Intracranial thrombus extent predicts clinical outcome, final infarct size and hemorrhagic transformation in ischemic stroke: the clot burden score

Imaging-based selection in acute ischemic stroke trials - a quest for imaging sweet spots

Ischemic stroke is a very heterogeneous disease that limits the efficacy of acute stroke treatments. Future trials will require advanced imaging to select patients for specific treatments. The most well-established imaging tools are the use of CT to exclude hemorrhage and diffusion-weighted MRI to demonstrate ischemia. While perfusion imaging is one option for patient selection, it has unresolved issues, including standardization and validation, that limit its value. As an alternative to mismatch when addressing stroke, one needs to know the size of the initial irreversible lesion (core), the presence and site/extent of occlusion (clot), and presence of leptomeningeal back filling and Willisian filling (collaterals). These can be summarized as the "3C" approach of core, clot, and collateral interpretation, which together can represent an imaging sweet spot, particularly for time-efficient endovascular treatment trial design.

Future trials of endovascular mechanical recanalisation therapy in acute ischemic stroke patients - a position paper endorsed by ESMINT and ESNR : part II: methodology of future trials

Based on current data and experience, the joint working group of the European Society of Minimally Invasive Neurological Therapy (ESMINT) and the European Society of Neuroradiology (ESNR) make suggestions on trial design and conduct aimed to investigate therapeutic effects of mechanical thrombectomy (MT). We anticipate that this roadmap will facilitate the setting up and conduct of successful trials in close collaboration with our neighbouring disciplines.

Neuroimaging in acute stroke: choosing the right patient for neurointervention

Although the non-contrast computed tomography head continues as the sole mandatory imaging technique before intravenous thrombolysis, the increased availability of advanced infarct/penumbral imaging techniques and confidence in their use have led many to adopt them into routine practice--most particularly before intra-arterial interventions. Computed tomography versus magnetic resonance-based routes to imaging the cerebral vasculature, cell death, and parenchymal perfusion have differing advantages in terms of speed, availability, exposures to contrast and radiation, sensitivity, and resolution. Continued refinement and future developments, such as the ability to quantitate perfusion, promise to lead to tailored treatment protocols that respect the individual variations in anatomy, physiology, and pathology. This should lead both to an extension of treatment to patients currently excluded by rigid time windows and the avoidance of futile therapies and their associated morbidities.

Factors influencing clinically meaningful recanalization after IV-rtPA in acute ischemic stroke

BACKGROUND AND PURPOSE

Recanalization may not result in better clinical outcomes after ischemic stroke. We determined the incidence and significant predictors of CMR, defined as CT angiographic recanalization and a good clinical outcome, after IV-rtPA in acute ischemic stroke. A CMR score was devised and tested.

MATERIALS AND METHODS

One hundred twenty-six consecutive patients with anterior circulation ischemic stroke receiving IV-rtPA were retrospectively reviewed. Imaging included a baseline NCCT and CTA. Recanalization was assessed on a 24-hour CTA. Clinical outcome was determined by the 90-day mRS. CMR was defined as CTA recanalization and a good clinical outcome (mRS ≤2). Logistic regression analysis determined predictors of CMR. The predictive ability of a CMR score was tested with AIC.

RESULTS

CMR occurred in 29% (36/126). Patients with CMR had fewer neurologic deficits (P = .001) and higher ASPECTS (P = .041) at baseline than those without CMR. Baseline NIHSS score did not predict proximal occlusion (OR 0.959; 95% CI [0.907-1.014]; P = .141). Multivariate analysis showed admission NIHSS score (P = .001) and the site of vessel occlusion (P = .022) to be significant CMR predictors. CMR was significantly less likely in patients with proximal occlusions (ICA, P = .005; proximal M1, P = .021). A CMR score better predicted CMR than either NIHSS or vessel occlusion site alone (P < .0001).

CONCLUSIONS

Milder baseline stroke deficit and distal vessel occlusion are significant predictors of CMR. A combination of these parameters better predicts CMR than either parameter alone.

The mid-M1 segment of the middle cerebral artery is a cutoff clot location for good outcome in intravenous thrombolysis

BACKGROUND AND PURPOSE

We studied the impact of the location of the thrombus (internal carotid artery, proximal M1 segment, distal M1 segment, M2 segment, and M3 segment of the middle cerebral artery) in predicting the clinical outcome of patients treated with intravenous thrombolytic therapy (<3 h) in a retrospective cohort.

METHODS

Anterior circulation thrombus was detected with computed tomography angiography in 105 patients. Baseline clinical and radiological information was collected and entered into logistic regression analysis to predict favorable clinical outcome (3-month modified Rankin Scale from 0 to 2 was a primary outcome measure).

RESULTS

Three months after stroke, there was a significant increase in mortality (32% vs. 3%, P < 0.001) and functional dependency (82% vs. 29%, P < 0.001) in patients with internal carotid artery or proximal M1 segment of the middle cerebral artery thrombus compared to a more distal occlusion. In the regression analysis, after adjusting for National Institutes of Health Stroke Scale, age, sex, and onset-to-treatment time, the clot location was an independent predictor of good clinical outcome (P = 0.001) and exhibited dose-response type behavior when moving from a proximal vessel position to a more distal one. When the location was dichotomized, a cutoff between the proximal and the distal M1 segments best differentiated between good and poor clinical outcome (OR = 16.0, 95% CI 3.9-66.2).

CONCLUSIONS

The outcome of acute internal carotid artery or proximal M1 segment of the middle cerebral artery occlusion is generally poor even if treated with intravenous thrombolysis. Alternative revascularization strategies should be considered. Vascular imaging at the admission is required to guide this decision.

ASPECTS and other neuroimaging scores in the triage and prediction of outcome in acute stroke patients

Information obtained from brain imaging is now summarized in the form of various neuroimaging scores to help physicians in making therapeutic decisions and determining prognosis. The Alberta Stroke Program Early CT Score (ASPECTS) was devised to quantify the extent of early ischemic changes in the middle cerebral artery territory on noncontrast computed tomography. With its systematic approach, the score is simple, reliable, and a strong predictor of functional outcome. This review summarizes ASPECTS and other neuroimaging scores developed for risk prognostication and risk stratification with treatment in patients with acute ischemic stroke.

Admission CT perfusion is an independent predictor of hemorrhagic transformation in acute stroke with similar accuracy to DWI

BACKGROUND

The utility of admission CT perfusion (CTP) to that of diffusion-weighted imaging (DWI) as a predictor of hemorrhagic transformation (HT) in acute stroke was compared.

METHODS

We analyzed the admission CTP and DWI scans of 96 consecutive stroke patients. HT was present in 22 patients (23%). Infarct core was manually segmented on the admission DWI. We determined the: (1) hypoperfused tissue volume in the ischemic hemisphere using a range of thresholds applied to multiple different CTP parameter maps, and (2) mean relative CTP (rCTP) voxel values within both the DWI-segmented lesions and the thresholded CTP parameter maps. Receiver operating characteristic area under curve (AUC) analysis and multivariate regression were used to evaluate the test characteristics of each set of volumes and mean rCTP parameter values as predictors of HT.

RESULTS

The hypoperfused tissue volumes with either relative cerebral blood flow (rCBF) <0.48 (AUC = 0.73), or relative mean transit time (rMTT) >1.3 (AUC = 0.70), had similar accuracy to the DWI-segmented core volume (AUC = 0.68, p = 0.2 and p = 0.1, respectively) as predictors of HT. The mean rMTT voxel values within the rMTT >1.3 segmented lesion (AUC = 0.71) had similar accuracy to the mean rMTT voxel values (AUC = 0.65, p = 0.24) and mean rCBF voxel values (AUC = 0.64, p = 0.22) within the DWI-segmented lesion. The only independent predictors of HT were: (1) mean rMTT with rMTT >1.3, and (2) mechanical thrombectomy.

CONCLUSION

Admission CTP-based hypoperfused tissue volumes and thresholded mean voxel values are markers of HT in acute stroke, with similar accuracy to DWI. This could be of value when MRI cannot be obtained.

Preadmission therapeutic anticoagulation reduces cerebral infarct volume in patients with nonvalvular atrial fibrillation

AIM

We investigated the influence of preadmission anticoagulation on infarct volume in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

Data were collected on consecutive ischemic stroke patients with NVAF admitted to Osaka University Hospital between 2004 and 2011. Patients were divided into 3 groups: the no-anticoagulation group, the subtherapeutic anticoagulation group [admission prothrombin time international normalized ratio (PT-INR) <1.6], and the therapeutic anticoagulation group (PT-INR ≥1.6). In analyses of neurological outcome, we excluded patients with a modified Rankin Scale (mRS) score of >1 before onset.

RESULTS

Of the 68 patients, 45 were classified into the no-anticoagulation group, 9 into the subtherapeutic group, and 14 into the therapeutic group. The median value of infarct volume was 60 (interquartile range 9-176), 142 (64-184), and 8 (3-46) ml in each group, respectively. Infarct volume in the therapeutic group was significantly smaller than in the subtherapeutic group (p = 0.010), and tended to be smaller than in the no-anticoagulation group (p = 0.086). National Institute of Health Stroke Scale score at admission, and mRS score at discharge were significantly reduced in the therapeutic group compared with those in the other groups (p = 0.028 and p = 0.017, respectively).

CONCLUSION

Therapeutic anticoagulation reduces infarct volume and improves neurological outcome after ischemic stroke in patients with NVAF.

Regional leptomeningeal score on CT angiography predicts clinical and imaging outcomes in patients with acute anterior circulation occlusions

BACKGROUND AND PURPOSE

The regional leptomeningeal score is a strong and reliable imaging predictor of good clinical outcomes in acute anterior circulation ischemic strokes and can therefore be used for imaging based patient selection. Efforts to determine biological determinants of collateral status are needed if techniques to alter collateral behavior and extend time windows are to succeed.

MATERIALS AND METHODS

This was a retrospective Institutional Review Board-approved study of patients with acute ischemic stroke and M1 middle cerebral artery+/- intracranial internal carotid artery occlusion at our center from 2003 to 2009. The rLMC score is based on scoring pial and lenticulostriate arteries (0, no; 1, less; 2, equal or more prominent compared with matching region in opposite hemisphere) in 6 ASPECTS regions (M1-6) plus anterior cerebral artery region and basal ganglia. Pial arteries in the Sylvian sulcus are scored 0, 2, or 4. Good clinical outcome was defined as mRS ≤ 2 at 90 days.

RESULTS

The analysis included 138 patients: 37.6% had a good (17-20), 40.5% a medium (11-16), and 21.7% a poor (0-10) rLMC score. Interrater reliability was high, with an intraclass correlation coefficient of 0.87 (95% CI, 0.77%-0.95%). On univariate analysis, no single vascular risk factor was associated with the presence of poor rLMCs (P ≥ .20 for all comparisons). In multivariable analysis, the rLMC score (good versus poor: OR, 16.7; 95% CI, 2.9%-97.4%; medium versus poor: OR, 9.2, 95% CI, 1.7%-50.6%), age (< 80 years), baseline ASPECTS (≥ 8), and clot burden score (≥ 8) were independent predictors of good clinical outcome.

CONCLUSIONS

The rLMC score is a strong imaging parameter on CT angiography for predicting clinical outcomes in patients with acute ischemic strokes.

The clot burden score, the Boston Acute Stroke Imaging Scale, the cerebral blood volume ASPECTS, and two novel imaging parameters in the prediction of clinical outcome of ischemic stroke patients receiving intravenous thrombolytic therapy

INTRODUCTION

Recently two classification methods based on the location and the extent of thrombosis detected with CT angiography have been introduced: the Boston Acute Stroke Imaging Scale (BASIS) and the clot burden score (CBS). We studied the performance of BASIS and CBS in predicting good clinical outcome (mRS ≤ 2 at 90 days) in an acute (< 3 h) stroke cohort treated with intravenous thrombolytic therapy.

METHODS

Eighty-three consecutive patients who underwent multimodal CT were analyzed. Binary logistic regression model was used to assess how BASIS, CBS, and cerebral blood volume (CBV) ASPECTS predict favorable clinical outcome. Diagnostic sensitivities and specificities were calculated and compared.

RESULTS

Patients with low CBS and CBV ASPECTS scores and major strokes according to BASIS had significantly higher admission NIHSS scores, larger perfusion defects, and more often poor clinical outcome. In logistic regression analysis, CBV ASPECTS, CBS and BASIS were significantly associated with the clinical outcome. The performance of BASIS improved when patients with thrombosis of the M2 segment of the middle cerebral artery were classified as having minor stroke (M1-BASIS). In the anterior circulation, the sum of CBS and CBV ASPECTS (CBSV) proved to be the most robust predictor of favorable outcome. CBV ASPECTS and CBS had high sensitivity but moderate to poor specificity while BASIS was only moderately sensitive and specific.

CONCLUSION

CBS, BASIS, and CBV ASPECTS are statistically robust and sensitive but unspecific predictors of good clinical outcome. Two new derived imaging parameters, CBSV and M1-BASIS, share these properties and may have increased prognostic value.

Vascular imaging in stroke: comparative analysis

Advances in stroke treatment have mirrored advances in vascular imaging. Understanding and advances in reperfusion therapies were made possible by improvements in computed tomographic angiography, magnetic resonance angiography, neurovascular ultrasound, and renewed interest in catheter angiography. As technology allows better noninvasive vascular diagnosis, digital subtraction angiography (the remaining gold standard for vascular imaging) is increasingly used for rescue procedures and elective interventions. This review will examine specific advantages and disadvantages of different vascular imaging modalities as related to stroke diagnosis.

Intravenous flat-detector CT angiography in acute ischemic stroke management

INTRODUCTION

In the settings of stroke, a non-invasive high-resolution imaging modality to visualize the arterial intracranial circulation in the interventional lab is a helpful mean to plan the endovascular recanalization procedure. We report our initial experience with intravenously enhanced flat-detector CT (IV FDCT) technology in the detection of obstructed intracranial arteries.

METHODS

Fourteen consecutive patients elected for endovascular stroke therapy underwent IV FDCT. The scans were intravenously enhanced and acquired in accordance with the previously calculated bolus arrival time. Images were processed on a commercially available workstation for reconstructions and 3D manipulation. Occlusion level and clot length, the quality of collateral vessels, and the patency of anterior and posterior communicating arteries were assessed.

RESULTS

IV FDCT was performed successfully in all the cases and allowed for clot location and length visualization, assessment of communicating arteries patency, and evaluation of vessel collateral grade. Information obtained from this technique was considered useful for patients treated by endovascular approach. Retrospective review of the images by two independent readers was considered accurate and reproducible.

CONCLUSIONS

IV FDCT technology provided accurate delineation of obstructed vessel segments in acute ischemic stroke disease. It gave a significant help in the interventional strategy. This new technology available in the operating room might provide a valuable tool in emerging endovascular stroke therapy.

A smartphone client-server teleradiology system for primary diagnosis of acute stroke

Background

Recent advances in the treatment of acute ischemic stroke have made rapid acquisition, visualization, and interpretation of images a key factor for positive patient outcomes. We have developed a new teleradiology system based on a client-server architecture that enables rapid access to interactive advanced 2-D and 3-D visualization on a current generation smartphone device (Apple iPhone or iPod Touch, or an Android phone) without requiring patient image data to be stored on the device. Instead, a server loads and renders the patient images, then transmits a rendered frame to the remote device.

Objective

Our objective was to determine if a new smartphone client-server teleradiology system is capable of providing accuracies and interpretation times sufficient for diagnosis of acute stroke.

Methods

This was a retrospective study. We obtained 120 recent consecutive noncontrast computed tomography (NCCT) brain scans and 70 computed tomography angiogram (CTA) head scans from the Calgary Stroke Program database. Scans were read by two neuroradiologists, one on a medical diagnostic workstation and an iPod or iPhone (hereafter referred to as an iOS device) and the other only on an iOS device. NCCT brain scans were evaluated for early signs of infarction, which includes early parenchymal ischemic changes and dense vessel sign, and to exclude acute intraparenchymal hemorrhage and stroke mimics. CTA brain scans were evaluated for any intracranial vessel occlusion. The interpretations made on an iOS device were compared with those made at a workstation. The total interpretation times were recorded for both platforms. Interrater agreement was assessed. True positives, true negatives, false positives, and false negatives were obtained, and sensitivity, specificity, and accuracy of detecting the abnormalities on the iOS device were computed.

Results

The sensitivity, specificity, and accuracy of detecting intraparenchymal hemorrhage were 100% using the iOS device with a perfect interrater agreement (kappa = 1). The sensitivity, specificity, and accuracy of detecting acute parenchymal ischemic change were 94.1%, 100%, and 98.09% respectively for reader 1 and 97.05%, 100%, and 99.04% for reader 2 with nearly perfect interrater agreement (kappa = .8). The sensitivity, specificity, and accuracy of detecting dense vessel sign were 100%, 95.4%, and 96.19% respectively for reader 1 and 72.2%, 100%, and 95.23% for reader 2 using the iOS device with a good interrater agreement (kappa = .69). The sensitivity, specificity, and accuracy of detecting vessel occlusion on CT angiography scans were 94.4%, 100%, and 98.46% respectively for both readers using the iOS device, with perfect interrater agreement (kappa = 1). No significant difference (P < .05) was noted in the interpretation time between the workstation and iOS device.

Conclusion

The smartphone client-server teleradiology system appears promising and may have the potential to allow urgent management decisions in acute stroke. However, this study was retrospective, involved relatively few patient studies, and only two readers. Generalizing conclusions about its clinical utility, especially in other diagnostic use cases, should not be made until additional studies are performed.

The importance of size: successful recanalization by intravenous thrombolysis in acute anterior stroke depends on thrombus length

BACKGROUND AND PURPOSE

We hypothesize that in acute middle cerebral artery stroke, thrombus lengths measured in thin-slice nonenhanced CT images define a limit beyond which systemic thrombolysis will fail to recanalize occluded arteries.

METHODS

In 138 patients who presented with acute middle cerebral artery stroke and who were treated with intravenous thrombolysis (IVT), we measured lengths of thrombotic clots depicted as arterial hyperdensities in admission nonenhanced CT images with 2.5-mm slice width. Vascular recanalization was investigated after thrombolysis and recanalization results were related to thrombus lengths by logistic regression.

RESULTS

In 62 patients, IVT resulted in recanalization; among these patients, no thrombus length exceeded 8 mm. The median modified Rankin scale score at hospital discharge was 2. In the remaining 76 patients, thrombus lengths mostly exceeded 8 mm and IVT failed in recanalization. These patients were discharged with a median modified Rankin scale score of 5.

CONCLUSIONS

This study shows that in acute middle cerebral artery stroke, IVT has nearly no potential to recanalize occluded vessels if thrombus length exceeds 8 mm.

Effect of Baseline CT Scan Appearance and Time to Recanalization on Clinical Outcomes in Endovascular Thrombectomy of Acute Ischemic Strokes

Background and Purpose—

The Penumbra Pivotal Stroke Trial reported a 25% good outcome (modified Rankin scale score ≤2) despite an 81% recanalization rate. We evaluated the association of a favorable initial noncontrast CT and a short time to recanalization in predicting good outcome.

Methods—

Data were from the Penumbra Pivotal Stroke Trial. Baseline scans were evaluated by 2 experienced readers blinded to outcomes using ASPECTS. ASPECTS scores were dichotomized into >7 and ≤7 for primary analysis. Data on degree of recanalization based on thrombolysis in myocardial infarction scores, stroke onset to recanalization, and CT to recanalization times were obtained. Primary outcome was modified Rankin scale score ≤2 at 3 months.

Results—

Median baseline NIHSS was 18 (range, 8–34) and median baseline ASPECTS score was 6 (range, 0–10); 81.2% achieved recanalization (thrombolysis in myocardial infarction, 2–3) and (27.7%) achieved good outcome. Good outcome was significantly higher in the ASPECTS score >7 group when compared to the ASPECTS score ≤7 group (50% vs 15%; RR, 3.3; 95% CI, 1.6–6.8; P =0.0001). No patient with an ASPECTS score ≤4 (n=28) or without recanalization (n=16) had a good outcome. There was an interaction between baseline ASPECTS score (>7 and ≤7) and onset to recanalization time (≤300 minutes and >300 minutes) in predicting good outcome ( P =0.06).

Conclusion—

Patients with baseline CT ASPECTS score ≤4 do not benefit from recanalization. Fast recanalization may benefit patients with evident damage on the CT scan (ASPECTS score >4). Overall, patients benefit the most with early recanalization and a favorable baseline CT scan (ASPECTS score >7).

Low rates of acute recanalization with intravenous recombinant tissue plasminogen activator in ischemic stroke: real-world experience and a call for action

BACKGROUND AND PURPOSE

Acute rates of recanalization after intravenous (IV) recombinant tissue plasminogen activator (rt-PA) in proximal vessel occlusion have been estimated sparingly, typically using transcranial Doppler (TCD). We aimed to study acute recanalization rates of IV rt-PA in CT angiogram-proven proximal (internal carotid artery [ICA], M1 middle cerebral artery [MCA], M2-MCA, and basilar artery) occlusions and their effects on outcome.

MATERIALS AND METHODS

The CT angiogram database of the Calgary stroke program was reviewed for the period 2002 to 2009. All patients with proximal vessel occlusions receiving IV rt-PA who were assessed for recanalization by TCD or angiogram (for acute endovascular treatment) were included for analysis. Rates of acute recanalization as observed on TCD/first run of angiogram and postendovascular therapy recanalization rates were noted. Modified Rankin Scale score ≤2 at 3 months was used as a good outcome.

RESULTS

Among 1341 patients in the CT angiogram database, 388 patients with proximal occlusion were identified. Of these, 216 patients had received IV rt-PA; 127 patients underwent further imaging to assess recanalization. Among the patients undergoing TCD (n=46) and cerebral angiogram (n=103), only 27 (21.25%) patients had acute recanalization. By occlusion subtype, the rates of recanalization were: distal ICA (with or without ICA neck occlusion or stenotic disease) 1 of 24 (4.4%); M1-MCA (with or without ICA neck occlusion or stenotic disease) 21 of 65 (32.3%); M2-MCA 4 of 13 (30.8%); and basilar artery 1 of 25 (4%). Onset to rt-PA time was comparable in patients with and without recanalization. Recanalization (P<0.0001; risk ratio, 2.7; 95% confidence interval, 1.5-4.6) was the strongest predictor of outcome (adjusted for age and National Institutes of Health Stroke Scale score).

CONCLUSIONS

A low rate of acute recanalization was observed with IV rt-PA in proximal vessel occlusions identified by baseline CT angiogram. Recanalization was the strongest predictor of good outcome.

Assessment of Thrombus in Acute Middle Cerebral Artery Occlusion Using Thin-Slice Nonenhanced Computed Tomography Reconstructions

Background and Purpose— We sought to evaluate how accurately length and volume of thrombotic clots occluding cerebral arteries of patients with acute ischemic stroke can be assessed from nonenhanced CT (NECT) scans reconstructed with different slice widths.

Methods— NECT image data of 58 patients with acute ischemic stroke with vascular occlusion proven by CT angiography were reconstructed with slice widths of 1.25 mm, 2.5 mm, 3.75 mm, and 5 mm. Thrombus lengths and volumes were quantified based on these NECT images by detecting and segmenting intra-arterial hyperdensities. The results were compared with reference values of thrombus length and volume obtained from CT angiography images using Bland-Altman analysis and predefined levels or tolerance to find NECT slice thicknesses that allow for sufficiently accurate thrombus quantification.

Results— Thrombus length can be measured with high accuracy using the hyperdense middle cerebral artery sign detected in NECT images with slice thicknesses of 1.25 mm and 2.5 mm. We found mean deviations from the reference values and limits of agreement of −0.1 mm±0.6 mm with slice widths of 1.25 mm and 0.1 mm±0.7 mm for slice widths of 2.5 mm. Thrombus length measurements in NECT images with higher slice width and all evaluated thrombus volume measurements exhibited severe dependence on the level and did not match the accuracy criteria.

Conclusion— The length of the hyperdense middle cerebral artery sign as detected on thin-slice NECT reconstructions in patients with acute ischemic stroke can be used to quantify thrombotic burden accurately. Thus, it might qualify as a new diagnostic parameter in acute stroke management that indicates and quantifies the extent of vascular obliteration.

The benefits of intravenous thrombolysis relate to the site of baseline arterial occlusion in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET)

BACKGROUND AND PURPOSE

In ischemic stroke, the site of arterial obstruction has been shown to influence recanalization and clinical outcomes. However, this has not been studied in randomized controlled trials, nor has the impact of arterial obstruction site on reperfusion and infarct growth been assessed. We studied the influence of site and degree of arterial obstruction patients enrolled in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET).

METHODS

EPITHET was a prospective, randomized, placebo-controlled trial of intravenous tissue plasminogen activator (tPA) in the 3- to 6-hour time window. Arterial obstruction site and degree were rated on magnetic resonance angiography blinded to treatment allocation and outcomes.

RESULTS

In 101 EPITHET patients, 87 had adequate quality magnetic resonance angiography, of whom 54 had baseline arterial obstruction. Infarct growth attenuation was greater in those with tPA treatment compared to placebo among patients with middle cerebral artery (MCA) obstruction (P=0.037). The treatment benefit of tPA over placebo in attenuating infarct growth was greater for MCA than internal carotid artery (ICA) obstruction (P=0.060). With tPA treatment, good clinical outcome was more likely with MCA than with ICA obstruction (P=0.005). Most patients with ICA obstruction did not achieve good clinical outcome, whether treated with tPA (100%) or placebo (77%). The study was underpowered to prove any treatment benefit of tPA among patients with any or severe degree of arterial obstruction.

CONCLUSIONS

Arterial obstruction site strongly predicts outcomes. ICA obstruction carries a uniformly poor prognosis, whereas good outcomes with MCA obstruction are associated with tPA therapy.

The Alberta Stroke Program Early CT Score in Clinical Practice: What have We Learned?

The introduction of brain imaging with computed tomography revolutionised the treatment of patients with acute ischaemic stroke. With the visual differentiation of haemorrhagic stroke from ischaemic stroke, thrombolytic therapy became feasible. The Alberta Stroke Program Early CT Score was devised to quantify the extent of early ischaemic changes in the middle cerebral artery territory on noncontrast computed tomography. With its systematic approach, the score is simple and reliable. However, the assessment of early ischaemic changes and Alberta Stroke Program Early CT scoring require training. The Alberta Stroke Program Early CT Score is a strong predictor of functional outcome. Furthermore, the effectiveness of intraarterial thrombolysis in patients with middle cerebral artery occlusion shows effect modification by the Alberta Stroke Program Early CT Score. This review summarises the Alberta Stroke Program Early CT Score methodology. We illustrate current knowledge regarding Alberta Stroke Program Early CT Score applied to clinical trials and comment on how Alberta Stroke Program Early CT Score may facilitate clinical treatment decision making and future trial design. Moreover, we introduce a modification of the Alberta Stroke Program Early CT Score methodology that disregards isolated cortical swelling, i.e. focal brain swelling without associated parenchymal hypoattenuation, as early ischaemic changes in the Alberta Stroke Program Early CT Score system.

CT angiography clot burden score and collateral score: correlation with clinical and radiologic outcomes in acute middle cerebral artery infarct

BACKGROUND AND PURPOSE

Clot extent, location, and collateral integrity are important determinants of outcome in acute stroke. We hypothesized that a novel clot burden score (CBS) and collateral score (CS) are important determinants of clinical and radiologic outcomes and serve as useful additional stroke outcome predictors.

MATERIALS AND METHODS

One hundred twenty-one patients with anterior circulation infarct presenting within 3 hours of stroke onset were reviewed. The Spearman correlation was performed to assess the correlation between CBS and CS and clinical and radiologic outcome measures. Patients were dichotomized by using a 90-day modified Rankin scale (mRS) score. Uni- and multivariate logistic regression models were used to assess variables predicting favorable clinical and radiologic outcomes. Receiver operating characteristic and intraclass correlation coefficient (ICC) analyses were performed. Diagnostic performance of a CBS threshold of >6 was assessed.

RESULTS

There were 85 patients (mean age, 70 +/- 14.5 years). Patients with higher CBS and CS demonstrated smaller pretreatment perfusion defects and final infarct volume and better clinical outcome (all, P < .01). CBS (P = .009) and recanalization (P = .015) independently predicted favorable outcome. A CBS >6 predicted good clinical outcome with an area under the curve of 0.75 (95% confidence interval [CI], 0.65-0.84; P = .0001), sensitivity of 73.0 (95% CI, 55.9-86.2), and specificity of 64.6 (95% CI, 49.5-77.8). The recanalization rate with intravenous recombinant tissue plasminogen activator was higher in patients with CBS >6 (P = .04; odds ratio, 3.2; 95% CI, 1.1-9.4). The ICC was 0.97 (95% CI, 0.95-0.98) and 0.87 (95% CI, 0.80-0.91) for CBS and CS, respectively.

CONCLUSIONS

CBS and CS are useful additional markers predicting clinical and radiologic outcomes.

GABAergic mechanisms are involved in the antihyperalgesic effects of carbamazepine and oxcarbazepine in a rat model of inflammatory hyperalgesia

BACKGROUND/AIMS

The purpose of this study was to investigate the involvement of GABAergic mechanisms in the antihyperalgesic effect of carbamazepine and oxcarbazepine by examining the effect of bicuculline (GABA(A) receptor antagonist) on these effects of antiepileptic drugs.

METHODS

Rats were intraplantarly (i.pl.) injected with the proinflammatory compound concanavalin A (Con A). A paw-pressure test was used to determine: (1) the development of hyperalgesia induced by Con A; (2) the effects of carbamazepine/oxcarbazepine on Con A-induced hyperalgesia, and (3) the effects of bicuculline on the carbamazepine/oxcarbazepine antihyperalgesia.

RESULTS

Intraperitoneally injected bicuculline (0.5-1 mg/kg, i.p.) exhibited significant suppression of the systemic antihyperalgesic effects of carbamazepine (27 mg/kg, i.p.) and oxcarbazepine (80 mg/kg, i.p.). When applied intraplantarly, bicuculline (0.14 mg/paw, i.pl.) did not produce any change in the peripheral antihyperalgesic effects of carbamazepine (0.14 mg/paw, i.pl.) and oxcarbazepine (0.5 mg/paw, i.pl.). Bicuculline alone did not produce an intrinsic effect in the paw-pressure test.

CONCLUSION

These results indicate that the antihyperalgesic effects of carbamazepine and oxcarbazepine against inflammatory hyperalgesia involve in part the GABAergic inhibitory modulation of pain transmission at central, but not at peripheral sites, which is mediated via GABA(A) receptor activation.