This article has Open Peer Review reports available.
Oxfordshire community stroke project classification improves prediction of post-thrombolysis symptomatic intracerebral hemorrhage
© Sung et al.; licensee BioMed Central Ltd. 2014
Received: 2 December 2013
Accepted: 25 February 2014
Published: 1 March 2014
The Oxfordshire Community Stroke Project (OCSP) classification is a simple stroke classification system with value in predicting clinical outcomes. We investigated whether and how the addition of OCSP classification to the Safe Implementation of Thrombolysis in Stroke (SITS) symptomatic intracerebral hemorrhage (SICH) risk score improved the predictive performance.
We constructed an extended risk score by adding an OCSP component, which assigns 3 points for total anterior circulation infarcts, 0 point for partial anterior circulation infarcts or lacunar infarcts. Patients with posterior circulation infarcts were assigned an extended risk score of zero. We analyzed prospectively collected data from 4 hospitals to compare the predictive performance between the original and the extended scores, using area under the receiver operating characteristic curve (AUC) and net reclassification improvement (NRI).
In a total of 548 patients, the rates of SICH were 7.3% per the National Institute of Neurological Diseases and Stroke (NINDS) definition, 5.3% per the European-Australasian Cooperative Acute Stroke Study (ECASS) II, and 3.5% per the SITS-Monitoring Study (SITS-MOST). Both scores effectively predicted SICH across all three definitions. The extended score had a higher AUC for SICH per NINDS (0.704 versus 0.624, P = 0.015) and per ECASS II (0.703 versus 0.612, P = 0.016) compared with the SITS SICH risk score. NRI for the extended risk score was 22.3% (P = 0.011) for SICH per NINDS, 21.2% (P = 0.018) per ECASS II, and 24.5% (P = 0.024) per SITS-MOST.
Incorporation of the OCSP classification into the SITS SICH risk score improves risk prediction for post-thrombolysis SICH.
Thrombolytic therapy with intravenous tissue plasminogen activator (tPA) for acute ischemic stroke increases the risk of symptomatic intracerebral hemorrhage (SICH) . Factors associated with SICH include older age, higher baseline National Institutes of Health Stroke Scale (NIHSS) score, elevated blood glucose, prior antiplatelet use, presence of atrial fibrillation, congestive heart failure, renal impairment, and early ischemic changes on pretreatment brain imaging . Several risk score models incorporating these potential predictors have been constructed to determine the risk of tPA-associated SICH [3–9]. Although the discriminatory abilities of such models appear good, there may be room for further improvement.
Stroke territory may help estimate the risk of post-thrombolysis hemorrhagic transformation because posterior circulation stroke might be associated with a low risk of SICH [10, 11]. The concept was first implied in the Hemorrhage After Thrombolysis (HAT) score , in which the presence of hypodensity in middle cerebral artery territory on computed tomography (CT) denotes an anterior circulation stroke. No risk prediction models have yet explicitly incorporated stroke territory. However, using neuroimaging study to determine stroke territory may not be applicable or timely in emergency settings. Even magnetic resonance imaging (MRI) detected acute lesions in only 46% of patients with acute ischemic stroke examined within 3 hours after symptom onset .
The Oxfordshire Community Stroke Project (OCSP) classification, based on clinical syndromes alone, can predict the site and size of infarct on CT in patients with established or hyperacute ischemic stroke [13, 14]. In a previous study , we demonstrated that the OCSP classification could help evaluate the risk of post-thrombolysis SICH. We therefore examined whether and how the addition of the OCSP classification could improve current SICH risk scores.
We analyzed data pooled from 4 hospital-based stroke registries in Taiwan (National Cheng Kung University Hospital, Chi-Mei Medical Center, Chia-Yi Christian Hospital, and Landseed Hospital) . Consecutive stroke patients treated with intravenous tPA within 3 hours of symptom onset between January 2007 and June 2012 were identified. Eligibility for tPA treatment was determined following the guidelines of the American Heart Association , and included off-label use (age >80 or NIHSS score >25). Variable dosing in the range of 0.6 to 0.9 mg/kg is recommended according to the current Taiwan guidelines . Different treatment regimens were used in the study sites. At the Chi-Mei Medical Center and the Landseed Hospital, the dose was fixed at 0.9 mg/kg. At the Chia-Yi Christian Hospital, the dose was initially set at 0.9 mg/kg and was changed to 0.8 mg/kg after August 2010. At the National Cheng Kung University Hospital, the dose was initially set at 0.7 mg/kg and was altered to 0.9 mg/kg after July 2009. Stroke severity was assessed by the NIHSS at baseline and at discharge. All patients underwent CT or MRI between 24 and 36 hours after thrombolysis and additional scans in case of clinical deterioration. The official neuroradiology reports were used to determine the presence and size of visible hypodensity on initial head CT scan and the presence or absence of intracerebral hemorrhage (ICH) on follow-up scans. The study protocol was approved by the Landseed Institutional Review Board (IRB), National Cheng Kung University Hospital IRB, Chi-Mei Medical Center IRB, and Chia-Yi Christian Hospital IRB, respectively.
Research coordinators in each site extracted the parts of medical charts recording the neurological symptoms and signs before the administration of intravenous tPA. Two board-certified neurologists (CSW and LCH), who were blinded to neuroimaging findings and risk scores of each patient, independently examined the abstracted records and performed the clinical classification . Patients were classified as having total anterior circulation infarcts (TACI), partial anterior circulation infarcts (PACI), posterior circulation infarcts (POCI), or lacunar infarcts (LACI) based on their maximal neurological deficits before the initiation of thrombolytic therapy. Undetermined stroke syndrome was classified as “uncertain”. Discrepancies were resolved by including a third board-certified neurologist (YCH), or classified as uncertain when all three disagreed with each other.
Primary outcome was the occurrence of SICH following intravenous tPA treatment. Because SICH rates are subject to the definition of SICH, we applied three definitions. SICH per the National Institute of Neurological Diseases and Stroke (NINDS) is defined as any neurological worsening (NIHSS ≥1) within 36 hours of tPA administration that is attributed to ICH verified by CT or MRI . SICH per the European-Australasian Cooperative Acute Stroke Study (ECASS) II is defined as any type of ICH on any posttreatment imaging after the start of thrombolysis and a neurological deterioration of ≥4 points on the NIHSS from baseline, or from the lowest value within 7 days, or leading to death . SICH per the Safe Implementation of Thrombolysis in Stroke - Monitoring Study (SITS-MOST) is defined as a local or remote type 2 parenchymal hemorrhage on the 22- to 36-hour post-treatment CT scan associated with a neurological deterioration of ≥4 points on the NIHSS or leading to death .
Calculation of the risk score
Risk scoring systems of the SITS SICH risk score and the extended risk score
No. of points
SITS SICH risk score
Extended risk score
Aspirin + clopidogrel
Blood glucose ≥180 mg/dL
Age ≥72 y
Systolic blood pressure ≥146 mm Hg
Weight ≥95 kg
Onset-to-treatment time ≥180 min
History of hypertension
Total anterior circulation infarct
Maximal total points
We constructed an extended SITS SICH risk score (Table 1) by incorporating an OCSP classification component. In light of a finding that TACI increased sixfold the risk of SICH per ECASS II (after adjustment for age, glucose, and antiplatelet use before admission) , initially we assigned 3 points to TACI and 0 point to PACI or LACI in the OCSP classification component. Furthermore, considering the low risk of SICH in posterior circulation stroke [10, 11], patients with POCI were assigned an extended risk score of zero, irrespective of their original SITS SICH risk scores. After examining the discrimination ability of different weighting of TACI using the area under the receiver operating characteristic curve (AUC) (Additional file 1: Table S1), we eventually constructed the 15-point extended risk score as described above.
Continuous variables were summarized as mean ± SD or median (interquartile range), and categorical variables as counts and percentages. We performed separate univariate logistic regressions for the original and the extended risk score to determine the odds ratios per point increase of the score. The model fit was judged by the Hosmer–Lemeshow goodness-of-fit statistic. The discriminatory ability of the extended score was evaluated by the AUC, and compared using the DeLong method . Bootstrap resampling (1000 replicates) was used to estimate confidence intervals for the AUC.
We examined risk reclassification from strata of the SITS SICH risk score to those of the extended risk score by cross tabulation. For practical purposes, we stratified the SITS SICH risk score into 3 categories: low (0 to 2 points), average (3 to 5 points), and elevated risk (≥6 points). The same cutoffs were used in the SITS SICH risk score study , but we collapsed strata of 6 to 8 points and ≥9 points into one group. To align the thresholds for defining risk categories, the extended risk score was categorized into low (0 to 3 points), average (4 to 7 points), and elevated risk (≥8 points). We used the net reclassification improvement (NRI), calculated as [proportion of all SICH events reclassified at higher risk – proportion reclassified at lower risk] – [proportion of all nonevents reclassified at higher risk – proportion reclassified at lower risk] , to assess the incremental effect of adding the OCSP classification component. Two tailed P values <0.05 were considered statistically significant. Statistical analyses were performed using MedCalc 12.5.0 (MedCalc Software bvba, Ostend, Belgium) or Stata 11 (StataCorp, College Station, Texas).
Characteristics of the study patients
n = 548
Age, mean (SD)
Male, n (%)
Medical history, n (%)
Congestive heart failure
Baseline NIHSS score, median (IQR)
Body weight, mean (SD), kg
Systolic blood pressure, mean (SD), mm Hg
Glucose, mean (SD), mmol/L
Platelet count, mean (SD), ×109/L
Actual tPA dose, median (IQR), mg/kg
OTT, median (IQR), min
OCSP classification, n (%)
Comparison of prediction performance between the SITS SICH risk score and the extended risk score
Odds ratio (95% CI) per point
AUC (95% CI)
Difference between areas
Net reclassification improvement
SICH per NINDS
SITS SICH risk score
Extended risk score
SICH per ECASS II
SITS SICH risk score
Extended risk score
SICH per SITS-MOST
SITS SICH risk score
Extended risk score
We demonstrated that incorporation of the OCSP classification into the SITS SICH risk score significantly improved the performance in predicting SICH in our study population. The extended risk score reasonably predicted SICH across the three definitions with good calibration. A substantial proportion of patients without SICH were reclassified into lower risk category (NRI for these patients was about 14% across the three definitions of SICH). Overall, the extended risk score moved an additional 18% (37% minus 19%) of patients to the low risk category, and 46% (168 of 362) patients with average risk (3 to 5 points according to the SITS SICH risk score) were reclassified (Additional file 1: Table S3 to S5).
The improved discriminatory ability of the extended risk score is clinically useful and might facilitate thrombolytic treatment in acute ischemic stroke. Notably, many emergency physicians were unwilling to provide thrombolysis for acute ischemic stroke in fear of SICH . In Taiwan, perceived risk of SICH among emergency physicians, neurologists, and patients was a major barrier to implement thrombolytic treatment . Risk prediction models that could correctly identify patients at low SICH risk after thrombolysis are of great benefit to stroke patients because they help remove the psychological barriers to administering tPA.
Studies show that patients with posterior circulation stroke are unlikely to develop SICH or hemorrhagic transformations [10, 11]. Therefore in our study the patients with POCI were assigned an extended risk score of zero. A potential mechanism underlying the low incidence of SICH in posterior circulation stroke is the infrequent permeability derangements detected on pretreatment MRI . Permeability derangements, which indicate blood–brain barrier disruption in ischemic fields, increased the propensity for hemorrhagic transformation in stroke patients treated with either recanalization therapy or conservative care . Another possible mechanism is better collaterals in the territory of the posterior cerebral artery than that of the middle cerebral artery . Patients with good collateral circulation might be less vulnerable to SICH after recanalization therapy [29, 30]. Additionally, the size of ischemic brain tissue was associated with SICH after intravenous thrombolysis [31, 32]. The small lesion volume in infratentorial strokes as compared to supratentorial strokes might partly explain the low incidence of SICH in patients with POCI.
Because the volume of the affected brain tissue is generally correlated with clinical stroke severity, models for predicting post-thrombolysis SICH usually included the NIHSS or the less commonly used Canadian Neurological Scale as a predictor [3–9]. However, patients with right hemisphere strokes may have a low NIHSS score despite a substantial lesion volume . Consequently, patients with right hemisphere nonlacunar strokes would have a higher risk of post-thrombolysis hemorrhage than those with left hemisphere strokes and similar NIHSS scores . In contrast, the OCSP classification in the early hours of ischemic stroke correlated well with infarct size . Without the assessment bias between hemispheres, the OCSP classification complements the NIHSS score in predicting SICH risk.
Although the OCSP classification generally corresponded well to the radiological findings, the sensitivity and specificity were different among the four OCSP categories. Using lesion topography on diffusion-weighted MRI as the diagnostic standard, the likelihood of correct classification was low for PACI and LACI, whereas high for TACI and POCI . Therefore, we did not differentiate patients with PACI from those with LACI in designing the extended risk score. Theoretically, a prediction model combining imaging findings and clinical factors could improve the prediction of SICH. A recent study indicated that the blood Sugar, Early infarct signs, hyperDense cerebral artery sign, Age, and NIHSS (SEDAN) score  had the highest predictive power among the existing risk prediction scores . Our previous study also found that the HAT score performed well . However, the interpretation of early infarct signs or hyperdense cerebral artery sign requires considerable radiological expertise, which may not be feasible in settings where neuroradiologists are not available on a 24/7 basis . In addition to indicating an anterior circulation infarct, the appearance of early infarct signs on CT also hints at longer elapsed time since stroke onset . The inclusion of total anterior circulation infarct and the onset-to-treatment time, which is a component of the SITS SICH risk score, in our revised risk score offers a clinical counterpart to the radiological findings of early infarct signs. Although the SITS SICH risk score in conjunction with the OCSP classification seems more complex, it provides an alternative when the local radiological expertise is limited. In particular, the OCSP classification could be easily and reliably determined using a standard symptom list .
Methods of model assessment should depend on the intended use of the model. Intravenous thrombolysis should not be withheld for an otherwise eligible patient simply because of high anticipated risk of SICH. The demonstrated improvement in classification performance in the extended risk score should be used only to better comprehend the risk associated with thrombolytic therapy. In particular, reclassification performance is sensitive to the number of clinically relevant risk categories, and the OCSP classification renders applying the risk scores largely unnecessary in patients with POCI.
Awareness of the applications and potential limitations of the risk scores will aid the clinicians in daily clinical decision making. Patients and their family could be better informed of the risk of SICH before making a shared treatment decision with their physicians. Those at high risk of SICH may benefit from more intensive monitoring, such as blood pressure and blood glucose. Another potential use of the risk scores is for case-mix adjustment in light of the fact that post-thrombolysis SICH might be used to measure performance of acute stroke care .
Our study has limitations. First, the OCSP syndromes were assessed based on medical records, rather than personal examination. Although the interrater agreement in the clinical classification of syndromes was moderate, the accuracy of classification might be compromised. Further studies with prospective OCSP classification are needed to confirm the clinical implications of our findings. Second, the number of SICH events was small, which precluded multivariable analyses, such as reweighting the predictors of the SITS SICH risk score. The limited number of events might also explain the failure to show superior discrimination (higher AUC) of the extended risk score in predicting SICH per the SITS-MOST definition. Third, a proportion of our patients were treated with a lower dose of intravenous tPA. Whether the prediction performance of risk models is subject to dosage remains to be explored. Finally, our study should be viewed as hypothesis generating. Potential patient selection bias could impact the model performance. Further validation is needed to strengthen generalizability of our findings.
Incorporating the OCSP classification of stroke syndromes to the SITS SICH risk score could improve the risk prediction for post-thrombolysis SICH. Further studies to evaluate the performance of the extended risk score on large cohorts are warranted.
The authors thank Mei-Hung Hou, Yu-Ru Chen, Pei-Yu Su, Ju-Fang Yang and Dr. Han-Chieh Hsieh for their efforts in acquisition of data and generous assistance.
- The National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group: Tissue plasminogen activator for acute ischemic stroke. N Engl J Med. 1995, 333: 1581-1587.View ArticleGoogle Scholar
- Whiteley WN, Slot KB, Fernandes P, Sandercock P, Wardlaw J: Risk factors for intracranial hemorrhage in acute ischemic stroke patients treated with recombinant tissue plasminogen activator: a systematic review and meta-analysis of 55 studies. Stroke. 2012, 43: 2904-2909. 10.1161/STROKEAHA.112.665331.View ArticlePubMedGoogle Scholar
- Cucchiara B, Tanne D, Levine SR, Demchuk AM, Kasner S: A risk score to predict intracranial hemorrhage after recombinant tissue plasminogen activator for acute ischemic stroke. J Stroke Cerebrovasc Dis. 2008, 17: 331-333. 10.1016/j.jstrokecerebrovasdis.2008.03.012.View ArticlePubMedGoogle Scholar
- Lou M, Safdar A, Mehdiratta M, Kumar S, Schlaug G, Caplan L, Searls D, Selim M: The HAT Score: a simple grading scale for predicting hemorrhage after thrombolysis. Neurology. 2008, 71: 1417-1423. 10.1212/01.wnl.0000330297.58334.dd.View ArticlePubMedPubMed CentralGoogle Scholar
- Saposnik G, Fang J, Kapral MK, Tu JV, Mamdani M, Austin P, Johnston SC, Investigators of the Registry of the Canadian Stroke Network (RCSN): The iScore predicts effectiveness of thrombolytic therapy for acute ischemic stroke. Stroke. 2012, 43: 1315-1322. 10.1161/STROKEAHA.111.646265.View ArticlePubMedGoogle Scholar
- Strbian D, Engelter S, Michel P, Meretoja A, Sekoranja L, Ahlhelm FJ, Mustanoja S, Kuzmanovic I, Sairanen T, Forss N, Cordier M, Lyrer P, Kaste M, Tatlisumak T: Symptomatic intracranial hemorrhage after stroke thrombolysis: the SEDAN score. Ann Neurol. 2012, 71: 634-641. 10.1002/ana.23546.View ArticlePubMedGoogle Scholar
- Mazya M, Egido JA, Ford GA, Lees KR, Mikulik R, Toni D, Wahlgren N, Ahmed N, for the SITS Investigators: Predicting the risk of symptomatic intracerebral hemorrhage in ischemic stroke treated with intravenous alteplase: safe implementation of treatments in stroke (SITS) symptomatic intracerebral hemorrhage risk score. Stroke. 2012, 43: 1524-1531. 10.1161/STROKEAHA.111.644815.View ArticlePubMedGoogle Scholar
- Menon BK, Saver JL, Prabhakaran S, Reeves M, Liang L, Olson DM, Peterson ED, Hernandez AF, Fonarow GC, Schwamm LH, Smith EE: Risk score for intracranial hemorrhage in patients with acute ischemic stroke treated with intravenous tissue-type plasminogen activator. Stroke. 2012, 43: 2293-2299. 10.1161/STROKEAHA.112.660415.View ArticlePubMedGoogle Scholar
- Saposnik G, Guzik AK, Reeves M, Ovbiagele B, Johnston SC: Stroke prognostication using age and NIH stroke scale: SPAN-100. Neurology. 2013, 80: 21-28. 10.1212/WNL.0b013e31827b1ace.View ArticlePubMedPubMed CentralGoogle Scholar
- Pagola J, Ribo M, Alvarez-Sabín J, Rubiera M, Santamarina E, Maisterra O, Delgado-Mederos R, Ortega G, Quintana M, Molina CA: Thrombolysis in anterior versus posterior circulation strokes: timing of recanalization, ischemic tolerance, and other differences. J Neuroimaging. 2011, 21: 108-112. 10.1111/j.1552-6569.2009.00462.x.View ArticlePubMedGoogle Scholar
- Sarikaya H, Arnold M, Engelter ST, Lyrer PA, Mattle HP, Georgiadis D, Bonati LH, Fluri F, Fischer U, Findling O, Ballinari P, Baumgartner RW: Outcomes of intravenous thrombolysis in posterior versus anterior circulation stroke. Stroke. 2011, 42: 2498-2502. 10.1161/STROKEAHA.110.607614.View ArticlePubMedGoogle Scholar
- Chalela JA, Kidwell CS, Nentwich LM, Luby M, Butman JA, Demchuk AM, Hill MD, Patronas N, Latour L, Warach S: Magnetic resonance imaging and computed tomography in emergency assessment of patients with suspected acute stroke: a prospective comparison. Lancet. 2007, 369: 293-298. 10.1016/S0140-6736(07)60151-2.View ArticlePubMedPubMed CentralGoogle Scholar
- Mead GE, Lewis SC, Wardlaw JM, Dennis MS, Warlow CP: How well does the Oxfordshire community stroke project classification predict the site and size of the infarct on brain imaging?. J Neurol Neurosurg Psychiatr. 2000, 68: 558-562. 10.1136/jnnp.68.5.558.View ArticlePubMedPubMed CentralGoogle Scholar
- Kobayashi A, Wardlaw JM, Lindley RI, Lewis SC, Sandercock PAG, Czlonkowska A, IST-3 Collaborative Group: Oxfordshire community stroke project clinical stroke syndrome and appearances of tissue and vascular lesions on pretreatment CT in hyperacute ischemic stroke among the first 510 patients in the Third International Stroke Trial (IST-3). Stroke. 2009, 40: 743-748. 10.1161/STROKEAHA.108.526772.View ArticlePubMedGoogle Scholar
- Sung SF, Wu CS, Hsu YC, Tseng MC, Chen YW: Oxfordshire community stroke project classification but not NIHSS predicts symptomatic intracerebral hemorrhage following thrombolysis. J Neurol Sci. 2013, 324: 65-69. 10.1016/j.jns.2012.10.003.View ArticlePubMedGoogle Scholar
- Sung SF, Chen SCC, Lin HJ, Chen YW, Tseng MC, Chen CH: Comparison of risk-scoring systems in predicting symptomatic intracerebral hemorrhage after intravenous thrombolysis. Stroke. 2013, 44: 1561-1566. 10.1161/STROKEAHA.111.000651.View ArticlePubMedGoogle Scholar
- Adams HP, del Zoppo G, Alberts MJ, Bhatt DL, Brass L, Furlan A, Grubb RL, Higashida RT, Jauch EC, Kidwell C, Lyden PD, Morgenstern LB, Qureshi AI, Rosenwasser RH, Scott PA, Wijdicks EFM, American Heart Association: Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: the American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists. Stroke. 2007, 38: 1655-1711. 10.1161/STROKEAHA.107.181486.View ArticlePubMedGoogle Scholar
- Hu HH: Taiwan Guidelines for the Management of Stroke 2008. 2008, Taipei: Taiwan Stroke Society, 1Google Scholar
- Bamford J, Sandercock P, Dennis M, Burn J, Warlow C: Classification and natural history of clinically identifiable subtypes of cerebral infarction. Lancet. 1991, 337: 1521-1526. 10.1016/0140-6736(91)93206-O.View ArticlePubMedGoogle Scholar
- Hacke W, Kaste M, Fieschi C, von Kummer R, Davalos A, Meier D, Larrue V, Bluhmki E, Davis S, Donnan G, Schneider D, Diez-Tejedor E, Trouillas P: Randomised double-blind placebo-controlled trial of thrombolytic therapy with intravenous alteplase in acute ischaemic stroke (ECASS II). Second European-Australasian Acute Stroke Study Investigators. Lancet. 1998, 352: 1245-1251. 10.1016/S0140-6736(98)08020-9.View ArticlePubMedGoogle Scholar
- Wahlgren N, Ahmed N, Dávalos A, Ford GA, Grond M, Hacke W, Hennerici MG, Kaste M, Kuelkens S, Larrue V, Lees KR, Roine RO, Soinne L, Toni D, Vanhooren G, SITS-MOST investigators: Thrombolysis with alteplase for acute ischaemic stroke in the safe implementation of thrombolysis in stroke-monitoring study (SITS-MOST): an observational study. Lancet. 2007, 369: 275-282. 10.1016/S0140-6736(07)60149-4.View ArticlePubMedGoogle Scholar
- DeLong ER, DeLong DM, Clarke-Pearson DL: Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics. 1988, 44: 837-845. 10.2307/2531595.View ArticlePubMedGoogle Scholar
- Pencina MJ, D’Agostino RB, D’Agostino RB, Vasan RS: Evaluating the added predictive ability of a new marker: from area under the ROC curve to reclassification and beyond. Stat Med. 2008, 27: 157-172. 10.1002/sim.2929.View ArticlePubMedGoogle Scholar
- Brown DL, Barsan WG, Lisabeth LD, Gallery ME, Morgenstern LB: Survey of emergency physicians about recombinant tissue plasminogen activator for acute ischemic stroke. Ann Emerg Med. 2005, 46: 56-60.View ArticlePubMedGoogle Scholar
- Huang P, Khor GT, Chen CH, Lin RT, Liu CK: Eligibility and rate of treatment for recombinant tissue plasminogen activator in acute ischemic stroke using different criteria. Acad Emerg Med. 2011, 18: 273-278. 10.1111/j.1553-2712.2011.01006.x.View ArticlePubMedGoogle Scholar
- Lee M, Saver JL, Alger JR, Hao Q, Starkman S, Ali LK, Kim D, Ovbiagele B, Vespa PM, Froehler MT, Tenser MS, Salamon N, Villablanca JP, Jahan R, Duckwiler GR, Tateshima S, Gonzalez N, Vinuela F, Liebeskind DS: Blood–brain barrier permeability derangements in posterior circulation ischemic stroke: frequency and relation to hemorrhagic transformation. J Neurol Sci. 2012, 313: 142-146. 10.1016/j.jns.2011.08.048.View ArticlePubMedGoogle Scholar
- Bang OY, Saver JL, Alger JR, Shah SH, Buck BH, Starkman S, Ovbiagele B, Liebeskind DS, UCLA MRI Permeability Investigators: Patterns and predictors of blood–brain barrier permeability derangements in acute ischemic stroke. Stroke. 2009, 40: 454-461. 10.1161/STROKEAHA.108.522847.View ArticlePubMedGoogle Scholar
- Menon BK, O’Brien B, Bivard A, Spratt NJ, Demchuk AM, Miteff F, Lu X, Levi C, Parsons MW: Assessment of leptomeningeal collaterals using dynamic CT angiography in patients with acute ischemic stroke. J Cereb Blood Flow Metab. 2013, 33: 365-371. 10.1038/jcbfm.2012.171.View ArticlePubMedGoogle Scholar
- Bang OY, Saver JL, Kim SJ, Kim GM, Chung CS, Ovbiagele B, Lee KH, Liebeskind DS, UCLA-Samsung Stroke Collaborators: Collateral flow averts hemorrhagic transformation after endovascular therapy for acute ischemic stroke. Stroke. 2011, 42: 2235-2239. 10.1161/STROKEAHA.110.604603.View ArticlePubMedGoogle Scholar
- Chuang YM, Chan L, Lai YJ, Kuo KH, Chiou YH, Huang LW, Kwok YT, Lai TH, Lee SP, Wu HM, Yeh YC: Configuration of the circle of Willis is associated with less symptomatic intracerebral hemorrhage in ischemic stroke patients treated with intravenous thrombolysis. J Crit Care. 2013, 28: 166-172. 10.1016/j.jcrc.2012.08.018.View ArticlePubMedGoogle Scholar
- Dzialowski I, Hill MD, Coutts SB, Demchuk AM, Kent DM, Wunderlich O, Von Kummer R: Extent of early ischemic changes on computed tomography (CT) before thrombolysis: prognostic value of the Alberta stroke program early CT score in ECASS II. Stroke. 2006, 37: 973-978. 10.1161/01.STR.0000206215.62441.56.View ArticlePubMedGoogle Scholar
- Singer OC, Humpich MC, Fiehler J, Albers GW, Lansberg MG, Kastrup A, Rovira A, Liebeskind DS, Gass A, Rosso C, Derex L, Kim JS, Neumann-Haefelin T, MR Stroke Study Group Investigators: Risk for symptomatic intracerebral hemorrhage after thrombolysis assessed by diffusion-weighted magnetic resonance imaging. Ann Neurol. 2008, 63: 52-60. 10.1002/ana.21222.View ArticlePubMedGoogle Scholar
- Fink JN, Selim MH, Kumar S, Silver B, Linfante I, Caplan LR, Schlaug G: Is the association of National Institutes of Health Stroke Scale scores and acute magnetic resonance imaging stroke volume equal for patients with right- and left-hemisphere ischemic stroke?. Stroke. 2002, 33: 954-958. 10.1161/01.STR.0000013069.24300.1D.View ArticlePubMedGoogle Scholar
- Audebert HJ, Singer OC, Gotzler B, Vatankhah B, Boy S, Fiehler J, Lansberg MG, Albers GW, Kastrup A, Rovira A, Gass A, Rosso C, Derex L, Kim JS, Heuschmann P: Postthrombolysis hemorrhage risk is affected by stroke assessment bias between hemispheres. Neurology. 2011, 76: 629-636. 10.1212/WNL.0b013e31820ce505.View ArticlePubMedPubMed CentralGoogle Scholar
- Asdaghi N, Jeerakathil T, Hameed B, Saini M, McCombe JA, Shuaib A, Emery D, Butcher K: Oxfordshire community stroke project classification poorly differentiates small cortical and subcortical infarcts. Stroke. 2011, 42: 2143-2148. 10.1161/STROKEAHA.111.613752.View ArticlePubMedGoogle Scholar
- Strbian D, Michel P, Seiffge DJ, Saver JL, Numminen H, Meretoja A, Murao K, Weder B, Forss N, Parkkila AK, Eskandari A, Cordonnier C, Davis SM, Engelter ST, Tatlisumak T: Symptomatic intracranial hemorrhage after atroke thrombolysis: comparison of prediction scores. Stroke. 2014, 45: 752-758. 10.1161/STROKEAHA.113.003806.View ArticlePubMedGoogle Scholar
- Kalafut MA, Schriger DL, Saver JL, Starkman S: Detection of early CT signs of >1/3 middle cerebral artery infarctions: interrater reliability and sensitivity of CT interpretation by physicians involved in acute stroke care. Stroke. 2000, 31: 1667-1671. 10.1161/01.STR.31.7.1667.View ArticlePubMedGoogle Scholar
- von Kummer R, Meyding-Lamadé U, Forsting M, Rosin L, Rieke K, Hacke W, Sartor K: Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk. AJNR Am J Neuroradiol. 1994, 15: 9-15.PubMedGoogle Scholar
- Aerden L, Luijckx GJ, Ricci S, Hilton A, Kessels F, Lodder J: Validation of the Oxfordshire community stroke project syndrome diagnosis derived from a standard symptom list in acute stroke. J Neurol Sci. 2004, 220: 55-58. 10.1016/j.jns.2004.02.001.View ArticlePubMedGoogle Scholar
- Canadian Best Practice Recommendations for Stroke Care: Canadian Best Practice Recommendations for Stroke Care. [http://strokebestpractices.ca/wp-content/uploads/2013/05/Ch3_SBP2013_Hyper-Acute-_23MAY13_EN_-FINAL4.pdf]
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2377/14/39/prepub
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.