Validity and reliability of a quantitative computed tomography score in predicting outcome of hyperacute stroke before thrombolytic therapy. ASPECTS Study Group. Alberta Stroke Programme Early CT Score

Correction of symptomatic cerebral malperfusion due to acute type I aortic dissection by transcarotid stenting of the innominate and carotid arteries

INTRODUCTION

Acute proximal aortic dissection may be complicated by stroke due to malperfusion of the arch vessels. We report a novel case of successful endovascular treatment of acute cerebral malperfusion due to a dissection involving the aortic arch.

CASE REPORT

A 66 year old man was transferred from another hospital with an acute type I aortic dissection and underwent emergent repair of the aortic valve and ascending aorta with a composite graft. Left hemiplegia and altered cognitive function were noted on postoperative day 1. A carotid duplex scan showed partial thrombosis of the right carotid artery with very slow flow and reversal of flow in the right vertebral artery. A head CT was normal, while a head MRI and MR angiogram showed intraluminal defects in the inominate and right carotid arteries and perfusion abnormality of the entire right middle cerebral artery territory, but only small infarcts of watershed areas. The patient underwent stenting of the right carotid and inominate arteries through the right carotid artery with complete resolution of a large pressure gradient that was noted prior to stenting. The patient's left hemiplegia and cognitive impairment subsequently resolved during his inpatient hospitalization. On follow up five months later, he had a normal neurologic exam and MRI showed old watershed infarcts but no perfusion abnormality. On most recent follow-up 2.5 years after treatment, he remains well and a CT angiogram shows that his stented vessels remain patent.

CONCLUSION

Endovascular techniques may be safely applied to correct cerebral malperfusion that results from type I aortic dissection.

ENOS Trial Investigators. Glyceryl trinitrate vs. control, and continuing vs. stopping temporarily prior antihypertensive therapy, in acute stroke: rationale and design of the Efficacy of Nitric Oxide in Stroke (ENOS) trial (ISRCTN99414122)

High blood pressure (BP) is common in acute stroke and is independently associated with a poor outcome. Many patients with acute stroke are taking antihypertensive medications. To test the safety and efficacy of 7 days of transdermal glyceryl trinitrate (GTN, 5 mg/day) vs. no GTN in patients with acute stroke; patients taking antihypertensive therapy immediately before their stroke are also randomised to continue vs. stop this temporarily. ENOS is a prospective international multicentre single-blind randomised-controlled trial in 5000 patients with acute (<48 h of onset) ischaemic or haemorrhagic stroke. The primary outcome is combined death and dependency (modified Rankin scale >2) at 90 days measured by blinded central telephone follow-up. Secondary outcomes include: BP over the 7 days of treatment; death, impairment (Scandinavian stroke scale), recurrence, and neuroimaging at 7 days; discharge disposition, disability (Barthel index), cognition (mini-mental status examination) and quality of life (EuroQoL). The sample size will allow an absolute difference in death/dependency of 5% to be detected with 90% power at 5% significance for GTN versus no GTN. Randomisation and data collection are performed over a secure Internet site with real-time data validation. Neuroimaging and serious adverse events are adjudicated blinded to treatment.

Utilisation du rt-PA intraveineux dans l’ischémie cérébrale en Centre Hospitalier Général : l’expérience de l’Hôpital Saint-Jean de Perpignan

INTRODUCTION

Intravenous recombinant tissue plasminogen activator (rt-PA) has approval for use despite of its authorization for treatment of ischemic stroke within the 3-hour time window in 2003, is rarely used in community hospital (CH). It therefore remains questionable if the positive results of the key studies conducted in specialized centers may be extended to community hospitals less specialized in the management of stroke.

METHODS

We report the results of an observational cohort study including 39 patients treated with intravenous rt-Pa (according to the NINDS rt-PA stroke trail treatment protocol) at St Jean Hospital (Perpignan, France) between March 1, 2002 and August 31, 2005. Results are compared to those of the treated arm of the NINDS study.

RESULTS

1.2p.cent of ischemic stroke were treated with intravenous rt-Pa. Results are similar to those of the NINDS study: The outcome was favorable (modified Rankin score (mRS) with 0 or 1) for 44p.cent of the patients (as compared to 39p.cent in the NINDS study (X2 = 0.34; p = 0.5)) and there was no significant difference in term of death or outcome as assessed by mRS at 3 months (X2 = 0.09; p = 0.75 and X2 = 0.77; p = 0.75, respectively). No symptomatic hemmorrhagic transformation related to the use of rt-Pa was observed.

CONCLUSION

Our results indicate that rt-PA therapy for ischemic stroke may be as safe and effective in the setting of a community hospital as it is in specialized centers.

Prognostic relevance of ultra-early doppler sonography in acute ischaemic stroke: a prospective multicentre study

BACKGROUND

Ischaemic stroke can result from a temporary or permanent occlusion of intracranial arteries. In the hyperacute stage of the disease cerebrovascular ultrasound can be used to determine the vascular pathology, but the significance of very early findings on ultrasound is unclear. The present study aimed to assess the prognostic value of doppler ultrasonography within the first hours after stroke for functional outcome.

METHODS

In a prospective multicentre design, patients with clinical signs of ischaemic anterior-circulation stroke were examined by doppler ultrasonography of the intracranial and extracranial arteries. Patients were separated into three groups according to the findings: normal middle-cerebral artery (MCA); branch occlusions; or a main-stem occlusion. The primary endpoint was functional outcome at 3 months. Logistic regression was used to test the association between the ultrasound diagnosis and functional outcome.

RESULTS

361 patients were identified with moderate to severe clinical deficits (National Institutes of Health Stroke Scale score 5-25). Of these, 121 (34%) had a normal MCA, 176 (48%) had branch occlusions, 7 (2%) had severe MCA stenosis, and 57 (16%) had a main-stem occlusion. 50 of the 57 (88%) patients with main-stem occlusion were dead or dependent 3 months after stroke. An occlusion of the main stem of the MCA within 6 h after stroke was an independent predictor for poor outcome (p=0.0006). 50% of patients with ultrasonographic diagnosis of branch occlusions and 63% with normal MCA had a good outcome. Combination of CT scan without early signs of infarction and a normal MCA resulted in a predictive value of 71% for a good functional outcome.

INTERPRETATION

Cerebrovascular ultrasonography provides additional functional prognostic information in the hyperacute stage of ischaemic stroke. The technique is practical in a well-resourced unit, can be used to identify patients with high risk for poor functional outcome, and thus would be an appropriate investigation for future trials.

Imaging of acute stroke

Thrombolytic therapy has led to a higher proportion of patients presenting to hospital early, and this, with parallel developments in imaging technology, has greatly improved the understanding of acute stroke pathophysiology. Additionally, MRI, including diffusion-weighted imaging (DWI) and gradient echo, or T2*, imaging is important in understanding basic structural information--such as distinguishing acute ischaemia from haemorrhage. It has also greatly increased sensitivity in the diagnosis of acute cerebral ischaemia. The pathophysiology of the ischaemic penumbra can now be assessed with CT or MRI-based perfusion imaging techniques, which are widely available and clinically applicable. Pathophysiological information from CT or MRI increasingly helps clinical trial design, may allow targeted therapy in individual patients, and may extend the time scale for reperfusion therapy.

Reduced pretreatment ipsilateral middle cerebral artery cerebral blood flow is predictive of symptomatic hemorrhage post-intra-arterial thrombolysis in patients with middle cerebral artery occlusion

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) can be a devastating complication associated with thrombolytic therapy for acute ischemic stroke. We hypothesized that patients with lower prethrombolysis cerebral blood flow (CBF) were at a higher risk of symptomatic ICH (sICH).

METHODS

Twenty-three patients who underwent quantitative CBF assessment with Xenon CT studies for acute stroke before intra-arterial (IA) thrombolysis for a middle cerebral artery (MCA) or internal carotid artery terminus occlusion within 6 hours of symptom onset were studied. Univariate and multivariate analysis were carried out to determine predictors of sICH post-IA thrombolysis. Receiver operating characteristic curves were generated to determine the association between mean ipsilateral CBF and the occurrence of sICH.

RESULTS

The mean age of our cohort was 68+/-12 years and a mean National Institutes of Health Stroke Scale (NIHSS) score of 18+/-3. In univariate analysis, patients with higher percent of core infarct, hyperglycemia, and reduced mean ipsilateral CBF were at risk of sICH. In multivariate analysis only mean ipsilateral CBF was associated with higher rates of sICH (odds ratio 1.58; 95% CI, 1.01 to 2.51; P<0.04). The area under the receiver operating characteristic curve was 0.87 (95% CI, 0.76 to 0.97; P<0.005).

CONCLUSIONS

Patients with lower pre-IA thrombolysis mean ipsilateral MCA CBF are at significantly higher risk for sICH in the setting of a MCA or carotid terminus occlusion. The threshold identified in this study may be useful for selection of patients with acute MCA occlusions for acute stroke thrombolysis.

How well does ASPECTS predict the outcome of acute stroke treated with IV tPA?

The authors measured the association of early ischemic change on CT scan, measured using the Alberta Stroke Programme Early CT score (ASPECTS), and functional outcome in 825 patients with anterior circulation stroke treated with IV thrombolysis within 3 hours of onset. ASPECTS predicted outcome in a graded fashion (linearly for ASPECTS 6 through 10; pattern ill-defined for ASPECTS 0 through 5) but discriminated individual outcomes weakly. Except perhaps when early ischemic change is extensive, clinicians should not estimate prognosis using ASPECTS alone.

Does clinical-CT 'mismatch' predict early response to treatment with recombinant tissue plasminogen activator?

BACKGROUND

We hypothesized that patients with clinically severe strokes but less severe early ischemic changes on brain CT (i.e., clinical-CT mismatch) may respond better to intravenous recombinant tissue plasminogen activator (i.v. rt-PA) within 3 h of symptom onset.

METHODS

In this secondary analysis of the CLOTBUST data, patients with middle cerebral artery occlusions on transcranial Doppler (TCD) were treated with i.v. rt-PA. Alberta Stroke Program Early CT Scores were obtained with raters blinded to the NIH Stroke Scale and TCD results. Two mismatch criteria and three criteria of response to therapy were explored.

RESULTS

Of 126 patients, 67% had a mismatch type 1 and 74% had a mismatch type 2. The presence of clinical-CT mismatch by either definition did not correlate with any of the three criteria of response to rt-PA. Recanalization was a strong determinant of response, whether or not mismatch was present.

CONCLUSIONS

Mismatch between severity of neurological deficit and CT findings is common but does not predict response to rt-PA therapy given within 3 h.

The ALIAS Pilot Trial

Background and Purpose— In preclinical stroke models, high-dose human albumin confers robust neuroprotection. We investigated the safety and tolerability of this therapy in patients with acute ischemic stroke.

Methods— The ALIAS ( Al bumin i n A cute S troke) Pilot Clinical Trial used a multiple-tier, open-label, dose-escalation design. Subjects with acute ischemic stroke (NIH Stroke Scale [NIHSS] of 6 or above) received a 2-hour infusion of 25% human albumin (ALB) beginning within 16 hours of stroke onset. Six successive ALB dose tiers were assessed ranging from 0.34 to 2.05 g/kg. Neurologic and cardiac function was sequentially monitored. At 3 months, the NIHSS, modified Rankin Scale, and Barthel Index were measured.

Results— Eighty-two subjects (mean age, 65 years) received ALB at 7.8±3.4 hours after stroke onset (mean±standard deviation). Forty-two patients also received standard-of-care intravenous tissue plasminogen activator (tPA). Vital signs were unaltered by ALB treatment. Dose-related increases in plasma albumin and mild hemodilution were maximal at 4 to 12 hours. Age-related plasma brain natriuretic peptide levels increased at 24 hours after ALB but did not predict cardiac adverse events. The sole ALB-related adverse event was mild or moderate pulmonary edema in 13.4% of subjects, which was readily managed with diuretics. In the tPA-treated subgroup, symptomatic intracranial hemorrhage occurred in only one of 42 subjects.

Conclusions— Twenty-five percent human albumin in doses ranging up to 2.05 g/kg was tolerated by patients with acute ischemic stroke without major dose-limiting complications. tPA therapy did not affect the safety profile of ALB. The companion article presents neurologic outcome data and efficacy analysis in these subjects.

Efficacy of thrombolytic (rt-PA) therapy in old stroke patients: the Perugia Stroke Unit experience

The use of intravenous recombinant tissue plasminogen activator (rt-PA) administered within 3 hrs from symptom onset is beneficial in selected patients independent of age; although oldest patients (> or = 80 years) are excluded a priori. We report an experience relative to rt-PA treatment in the oldest patients including outcome at 3 months. Data were from the hospital-based Perugia Stroke Registry. Seventy-two consecutive acute stroke patients, fulfilling NINDS and EUSI-criteria were treated with rt-PA of these 23 patients (30.5%) were > or = 80 years. The median and mean age were, respectively, 72.5 and 71.1 +/- 12.7 years (range 35-94). The proportion of favorable outcome at 3-months did not differ between groups (55% elderly versus 51.1% of younger patients). Proportions of unfavorable outcome and death from baseline were similar in both groups of patients. Age did not influence prognosis in patients treated with rt-PA. The oldest stroke patients should not be excluded from rt-PA treatment on the basis of age per se.

Multimodal use of computed tomography in early acute stroke, part 1

Brain Computed tomography (CT) scan has been used in the past to exclude a hemorrhagic stroke, to determine a possible cause of the stroke patient symptoms, and to demonstrate a stabilized area of hypoperfusional flow. Several results from CT scan studies suggested that we could have new information on prognosis and outcome, localization, and risk of infarction. In this view, CT scan in acute stroke may contribute, using objective measures, to evaluate the inclusion in clinical and therapeutical trials, such as thrombolytic therapy. The lack of consensus among clinicians does not allow a secure and definitive system of CT scan evaluation. Besides its common uses, more recently brain CT scan provides new techniques utilizing advanced algorithms of reconstruction, with promising properties not yet completely verified, to highlight more aspects of acute stroke in the early phase. Despite this limitation, progress on neuroradiological techniques reinforces the concept that brain CT scan remains the key of studies, as well as of validation and routine treatment in terms of feasibility, low cost, and widely availability.

Insular cortical ischaemia does not independently predict acute hypertension or hyperglycaemia within 3 h of onset

OBJECTIVES

To test the hypothesis that insular cortical ischaemia is associated with acute hypertension and hyperglycaemia.

METHODS

From the Canadian Activase for Stroke Effectiveness Study, which included only patients treated with thrombolysis hyperacutely (ie, within 3 h of onset of stroke), 966 patients were identified with ischaemia affecting (n = 685), or sparing (n = 281), the insular cortex. Demographic and clinical data, pretreatment indices of blood pressure, blood glucose, atrial fibrillation, and clinical imaging and outcome measures were compared between the two groups. Multivariable linear regression was used to assess predictors of systolic blood pressure and glucose levels before thrombolysis.

RESULTS

Pretreatment hypertension (p = 0.009), but not hyperglycaemia (p = 0.32), was predicted by insular ischaemia in univariable linear regression analyses. After adjusting for other factors, however, insular cortical ischaemia was not found to be an independent predictor for acute hypertension or hyperglycaemia.

CONCLUSIONS

Raised blood pressure or serum glucose levels in hyperacute (<3 h) cerebral ischaemia is not independently predicted by insular involvement. Several hours are required for sympathetic manifestations of insular ischaemia to evolve.

Thrombolysis in patients older than 80 years with acute ischaemic stroke: Canadian Alteplase for Stroke Effectiveness Study

BACKGROUND

The benefit of intravenous tissue plasminogen activator (tPA) given within 3 h of acute ischaemic stroke to patients over 80 years of age is uncertain.

AIM

To examine the clinical characteristics and complications and the predictors of outcome after intravenous tPA treatment in patients aged > or = 80 years.

METHODS

Data (n = 1135) prospectively collected from the Canadian Alteplase for Stroke Effectiveness Study were reviewed and patients aged > or = 80 years (n = 270) treated with intravenous tPA for acute ischaemic stroke were compared with those aged <80 years (n = 865).

RESULTS

The risk of symptomatic intracerebral haemorrhage did not differ between patients aged > or = 80 years and <80 years (4.4% (95% CI 2.3 to 7.6) v 4.6% (95% CI 3.3 to 6.2), p = 1.0). Favourable outcome, defined as a modified Rankin Score of 0-1 at 90 days, was seen in 26% of patients aged > or = 80 years and in 40% of those <80 (p<0.001). The following baseline characteristics were found to be more common in those aged > or = 80 years than in those aged <80 years: atrial fibrillation (37% v 18%; p<0.001); congestive heart failure (11% v 6%; p = 0.004); hypertension (59% v 48%; p = 0.002); and severity of stroke with a median National Institutes of Health Stroke Scale (NIHSS) score of 16 v 14 (p = 0.004). In the multivariable logistic regression analysis, age > or = 80 years, stroke severity, baseline Alberta Stroke Program Early CT Score and glucose level were found to be the major independent predictors of outcome.

CONCLUSION

In carefully selected elderly patients, the use of intravenous tPA was not found to be associated with an increased risk of symptomatic intracerebral haemorrhage. Age-related differences were seen in the clinical characteristics and outcome in the elderly population.

Alteplase at 0.6 mg/kg for Acute Ischemic Stroke Within 3 Hours of Onset

BACKGROUND AND PURPOSE

Based on previous studies comparing different recombinant tissue plasminogen activator (rt-PA) doses, we performed a clinical trial with 0.6 mg/kg, which is lower than the internationally approved dosage of 0.9 mg/kg, aiming to assess the efficacy and safety of alteplase in acute ischemic stroke for the Japanese.

METHODS

Our prospective, multicenter, single-arm, open-label trial was designed with a target sample size of 100 patients. The primary end points were the proportion of patients with a modified Rankin Scale (mRS) score of 0 to 1 at 3 months and the incidence of symptomatic intracranial hemorrhage (sICH) within 36 hours. Thresholds for these end points were determined by calculating 90% CIs of weighted averages derived from published reports. The protocol was defined according to the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA stroke study with slight modifications.

RESULTS

Among the 103 patients enrolled, 38 had an mRS of 0 to 1 at 3 months; this proportion (36.9%) exceeded the predetermined threshold of 33.9%. sICH within 36 hours occurred in 6 patients; this incidence (5.8%) was lower than the threshold of 9.6%.

CONCLUSIONS

In patients receiving 0.6 mg/kg alteplase, the outcome and the incidence of sICH were comparable to published data for 0.9 mg/kg. These findings indicate that alteplase, when administered at 0.6 mg/kg to Japanese patients, might offer a clinical efficacy and safety that are compatible with data reported in North America and the European Union for a 0.9 mg/kg dose.

Stroke Imaging at 3.0 T

Stroke is a devastating disease with a complex pathophysiology. It is a major cause of death and disability in North America. To fully characterize its extent and effects, one requires numerous specialized anatomical and functional MR techniques, specifically diffusion-weighted imaging, MR angiography, and perfusion-weighted imaging. The advent of 3.0 T clinical scanners has the potential to provide higher quality information in potentially less time compared with 1.5 T stroke-specific MR imaging protocols. This article gives a brief overview of stroke, presents the principles and clinical applications of the relevant MR techniques required for diagnostic stroke imaging at high field, and discusses the advantages, challenges, and limitations of 3.0 T imaging as they relate to stroke.

Predictors of good prognosis in total anterior circulation infarction within 6 h after onset under conventional therapy

OBJECTIVE

We investigated the predictors of good prognosis in total anterior circulation infarction (TACI), under conventional therapy.

METHODS

We enrolled 166 patients with first-ever ischemic stroke within 6 h after onset with symptoms of TACI. Sixty-three patients (38.0%) with good outcome [G group, the modified Rankin Disability Scale (mRS) after 3 months < or =3] and 103 patients (62.0%) with bad outcome (B group, mRS >3) were compared.

RESULTS

On univariate analysis, G group patients were significantly younger, had lower score in the National Institutes of Health Stroke Scale (NIHSS) of total and consciousness sub-score, had lower rate of clinical deterioration. On cranial CT at entry, three early CT signs [hyperdense middle cerebral artery (MCA) sign, hypodensity of >1/3 MCA and brain swelling] were significantly more frequent in the B group. On the second CT at 24-48 h, infarct area as assessed by the Alberta Stroke Programme Early CT Score (ASPECTS) was significantly smaller in the G group. Multivariate analysis with logistic regression revealed age <7 0 years, NIHSS < or =15, no clinical deterioration, and only no brain swelling in early CT signs, and ASPECTS > or =7 as independent predictors of good prognosis.

CONCLUSIONS

Some clinical variables are useful in predicting outcome in TACI within the early period after stroke onset.

Early CT signs in patients with acute middle cerebral artery occlusion: incidence of contrast staining and haemorrhagic transformations after intra-arterial reperfusion therapy

AIM

To investigate how often early computed tomography (CT) signs are associated with blood-brain barrier (BBB) disruption and result in haemorrhagic transformations.

MATERIALS AND METHODS

Serial CT findings were prospectively evaluated in 61 patients with acute middle cerebral artery (MCA) occlusion who underwent initial CT examination within 3h of stroke onset and who were treated with intra-arterial reperfusion therapy within 6h of stroke onset. Obscuration of the margin of the lentiform nucleus and loss of the insular ribbon were evaluated as early CT signs in the deep MCA territories. Cortical effacement was also evaluated. BBB disruption was defined as contrast medium staining in post-therapeutic CT just after reperfusion therapy. The relationship between pre-therapeutic early CT signs and post-therapeutic contrast staining or haemorrhagic transformations was investigated.

RESULTS

The frequency of early CT signs in the deep MCA territories was significantly higher than that of cortical effacement (68.9 versus 27.9%). There were significant correlations between pre-therapeutic early CT signs and post-therapeutic contrast staining in both the deep and superficial MCA territories. Compared with early CT signs in the deep MCA territories, cortical effacement had a significantly higher incidence of post-therapeutic contrast staining (54.8 versus 82.4%). Although not statistically significant, cortical effacement tended to develop into haemorrhagic transformations. There was no correlation between early CT signs in the deep MCA territories and haemorrhagic transformations.

CONCLUSION

Cortical effacement may be an advanced CT sign with BBB disruption and potential risk for haemorrhagic transformations. The presence of early CT signs in the deep MCA territories may not be a contraindication of reperfusion therapy.

Extent of Early Ischemic Changes on Computed Tomography (CT) Before Thrombolysis

BACKGROUND AND PURPOSE

The significance of early ischemic changes (EICs) on computed tomography (CT) to triage patients for thrombolysis has been controversial. The Alberta Stroke Program Early CT Score (ASPECTS) semiquantitatively assesses EICs within the middle cerebral artery territory using a10-point grading system. We hypothesized that dichotomized ASPECTS predicts response to intravenous thrombolysis and incidence of secondary hemorrhage within 6 hours of stroke onset.

METHODS

Data from the European-Australian Acute Stroke Study (ECASS) II study were used in which 800 patients were randomized to recombinant tissue plasminogen activator (rt-PA) or placebo within 6 hours of symptom onset. We retrospectively assessed all baseline CT scans, dichotomized ASPECTS at < or =7 and >7, defined favorable outcome as modified Rankin Scale score 0 to 2 after 90 days, and secondary hemorrhage as parenchymal hematoma 1 (PH1) or PH2. We performed a multivariable logistic regression analysis and assessed for an interaction between rt-PA treatment and baseline ASPECTS score.

RESULTS

We scored ASPECTS >7 in 557 and < or =7 in 231 patients. There was no treatment-by-ASPECTS interaction with dichotomized ASPECTS (P=0.3). This also applied for the 0- to 3-hour and 3- to 6-hour cohorts. However, a treatment-by-ASPECTS effect modification was seen in predicting PH (0.043 for the interaction term), indicating a much higher likelihood of thrombolytic-related parenchymal hemorrhage in those with ASPECTS < or =7.

CONCLUSIONS

In ECASS II, the effect of rt-PA on functional outcome is not influenced by baseline ASPECTS. Patients with low ASPECTS have a substantially increased risk of thrombolytic-related PH.

Imaging of the brain and cerebral vasculature in patients with suspected stroke: advantages and disadvantages of CT and MRI

Although neuroimaging remains the foundation for the diagnosis of cerebrovascular disease, ongoing technologic advances have now opened up new frontiers for stroke evaluation and treatment. Neuroimaging studies can provide crucial information regarding tissue injury (size, location, and degree of reversibility of ischemic injury as well as presence of hemorrhage), vessel status (site and severity of stenoses and occlusions), and cerebral perfusion (size, location, and severity of hypoperfusion). This information can be combined to identify patients with salvageable penumbral tissue who may benefit most from acute therapies. The multimodal combinations of advanced imaging techniques, particularly in the realm of CT and MRI, have emerged as the most promising noninvasive approaches to acute stroke evaluation.

Noncontrast CT in acute stroke

Noncontrast head CT has an important role in the work-up of acute stroke by excluding intracranial hemorrhage and by directly visualizing the parenchymal changes of early infarct. However, noncontrast CT has limited sensitivity and moderate interobserver variability in detecting early infarcts. This article reviews the noncontrast CT appearance and clinical significance of parenchymal changes in early infarct and discusses techniques to optimize their detection.

Xenon CT cerebral blood flow in acute stroke

Acute stroke therapy is evolving rapidly as research moves toward extending the time window for treatment so that more patients can benefit. As physiology-based imaging increasingly is used in patient selection, it is becoming evident that rigid time windows are not applicable to individual patients. Xenon CT has an important role in acute stroke therapeutic intervention as a quantitative, reproducible, rapid, and safe modality, which can provide valuable physiologic data that can optimize patient triage and aid in management.

CT perfusion in acute stroke

As new treatments are developed for stroke, the potential clinical applications of CT perfusion (CTP) imaging in the diagnosis, triage, and therapeutic monitoring of these diseases are certain to increase. Technical advances in scanner hardware and software should no doubt continue to increase the speed, coverage, and resolution of CTP imaging. CTP offers the promise of efficient use of imaging resources and, potentially, of decreased morbidity. Most importantly, current CT technology already permits the incorporation of CTP as part of an all-in-one acute stroke examination to answer the four fundamental questions of stroke triage quickly and accurately, further increasing the contribution of imaging to the diagnosis and treatment of acute stroke.

Perfusion computed tomography: prediction of final infarct extent and stroke outcome

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) has not been previously applied to perfusion CT (CTP). Five raters assigned ASPECTS to baseline noncontrast CT (NCCT), CT angiography source images (CTA-SI), CTP source images (CTP-SI), and CTP maps of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) from 37 consecutive patients with less than 6-hour anterior circulation ischemic stroke. Major reperfusion was identified on follow-up imaging. Mean baseline ASPECTS was compared with follow-up imaging ASPECTS. Rates of favorable outcome were compared for dichotomized baseline ASPECTS. In patients with major reperfusion, mean CBV and CTP-SI ASPECTS closely predicted final infarct ASPECTS. In patients without major reperfusion, mean CBF and MTT ASPECTS best predicted final infarct ASPECTS. There were significant increases in rates of favorable outcome for CTP-SI and CBV ASPECTS of greater than 6, versus less than or equal to 6, but not for other baseline CT modalities. ASPECTS applied to CTP is more accurate at identifying the extent of reversible and irreversible ischemia and at predicting final clinical outcome than NCCTor CTA-SI.

Role of CT Angiography in Thrombolysis Decision-Making for Patients With Presumed Seizure at Stroke Onset

BACKGROUND AND PURPOSE

The presence of seizure at stroke onset is a contraindication for intravenous tissue plasminogen activator treatment. A significant proportion of these patients' deficits are not attributable to Todd's paralysis and could be attributable to reversible ischemia. Currently there are no established methods of differentiating Todd's paralysis from ischemic stroke/early seizure. We sought to determine whether computed tomographic angiography (CTA) can be helpful in differentiating the 2.

METHODS

Three hundred and twenty six patients underwent noncontrast CT and CTA for acute stroke at our institution over 3 years (June 2002 to April 2005). Of them, 116 had disabling deficits and presented within 3 hours. We reviewed the clinical data, noncontrast CT, CTA, electroencephalogram and outcome of these patients and identified those who presented with presumed seizure activity at stroke onset (seizure or altered consciousness at stroke onset).

RESULTS

Nine (7.7%) patients had a concern of seizure at stroke onset. Median age 73 years (range, 31 to 85 years), median National Institutes of Health Stroke Scale (NIHSS) score 12 (range, 5 to 29). CTA showed proximal middle cerebral artery occlusion in 2 and distal middle cerebral artery occlusion in 3 patients. All 5 of these patients had evidence of infarction on follow-up (stroke+early seizure group-intracranial occlusion present). Three of these patients received intravenous tissue plasminogen activator because they were deemed to have "ischemic tissue at risk". Four patients had normal CT and CTA studies and recovered completely in 24 hours (Todd's paralysis only group-intracranial occlusion negative).

CONCLUSIONS

Seizure at stroke onset was relatively uncommon in a consecutive cohort of acute stroke patients. CTA was a useful modality in differentiating Todd's paralysis from early seizure and ischemia by detection of intracranial occlusion and may contribute to decision-making for thrombolysis.

The ASPECTS template is weighted in favor of the striatocapsular region

The extent of cerebral infarction correlates with increased risk of intracerebral hemorrhage (ICH) following recombinant tissue plasminogen activator (rt-PA) administration. The Alberta Stroke Program Early CT Score (ASPECTS) is a widely used, validated method which assesses involvement of 10 selected regions of the MCA territory. An ASPECTS score >7 is associated with a higher risk of ICH following thrombolysis than lower scores. To understand the internal structure of the ASPECTS template better, we estimated the infarct volume corresponding to each region. We hypothesized that, in the ASPECTS scoring system, the striatocapsular region is weighted disproportionally. Four experienced radiologists rated individual ASPECTS regions on subacute CT images (day 5-day 10) of 19 patients with MCA territory stroke. Infarct volume was determined from manual segmentation of infarcts on CT images. Linear regression was used to estimate the regional volume associated with each ASPECTS region. The ASPECTS regions are weighted unequally with the striatocapsular region accounting for 21% of the MCA territory infarct volume. Together, the 10 ASPECTS regions account for approximately 51% of the maximum MCA infarct territory volume. These findings should provide impetus for research to develop a scoring system explicitly based on regional hemorrhage risk as an aid to selecting patients for thrombolysis.

Early ischemic edema on cerebral computed tomography: its relation to diffusion changes and hypoperfusion within 6 h after human ischemic stroke. A comparison of CT, MRI and PET

BACKGROUND

Brain tissue hypoattenuation on early computed tomography is frequently included in decision making in acute stroke management. However, its pathophysiological counterpart needs further evaluation.

METHODS

By comparative imaging with diffusion-weighted imaging and 15O-water positron emission tomography we aimed to interpret early (<6 h) hypoattenuation.

RESULTS

In 11 patients, the hypoattenuation corresponded to a decreased proton diffusion (median 115.9% relative DWI value) measured by magnetic resonance imaging and to a severe hypoperfusion (below 12 ml/100 g/ min) assessed by positron emission tomography. The volume of parenchymal hypoattenuation correlated to the tissue with disturbed diffusion (Spearman's rho=0.73), but largely underestimated the hypoperfusion below 20 ml/100 g/min.

CONCLUSIONS

Early hypoattenuation reflects the coupling of the severity of ischemia and resulting diffusion changes. It allows an estimate of the infarct core but underestimates the penumbral hypoperfusion.

Flow Diversion in Transcranial Doppler Ultrasound Is Associated with Better Improvement in Patients with Acute Middle Cerebral Artery Occlusion

BACKGROUND

Flow diversion (FD) can occur with an acute middle cerebral artery (MCA) occlusion. FD is thought to represent the collateral blood flow to the occluded MCA territory, but it is unclear whether or not FD lessens the stroke severity or leads to improved outcome.

METHODS

Patients with a proximal MCA occlusion were selected from the CLOTBUST trial data bank. FD to the anterior or posterior cerebral artery was determined using transcranial Doppler ultrasound. Stroke severity and clinical improvement were measured using the National Institutes of Health Stroke Scale (NIHSS) scores.

RESULTS

We evaluated 47 patients with an isolated M1 MCA occlusion who received intravenous tissue-type plasminogen activator (t-PA) within 3 h of symptom onset. FD was present in 83% of the patients. Median baseline NIHSS scores were 15.5 in the FD- group and 18 in the FD+ group (n.s.). Complete recanalization rates were 25 and 25.6% (n.s.). In 35 patients with a persistent occlusion, the average NIHSS score reduction was 22% (FD+) and 0.52% (FD-) during 90 min after t-PA bolus (p=0.017), and 29 versus -25% during the first 24 h after the t-PA bolus, respectively (p=0.01).

CONCLUSIONS

In patients with persistent MCA occlusions after thrombolytic treatment, arterial blood flow diversion is associated with earlier and better neurological improvement. FD has protective effects on the ischemic brain tissue with persistent MCA occlusion.

Selecting Patients for Early Stroke Treatment with Penumbra Images

Review of results of experimental and clinical studies indicates that the area of physiologically impaired, but potentially salvageable, tissue surrounding the central core of focal cerebral ischemia that develops shortly after onset of vessel occlusion is complex and dynamic with severity and duration thresholds for hypoxic stress and injury that are specific to tissue site, cell type, molecular pathway or gene expression investigated, and efficiency of collateral or residual flow and reperfusion. Identification of this ischemic penumbra in the acute stroke clinical setting is an important goal for stroke researchers and clinicians. Recent advances in neuroimaging allowed a better understanding of this physiopathological process. However, there is not a perfect penumbra imaging technique and each one has its own advantages and disadvantages. Numerous thrombolytic and potentially neuroprotective agents have been studied in stroke patients, with little success, as the only approved therapy is thrombolysis with recombinant tissue plasminogen activator within 3 h of stroke onset in highly selected patients (<10% of all acute stroke patients in some specialized centers). One major obstacle in the development of effective therapies for ischemic stroke has been the lack of versatile imaging techniques. The development of penumbra concept and its detection through modern cerebral image techniques can extend the patients' selection for thrombolysis. A number of multicenter clinical trials are now under way to test these models and confirm the utility of penumbra imaging for treatment decisions. Present knowledge about visualization of the salvageable penumbra suggests a promising future in which penumbra imaging studies are performed routinely in the acute stroke setting and the data provided by these studies assist in individualizing therapeutic decisions and identifying effective therapies that can be delivered at late time points. So, the main target of management is 'penumbra', or salvageable tissue, which is primarily dependent upon the expediency of the whole process, better expressed by the phrase 'Penumbra (and not Time) is Brain'.

Thrombolysis in acute ischemic stroke: successes, failures, and new hopes

Evidence from randomized clinical trials indicates that systemic administration of recombinant tissue plasminogen activator (rtPA) is a highly effective treatment for acute ischemic stroke, provided that treatment is administered within the first 3 h after stroke onset. An absolute increase in favorable outcome of up to 13% has been reported, and a pooled analysis of six randomized trials has shown that, although the sooner rtPA is given the greater the benefit, efficacy is present up to 4.5 h after stroke onset. Despite of the spreading use of tPA in different countries and continents, there are still a number of burdens and failures in the optimal accomplishment of thrombolytic treatment. rtPA is used in less than 4% of patients, reperfusion and complete recovery is achieved in less than 50% of patients, and treatment is denied to many patients. However, important advances in clinical investigation suggest that new aims and hopes will be achieved in the near future. Ultrasound-enhanced systemic thrombolysis, the use of MRI for selecting acute stroke patients for IV or IA thrombolysis after 3 h, mechanical embolus disruption or removal in proximal artery occlusions, and the potential usefulness of new biomarkers of blood brain barrier disruption and hemorrhagic risk are promising strategies that may improve the risk/benefit ratio and increase the number of patients who will benefit from thrombolytic therapy.

Presence of Early Ischemic Changes on Computed Tomography Depends on Severity and the Duration of Hypoperfusion

Background and Purpose— To evaluate the clinical significance of early ischemic change (EIC) on computed tomography (CT), pertinent factors that contribute to the appearance of EIC.

Methods— Both CT and technetium-99m hexamethylpropylene amine oxime were performed on a total of 53 patients (34 men, 19 women, mean 69.7 years old) with acute embolic stroke within 6 hours of onset. Patients were excluded if they showed definite clinical recovery or were administered thrombolytic agents. EIC was evaluated using Alberta Stroke Program Early CT Score (ASPECTS). Residual cerebral blood flow (CBF) was determined on SPECT. Variables that were considered pertinent were patients’ age, gender, neurological severity, symptom duration, and residual CBF. Using significant pertinent factors for EIC, separate analyses of brain swelling without hypoattenuation and parenchymal hypoattenuation were performed.

Results— Patients with EIC (n=37) showed severe neurological deficits, a longer duration and severe hypoperfusion. A positive correlation was observed between ASPECTS and residual CBF ( P =0.002; Kruskal-Wallis test). A logistic-regression analysis revealed that both symptom duration ( r =0.024, P =0.006) and severity of hypoperfusion ( r = −12.167, P =0.006) are independent factors related to EIC. Symptom duration and residual CBF were significantly different among patients with parenchymal hypoattenuation (n=32), brain swelling without hypoattenuation (n=5), and no EIC ( P =0.018 and P =0.001, respectively; one-way ANOVA).

Conclusions— The presence of EIC is determined by the duration and the degree of hypoperfusion. This finding supports the hypothesis that tissue damage may be evaluated by a combination of onset time and the presence of EIC.

Imaging of the brain in acute ischaemic stroke: comparison of computed tomography and magnetic resonance diffusion-weighted imaging

BACKGROUND AND OBJECTIVES

Controversy exists about the optimal imaging technique in acute stroke. It was hypothesised that CT is comparable with DWI, when both are read systematically using quantitative scoring.

METHODS

Ischaemic stroke patients who had CT within six hours and DWI within seven hours of onset were included. Five readers used a quantitative scoring system (ASPECTS) to read the baseline (b) and follow up CT and DWI. Use of MRI in acute stroke was also assessed in patients treated with tissue plasminogen activator (tPA) by prospectively recording reasons for exclusion. Patients were followed clinically at three months.

RESULTS

bDWI and bCT were available for 100 consecutive patients (admission median NIHSS = 9). The mean bDWI and bCT ASPECTS were positively related (p<0.001). The level of interrater agreement ranged from good to excellent across all modalities and time periods. Bland-Altman plots showed more variability between bCT and bDWI than at 24 hours. The difference between bCT and bDWI was < or =2 ASPECTS points. Of bCT scans with ASPECTS 8-10, 81% had DWI ASPECTS 8-10. Patients with bCT ASPECTS of 8-10 were 1.9 times more likely to have a favourable outcome at 90 days than those with a score of 0-7 (95% CI 1.1 to 3.1, p = 0.002). The relative likelihood of favourable outcome with a bDWI ASPECTS 8-10 was 1.4 (95% CI 1.0 to 1.9, p = 0.10). Of patients receiving tPA 45% had contraindications to urgent MRI.

CONCLUSION

The differences between CT and DWI in visualising early infarction are small when using ASPECTS. CT is faster and more accessible than MRI, and therefore is the better neuroimaging modality for the treatment of acute stroke.

Emergent stenting of extracranial internal carotid artery occlusion in acute stroke has a high revascularization rate

BACKGROUND AND PURPOSE

Acute ischemic stroke attributable to extracranial internal carotid artery (ICA) occlusion is frequently associated with severe disability or death. In selected cases, revascularization with carotid artery stenting has been reported, but the safety, recanalization rate, and clinical outcomes in consecutive case series are not known.

METHODS

We retrospectively reviewed all of the cases of ICA occlusions that underwent cerebral angiography with the intent to revascularize over a 38-month period. Two groups were identified: (1) patients who presented with an acute clinical presentation within 6 hours of symptom onset (n=15); and (2) patients who presented subacutely with neurologic fluctuations because of the ICA occlusion (n=10).

RESULTS

Twenty-five patients with a mean age of 62+/-11 years and median National Institutes of Health Stroke Scale (NIHSS) of 14 were identified. Twenty-three of the 25 patients (92%) were successfully revascularized with carotid artery stenting. Patients in group 1 were younger and more likely to have a tandem occlusion and higher baseline NIHSS when compared with group 2. Patients in group 2 were more likely to show early clinical improvement defined as a reduction of their NIHSS by > or =4 points and a modified Rankin Score of < or =2 at 30-day follow-up. Two clinically insignificant adverse events were noted: 1 asymptomatic hemorrhage and 1 nonflow-limiting dissection.

CONCLUSIONS

Endovascular treatment of acute ICA occlusion appears to have a high-recanalization rate and be relatively safe in our cohort of patients with acute ICA occlusion. Future prospective studies are necessary to determine which patients are most likely to benefit from this form of therapy.

Importance of Early Ischemic Computed Tomography Changes Using ASPECTS in NINDS rtPA Stroke Study

BACKGROUND AND PURPOSE

The importance of early ischemic change (EIC) on baseline computed tomography (CT) in the decision to thrombolyze the patient with acute ischemic stroke has been controversial. ASPECTS is a semiquantitative scale that scores the extent of EIC within the middle cerebral artery territory. We examined whether ASPECTS could be a treatment modifier by systematically reviewing the CT scans in the NINDS rtPA Stroke Study.

METHODS

Six hundred eight of the 624 CT scans were available and of sufficient quality. One of 2 teams (n=3 each) of expert ASPECTS readers evaluated each scan for an ASPECTS value using a consensus score approach. Each team was blind to all clinical information except symptom side and blind to follow-up imaging and outcome information. ASPECTS values were stratified before analysis. Multivariable logistic regression was used to determine if an ASPECTS by treatment interaction existed on treatment response, outcome, and intracerebral hemorrhage risk.

RESULTS

A total of 57.2% (348 of 608) of scans showed EIC with an ASPECTS <10. ASPECTS dichotomized into 8 to 10 and <8 did not have a treatment-modifying effect on good outcome but showed a trend to lower mortality at 90 days with tPA (relative risk 0.67, 95% confidence interval 0.41 to 1.06, P=0.10). ASPECTS 8 to 10 were associated with a trend to larger benefit of tPA with a number needed to treat (NNT) of 5 versus ASPECTS 3 to 7 with a NNT of 8.

CONCLUSIONS

There was no evidence of treatment effect modification by the baseline ASPECTS value in the NINDS rtPA Stroke Study. Therefore, exclusion of patients for thrombolysis within 3 hours of symptom onset based on EIC is not supported by our data. There is a trend to reduced mortality and increased benefit to rtPA if the baseline CT scan is favorable (ASPECTS >7).

Intravenous Tirofiban With Intra-Arterial Urokinase and Mechanical Thrombolysis in Stroke

BACKGROUND AND PURPOSE

To evaluate preliminarily efficacy and safety of intravenous tirofiban combined with mechanical clot disruption and urokinase in patients with stroke attributable to major cerebral artery occlusion.

METHODS

Eleven consecutive patients with stroke attributable to acute occlusion of a major cerebral artery were treated with an intravenous bolus injection of the platelet glycoprotein IIb/IIIa antagonist tirofiban combined with heparin and by endovascular procedures including mechanical thrombolysis and locally delivered urokinase. Of the 11 cases, 9 involved angioplasty and 2 only microcatheter and microguidewire manipulation.

RESULTS

There were 7 patients with internal carotid or middle cerebral artery occlusion treated within 6 hours and 4 patients with basilar artery occlusion treated within 12 hours of symptom onset. Median National Institutes of Health Stroke Scale (NIHSS) score on admission was 20. After the interventional procedure, vessel recanalization was partial (thrombolysis in myocardial infarction grade flow 2 [TIMI 2]) in 7 patients and absent or insufficient in 4 patients. Twenty-four hours after the procedure, all the patients but 1 improved substantially, and on control angiography, the occluded vessel was totally patent (TIMI 3) in 10 of the 11 patients. One patient with partial recanalization did not improve and died 3 months later from pulmonary embolism. Neither a symptomatic intracerebral hemorrhage nor systemic bleedings requiring blood transfusion occurred in any patient. At discharge, median NIHSS score was 2. The 3-month outcome was excellent in 8 patients (modified Rankin Scale [mRS] 0 to 1), good in 2 patients (mRS 2), and poor in 1 patient (mRS 6).

CONCLUSIONS

The combination of intravenous tirofiban with intra-arterial mechanical clot disruption and urokinase may be successful in reopening an occluded major cerebral vessel without increasing the hemorrhagic risk and with good functional outcome. This strategy cannot be recommended as the systematic treatment of stroke attributable to major cerebral artery occlusion until tested in a controlled study design.

Neuroimaging of ischemia and infarction

Since the introduction of thrombolytic therapy as the foundation of acute stroke treatment, neuroimaging has rapidly advanced to empower therapeutic decision making. Diffusion-weighted imaging is the most sensitive and accurate method for stroke detection, and, allied with perfusion-weighted imaging, provides information on the functional status of the ischemic brain. It can also help to identify a response to thrombolytic and neuroprotective therapies. Additionally, multimodal magnetic resonance imaging, including magnetic resonance angiography, offers information on stroke mechanism and pathophysiology that can guide long-term medical management. Multimodal computed tomography is a comprehensive, cost-effective, and safe stroke imaging modality that can be easily implemented in the emergency ward and that offers fast and reliable information with respect to the arterial and functional status of the ischemic brain. Accessibility, contraindications, cost, speed, and individual patient-determined features influence which is the best imaging modality to guide acute stroke management.

“Clinical-CT Mismatch” and the Response to Systemic Thrombolytic Therapy in Acute Ischemic Stroke

Background and Purpose— Mismatch between clinical deficits and imaging lesions in acute stroke has been proposed as a method of identifying patients who have hypoperfused but still have viable brain, and may be especially apt to respond to reperfusion therapy. We explored this hypothesis using a combined database including 4 major clinical trials of intravenous (IV) thrombolytic therapy.

Methods— To determine what the radiological correlates of a “matched” functional deficit are, we calculated the relationship between the ASPECT score of the 24-hour (follow-up) CT scan and the 24-hour National Institutes of Health Stroke Scale (NIHSS) score on the subsample with ASPECT scores performed at this time (n=820). Based on this empirical relationship, we computed the absolute difference between the observed baseline ASPECT score and the “expected” score (ie, matched) based on baseline NIHSS for all patients (n=2131). We tested whether patients with better than expected baseline ASPECTS were more likely to benefit from IV recombinant tissue plasminogen activation (rtPA).

Results— At 24 hours, there was a strong, linear, negative correlation between NIHSS and ASPECTS (r 2 =0.33, P <0.0001); on average, an increase of 10 points on NIHSS corresponded to a decrease of ≈3 points on ASPECTS. At baseline, the average degree of mismatch between the observed and “expected” ASPECTS was 2.1 points (interquartile range, 1.0 to 3.4). However, multiple analyses failed to reveal a consistent relationship between the degree of clinical-CT mismatch at baseline and a patient’s likelihood of benefiting from IV rtPA.

Conclusion— Clinical-CT mismatch using ASPECT scoring does not reliably identify patients more or less likely to benefit from IV rtPA.

Multidetector computed tomography of the head in acute stroke: predictive value of different patterns of the dense artery sign revealed by maximum intensity projection reformations for location and extent of the infarcted area

Maximum intensity projections reconstructions from 2.5 mm unenhanced multidetector computed tomography axial slices were obtained from 49 patients within the first 6 h of anterior-circulation cerebral strokes to identify different patterns of the dense artery sign and their prognostic implications for location and extent of the infarcted areas. The dense artery sign was found in 67.3% of cases. Increased density of the whole M1 segment with extension to M2 of the middle cerebral artery was associated with a wider extension of cerebral infarcts in comparison to M1 segment alone or distal M1 and M2. A dense sylvian branch of the middle cerebral artery pattern was associated with a more restricted extension of infarct territory. We found 62.5% of patients without a demonstrable dense artery to have a limited peripheral cortical or capsulonuclear lesion. In patients with a 7-10 points on the Alberta Stroke Early Programme Computed Tomography Score and a dense proximal MCA in the first hours of ictus the mean decrease in the score between baseline and follow-up was 5.09+/-1.92 points. In conclusion, maximum intensity projections from thin-slice images can be quickly obtained from standard computed tomography datasets using a multidetector scanner and are useful in identifying and correctly localizing the dense artery sign, with prognostic implications for the entity of cerebral damage.

Ion channels involved in stroke

Ion channels are membrane proteins that flicker open and shut to regulate the flow of ions down their electrochemical gradient across the membrane and consequently regulate cellular excitability. Every living cell expresses ion channels, as they are critical life-sustaining proteins. Ion channels are generally either activated by voltage or by ligand interaction. For each group of ion channels the channels' molecular biology and biophysics will be introduced and the pharmacology of that group of channels will be reviewed. The in vitro and in vivo literature will be reviewed and, for ion channel groups in which clinical trials have been conducted, the efficacy and therapeutic potential of the neuroprotective compounds will be reviewed. A large part of this article will deal with glutamate receptors, focusing specifically on N-methyl-D-aspartate (NMDA) receptors. Although the outcome of clinical trials for NMDA receptor antagonists as therapeutics for acute stroke is disappointing, the culmination of these failed trials was preceded by a decade of efforts to develop these agents. Sodium and calcium channel antagonists will be reviewed and the newly emerging efforts to develop therapeutics targeting potassium channels will be discussed. The future development of stroke therapeutics targeting ion channels will be discussed in the context of the failures of the last decade in hopes that this decade will yield successful stroke therapeutics.

Thrombolysis for acute ischemic stroke: results of the Canadian Alteplase for Stroke Effectiveness Study

BACKGROUND

Thrombolysis for acute ischemic stroke has remained controversial. The Canadian Alteplase for Stroke Effectiveness Study, a national prospective cohort study, was conducted to assess the effectiveness of alteplase therapy for ischemic stroke in actual practice.

METHODS

The study was mandated by the federal government as a condition of licensure of alteplase for the treatment of stroke in Canada. A registry was established to collect data over 2.5 years for stroke patients receiving such treatment from Feb. 17, 1999, through June 30, 2001. All centres capable of administering thrombolysis therapy according to Canadian guidelines were eligible to submit patient data to the registry. Data collection was prospective, and follow-up was completed at 90 days after stroke. Copies of head CT scans obtained at baseline and at 24-48 hours after the start of treatment were submitted to a central panel for review.

RESULTS

A total of 1135 patients were enrolled at 60 centres in all major hospitals across Canada. The registry collected data for an estimated 84% of all treated ischemic stroke patients in the country. An excellent clinical outcome was observed in 37% of the patients. Symptomatic intracranial hemorrhage occurred in only 4.6% of the patients (95% confidence interval [CI] 3.4%-6.0%); however, 75% of these patients died in hospital. An additional 1.3% (95% CI 0.7%-2.2%) of patients had hemiorolingual angioedema.

CONCLUSIONS

The outcomes of stroke patients undergoing thrombolysis in Canada are commensurate with the results of clinical trials. The rate of symptomatic intracranial hemorrhage was low. Stroke thrombolysis is a safe and effective therapy in actual practice.

The Evolving Role of Advanced MR Imaging as a Management Tool for Adult Ischemic Stroke: A Western-European Perspective

New and more advanced diagnostic imaging techniques for acute stroke triage have the potential to not only improve the quality of care but also reduce health care costs. Although sufficiently large and methodologically sound studies with regard to cost effectiveness of MR imaging are lacking, the overall impression is that MR imaging has revolutionized not only the diagnosis but also the open and investigational management of neurologically ill patients.

Early Signs of Brain Infarction at CT: Observer Reliability and Outcome after Thrombolytic Treatment—Systematic Review

PURPOSE

To review systematically all reported early computed tomographic (CT) signs in acute ischemic stroke to determine interobserver agreement and the relationship between early CT signs and patient outcome with or without thrombolysis.

MATERIALS AND METHODS

A systematic review of the literature was conducted by using Cochrane Stroke Group methodology to identify studies published between 1990 and 2003 that were performed to assess interobserver agreement about early signs of infarction on CT scans obtained within 6 hours after onset of stroke symptoms and determine the relation of early signs of infarction to clinical outcome, including any interactive effect of thrombolysis. Interobserver agreement was measured with the kappa statistic, sensitivity, and specificity. The relation of early signs to clinical outcome with or without thrombolysis was assessed with calculated odds ratios and 95% confidence intervals.

RESULTS

In 15 studies of interobserver agreement (median of 30 CT scans and six raters), the prevalence of all early infarction signs was 61% +/- 21 (standard deviation). Interobserver agreement (kappa statistics) ranged from 0.14 to 0.78 for any early infarction sign. The mean sensitivity and specificity for detection of early infarction signs with CT were 66% (range, 20%-87%) and 87% (range, 56%-100%), respectively. Experience improved detection, but knowledge of symptoms did not. In 15 studies of early infarction signs and outcome (including seven thrombolysis trials) in 3468 patients, any early infarction sign increased the risk of poor outcome (odds ratio, 3.11; 95% confidence interval: 2.77, 3.49). Two studies that sought interaction between early infarction signs and thrombolysis found no evidence that thrombolysis given in the presence of early infarction signs resulted in worse outcome than that due to early signs alone.

CONCLUSION

Further work is required to determine which signs are most reliably detected, whether scoring systems help to improve detection, and whether any early infarction sign should influence decisions concerning thrombolysis.

Unenhanced CT and Acute Stroke Physiology

Unenhanced CT remains the most widely used imaging technique and is the standard of care for acute stroke evaluation. Early ischemic signs (EIS) within the first 3 to 6 hours of symptom onset (eg, parenchymal hypodensity, sulcal effacement, and dense vessel) have been advocated as a triage tool for thrombolytic therapy. Recent studies have challenged the relevance of these EIS within 3 hours of stroke onset, with advanced MR and CT methods increasingly competing with unenhanced CT as the primary imaging modality for acute ischemia. Nonetheless, the insights regarding acute stroke physiology provided by studying the CT evolution of early ischemic signs continue to be valuable for the informed interpretation of all stroke images. It is these insights that comprise the topic of this article.

The Evolving Role of Acute Stroke Imaging in Intravenous Thrombolytic Therapy: Patient Selection and Outcomes Assessment

In early trials of thrombolysis, unenhanced CT was used to exclude patients with brain hemorrhage or large infarctions but was insensitive to stroke pathophysiology or early signs of cerebral ischemia or infarction. Currently, CT angiography, CT perfusion, and MR imaging can provide information about stroke mechanisms and prognosis, quantify penumbral tissue, and support risk stratification and patient selection. This article reviews the role of neuroimaging in the original intravenous thrombolytic trials, current application of these technologies, and the potential future role of imaging to extend the time window for thrombolysis and to augment therapeutic success.

Alberta Stroke Program Early CT Score in Acute Stroke Triage

In the setting of acute stroke evaluation, CT is accessible, versatile, available, inexpensive, and, most importantly, fast. Its use extends beyond that of identifying intracranial hemorrhage. We have emphasized the importance of clinical assessment, supported by a systematic approach to unenhanced CT interpretation using the Alberta Stroke Program Early CT Score for determining the extent of early ischemic change. The use of CT bolus techniques (providing vascular CT angiography, CT angiography source images, and quantitative CT perfusion maps) can augment the clinical information obtained from unenhanced CT. CT is likely to remain the workhorse of acute stroke imaging for some time to come.

Sex-based differences in response to recombinant tissue plasminogen activator in acute ischemic stroke: a pooled analysis of randomized clinical trials

BACKGROUND AND PURPOSE

Women experience worse outcomes after stroke compared with men. Prior work has suggested sex-based differences in coagulation and fibrinolysis markers in subjects with acute stroke. We explored whether sex might modify the effect of recombinant tissue plasminogen activator (rtPA) on outcomes in patients with acute ischemic stroke.

METHODS

Using a combined database including subjects from the National Institute of Neurological Disorders and Stroke (NINDS), Alteplase Thrombolysis for Acute Noninterventional Therapy in Ischemic Stroke (ATLANTIS) A and B, and the Second European Cooperative Acute Stroke Study (ECASS II) trials, we examined 90-day outcomes in patients randomized to rtPA versus placebo by sex. We used logistic regression to control for potential confounders.

RESULTS

Among 988 women treated between 0 and 6 hours from symptom onset, patients receiving rtPA were significantly more likely than those receiving placebo to have a modified Rankin Score < or =1 (40.5% versus 30.3%, P<0.0008). Among 1190 men, the trend toward benefit in the overall group did not reach statistical significance (38.5% versus 36.7%, P=0.52). An unadjusted analysis showed that women were significantly more likely to benefit from rtPA compared with men (P=0.04). Controlling for age, baseline National Institutes of Health Stroke Scale, diabetes, symptom onset to treatment time, prior stroke, systolic blood pressure, extent of hypoattenuation on baseline computed tomography scan and several significant interaction terms (including onset to treatment time-by-treatment and systolic blood pressure-by treatment) did not substantially change the strength of the interaction between gender and rtPA treatment (P=0.04).

CONCLUSIONS

In this pooled analysis of rtPA in acute ischemic stroke, women benefited more than men, and the usual gender difference in outcome favoring men was not observed in the thrombolytic therapy group. For patients presenting at later time intervals, when the risks and benefits of rtPA are more finely balanced, sex may be an important variable to consider for patient selection.