bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1122‐000142: Safety and Efficacy of Surpass Streamline for Intracranial Aneurysms: A Multicenter US Real‐World Experience (SESSIA)
Authors: Vivanco‐Suarez Juan , Mendez‐Ruiz Alan , Mudassir Farooqui , Zevallos Cynthia B , Galecio‐Castillo Milagros , Bekelis Kimon , Singer Justin A , Altschul David J , Fifi Johanna , Al‐Mufti Fawaz , Gross Bradley , Jankowitz Brian , Kan Peter T , Rabinovich Rita , Newman Sarah , Orru Emanuele , Wakhloo Ajay , Ortega‐Gutierrez Santiago
Published: December 2021

Introduction
: Flow diversion has established itself as standard treatment of wide complex intracranial aneurysms (IA). Its recognition has been validated with positive occlusion rates and favorable clinical outcomes. The Surpass Streamline (SS) flow diverter (FD) is a braided cobalt/chromium alloy implant with 72 or 96 wires approved by the FDA in 2018. The aim of this study is to determine the safety and efficacy of the SS in a post‐marketing large US cohort.

Methods
: We performed a multicenter, retrospective study for consecutive patients treated with the SS FD for IA between January 2018 and June 2021 in the United States. Inclusion criteria for participants were: 1. Adults (≥ 18 years) and 2. Treatment with SS FD for IA. Primary safety end point was a major ipsilateral stroke (increase in National Institutes of Health Stroke Scale Score of ≥ 4) or neurological death within 12 months. Primary efficacy was assessed using the 3‐point Raymond‐Roy (RR) occlusion scale on digital subtraction angiography (DSA) at 6‐12‐month follow‐up.

Results
: A total of 276 patients with 313 aneurysms were enrolled. The median age was 59 years and 199 (72%) were females. The most common comorbidities included hypertension in 156 (57%) subjects followed by hyperlipidemia in 76 (28%) patients. One hundred and twenty‐two (44%) patients were asymptomatic while subarachnoid hemorrhage was present in only 10 (4%) patients. A total of 143 (46%) aneurysms were left‐sided. Aneurysms were located as follows: 274 (88%) were in the anterior circulation with paraophthalmic being the most common in 120 (38%) followed by petrocavernous ICA in 81 (26%); 33 (11%) aneurysms were located in the posterior circulation with basilar trunk being the most common in 14 (5%). The mean maximum aneurysm dome width was 5.77 ± 4.7 mm, neck width 4.22 ± 3.8 mm and dome to neck ratio was 1.63 ± 1.3 mm. The mean number of SS FD implanted per aneurysm was 1.06 (range 1–3) with more than one SS FD implanted in 21 (7%) aneurysms. Modified Rankin Scale (mRS) of 0–2 was present in 206/213 (97%) patients at 6–12 month follow‐up. The complete aneurysm occlusion (RR 1) rate was 145/175 (83%) among subjects who had angiographic follow‐up at 6–12 months. Major stroke and death was encountered in 7 (2%) and 5 (1.8%) of the patients respectively.

Conclusions
: Our data represent the largest real‐world study using SS FD. These results corroborate its post‐marketing safety and efficacy for the treatment of intracranial aneurysms showing more favorable rates to the initial experience during SCENT trial.
Abstract 1122‐000144: Experiences and Strategies Developing an Evidence‐Based Clinical Guideline for Ischemic Stroke in a Middle‐income Setting
Authors: Sequeiros Joel M , Alva‐Diaz Carlos , Pacheco‐Rios Kevin , Nieto‐Gutierrez Wendy , Ortega‐Gutierrez Santiago
Published: December 2021

Introduction
: Developing an evidence‐based clinical practice guideline in a middle‐income country is challenging. After a discussion with the stakeholders, we identified and prioritized the need for a clinical guideline about ischemic stroke in our country. We defined stakeholders to anyone who has an interest in the recommendations of the guideline, including patients' representatives, practitioners, policy/decision makers, commissioners of guidelines and other end users.

Methods
: We developed an evidence‐based guideline using the Grades of Recommendation, Assessment, Development, and Evaluation System (GRADE) approach with a multidisciplinary team including independent methodologists, local and international clinical experts. Systematic step‐by‐step search strategy was used. Four clinical guidelines were identified, quality of development of these guidelines was evaluated using the Appraisal of Guidelines for Research & Evaluation (AGREE II) tool. In the absence of a systematic review in the guideline to answer the clinical question, we proceeded to search for primary studies. The certainty of evidence was classified according to the GRADE system, as high, moderate, low, and very low. Recommendations were classified according to strength, as strong or conditional, and to direction, as in favor or against. Applicability and acceptability were evaluated by the stakeholders and patient’s representatives. External validation by national and international experts in the field was performed.

Results
: Eight clinical questions related to diagnosis, management, and early rehabilitation for ischemic stroke were formulated. Evidence from systematic reviews and meta‐analysis for every clinical question was discussed, an update was made when needed, and finally, twenty‐eight trustworthy recommendations (8 strong and 20 conditional) were developed. Also, thirty‐eight good practice points and two flowcharts were developed.

Conclusions
: In a setting with limited resources a high‐quality clinical guideline could be developed using good quality data from the systematic reviews found in previous guidelines. The GRADE approach could be very useful to contextualize the available evidence, making the process feasible and efficient.
Abstract 1122‐000163: Stroke Center Accessibility Study in the U.S. Using Geospatial Analysis and Machine Learning
Authors: Ali Ahsan , Edgell Randall
Published: December 2021

Introduction
: Background: Several accrediting bodies certify the level of stroke care hospitals provide. The Joint Commission on Hospital Accreditation (JC) is the largest accrediting body in the United States. There is no open source Geographic Information Systems (GIS) dataset showing the distribution of JC accredited centers by ZIP code. Objective: to create a stroke center accessibility and stroke center desert system using geospatial analysis and machine learning which provides real‐time assessment of stroke center availability, distribution and access to care.

Methods
: Geospatial data layers of JC accredited stroke centers were compiled using data sources including U.S. Census Bureau and CDC. Map layers corresponding to the levels of JC accredited stroke hospitals geolocated using ZIP code were created as follows: 1) Acute Stroke Ready 2) Primary 3) Thrombectomy Capable 4) Comprehensive Stroke Center. A GIS dataset displaying stroke mortality by region was obtained from the ArcGIS Living Atlas. Stroke center deserts are analyzed using a 4.5 hour drive map along with population and diversity. Machine learning models were implemented to estimate stroke mortality as a function of distance to care centers and capability levels of the stroke centers.

Results
: Stroke centers are highly concentrated within large urban centers. There are geographic regions that have poor access to stroke centers. Such regions include the Gulf Coast States of Louisiana, Mississippi, and Alabama that have large areas with poor stroke center access while having some of the highest stroke mortality in the country. (Figure 1 ‐ Stroke Center Distribution in the United States) Dot Symbols: Blue = Acute Stroke Ready; Green = Primary; Yellow = Thrombectomy Capable; Red = Comprehensive Raster Data: Stroke Mortality by ZIP Code; White to Purple Scale with Purple = Highest Mortality

Conclusions
: There are regional variations in stroke center availability. There are certain regions with high stroke mortality with very little stroke center access. Geospatial AI tools can be utilized to improve stroke systems of care.
Abstract 1122‐000165: Endovascular Intervention for a Thrombotic Adverse Event During Andexanet Alfa Infusion
Authors: Kayyali Mohammad N , Dumitrascu Oana M
Published: December 2021

Introduction
: Andexanet alfa is the only specific reversal agent for factor Xa inhibitors and received FDA approval in 2018. Here we report an early infusion adverse event in a patient with acute intraventricular hemorrhage (IVH) that received Andexanet alfa, with an unfavorable outcome.

Methods
: A 73‐year‐old male presented to our emergency department (ED) after he developed sudden onset of severe headache without other associated neurological symptoms. An outpatient brain MRI showed IVH, that remained stable in size (2.4 cm3) on a follow‐up head CT performed in our ED. CT angiogram showed a 60% stenosis of the left supraclinoid internal carotid artery. The patient was taking apixaban 5 mg twice daily for atrial fibrillation (last dose 5.5 hours prior to presentation).

Results
: The anticoagulation was reversed with Andexanet alfa, 400 mg bolus given at 18:30, followed by 480 mg infusion over 2 hours started at 19:00 (12 hours from last apixaban dose). At 19:00, he developed left middle cerebral artery (MCA) ischemic stroke symptoms (global aphasia) that resolved with head‐of‐the‐bed flattening. CT perfusion demonstrated left ICA territory mismatch (342 ml) and 76 ml core. Shortly after CT perfusion, the patient developed a persistent complete left MCA stroke syndrome with NIH stroke scale (NIHSS) score 23. Decision was made to perform emergent cerebral angiogram which demonstrated a large, fresh thrombus in the left cervical ICA. Thrombectomy was successful with TICI score 2B. Patient’s neurological status initially improved. However, despite this intervention, patient developed a large territory infarct. As neurologic status remained poor, family withdrew care and patient died.

Conclusions
: ANNEXA‐A and ANNEXA‐R were parallel trials of Andexanet alfa for factor Xa inhibitor reversal that demonstrated a transient increase in prothrombotic factors post Andexanet alfa infusion. Neither of these phase 3 trials nor the previous phase 2 trials reported a clinical thrombotic event very early during the infusion. The ANNEXA‐4 trial (Phase 3) enrolled subjects with active major bleeding on a factor Xa inhibitor and 10% developed a thrombotic event during the 30‐day follow‐up period. 41% of the thrombotic complications were acute ischemic stroke (AIS), 35% (5 patients) experienced an AIS in the first six days post‐administration and the earliest reported thrombotic event occurred day 1 post infusion. Our case report illustrates an early cerebrovascular thrombotic event with dismal outcome despite timely and effective mechanical reperfusion therapy, which could be due to vessel re‐obstruction in setting of a hypercoagulable state. We aim to make vascular neurologists, neurointensivists and neurosurgeons aware of this possible occurrence when reversing patients with factor Xa‐related intracranial hemorrhages.
Abstract 1122‐000184: Cerebral Arterial Variations in Patients with Ischemic Stroke Undergoing Mechanical Thrombectomy
Authors: Solewski Bernard , Brzegowy Karolina , Brzegowy Paweł , Musiał Agata , Popiela Tadeusz , Walocha Jerzy A
Published: December 2021

Introduction
: This study aimed to determine what anatomical variants of the Circle of Willis (CoW) and the middle cerebral artery(MCA) are observed in patients with acute M1 occlusion and whether their prevalence differs from that described as “normal” in anatomy textbooks.

Methods
: We have performed a retrospective assessment of radiological examinations of patients with stroke due to middle cerebral artery M1 segment occlusion. All patients underwent mechanical thrombectomy from January 2015 until March 2021. The anatomy of the CoW was assessed on initial CT‐angiography and DSA. Branches of the MCA were observed on control DSA after recanalization.

Results
: A total of 100 patients were included in the analysis (58 females and 42 males, mean age: 71.6 +/‐ 13.9). Fully complete CoW was observed in 19% of patients. A total of 10% of patients had an incomplete anterior portion of CoW. In the incomplete anterior portion subgroup, the most common variation was the absence of anterior communicating artery (6% of total hemispheres), followed by the absence of one A1 (3% of total hemispheres). An incomplete posterior portion of CoW was identified in 79% of the patients. The absence of posterior communicating artery (PCoA) was observed in 59 patients. Sixteen patients had adult‐type PCoA, 3 patients had transitional‐type PCoA and 21 patients had fetal‐type posterior cerebral artery (PCA). In the subgroup of patients with fetal‐type posterior circle, 5 patients had no P1 segment of PCA. Anterior temporal branch of MCA was observed in 45% of the patients. Middle cerebral artery bifurcation was found in 80% of hemispheres, and trifurcation in 20%. In the bifurcation subgroup, 26% of MCAs had a dominating upper branch and 18% had a dominating lower branch. A duplicate MCA was observed in one hemisphere.

Conclusions
: In comparison to normal anatomy described in anatomy textbooks, the population of patients suffering from ischemic stroke due to M1 occlusion had a lower proportion of complete and closed CoW. A foetal type PCoA was observed to be prevalent (21%) in patients suffering from acute M1 occlusion. Detailed anatomical knowledge of anatomical variants of CoW in patients undergoing mechanical thrombectomy is essential for clinicians performing intravascular interventions and may aid procedure planning.
Abstract 1122‐000188: 3D Analysis of Atherosclerotic Plaque Enhancement and the Parent Vessel
Authors: Sanchez Sebastian , Raghuram Ashrita , Miller Alberto Varon , Fakih Rami , Samaniego Edgar A
Published: December 2021

Introduction
: High resolution vessel wall imaging (HR‐VWI) is a promising tool in studying intracerebral atherosclerotic disease. The analysis of the interplay between the patterns of enhancement between the plaque and its parent vessel can generate further insights on the biology of these lesions. We have developed a 3D method of plaque and parent vessel analysis.

Methods
: Images from fifty‐five plaques were obtained using 7T HR‐VWI. T1 and T1+Gd sequences were performed. 3D reconstructions of the plaque and its parent vessel were generated with 3D Slicer. Using an in‐house code, probes were orthogonally extended from the lumen of the vessel into the vessel wall and the plaque. Signal intensity values were then normalized to the corpus callosum. 3D heat maps and histograms were generated from hundreds of data points. A detailed analysis of the morphology of the histograms was performed to determine the uptake of gadolinium (Gd) by the parent vessel and the plaque. Variations in the width of the histogram were measured with the standard deviation.

Results
: Forty‐one patients with 55 plaques (41 culprit and 15 non culprit) were included. There was no difference in enhancement in T1‐pre between culprit and non‐culprit plaques when compared to the parent vessel (width = 0.14 ± 0.05 and 0.14 ± 0.03, respectively; p = 0.91). On the T1+Gd culprit plaques were significantly more enhancing compared to the parent vessel (0.26 ± 0.10) than non‐culprit plaques (0.20 ± 0.06) (p = 0.02). The presence of an enhancing plaque creates a bimodal distribution that increases the width of the histogram curve (figure).

Conclusions
: Culprit plaques exhibit different patterns of enhancement relative to the parent vessel compared to non‐culprit plaques. Histogram analysis of the parent vessel and its plaques provides a new set of metrics that may be used as a biomarker of disease progression.
Abstract 1122‐000207: Mechanical Thrombectomy of the Fetal Posterior Cerebral Artery
Authors: Abdalkader Mohamad , Abdalkader Mohamad , Sahoo Anurag , Dmytriw Adam A , Brinjikji Waleed , Dabus Guilherme , Raz Eytan , Renieri Leonardo , Laiso Antonio , Maud Alberto , Martinez‐Galdamez Mario , Galvan‐Fernandez Jorge , Arteaga Miguel Schuller , Al‐Mufti Fawaz , Amuluru Krishna , Fifi Johanna T , Majidi Shahram , Khandelwal Priyank , Moore Justin , Kiley Nicole , Ortega‐Gutierrez Santiago , Hassan Ameer E , Siegler James E , Nagel Simon , Zaidat Osama O , Nguyen Thanh N
Published: December 2021

Introduction
: Fetal posterior cerebral artery (FPCA) occlusion is a rare but potentially disabling cause of stroke. While endovascular treatment is established for acute large vessel occlusion (LVO) stroke, FPCA occlusions were excluded from acute ischemic stroke trials. We aim to report the feasibility, safety and outcome of mechanical thrombectomy (MT) in acute FPCA occlusions.

Methods
: We performed a multi‐center retrospective review of consecutive patients who underwent MT of acute FPCA occlusion. Primary FPCA occlusion was defined as an occlusion that was identified on the pre‐procedure CT angiogram or baseline angiogram whereas a secondary FPCA occlusion was defined as an occlusion that occurred secondary to embolization to a new territory after recanalization of a different LVO. Demographics, clinical presentation, imaging findings, endovascular treatment and outcome were reviewed.

Results
: There were twenty‐five patients with acute FPCA occlusion who underwent MT, distributed across 14 centers. Median NIHSS on presentation was 16. There were 76% (19/25) of patients who presented with primary FPCA occlusion and 24% (6/25) of patients who had a secondary FPCA occlusion. The configuration of the FPCA was full in 64% patients and partial or “fetal‐type” in 36% of patients. FPCA occlusion was missed on initial CTA in 21% of patients with primary FPCA occlusion (4/19). The site of occlusion was posterior communicating artery in 52%, P2 segment in 40% and P3 in 8% of patients. TICI 2b/3 reperfusion was achieved in 96% of FPCA patients. There were no intra‐procedural complications. At 90 days, 48% (12/25) were functionally independent as defined by mRS≤2.

Conclusions
: Endovascular treatment of acute FPCA occlusion is safe and technically feasible. A high index of suspicion is important to detect occlusion of the fetal posterior cerebral artery in patients presenting with anterior circulation stroke syndrome and patent anterior circulation.
Abstract 1122‐000218: Flow Reversal After Stent Diversion Causes In‐Stent Thrombosis and Anemia‐Driven Ischemia
Authors: Blanden Adam R , Philip Karan , Masoud Hesham E
Published: December 2021

Introduction
: Large symptomatic ICA aneurysms are rare, but present a life threatening risk of rupture that increases with size, female sex, and age >50 at the time of diagnosis, among other risk factors. Historically, large carotid aneurysms have been treated with intentional carotid sacrifice, requiring recruitment of contralateral, posterior, and ECA‐supplied collaterals to provide flow to the anterior circulation previously supplied by the sacrificed ICA, lest the patient experience an iatrogenic stroke. While still a viable option in some cases, flow diverting stents provide an attractive alternative to vessel sacrifice. By providing a channel for blood to bypass the aneurysm, the stent can effectively exclude the aneurism from active circulation while preserving a path for blood to travel to the anterior cerebral circulation it currently provides.

Methods
: Here, we present a case of a 1.3 cm symptomatic left cavernous ICA aneurysm treated with such a flow diverting stent.

Results
: The patient presented to the emergency department with left sided ptosis. CTA head and neck revealed the 1.3 cm left sided cavernous ICA aneurysm. She was treated endovascularly under general anesthesia with continuous intra‐operative monitoring. The procedure was complicated by iatrogenic flow reversal through the Circle of Willis at the time of stent deployment and resultant in situ thrombosis of the stent without alteration in electrical signals recorded at the scalp – thus creating a de facto carotid sacrifice without intra‐operative complication. Follow up doppler study revealed a loss of flow through the left ICA and reversal of flow through the ophthalmic artery on the left side, thus confirming ECA collateral supply to the area. Post‐op course was complicated by extensive bleeding from the scalp electrode sites used for intraoperative monitoring due to hyper‐response to aspirin‐ticagrelor dual‐antiplatelet therapy. This gave rise to a symptomatic anemia that manifested as pressure‐dependent left‐sided circulatory failure on exam – specifically hemiparesis and aphasia. The symptoms ultimately resolved with pressure augmentation, blood transfusion, and supportive care in the Neuro ICU. The patient was successfully transitioned to a general neurology floor with subsequent resolution of the anemia and, correspondingly, the symptoms.

Conclusions
: The patient was discharged to rehab and at 4‐month follow‐up is again living independently with no residual deficits. This case has significance for pre‐operative anti‐platelet optimization for flow diverting stents, management of post‐operative complications of flow‐diverting stent placement including thrombosis and bleeding, and optimal critical care support for patients with pressure‐dependent ischemia. Specifically, the course of the patient’s symptoms and anemia raise the question of optimal hemoglobin targets in the subset of patients with pressure‐dependent ischemia, and how to best reach those targets.
Abstract 1122‐000237: Prior Vascular Risk Factors Affecting Presentation Time and Utilization of Acute Ischemic Stroke Therapies
Authors: Charles Jude H , Zamora Mario P , Yavagal Dileep R
Published: December 2021

Introduction
: Multiple factors have been reported to influence the time between onset of symptoms in acute ischemic stroke and hospital presentation. Although education level is one independent factor in presentation, as we previously reported, health literacy has not been fully assessed regarding specific patient knowledge on stroke or its known risk factors. This study aims to determine whether having a history of vascular risk factors such as prior stroke, coronary artery disease (CAD), or atrial fibrillation (AF) influence presentation time and acute ischemic stroke therapy utilization.

Methods
: This study included 250 acute ischemic stroke patients presenting to a large academic community hospital from February to December 2018. Educational level was defined within four categories: Grade School, High School, College or Higher, and Unknown. Last seen normal, symptom onset, and arrival times were acquired. Vascular risk factors chosen for this study included prior stroke, CAD, and AF. History of vascular risk factors was verified by medical documentation showing prior diagnosis by physician. Initial NIH Stroke Scale score, stroke location, vessel involved, LDL, hemoglobin A1c, gender, and race were also obtained. Patients were categorized based on their level of education, the presence or absence of vascular risk factors, and utilization of tPA or thrombectomy (MT). The primary outcomes were onset‐to‐arrival time (OTA), in minutes, and utilization rates of acute ischemic stroke therapies (either tPA, MT, or both). Subgroup analysis was conducted to associate education level with each vascular risk factor, comparing OTA and acute ischemic stroke therapy utilization rate.

Results
: As previously reported, educational level was inversely associated with OTA and positively associated with utilization of at least one acute ischemic stroke therapy. Prior stroke, CAD, and AF showed a substantial OTA decrease for all education groups except for College. Prior stroke decreased OTA in Grade School by 24% (764 vs. 579); High School by 30% (222 vs. 154) and College by 20% (52 vs. 41). CAD decreased OTA in Grade School by 65% (734 vs. 253), High School by 14% (209 vs. 180), and College by 3% (50 vs 49). AF decreased OTA in Grade School by 88% (764 vs. 91) and High School by 56% (216 vs. 95), but increased in College by 35% (47 vs. 64). History of prior stroke decreased utilization of both tPA and MT by 14%; CAD increased tPA use by 8% and MT by 5%; while AF increased tPA use by 9% and MT by 12%.

Conclusions
: Having at least one prior vascular risk factor (prior stroke, CAD, AF), diagnosed by a physician, was associated with lower OTA in Grade School and High School educated patients. A history of prior stroke was associated with lower acute stroke therapy utilization (tpa and MT), while both CAD and AF were associated with increased acute stroke therapy utilization.
Abstract 1122‐000239: Understanding The Gap in Public Stroke Awareness in India’s Younger Generation
Authors: Deshpande Preetal
Published: December 2021

Introduction
: Stroke is one of the major leading causes of death and disability in India. One reason is the lack of stroke awareness in India. With the adoption of an unhealthy lifestyle like a lack of physical exercise, smoking, and excessive alcohol consumption, newer stroke cases are more prevalent in young adults. I surveyed about 100 high school students from urban cities in India to assess their stroke knowledge and decide how to take measures to bring more awareness about its symptoms, risk factors, and new effective treatments.

Methods
: I randomly selected high school students(9th‐12th graders) from Uttarakhand, Uttar Pradesh, Madhya Pradesh, Maharashtra, and Karnataka states to participate in the survey I created. I distributed multiple‐choice anonymous questionnaires to hundreds of high school students. The participants completed survey questions to the best of their ability. The survey assessed candidates' demographic characteristics, knowledge of stroke symptoms, stroke risk factors, ability to identify stroke symptoms, and knowledge about stroke‐related surgeries. It is important to note that these surveys were primarily sent to high school students in urban areas, where the knowledge and resources are relatively better than the rural areas.

Results
: I received a total of 91 survey responses from high schoolers across different states in India (30% were from Madhya Pradesh, 40% were from Maharashtra and 30% were from Karnataka and Uttar Pradesh). Even though 53.8% of the respondents reported some level of prior knowledge about the stroke, the rest of the respondents simply did not know or had misconceptions about stroke. Nearly ¾ did not know any stroke risk factors, warning signs, or recognize that the brain gets affected during the stroke. Only 27.5% of the students have heard of the popular acronym BE FAST(Balance Eyes Face Arms Speech Time) which is used to detect stroke in a patient. It is shocking that only 12.1% of the respondents have received an education on stroke at least once in their lifetime.

Conclusions
: The high schoolers have a good recognition of some basic facts of stroke. However, they have a poor understanding of stroke risk factors, the severity of the disease, and the treatment availability. However, there is hope. More than 57% of the high schoolers in my survey mentioned that they were willing to learn about stroke and ways to prevent and detect it. So it is our duty to educate the younger generation about the dangers of stroke and how to prevent, as well as to detect it. We should strive to provide access to these children in the hope of helping spread awareness all around India one step at a time.
Mild Luminal Stenosis of Parent Artery and Neurologic Deterioration After Acute Lacunar Stroke
Authors: Yang Dixon , Gutierrez Jose , Cutting Shawna , Raz Eytan , Gurel Kursat , Torres Jose , Mac Grory Brian , Scher Erica , Pirooz Sahnaz , Havenon Adam de , Ishida Koto , Furie Karen , Elkind Mitchell S.V. , Yaghi Shadi
Published: December 2021

Background

Early neurologic deterioration (END) occurs in a quarter of acute lacunar infarcts, but the underlying pathophysiological features are poorly understood. We sought to determine the association between luminal stenosis (<50%) of the parent artery and END.

Methods

This observational study included consecutive patients with lacunar stroke from the ischemic stroke registries of New York University Langone Health and Brown University. All included patients were admitted for acute lacunar stroke, which was defined as a subcortical infarct <1.5 cm on computed tomography or <2 cm on diffusion‐weighted imaging without significant stenosis (>50%) in the parent vessel and no cardioembolic source. We defined END as any neurologic deterioration referable to the acute lacunar stroke and not related to a medical or noncerebrovascular neurological complication. We used univariate and logistic regression analyses to determine associations between luminal stenosis (<50%) and the odds of END. Furthermore, we attempted to validate findings using the Columbia University Medical Center stroke registry and perform a meta‐analysis combining the derivation and validation groups because of the expected small samples and event rates.

Results

The New York University Langone Health and Brown University sample included 205 patients, of whom 41 (20%) had END. In adjusted models, we found no definite association between luminal stenosis (<50%) and END (adjusted odds ratio [OR], 1.74; 95% CI, 0.73–4.14). From Columbia University Medical Center, 361 total patients were included, of whom 59 (16%) had END. In adjusted models, we found an association between luminal stenosis (<50%) and END (adjusted OR, 2.28; 95% CI, 1.15–4.50). Meta‐analysis of both cohorts found luminal stenosis (<50%) associated with END (relative risk, 1.69; 95% CI, 1.17–2.43).

Conclusions

In this multicenter study, luminal stenosis (<50%) may be associated with END following an acute lacunar infarct. Larger studies using vessel wall imaging are needed to validate our findings.
To Augment or Not to Augment? A Comparative Study on Text Augmentation Techniques for Low-Resource NLP
Authors: Şahin Gözde Gül
Published: December 2021

Data-hungry deep neural networks have established themselves as the de facto standard for many NLP tasks, including the traditional sequence tagging ones. Despite their state-of-the-art performance on high-resource languages, they still fall behind their statistical counterparts in low-resource scenarios. One methodology to counterattack this problem is text augmentation, that is, generating new synthetic training data points from existing data. Although NLP has recently witnessed several new textual augmentation techniques, the field still lacks a systematic performance analysis on a diverse set of languages and sequence tagging tasks. To fill this gap, we investigate three categories of text augmentation methodologies that perform changes on the syntax (e.g., cropping sub-sentences), token (e.g., random word insertion), and character (e.g., character swapping) levels. We systematically compare the methods on part-of-speech tagging, dependency parsing, and semantic role labeling for a diverse set of language families using various models, including the architectures that rely on pretrained multilingual contextualized language models such as mBERT. Augmentation most significantly improves dependency parsing, followed by part-of-speech tagging and semantic role labeling. We find the experimented techniques to be effective on morphologically rich languages in general rather than analytic languages such as Vietnamese. Our results suggest that the augmentation techniques can further improve over strong baselines based on mBERT, especially for dependency parsing. We identify the character-level methods as the most consistent performers, while synonym replacement and syntactic augmenters provide inconsistent improvements. Finally, we discuss that the results most heavily depend on the task, language pair (e.g., syntactic-level techniques mostly benefit higher-level tasks and morphologically richer languages), and model type (e.g., token-level augmentation provides significant improvements for BPE, while character-level ones give generally higher scores for char and mBERT based models).
Improved N-Best Extraction with an Evaluation on Language Data
Authors: Björklund Johanna , Drewes Frank , Jonsson Anna
Published: December 2021

We show that a previously proposed algorithm for the N-best trees problem can be made more efficient by changing how it arranges and explores the search space. Given an integer N and a weighted tree automaton (wta) M over the tropical semiring, the algorithm computes N trees of minimal weight with respect to M. Compared with the original algorithm, the modifications increase the laziness of the evaluation strategy, which makes the new algorithm asymptotically more efficient than its predecessor. The algorithm is implemented in the software Betty, and compared to the state-of-the-art algorithm for extracting the N best runs, implemented in the software toolkit Tiburon. The data sets used in the experiments are wtas resulting from real-world natural language processing tasks, as well as artificially created wtas with varying degrees of nondeterminism. We find that Betty outperforms Tiburon on all tested data sets with respect to running time, while Tiburon seems to be the more memory-efficient choice.
Anatomy of the Beginning of the Housing Boom across U.S. Metropolitan Areas
Authors: Ferreira Fernando , Gyourko Joseph
Published: December 2021

We provide novel estimates of the location, timing, magnitude, and determinants of the start of the previous U.S. housing boom. The housing cycle cannot be interpreted as a single, national event, as different markets began to boom across a decade-long period, some of them multiple times. A fundamental factor, income of prospective buyers, can account for half of the initial jump in price growth, while expansion of purchases by underrepresented minorities cannot. The start of the boom also was financed conventionally, not by subprime mortgages. The latter's share did rise sharply over time, but only after a multiyear lag.
Trade-offs? The Impact of WTO Accession on Intimate Partner Violence in Cambodia
Authors: Erten Bilge , Keskin Pinar
Published: December 2021

We study the impact of trade-induced changes in labor market conditions on violence within the household. We exploit the local labor demand shocks generated by Cambodia’s WTO accession to assess how changes in the employment of women relative to men affected the risk of intimate partner violence. We document that men in districts facing larger tariff reductions experienced a significant decline in paid employment, whereas women in harder-hit districts increased their entry into the labor force. These changes in employment patterns triggered backlash effects by increasing intimate partner violence, without changes in marriage, fertility, psychological distress, or household consumption.
Do Academically Struggling Students Benefit from Continued Student Loan Access? Evidence from University and Beyond
Authors: Chu Yu-Wei Luke , Cuffe Harold E.
Published: December 2021

We estimate the effects of student loan access on educational attainment and labor market returns in New Zealand. We exploit the introduction of a national policy mandating a 50% pass rate for student loan renewals using a regression discontinuity design. Retaining loan access increases reenrollment for students around the threshold, and a majority eventually graduate with a bachelor's degree within seven years. We find that retaining student loan access leads to large labor market returns for struggling students. The additional debt from further borrowing is small relative to the earnings returns and declines quickly due to faster repayment.
National Human Rights Institutions and Access to Justice for National Minorities in Europe
Authors: Tudisco Vincenzo
Published: December 2021

This article focuses on the role that National Human Rights Institutions play in guaranteeing access to justice for national minorities. Based on the osce hcnm Graz Recommendations on Access to Justice and National Minorities, this study aims at identifying commons issues and good practices by comparing rules and practices concerning minority representation in nhris, nhris’ focus on national minority issues, and nhris’ role in providing access to justice for national minorities. Separate subsections cover collective-groups’ complaints and the relevance of groups during investigations; regional offices; and websites, languages, and online complaints. The conclusion highlights that protecting access to justice for national minorities entails both more ‘focus’ and ‘access’. More focus should be guaranteed by relevant legislation and nhris’ annual reports through separate chapters or sections on minorities. More access includes minority representation in nhris, regional offices, groups’ complaints, multilingual and easy-to-access websites, as well as online tools for complaints.
The Limited Role of the European Union in the Management and Governance of the COVID-19 Pandemic
Authors: Grogan Joelle
Published: December 2021

Building on two global Symposia hosted by the Verfassungsblog and convened by the author, the 2020 “COVID-19 and States of Emergency” and the 2021 “Power and the COVID-19 Pandemic”, in addition to the findings of the Democracy Reporting International ‘Rule of Law Stress Test’ which surveyed EU Member States’ responses to the pandemic, this article investigates the impact of the pandemic on governance and legal systems within the EU, and evaluates the actions taken by EU institutions and national governments in response to the health crisis against the standards of the rule of law.
Identifying Major Actors of Shi’i Revival in Post-Soviet Azerbaijan
Authors: Goyushov Altay , Rovshanoglu Kanan
Published: December 2021

This article is an attempt to describe, analyze, and evaluate the major players who contributed to the rise of transnational Shi’i activism in post-Soviet Azerbaijan. The article is based on a chronology of the most important events, and internet resources, personal contacts, observations, and interviews have been the primary source of this research.
Georgian Israelites or Jews of Georgia
Authors: Kakitelashvili Ketevan
Published: December 2021

The paper explores the evolution of Georgian-Jewish identity in different political, ideological, and cultural contexts from the late nineteenth to the early twenty-first centuries. It is focused on the beginning of the twentieth century when religious and national dimensions of Georgian-Jewish identity were developed as competing identity models. This paper addresses the impact of these identity models on contemporary Georgian-Jewish identity.
Hygrophorus aurantiosquamosus (Hygrophoraceae, Agaricales), a new species of Hygrophorus section Chrysodontes from western China
Authors: HUANG HONG-YAN , ZHANG WEN-HAO , HUANG TING , TANG LI-PING
Published: December 2021

In China, the European species, Hygrophorus chrysodon, is widely reported in western and northeastern provinces. After carefully comparing H. chrysodon from China and Europe, we found that the European and Chinese materials were different lineages in molecular trees, and there were also obvious differences in morphology between the two lineages. The evidence from morphology and phylogeny indicated that the presence of H. chrysodon in China is doubtful and that the Chinese material represents an undescribed species. Thus, H. aurantiosquamosus is proposed as a new species. This new taxon is characterized by its yellowish white pileus covered with golden yellow squamules, a stipe concolorous with the pileus and covered with yellow floccules, a distinct pileipellis composed of narrow hyphae with inflated terminal elements of various shapes (clavate, cylindrical, lacrymoid to subglobose), and elongate to subcylindrical basidiospores measuring 9.5–12 × 4–5.5 μm. The new species occurs in Picea forests at high elevations of western China, such as Qinghai, Sichuan, and Tibet provinces.
Rapid Change in Surface-Based Temperature Inversions across the World during the Last Three Decades
Authors: Zeng Huiyu , Tian Pengfei , Zhang Min , Cao Xianjie , Liang Jiening , Zhang Lei
Published: December 2021

Surface-based inversions (SBIs) are significant and common natural phenomena in the planetary boundary layer, and they play essential roles in weather and climate. This study used radiosonde data from 493 radiosonde stations worldwide from the Integrated Global Radiosonde Archive during 1989–2019 to investigate the variations in surface-based inversions from a global perspective. The results indicated that, from 1989 to 2019, the SBI frequency increased and the SBI strength variations with fluctuations and SBI depth decreased over the study period. However, the spatial distribution of frequency, strength, and depth did not have consistent trends. In comparison with the Southern Hemisphere, SBIs in the Northern Hemisphere occurred more frequently and were stronger and deeper. In terms of stations over land and the ocean, we found that the SBI frequency over the ocean has increased faster than that over land in the past 15 years and that the SBI strength over land was almost 2 times that of the ocean. The amplitudes of the annual cycle of SBI characteristics over land were greater than over the ocean in both hemispheres, and the frequency, strength, and depth were greater over land. This study investigated surface-based inversions from a global perspective and filled a gap in the current research on SBIs.
Linking Equatorial African Precipitation to Kelvin Wave Processes in the CP4-Africa Convection-Permitting Regional Climate Simulation
Authors: Ayesiga Godwin , Holloway Christopher E. , Williams Charles J. R. , Yang Gui-Ying , Stratton Rachel , Roberts Malcolm
Published: December 2021

Observational studies have shown the link between convectively coupled Kelvin waves (CCKWs) and eastward-propagating rainfall anomalies. We explore the mechanisms in which CCKWs modulate the propagation of precipitation from west to east over equatorial Africa. We examine a multiyear state-of-the-art Africa-wide climate simulation from a convection-permitting model (CP4A) along with a parameterized global driving-model simulation (G25) and evaluate both against observations (TRMM) and ERA-Interim (ERA-I), with a focus on precipitation and Kelvin wave activity. We show that the two important related processes through which CCKWs influence the propagation of convection and precipitation from west to east across equatorial Africa are 1) low-level westerly wind anomalies that lead to increased low-level convergence, and 2) westerly moisture flux anomalies that amplify the lower- to midtropospheric specific humidity. We identify Kelvin wave activity using zonal wind and geopotential height. Using lagged composite analysis, we show that modeled precipitation over equatorial Africa can capture the eastward-propagating precipitation signal that is associated with CCKWs. Composite analysis on strong (high-amplitude) CCKWs shows that both CP4A and G25 capture the connection between the eastward-propagating precipitation anomalies and CCKWs. In comparison to TRMM, however, the precipitation signal is weaker in G25, while CP4A has a more realistic signal. Results show that both CP4A and G25 generally simulate the key horizontal structure of CCKWs, with anomalous low-level westerlies in phase with positive precipitation anomalies. These findings suggest that for operational forecasting, it is important to monitor the day-to-day Kelvin wave activity across equatorial Africa.
Large-Scale Environments of Successive Atmospheric River Events Leading to Compound Precipitation Extremes in California
Authors: Fish Meredith A. , Done James M. , Swain Daniel L. , Wilson Anna M. , Michaelis Allison C. , Gibson Peter B. , Ralph F. Martin
Published: December 2021

Successive atmospheric river (AR) events—known as AR families—can result in prolonged and elevated hydrological impacts relative to single ARs due to the lack of recovery time between periods of precipitation. Despite the outsized societal impacts that often stem from AR families, the large-scale environments and mechanisms associated with these compound events remain poorly understood. In this work, a new reanalysis-based 39-yr catalog of 248 AR family events affecting California between 1981 and 2019 is introduced. Nearly all (94%) of the interannual variability in AR frequency is driven by AR family versus single events. Usingk-means clustering on the 500-hPa geopotential height field, six distinct clusters of large-scale patterns associated with AR families are identified. Two clusters are of particular interest due to their strong relationship with phases of El Niño–Southern Oscillation (ENSO). One of these clusters is characterized by a strong ridge in the Bering Sea and Rossby wave propagation, most frequently occurs during La Niña and neutral ENSO years, and is associated with the highest cluster-average precipitation across California. The other cluster, characterized by a zonal elongation of lower geopotential heights across the Pacific basin and an extended North Pacific jet, most frequently occurs during El Niño years and is associated with lower cluster-average precipitation across California but with a longer duration. In contrast, single AR events do not show obvious clustering of spatial patterns. This difference suggests that the potential predictability of AR families may be enhanced relative to single AR events, especially on subseasonal to seasonal time scales.
Interaction between Upper-Ocean Submesoscale Currents and Convective Turbulence
Authors: Verma Vicky , Pham Hieu T. , Sarkar Sutanu
Published: December 2021

The interaction between upper-ocean submesoscale fronts evolving with coherent features, such as vortex filaments and eddies, and convective turbulence generated by surface cooling of varying magnitude is investigated. Here, we decompose the flow into finescale (FS) and submesoscale (SMS) fields explicitly to investigate the energy pathways and the strong interaction between them. Most of the surface cooling flux is transferred to the FS kinetic energy through the FS buoyancy flux carried by the convective plumes. Overall, the SMS strengthens due to surface cooling. The frontogenetic tendency at the submesoscale increases, which counters the enhanced horizontal diffusion by convection-induced turbulence. Downwelling/upwelling strengthens, and the peak SMS vertical buoyancy flux increases as surface cooling is increased. Furthermore, the production of FS energy by SMS velocity gradients (the interscale transfer term, which mediates forward energy cascade) is significant, up to half of the production by convection. Examination of potential vorticity reveals that surface cooling promotes higher levels of secondary symmetric instability (SI), which coexists with the persistent baroclinic instability. The forward interscale transfer is found to increase in the regions with SI.
Endothelial Dysfunction and Endocan Levels in Patients with Gilbert Syndrome and Moderate Hyperbilirubinemia
Authors: Zengin Oguzhan , Sahiner Enes Seyda , Inan Osman , Topcuoglu Canan , Turhan Turan , Altiparmak Emin , Yilmaz Nisbet , Ates Ihsan
Published: December 2021

In this study, we aim to evaluate the presence of endothelial dysfunction in Gilbert syndrome patients with left ventricular mass index (LVMI) and endocan levels. The study included 60 patients who diagnosed with Gilbert syndrome and 60 healthy controls who did not have any known diseases. Human endocan levels were measured using a sandwich ELISA method. The endocan and LVMI levels were lower in the Gilbert syndrome group than in the healthy controls. In the Gilbert syndrome group, total bilirubin level was negatively correlated with LVMI (r = −0246; P = .007) and endocan levels (r = −.270; P = .046). In the Gilbert syndrome group, increasing age (β ± SE = 20.78 ± 7.47; P = .006), was a positive independent predictor of LVMI, and increasing high-density lipoprotein cholesterol (HDL-C) (β ± SE = −.27 ± .09; P = .007), and total bilirubin levels (β ± SE = −6.09 ± 3.02; P = .046) were found to be a negative independent predictor. These results support that endothelial dysfunction is decreased in Gilbert Syndrome patients with mild hyperbilirubinemia compared with the healthy control group.