hemisphere AIS including 19 with LVO. There were 67 patients with right hemisphere AIS including 22 with LVO. A score of ≥ 4 points yielded a sensitivity of 84.2 (95% CI = 60.4-96.6) and specificity of 66.7 (51.1-80.0) for left hemisphere LVO compared to a sensitivity of 68.2 (45.1-86.1) and specificity of 73.9 (58.9-85.7) for right hemisphere LVO. For predicting a left hemisphere LVO, the AUC was 0.77 (0.65-0.90) compared to 0.66 (0.50-0.82) for right-sided LVO. Assigning 2 points for abnormal gaze yielded an AUC of 0.78 (0.66-0.91) versus 0.67 (0.52-0.83) for left and right hemisphere LVO, respectively. Conclusions: The EMSA, like the National Institutes of Health Stroke Scale (NIHSS) upon which it is based, is more sensitive to left compared to right hemisphere LVO. More heavily weighting abnormal gaze did not improve the sensitivity of the EMSA for right hemisphere LVO. There is no comparable data on the right versus left hemisphere performance of other prehospital scales. There is a need to develop sensitive tests of right hemisphere dysfunction that are suitable for use in the field.

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