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392 result(s) for "Levi, Christopher"
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Reperfusion therapy in acute ischemic stroke: dawn of a new era?
Following the success of recent endovascular trials, endovascular therapy has emerged as an exciting addition to the arsenal of clinical management of patients with acute ischemic stroke (AIS). In this paper, we present an extensive overview of intravenous and endovascular reperfusion strategies, recent advances in AIS neurointervention, limitations of various treatment paradigms, and provide insights on imaging-guided reperfusion therapies. A roadmap for imaging guided reperfusion treatment workflow in AIS is also proposed. Both systemic thrombolysis and endovascular treatment have been incorporated into the standard of care in stroke therapy. Further research on advanced imaging-based approaches to select appropriate patients, may widen the time-window for patient selection and would contribute immensely to early thrombolytic strategies, better recanalization rates, and improved clinical outcomes.
Collateral assessment on magnetic resonance imaging/angiography up to 30 hours after stroke onset
We aimed to validate hyperintense vessel sign (HVS) on FLAIR imaging or posterior cerebral artery (PCA) laterality on MR angiography beyond 4.5 hours after stroke onset. Data from acute ischemic stroke patients with internal carotid or middle cerebral artery occlusion who underwent CT perfusion imaging at baseline, follow-up MR perfusion imaging and angiography within 30 hours after stroke, without effective recanalization on follow-up imaging, were analysed retrospectively. Patients were separately classified as high or low HVS (>5 or ≤5 slices of HVS), and PCA laterality positive or negative group. We compared core and penumbra volumes at follow-up imaging and neurological outcomes between high or low HVS group, and between PCA laterality positive or negative group. Of 49 patients analyzed, four patients with artifacts were excluded and 45 were classified into high (n = 23) or low (n = 22) HVS group. High group had a smaller core volume (median 32 ml versus 109 ml, p = 0.004), larger penumbra volume at follow-up (68 ml versus 0 ml, p = 0.001), and better outcomes (modified Rankin Scale at three months, 3 versus 5, p = 0.03). For PCA laterality analysis, 1 patient with previously occluded PCA was excluded and 48 patients were classified as positive (n = 22) or negative (n = 26). Positive group had larger core volume (116 ml versus 37 ml), and no significant differences in penumbral volumes or outcomes. Prominent HVS in later time was associated with small core volume, persistent penumbra volume and favorable outcomes.
A Randomized Trial of Tenecteplase versus Alteplase for Acute Ischemic Stroke
In this phase 2B trial involving 75 patients with acute ischemic stroke, tenecteplase was more effective than alteplase in achieving reperfusion and clinical improvement at 24 hours. Bleeding complications were similar in the two groups. Thrombolytic treatment with alteplase, a recombinant tissue plasminogen activator, for acute ischemic stroke is of proven benefit. 1 However, alteplase is far from ideal, with incomplete and often delayed reperfusion in many patients. 2 Tenecteplase, a genetically engineered mutant tissue plasminogen activator, has some pharmacokinetic advantages over alteplase. 3 A balance between efficacy and risk of bleeding in the treatment of stroke appears to be achieved at a lower dose of tenecteplase than the dose used for myocardial infarction. 4 A recent dose-ranging study of tenecteplase involving patients with acute ischemic stroke, which used standard clinical selection criteria, showed that a dose of 0.4 . . .
Low-Dose versus Standard-Dose Intravenous Alteplase in Acute Ischemic Stroke
This randomized comparison of low-dose and standard-dose alteplase in acute ischemic stroke did not establish noninferiority of low-dose alteplase for the primary outcome of death or disability at 90 days. Fewer patients had intracerebral hemorrhages in the low-dose group. Thrombolytic therapy with intravenous alteplase (recombinant tissue-type plasminogen activator) at a dose of 0.9 mg per kilogram of body weight is an effective treatment for acute ischemic stroke, despite increasing the risk of intracerebral hemorrhage. 1 – 3 However, the Japanese drug safety authority has approved the use of alteplase at a dose of 0.6 mg per kilogram after an uncontrolled, open-label study showed that this dose resulted in equivalent clinical outcomes and a lower risk of intracerebral hemorrhage than that reported in published studies in which the 0.9-mg-per-kilogram dose was used. 4 Other registry studies in Asia 5 – 11 have shown inconsistent results, . . .
Failure of Collateral Blood Flow is Associated with Infarct Growth in Ischemic Stroke
Changes in collateral blood flow, which sustains brain viability distal to arterial occlusion, may impact infarct evolution but have not previously been demonstrated in humans. We correlated leptomeningeal collateral flow, assessed using novel perfusion magnetic resonance imaging (MRI) processing at baseline and 3 to 5 days, with simultaneous assessment of perfusion parameters. Perfusion raw data were averaged across three consecutive slices to increase leptomeningeal collateral vessel continuity after subtraction of baseline signal analogous to digital subtraction angiography. Changes in collateral quality, Tmax hypoperfusion severity, and infarct growth were assessed between baseline and days 3 to 5 perfusion-diffusion MRI. Acute MRI was analysed for 88 patients imaged 3 to 6 hours after ischemic stroke onset. Better collateral flow at baseline was associated with larger perfusion-diffusion mismatch (Spearman's Rho 0.51, P < 0.001) and smaller baseline diffusion lesion volume (Rho − 0.70, P < 0.001). In 30 patients without reperfusion at day 3 to 5, deterioration in collateral quality between baseline and subacute imaging was strongly associated with absolute (P = 0.02) and relative (P < 0.001) infarct growth. The deterioration in collateral grade correlated with increased mean Tmax hypoperfusion severity (Rho − 0.68, P < 0.001). Deterioration in Tmax hypoperfusion severity was also significantly associated with absolute (P = 0.003) and relative (P = 0.002) infarct growth. Collateral flow is dynamic and failure is associated with infarct growth.
Implementation of evidence-based treatment protocols to manage fever, hyperglycaemia, and swallowing dysfunction in acute stroke (QASC): a cluster randomised controlled trial
We assessed patient outcomes 90 days after hospital admission for stroke following a multidisciplinary intervention targeting evidence-based management of fever, hyperglycaemia, and swallowing dysfunction in acute stroke units (ASUs). In the Quality in Acute Stroke Care (QASC) study, a single-blind cluster randomised controlled trial, we randomised ASUs (clusters) in New South Wales, Australia, with immediate access to CT and on-site high dependency units, to intervention or control group. Patients were eligible if they spoke English, were aged 18 years or older, had had an ischaemic stroke or intracerebral haemorrhage, and presented within 48 h of onset of symptoms. Intervention ASUs received treatment protocols to manage fever, hyperglycaemia, and swallowing dysfunction with multidisciplinary team building workshops to address implementation barriers. Control ASUs received only an abridged version of existing guidelines. We recruited pre-intervention and post-intervention patient cohorts to compare 90-day death or dependency (modified Rankin scale [mRS] ≥2), functional dependency (Barthel index), and SF-36 physical and mental component summary scores. Research assistants, the statistician, and patients were masked to trial groups. All analyses were done by intention to treat. This trial is registered at the Australia New Zealand Clinical Trial Registry (ANZCTR), number ACTRN12608000563369. 19 ASUs were randomly assigned to intervention (n=10) or control (n=9). Of 6564 assessed for eligibility, 1696 patients' data were obtained (687 pre-intervention; 1009 post-intervention). Results showed that, irrespective of stroke severity, intervention ASU patients were significantly less likely to be dead or dependent (mRS ≥2) at 90 days than control ASU patients (236 [42%] of 558 patients in the intervention group vs 259 [58%] of 449 in the control group, p=0·002; number needed to treat 6·4; adjusted absolute difference 15·7% [95% CI 5·8–25·4]). They also had a better SF-36 mean physical component summary score (45·6 [SD 10·2] in the intervention group vs 42·5 [10·5] in the control group, p=0·002; adjusted absolute difference 3·4 [95% CI 1·2–5·5]) but no improvement was recorded in mortality (21 [4%] of 558 in intervention group and 24 [5%] of 451 in the control group, p=0·36), SF-36 mean mental component summary score (49·5 [10·9] in the intervention group vs 49·4 [10·6] in the control group, p=0·69) or functional dependency (Barthel Index ≥60: 487 [92%] of 532 patients vs 380 [90%] of 423 patients; p=0·44). Implementation of multidisciplinary supported evidence-based protocols initiated by nurses for the management of fever, hyperglycaemia, and swallowing dysfunction delivers better patient outcomes after discharge from stroke units. Our findings show the possibility to augment stroke unit care. National Health & Medical Research Council ID 353803, St Vincent's Clinic Foundation, the Curran Foundation, Australian Diabetes Society-Servier, the College of Nursing, and Australian Catholic University.
Safety and efficacy of sonothrombolysis for acute ischaemic stroke: a multicentre, double-blind, phase 3, randomised controlled trial
Pulsed-wave ultrasound increases the exposure of an intracranial thrombus to alteplase (recombinant tissue plasminogen activator), potentially facilitating early reperfusion. We aimed to ascertain if a novel operator-independent transcranial ultrasound device delivering low-power high-frequency ultrasound could improve functional outcome in patients treated with alteplase after acute ischaemic stroke. We did a multicentre, double-blind, phase 3, randomised controlled trial (CLOTBUST-ER) at 76 medical centres in 14 countries. We included patients with acute ischaemic stroke (National Institutes of Health Stroke Scale score ≥10) who received intravenous thrombolysis (alteplase bolus) within 3 h of symptom onset in North America and within 4·5 h of symptom onset in all other countries. Participants were randomly allocated (1:1) via an interactive web response system to either active ultrasound (2 MHz pulsed-wave ultrasound for 120 min [sonothrombolysis]; intervention group) or sham ultrasound (control group). Ultrasound was delivered using an operator-independent device, which had to be activated within 30 min of the alteplase bolus. Participants, investigators, and those assessing outcomes were unaware of group assignments. The primary outcome was improvement in the modified Rankin Scale score at 90 days in patients enrolled within 3 h of symptom onset, assessed in the intention-to-treat population as a common odds ratio (cOR) using ordinal logistic regression shift analysis. This trial is registered with ClinicalTrials.gov, number NCT01098981. The trial was stopped early by the funder after the second interim analysis because of futility. Between August, 2013, and April, 2015, 335 patients were randomly allocated to the intervention group and 341 patients to the control group. Compared with the control group, the adjusted cOR for an improvement in modified Rankin Scale score at 90 days in the intervention group was 1·05 (95% CI 0·77–1·45; p=0·74). 51 (16%) of 317 patients in the intervention group and 44 (13%) of 329 patients in the control group died (unadjusted OR 1·24, 95% CI 0·80–1·92; p=0·37) and 83 (26%) and 79 (24%), respectively, had serious adverse events (1·12, 0·79–1·60; p=0·53). Sonothrombolysis delivered by an operator-independent device to patients treated with alteplase after acute ischaemic stroke was feasible and most likely safe, but no clinical benefit was seen at 90 days. Sonothrombolysis could be further investigated either in randomised trials undertaken in stroke centres that are dependent on patient transfer for endovascular reperfusion therapies or in countries where these treatments cannot yet be offered as the standard of care. Cerevast Therapeutics.
Effect of short-term exposure to air pollution on daily cardio- and cerebrovascular hospitalisations in areas with a low level of air pollution
Exposure to air pollution is associated with increased cardio- and cerebrovascular diseases. However, the evidence regarding the short-term effect of air pollution on cardio- and cerebrovascular hospitalisations in areas with relatively low air pollution levels is limited. This study aims to examine the effect of short-term exposure to different air pollutants on hospital admissions due to cardio- and cerebrovascular diseases in rural and regional Australia with low air pollution. The study was conducted in five local Government areas of Hunter New England Local Health District (HNE-LHD). Hospitalisation data from January 2018 to February 2020 (820 days) were accessed from the HNE-LHD admitted patients’ dataset. Poisson regression model was used to examine the association between the exposure (air pollutants) and outcome variables (hospitalisation due to cardio- and cerebrovascular disease). The concentrations of gaseous air pollutants, Sulphur Dioxide (SO 2 ), Nitrogen Dioxide (NO 2 ), Ozone (O 3 ), Carbon Monoxide (CO), and Ammonia (NH 3 ) were below national benchmark concentrations for every day of the study period. In single pollutant models, SO 2 and NO 2 significantly increased the daily number of cardio- and cerebrovascular hospitalisations. The highest cumulative effect for SO 2 was observed across lag 0–3 days (Incidence Rate Ratio, IRR: 1.77; 95% Confidence Interval, CI: 1.18–2.65; p -value: 0.01), and for NO 2 , it was across lag 0–2 days (IRR: 1.13; 95% CI: 1.02–1.25; p -value: 0.02). In contrast, higher O 3 was associated with decreased cardio- and cerebrovascular hospitalisations, with the largest effect observed at lag 0 (IRR: 0.94; 95% CI: 0.89–0.98; p -value: 0.02). In the multi-pollutant model, the effect of NO 2 remained significant at lag 0 and corresponded to a 21% increase in cardio- and cerebrovascular hospitalisation (95% CI: 1–44%; p -value = 0.04). Thus, the study revealed that gaseous air pollutants, specifically NO 2 , were positively related to increased cardio- and cerebrovascular hospitalisations, even at concentrations below the national standards.
Pretreatment Diffusion- and Perfusion-MR Lesion Volumes Have a Crucial Influence on Clinical Response to Stroke Thrombolysis
We hypothesized that pretreatment magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) lesion volumes may have influenced clinical response to thrombolysis in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET). In 98 patients randomized to intravenous (IV) tissue plasminogen activator (tPA) or placebo 3 to 6 h after stroke onset, we examined increasing acute DWI and PWI lesion volumes (Tmax—with 2-sec delay increments), and increasing PWI/DWI mismatch ratios, on the odds of both excellent (modified Rankin Scale (mRS): 0 to 1) and poor (mRS: 5 to 6) clinical outcome. Patients with very large PWI lesions (most had internal carotid artery occlusion) had increased odds ratio (OR) of poor outcome with IV-tPA (58% versus 25% placebo; OR=4.13, P=0.032 for Tmax +2-sec volume >190 mL). Excellent outcome from tPA treatment was substantially increased in patients with DWI lesions <18 mL (77% versus 18% placebo, OR=15.0, P<0.001). Benefit from tPA was also seen with DWI lesions up to 25 mL (69% versus 29% placebo, OR=5.5, P=0.03), but not for DWI lesions >25 mL. In contrast, increasing mismatch ratios did not influence the odds of excellent outcome with tPA. Clinical responsiveness to IV-tPA, and stroke outcome, depends more on baseline DWI and PWI lesion volumes than the extent of perfusion–diffusion mismatch.