OBJECTIVE:To test the transferability of the Helsinki stroke thrombolysis model that achieved a median 20-minute door-to-needle time (DNT) to an Australian health care setting.
METHODS:The existing ...“code stroke” model at the Royal Melbourne Hospital was evaluated and restructured to include key components of the Helsinki model1) ambulance prenotification with patient details alerting the stroke team to meet the patient on arrival; 2) patients transferred directly from triage onto the CT table on the ambulance stretcher; and 3) tissue plasminogen activator (tPA) delivered in CT immediately after imaging. We analyzed our prospective, consecutive tPA registry for effects of these protocol changes on our DNT after implementation during business hours (8 AM to 5 PM Monday–Friday) from May 2012.
RESULTS:There were 48 patients treated with tPA in the 8 months after the protocol change. Compared with 85 patients treated in 2011, the median (interquartile range) DNT was reduced from 61 (43–75) minutes to 46 (24–79) minutes (p = 0.040). All of the effect came from the change in the in-hours DNT, down from 43 (33–59) to 25 (19–48) minutes (p = 0.009), whereas the out-of-hours delays remain unchanged, from 67 (55–82) to 62 (44–95) minutes (p = 0.835).
CONCLUSION:We demonstrated rapid transferability of an optimized tPA protocol to a different health care setting. With the cooperation of ambulance, emergency, and stroke teams, we succeeded in the absence of a dedicated neurologic emergency department or electronic patient records, which are features of the Finnish system. The next challenge is providing the same service out-of-hours.
Differences in research methodology have hampered the optimization of Computer Tomography Perfusion (CTP) for identification of the ischemic core. We aim to optimize CTP core identification using a ...novel benchmarking tool. The benchmarking tool consists of an imaging library and a statistical analysis algorithm to evaluate the performance of CTP. The tool was used to optimize and evaluate an in-house developed CTP-software algorithm. Imaging data of 103 acute stroke patients were included in the benchmarking tool. Median time from stroke onset to CT was 185 min (IQR 180-238), and the median time between completion of CT and start of MRI was 36 min (IQR 25-79). Volumetric accuracy of the CTP-ROIs was optimal at an rCBF threshold of <38%; at this threshold, the mean difference was 0.3 ml (SD 19.8 ml), the mean absolute difference was 14.3 (SD 13.7) ml, and CTP was 67% sensitive and 87% specific for identification of DWI positive tissue voxels. The benchmarking tool can play an important role in optimizing CTP software as it provides investigators with a novel method to directly compare the performance of alternative CTP software packages.
Even though stroke presents as a variety of clinical syndromes, neuroimaging is the most important biomarker to help differentiate between stroke subtypes and assess treatment eligibility. ...Therapeutic advances have led to intravenous thrombolysis with tissue-type plasminogen activator and endovascular treatment for proximal vessel occlusion in the anterior cerebral circulation being standard care for acute ischaemic stroke. Providing access to this care has implications for existing systems of care for stroke and their organisation and has reintroduced the possibility of adjuvant and neuroprotective treatment strategies in acute ischaemic stroke. The use of neuroimaging for patient selection and speed of diagnosis and delivery of treatment are the dominant themes of modern ischaemic stroke care.
In a randomized trial involving patients with acute stroke, the incidence of revascularization was higher with tenecteplase than with alteplase for intravenous thrombolysis before endovascular ...thrombectomy. Cerebral hemorrhage occurred at the same rate in each group.
CT perfusion (CTP) is widely and rapidly accessible for imaging acute ischemic stroke but has limited validation. Cerebral blood volume (CBV) has been proposed as the best predictor of infarct core. ...We tested CBV against other common CTP parameters using contemporaneous diffusion MRI.
Patients with acute ischemic stroke<6 hours after onset had CTP and diffusion MRI<1 hour apart, before any reperfusion therapies. CTP maps of time to peak (TTP), absolute and relative CBV, cerebral blood flow (CBF), mean transit time (MTT), and time to peak of the deconvolved tissue residue function (Tmax) were generated. The diffusion lesion was manually outlined to its maximal visual extent. Receiver operating characteristic (ROC) analysis area under the curve (AUC) was used to quantify the correspondence of each perfusion parameter to the coregistered diffusion-weighted imaging lesion. Optimal thresholds were determined (Youden index).
In analysis of 98 CTP slabs (54 patients, median onset to CT 190 minutes, median CT to MR 30 minutes), relative CBF performed best (AUC, 0.79; 95% CI, 0.77-81), significantly better than absolute CBV (AUC, 0.74; 95% CI, 0.73-0.76). The optimal threshold was <31% of mean contralateral CBF. Specificity was reduced by low CBF/CBV in noninfarcted white matter in cases with reduced contrast bolus intensity and leukoaraiosis.
In contrast to previous reports, CBF corresponded with the acute diffusion-weighted imaging lesion better than CBV, although no single threshold avoids detection of false-positive regions in unaffected white matter. This relates to low signal-to-noise ratio in CTP maps and emphasizes the need for optimized acquisition and postprocessing.
Summary Background Results of initial randomised trials of endovascular treatment for ischaemic stroke, published in 2013, were neutral but limited by the selection criteria used, early-generation ...devices with modest efficacy, non-consecutive enrolment, and treatment delays. Recent developments In the past year, six positive trials of endovascular thrombectomy for ischaemic stroke have provided level 1 evidence for improved patient outcome compared with standard care. In most patients, thrombectomy was performed in addition to thrombolysis with intravenous alteplase, but benefits were also reported in patients ineligible for alteplase treatment. Despite differences in the details of eligibility requirements, all these trials required proof of major vessel occlusion on non-invasive imaging and most used some imaging technique to exclude patients with a large area of irreversibly injured brain tissue. The results indicate that modern thrombectomy devices achieve faster and more complete reperfusion than do older devices, leading to improved clinical outcomes compared with intravenous alteplase alone. The number needed to treat to achieve one additional patient with independent functional outcome was in the range of 3·2–7·1 and, in most patients, was in addition to the substantial efficacy of intravenous alteplase. No major safety concerns were noted, with low rates of procedural complications and no increase in symptomatic intracerebral haemorrhage. Where next? Thrombectomy benefits patients across a range of ages and levels of clinical severity. A planned meta-analysis of individual patient data might clarify effects in under-represented subgroups, such as those with mild initial stroke severity or elderly patients. Imaging-based selection, used in some of the recent trials to exclude patients with large areas of irreversible brain injury, probably contributed to the proportion of patients with favourable outcomes. The challenge is how best to implement imaging in clinical practice to maximise benefit for the entire population and to avoid exclusion of patients with smaller yet clinically important potential to benefit. Although favourable imaging identifies patients who might benefit despite long delays from symptom onset to treatment, the proportion of patients with favourable imaging decreases with time. Health systems therefore need to be reorganised to deliver treatment as quickly as possible to maximise benefits. On the basis of available trial data, intravenous alteplase remains the initial treatment for all eligible patients within 4·5 h of stroke symptom onset. Those patients with major vessel occlusion should, in parallel, proceed to endovascular thrombectomy immediately rather than waiting for an assessment of response to alteplase, because minimising time to reperfusion is the ultimate aim of treatment.
BACKGROUND AND PURPOSE—In malignant infarction, brain edema leads to secondary neurological deterioration and poor outcome. We sought to determine whether swelling is associated with outcome in ...smaller volume strokes.
METHODS—Two research cohorts of acute stroke subjects with serial brain MRI were analyzed. The categorical presence of swelling and infarct growth was assessed on diffusion-weighted imaging (DWI) by comparing baseline and follow-up scans. The increase in stroke volume (ΔDWI) was then subdivided into swelling and infarct growth volumes using region-of-interest analysis. The relationship of these imaging markers with outcome was evaluated in univariable and multivariable regression.
RESULTS—The presence of swelling independently predicted worse outcome after adjustment for age, National Institutes of Health Stroke Scale, admission glucose, and baseline DWI volume (odds ratio, 4.55; 95% confidence interval, 1.21–18.9; P<0.02). Volumetric analysis confirmed that ΔDWI was associated with outcome (odds ratio, 4.29; 95% confidence interval, 2.00–11.5; P<0.001). After partitioning ΔDWI into swelling and infarct growth volumetrically, swelling remained an independent predictor of poor outcome (odds ratio, 1.09; 95% confidence interval, 1.03–1.17; P<0.005). Larger infarct growth was also associated with poor outcome (odds ratio, 7.05; 95% confidence interval, 1.04–143; P<0.045), although small infarct growth was not. The severity of cytotoxic injury measured on apparent diffusion coefficient maps was associated with swelling, whereas the perfusion deficit volume was associated with infarct growth.
CONCLUSIONS—Swelling and infarct growth each contribute to total stroke lesion growth in the days after stroke. Swelling is an independent predictor of poor outcome, with a brain swelling volume of ≥11 mL identified as the threshold with greatest sensitivity and specificity for predicting poor outcome.
PDF
