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Background: Posterior reversible encephalopathy syndrome (PRES) can cause short-term cerebrovascular complications, such as brain infarction and hemorrhage. We hypothesized that PRES is also associated with an increased long-term risk of stroke. Methods: We performed a retrospective cohort study in the United States using statewide all-payer claims data from 2016 to 2018 on all admissions to nonfederal hospitals in 11 states. Adults with PRES were compared with adults with renal colic (negative control) and transient ischemic attack (TIA; positive control). Any stroke and the secondary outcomes of ischemic and hemorrhagic stroke were ascertained using International Classification of Diseases, Tenth Revision, Clinical Modification codes . We excluded prevalent stroke. We used time-to-event statistics to calculate incidence rates and Cox proportional hazards analyses to evaluate the association between PRES and stroke, adjusting for demographics and stroke risk factors. In a sensitivity analysis, outcomes within 2 weeks of index admission were excluded. Results: We identified 1606 patients with PRES, 1192 with renal colic, and 38 216 with TIA. Patients with PRES had a mean age of 56±17 years; 72% were women. Over a median follow-up of 0.9 years, the stroke incidence per 100 person-years was 6.1 (95% CI, 5.0–7.4) after PRES, 1.0 (95% CI, 0.62–1.8) after renal colic, and 9.7 (95% CI, 9.4–10.0) after TIA. After statistical adjustment for patient characteristics and risk factors, patients with PRES had an elevated risk of stroke compared with renal colic (hazard ratio [HR], 2.3 [95% CI, 1.7–3.0]), but lower risk than patients with TIA (HR, 0.67 [95% CI, 0.54–0.82]). In secondary analyses, compared with TIA, PRES was associated with hemorrhagic stroke (HR, 2.0 [95% CI, 1.4–2.9]). PRES was associated with ischemic stroke when compared with renal colic (HR, 1.9 [95% CI, 1.4–2.7]) but not when compared with TIA (HR, 0.49 [95% CI, 0.38–0.63]). Results were similar with 2-week washout. Conclusions: Patients with PRES had an elevated risk of incident stroke.

Background: In patients with intracerebral hemorrhage (ICH), it is unclear whether early neurological deterioration, hematoma expansion (HE), and outcome vary by supratentorial ICH location (deep versus lobar). Herein, we assessed these relationships in a clinical trial cohort that underwent brain imaging early after symptom onset. We hypothesized that HE would occur more frequently, and outcome would be worse in patients with deep ICH. Methods: We performed a post hoc analysis of the FAST (Factor-VII-for-Acute-Hemorrhagic-Stroke-Treatment) trial including all patients with supratentorial hemorrhage. Enrolled patients underwent brain imaging within 3 hours of symptom onset and 24 hours after randomization. Multivariable regression was used to test the association between ICH location and 3 outcomes: HE (increase of ≥33% or 6mL), early neurological deterioration (decrease in Glasgow Coma Scale score ≥2 points or increase in National Institutes of Health Stroke Scale ≥4 points within 24 hours of admission), and 90-day outcome (modified Rankin Scale). Results: Of 841 FAST trial patients, we included 728 (mean age 64 years, 38% women) with supratentorial hemorrhages (deep n=623, lobar n=105). HE (44 versus 27%, P =0.001) and early neurological deterioration (31 versus 17%, P =0.001) were more common in lobar hemorrhages. Deep hemorrhages were smaller than lobar hemorrhages at baseline (12 versus 35mL, P P P =0.03). However, when adjusting for variables included in the ICH score including ICH volume, deep location was associated with worse and lobar location with better outcome (odds ratio lobar location, 0.58 [95% CI, 0.38–0.89]; P =0.01). Conclusions: In this secondary analysis of randomized trial patients, lobar ICH location was associated with larger ICH volume, more HE and early neurological deterioration, and worse outcome than deep ICH. After adjustment for prognostic variables, however, deep ICH was associated with worse outcome, likely due to their proximity to eloquent brain structures.

Background: Continued smoking after stroke is associated with a high risk of stroke recurrence and other cardiovascular disease. We sought to comprehensively understand the epidemiology of smoking cessation in stroke survivors in the United States. Furthermore, we compared smoking cessation in stroke and cancer survivors because cancer is another smoking-related condition in which smoking cessation is prioritized. Methods: We performed a cross-sectional analysis of data from the Centers for Disease Control and Prevention Behavioral Risk Factor Surveillance System, an annual, nationally representative health survey. Using pooled data from 2013 to 2019, we identified stroke and cancer survivors with a history of smoking. We used survey procedures to estimate frequencies and summarize quit ratios with attention to demographic and geographic (state-wise and rural-urban) factors for stroke survivors. The quit ratio is conventionally defined as the proportion of ever smokers who have quit. Then, we used multivariable logistic regression to compare quit ratios in stroke and cancer survivors while adjusting for demographics and smoking-related comorbidities. Results: Among 4 434 604 Americans with a history of stroke and smoking, the median age was 68 years (interquartile range, 59–76), and 45.4% were women. The overall quit ratio was 60.8% (95% CI, 60.1%–61.6%). Quit ratios varied by age group, sex, race and ethnicity, and several geographic factors. There was marked geographic variation in quit ratios, ranging from 48.3% in Kentucky to 71.5% in California. Furthermore, compared with cancer survivors, stroke survivors were less likely to have quit smoking (odds ratio, 0.72 [95% CI, 0.67–0.79]) after accounting for differences in demographics and smoking-related comorbidities. Conclusions: There were considerable demographic and geographic disparities in smoking quit ratios in stroke survivors, who were less likely to have quit smoking than cancer survivors. A targeted initiative is needed to improve smoking cessation for stroke survivors.

Background: Administrative data can be useful for stroke research but have historically lacked data on stroke severity. Hospitals increasingly report the National Institutes of Health Stroke Scale (NIHSS) score using an International Classification of Diseases , Tenth Revision ( ICD-10 ) diagnosis code, but this code’s validity remains unclear. Methods: We examined the concordance of ICD-10 NIHSS scores versus NIHSS scores recorded in CAESAR (Cornell Acute Stroke Academic Registry). We included all patients with acute ischemic stroke from October 1, 2015, when US hospitals transitioned to ICD-10 , through 2018, the latest year in our registry. The NIHSS score (range, 0–42) recorded in our registry served as the reference gold standard. ICD-10 NIHSS scores were derived from hospital discharge diagnosis code R29.7xx, with the latter 2 digits representing the NIHSS score. Multiple logistic regression was used to explore factors associated with availability of ICD-10 NIHSS scores. We used ANOVA to examine the proportion of variation ( R 2 ) in the true (registry) NIHSS score that was explained by the ICD-10 NIHSS score. Results: Among 1357 patients, 395 (29.1%) had an ICD-10 NIHSS score recorded. This proportion increased from 0% in 2015 to 46.5% in 2018. In a logistic regression model, only higher registry NIHSS score (odds ratio per point, 1.05 [95% CI, 1.03–1.07]) and cardioembolic stroke (odds ratio, 1.4 [95% CI, 1.0–2.0]) were associated with availability of the ICD-10 NIHSS score. In an ANOVA model, the ICD-10 NIHSS score explained almost all the variation in the registry NIHSS score ( R 2 =0.88). Fewer than 10% of patients had a large discordance (≥4 points) between their ICD-10 and registry NIHSS scores. Conclusions: When present, ICD-10 codes representing NIHSS scores had excellent agreement with NIHSS scores recorded in our stroke registry. However, ICD-10 NIHSS scores were often missing, especially in less severe strokes, limiting the reliability of these codes for risk adjustment.

Introduction: While well-established risk factors for cervical artery dissection include trauma and connective tissue disorders, many cases are considered “spontaneous.” Although the incidence of cervical artery dissection is greatest in the young, the prevalence increases with age, suggesting a potential role of vascular disease. In this study, we hypothesized that atherosclerosis may be a risk factor for cervical artery dissection. Methods: We performed a retrospective cohort study using administrative claims data from a 5% sample of Medicare beneficiaries between 2008 and 2018. The exposures of interest were vascular risk factors potentially associated with atherosclerosis including coronary artery disease, hyperlipidemia, hypertension, diabetes mellitus, heart failure, chronic kidney disease, chronic obstructive pulmonary disease, valvular heart disease, atrial fibrillation, tobacco use, and alcohol abuse. The primary outcome was a new diagnosis of cervical artery dissection. Marginal structural Cox models were used to characterize the association between the exposures and outcomes, adjusted for time-dependent confounding, age, sex, race/ethnicity, and prior stroke. Results: Among 2,256,826 eligible Medicare beneficiaries, 1,527 (0.07%) developed cervical artery dissection, with a mean age of 70.8, compared to 71.5 in those without cervical artery dissection. The following exposures were found to be significantly associated with the development of cervical artery dissection: coronary artery disease (1.81 [1.63-2.01]), hyperlipidemia (1.84 [1.61-2.11]), hypertension (2.04 [1.76-2.37]), diabetes mellitus (1.34 [1.21-1.49]), heart failure (1.44 [1.25-1.67]), chronic kidney disease (1.38 [1.20-1.59]), chronic obstructive pulmonary disease (1.3 [1.16-1.46]), valvular heart disease (1.81 [1.60-2.04]), atrial fibrillation (HR 1.75 [95% CI 1.54-1.98]), tobacco use (1.84 [1.57-2.15]), and alcohol abuse (1.84 [1.56-2.16]). Conclusion: In a large population-based cohort of older people, atherosclerotic risk factors were associated with subsequent cervical artery dissection. Further studies exploring the role of atherosclerosis in the development of cervical artery dissection are required.

Introduction: Anticoagulation in patients with acute intracranial hemorrhage (ICH) and mechanical heart valves (MHV) is often held to mitigate the risk of ICH expansion or recurrence; however there exists a competing risk of acute ischemic stroke (AIS). Optimal timing to resume anticoagulation after ICH remains uncertain. Methods: We retrospectively studied ICH patients with MHV at two academic hospitals from April, 2000-August, 2018. The primary outcome was a composite endpoint of symptomatic hematoma expansion or new ICH, AIS, and intracardiac thrombus up to 30 days post-ICH. The exposure was timing of re-initiation of anticoagulation classified as early if therapeutic anticoagulation was resumed up to 7 days after ICH; late if ≥7 and up to 30 days after ICH; and never if not resumed or resumed after 30-days post-ICH. Cox proportional hazard models were built adjusted for age, sex, and covariates significantly different in univariate analysis at a pre-specified p-value threshold of 0.05. Results: We identified 184 patients with ICH and MHV (65 anticoagulated early, 100 resumed late, 19 not resumed by day 30 post-ICH). We observed 12 AIS, 16 new ICH, and 6 intracardiac thromboses. The mean time from ICH to anticoagulation in the cohort was 12.7 days. Patients resumed early versus late were more likely to have atrial fibrillation (62% versus 42%), and less likely to be reversed (75% versus 94%), to undergo hematoma evacuation (23% versus 43%), have midline shift (27% versus 52.9%), and to have intracerebral involvement (26% versus 49%). There was no significant difference in the hazard of AIS, new or symptomatic ICH expansion, or the composite outcome among those resumed early versus late. Patients not resumed within 30 days post-ICH had a significantly higher risk of AIS compared to those resumed within 30 days (HR 15.9; 95% C.I.1.9-129.7, p=0.0098). Discussion: In this study of ICH patients with MHV, there was no difference in the 30-day thrombotic and hemorrhagic brain-related outcomes in patients anticoagulated within 7 days versus 7-30 days. Withholding anticoagulation within the first 30 days was associated with a significantly higher risk of AIS. Our findings provide a discrete time window to guide resumption of anticoagulation in MHV patients with ICH.

Background: Intracerebral hemorrhage (ICH) is associated with an increased risk of ischemic stroke. Whether there are racial and ethnic disparities in the risk of ischemic stroke after ICH is poorly understood. Hypothesis: Non-Hispanic Black and Hispanic ICH patients have a higher risk of ischemic stroke compared to White ICH patients. Methods: We retrospectively analyzed data from the Healthcare Cost and Utilization Project on all hospitalizations at all nonfederal hospitals in Florida from 2005 to 2018 and New York from 2006 to 2016. We included patients with an ICH, and without a prior or concomitant diagnosis of ischemic stroke. ICH and ischemic stroke were ascertained using validated ICD-9-CM and ICD-10-CM codes. Using Cox proportional hazard models, we studied the relationship between race and risk of ischemic stroke, after adjustment of demographics and comorbidities. Results: We included 55,582 patients with ICH- 66% Non-Hispanic White, 19% Non-Hispanic Black, and 13% Hispanic. Black and Hispanic patients were younger and had a higher prevalence of cardiovascular comorbidities; however, atrial fibrillation was more prevalent among White patients. During a median follow up period of 3.6 years (IQR 0.7-7.2), an incident ischemic stroke occurred in 3,361 (9%) Non-Hispanic White, 1,308 (12%) Non-Hispanic Black, and 858 (12%) Hispanic patients (p Conclusions: Among patients with ICH, Non-Hispanic Black and Hispanic patients had a significantly higher risk of ischemic stroke compared to Non-Hispanic White patients.

Introduction: Serum neutrophil-lymphocyte ratio (NLR) is a surrogate marker for the inflammatory response after intracerebral hemorrhage (ICH), and is associated with perihematomal edema and long-term functional outcomes. Whether NLR is associated with short-term ICH complications is poorly understood. Hypothesis: NLR is associated with 30-day infection and thrombotic events after ICH. Methods: We performed a post hoc exploratory analysis of the Clot Lysis: Evaluating Accelerated Resolution of Intraventricular Hemorrhage (CLEAR) III trial. The study exposure was the serum NLR obtained at baseline, and on days 3 and 5. The co-primary outcomes, ascertained at 30 days, were any infection and a thrombotic event, defined as composite of cerebral infarction, myocardial infarction, or venous thromboembolism; both infection and thrombotic event were determined via adjudicated adverse event reporting. Binary logistic regression was used to study the relationship between NLR and outcomes, after adjustment for demographics, ICH severity and location, and treatment randomization. Results: Among the 500 patients enrolled in CLEAR III, we included 228 (45.6%) with no missing data on daily NLR in the first week. There were no differences in demographics, comorbidities, or ICH severity between patients with and without data on NLR. In adjusted logistic regression models, NLR at day 3 was associated with infection (OR, 1.2; 95% CI, 1.01-1.26), but not with thrombotic events (OR, 0.96; 95% CI, 0.85-1.10). Conversely, NLR at day 5 was associated with thrombotic events (OR, 1.2, 95% CI, 1.01-1.26), but not with infections (OR, 1.03; 95% CI, 0.94-1.14). NLR at baseline was not associated with either outcome. Conclusions: Serum NLR ascertained between days 3 and 5 was associated with 30-day infection and thrombotic events after ICH, suggesting that NLR could be a potential early biomarker for ICH-related complications.

Introduction: Chronic hypertension is an established long-term risk factor for stroke. However, little is known about short-term stroke risk after an episode of acute severe hypertension without evidence of target organ damage (i.e., hypertensive urgency [HU]). We evaluated the short-term risk of stroke after an ED visit with HU resulting in discharge home (treat-and-release). Methods: We performed a case-crossover study using deidentified administrative claims from all nonfederal EDs and hospitals across 11 states. The study cohort comprised patients diagnosed with any stroke (ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage), defined using validated ICD-10 codes, between 2016-2018. We tabulated and compared incident ED visits for HU during case periods (2-week intervals from 0-24 weeks before the index stroke) to control periods (equivalent time periods exactly 1 year earlier). ED visits with HU were ascertained using the ICD-10 code I16.0, which we validated through detailed chart review of 50 patients at our center resulting in a code sensitivity and specificity of 100% and 96%, respectively. We used McNemar’s test for matched data to calculate risk ratios (RRs) for an ED HU visit occurring before stroke. Results: Among 45,063 patients with stroke, 22,417 (50%) were female and 37,577 (83%) had a prior diagnosis of hypertension. There were 201 patients with stroke who had at least one ED visit for HU during the preceding 24 weeks. An ED visit for HU was significantly more common in the 2 weeks before stroke compared to the 2-week control period 1 year earlier (RR, 5.1; 95% CI, 2.4-12.7; p Conclusion: Treat-and-release ED visits for HU are associated with a significantly increased short-term risk of stroke.

Introduction: Syndromes of cerebrovascular dysregulation such as posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS) can be challenging to diagnose given their rarity and the need for advanced neuroimaging to diagnose them. We sought to measure the rate of potential PRES/RCVS misdiagnosis in the ED and identify features associated with misdiagnosis. Methods: We conducted a retrospective cohort study of patients with PRES/RCVS using deidentified administrative claims data from all nonfederal EDs and hospitals across 11 states from 2016-2018. To identify patients with PRES/RCVS, we used the previously validated ICD-10-CM codes I67.841 and I67.83. We defined patients with a probable misdiagnosis of PRES/RCVS as those with an ED visit resulting in discharge to home that occurred within the 14 days prior to their PRES/RCVS hospitalization. Only preceding ED visits where a non-specific neurological condition (e.g., headache, dizziness, numbness) was diagnosed were considered instances of probable ED misdiagnosis. Standard tests of comparison between patients with versus without probable misdiagnosis were used to identify patient-level and ED facility-level features associated with misdiagnosis. Results: We identified 4,633 patients hospitalized for PRES/RCVS; the majority (4,169; 90.0%) had PRES. A total of 210 patients (4.5%, 95% CI: 3.95-5.17) had at least one preceding ED visit with a probable misdiagnosis; these patients were younger (mean age 47.7 vs. 53.8 years; P Conclusion: Probable ED misdiagnosis occurred in nearly 1 of 20 cases of PRES/RCVS in a large, multistate cohort.

The risk of stroke and cerebrovascular disease complicating infection with SARS-CoV-2 has been extensively reported since the onset of the pandemic. The striking efforts of many scientists in cooperation with regulators and governments worldwide have rapidly brought the development of a large landscape of vaccines against SARS-CoV-2. The novel DNA and mRNA vaccines have offered great flexibility in terms of antigen production and led to an unprecedented rapidity in effective and safe vaccine production. However, as mass vaccination has progressed, rare but catastrophic cases of thrombosis have occurred in association with thrombocytopenia and antibodies against PF4 (platelet factor 4). This catastrophic syndrome has been named vaccine-induced immune thrombotic thrombocytopenia. Rarely, ischemic stroke can be the symptom onset of vaccine-induced immune thrombotic thrombocytopenia or can complicate the course of the disease. In this review, we provide an overview of stroke and cerebrovascular disease as a complication of the SARS-CoV-2 infection and outline the main clinical and radiological characteristics of cerebrovascular complications of vaccinations, with a focus on vaccine-induced immune thrombotic thrombocytopenia. Based on the available data from the literature and from our experience, we propose a therapeutic protocol to manage this challenging condition. Finally, we highlight the overlapping pathophysiologic mechanisms of SARS-CoV-2 infection and vaccination leading to thrombosis.

To describe a comprehensive review of the epidemiology, pathophysiology, and treatment of stroke in the era of COVID-19.COVID-19 is associated with myriad neurological disorders, including cerebrovascular disease. While ischemic stroke is the most common, COVID-19 is associated with an increased risk of intracranial hemorrhage, arterial dissection, posterior reversible encephalopathy syndrome, and cerebral venous sinus thrombosis. In this review, we discuss the epidemiology, pathophysiology, and treatment of stroke due to COVID-19. In addition, we describe how COVID-19 has changed the landscape of stroke systems of care and the effect this has had on patients with cerebrovascular disease.While COVID-19 is associated with a heightened risk of stroke, the pandemic has led to advances in stroke systems of care that may reduce the long-term burden of stroke.

OBJECTIVE: To evaluate whether patients discharged to home after an emergency department (ED) visit for headache face a heightened short-term risk of stroke. BACKGROUND: Stroke hospitalizations that occur soon after ED visits for headache complaints may reflect diagnostic error. METHODS: We conducted a retrospective cohort study using statewide administrative claims data for all ED visits and admissions at nonfederal hospitals in Florida 2005–2018 and New York 2005–2016. Using standard International Classification of Diseases (ICD) codes, we identified adult patients discharged to home from the ED (treat-and-release visit) with a benign headache diagnosis (cohort of interest) as well as those with a diagnosis of renal colic or back pain (negative controls). The primary study outcome was hospitalization within 30 days for stroke (ischemic or hemorrhagic) defined using validated ICD codes. We assess the relationship between index ED visit discharge diagnosis and stroke hospitalization adjusting for patient demographics and vascular comorbidities. RESULTS: We identified 1,502,831 patients with an ED treat-and-release headache visit; mean age was 41 (standard deviation: 17) years and 1,044,520 (70%) were female. A total of 2150 (0.14%) patients with headache were hospitalized for stroke within 30 days. In adjusted analysis, stroke risk was higher after headache compared to renal colic (hazard ratio [HR]: 2.69; 95% confidence interval [CI]: 2.29–3.16) or back pain (HR: 4.0; 95% CI: 3.74–4.3). In the subgroup of 26,714 (1.78%) patients with headache who received brain magnetic resonance imaging at index ED visit, stroke risk was only slightly elevated compared to renal colic (HR: 1.47; 95% CI: 1.22–1.78) or back pain (HR: 1.49; 95% CI: 1.24–1.80). CONCLUSION: Approximately 1 in 700 patients discharged to home from the ED with a headache diagnosis had a stroke in the following month. Stroke risk was three to four times higher after an ED visit for headache compared to renal colic or back pain.

ObjectiveTo estimate the incidence of hospitalization for reversible cerebral vasoconstriction syndrome (RCVS), we identified RCVS-related hospital admissions across 11 US states in 2016.MethodsWe tested the validity of ICD-10 code I67.841 in 79 patients with hospital admissions for RCVS or other cerebrovascular diseases at 1 academic and 1 community hospital. After determining that this code had a sensitivity of 100% (95% confidence interval [CI], 82%–100%) and a specificity of 90% (95% CI, 79%–96%), we applied it to administrative data from the Healthcare Cost and Utilization Project on all hospital admissions across 11 states. Age- and sex-standardized RCVS incidence was calculated using census data. Descriptive statistics were used to analyze associated diagnoses.ResultsAcross 5,067,250 hospital admissions in our administrative data, we identified 222 patients with a discharge diagnosis of RCVS in 2016. The estimated annual age- and sex-standardized incidence of RCVS hospitalization was 2.7 (95% CI, 2.4–3.1) cases per million adults. Many patients had concomitant neurologic diagnoses, including subarachnoid hemorrhage (37%), ischemic stroke (16%), and intracerebral hemorrhage (10%). In the 90 days before the index admission, 97 patients had an emergency department (ED) visit and 34 patients a hospital admission, most commonly for neurologic, psychiatric, and pregnancy-related diagnoses. Following discharge from the RCVS hospital admission, 58 patients had an ED visit and 31 had a hospital admission, most commonly for neurologic diagnoses.ConclusionsUsing population-wide data, we estimated the age- and sex-standardized incidence of hospitalization for RCVS in US adults as approximately 3 per million per year.

ObjectiveTo test the hypothesis that silent myocardial infarction (MI) is a risk factor for ischemic stroke, we evaluated the association between silent MI and subsequent ischemic stroke in the Cardiovascular Health Study.MethodsThe Cardiovascular Health Study prospectively enrolled community-dwelling individuals ≥65 years of age. We included participants without prevalent stroke or baseline evidence of MI. Our exposures were silent and clinically apparent, overt MI. Silent MI was defined as new evidence of Q-wave MI, without clinical symptoms of MI, on ECGs performed during annual study visits from 1989 to 1999. The primary outcome was incident ischemic stroke. Secondary outcomes were ischemic stroke subtypes: nonlacunar, lacunar, and other/unknown. Cox proportional hazards analysis was used to model the association between time-varying MI status (silent, overt, or no MI) and stroke after adjustment for baseline demographics and vascular risk factors.ResultsAmong 4,224 participants, 362 (8.6%) had an incident silent MI, 421 (10.0%) an incident overt MI, and 377 (8.9%) an incident ischemic stroke during a median follow-up of 9.8 years. After adjustment for demographics and comorbidities, silent MI was independently associated with subsequent ischemic stroke (hazard ratio [HR], 1.51; 95% confidence interval [CI], 1.03–2.21). Overt MI was associated with ischemic stroke both in the short term (HR, 80; 95% CI, 53–119) and long term (HR, 1.60; 95% CI, 1.04–2.44). In secondary analyses, the association between silent MI and stroke was limited to nonlacunar ischemic stroke (HR, 2.40; 95% CI, 1.36–4.22).ConclusionIn a community-based sample, we found an association between silent MI and ischemic stroke.

Cerebrovascular complications among critically ill patients with COVID-19 have yet to be fully characterized. In this retrospective case series from a single academic tertiary care referral center in New York City, we present 12 patients with ischemic or hemorrhagic strokes that were found on imaging after a period of prolonged sedation in the setting of COVID-19 pneumonia. This series demonstrates a pattern of cerebrovascular events clinically masked by deep sedation required for management of COVID-19 related acute respiratory distress syndrome (ARDS). Of the 12 patients included, 10 had ischemic stroke, 4 of which had hemorrhagic conversion, and 2 had primary intracerebral hemorrhage. Ten patients were on therapeutic anticoagulation prior to discovery of their stroke, and the remainder received intermediate dose anticoagulation (in a range between prophylactic and therapeutic levels). Additional studies are needed to further characterize the counterbalancing risks of ischemic and hemorrhagic stroke, as well as the optimal management of this patient population.

Background and Purpose: Recent studies suggest that alteration of the normal gut microbiome contributes to atherosclerotic burden and cardiovascular disease. While many gastrointestinal diseases are known to cause disruption of the normal gut microbiome in humans, the clinical impact of gastrointestinal diseases on subsequent cerebrovascular disease remains unknown. We conducted an exploratory analysis evaluating the relationship between gastrointestinal diseases and ischemic stroke. Methods: We performed a retrospective cohort study using claims between 2008 and 2015 from a nationally representative 5% sample of Medicare beneficiaries. We included only beneficiaries ≥66 years of age. We used previously validated diagnosis codes to ascertain our primary outcome of ischemic stroke. In an exploratory manner, we categorized gastrointestinal disorders by anatomic location, disease chronicity, and disease mechanism. We used Cox proportional hazards models to examine associations of gastrointestinal disorder categories and ischemic stroke with adjustment for demographics and established vascular risk factors. Results: Among a mean of 1 725 246 beneficiaries in each analysis, several categories of gastrointestinal disorders were associated with an increased risk of ischemic stroke after adjustment for established stroke risk factors. The most notable positive associations included disorders of the stomach (hazard ratio, 1.17 [95% CI, 1.15–1.19]) and functional (1.16 [95% CI, 1.15–1.17]), inflammatory (1.13 [95% CI, 1.12–1.15]), and infectious gastrointestinal disorders (1.13 [95% CI, 1.12–1.15]). In contrast, we found no associations with stroke for diseases of the anus and rectum (0.97 [95% CI, 0.94–1.00]) or neoplastic gastrointestinal disorders (0.97 [95% CI, 0.94–1.00]). Conclusions: In exploratory analyses, several categories of gastrointestinal disorders were associated with an increased risk of future ischemic stroke after adjustment for demographics and established stroke risk factors.

To derive models that identify patients with COVID-19 at high risk for stroke.We used data from the AHA's Get With The Guidelines® COVID-19 Cardiovascular Disease Registry to generate models for predicting stroke risk among adults hospitalized with COVID-19 at 122 centers from March 2020-March 2021. To build our models, we used data on demographics, comorbidities, medications, and vital sign and laboratory values at admission. The outcome was a cerebrovascular event (stroke, TIA, or cerebral vein thrombosis). First, we used Cox regression with cross validation techniques to identify factors associated with the outcome in both univariable and multivariable analyses. Then, we assigned points for each variable based on corresponding coefficients to create a prediction score. Second, we used machine learning techniques to create risk estimators using all available covariates.Among 21,420 patients hospitalized with COVID-19, 312 (1.5%) had a cerebrovascular event. Using traditional Cox regression, we created/validated a COVID-19 stroke risk score with a C-statistic of 0.66 (95% CI, 0.60-0.72). The CANDLE score assigns 1 point each for prior cerebrovascular disease, afebrile temperature, no prior pulmonary disease, history of hypertension, leukocytosis, and elevated systolic blood pressure. CANDLE stratified risk of an acute cerebrovascular event according to low- (0-1: 0.2% risk), medium- (2-3: 1.1% risk), and high-risk (4-6: 2.1-3.0% risk) groups. Machine learning estimators had similar discriminatory performance as CANDLE: C-statistics, 0.63-0.69.We developed a practical clinical score, with similar performance to machine learning estimators, to help stratify stroke risk among patients hospitalized with COVID-19.

Introduction: When a stroke hospitalization follows soon after an Emergency Department (ED) treat-and-release visit for non-specific neurological complaints, a diagnostic error may have occurred. In this study, we sought to evaluate potential stroke misdiagnoses after ED treat-and-release headache visits. Methods: We conducted a retrospective cohort study using state-wide administrative claims data for all ED visits and admissions at nonfederal hospitals in Florida 2005-2018 and New York 2005-2016. Using standard ICD codes, we identified adult patients discharged home from the ED with a benign headache diagnosis (cohort of interest) as well as those with a diagnosis of back pain or renal colic (negative control cohorts). The primary study outcome was hospitalization within 30 days for stroke (ischemic or hemorrhagic), defined using validated ICD codes. We used Cox proportional hazards modeling to assess the relationship between the index ED visit reason and stroke hospitalization adjusting for demographics and vascular risk factors. Results: We identified 1,458,904 patients with an ED treat-and-release headache visit; mean age was 41 (SD: 17) and 70% were female. A total of 2,636 (0.18%) headache patients were hospitalized for stroke within 30 days. Stroke risk was higher among headache patients compared to patients diagnosed with renal colic (HR: 2.7; 95% CI, 2.3-3.1) or back pain (HR: 3.8; 95% CI, 3.6-4.1; Figure). Among patients Conclusion: Approximately 1 in 500 patients discharged home from the ED with a headache diagnosis had a stroke in the following month. Stroke risk was 3-4 times higher after an ED visit for headache compared to back pain or renal colic. There may be opportunities to reduce diagnostic error among patients with ED visits for headache, particularly for those

Introduction: Posterior reversible encephalopathy syndrome (PRES) can cause brain infarction and hemorrhage in the acute phase. We hypothesized that PRES is also associated with an increased long-term risk of stroke. Methods: We performed a retrospective cohort study using statewide all-payer claims data from 2016-2018 for all admissions to nonfederal hospitals in 11 states. Adult patients with PRES were compared to patients with TIA (positive control) and renal colic (negative control), as done in prior studies. The primary outcome was any stroke, and secondary outcomes were ischemic and hemorrhagic stroke. Diagnoses were ascertained using ICD-10-CM codes. We excluded patients with stroke before and during index admissions for PRES and controls. We used Cox proportional hazards analyses to evaluate associations between PRES and stroke, adjusting for demographics, stroke risk factors, and factors associated with PRES (cancer, kidney disease, rheumatological disease). In a sensitivity analysis, stroke events within 4 weeks of index admissions were excluded. Results: We identified 3,086 patients with PRES, 85,189 with TIA, and 3,094 with renal colic. Patients with PRES (55±17 years) and renal colic (54±18 years) were younger than those with TIA (72±14 years). Median follow-up was 1.1 years and similar between groups. Stroke incidence was 3.2 per 100 person-years after PRES, 3.8 per 100 person-years after TIA, and 0.4 per 100 person-years after renal colic (Figure). After adjustment, patients with PRES had a similar stroke risk as patients with TIA (HR, 0.9; 95% CI, 0.8-1.2), and a higher stroke risk than patients with renal colic (HR, 2.6; 95% CI, 2.0-3.5). Compared to TIA, PRES had a higher risk of hemorrhagic stroke (HR, 2.9; 95% CI, 2.2-3.9) and a lower risk of ischemic stroke (HR, 0.7; 95% CI, 0.6-0.9). Results were similar with a 4-week washout period. Conclusions: PRES is associated with an increased risk of future stroke, specifically hemorrhagic stroke.

Introduction: Coronavirus Disease 2019 (COVID-19) is associated with an increased risk of stroke and worse stroke outcomes. A clinical score that can identify high-risk patients could enable closer monitoring and targeted preventative strategies. Methods: We used data from the AHA’s COVID-19 CVD Registry to create a clinical score to predict the risk of stroke among patients hospitalized with COVID-19. We included patients aged >18 years who were hospitalized with COVID-19 at 122 centers from March 2020-March 2021. To build our score, we used demographics, preexisting comorbidities, home medications, and vital sign and lab values at admission. The outcome was a cerebrovascular event, defined as any ischemic or hemorrhagic stroke, TIA, or cerebral vein thrombosis. We used two separate analytical approaches to build the score. First, we used Cox regression with cross validation techniques to identify factors associated with the outcome in both univariable (p Results: Among 21,420 patients hospitalized with COVID-19 (mean age 61 years, 54% men), 312 (1.5%) had a cerebrovascular event. Using traditional Cox regression, we created and internally validated a risk stratification score (CANDLE) (Fig) with a C-statistic of 0.66 (95% CI, 0.60-0.72). The machine learning estimator had similar discriminatory performance, with a C-statistic of 0.69 (95% CI, 0.65-0.72). For ischemic stroke or TIA, CANDLE’s C-statistic was 0.67 (95% 0.59-0.76). Conclusion: We developed an easy-to-use clinical score, with similar performance to a machine learning estimator, to help stratify stroke risk among patients hospitalized with COVID-19.

Introduction: Isolated amyloid deposition in the brain is associated with intracranial hemorrhage. Whether systemic amyloidosis also increases the risk of intracranial hemorrhage is unclear. Methods: We evaluated the association between systemic amyloidosis and intracranial hemorrhage using claims data from a 5% national sample of Medicare beneficiaries from 2008-2015. The primary outcome was non-traumatic intracranial hemorrhage, defined as a composite of intracerebral hemorrhage, subarachnoid hemorrhage, and subdural hemorrhage. Secondary outcome were each hemorrhage type assessed separately. The exposure and outcomes were identified using previously validated ICD-9-CM diagnosis codes. We used Cox regression analysis adjusting for demographics and vascular risk factors to evaluate the association between systemic amyloidosis and intracranial hemorrhage. We also examined the risk of hip fracture (negative control). In sensitivity analyses, we excluded patients with cardiac amyloidosis, a subset most likely to be on antithrombotic therapy. Results: Among 1.8 million Medicare beneficiaries, 924 were diagnosed with systemic amyloidosis. During a median follow-up of 5.3 years (IQR, 2.8- 6.7), the cumulative incidence of intracranial hemorrhage was 19 per 1,000 patients per year among patients with amyloidosis, and 2 per 1,000 patients per year in those without amyloidosis. In adjusted Cox models, systemic amyloidosis was associated with an increased risk of intracranial hemorrhage (HR, 4.3; 95% CI, 2.9-6.3). The association persisted in a sensitivity analysis after excluding beneficiaries with cardiac amyloidosis (HR, 8.0; 95% CI, 5.0-12.7). In secondary analyses, systemic amyloidosis was associated with intracerebral hemorrhage (HR, 5.6; 95% CI, 3.6-8.7), subarachnoid hemorrhage (HR, 14.7; 95% 9.0-24.0), and subdural hemorrhage (HR, 3.6; 95% 2.0-6.2). There was no association between systemic amyloidosis and hip fracture (HR, 0.9; 95% CI, 0.6-1.4). Conclusions: In a large, heterogeneous national cohort of elderly patients, a diagnosis of systemic amyloidosis was associated with a 4-fold increased risk of intracranial hemorrhage, including intracerebral, subarachnoid, and subdural hemorrhages.

Objective: To assess rates of postoperative stroke after elective noncardiac surgery in patients with atrial fibrillation (AF). Methods: We conducted a retrospective cohort study using all-payer administrative claims data on all non-federal hospitalizations and emergency department visits in 11 states between 2016 and 2018. We included patients hospitalized for elective noncardiac surgery, as defined by a surgical diagnosis related group and major diagnostic category codes. The exposure variable was preoperative AF. The outcome variable was ischemic stroke within 30 days of surgery. We performed survival analyses using Kaplan-Meier cumulative rates and Cox proportional hazards models. We stratified AF patients by their CHA 2 DS 2 -VASc score and tested its discrimination using the c-statistic. Results: We identified 1,301,709 patients undergoing elective noncardiac surgery, of whom 94,363 (7.3%) had preoperative AF. Patients with AF were older (mean age, 73 versus 62 years) and had higher CHA 2 DS 2 -VASc scores (mean score, 3.2 vs 2.2). We identified 2,893 patients with postoperative stroke. The cumulative rate of postoperative stroke was 0.65% (95% CI, 0.60-0.70%) in patients with AF vs 0.19% (95% CI, 0.18-0.20%) in patients without AF. After adjustment for demographics and vascular risk factors, AF was associated with a higher risk of postoperative stroke (HR, 1.7; 95% CI, 1.5-1.8). Among AF patients, the CHA 2 DS 2 -VASc score was a good predictor of postoperative stroke (AUC, 0.81; 95% CI, 0.79-0.83). Rates of postoperative stroke among AF patients ranged from 2 DS 2 -VASc score of 0-2 to 14% in those with a score of 8 (Figure). Conclusions: Patients with AF faced a heightened risk of postoperative stroke and this risk varied in proportion to the CHA 2 DS 2 -VASc score.

Introduction: Transthoracic echocardiography (TTE) is valuable in evaluating stroke etiology. A left ventricular (LV) thrombus, the identification of which can immediately impact clinical management, is rarely seen unless the ejection fraction (EF) is less than 50%. A clinical prediction score to identify stroke patients with EF less than 50% may help guide the timing of TTE after stroke. Methods: The CAESAR registry includes all patients with ischemic stroke at our medical center. We derived a clinical prediction score using CAESAR data from calendar years 2011-2016. We included all patients who underwent TTE and had a quantitative EF measurement. We selected clinical factors, laboratory values, and vital signs based on biological plausibility and the results of multiple logistical regression with backward selection. Results: Of 2,116 patients with ischemic stroke from 2011-2016, 1,045 patients had an EF measurement. The mean age was 63 (SD, 15), 49% were women, and the mean EF was 63% (SD, 14%). Reduced EF was identified in 171 patients (16%). Our final model comprised historical variables (coronary disease, heart failure, and chronic kidney disease) and clinical parameters from the time of admission (NIHSS score, heart rate, serum potassium, and serum creatinine). The model AUC was 0.80 (95% CI, 0.76-0.85) and model calibration was good (Figure). At a predicted probability threshold of 0.1, the score’s sensitivity for reduced EF was 80% with a specificity of 62%. In a sensitivity analysis excluding patients with atrial fibrillation, the AUC was 0.77 (95% CI 0.70-0.83) and calibration remained good. Conclusions: We derived a clinical score with good performance for predicting reduced EF in acute ischemic stroke patients. If externally validated, such a score may help identify which patients are most likely to benefit from an expedited inpatient TTE.

Background: The postpartum state is associated with a heightened risk of thrombosis. The duration of heightened risk for postpartum cerebral venous thrombosis (CVT) is uncertain. Methods: Using claims data from the Healthcare Cost and Utilization Project (HCUP) from all emergency departments and acute care hospitalizations in Florida from 2005-2015 and New York from 2006-2015, we identified women aged ≥18 years old who were hospitalized for labor and delivery. CVT was ascertained using previously validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), diagnosis codes. For women with multiple labor-related hospitalizations during a single 40-week period, we excluded cases of false labor by identifying delivery as the latest hospitalization during that time. Patients with claims for CVT before their first recorded delivery, and women with a second delivery during the follow-up period were also excluded. We compared the likelihood of a first-ever recorded CVT during postpartum days 0-41 compared with the same period 1 year later. We repeated this crossover-cohort analysis for consecutive 6-weeks periods after delivery, as compared with the corresponding 6-week period 1 year later. We used McNemar's to calculate odds ratios for each 6-week interval. Results: Among the 1,406,447 women with a first recorded delivery, the risk of CVT was markedly higher within the 6 weeks after delivery than in the same period 1 year later (22 versus 3 CVTs per million deliveries). This corresponded to an absolute risk difference of 19 events per million (95% confidence interval [CI], 11-27) and an odds ratio of 10.0 (95% CI, 3.1-51.2). There was no significant increase in the risk of CVT during the period of 7 to 12 weeks after delivery as compared with the same period 1 year later with an absolute risk difference of 6.0 events (95% CI, 0-11) per million deliveries and an odds ratio of 3.0 (95% CI, 0.9-12.8). Conclusion: There appears to be a heightened risk of CVT for 6 weeks after delivery.

Introduction: There is a known risk of ischemic stroke (IS) and mortality among patients with heart failure with reduced ejection fraction (HFrEF) and sinus rhythm. We identify predictors of IS and all-cause death in patients with left ventricular ejection fraction (LVEF) < 35% and sinus rhythm by a machine-learning approach. Methods: We performed a post-hoc analysis of the WARCEF trial which randomized patients with LVEF < 35% and sinus rhythm to either aspirin or warfarin. We built two Random Forest for Survival, Longitudinal, and Multivariate (RF-SLAM) algorithms to model the outcomes of IS and all-cause death separately using all baseline variables with missingness < 10%. The training data set was comprised of 70% of observations and the testing set of the remaining 30%. To assess variable importance in outcome prediction, Mean Decrease Accuracy was computed for each variable over all out-of-bag cross-validated predictions. Results: In 2,298 participants (median age 61.5 years [IQR 54.3-69.6], 20% female) during a mean follow-up of 3.5 years (SD 1.8 years), 84 (3.7%) patients had an ischemic stroke and 547 (23.8%) died. Patient-specific characteristics contributing most to ischemic stroke prediction with variable Mean Decrease Accuracies ≥ 2.5 were prior transient ischemic attack, CHA 2 DS 2 -VASc score, age, prior stroke, glucose, and blood urea nitrogen (model accuracy 0.95; 95% C.I. 0.93-0.97). Age, hemoglobin, glucose, INR, platelet count, BUN, and systolic blood pressure were the most important patient-specific predictors of all-cause death with variable Mean Decrease Accuracies ≥ 2.5 (model accuracy 0.76; 95% C.I. 0.72-0.79). Conclusions: Clinical and serologic characteristics identified by the RF-SLAM algorithm predict IS and all-cause death risks in patients with HFrEF and sinus rhythm. Future studies are needed to assess the impact of these factors on treatment effects in heart failure trials evaluating outcomes which include stroke.

ObjectiveTo evaluate the relationship between prior antiplatelet therapy (APT) and outcomes after primary intracerebral haemorrhage (ICH), and assess if it varies by haematoma location.MethodsWe pooled individual patient data from the Virtual International Stroke Trials Archive-ICH trials dataset, Clot Lysis: Evaluating Accelerated Resolution of Intraventricular Hemorrhage III trial and the Minimally Invasive Surgery Plus Alteplase for Intracerebral Hemorrhage Evacuation Phase III trial. The exposure was APT preceding ICH diagnosis. The primary outcome was haematoma expansion at 72 hours. Secondary outcomes were admission haematoma volume, all-cause mortality, death or major disability (modified Rankin Scale (mRS) score ≥4) and shift in mRS distribution. Mixed-effects models were used to assess the relationship between APT and outcomes. Secondary analyses were stratified by ICH location and study cohort.ResultsAmong 1420 patients with ICH, there were 782 (55.1%) lobar and 596 (42.0%) deep haemorrhages. APT was reported in 284 (20.0%) patients. In adjusted regression models, prior APT was not associated with haematoma expansion (OR, 0.97; 95% CI 0.60 to 1.57), major disability or death (OR, 1.05; 95% CI 0.61 to 1.63), all-cause mortality (OR, 0.89; 95% CI 0.47 to 1.85), admission haematoma volume (beta, −0.17; SE, 0.09; p=0.07) and shift in mRS (p=0.43). In secondary analyses, APT was associated with admission haematoma volume in lobar ICH (beta, 0.25; SE, 0.12; p=0.03), but there was no relationship with other ICH outcomes when stratified by haematoma location or study cohort.ConclusionsIn a large heterogeneous cohort of patients with ICH, prior APT was not associated with haematoma expansion or functional outcomes after ICH, regardless of haematoma location. APT was associated with admission haematoma volumes in lobar ICH.

Objective We wanted to determine whether pregnancy is associated with cervical artery dissection. Methods We performed a case-control study using claims data from all nonfederal emergency departments and acute care hospitals in New York and Florida between 2005 and 2015. Cases were women 12-42 years of age hospitalized with cervical artery dissection, defined using validated diagnosis codes for carotid/vertebral artery dissection. Controls were women 12-42 years of age with a primary diagnosis of renal colic. Cases and controls were matched 1:1 on age, race, insurance, income, state, and visit year. The exposure variable was pregnancy, defined as labor and delivery within 90 days before or 6 months after the index visit. Logistic regression was used to compare the odds of pregnancy between cases and controls. We performed a secondary cohort-crossover study comparing the risk of cervical artery dissection during pregnancy versus the same time period 1 year later. Results Pregnancy was twice as common among 826 women with cervical artery dissection compared with the 826 matched controls with renal colic (odds ratio, 2.5; 95% confidence interval [CI], 1.3-4.7). In our secondary analysis, pregnancy was associated with a higher risk of cervical artery dissection (incidence rate ratio [IRR], 2.2; 95% CI, 1.3-3.5), with the heightened risk limited to the postpartum period (IRR, 5.5; 95% CI, 2.6-11.7). Interpretation Pregnancy, specifically the postpartum period, was associated with hospitalization for cervical artery dissection. Although these findings might in part reflect ascertainment bias, our results suggest that arterial dissection is one mechanism by which pregnancy can lead to stroke. ANN NEUROL 2020;88:596-602.

Background and Purpose— Patients who continue to smoke after a stroke face a higher risk of recurrent stroke. While several effective drugs for smoking cessation became available over the past 2 decades, whether active smoking has decreased among stroke survivors is unknown. We, therefore, evaluated trends in active smoking among stroke survivors during this period. Methods— We performed trends analyses using cross-sectional data collected every 1 to 2 years from 2 US health surveys spanning 1999 to 2018. In the National Health and Nutrition Examination Survey (NHANES) and the Behavioral Risk Factor Surveillance System (BRFSS) survey, participants were asked about prior stroke and active tobacco smoking. In NHANES, serum cotinine levels were available as a secondary measure of active smoking. We used multivariable logistic regression models for survey data to assess trends in active smoking among participants with and without prior stroke. Results— Among 49 375 participants in NHANES during 1999 to 2016 and 3 621 741 participants in BRFSS during 2011 to 2018, the prevalence of stroke was ≈3%. The overall prevalence of active smoking among stroke survivors was 24% in NHANES and 23% in BRFSS. Among individuals without prior stroke, the odds of smoking decreased over time in both NHANES (odds ratio, 0.95 per 2 years [95% CI, 0.93–0.96]) and BRFSS (odds ratio, 0.96 per year [95% CI, 0.96–0.96]). In contrast, there was no decrease in smoking among stroke survivors in NHANES (odds ratio, 1.00 [95% CI, 0.93–1.07]) or BRFSS (odds ratio, 0.99 [95% CI, 0.98–1.004]). Results were consistent in secondary analysis using biochemical ascertainment of active smoking in NHANES and in sensitivity analyses accounting for potential demographic changes in stroke epidemiology. Conclusions— In contrast to the general population, the prevalence of active smoking among stroke survivors has not decreased during the past 2 decades.

Background and Purpose— The risk of arterial ischemic events after subdural hemorrhage (SDH) is poorly understood. This study aimed to evaluate the risk of acute ischemic stroke and myocardial infarction among patients with and without nontraumatic SDH. Methods— We performed a retrospective cohort study using claims data from 2008 through 2014 from a nationally representative sample of Medicare beneficiaries. The exposure was nontraumatic SDH. Our primary outcome was an arterial ischemic event, a composite of acute ischemic stroke and acute myocardial infarction. Secondary outcomes were ischemic stroke alone and myocardial infarction alone. We used validated International Classification of Diseases , Ninth Revision , Clinical Modification diagnosis codes to identify our predictor and outcomes. Using Cox regression and corresponding survival probabilities, adjusted for demographics and vascular comorbidities, we computed the hazard ratio in 4-week intervals after SDH discharge. We performed secondary analyses stratified by strong indications for antithrombotic therapy (composite of atrial fibrillation, peripheral vascular disease, valvular heart disease, and venous thromboembolism). Results— Among 1.7 million Medicare beneficiaries, 2939 were diagnosed with SDH. In the 4 weeks after SDH, patients’ risk of an arterial ischemic event was substantially increased (hazard ratio, 3.6 [95% CI, 1.9–5.5]). There was no association between SDH diagnosis and arterial ischemic events beyond 4 weeks. In secondary analysis, during the 4 weeks after SDH, patients’ risk of ischemic stroke was increased (hazard ratio, 4.2 [95% CI, 2.1–7.3]) but their risk of myocardial infarction was not (hazard ratio, 0.8 [95% CI, 0.2–1.7]). Patients with strong indications for antithrombotic therapy had increased risks for arterial ischemic events similar to patients in the primary analysis, but those without such indications did not demonstrate an increased risk for arterial ischemic events. Conclusions— Among Medicare beneficiaries, we found a heightened risk of arterial ischemic events driven by an increased risk of ischemic stroke, in the 4 weeks after nontraumatic SDH. This increased risk may be due to interruption of antithrombotic therapy after SDH diagnosis.