Risk of Hemorrhagic Transformation with Early Use of Direct Oral Anticoagulants after Acute Ischemic Stroke: A Pooled Analysis of Prospective Studies and Randomized Trials

INTRODUCTION

Precise risk of hemorrhagic transformation (HT) in acute ischemic stroke (AIS) remains unknown, leading to delays in anticoagulation initiation for secondary stroke prevention. We sought to assess the rate of HT associated with direct oral anticoagulant (DOAC) initiation within and beyond 48 hours post-AIS.

METHODS

A pooled analysis of DOAC initiation within 14 days of AIS or transient ischemic attack (TIA) was conducted with 6 studies (4 prospective open label treatment, blinded outcome studies and 2 randomized trials; NCT02295826 and NCT02283294). The primary endpoint was incident radiographic HT on follow-up imaging (day 7-30). Secondary endpoints included symptomatic HT, new parenchymal hemorrhage, recurrent ischemic events, extracranial hemorrhage, study-period mortality, and follow-up modified Rankin Scale score. The results were reported as odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI).

RESULTS

We evaluated 509 patients; median infarct volume was 1.5 (0.1-7.8) ml, and median National Institutes of Health Stroke Scale was 2 (0-3). Incident radiographic HT was seen on follow-up scan in 34 (6.8%) patients. DOAC initiation within 48 hours from index event was not associated with incident HT (adjusted OR 0.67, [0.30 - 1.50] P=0.32). No patients developed symptomatic HT. Conversely, 31 (6.1%) patients developed recurrent ischemic events, 64% of which occurred within 14 days. Initiating a DOAC within 48 hours of onset was associated with similar recurrent ischemic event rates compared to those in which treatment was delayed (HR 0.42, [0.17 - 1.008] P=0.052). In contrast to HT, recurrent ischemic events were associated with poor functional outcomes (OR=6.8, [2.84 - 16.24], p<0.001).

CONCLUSIONS

In this pooled analysis, initiation of DOAC within 48 hours post-stroke was not associated with increased incident risk of HT, and none developed symptomatic HT. The analysis was underpowered to determine the effect of early DOAC use upon recurrent ischemic events.

Three-month functional outcomes following endovascular thrombectomy during the first wave of the COVID-19 pandemic: a Canadian single-center cohort study

BACKGROUND

The COVID-19 pandemic has disrupted acute stroke care logistics, including delays in hyperacute management and decreased monitoring following endovascular therapy (EVT). We aimed to assess the impact of the pandemic on 90-day functional outcome among patients treated with EVT.

METHODS

This is an observational cohort study including all patients evaluated for an acute stroke between March 30, 2020 and September 30, 2020 (pandemic cohort) and 2019 (reference cohort) in a high-volume Canadian academic stroke center. We collected baseline characteristics, acute reperfusion treatment and management metrics. For EVT-treated patients, we assessed the modified Rankin score (mRS) at 90 days. We evaluated the impact of the pandemic on a 90-day favourable functional status (defined as mRS 0-2) and death using multivariable logistic regressions.

RESULTS

Among 383 and 339 patients included in the pandemic and reference cohorts, baseline characteristics were similar. Delays from symptom onset to evaluation and in-house treatment were longer during the early first wave, but returned to reference values in the subsequent months. Among the 127 and 136 EVT-treated patients in each respective cohort, favourable 90-day outcome occurred in 53/99 (53%) vs 52/109 (48%, p=0.40), whereas 22/99 (22%) and 28/109 (26%, p=0.56) patients died. In multivariable regressions, the pandemic period was not associated with 90-day favourable functional status (aOR 1.27, 95% CI 0.60 to 2.56) or death (aOR 0.74, 95% CI 0.33 to 1.63).

CONCLUSION

In this single-center cohort study conducted in a Canadian pandemic epicenter, the first 6 months of the COVID-19 pandemic did not impact 90-day functional outcomes or death among EVT-treated patients.

Antimicrobial activity of harzianic acid against Staphylococcus pseudintermedius

The emerging concern about the increase of antibiotic resistance has encouraged research efforts to develop effective alternatives to counteract bacterial infections. Herein, we studied a new perspective to therapeutic treatment against Staphylococcus pseudintermedius, an opportunistic pathogen documented as the major cause of skin, ear, and post-operative bacterial infections in dogs and cats. Antimicrobial activity of secondary metabolites produced by selected microbial strains belonging to Trichoderma, Talaromyces, Clonostachys and Coniothyrium fungal genera has been tested against S. pseudintermedius. Several extracts, particularly those obtained from Trichoderma harzianum E45 and ET45, showed a significant antimicrobial activity towards S. pseudintermedius methicillin-resistant (MRSP) and methicillin-susceptible (MSSP) strains. Bioassay-guided fractionation of E45 and ET45 extracts allowed to isolate harzianic acid as the major compound responsible for biological activities (e.g. antimicrobial, antibiofilm formation and biofilm disaggregation).

Exophthalmos following mechanical thrombectomy for anterior circulation stroke: A retrospective study and review of literature

BACKGROUND

Anecdotal cases of exophthalmos after acute mechanical thrombectomy have been described. We sought to estimate the incidence in a large cohort of patients with acute anterior circulation stroke treated with mechanical thrombectomy. Secondarily, we aimed to evaluate the underlying mechanism and to differentiate it on imaging from other pathology with similar clinical orbital features.

METHODS

Between November 2016 and November 2018, we performed a retrospective single-center study of 250 patients who underwent anterior circulation mechanical thrombectomy. Development of exophthalmos was independently evaluated by two readers on preprocedure and 24-h postprocedure non-contrast cerebral CT.

RESULTS

In the mechanical thrombectomy cohort, six individuals (2.4%) developed interval ipsilateral exophthalmos at 24 h. Of these, at least two patients developed clinical symptoms. There was almost perfect agreement between assessments of the two readers (Cohen's kappa = 0.907 (95% confidence interval: 0.726, 1.000)). In two patients, there was delayed ophthalmic artery filling on digital subtraction angiography. None of the patients had features of a direct carotid-cavernous fistula.

CONCLUSIONS

Exophthalmos is not uncommon after mechanical thrombectomy (2.4%). The underlying mechanism is difficult to confirm, but it is most likely due to orbital ischemia from hypoperfusion or distal emboli.

Fractional Quantum Hall Effect in Weyl Semimetals

Weyl semimetal may be thought of as a gapless topological phase protected by the chiral anomaly, where the symmetries involved in the anomaly are the U(1) charge conservation and the crystal translational symmetry. The absence of a band gap in a weakly interacting Weyl semimetal is mandated by the electronic structure topology and is guaranteed as long as the symmetries and the anomaly are intact. The nontrivial topology also manifests in the Fermi arc surface states and topological response, in particular taking the form of an anomalous Hall effect in magnetic Weyl semimetals, whose magnitude is only determined by the location of the Weyl nodes in the Brillouin zone. Here we consider the situation when the interactions are not weak and ask whether it is possible to open a gap in a magnetic Weyl semimetal while preserving its nontrivial electronic structure topology along with the translational and the charge conservation symmetries. Surprisingly, the answer turns out to be yes. The resulting topologically ordered state provides a nontrivial realization of the fractional quantum Hall effect in three spatial dimensions in the absence of an external magnetic field, which cannot be viewed as a stack of two dimensional states. Our state contains loop excitations with nontrivial braiding statistics when linked with lattice dislocations.

A randomized pragmatic care trial on endovascular acute stroke interventions (EASI): criticisms, responses, and ethics of integrating research and clinical care

BACKGROUND

The Endovascular Acute Stroke Intervention (EASI) trial was conceived as a pragmatic care trial, designed to integrate trial methods with clinical practice. Reporting the EASI experience was met with objections and criticisms during peer review concerning both scientific and ethical issues. Our goal is to discuss these criticisms in order to promote the pragmatic approach of care trials in outcome-based medical care.

METHODS

The comments and criticisms of 11 reviewers from 5 journals were collected and analyzed. The EASI protocol was also compared to the protocols of seven thrombectomy trials using the pragmatic-explanatory continuum indicator summary (PRECIS).

RESULTS

Main criticisms of EASI concerned selection criteria that were judged to be too vague and too inclusive, brain and vascular imaging methods that were not sufficiently prescribed by protocol, lack of blinding of outcome assessment, and lack of power. EASI was at the pragmatic end of the spectrum of thrombectomy trials.

CONCLUSION

The pragmatic care trial methodology is not currently well-established. More work needs to be done to integrate scientific methods and ethical care in the best medical interest of current patients.

Trichoderma-Based Biostimulants Modulate Rhizosphere Microbial Populations and Improve N Uptake Efficiency, Yield, and Nutritional Quality of Leafy Vegetables

Microbial inoculants such as Trichoderma-based products are receiving great interest among researchers and agricultural producers for their potential to improve crop productivity, nutritional quality as well as resistance to plant pathogens/pests and numerous environmental stresses. Two greenhouse experiments were conducted to assess the effects of Trichoderma-based biostimulants under suboptimal, optimal and supraoptimal levels of nitrogen (N) fertilization in two leafy vegetables: Iceberg lettuce (Lactuca sativa L.) and rocket (Eruca sativa Mill.). The yield, nutritional characteristics, N uptake and mineral composition were analyzed for each vegetable crop after inoculation with Trichoderma strains T. virens (GV41) or T. harzianum (T22), and results were compared to non-inoculated plants. In addition, the effect of the Trichoderma-based biostimulants on microbes associated with the rhizosphere in terms of prokaryotic and eukaryotic composition and concentration using DGGE was also evaluated. Trichoderma-based biostimulants, in particular GV41, positively increased lettuce and rocket yield in the unfertilized plots. The highest marketable lettuce fresh yield was recorded with either of the biostimulant inoculations when plants were supplied with optimal levels of N. The inoculation of rocket with GV41, and to a lesser degree with T22, elicited an increase in total ascorbic acid under both optimal and high N conditions. T. virens GV41 increased N-use efficiency of lettuce, and favored the uptake of native N present in the soil of both lettuce and rocket. The positive effect of biostimulants on nutrient uptake and crop growth was species-dependent, being more marked with lettuce. The best biostimulation effects from the Trichoderma treatments were observed in both crops when grown under low N availability. The Trichoderma inoculation strongly influenced the composition of eukaryotic populations in the rhizosphere, in particularly exerting different effects with low N levels in comparison to the N fertilized plots. Overall, inoculations with Trichoderma may be considered as a viable strategy to manage the nutrient content of leafy horticulture crops cultivated in low fertility soils, and assist vegetable growers in reducing the use of synthetic fertilizers, developing sustainable management practices to optimize N use efficiency.

Abstract WMP9: Real-World Outcomes of Patients Presenting with Acute Ischemic Stroke >6 Hours Since Symptom Onset Treated With Endovascular Therapy

Introduction: Endovascular therapy(EVT) is proven effective for patients with acute ischemic stroke with proximal vessel occlusion, treated within 6 hours since symptom onset. However, up to 30% of stroke patients wake up with their symptoms (“wake-up stroke” (WUS)) or have an unknown time of onset. Canadian guidelines suggest that EVT may also be effective up to 12 hours after onset and yet-to-be published data from the DAWN trial also suggest a strong benefit of EVT for these patients if selected by perfusion imaging. We aimed to examine the real-world effectiveness of EVT in late-presenting stroke patients selected for EVT with a simple non-contrast CT (NCCT) and simple phase CT angiogram (CTA).

Methods: We analyzed a prospectively collected registry of epidemiological, clinical and imaging data of patients treated for acute ischemic stroke ≥6 hours since symptom onset or WUS in a tertiary stroke center (Hôpital Notre-Dame, Montréal) between 2016 and 2017. Eligibility for EVT was based on a combination of disabling neurological deficit, a NCCT with salvageable brain tissue (ASPECTS >5), and presence of a LVO on CTA.

Results: Over a 16-month period, a total of 366 patients were treated with IV thrombolysis and/or EVT. Of these, 46 had WUS or presented ≥ 6 hours since symptom onset and received EVT. Median age was 70, median baseline mRS score 1, median NIHSS at arrival 17 and median ASPECTS 9. Good collaterals on CTA were noted in 63%(29) of patients. 5 patients had posterior circulation stroke with basilar occlusion. Median time from last time seen normal to admission was 9h17(IQR, 6h44-12h46). 31 (67.4%) NCCTs were done at a referent center and not repeated locally to avoid treatment delays. At 3-month follow-up, functional autonomy(mRS ≤ 2) was found in 15 (32.6%) patients while 15 (32,6%) died (mRS=6). Symptomatic hemorrhagic transformation occurred in 3(6.5%) patients.

Conclusions: In a real-world setting, EVT is feasible in late-presenting stroke patients selected by NCCT and yields favorable outcomes similar to those seen in the more pragmatic EVT trials.

Abstract WP339: Arterial Spin Labelling Cerebral Perfusion Measurements Demonstrate Normal Blood Flow in Subacute Intracerebral Hemorrhage Patients

Introduction: Perihematomal hypoperfusion in acute intracerebral hemorrhage (ICH) has been demonstrated using CT perfusion. Although blood pressure (BP) reduction does not appear to impact perihematomal Cerebral Blood Flow (CBF), measurements using contrast are limited to a single time point. It has also been shown that up to 41% of ICH patients develop subacute diffusion-weighted imaging (DWI) lesions on MRI. Arterial Spin Labelling (ASL) is an magnetic resonance imaging (MRI) technique that allows measurement of CBF without a contrast agent, making it suitable for serial measurements. We assessed CBF in ICH patients using ASL and tested the hypothesis that perihematoma perfusion is related to BP.

Methods: Patients with CT scan confirmed ICH were prospectively recruited within 6 hours of symptom onset. Acute systolic BP (SBP) targets were randomly assigned as part of an ongoing trial. The SBP target remained blinded for this analysis. Patients were assessed with ASL at 48 hours post ICH. The perihematoma region was defined using co-registered susceptibility weighted images to delineate the hematoma border. Relative CBF (rCBF) was calculated as a ratio of the ipsilateral to contralateral ASL measurements.

Results: Perfusion was measured in 6 ICH patients, none of whom had DWI lesions, 55.38 (43.72, 59.75) hours after onset. Median 48 hour hematoma volume was 23.40 (18.10, 99.90) ml. Mean±SD SBP at 48 hours was 140.20 ± 10.64 mmHg. Mean perihematomal rCBF was 0.95±0.37. Mean hemispheric rCBF was 0.95 ± 0.17. Perihematomal and hemispheric CBF was not lower in the side of the hematoma ( p >0.583). Hematoma size was unrelated to rCBF (perihematomal R=0.039, 95% CI [-0.880, 0.959], p =0.682; hemispheric R=0.00, 95% CI [-0.005, 0.006], p =0.932). Systolic BP at the time of the scan, difference between baseline SBP and SBP at the time of the scan, and time spent with SBP <140 mmHg were all not associated with perihematomal or hemispheric rCBF ( p >0.170).

Conclusion: It is feasible to measure perihematoma and hemispheric perfusion in ICH patients using ASL, which may be useful for serial CBF assessment, particularly in patients with MRI evidence of ischemia.

Abstract WMP104: Sub-Acute Diffusion-Weighted MRI Lesions in Acute Intracerebral Hemorrhage Patients are Unrelated to Blood Pressure

Introduction: Diffusion-Weighted magnetic resonance imaging (DWI) studies have demonstrated sub-acute ischemic lesions in up to 41% of patients with intracerebral hemorrhage (ICH). Retrospective studies indicated an association with acute blood pressure (BP) reduction. We conducted a prospective study of DWI lesion incidence in ICH patients.

Methods: Patients with computed tomography (CT) scan confirmed ICH were prospectively recruited within 6 hours of symptom onset. Acute systolic BP (SBP) targets were randomly assigned as part of an ongoing trial. The SBP target remained blinded for this analysis. Patients were assessed with serial DWI at 48 hours.

Results: Eighty-three patients (48.2% male, mean±SD age 71.9±13.4) were enrolled. MRI was obtained in 42 patients. (11 patients were medically unstable, 11 refused consent, 19 died or were treated palliatively prior to the first MRI). Median (IQR) acute hematoma volume of the patients undergoing magnetic resonance imaging was 14.11 (4.40, 38.06) ml. Median baseline NIHSS score was 12.50 (9, 20). Median (IQR) 48 hour hematoma volume was 23.30 (9.10, 65.30) ml. DWI lesions were present in 13 (31%) of patients at 48 hours (median time to scan 54.22 (39.83, 65.5) hours). Mean SBP at 48 hours in patients with lesions (154.55±27.02 mmHg) was similar to those without (149.04±27.02; p = 0.514). Systolic BP at the time of the MRI was not a predictor of ischemic lesion development at 48 hours (OR=1.015, [0.972, 1.059], p =0.507), nor was the change in BP between baseline and the scan (OR=0.994, [0.962, 1.027], p =0.716). The only predictor of 48 hour DWI incidence was hematoma volume at 48 hours (OR= 1.025, 95% CI [1.001, 1.050], p =0.044).

Discussion: When enrolled prospectively within 6 hours of onset, DWI was obtained in approximately half of all ICH patients. This selection bias may be relevant to the results of both retrospective and prospective DWI studies. This study demonstrated no evidence of a relationship between actual BP achieved and DWI incidence after ICH.

Canadian stroke best practice recommendations: Secondary prevention of stroke, sixth edition practice guidelines, update 2017

The 2017 update of The Canadian Stroke Best Practice Recommendations for the Secondary Prevention of Stroke is a collection of current evidence-based recommendations intended for use by clinicians across a wide range of settings. The goal is to provide guidance for the prevention of ischemic stroke recurrence through the identification and management of modifiable vascular risk factors. Recommendations include those related to diagnostic testing, diet and lifestyle, smoking, hypertension, hyperlipidemia, diabetes, antiplatelet and anticoagulant therapies, carotid artery disease, atrial fibrillation, and other cardiac conditions. Notable changes in this sixth edition include the development of core elements for delivering secondary stroke prevention services, the addition of a section on cervical artery dissection, new recommendations regarding the management of patent foramen ovale, and the removal of the recommendations on management of sleep apnea. The Canadian Stroke Best Practice Recommendations include a range of supporting materials such as implementation resources to facilitate the adoption of evidence to practice, and related performance measures to enable monitoring of uptake and effectiveness of the recommendations. The guidelines further emphasize the need for a systems approach to stroke care, involving an interprofessional team, with access to specialists regardless of patient location, and the need to overcome geographic barriers to ensure equity in access within a universal health care system.

Dabigatran following acute transient ischemic attack and minor stroke II (DATAS II)

Rationale

Patients with transient ischemic attack or minor stroke are at high risk of early recurrent cerebrovascular events. Anticoagulation with heparin or warfarin acutely after ischemic stroke is at least as efficacious as aspirin for preventing recurrent events but is associated with an increased risk of clinical worsening due to hemorrhagic transformation.

Aim and hypothesis

We aim to demonstrate the safety of early anticoagulation with dabigatran, an oral direct thrombin inhibitor, in acute cerebrovascular syndrome patients. The primary hypothesis is that symptomatic hemorrhagic transformation rates in dabigatran and aspirin-treated patients will be similar.

Sample size estimates

At least 136 participants in two groups required to demonstrate an absolute between-group difference in the rate of hemorrhagic transformation of 5.6% with 80% power, assuming alpha = 5%.

Methods and design

A randomized, multicenter open-label clinical trial (NCT02295826). Three-hundred participants with a transient ischemic attack/ischemic stroke (National Institutes of Health Stroke Scale ≤ 9) will undergo magnetic resonance imaging within 72 h of symptom onset and will be randomized to aspirin 81 mg daily or dabigatran 150 mg twice daily for 30 days. Participants undergo repeat magnetic resonance imaging at 30 days and clinical assessment to 90 days.

Study outcomes

The primary outcome is the symptomatic hemorrhagic transformation rate. Secondary outcomes include recurrent stroke and new ischemic lesions on repeat magnetic resonance imaging.

Discussion

This study will determine the safety of early anticoagulation with dabigatran in patients with acute transient ischemic attack/ischemic stroke and will inform the design of a phase III randomized trial aimed at demonstrating reduced recurrent early ischemic events after acute transient ischemic attack/stroke.

The intracerebral hemorrhage acutely decreasing arterial pressure trial II (ICH ADAPT II) protocol

Background

Aggressively lowering blood pressure (BP) in acute intracerebral hemorrhage (ICH) may improve outcome. Although there is no evidence that BP reduction changes cerebral blood flow, retrospective magnetic resonance imaging (MRI) studies have demonstrated sub-acute ischemic lesions in ICH patients. The primary aim of this study is to assess ischemic lesion development in patients randomized to two different BP treatment strategies. We hypothesize aggressive BP reduction is not associated with ischemic injury after ICH.

Methods

The Intracerebral Hemorrhage Acutely Decreasing Blood Pressure Trial II (ICH ADAPT II) is a phase II multi-centre randomized open-label, blinded-endpoint trial. Acute ICH patients (N = 270) are randomized to a systolic blood pressure (SBP) target of <140 or <180 mmHg. Acute ICH patients within 6 h of onset and two SBP measurements ≥140 mmHg recorded >2 mins apart qualify. SBP is managed with a pre-defined treatment protocol. Patients undergo MRI at 48 h, Days 7 and 30, with clinical assessment at Day 30 and 90. The primary outcome is diffusion weighted imaging (DWI) lesion frequency at 48 h. Secondary outcomes include cumulative DWI lesion rate frequency within 30 days, absolute hematoma growth, prediction of DWI lesion incidence, 30-day mortality rates, day 90 functional outcome, and cognitive status.

Discussion

This trial will assess the impact of hypertensive therapies on physiological markers of ischemic injury. The findings of this study will provide evidence for the link, or lack thereof, between BP reduction and ischemic injury in ICH patients.

Trial registration

This study is registered with clinicaltrials.gov  (NCT02281838, first received October 29, 2014).

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0884-4) contains supplementary material, which is available to authorized users.

Giant reed growth and effects on soil biological fertility in assisted phytoremediation of an industrial polluted soil

Phytoremediation is a cost-effective "green technology" that uses plants to improve the soil properties of polluted sites, preventing the dispersion of pollutants and reducing the mobility of potentially toxic elements (PTEs) through their adsorption and accumulation by roots or precipitation within the root zone. Being highly tolerant to pollutants and other abiotic stresses, giant reed (Arundo donax L.) is a suitable biomass crop for phytoremediation of contaminated soils. We report the results of a two-year open-air lysimeter study aimed at assessing the adaptability of giant reed to grow on industrial substrates polluted by Pb and Zn and at testing commercial humic acids from leonardite as improvers of plant performance. We evaluated giant reed potential for: 1) biomass production for energy or biomaterial recovery; 2) PTE phytoextraction and 3) soil fertility restoration. Chemical fertility was monitored by measuring soil C while soil biological fertility was estimated by quantifying the abundance of bacterial functional genes regulating nitrogen fixation (nifH) and nitrification (amoA). Giant reed above-ground growth on the polluted soils was slightly lower (-16%) than on a non-polluted soil, with a preferential storage of biomass in the rhizome acting as a survival strategy in limiting growing conditions. Humic acids improved plant stress tolerance and production levels. As aerial biomass (shoots) did not accumulate PTEs, the plant in question can be used for bioenergy or biopolymer production. In contrast, below-ground biomass (rhizomes) accumulated PTEs, and can thus be harvested and removed from soil to improve phytoremediation protocols and also used as industrial biofuel. Giant reed growth increased the abundance of N-cycling bacteria and soil C in the rhizospheric soil, as well as reduced soil Pb and Zn EDTA extractable fraction.

Abstract TP373: Tracts Enfolded by Small Hematomas Remain Intact in Acute Intracerebral Hemorrhage

Background: Mortality can be predicted by intracerebral hemorrhage (ICH) volume, but motor recovery in survivors is variable. Motor impairment is likely related to the spatial relationship between the hematoma and corticospinal tract (CST). Diffusion Tensor Imaging (DTI) tractography can be used to visualize white matter tracts in three dimensions. We hypothesized that the interaction between the hematoma and CST would predict motor impairment in ICH patients.

Methods: ICH patients with small-moderate hematomas were prospectively imaged with CT and DTI within 14 days of onset. Hematoma volume was assessed on CT using planimetric techniques. Three-dimensional recreations of the ipsilateral CST and the hematoma were made for each patient. The CST was categorized by interaction with the ICH as CST: Unaffected, Displaced, Partially Severed, Completely Severed, and Splitting the ICH. Motor function was classified as 'good' (NIHSS motor subscale 0-2) or 'poor' (3-8).

Results: Thirty patients (mean age 68±13) underwent CT at a median (IQR) of 2.3 (3.5)h and DTI at 2.0 (3.6, range 0.6-13) days. Median hematoma volume was 8.2 (23) ml.

Lesion distribution was: lobar 11 (37%), basal ganglia 18 (60%), brainstem 1 (3%). CSTs were primarily Displaced (n=9) or Unaffected (8), with the remainder being Partially Severed (4), Completely Severed (5), and Splitting the ICH (4). The latter 4 (13%) patients had small (<6ml, median 2.5 [3.0] ml) basal ganglia bleeds which enfolded the intact CST.

Motor score at Day 7 was good in 50% of patients. Good outcome was seen in 8 (100%) Unaffected, 4 (44%) Displaced, 1 (25%) Partially Severed, 0 (0%) Severed and 2 (50%) Splitting the ICH patients. Logistic regression indicated that good motor score was predicted by CST category (r=2.3, p=0.016).

Conclusion: CST integrity can be maintained when enfolded by small basal ganglia bleeds. Diffusion tractography patterns may be useful for predicting motor scores in small to moderate-sized hematomas.

Abstract 214: Corticospinal Tract Integrity is Acutely Maintained Within Perihematoma Edema

Background: Perihematoma edema in intracerebral hemorrhage (ICH) is thought to be associated with tissue injury. Fractional Anisotropy (FA), as measured with Diffusion Tensor Imaging (DTI), can be used to assess white matter integrity. We tested the hypotheses that sections of the Corticospinal Tract (CST) passing directly through edema would 1) have low FA relative to the entire tract and 2) predict motor score in ICH patients.

Methods: Patients were prospectively imaged with DTI within 14 days of symptom onset. Hematoma volume was measured on CT using planimetric techniques. Edema volume was assessed on CT using a 5-23 Hounsfield Unit threshold. Mean FA was measured in the edematous region (‘perihematoma edema'), the entire ipsilateral CST, and in the portion of CST passing through the perihematoma edema ('edematous CST'). Motor function was evaluated with a composite of the upper and lower extremity NIHSS motor score (0=normal, 8=hemiplegia).

Results: Patients (n=27, mean age 67±13) were scanned with DTI at a median of 2 (3) days. Hematoma distribution was: lobar 5 (18%), basal ganglia 21 (78%), and brainstem 1 (4%). Median acute ICH volume was 8.2 (22) ml at 2 (2)h. Acute edema volume was 0.9 (1.8) ml and grew to 1.9 (3.9) ml at 26h (26). NIHSS motor score was 3 (6) at 72h and 3 (7) at day 7.

FA in the edema was significantly lower (0.23±0.06) than in contralateral mirror regions (0.37 ±0.07, p<0.0001). Mean FA in the edematous CST was lower (0.34±0.08) than FA in the entire ipsilateral CST (0.44±0.04, p<0.0001), but higher than FA in the perihematoma edema (0.25±0.06, p<0.0001).

There was a weak correlation between FA in the edematous CST and 72h motor score (r= -0.40, p=0.050,) which disappeared at day 7 (r= -0.34, p=0.131). FA in the edematous CST was not related to time to scan (r=-0.027, p=0.892).

Hematoma volume predicted FA in the edematous CST (ß=-0.46, 95% CI:[-0.05- -0.01]; p=0.015). Perihematoma edema volume did not predict FA in the edematous CST independently of the ICH (ß=-0.29, [-0.1-0.04]; p=0.475).

Conclusion: FA is decreased in the CST where it passes through the edema, though not to the extent of the surrounding edema. The transient relationship between decreased FA and motor function suggests that edema temporarily impairs tract function but not integrity.

Dabigatran Therapy in Acute Ischemic Stroke Patients Without Atrial Fibrillation

Background and Purpose—

Acute ischemic stroke patients are at risk of early recurrence. We tested the feasibility and safety of initiating dabigatran in patients, within 24 hours of minor stroke in patients without atrial fibrillation.

Methods—

Minor stroke patients (National Institutes of Health Stroke Scale score ≤3) without atrial fibrillation and evidence of acute infarction on magnetic resonance imaging were treated with dabigatran. Treatment began within 24 hours of onset and was continued for 30 days. The primary end point was symptomatic hemorrhagic transformation.

Results—

A total of 53 patients with median (interquartile range) age of 68 (57–77) years and National Institutes of Health Stroke Scale score of 1 (0–2) were enrolled. Baseline diffusion-weighted imaging volume was 0.8 (0.3–2.4) mL. No patients experienced symptomatic hemorrhagic transformation. Three patients had evidence of asymptomatic petechial hemorrhagic transformation on day 7, which remained stable at day 30, while continuing dabigatran.

Conclusions—

Dabigatran treatment within 24 hours of minor stroke is feasible. A larger randomized trial is required to confirm the safety and efficacy of this treatment approach.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT 01769703.

Reduction of Diffusion-Weighted Imaging Contrast of Acute Ischemic Stroke at Short Diffusion Times

Background and Purpose—

Diffusion-weighted imaging (DWI) of tissue water is a sensitive and specific indicator of acute brain ischemia, where reductions of the diffusion of tissue water are observed acutely in the stroke lesion core. Although these diffusion changes have been long attributed to cell swelling, the precise nature of the biophysical mechanisms remains uncertain.

Methods—

The potential cause of diffusion reductions after stroke was investigated using an advanced DWI technique, oscillating gradient spin-echo DWI, that enables much shorter diffusion times and can improve specificity for alterations of structure at the micron level.

Results—

Diffusion measurements in the white matter lesions of patients with acute ischemic stroke were reduced by only 8% using oscillating gradient spin-echo DWI, in contrast to a 37% decrease using standard DWI. Neurite beading has recently been proposed as a mechanism for the diffusion changes after ischemic stroke with some ex vivo evidence. To explore whether beading could cause such differential results, simulations of beaded cylinders and axonal swelling were performed, yielding good agreement with experiment.

Conclusions—

Short diffusion times result in dramatically reduced diffusion contrast of human stroke. Simulations implicate a combination of neuronal beading and axonal swelling as the key structural changes leading to the reduced apparent diffusion coefficient after stroke.