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  • Campbell, Bruce C  (9)
  • Parsons, Mark W  (9)
  • English  (9)
  • 1
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 51, No. Suppl_1 ( 2020-02)
    Abstract: Introduction: The role of mobile stroke units (MSU) in earlier provision of thrombolysis (tPA) is well described, but the effect on endovascular thrombectomy (EVT) is less clear. Despite the theoretical advantages of improved triage and prehospital activation of EVT services, only a small effect on hospital arrival to EVT start has so far been described. We aimed to analyze the clinical benefit of EVT and tPA from operation of the Melbourne MSU in the first year. Methods: First ambulance dispatch to reperfusion treatment commencement (DTT) times between MSU patients receiving reperfusion therapy from November 2017-18 were compared to consecutive control cases during MSU operating hours presenting across metropolitan Melbourne for tPA, and direct and metropolitan transfer patients presenting to the Royal Melbourne Hospital for EVT. Median time difference between MSU and controls was regarded as the 50 th quantile using quantile regression analysis. Comparative disability avoidance was estimated for EVT and tPA using calculated time savings. Results: In the first calendar year, the MSU operated for 30.5 service (7-day) weeks. Prehospital tPA was administered to 52 patients, with median time differences for dispatch-to-hospital/scene-arrival of -30 minutes (p 〈 0.0001) and arrival-to-tPA of -17 minutes (p=0.001), resulting in overall DTT time saving of 47 minutes compared to controls. In the same timeframe, 26 patients received EVT with median time difference of -51 minutes (p 〈 0.0001) compared to controls. Prehospital notification resulted in median time difference of -17 minutes (p=0.001) for EVT center-arrival to groin puncture. Using published estimates of disability avoidance per minute of time saved for each reperfusion therapy, the clinical impact of the EVT time saving for the 26 MSU patients is equivalent to the clinical impact of 67 tPA patients treated on the MSU. Conclusion: The clinical impact of Melbourne MSU operation on earlier provision of EVT was greater than that of tPA in the first year of operation, reflecting facilitated triage to EVT centers and early prehospital notification. In locales where EVT capability is limited or unevenly distributed such as Melbourne, facilitation of EVT is likely to be a central driver of MSU operation.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2020
    detail.hit.zdb_id: 1467823-8
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  • 2
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 51, No. Suppl_1 ( 2020-02)
    Abstract: Introduction: Intravenous alteplase reduces disability after ischemic stroke in patients 4.5-9h after onset and with wake-up onset stroke who have favorable perfusion imaging. We examined the benefit of reperfusion in reducing disability, including by onset to randomization time strata in the EXTEND and EPITHET randomized trials. Methods: Patients were randomized to alteplase or placebo after perfusion mismatch imaging. Reperfusion was defined as 〉 90% reduction in Tmax 〉 6s lesion volume at 24h. Ordinal logistic regression adjusted for baseline age and NIHSS was used to analyze functional improvement in day 90 modified Rankin scale overall, including a reperfusion*time to randomization interaction term, and in the 4.5-6h, 6-9h and wake-up time strata. Symptomatic hemorrhage was defined as large parenchymal hematoma with ≥4 point NIHSS increase (SITS). Results: Reperfusion was assessable in 270/294 (92%) patients, 68/133 (51%) alteplase and 38/137 (28%) placebo reperfused (p 〈 0.001). Median age 76 (IQR 66-81) in reperfused vs 74 (IQR 64.5-81) in non-reperfused, median baseline NIHSS 10 (IQR 7-15) in reperfused vs 12 (IQR 8-17.5) in non-reperfused. Overall, reperfusion was associated with common odds ratio 7.7 (95%CI 4.6-12.8, p 〈 0.0001) in ordinal “shift” analysis. There was no heterogeneity in the beneficial effect of reperfusion effect by time to randomization (p=0.63). Reperfusion was associated with significantly improved functional outcome in each of the 4.5-6h, 6-9h and wake-up time strata (figure). Symptomatic hemorrhage, assessed in all 294 patients, occurred in 3/51 (5.9%) 4.5-6h, 2/28 (7.1%) 6-9h, 4/73 (5.5%) wake-up stroke in the alteplase-treated patients (van Elteren p=0.66). Conclusions: Strong benefits of reperfusion in all time strata without differential risk in symptomatic hemorrhage support the durable treatment effect of alteplase in perfusion mismatch-selected patients throughout the 4.5-9h and wake-up stroke time window.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2020
    detail.hit.zdb_id: 1467823-8
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  • 3
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 44, No. suppl_1 ( 2013-02)
    Abstract: Objective: Hemorrhagic transformation in ischemic stroke is a potentially life threatening complication of thrombolysis. Using perfusion MRI, very low cerebral blood volume (VLCBV) strongly predicts hemorrhagic transformation after reperfusion. CT perfusion (CTP) is currently more widely accessible than MRI and recent data have shown that CT relative cerebral blood flow (relCBF) provides a better estimate of infarct core than CBV. We aimed to determine the optimal parameter to predict hemorrhagic transformation using whole brain CTP. Methods: Patients with ischemic stroke were imaged with whole brain CTP within 6hrs of symptom onset. Hemorrhagic transformation was assessed on CT/MRI within 7 days of stroke using ECASS grade. CBF and CBV were analyzed within a relative time to peak 〉 4sec region of interest. Results were expressed as volumes below a given percentile relative to the contralateral hemisphere (relCBF and relCBV). Receiver operating characteristic (ROC) and logistic regression analysis were performed to determine the optimal parameter and percentile threshold correlating with parenchymal hemorrhage (PH). Results: 128 patients with acute CTP were analyzed, median age 76yr (IQR 66-83), median NIHSS 13 (IQR 9-16), 59% received IV thrombolysis. 11 patients had PH on follow-up. On ROC analysis, the optimal threshold for very low CBF (VLCBF) was at the 〈 0 th centile. VLCBF was significantly associated with PH in ROC analysis (AUC=0.760, p 〈 0.01) whereas VLCBV (AUC 0.638 at 〈 5 th centile, 0.618 at 〈 2.5 th centile, 0.440 at 〈 0 th centile) was not significant. Using VLCBF, the optimal lesion volume to predict PH was 〉 3mL with OR 12.0 (95%CI 2.4-58), sensitivity 0.82 (95%CI 0.48-0.98), specificity 0.73 (95%CI 0.64-0.80), negative predictive value 0.98 (95%CI 0.92-1.0) and positive predictive value 0.22 (95%CI 0.11-0.38). In logistic regression, PH was associated with increased VLCBF (p 〈 0.01) but not with VLCBV (p=0.08). The Bayesian information criterion for VLCBF compared to VLCBV was +5 indicating improved model fit. Conclusions: VLCBF appears to be more reliably associated with hemorrhagic transformation than VLCBV when CT perfusion is used. This may be due to reduced ability of VLCBV to distinguish regions of ischemia from normal white matter.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2013
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  • 4
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 51, No. Suppl_1 ( 2020-02)
    Abstract: Background: Severity-based selection tools for large vessel occlusion (LVO) are limited by lack of validation in unselected prehospital stroke patients and concerns regarding delayed thrombolysis (tPA) and comprehensive stroke center (CSC) burdening. We examined these issues in a real-world validation of the two exam step (severe arm motor + speech or neglect) ACT-FAST LVO triage algorithm. Methods: The ACT-FAST statewide validation involved 15 metro and 17 rural hospitals in Victoria, Australia from Nov 2017-July 2019 with training of paramedics using an 8 min video. Prehospital paramedic assessments were correlated with hospital imaging to determine presence of LVO. Data were then examined for diagnostic accuracy, time saving for direct bypass to CSC using a validated Google maps model, rates and magnitude of delayed tPA in false-positive non-LVO infarcts, and extra CSC workload. Results: In 517 completed assessments, 58% involving non-EVT centers and including 114 (22%) LVO, ACT-FAST sensitivity was 81% (92/114) and specificity was 81% (325/403; 89% if ICH are not regarded as false-positive) for LVO. Figure compares to other LVO scales. Bypass to CSC was modelled to save median 71 min for analysis of 29 thrombectomy patients requiring inter-hospital transfer. Of 27 non-LVO infarcts with false positive ACT-FAST, only 4 (15%) received tPA at a non-CSC center, and bypass would have only added median 10 mins in these cases. The increase in CSC presentation using ACT-FAST triage was estimated to be 2-3.3 patients/week using estimated 7,200 suspected stroke cases/year across entire metro Victoria. Conclusion: In comprehensive real-world validation, the simple ACT-FAST algorithm detected LVO or ICH in almost 80% of positive assessments with highly favorable comparison to other scales. Prehospital bypass to CSC substantially reduces thrombectomy delay, and appears to strongly outweigh negatives of bypassing false positive cases on tPA delay and CSC overburdening.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2020
    detail.hit.zdb_id: 1467823-8
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  • 5
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 44, No. suppl_1 ( 2013-02)
    Abstract: Background and purpose: CT perfusion (CTP) provides rapid and accessible imaging of ischemic stroke pathophysiology. Studies with limited brain coverage CTP have suggested that relative cerebral blood flow (relCBF) is the optimal CTP parameter to define irreversible infarction. We analyzed patients with whole brain CT perfusion and contemporaneous MR perfusion-diffusion imaging to confirm the optimal CTP parameter for infarct core and compare mismatch classification between MR and CT. Methods: Acute ischemic stroke patients 〈 6hr after onset had whole brain CTP (320slice) closely followed by perfusion-diffusion MRI. Maps of CBF, CBV and time-to-peak of the deconvolved tissue residue function (Tmax) were generated by RAPID automated perfusion analysis software (Stanford University) using delay insensitive deconvolution. The optimal CTP map to identify infarct core was selected by maximizing the average Dice co-efficient across the same threshold range for all patients using co-registered diffusion lesion (manually outlined to its maximal visual extent) as reference region. Mismatch classification agreement between CT and MRI was then assessed using 2 definitions: mismatch ratio a) 〉 1.2 or b) 〉 1.8, absolute mismatch a) 〉 10mL or b) 〉 15mL, infarct core 〈 70mL. Results: In 28 patients imaged 〈 6hr from stroke onset (median age 69, median onset to CT 180min, median CT to MR 69min), relCBF provided the most accurate estimate for infarct core, significantly better than absolute or relative CBV (both p 〈 0.001). Using relCBF to generate acute CTP infarct core volumes, the median magnitude of volume difference versus diffusion MR was 6.9mL, interquartile range 1.6-27.4mL. CTP mismatch between relCBF core and Tmax 〉 6sec perfusion lesion was assessed in 25 patients (3/28 had no MR perfusion). CTP and MR perfusion-diffusion mismatch classification agreed in 23/25 (92%) patients (kappa 0.84) using either definition. Conclusions: This study using whole brain CTP confirms the greater accuracy of CBF over CBV for estimation of the infarct core. The 〉 90% agreement in mismatch classification between CTP and MRI supports the concept that both modalities can identify similar patient populations for clinical trials of reperfusion therapies.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2013
    detail.hit.zdb_id: 1467823-8
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  • 6
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 47, No. suppl_1 ( 2016-02)
    Abstract: Background: EXTEND is an investigator-initiated, randomised, double-blind and placebo-controlled Phase III trial of intravenous alteplase vs placebo in patients with ischemic stroke 4.5-9 hours from stroke onset or wake-up-stroke (WUS). The prevalence of intra-cranial vessel occlusion in WUS patients remains to be determined and can guide the development of optimal therapy for this unique group of stroke patients. Objective: To study the prevalence and characteristics of intra-cranial vessel occlusion in this WUS cohort. Methods: Ischemic stroke patients within 4.5-9 hours from stroke onset or with WUS (time of WUS onset defined as the midpoint between time to sleep and awakening with the stroke symptoms) are eligible for enrollment. Criteria for entry into the trial include perfusion-diffusion mismatch using a perfusion threshold of Tmax 〉 6sec and a perfusion:diffusion lesion volume ratio of 〉 1.2. Diffusion lesion volume must be 〈 70mL based on assessment by automated RAPID software. Intra-cranial vessel occlusion was assessed on MR or CT angiogram performed at randomisation and 24 later. Two expert readers assessed these images independently. Results: 97 patients had images with adequate quality, including 63 (65%) in the WUS group with median age of 77.0 yrs (IQR 67.0, 81.0) and NIHSS of 14.0 (9.0, 19.0). 62 of 63 patients (98%) had vessel occlusion with 44.4% involving M1 of the middle cerebral artery, 17.5% M2, 4.8% M3, 25.4% both internal carotid artery (ICA) and M1, 4.8% ICA alone and 3.1% the posterior cerebral artery. The median ischemic core volume was 15.0 ml (6.5, 31.5), Tmax 〉 6 volume 88.5ml (58.0, 122.0), mismatch volume 65.5ml (42.8, 92.0), and ratio of 4.8 (2.5, 8.7). 19 patients (30%) demonstrated recanalization on follow-up imaging. Conclusion: In WUS patients there is a very high rate of intracranial vessel occlusion with relatively large volumes of salvageable penumbral tissue. Intravenous thrombolytic therapy followed by thrombectomy in selected cases may be an appropriate therapeutic option with safety and efficacy remaining to be established in randomized controlled trials.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2016
    detail.hit.zdb_id: 1467823-8
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  • 7
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 45, No. suppl_1 ( 2014-02)
    Abstract: Objective: Cerebral volume changes post stroke have recently been described and may correlate with clinical outcome. We aimed to determine whether peri infarct measurement of the neuronal marker N-Acetylaspartic acid (NAA) on Magnetic Resonance Spectroscopy (MRS) predicts progressive cerebral volume change after stroke. Methods: 11 patients (7 male) with supratentorial ischemic stroke underwent serial MRI within 1 week of onset, and at 1 and 3 months. Imaging was performed on a 3T Siemens Trio scanner. Structural imaging utilized a T1-weighted axial MPRAGE acquisition (1mm slices, TR1.9sec, TE2.82msec). NAA estimation was performed at the baseline scan using single voxel MRS (TE30msec, 3x3x3cm voxels). The voxel was placed in the peri infarct region as determined by assessment of the diffusion weighted image. Quantitative MRS analysis was performed using LCmodel using water referencing. Brain tissue volume, normalized for subject head size, was estimated with SIENAX, part of FSL. Due to anticipated effects of edema on initial cerebral volume, changes in grey, white and total brain volume were assessed as percentage change between the 1 and 3 month scans. Results: Mean age was 71yr (IQR 62-79yr). Median baseline NIHSS was 11 (IQR 6-14). Mean baseline grey, white and total brain volume were 713ml (IQR 683-749), 731mL (IQR 721-747) and 1444mL (IQR 1384-1503) respectively. There was a significant correlation between age and baseline grey matter volume (r2=0.73, p=0.001) and total brain volume (r2=0.74, p=0.001). Mean peri infarct NAA concentration was 6.2mM (SD 1.3) compared with 7.0mM (SD 1.2) in the contralateral hemisphere (p=0.09, paired t-test). Mean percentage grey, white and total brain volume changes were 1.2% (IQR -1.8-4.1), 0.4% (IQR -2.2-3.7) and 0.8% (IRQ -1.0-2.6) respectively. There was a significant correlation between baseline NAA in the peri infarct region and change in white matter volume between the 1 and 3 month time points (r2=0.26, p=0.008). Conclusions: Estimation of the neuronal marker NAA using MRS may signify varying degrees of neuronal damage after stroke which may correlate with the severity of axonal degeneration and subsequent white matter volume changes. Further validation and correlation with clinical outcomes is required.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2014
    detail.hit.zdb_id: 1467823-8
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  • 8
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 47, No. suppl_1 ( 2016-02)
    Abstract: Background: EXTEND is a randomised, double-blind, placebo-controlled Phase III trial of intravenous alteplase vs. placebo among patients with ischemic stroke 4.5-9 hours from stroke onset or wake-up-stroke (WUS). There is uncertainty about the extent of salvageable tissue in this crucial time window for exploring therapeutic options. Whether WUS represents a plausible patient group for therapy is worthy exploring Objective: To determine the penumbral mismatch and ischaemic core volumes in the EXTEND cohort and compare these characteristics between WUS and non-WUS subsets. Methods: Patients with ischemic stroke within 4.5-9 hours from stroke onset and WUS patients (time of WUS onset defined as the midpoint between time to sleep and awakening with the stroke symptoms) are eligible for enrollment. Criteria for trial entry include perfusion-diffusion mismatch using a perfusion threshold of Tmax 〉 6sec and a perfusion:diffusion lesion volume ratio of 〉 1.2. Ischemic core must be 〈 70mL based on assessment by automated RAPID software on MR or CT platforms (Stanford). Results: 105 patients have been randomised to date with median age of 78.0 (IQR 66.5, 82 yrs), median admission NIHSS of 14.0 (8.0, 18.0) and half being female. WUS patients (n=69, 66%) compared to non-WUS patients, WUS patients had comparable median NIHSS of 14 (8, 18) vs 14.5 (8.0, 14.3 p =0.5), larger ischemic core volume of 15.5 ml (7.0, 33ml) vs 4.0 ml (0, 24.0ml p =0.005), perfusion deficit volume of 86.0 ml (58.5, 121.8ml) vs 73.0 ml (48.0, 124.0 ml p=0.6), mismatch ratio of 4.4 ml (2.6, 8.6 ml) vs 5.9 ml (2.7, 24.4 p=0.8) and mismatch volume of 64.0 ml (38.5, 91.8ml) vs 62.0 ml (42.5ml, 103.5ml p=0.5). Conclusion: Within the EXTEND cohort, there is a clinically significant amount of salvageable penumbral tissue within the 4.5-9 hr time window. Patients with WUS have larger ischemic core compared to those in the non-WUS group. However, comparable salvageable mismatch volumes and baseline NIHSS are noted between groups. Tissue salvage has the potential to lead to clinical improvement in both groups.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2016
    detail.hit.zdb_id: 1467823-8
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  • 9
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 46, No. suppl_1 ( 2015-02)
    Abstract: Objective: Changes in remote brain structures after stroke may correlate with functional outcomes. We sought to investigate contralesional subcortical structural change after stroke. Methods: 15 patients with carotid territory ischemic stroke underwent 3T MRI within 7 days of onset and at 3 months. Imaging involved a 1mm T1 axial MPRAGE. In 6 patients with left hemispheric stroke, scans were inverted across the midline to allow group comparison. FIRST (Part of FSL) was used to segment subcortical structures including thalamus, pallidum, caudate, putamen, hippocampus, accumbens and brainstem. Analysis was restricted to the non-stroke hemisphere due to the confounding effect of stroke lesions and edema in the lesional hemisphere. Change in volume was assessed as percentage change between the time points. A vertex analysis was performed in order to also identify areas of significant surface atrophy. Briefly, a surface mesh is created for each structure at each time point. Vertex wise statistical analysis then allows for the identifications of areas of significant surface atrophy between baseline and follow-up within the group. Results: Mean age was 71y. Median baseline NIHSS was 9. Vertex analysis demonstrated atrophy over the superior and inferior surface of the contralesional thalamus between baseline and 3 months (figure, p 〈 0.05 multiple comparisons corrected). The median overall change in contralesional thalamic volume was -0.96% (IQR -0.11 - -1.98%), but this difference was not statistically significant (p=0.1). No statistically significant changes in other subcortical structures were found. Contralesional thalamus (blue) superior (A) and inferior (B) views with areas of significant atrophy (red) Conclusions: We have described post stroke surface changes in the contralesional thalamus. This may be a result of deafferentation occurring during the recovery phase. An analysis in a larger number of patients may allow correlation with clinical endpoints.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2015
    detail.hit.zdb_id: 1467823-8
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