MRI in the Evaluation of Cryptogenic Stroke and Embolic Stroke of Undetermined Source

Cryptogenic stroke refers to a stroke of undetermined etiology. It accounts for approximately one-fifth of ischemic strokes and has a higher prevalence in younger patients. Embolic stroke of undetermined source (ESUS) refers to a subgroup of patients with nonlacunar cryptogenic strokes in whom embolism is the suspected stroke mechanism. Under the classifications of cryptogenic stroke or ESUS, there is wide heterogeneity in possible stroke mechanisms. In the absence of a confirmed stroke etiology, there is no established treatment for secondary prevention of stroke in patients experiencing cryptogenic stroke or ESUS, despite several clinical trials, leaving physicians with a clinical dilemma. Both conventional and advanced MRI techniques are available in clinical practice to identify differentiating features and stroke patterns and to determine or infer the underlying etiologic cause, such as atherosclerotic plaques and cardiogenic or paradoxical embolism due to occult pelvic venous thrombi. The aim of this review is to highlight the diagnostic utility of various MRI techniques in patients with cryptogenic stroke or ESUS. Future trends in technological advancement for promoting the adoption of MRI in such a special clinical application are also discussed.

Distinctive retinal peri-arteriolar versus peri-venular amyloid plaque distribution correlates with the cognitive performance

Introduction

The vascular contribution to Alzheimer's disease (AD) is tightly connected to cognitive performance across the AD continuum. We topographically describe retinal perivascular amyloid plaque (AP) burden in subjects with normal or impaired cognition.

Methods

Using scanning laser ophthalmoscopy, we quantified retinal peri-arteriolar and peri-venular curcumin-positive APs in the first, secondary and tertiary branches in twenty-eight subjects. Perivascular AP burden among cognitive states was correlated with neuroimaging and cognitive measures.

Results

Peri-arteriolar exceeded peri-venular AP count (p<0.0001). Secondary branch AP count was significantly higher in cognitively impaired (p<0.01). Secondary small and tertiary peri-venular AP count strongly correlated with clinical dementia rating, hippocampal volumes, and white matter hyperintensity count.

Discussion

Our topographic analysis indicates greater retinal amyloid accumulation in the retinal peri-arteriolar regions overall, and distal peri-venular regions in cognitively impaired individuals. Larger longitudinal studies are warranted to understand the temporal-spatial relationship between vascular dysfunction and perivascular amyloid deposition in AD.

Highlights

Retinal peri-arteriolar region exhibits more amyloid compared with peri-venular regions.Secondary retinal vascular branches have significantly higher perivascular amyloid burden in subjects with impaired cognition, consistent across sexes.Cognitively impaired individuals have significantly greater retinal peri-venular amyloid deposits in the distal small branches, that correlate with CDR and hippocampal volumes.

New Picture Stimuli for the NIH Stroke Scale: A Validation Study

BACKGROUND

The National Institutes of Health Stroke Scale is a widely accepted tool for structured graded neurological examination of stroke or suspected stroke in the hyperacute setting. Concerns have arisen about the use of its picture stimuli in a contemporary and global health context. Here, we present new stimuli prepared to serve the needs of stroke providers worldwide: the precarious painter image description and updated objects for naming.

METHODS

This was a validation study of 101 healthy fluent English speakers. Participants were reached by the Johns Hopkins Outpatient Center, the University of South Carolina, and Prisma Health from 2022 to 2023 and included residents of the United States, Germany, Canada, the United Kingdom, Australia, and Zambia. Participants were recorded in person or via video conferencing when asked to describe the new picture, while a subset named seven illustrations. Multivariate analyses of variance were used for primary analyses. In a complementary investigation, 299 attendees of the 2023 International Stroke Conference were asked about their preference for the existing or new stimuli and why.

RESULTS

Each of the 44 content units from the picture description was included by at least 5% of respondents in the demographically representative subsample. Performance was similar across healthy participants irrespective of age, sex, race, ethnicity, or education. Typical descriptions were characterized by an average of 23 content units (SD=5) conveyed with 167 syllables (SD=79). The new naming stimuli were recognized by 100% of participants from many countries as being familiar and identifiable, and names provided in response to the task were highly convergent. The majority of stroke health care providers preferred both the precarious painter and naming stimuli.

CONCLUSIONS

The description of the new National Institutes of Health Stroke Scale picture, the precarious painter, results in rich samples among healthy speakers that will provide an appropriate basis for the detection of language deficits.

Post-Traumatic Cerebral Infarction: A Narrative Review of Pathophysiology, Diagnosis, and Treatment

Traumatic brain injury (TBI) is a common diagnosis requiring acute hospitalization. Long-term, TBI is a significant source of health and socioeconomic impact in the United States and globally. The goal of clinicians who manage TBI is to prevent secondary brain injury. In this population, post-traumatic cerebral infarction (PTCI) acutely after TBI is an important but under-recognized complication that is associated with negative functional outcomes. In this comprehensive review, we describe the incidence and pathophysiology of PTCI. We then discuss the diagnostic and treatment approaches for the most common etiologies of isolated PTCI, including brain herniation syndromes, cervical artery dissection, venous thrombosis, and post-traumatic vasospasm. In addition to these mechanisms, hypercoagulability and microcirculatory failure can also exacerbate ischemia. We aim to highlight the importance of this condition and future clinical research needs with the goal of improving patient outcomes after TBI.

Priorities for Advancements in Neuroimaging in the Diagnostic Workup of Acute Stroke

STAIR XII (12th Stroke Treatment Academy Industry Roundtable) included a workshop to discuss the priorities for advancements in neuroimaging in the diagnostic workup of acute ischemic stroke. The workshop brought together representatives from academia, industry, and government. The participants identified 10 critical areas of priority for the advancement of acute stroke imaging. These include enhancing imaging capabilities at primary and comprehensive stroke centers, refining the analysis and characterization of clots, establishing imaging criteria that can predict the response to reperfusion, optimizing the Thrombolysis in Cerebral Infarction scale, predicting first-pass reperfusion outcomes, improving imaging techniques post-reperfusion therapy, detecting early ischemia on noncontrast computed tomography, enhancing cone beam computed tomography, advancing mobile stroke units, and leveraging high-resolution vessel wall imaging to gain deeper insights into pathology. Imaging in acute ischemic stroke treatment has advanced significantly, but important challenges remain that need to be addressed. A combined effort from academic investigators, industry, and regulators is needed to improve imaging technologies and, ultimately, patient outcomes.

Immunonutrition with Omega-3 Fatty Acid Supplementation in Severe TBI: Retrospective Analysis of Patient Characteristics and Outcomes

Background

Early evidence-based medical interventions to improve patient outcomes after traumatic brain injury (TBI) are lacking. In patients admitted to the ICU after TBI, optimization of nutrition is an emerging field of interest. Specialized enteral nutrition (EN) formulas that include immunonutrition containing omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been developed and are used for their proposed anti-inflammatory and pro-immune properties; however, their use has not been rigorously studied in human TBI populations.

Methods

A single-center, retrospective, descriptive observational study was conducted at LAC + USC Medical Center. Patients with severe TBI (sTBI, Glasgow Coma Scale score ≤ 8) who remained in the ICU for ≥ 2 weeks and received EN were identified between 2017 and 2022 using the institutional trauma registry. Those who received immunonutrition formulas containing n-3 PUFAs were compared to those who received standard, polymeric EN in regard to baseline characteristics, clinical markers of inflammation and immune function, and short-term clinical outcomes.

Results

A total of 151 patients with sTBI were analyzed. Those who received immunonutrition with n-3 PUFA supplementation were more likely to be male, younger, Hispanic/Latinx, and have polytrauma needing non-central nervous system surgery. No differences in clinical markers of inflammation or infection rate were found. In multivariate regression analysis, immunonutrition was associated with reduced hospital length of stay (LOS). ICU LOS was also reduced in the subgroup of patients with polytrauma and TBI.

Conclusion

This study identifies important differences in patient characteristics and outcomes associated with the EN formula prescribed. Study results can directly inform a prospective pragmatic study of immunonutrition with n-3 PUFA supplementation aimed to confirm the biomechanistic and clinical benefits of the intervention.

Enhancing Enrollment in Acute Stroke Trials: Current State and Consensus Recommendations

The Stroke Treatment Academic Industry Roundtable (STAIR) convened a session and workshop regarding enrollment in acute stroke trials during the STAIR XII meeting on March 22, 2023. This forum brought together stroke physicians and researchers, members of the National Institute of Neurological Disorders and Stroke, industry representatives, and members of the US Food and Drug Administration to discuss the current status and opportunities for improving enrollment in acute stroke trials. The workshop identified the most relevant issues impacting enrollment in acute stroke trials and addressed potential action items for each. Focus areas included emergency consent in the United States and other countries; careful consideration of eligibility criteria to maximize enrollment and representativeness; investigator, study coordinator, and pharmacist availability outside of business hours; trial enthusiasm/equipoise; site start-up including contractual issues; site champions; incorporation of study procedures into standard workflow as much as possible; centralized enrollment at remote sites by study teams using telemedicine; global trials; and coenrollment in trials when feasible. In conclusion, enrollment of participants is the lifeblood of acute stroke trials and is the rate-limiting step for testing an exciting array of new approaches to improve patient outcomes. In particular, efforts should be undertaken to broaden the medical community's understanding and implementation of emergency consent procedures and to adopt designs and processes that are easily incorporated into standard workflow and that improve trials' efficiencies and execution. Research and actions to improve enrollment in ongoing and future trials will improve stroke outcomes more broadly than any single therapy under consideration.

A multi-laboratory preclinical trial in rodents to assess treatment candidates for acute ischemic stroke

Human diseases may be modeled in animals to allow preclinical assessment of putative new clinical interventions. Recent, highly publicized failures of large clinical trials called into question the rigor, design, and value of preclinical assessment. We established the Stroke Preclinical Assessment Network (SPAN) to design and implement a randomized, controlled, blinded, multi-laboratory trial for the rigorous assessment of candidate stroke treatments combined with intravascular thrombectomy. Efficacy and futility boundaries in a multi-arm multi-stage statistical design aimed to exclude from further study highly effective or futile interventions after each of four sequential stages. Six independent research laboratories performed a standard focal cerebral ischemic insult in five animal models that included equal numbers of males and females: young mice, young rats, aging mice, mice with diet-induced obesity, and spontaneously hypertensive rats. The laboratories adhered to a common protocol and efficiently enrolled 2615 animals with full data completion and comprehensive animal tracking. SPAN successfully implemented treatment masking, randomization, prerandomization inclusion and exclusion criteria, and blinded assessment of outcomes. The SPAN design and infrastructure provide an effective approach that could be used in similar preclinical, multi-laboratory studies in other disease areas and should help improve reproducibility in translational science.

Optimization of Nutrition after Brain Injury: Mechanistic and Therapeutic Considerations

Emerging science continues to establish the detrimental effects of malnutrition in acute neurological diseases such as traumatic brain injury, stroke, status epilepticus and anoxic brain injury. The primary pathological pathways responsible for secondary brain injury include neuroinflammation, catabolism, immune suppression and metabolic failure, and these are exacerbated by malnutrition. Given this, there is growing interest in novel nutritional interventions to promote neurological recovery after acute brain injury. In this review, we will describe how malnutrition impacts the biomolecular mechanisms of secondary brain injury in acute neurological disorders, and how nutritional status can be optimized in both pediatric and adult populations. We will further highlight emerging therapeutic approaches, including specialized diets that aim to resolve neuroinflammation, immunodeficiency and metabolic crisis, by providing pre-clinical and clinical evidence that their use promotes neurologic recovery. Using nutrition as a targeted treatment is appealing for several reasons that will be discussed. Given the high mortality and both short- and long-term morbidity associated with acute brain injuries, novel translational and clinical approaches are needed.

Bias in Stroke Evaluation: Rethinking the Cookie Theft Picture

Despite a current emphasis on equity in stroke care, one of the most common stroke assessment tools that is used both nationally and internationally, includes an anachronistic image that projects cultural, linguistic, and socioeconomic bias. This image, titled The Cookie Theft picture, is included in the National Institutes of Health Stroke Scale and was originally developed in 1972. Now, 50 years later, it does not reflect our current diverse, linguistically rich, and multicultural patient population.

The Stroke Preclinical Assessment Network: Rationale, Design, Feasibility, and Stage 1 Results

Cerebral ischemia and reperfusion initiate cellular events in brain that lead to neurological disability. Investigating these cellular events provides ample targets for developing new treatments. Despite considerable work, no such therapy has translated into successful stroke treatment. Among other issues-such as incomplete mechanistic knowledge and faulty clinical trial design-a key contributor to prior translational failures may be insufficient scientific rigor during preclinical assessment: nonblinded outcome assessment; missing randomization; inappropriate sample sizes; and preclinical assessments in young male animals that ignore relevant biological variables, such as age, sex, and relevant comorbid diseases. Promising results are rarely replicated in multiple laboratories. We sought to address some of these issues with rigorous assessment of candidate treatments across 6 independent research laboratories. The Stroke Preclinical Assessment Network (SPAN) implements state-of-the-art experimental design to test the hypothesis that rigorous preclinical assessment can successfully reduce or eliminate common sources of bias in choosing treatments for evaluation in clinical studies. SPAN is a randomized, placebo-controlled, blinded, multilaboratory trial using a multi-arm multi-stage protocol to select one or more putative stroke treatments with an implied high likelihood of success in human clinical stroke trials. The first stage of SPAN implemented procedural standardization and experimental rigor. All participating research laboratories performed middle cerebral artery occlusion surgery adhering to a common protocol and rapidly enrolled 913 mice in the first of 4 planned stages with excellent protocol adherence, remarkable data completion and low rates of subject loss. SPAN stage 1 successfully implemented treatment masking, randomization, prerandomization inclusion/exclusion criteria, and blinded assessment to exclude bias. Our data suggest that a large, multilaboratory, preclinical assessment effort to reduce known sources of bias is feasible and practical. Subsequent SPAN stages will evaluate candidate treatments for potential success in future stroke clinical trials using aged animals and animals with comorbid conditions.

Pro-resolving lipid mediators in traumatic brain injury: emerging concepts and translational approach

Despite the high mortality and disability associated with traumatic brain injury (TBI), effective pharmacologic treatments are lacking. Of emerging interest, bioactive lipids, including specialized pro-resolving lipid mediators of inflammation (SPMs), act to attenuate inflammation after injury resolution. The SPM lipidome may serve as a biomarker of disease and predictor of clinical outcomes, and the use of exogenous SPM administration represents a novel therapeutic strategy for TBI. This review article provides a comprehensive discussion of the current pre-clinical and clinical literature supporting the importance of bioactive lipids, including SPMs, in TBI recovery. We additionally propose a translational approach to answer important clinical and scientific questions to advance the study of bioactive lipids and SPMs towards clinical research. Given the morbidity and mortality associated with TBI with limited treatment options, novel approaches are needed.

Association of Recent Use of Non-Vitamin K Antagonist Oral Anticoagulants With Intracranial Hemorrhage Among Patients With Acute Ischemic Stroke Treated With Alteplase

IMPORTANCE

Current guidelines recommend against use of intravenous alteplase in patients with acute ischemic stroke who are taking non-vitamin K antagonist oral anticoagulants (NOACs).

OBJECTIVE

To evaluate the safety and functional outcomes of intravenous alteplase among patients who were taking NOACs prior to stroke and compare outcomes with patients who were not taking long-term anticoagulants.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study of 163 038 patients with acute ischemic stroke either taking NOACs or not taking anticoagulants prior to stroke and treated with intravenous alteplase within 4.5 hours of symptom onset at 1752 US hospitals participating in the Get With The Guidelines-Stroke program between April 2015 and March 2020, with complementary data from the Addressing Real-world Anticoagulant Management Issues in Stroke registry.

EXPOSURES

Prestroke treatment with NOACs within 7 days prior to alteplase treatment.

MAIN OUTCOMES AND MEASURES

The primary outcome was symptomatic intracranial hemorrhage occurring within 36 hours after intravenous alteplase administration. There were 4 secondary safety outcomes, including inpatient mortality, and 7 secondary functional outcomes assessed at hospital discharge, including the proportion of patients discharged home.

RESULTS

Of 163 038 patients treated with intravenous alteplase (median age, 70 [IQR, 59 to 81] years; 49.1% women), 2207 (1.4%) were taking NOACs and 160 831 (98.6%) were not taking anticoagulants prior to their stroke. Patients taking NOACs were older (median age, 75 [IQR, 64 to 82] years vs 70 [IQR, 58 to 81] years for those not taking anticoagulants), had a higher prevalence of cardiovascular comorbidities, and experienced more severe strokes (median National Institutes of Health Stroke Scale score, 10 [IQR, 5 to 17] vs 7 [IQR, 4 to 14]) (all standardized differences >10). The unadjusted rate of symptomatic intracranial hemorrhage was 3.7% (95% CI, 2.9% to 4.5%) for patients taking NOACs vs 3.2% (95% CI, 3.1% to 3.3%) for patients not taking anticoagulants. After adjusting for baseline clinical factors, the risk of symptomatic intracranial hemorrhage was not significantly different between groups (adjusted odds ratio [OR], 0.88 [95% CI, 0.70 to 1.10]; adjusted risk difference [RD], -0.51% [95% CI, -1.36% to 0.34%]). There were no significant differences in the secondary safety outcomes, including inpatient mortality (6.3% for patients taking NOACs vs 4.9% for patients not taking anticoagulants; adjusted OR, 0.84 [95% CI, 0.69 to 1.01]; adjusted RD, -1.20% [95% CI, -2.39% to -0%]). Of the secondary functional outcomes, 4 of 7 showed significant differences in favor of the NOAC group after adjustment, including the proportion of patients discharged home (45.9% vs 53.6% for patients not taking anticoagulants; adjusted OR, 1.17 [95% CI, 1.06 to 1.29]; adjusted RD, 3.84% [95% CI, 1.46% to 6.22%]).

CONCLUSIONS AND RELEVANCE

Among patients with acute ischemic stroke treated with intravenous alteplase, use of NOACs within the preceding 7 days, compared with no use of anticoagulants, was not associated with a significantly increased risk of intracranial hemorrhage.

Disparate trends of atherosclerotic plaque evolution in stroke patients under 18-month follow-up: a 3D whole-brain magnetic resonance vessel wall imaging study

PURPOSE

The trend of atherosclerotic plaque feature evolution is unclear in stroke patients with and without recurrence. We aimed to use three-dimensional whole-brain magnetic resonance vessel wall imaging to quantify the morphological changes of causative lesions during medical therapy in patients with symptomatic intracranial atherosclerotic disease.

METHODS

Patients with acute ischemic stroke attributed to intracranial atherosclerotic disease were retrospectively enrolled if they underwent both baseline and follow-up magnetic resonance vessel wall imaging. The morphological features of the causative plaque, including plaque volume, peak normalized wall index, maximum wall thickness, degree of stenosis, pre-contrast plaque-wall contrast ratio, and post-contrast plaque enhancement ratio, were quantified and compared between the non-recurrent and recurrent groups (defined as the recurrence of a vascular event within 18 months of stroke).

RESULTS

Twenty-nine patients were included in the final analysis. No significant differences were found in plaque features in the baseline scan between the non-recurrent (n = 22) and recurrent groups (n = 7). The changes in maximum wall thickness (-13.32% vs. 8.93%, P = 0.026), plaque-wall contrast ratio (-0.82% vs. 3.42%, P = 0.005) and plaque enhancement ratio (-11.03% vs. 9.75%, P = 0.019) were significantly different between the non-recurrent and recurrent groups. Univariable logistic regression showed that the increase in plaque-wall contrast ratio (odds ratio 3.22, 95% confidence interval 1.55-9.98, P = 0.003) was related to stroke recurrence.

CONCLUSION

Morphological changes of plaque features on magnetic resonance vessel wall imaging demonstrated distinct trends in symptomatic intracranial atherosclerotic disease patients with and without stroke recurrence.

Retinal Venular Tortuosity Jointly with Retinal Amyloid Burden Correlates with Verbal Memory Loss: A Pilot Study

Introduction: Retinal imaging is a non-invasive tool to study both retinal vasculature and neurodegeneration. In this exploratory retinal curcumin-fluorescence imaging (RFI) study, we sought to determine whether retinal vascular features combined with retinal amyloid burden correlate with the neurocognitive status. Methods: We used quantitative RFI in a cohort of patients with cognitive impairment to automatically compute retinal amyloid burden. Retinal blood vessels were segmented, and the vessel tortuosity index (VTI), inflection index, and branching angle were quantified. We assessed the correlations between retinal vascular and amyloid parameters, and cognitive domain Z-scores using linear regression models. Results: Thirty-four subjects were enrolled and twenty-nine (55% female, mean age 64 ± 6 years) were included in the combined retinal amyloid and vascular analysis. Eleven subjects had normal cognition and 18 had impaired cognition. Retinal VTI was discriminated among cognitive scores. The combined proximal mid-periphery amyloid count and venous VTI index exhibited significant differences between cognitively impaired and cognitively normal subjects (0.49 ± 1.1 vs. 0.91 ± 1.4, p = 0.006), and correlated with both the Wechsler Memory Scale-IV and SF-36 mental component score Z-scores (p < 0.05). Conclusion: This pilot study showed that retinal venular VTI combined with the proximal mid-periphery amyloid count could predict verbal memory loss. Future research is needed to finesse the clinical application of this retinal imaging-based technology.

Cerebroprotection for Acute Ischemic Stroke: Looking Ahead

We search for ischemic stroke treatment knowing we have failed-intensely and often-to translate mechanistic knowledge into treatments that alleviate our patients' functional impairments. Lessons can be derived from our shared failures that may point to new directions and new strategies. First, the principle criticisms of both preclinical and clinical assessments are summarized. Next, previous efforts to develop single-mechanism treatments are reviewed. Finally, new definitions, novel approaches, and different directions are presented. In previous development efforts, the basic science and preclinical assessment of candidate treatments often lacked rigor and sufficiency; the clinical trials may have lacked power, rigor, or rectitude; or most likely both preclinical and clinical investigations were flawed. Single-target agents directed against specific molecular mechanisms proved unsuccessful. The term neuroprotection should be replaced as it has become ambiguous: protection of the entire neurovascular unit may be called cerebral cytoprotection or cerebroprotection. Success in developing cerebroprotection-either as an adjunct to recanalization or as stand-alone treatment-will require new definitions that recognize the importance of differential vulnerability in the neurovascular unit. Recent focus on pleiotropic multi-target agents that act via multiple mechanisms of action to interrupt ischemia at multiple steps may be more fruitful. Examples of pleiotropic treatments include therapeutic hypothermia and 3K3A-APC (activated protein C). Alternatively, the single-target drug NA-1 triggers multiple downstream signaling events. Renewed commitment to scientific rigor is essential, and funding agencies and journals may enforce quality principles of rigor in preclinical science. Appropriate animal models should be selected that are suited to the purpose of the investigation. Before clinical trials, preclinical assessment could include subjects that are aged, of both sexes, and harbor comorbid conditions such as diabetes or hypertension. With these new definitions, novel approaches, and renewed attention to rigor, the prospect for successful cerebroprotective therapy should improve.

COVID-19 Impact on Acute Ischemic Stroke Treatment at 9 Comprehensive Stroke Centers across Los Angeles

Objective

To describe the impact of COVID-19 on acute cerebrovascular disease care across 9 comprehensive stroke centers throughout Los Angeles County (LAC).

Methods

Volume of emergency stroke code activations, patient characteristics, stroke severity, reperfusion rates, treatment times, and outcomes from February 1 to April 30, 2020, were compared against the same time period in 2019. Demographic data were provided by each participating institution.

Results

There was a 17.3% decrease in stroke code activations across LAC in 2020 compared to 2019 (1,786 vs. 2,159, respectively, χ² goodness of fit test p < 0.0001) across 9 participating comprehensive stroke centers. Patients who did not receive any reperfusion therapy decreased by 16.6% in 2020 (1,527) compared to 2019 (1,832). Patients who received only intravenous thrombolytic (IVT) therapy decreased by 31.8% (107 vs. 157). Patients who received only mechanical thrombectomy (MT) increased by 3% (102 vs. 99). Patients who received both IVT and MT decreased by 31.8% (45 vs. 66). Recanalization treatment times in 2020 were comparable to 2019. CSCs serving a higher proportion of Latinx populations in the eastern parts of LAC experienced a higher incidence of MT in 2020 compared to 2019. Mild increase in stroke severity was seen in 2020 compared to 2019 (8.95 vs. 8.23, p = 0.046). A higher percentage of patients were discharged home in 2020 compared to 2019 (59.5 vs. 56.1%, p = 0.034), a lower percentage of patients were discharged to skilled nursing facility (16.1 vs. 20.7%, p = 0.0004), and a higher percentage of patients expired (8.6 vs. 6.3%, p = 0.008).

Conclusion

LAC saw a decrease in overall stroke code activations in 2020 compared to 2019. Reperfusion treatment times remained comparable to prepandemic metrics. There has been an increase in severe stroke incidence and higher volume of thrombectomy treatments in Latinx communities within LAC during the pandemic of 2020. More patients were discharged home, less patients discharged to skilled nursing facilities, and more patients expired in 2020, compared to the same time frame in 2019.

Abstract P55: Retinal Microvascular Parameters Predict Retinal Amyloid Burden and Co-Jointly Predict Verbal Memory

Introduction: Retinal vascular features predict cognitive performance and retinal imaging is a non-invasive tool to study brain health. Patients with Alzheimer’s disease (AD)-related cognitive disorders exhibit both retinal vascular abnormalities and intraretinal accumulation of amyloid-beta (Aβ) plaque. Curcumin-enhanced retinal fluorescence imaging (CRFI) was recently translated as a safe imaging tool for retinal Aβ plaque quantification. In this study, we sought to determine whether and which retinal arterial and venous parameters are predictive of retinal Aβ burden and cognitive Z-scores.

Methods: We used scanning laser ophthalmoscopy with RetiaTM (Centervue, Inc) to obtain CRFI in a cohort of patients with cognitive decline. Retinal blood vessels were segmented in a predefined circumpapillary region of interest. For each centerline, vessel tortuosity index (VTI), vessel inflection index (VII), and branching angle (VBA) were quantified, independently for arteries and veins. Additionally, we automatically quantified retinal amyloid count in the supero-temporal quadrant and its subregions: posterior pole (PP), proximal mid-periphery (PMP), and distal mid-periphery (DMP). All quantifications were done blinded to the subjects’ clinical characteristics. Linear regression models were used to assess the correlations between retinal vascular and amyloid parameters.

Results: 29 subjects (55% female, mean age 64±6 years) were included in the analysis: 11 had normal cognition, 16 mild cognitive impairment and 2 probable AD. Venous VTI was the only vascular parameter significantly different across levels of Clinical Dementia Rate scores and between cognitively normal and impaired. Venous VBA was a significant predictor of DMP amyloid count (p=0.03). Arterial VII significantly predicted PP amyloid count (p=0.02). VBA predicted Wechsler Adult Intelligence Scale Z-score (p=0.08). The combined VTI-PMP amyloid index significantly predicted Wechsler Memory Scale, California Verbal Learning Test and SF-36 mental component score Z-scores (p<0.05).

Conclusion: Retinal venous tortuosity discriminates across cognitive scores and in combination with PMP amyloid count may predict verbal memory and related quality-of-life scores.

Abstract P139: Efficacy and Utility of Resident-Run Telestroke Evaluations

Introduction: Exposure to telestroke in neurology residency is sparse despite its implementation in daily practice. Due to COVID-19, we increased our utilization of telestroke. Given this change in workflow, we investigated how residents utilize telestroke for “Code Brain” (CB) acute stroke evaluations and if expanding the use of telestroke in neurology residency programs is justified.

Methods: We retrospectively compared the number of CB evaluations, door to needle (DTN) times, door to decision (DTD) times, and NIHSS from March - June 2019 (in-person evaluations) against those in March - June 2020 (telestroke evaluations). We limited our study to resident-involved cases. Nighttime and weekend CBs are run by a neurology resident and are remotely supervised. Daytime CBs can be run by a resident, fellow, or attending. We assumed that nighttime CBs are resident-run and daytime evaluations are the stroke team’s evaluation. Statistical analysis was performed using R.

Results: There were a total of 217 CBs in March - June 2019 and 115 in March - June 2020. In 2019, there were 120 daytime and 97 nighttime CBs; in 2020 there were 62 and 53. The mean DTN for the day for 2019 and 2020 was 45.9 ± 23.2 and 48.4 ± 20.2 (P=0.08). The mean DTN during the night for 2019 and 2020 was 67.3 ± 53.7 and 53.8 ± 25.8 (P=0.64). The mean DTD during the day for 2019 and 2020 was 48.1 ± 41.0 and 44.9 ± 37.6 (P=0.25). The mean DTD during the night for 2019 and 2020 was 60.9 ± 51.1 and 65.8 ± 94.6 (P=0.68). Using a generalized linear model approach to correct for shift (day/night), age, NIHSS, we found no significant differences in DTN or DTD before and after implementing resident-run telestroke. Using Cohen’s approach (1988) we estimated a Type 2 error probability at 7%.

Discussion: Our findings show that resident-run telestroke CBs are comparable to CBs run by fellows and attendings as DTN and DTD were not significantly different between the CBs run by residents in-person or via telestroke. These metrics are also comparable for CBs in which a fellow or attending are supervising or running the CB. Implementing resident-run telestroke consultation showed no effect on DTN or DTD after accounting for patient age, NIHSS, or the time of day. These data should reassure programs seeking to grant telestroke privileges to trainees.

The future of neuroprotection in stroke

Investigators acknowledge the limitations of rodent or non-human primate stroke models, hundreds of putative neuroprotectants have been evaluated in preclinical models, but not one has entered the clinical realm. Initial studies focused on the neuron, but in recent years the focus has widened to also include other neural cells including astrocytes, pericytes and endothelial cells, which together form the neurovascular unit. Some new developments raise renewed hope for neuroprotection: the appearance of new compounds with multiple mechanisms of action, or the promulgation of new standards for a rigorous preclinical testing. At the bedside in the last 5 years, uric acid and nerinetide are the only compounds tested for clinical efficacy in randomised controlled trials (RCTs), where all patients had to receive reperfusion therapies, either intravenous thrombolysis and/or mechanical thrombectomy. In addition, otaplimastat, 3K3A-activated protein C (APC), intra-arterial verapamil and intra-arterial hypothermia were also assessed in combination with reperfusion therapy, but in RCTs that only included feasibility or safety outcomes. Some of these compounds yielded promising results which are discussed in this review. Altogether, a deeper knowledge of the mechanisms involved in the ischaemic death process at the neurovascular unit, an improved preselection and evaluation of drugs at the preclinical stage and the testing of putative neuroprotectants in enriched clinical studies of patients receiving reperfusion therapies, might prove more effective than in the past to reverse a dismal situation that has lasted already too long.

Stroke Treatment With PAR-1 Agents to Decrease Hemorrhagic Transformation

Ischemic stroke is the most widespread cause of disability and a leading cause of death in developed countries. To date, the most potent approved treatment for acute stroke is recanalization therapy with thrombolytic drugs such as tissue plasminogen activator (rt-PA or tPA) or endovascular mechanical thrombectomy. Although tPA and thrombectomy are widely available in the United States, it is currently estimated that only 10-20% of stroke patients get tPA treatment, in part due to restrictive selection criteria. Recently, however, tPA and thrombectomy selection criteria have loosened, potentially allowing more patients to qualify. The relatively low rate of treatment may also reflect the perceived risk of brain hemorrhage following treatment with tPA. In translational research and a single patient study, protease activated receptor 1 (PAR-1) targeted therapies given along with thrombolysis and thrombectomy appear to reduce hemorrhagic transformation after recanalization. Such adjuncts may likely enhance the availability of recanalization and encourage more physicians to use the recently expanded selection criteria for applying recanalization therapies. This narrative review discusses stroke therapies, the role of hemorrhagic transformation in producing poor outcomes, and presents the data suggesting that PAR-1 acting agents show promise for decreasing hemorrhagic transformation and improving outcomes.

Sectoral segmentation of retinal amyloid imaging in subjects with cognitive decline

INTRODUCTION

Despite advances in imaging retinal amyloidosis, a quantitative and topographical investigation of retinal amyloid beta burden in patients with cognitive decline has never been reported.

METHODS

We used the specific amyloid-binding fluorophore curcumin and laser ophthalmoscopy to assess retinal amyloid imaging (RAI) in 34 patients with cognitive decline. We automatically quantified retinal amyloid count (RAC) and area in the superotemporal retinal sub-regions and performed correlation analyses with cognitive and brain volumetric parameters.

RESULTS

RAC significantly and inversely correlated with hippocampal volume (HV; r = -0.39, P = .04). The proximal mid-periphery (PMP) RAC and RA areas were significantly greater in patients with Montreal Cognitive Assessment (MOCA) score < 26 (P = .01; Cohen d = 0.83 and 0.81, respectively). PMP showed significantly more RAC and area in subjects with amnestic mild cognitive impairment (MCI) and Alzheimer's disease (AD) compared to cognitively normal (P = .04; Cohen d = 0.83).

CONCLUSION

Quantitative RAI is a feasible technique and PMP RAC may predict HV. Future larger studies should determine RAI's potential as a biomarker of early AD.

Acute ophthalmic artery occlusion in a COVID-19 patient on apixaban

We report a case of ophthalmic artery occlusion (OAO) in a young patient with COVID-19 infection that was on therapeutic anticoagulation with apixaban for deep venous thrombosis (DVT). A 48-year-old man with obesity was hospitalized with a severe form of COVID-19 infection, complicated with acute respiratory failure, septic shock, dilated cardiomyopathy and fungemia. Despite treatment with prophylactic enoxaparin (initial D-Dimer 1.14 µg/ml FEU (normal < 0.05 µg/ml FEU), D-Dimer increased to above 20 µg/ml FEU and patient continued to spike high fevers. This prompted further investigations and upper and lower extremities DVTs were confirmed and managed with enoxaparin 1 mg/kg twice daily. D-dimer level decreased to 4.98 µg/ml FEU while on therapeutic anticoagulation. Three weeks later pending hospital discharge, the anticoagulation was switched to oral apixaban 10 mg twice daily. Patient developed acute severe right eye visual loss of no light perception and was diagnosed with incomplete OAO. D-Dimer was elevated at 2.13 µg/ml FEU. Stroke etiological work-up found no embolic sources, resolution of the dilated cardiomyopathy and negative antiphospholipid antibodies. Treatment was changed to enoxaparin and no thrombotic events were encountered to date. Ocular vascular complications have not yet been reported in COVID-19. Controversy exists on the best management algorithm for the hypercoagulable state associated to COVID-19 Either direct oral anticoagulants or low-molecular-weight-heparin are considered appropriate at discharge for patients with venous thromboembolism. The optimum regimen for ischemic stroke prevention and the significance of D-Dimer for anticoagulation monitoring in COVID-19 remain unclear.

Missing outcome data management in acute stroke trials testing iv thrombolytics. Is there risk of bias?

INTRODUCTION

Missing outcome data may undermine interpretation of randomised clinical trials by weakening power and limiting apparent effect size. We assessed bias and inefficiency of two imputation methods commonly used in stroke trials evaluating the efficacy of iv thrombolysis.

PATIENTS AND METHODS

We searched the virtual international stroke trials archive (VISTA)-acute for ischaemic stroke patients with 90-day modified Rankin scale as an outcome, and known thrombolysis status. We excluded any with missing 30-day modified Rankin scale. We planned two analyses; first, we calculated odds ratios for outcome in thrombolysed versus not thrombolysed from imputed-only data, (a) among patients with missing modified Rankin scale 90 and (b) among matched patients with intact data (using propensity score methods and relevant covariates). Imputation approaches were last observation carried forward (LOCF) or multiple imputation. Outcome comparisons used dichotomisation and shift analysis. Thereafter, we calculated whole-population odds ratios using LOCF and multiple imputation (also through dichotomisation and shift analysis); first with the original 1.5% missing outcome data, and then artificially increasing the burden (5%; 10%; 20%; 30%).

RESULTS

We considered 9657 patients from eight of the studies included in VISTA, 3034 (31%) thrombolysed. Missing data replacement by LOCF with analysis by dichotomisation gave the highest estimate of thrombolysis influence. Imputing while increasing the burden of missing data progressively raised the odds ratios estimates, though thresholds for overestimation were 10% for LOCF; 20% for multiple imputation.Discussion: Replacing missing outcome data tended to overestimate differences of thrombolysed versus non-thrombolysed patients, but had minimal impact below a 10% burden of missing data.Conclusion: In the specific context of acute stroke trials testing iv thrombolytics, replacing missing data by carrying forward the last observation tended to overestimate treatment odds ratios more than multiple imputation.

Assessing Cerebrovascular Hemodynamics Using Transcranial Doppler in Patients with Mechanical Circulatory Support Devices

BACKGROUND AND PURPOSE

Mechanical circulatory support (MCS) devices are commonly used in heart failure patients. These devices carry risk for presumably embolic and additionally hemorrhagic stroke. Alterations in blood flow play a key role in stroke pathophysiology, and we aimed to learn more about hemodynamic compromise. In this study, we used transcranial Doppler (TCD) ultrasound to define hemodynamics of commonly used nonpulsatile MCS devices, as well as pulsatile devices, with special attention to the total artificial heart (TAH).

METHODS

From 2/2013 through 12/2016, we prospectively enrolled patients with MCS who underwent TCD imaging. We analyzed TCD parameters, including peak systolic velocity, end-diastolic velocity, pulsatility indices (PIs), and number of high-intensity transient signals. Waveform morphologies were compared between various MCS devices.

RESULTS

We performed 132 TCD studies in 86 MCS patients. Waveforms in patients supported by venoarterial-extracorporeal membrane oxygenation demonstrated continuous flow without clear systolic peaks with an average (±SD) PI of .43 (±.2). PIs were low in patients with continuous-flow left ventricular assist devices with a mean PI of .32 (±.13). Impella patients had morphologically distinct pulsatile waveforms and a higher mean PI of .65 (±.24). In intra-arterial balloon pump patients, mean PI was 1.01 (±.16) and diastolic upstrokes were pronounced. In TAH patients, mean middle cerebral artery velocity of 79.69 (±32.33) cm/seconds and PI of .74 (±.14) approached normal values.

CONCLUSION

TCD can detect characteristic waveforms in patients supported by various MCS devices. These device-specific TCD patterns are recognizable and reproducible.

Abstract WP487: Retinal Vessel Tortuosity Correlates With White Matter Hyperintensities and Cerebral Microbleeds in Subjects With Cognitive Decline

Objective: Retinal microvasculature analysis is suitable to study cognitive disorders given retinal and brain vessels share similar properties. Using novel automated technologies, we aimed to investigate whether automatically-quantified retinal vascular changes from retinal fundus photographs predict brain imaging abnormalities in patients with cognitive impairment; and what specific retinal vascular parameters are more predictive of dementia.

Methods: In this cross-sectional study, 34 subjects with cognitive complaints underwent neuropsychometric cognitive testing, retinal fundus photography and brain MRI. Retinal vessel tortuosity index (VTI), inflection index (VII) and length (VL) were automatically computed. The number and volume of cerebral microbleeds (CMB) and white matter hyperintensities (WMHI) were measured using SPIN Software (SpinTech, Bingham Farms, MI). The diagnostic groups were compared for demographic, cognitive, retinal and brain imaging parameters using analysis of variance. The association between brain (intracranial volume (ICV), hippocampal volume (HV), lateral ventricle volume (LVV), WMHI and CMB (volume, number), Fazekas scores) and retinal vascular parameters were assessed by using multiple linear regression models.

Results: Nine subjects were cognitively normal (CN) and 25 cognitively impaired (CI) (22 with mild cognitive impairment and 3 with dementia). VTI was the only retinal parameter and HV and LVV were the brain parameters that were significantly different between CN and CI subjects (p=0.02). VTI correlated with VL (p=0.02, r=0.33) and branching angle (p=0.004, r=-0.45). The cognitive domains predicted by VTI were abstraction and orientation. VTI correlated with total intracranial volume (p=0.04, r=-0.12). A significant association was demonstrated for VII and WMHI volume (p=0.03, r=0.007), but not Fazekas score. VII and VTI significantly correlated with CMB volume (p=0.04 and 0.03, respectively).

Conclusion: Automatically-detected retinal vessel tortuosity indexes predict neuroimaging markers of microvascular disease and total intracranial volume in cognitively impaired individuals. Retinal imaging may be used to screen patients with cognitive disorders.

Abstract 31: The Frequency of Thrombectomy in Early and Late Post-Onset Time Windows Among EMS Transported Patients With Acute Ischemic Stroke

Introduction: With recent trials demonstrating benefit to thrombectomy up to 16 or 24 hours (h) from last known well time (LKWT), EMS systems must consider stroke center routing for patients with LKWT ≤24h. Increased transport times can strain resources and may be unnecessary if few patients receive the intended therapy. We sought to determine the frequency of thrombectomy by prehospital-determined LKWT (p-LKWT) in a large regional acute stroke care system.

Methods: In January 2018 Los Angeles (LA) County EMS initiated two-tiered routing within its regional system of 50 approved stroke center (ASC) serving 10 million persons. Patients with suspected stroke with p-LKWT ≤24h are routed to ASCs. Patients with potential LVOs (LA Motor Scale (LAMS) of 4 or 5) are routed directly to a designated thrombectomy-capable center (TSC or comprehensive stroke center (CSC)) if within 30 minutes; others are routed to the closest ASC. We abstracted adult EMS transports to a TSC or CSC from January 2018 to March 2019 with final diagnosis of AIS. We excluded transfers and patients without documented LKWT. We determined the frequency of thrombectomy by time intervals from p-LKWT to first medical contact (FMC).

Results: During the study period, 1317 AIS patients with p-LKWT ≤24h were transported to a TSC or CSC; 360 (27.1%) received endovascular thrombectomy. Patients were 47% male, median age 77 years (IQR 66-86), median NIHSS 11 (IQR 4-19), and median p-LKWT-to-FMC time interval 69 minutes (IQR 22-360). The table shows the frequency of thrombectomy by p-LKWT-FMC time intervals. Respectively, the ≤6h, >6 to ≤16h, and >16 to ≤24h windows accounted for 76.8%, 18.3%, and 4.9% of transports to thrombectomy-capable centers.

Conclusion: With two-tier routing in this regional stroke system, patients in the >6h post-onset window accounted for nearly one quarter of transports to TSCs and CSCs and 22% received thrombectomy. These findings support EMS stroke routing policies up to 24h post-onset.

Differential effects of hypothermia on neurovascular unit determine protective or toxic results: Toward optimized therapeutic hypothermia

Therapeutic hypothermia (TH) benefits survivors of cardiac arrest and neonatal hypoxic-ischemic injury and may benefit stroke patients. Large TH clinical trials, however, have shown mixed results. Given the substantial pre-clinical literature supporting TH, we explored possible mechanisms for clinical trial variability. Using a standard rodent stroke model (n = 20 per group), we found smaller infarctions after 2 h pre- or post-reperfusion TH compared to 4 h. To explore the mechanism of this discrepancy, we used primary cell cultures of rodent neurons, astrocytes, or endothelial cells subjected to oxygen-glucose deprivation (OGD). Then, cells were randomly assigned to 33℃, 35℃ or 37℃ for varying durations after varying delay times. Both 33 and 35℃ TH effectively preserved all cell types, although 33℃ was superior. Longer cooling durations overcame moderate delays to cooling initiation. In contrast, TH interfered with astrocyte paracrine protection of neurons in a temperature-dependent manner. These findings suggest that longer TH is needed to overcome delays to TH onset, but shorter TH durations may be superior to longer, perhaps due to suppression of astrocytic paracrine support of neurons during injury. We propose a scheme for optimizing TH after cerebral injury to stimulate further studies of cardiac arrest and stroke.

Neuron-generated thrombin induces a protective astrocyte response via protease activated receptors

Astrocytes protect neurons during cerebral injury through several postulated mechanisms. Recent therapeutic attention has focused on enhancing or augmenting the neuroprotective actions of astrocytes but in some instances astrocytes can assume a neurotoxic phenotype. The signaling mechanisms that drive astrocytes toward a protective versus toxic phenotype are not fully known but cell-cell signaling via proteases acting on cell-specific receptors underlies critical mechanistic steps in neurodevelopment and disease. The protease activated receptor (PAR), resides in multiple brain cell types, and most PARs are found on astrocytes. We asked whether neuron-generated thrombin constituted an important astrocyte activation signal because our previous studies have shown that neurons contain prothrombin gene and transcribed protein. We used neuron and astrocyte mono-cell cultures exposed to oxygen-glucose deprivation and a model of middle cerebral artery occlusion. We found that ischemic neurons secrete thrombin into culture media, which leads to astrocyte activation; such astrocyte activation can be reproduced with low doses of thrombin. Media from prothrombin-deficient neurons failed to activate astrocytes and adding thrombin to such media restored activation. Astrocytes lacking PAR1 did not respond to neuron-generated thrombin. Induced astrocyte activation was antagonized dose-dependently with thrombin inhibitors or PAR1 antagonists. Ischemia-induced astrocyte activation in vivo was inhibited after neuronal prothrombin knockout, resulting in larger strokes. Restoring prothrombin to neurons with a lentiviral gene vector restored astrocyte activation and reduced stroke damage. We conclude that neuron-generated thrombin, released during ischemia, acts via PAR1 and may cause astrocyte activation and paracrine neuroprotection.

Neuroprotection and vasculoprotection using genetically targeted protease-ligands

Thrombin and activated protein C (APC) are known coagulation factors that exhibit profound effects in brain by acting on the protease activated receptor (PAR). The wild type (WT) proteases appear to impact cell survival powerfully, and therapeutic forms of APC are under development. Engineered recombinant thrombin or APC were designed to separate their procoagulant or anticoagulant effects from their cytoprotective properties. We measured vascular disruption and neuronal degeneration after a standard rodent filament stroke model. For comparison to a robust anticoagulant, we used a GpIIb/IIIa inhibitor, GR144053. During 2 h MCAo both WT murine APC and its mutant, 5A-APC, significantly decreased neuronal death 30 min after reperfusion. During 4 h MCAo, only 5A-APC significantly protected neurons but both WT-APC and 5A-APC exacerbated vascular disruption during 4 h MCAo. Human APC mutants appeared to reduce 24 h neuronal injury significantly when given after 2 h delay after MCAo. In contrast, 24 h vascular damage was worsened by high doses of WT and mutant APCs, although only statistically significantly for high dose 3K3A-APC. Mutated thrombin worsened vascular damage significantly without affecting neuron damage. GR144053 failed to ameliorate vascular disruption or neuronal injury despite significant anticoagulation. Differential effects on neurons and the vasculature were demonstrated using wild-type and mutated proteases. The mutants murine 3K3A-APC and 5A-APC protected neurons in this rodent model but in high doses worsened vascular leakage. Cytoactive effects of plasma proteases may be separated from their coagulation effects. Further studies should explore impact of dose and timing on cytoactive and vasculoactive properties of these drugs.

Acute neuropathological consequences of short-term mechanical ventilation in wild-type and Alzheimer's disease mice

Background

Mechanical ventilation is strongly associated with cognitive decline after critical illness. This finding is particularly evident among older individuals who have pre-existing cognitive impairment, most commonly characterized by varying degrees of cerebral amyloid-β accumulation, neuroinflammation, and blood-brain barrier dysfunction. We sought to test the hypothesis that short-term mechanical ventilation contributes to the neuropathology of cognitive impairment by (i) increasing cerebral amyloid-β accumulation in mice with pre-existing Alzheimer’s disease pathology, (ii) increasing neurologic and systemic inflammation in wild-type mice and mice with pre-existing Alzheimer’s disease pathology, and (iii) increasing hippocampal blood-brain barrier permeability in wild-type mice and mice with pre-existing Alzheimer’s disease pathology.

Methods

We subjected double transgenic Alzheimer’s disease (APP/PSEN1) and wild-type mice to mechanical ventilation for 4 h and compared to non-mechanically ventilated Alzheimer’s disease model and wild-type mice. Cerebral soluble/insoluble amyloid-β_1–40/amyloid-β_1–42 and neurological and systemic markers of inflammation were quantified. Hippocampal blood-brain barrier permeability was quantified using a novel methodology that enabled assessment of small and large molecule permeability across the blood-brain barrier.

Results

Mechanical ventilation resulted in (i) a significant increase in cerebral soluble amyloid-β_1–40 (p = 0.007) and (ii) significant increases in neuroinflammatory cytokines in both wild-type and Alzheimer’s disease mice which, in most cases, were not reflected in the plasma. There were (i) direct correlations between polymorphonuclear cells in the bronchoalveolar fluid and cerebral soluble amyloid-β_1–40 (p = 0.0033), and several Alzheimer’s disease-relevant neuroinflammatory biomarkers including cerebral TNF-α and IL-6; (iii) significant decreases in blood-brain barrier permeability in mechanically ventilated Alzheimer’s disease mice and a trend towards increased blood-brain barrier permeability in mechanically ventilated wild-type mice.

Conclusions

These results provide the first evidence that short-term mechanical ventilation independently promotes the neuropathology of Alzheimer’s disease in subjects with and without pre-existing cerebral Alzheimer’s disease pathology. Future studies are needed to further clarify the specific mechanisms by which this occurs and to develop neuroprotective mechanical ventilation strategies that mitigate the risk of cognitive decline after critical illness.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2356-2) contains supplementary material, which is available to authorized users.

Paradoxical cerebrovascular hemodynamic changes with nicardipine

OBJECTIVE

Intravenous nicardipine is commonly used for blood pressure reduction in patients with acute stroke. However, few studies have described its effects on cerebrovascular hemodynamics as measured by transcranial Doppler (TCD) waveform analysis and pulsatility index (PI). In this study, the authors report examples of a consistent but paradoxical finding associated with nicardipine that suggests intracranial vasoconstriction, contrary to what is expected from a vasodilator.

METHODS

The data presented are from a convenience sample of patients who underwent TCD monitoring before, after, or during nicardipine administration. In each case, TCD waveform morphologies and PIs were compared.

RESULTS

The TCD waveforms during nicardipine infusion are characterized by a prominent systolic peak and dicrotic notch. Systolic deceleration was more pronounced and PIs were significantly elevated in patients who were on nicardipine (p < 0.001). This finding was not evident when patients were not on nicardipine.

CONCLUSIONS

This study provides the first evidence of paradoxical intracranial vasoconstriction associated with intravenous nicardipine. In the authors' experience, this finding is consistently encountered in the vast majority of patients who are treated with intravenous nicardipine, and is contradictory to what is expected from a vasodilator. Future studies are needed to confirm this finding in larger populations and diverse clinical settings and to examine mechanisms that explain this phenomenon.

Abstract TP260: A Novel Neurogenic-Stem Cell Stimulating Curcumin Analog to Treat Acute Ischemic Stroke

While nerve cells rapidly die in stroke, and patients do initiate a neurogenic response to replace these cells, there has been no attempt to develop pleiotropic cytoprotective compounds to further promote neurogenesis in stroke patients, and there are no neurogenic or cytoprotective drugs approved by the FDA. In this study, we focused on the parent compound J-147, a curcumin derivative that is a 5-LOX inhibitor, and has potent neuroprotective and neurogenic activities. J-147 rescues HT22 cells from iodoacetic acid challenge (EC 50 50 nM), and oxytosis (EC 50 115 nM). J-147 is neuroprotective against glutamate excitotoxcity in E18 cortical neuron culture (EC 50 27 nM), and prevents cell death in an embryonic cortical cell trophic factor withdrawal assay (EC 50 25 nM). J-147 can rescue a clone of the hippocampal nerve cell line HT22 expressing TrkB, from serum starvation under conditions where the cells can be protected by BDNF (EC 50 50 nM). In mice, J-147 is neurogenic and can stimulate cell division in germinal regions of the brain (increase BrdU + DCX + labeled cells), enhances endogenous neurotrophic factors and energy metabolism. With this basis, we tested J-147 in 2 translational stroke models. First, using a rodent intraluminal suture model, in combination with a quantal analysis method to determine the effect of increasing ischemia duration (5-90 minutes) on behavioral deficits, IV J-147 treatment (10 mg/kg) administered 5 minutes following the end of occlusion (5-90 minutes), significantly (P=0.045) reduced stroke-induced behavioral deficits and increased the P 50 value to 36.37 ± 1.72 (n=19) minutes from P 50 = 20.1 ± 4.07 minutes (n=19) for the control group. J-147 also reduced infarct volume following IV administration (p<0.05). Second, using the standardized rabbit small clot embolic stroke model, IV J-147 treatment (10mg/kg) administered 1 hour post-embolization increased the P 50 value (behavior) to 1.88 ± 0.10 mg (n=20) compared to P 50 = 1.07 ± 0.07 (n=19) for control(p<0.05). Additional studies showed that J-147 was not mitogenic, or cytotoxic using the CeeTox assay (Raking 90μM) and had a good IV PK profile in rabbits/rats (t 1/2 5.89-8.56 hours). These data support the development of J-147 and neurogenic analogs as a novel class of drug to treat stroke.

Abstract WP127: Effects of EDAS Revascularization and Intensive Medical Management on the Cognitive Function of Patients With Intracranial Atherosclerosis

Introduction: Cognitive decline after transient ischemic attacks (TIA) or stroke is common. Evaluation with the Montreal Cognitive Assessment (MoCA) tool has shown a decrease in cognitive scores in more than 30% of patients at 1 year. We hypothesize that indirect revascularization with EDAS plus intensive medical management (IMM) would decrease the rate of decline.

Methods: This is a prospective study of EDAS plus IMM in symptomatic patients with intracranial arterial stenosis of more than 70%. Patients had MoCA evaluations at baseline, 1 month, 6 months, and 12 months after EDAS. Differences in MoCA at baseline and follow-up were compared using mixed model repeated measures ANOVA.

Results: Thirty-one patients with no aphasia or neglect were included. Mean age was 48.3 +/- 16.6 years. Twenty-one were females (70%). The mean MoCA scores at baseline and 12-months were 23.6 +/- 4.3 and 25.5 +/- 4.1, respectively. MoCA ≥ 1 improvement was seen in 78.9% at 12 months. However, differences in MoCA scores at these time points did not reach statistical significance (p= 0.49, Fig. 1). Only 9% of patients had a decline of ≥2 MoCA points at 12 months. These results are comparable to the twelve month MoCA data from the SAMMPRIS trial, which showed a mean MoCA for IMM of 25.4 +/- 3.73 and for percutaneous angioplasty and stenting (PTAS) of 25.6 +/- 3.89. The rate of decline of MoCA scores after EDAS plus IMM was significantly less than the reported natural history after TIA or strokes outside the SAMMPRIS trial (9% vs. 30%, p=0.03).

Conclusion: Compared to historical data, the decline in MoCA scores after TIA and stroke was lower in patients treated with EDAS plus maximum medical therapy and has similar effects to those reported in the SAMMPRIS IMM and PTAS groups.

Abstract TP213: Retinal Microvascular Abnormalities as Markers of Cerebrovascular Disease: A Meta-Analysis

Introduction: Despite the recognized linkage between retinal microvascular abnormalities and cerebrovascular ischemic diseases (CVD), the retinal findings’ standardization and the degree of association remain unclear. We aimed to investigate the quantitative association between various retinal microvascular signs and CVD.

Hypothesis: retinal microvascular abnormalities best predictive of CVD could be identified by synthesizing estimates of CVD risk from population-based studies.

Methods: We followed MOOSE guidelines and systematically searched 6 databases through September 2016 for studies evaluating the association between retinal microvascular abnormalities and white matter hyperintense lesions (WMHI), lacunar infarcts (LI), and cerebral infarctions (CI). Adjusted and unadjusted odds ratios (ORs) and confidence intervals were pooled into the analyses using the DerSimonian and Laird random effects model. Study quality and dissemination biases were assessed and integrated.

Results: Thirty-four prospective studies encompassing 84,144 patients were eligible for meta-analysis. After adjustment for vascular risk factors, focal arteriolar narrowing was associated with WMHI (OR, 1.24 [1.01-1.79]), LI (OR, 1.77 [1.14-2.74]), and CI (OR, 1.75 [1.14-2.69]). Venular dilation was significantly associated with LI (OR, 1.46 [1.10-1.93]), whereas retinal hemorrhage was associated with WMHI (OR, 2.23 [1.34-3.70]). Arteriovenous nicking was associated with WMHI (OR, 1.51 [1.22-1.88]) and LI (OR, 1.70 [1.05-2.76]). Any retinopathy exhibited significant association with WMHI, LI, and CI. Heterogeneity was significant ( I 2 >50%) for all syntheses except retinal hemorrhages and WMHI, retinopathy and CI ( I 2 =0.0%) and respectively LI ( I 2 =45.80%).

Conclusions: Retinal hemorrhages were most highly associated with WMHI. Focal arteriolar narrowing and retinopathy were associated with WMHI, LI, and CI. Our findings may assist in the development of a noninvasive retinal microvascular tool for routine use in CVD research and clinical practice.