Risk for symptomatic intracerebral hemorrhage after thrombolysis assessed by diffusion-weighted magnetic resonance imaging

Influence of cognitive impairment on the management of ischaemic stroke

BACKGROUND

Because of ageing of the population, it is more and more frequent to treat ischaemic stroke patients with pre-stroke cognitive impairment (PSCI). Currently, there is no specific recommendation on ischaemic stroke management in these patients, both at the acute stage and in secondary prevention. However, these patients are less likely to receive treatments proven effective in randomised controlled trials, even in the absence of contra-indication.

OBJECTIVE

To review the literature to assess efficacy and safety of validated therapies for acute ischaemic stroke and secondary prevention in PSCI patients.

RESULTS

Most randomised trials did not take into account the pre-stroke cognitive status. The few observational studies conducted at the acute stage or in secondary prevention, did not provide any information that the benefit could be either lost or replaced by harm in the presence of PSCI.

CONCLUSIONS

There is no reason not to treat ischaemic stroke patients with PSCI according to the currently available recommendations for acute management and secondary prevention. Further observational studies are needed and pre-stroke cognition should be taken into account in future stroke trials.

Oxfordshire Community Stroke Project classification improves prediction of post-thrombolysis symptomatic intracerebral hemorrhage

Background

The Oxfordshire Community Stroke Project (OCSP) classification is a simple stroke classification system with value in predicting clinical outcomes. We investigated whether and how the addition of OCSP classification to the Safe Implementation of Thrombolysis in Stroke (SITS) symptomatic intracerebral hemorrhage (SICH) risk score improved the predictive performance.

Methods

We constructed an extended risk score by adding an OCSP component, which assigns 3 points for total anterior circulation infarcts, 0 point for partial anterior circulation infarcts or lacunar infarcts. Patients with posterior circulation infarcts were assigned an extended risk score of zero. We analyzed prospectively collected data from 4 hospitals to compare the predictive performance between the original and the extended scores, using area under the receiver operating characteristic curve (AUC) and net reclassification improvement (NRI).

Results

In a total of 548 patients, the rates of SICH were 7.3% per the National Institute of Neurological Diseases and Stroke (NINDS) definition, 5.3% per the European-Australasian Cooperative Acute Stroke Study (ECASS) II, and 3.5% per the SITS-Monitoring Study (SITS-MOST). Both scores effectively predicted SICH across all three definitions. The extended score had a higher AUC for SICH per NINDS (0.704 versus 0.624, P = 0.015) and per ECASS II (0.703 versus 0.612, P = 0.016) compared with the SITS SICH risk score. NRI for the extended risk score was 22.3% (P = 0.011) for SICH per NINDS, 21.2% (P = 0.018) per ECASS II, and 24.5% (P = 0.024) per SITS-MOST.

Conclusions

Incorporation of the OCSP classification into the SITS SICH risk score improves risk prediction for post-thrombolysis SICH.

Leukoaraiosis predicts cortical infarct volume after distal middle cerebral artery occlusion

BACKGROUND AND PURPOSE

Leukoaraiosis (LA) predominantly affects the subcortical white matter, but mounting evidence suggests an association with cortical microvascular dysfunction and potentially decreased cortical ischemic tolerance. Thus, we sought to assess whether preexisting LA is predictive of the cortical infarct volume after middle cerebral artery branch occlusion and whether it relates to a worse outcome.

METHODS

We analyzed data from 117 consecutive patients with middle cerebral artery branch occlusion as documented by admission computed tomography angiography. Baseline clinical, laboratory, and outcome data, as well as final cortical infarct volumes, were retrospectively analyzed from a prospectively collected database. LA severity was assessed on admission computed tomography using the van Swieten scale grading the supratentorial white matter hypoattenuation. Infarct volume predicting a favorable 90-day outcome (modified Rankin Scale score≤2) was determined by receiver operating characteristic curves. Multivariable linear and logistic regression analyses were used to identify independent predictors of the final infarct volume and outcome.

RESULTS

Receiver operating characteristic curve analyses indicated that a final infarct volume of ≤27 mL best predicted a favorable 90-day outcome. Severe LA (odds ratio, 11.231; 95% confidence interval, 2.526-49.926; P=0.001) was independently associated with infarct volume>27 mL. Severe LA (odds ratio, 3.074; 95% confidence interval, 1.055-8.961; P=0.040) and infarct volume>27 mL (odds ratio, 9.156; 95% confidence interval, 3.191-26.270; P<0.001) were independent predictors of a poor 90-day outcome (modified Rankin Scale, 3-6).

CONCLUSIONS

The presence of severe, subcortical LA contributes to larger cortical infarct volumes and worse functional outcomes adding to the notion that the brain is negatively affected beyond LA's macroscopic boundaries.

The role of advanced neuroimaging in intracerebral hemorrhage

In this report, the authors sought to summarize existing literature to provide an overview of the currently available techniques and to critically assess the evidence for or against their application in intracerebral hemorrhage (ICH) for management, prognostication, and research. Functional imaging in ICH represents a potential major step forward in the ability of physicians to assess patients suffering from this devastating illness due to the advantages over standing imaging modalities focused on general tissue structure alone, but its use is highly controversial due to the relative paucity of literature and the lack of consolidation of the predominantly small data sets that are currently in existence. Current data support that diffusion tensor imaging and tractography, diffusion-perfusion weighted MRI techniques, and functional MRI all possess major potential in the areas of highlighting motor deficits, motor recovery, and network reorganization. Novel clinical studies designed to objectively assess the value of each of these modalities on a wider scale in conjunction with other methods of investigation and management will allow for their rapid incorporation into standard practice.

Dose-related effects of statins on symptomatic intracerebral hemorrhage and outcome after thrombolysis for ischemic stroke

BACKGROUND AND PURPOSE

The aim of our study was to assess whether statins have dose-dependent effects on risk of symptomatic intracerebral hemorrhage (sICH) and outcome after intravenous thrombolysis for ischemic stroke.

METHODS

We pooled data from 2 European intravenous thrombolysis registries. Statin doses were stratified in 3 groups according to the attainable lowering of cholesterol levels (low dose: simvastatin 20 mg or equivalent; medium dose: simvastatin 40 mg or equivalent; and high dose: simvastatin 80 mg or equivalent). sICH was defined according to the European Cooperative Acute Stroke Study. Modified Rankin Scale score 0 to 2 at 3 months was considered a favorable outcome.

RESULTS

Among 1446 patients analyzed (median age, 75 years; median initial National Institutes of Health Stroke Scale score, 11; 54% men), 317 (22%) used statins before intravenous thrombolysis. Of them, 120 patients had low-dose, 134 medium-dose, and 63 high-dose statin therapy. sICH occurred in 4% of patients (n=53). Frequency of sICH was 2%, 6%, and 13% in patients with low-, medium-, and high-dose statin treatment, respectively (P<0.01). Adjusted odds ratio (OR) for sICH was 2.4 (95% confidence interval [CI], 1.1-5.3) and 5.3 (95% CI, 2.3-12.3) for patients with medium- and high-dose statins compared with non-statin users. Statin users more often achieved favorable outcome compared with non-statin users (58% versus 51%; P=0.03). An independent association of statin use with favorable outcome was detected (adjusted OR, 1.8; 95% CI, 1.3-2.5). The association was maintained when stratifying for statin dose, although it was not significant in the high-dose group anymore (OR, 1.7; 95% CI, 0.9-3.2).

CONCLUSIONS

We observed an association between increasing dose of statin use and risk of sICH after intravenous thrombolysis. Nevertheless, there was an overall beneficial effect of previous statin use on favorable 3-month outcome.

Imaging Biomarkers for Intra-arterial Stroke Therapy

Despite high rates of early revascularization with intra-arterial stroke therapy, the clinical efficacy of this approach has not been clearly demonstrated. Neuroimaging biomarkers will be useful in future trials for patient selection and for outcomes evaluation. To identify patients who are likely to benefit from intra-arterial therapy, the combination of vessel imaging, infarct size quantification and degree of neurologic deficit appears critical. Perfusion imaging may be useful in specific circumstances, but requires further validation. For measuring treatment outcomes, surrogate biomarkers that appear suitable are angiographic reperfusion as measured by the modified Thrombolysis in Cerebral Infarction scale and final infarct volume.

Intravenous thrombolysis for patients with reverse magnetic resonance angiography and diffusion-weighted imaging mismatch: SAMURAI and NCVC rt-PA Registries

BACKGROUND AND PURPOSE

The characteristics of reverse magnetic resonance angiography and diffusion-weighted imaging (MRA-DWI) mismatch (RMM), defined as a large DWI lesion in the absence of major artery occlusion (MAO), remain unknown, especially in patients treated with intravenous recombinant tissue plasminogen activator (rt-PA).

METHODS

Patients with stroke in the middle cerebral artery territory were included. Early ischaemic changes (EIC) were assessed with the Alberta Stroke Program Early CT Score on DWI (DWI-ASPECTS). All patients were divided into four groups based on the presence of MAO and a DWI-ASPECTS cut-off value of <7. RMM was defined as DWI-ASPECTS <7 without MAO. Clinical characteristics, symptomatic intracerebral hemorrhage (sICH) and favorable functional outcome (modified Rankin Scale score 0-2) at 90 days were compared amongst the four groups.

RESULTS

Of the 486 patients enrolled (167 women, median age 74 years, median initial National Institutes of Health Stroke Scale score 13), reverse MRA-DWI mismatch was observed in 24 (5%). Of the clinical characteristics, cardioembolism was the only factor that was independently associated with RMM [odds ratio (OR) 5.49, 95% confidence interval (CI) 1.25-24.1]. Multivariable analyses revealed that patients with RMM more commonly had sICH than those with DWI-ASPECTS ≥ 7 irrespective of the presence (OR 5.44, 95% CI 1.13-26.1) or absence (13.1, 2.07-83.3) of MAO, and they had a more favorable functional outcome than those with DWI-ASPECTS < 7 plus MAO (7.45, 2.39-23.2).

CONCLUSION

RMM was observed in 5% of patients treated with rt-PA and associated with cardioembolism. Patients with RMM may benefit from thrombolysis compared with those with EIC with MAO, although increment in the rate of sICH is a concern.

Stent retrievers in acute ischemic stroke: complications and failures during the perioperative period

BACKGROUND AND PURPOSE

Stent retriever-assisted thrombectomy promotes high recanalization rates in acute ischemic stroke. Nevertheless, complications and failures occur in more than 10% of procedures; hence, there is a need for further investigation.

MATERIALS AND METHODS

A total of 144 patients with ischemic stroke presenting with large-vessel occlusion were prospectively included. Patients were treated with stent retriever-assisted thrombectomy ± IV fibrinolysis. Baseline clinical and imaging characteristics were incorporated in univariate and multivariate analyses. Predictors of recanalization failure (TICI 0, 1, 2a), and of embolic and hemorrhagic complications were reported. The relationship between complication occurrence and periprocedural mortality rate was studied.

RESULTS

Median age was 69.5 years, and median NIHSS score was 18 at presentation. Fifty patients (34.7%) received stand-alone thrombectomy, and 94 (65.3%) received combined therapy. The procedural failure rate was 13.9%. Embolic complications were recorded in 12.5% and symptomatic intracranial hemorrhage in 7.6%. The overall rate of failure, complications, and/or death was 39.6%. The perioperative mortality rate was 18.4% in the overall cohort but was higher in cases of failure (45%; P = .003), embolic complications (38.9%; P = .0176), symptomatic intracranial hemorrhages (45.5%; P = .0236), and intracranial stenosis (50%; P = .0176). Concomitant fibrinolytic therapy did not influence the rate of recanalization or embolic complication, or the intracranial hemorrhage rate. Age was the only significant predictive factor of intracranial hemorrhage (P = .043).

CONCLUSIONS

The rate of perioperative mortality was significantly increased in cases of embolic and hemorrhagic complications, as well as in cases of failure and underlying intracranial stenoses. Adjunctive fibrinolytic therapy did not improve the recanalization rate or collateral embolic complication rate. The rate of symptomatic intracranial hemorrhage was not increased in cases of combined treatment.

Imaging of cerebral ischemia: from acute stroke to chronic disorders

Cerebral ischemia manifests widely in patient symptoms. Along with the clinical examination, imaging serves as a powerful tool throughout the course of ischemia-from acute onset to evolution. A thorough understanding of imaging modalities, their strengths and their limitations, is essential for capitalizing on the benefit of this complementary source of information for understanding the mechanism of disease, making therapeutic decisions, and monitoring patient response over time.

Utility of early post-treatment single-photon emission computed tomography imaging to predict outcome in stroke patients treated with intravenous tissue plasminogen activator

It is important to predict the outcome of tissue plasminogen activator (tPA)-treated patients early after the treatment for considering the post-tPA treatment option. We assessed cerebral blood flow (CBF) of tPA-treated patients with single-photon emission computed tomography (SPECT) 1 hour after tPA infusion to predict the patient outcome. Technetium-99m-hexamethylpropyleneamine oxime SPECT was performed in 35 consecutive tPA-treated patients. Asymmetry index, a contralateral-to-ipsilateral ratio of CBF, was calculated to analyze CBF quantitatively. Hypoperfusion or hyperperfusion was defined as a decrease of 25% or more or a increase of 25% or more in asymmetry index, respectively. Of all 35 patients, 23 had only hypoperfusion, 8 had both hypoperfusion and hyperperfusion, 2 had only hyperperfusion, and 2 had no perfusion abnormality. When evaluating the association between hypoperfusion and outcome, hypoperfusion volumes were significantly correlated with the modified Rankin Scale at 3 months (r = .634, P < .001). Hyperperfusion was observed in 10 patients (28.6%) and they showed a marked National Institutes of Health Stroke Scale score improvement in the first 24-hour period, which were significantly greater than those of 25 patients without hyperperfusion (P = .033). Eight patients (22.9%) with intracerebral hemorrhage (ICH) were all asymptomatic. Most ICHs were located in hypoperfusion areas, and no ICH was related to hyperperfusion. The results of the present study demonstrated that hypoperfusion volume was associated with poor outcome, whereas the presence of hyperperfusion seemed to be predictive of symptom improvement but not of development of ICH. Taken together, early post-treatment SPECT imaging seems to be a useful biomarker of outcome in tPA-treated patients.

Acute stroke imaging: recent updates

Acute ischemic stroke imaging is one of the leading causes of death and disability worldwide. Neuroimaging plays a crucial role in early diagnosis and yields essential information regarding tissue integrity, a factor that remains a key therapeutic determinant. Given the widespread public health implications of stroke and central role of neuroimaging in overall management, acute stroke imaging remains a heavily debated, extensively researched, and rapidly evolving subject. There has been recent debate in the scientific community due to divided opinions on the use of CT perfusion and access-related limitations of MRI. In this paper we review and summarize recent updates relevant to acute stroke imaging and propose an imaging paradigm based on the recently available evidence.

The Massachusetts General Hospital acute stroke imaging algorithm: an experience and evidence based approach

The Massachusetts General Hospital Neuroradiology Division employed an experience and evidence based approach to develop a neuroimaging algorithm to best select patients with severe ischemic strokes caused by anterior circulation occlusions (ACOs) for intravenous tissue plasminogen activator and endovascular treatment. Methods found to be of value included the National Institutes of Health Stroke Scale (NIHSS), non-contrast CT, CT angiography (CTA) and diffusion MRI. Perfusion imaging by CT and MRI were found to be unnecessary for safe and effective triage of patients with severe ACOs. An algorithm was adopted that includes: non-contrast CT to identify hemorrhage and large hypodensity followed by CTA to identify the ACO; diffusion MRI to estimate the core infarct; and NIHSS in conjunction with diffusion data to estimate the clinical penumbra.

A multicenter, randomized, double-blind, placebo-controlled trial to test efficacy and safety of magnetic resonance imaging-based thrombolysis in wake-up stroke (WAKE-UP)

RATIONALE

In about 20% of acute ischemic stroke patients stroke occurs during sleep. These patients are generally excluded from intravenous thrombolysis. MRI can identify patients within the time-window for thrombolysis (≤4·5 h from symptom onset) by a mismatch between the acute ischemic lesion visible on diffusion weighted imaging (DWI) but not visible on fluid-attenuated inversion recovery (FLAIR) imaging.

AIMS AND HYPOTHESIS

The study aims to test the efficacy and safety of MRI-guided thrombolysis with tissue plasminogen activator (rtPA) in ischemic stroke patients with unknown time of symptom onset, e.g., waking up with stroke symptoms. We hypothesize that stroke patients with unknown time of symptom onset with a DWI-FLAIR-mismatch pattern on MRI will have improved outcome when treated with rtPA compared to placebo.

DESIGN

WAKE-UP is an investigator initiated, European, multicentre, randomized, double-blind, placebo-controlled clinical trial. Patients with unknown time of symptom onset who fulfil clinical inclusion criteria (disabling neurological deficit, no contraindications against thrombolysis) will be studied by MRI. Patients with MRI findings of a DWI-FLAIR-mismatch will be randomised to either treatment with rtPA or placebo.

STUDY OUTCOME

The primary efficacy endpoint will be favourable outcome defined by modified Rankin Scale 0-1 at day 90. The primary safety outcome measures will be mortality and death or dependency defined by modified Rankin Scale 4-6 at 90 days.

DISCUSSION

If positive, WAKE-UP is expected to change clinical practice making effective and safe treatment available for a large group of acute stroke patients currently excluded from specific acute therapy.

Advanced imaging improves prediction of hemorrhage after stroke thrombolysis

OBJECTIVE

Very low cerebral blood volume (VLCBV), diffusion, and hypoperfusion lesion volumes have been proposed as predictors of hemorrhagic transformation following stroke thrombolysis. We aimed to compare these parameters, validate VLCBV in an independent cohort using DEFUSE study data, and investigate the interaction of VLCBV with regional reperfusion.

METHODS

The EPITHET and DEFUSE studies obtained diffusion and perfusion magnetic resonance imaging (MRI) in patients 3 to 6 hours from onset of ischemic stroke. EPITHET randomized patients to tissue plasminogen activator (tPA) or placebo, and all DEFUSE patients received tPA. VLCBV was defined as cerebral blood volume<2.5th percentile of brain contralateral to the infarct. Parenchymal hematoma (PH) was defined using European Cooperative Acute Stroke Study criteria. Reperfusion was assessed using subacute perfusion MRI coregistered to baseline imaging.

RESULTS

In DEFUSE, 69 patients were analyzed, including 9 who developed PH. The >2 ml VLCBV threshold defined in EPITHET predicted PH with 100% sensitivity, 72% specificity, 35% positive predictive value, and 100% negative predictive value. Pooling EPITHET and DEFUSE (163 patients, including 23 with PH), regression models using VLCBV (p<0.001) and tPA (p=0.02) predicted PH independent of clinical factors better than models using diffusion or time to maximum>8 seconds lesion volumes. Excluding VLCBV in regions without reperfusion improved specificity from 61 to 78% in the pooled analysis.

INTERPRETATION

VLCBV predicts PH after stroke thrombolysis and appears to be a more powerful predictor than baseline diffusion or hypoperfusion lesion volumes. Reperfusion of regions of VLCBV is strongly associated with post-thrombolysis PH. VLCBV may be clinically useful to identify patients at significant risk of hemorrhage following reperfusion.

Diffusion-weighted magnetic resonance imaging may underestimate acute ischemic lesions: cautions on neglecting a computed tomography-diffusion-weighted imaging discrepancy

BACKGROUND AND PURPOSE

Diffusion-weighted imaging sometimes fails to detect early computed tomography (CT) ischemic lesions in acute ischemic stroke patients, which is termed reversed discrepancy (RD), but its clinical significance remains unclear. The incidence and factors associated with RD in acute ischemic stroke patients within 3 hours of onset were examined.

METHODS

A total of 164 consecutive patients with acute anterior circulation ischemic stroke was enrolled. All patients underwent both magnetic resonance imaging and CT within 3 hours of onset and before treatment. Their early ischemic changes were evaluated with the Alberta Stroke Program Early CT Score. RD was defined as present when the early ischemic change detected on CT was not seen on diffusion-weighted imaging.

RESULTS

RD was found in 40 patients (24%). RD group patients were older (78.7 ± 9.6 versus 74.1 ± 12.1 years; P=0.03) and had a higher admission National Institutes of Health Stroke Scale score (median, 22 versus 11; P<0.01), higher rates of atrial fibrillation (75% versus 42%; P<0.01), a higher rate of internal carotid artery/middle cerebral artery proximal occlusion (55% versus 28%; P<0.01), and lower CT-Alberta Stroke Program Early CT Score (median 5 versus 10; P<0.01) and diffusion-weighted imaging-Alberta Stroke Program Early CT Score (7 versus 9; P<0.01) than patients in the non-RD group. Multivariate logistic regression analysis demonstrated that atrial fibrillation was independently associated with the presence of RD (odds ratio, 2.47; 95% CI, 1.05-6.12).

CONCLUSIONS

RD is observed in a quarter of acute ischemic stroke patients. RD should be taken into consideration, especially in patients with atrial fibrillation, to prevent underestimating the extent of ischemic lesions.

Elderly Patients Are at Higher Risk for Poor Outcomes After Intra-Arterial Therapy

Background and Purpose—

Conflicting data exist regarding outcomes after intra-arterial therapy (IAT) in elderly stroke patients. We compare safety and clinical outcomes of multimodal IAT in elderly versus nonelderly patients and investigate differences in baseline health and disability as possible explanatory factors.

Methods—

Data from a prospectively collected institutional IAT database were analyzed comparing elderly (80 years or older) versus nonelderly patients. Baseline demographics, angiographic reperfusion (Thrombolysis in Cerebral Infarction scale score 2–3), rate of parenchymal hematoma type 2, and 90-day modified Rankin Scale scores were compared in univariate and multivariate analyses.

Results—

There were 49 elderly and 130 nonelderly patients treated between 2005 and 2010. Between the 2 cohorts, there was no significant difference in Thrombolysis in Cerebral Infarction 2 to 3 reperfusion (71% vs 75%; P =0.57), time to reperfusion ( P =0.77), or rate of parenchymal hematoma type 2 (4% vs 7%; P =0.73) after IAT. However, elderly patients had significantly lower rates of good outcome (modified Rankin Scale score 0–2: 2% vs 33%; P <0.0001) and higher mortality (59% vs 24%; P <0.0001) at 90 days. Atrial fibrillation, coronary artery disease, hypertension, hyperlipidema, and baseline disability were significantly more common in elderly patients. Adjusting for baseline disability, stroke severity, and reperfusion, elderly patients were 29-times more likely to be dependent or dead at 90 days (odds ratio, 28.7; 95% confidence interval, 3.2–255.7; P =0.003).

Conclusions—

Despite comparable rates of reperfusion and significant hemorrhage, elderly patients had worse clinical outcomes after IAT, which may relate, in part, to worse baseline health and disability. The use of IAT in the elderly should be performed after a careful analysis of the potential risks and benefits.

Presentation and outcomes of "wake-up strokes" in a large randomized stroke trial: analysis of data from the International Stroke Trial

BACKGROUND

Recent studies comparing the outcomes of wake-up stroke (WUS) and stroke while awake (SWA) patients reveal better outcomes among SWA patients, attributable in part to their higher rates of thrombolysis. Patients with WUS are largely excluded from therapy. Earlier analyses, conducted before the approval of alteplase for acute stroke, show the true divergence of natural histories between these 2 groups.

METHODS

We analyzed 17,398 patients with ischemic stroke from the International Stroke Trial and compared both presentations and outcomes between the WUS and SWA groups. Severity was assessed by level of consciousness, Oxfordshire Community Stroke Project (OCSP) stroke classification, number of neurologic deficits, and predicted probability of dependency or death. Outcomes were assessed at day 14 and at 6 months. Outcome assessments were controlled for potential confounders.

RESULTS

WUS represented 29.6% of all ischemic strokes. More severe OSCP stroke type (total anterior circulation syndrome) was less common in WUS. Although more patients with WUS were alert at presentation with a lower predicted probability of dependency, the 14-day mortality rates and rates of poor outcome at 6 months were similar between the 2 groups.

CONCLUSIONS

WUS patients comprise one quarter to one third of ischemic stroke patients. Despite their more benign presentations, they deteriorate to outcome rates similar to SWA. Although they are typically excluded from time-dependent acute interventions, patients with WUS may benefit from acute intervention to prevent this worsening natural history.

Endovascular treatment of acute ischemic stroke: current indications

Endovascular stroke therapy is an effective means of achieving reperfusion in stroke patients with proximal cerebral artery occlusions. However, current guideline recommendations express uncertainty regarding the clinical efficacy of catheter-based treatments, given the lack of supportive trial data. A critical problem is that it remains unclear which patients will benefit from endovascular therapy. As such, patient selection is likely highly variable in clinical practice. This article will review the existing data to discuss the clinical and imaging factors that are relevant to patient outcomes, and which may be used to guide endovascular treatment decisions. Anterior circulation strokes represent the primary focus of this review.

Imaging of perfusion, angiogenesis, and tissue elasticity after stroke

Blood flow interruption in a cerebral artery causes brain ischemia and induces dramatic changes of perfusion and metabolism in the corresponding territory. We performed in parallel positron emission tomography (PET) with [(15)O]H(2)O, single photon emission computed tomography (SPECT) with [(99m)Tc]hexamethylpropylene-amino-oxime ([(99m)Tc]HMPAO) and ultrasonic ultrafast shear wave imaging (SWI) during, immediately after, and 1, 2, 4, and 7 days after middle cerebral artery occlusion (MCAO) in rats. Positron emission tomography and SPECT showed initial hypoperfusion followed by recovery at immediate reperfusion, hypoperfusion at day 1, and hyperperfusion at days 4 to 7. Hyperperfusion interested the whole brain, including nonischemic areas. Immunohistochemical analysis indicated active angiogenesis at days 2 to 7, strongly suggestive that hyperperfusion was supported by an increase in microvessel density in both brain hemispheres after ischemia. The SWI detected elastic changes of cerebral tissue in the ischemic area as early as day 1 after MCAO appearing as a softening of cerebral tissue whose local internal elasticity decreased continuously from day 1 to 7. Taken together, these results suggest that hyperperfusion after cerebral ischemia is due to formation of neovessels, and indicate that brain softening is an early and continuous process. The SWI is a promising novel imaging method for monitoring the evolution of cerebral ischemia over time in animals.

Current acute stroke trials and their potential impact on the therapeutic time window

Several trials in acute stroke are underway or have been completed recently. Among the latter, ECASS 3 was a milestone regarding the extension of the rigid 3-h time window out to 4.5 h for intravenous thrombolysis with recombinant tissue plasminogen activator. Several other approaches are being tested for thrombolytic therapy, among them modern imaging-based patient selection of patients and interventional approaches. Other pharmaceutical strategies include neuroprotection, and restoration, biophysical approaches, such as near infrared laser therapy, hemodynamic augmentation, and sphenopalatine ganglion stimulation. This perspective will cover the recently completed and currently recruiting acute stroke trials with respect to their potential role in expanding the therapeutic time window for acute ischemic stroke.

Infarct Volume Is a Pivotal Biomarker After Intra-Arterial Stroke Therapy

Background and Purpose—

Pretreatment infarct volume appears to predict clinical outcome after intra-arterial therapy. To confirm the importance of infarct size in patients undergoing intra-arterial therapy, we sought to characterize the relationship between final infarct volume (FIV) and long-term functional outcome in a prospective cohort of endovascularly treated patients.

Methods—

From our prospective intra-arterial therapy database, we identified 107 patients with acute ischemic stroke with anterior circulation proximal artery occlusions who underwent final infarct imaging and had 3-month modified Rankin Scale scores. Clinical, imaging, treatment, and outcome data were analyzed.

Results—

Mean age was 66.6 years. Median admission National Institutes of Health Stroke Scale score was 17. Reperfusion (Thrombolysis In Cerebral Infarction 2A–3) was achieved in 78 (72.9%) patients. Twenty-seven (25.2%) patients achieved a 3-month good outcome (modified Rankin Scale 0–2), and 30 (28.0%) died. Median FIV was 71.4 cm 3 . FIV independently correlated with functional outcome across the entire modified Rankin Scale. In receiver operating characteristic analysis, it was the best discriminator of both good outcome (area under the curve=0.857) and mortality (area under the curve=0.772). A FIV of approximately 50 cm 3 demonstrated the greatest accuracy for distinguishing good versus poor outcome, and a FIV of approximately 90 cm 3 was highly specific for a poor outcome. The interaction term between FIV and age was the only independent predictor of good outcome ( P <0.0001). The impact of FIV was accentuated in patients <80 years.

Conclusions—

Among patients with anterior circulation acute ischemic stroke who undergo intra-arterial therapy, final infarct volume is a critical determinant of 3-month functional outcome and appears suitable as a surrogate biomarker in proof-of-concept intra-arterial therapy trials.

Outcome of MRI-based intravenous thrombolysis in carotid-T occlusion

Low recanalization rates and poor clinical outcome have been reported after intravenous thrombolysis (IV-tPA) in carotid-T occlusion (CTO). We studied clinical outcome and imaging findings of MRI-based intravenous thrombolysis in CTO. Data of patients with acute ischemic stroke and CTO treated with IV-tPA within 6 h of symptom onset based on MRI criteria were retrospectively analyzed. Vessel occlusion was defined based on MR angiography. Acute diffusion and perfusion lesion volumes and final infarct volumes after 3-7 days were delineated. The National Institutes of Health Stroke Scale (NIHSS) was used to assess the neurological deficit on admission. Recanalization was evaluated after 24 h. Clinical outcome was assessed using the modified Rankin Scale (mRS) after 90 days. Clinical and imaging data were compared to patients with middle cerebral artery main stem occlusion (MCAO). A total of 20 patients with CTO and 51 patients with MCAO were studied. Onset to treatment time, NIHSS on admission, initial diffusion and perfusion lesion volumes, and recanalization rates after 24 h were similar between groups. Final infarct volume was larger for CTO (82 vs. 30 ml, p = 0.006). Although overall outcome was not significantly different between groups (p = 0.251), independent outcome (mRS 0-2) tended to be less frequent in CTO (17 vs. 39 %), while poor outcome (mRS 4-6) appeared more common (72 vs. 43 %). The proportion of patients with good clinical outcome after intravenous thrombolysis in CTO is small. Moreover, final infarct volume is larger and clinical outcome appears to be worse compared to MCAO.

Modified ASPECTS for DWI including deep white matter lesions predicts subsequent intracranial hemorrhage

We hypothesized that extensive early ischemic changes increase subsequent intracranial hemorrhage (ICH) in patients within 3 h of onset regardless of intravenous tPA (IV-tPA). We have established a modified scoring method, ASPECTS+W, including deep white matter lesions on DWI (DWI-W) in addition to the original ASPECTS regions. We aimed to elucidate whether CT-ASPECTS, DWI-ASPECTS, and ASPECTS+W could be useful tools in helping to predict subsequent ICH in acute ischemic stroke. One-hundred sixty-four consecutive patients with anterior circulation ischemic stroke were enrolled. All patients underwent both MRI and CT within 3 h of onset. ASPECTS+W was defined as an 11-point method combining the ten ASPECTS regions and DWI-W. The relationships of CT-ASPECTS, DWI-ASPECTS, and ASPECTS+W with ICH within the initial 36 h were assessed. Thirty-six patients (22%) were treated with IV-tPA. Follow-up CT was obtained in 159 patients, and 19 (12%) developed ICH. Patients with ICH had higher baseline NIHSS scores (median, 25 vs. 13, p = 0.010), a higher rate of IV-tPA (42 vs. 20%, p = 0.041), lower CT-ASPECTS (median, 7 vs. 10, p = 0.008), lower DWI-ASPECTS (6 vs. 9, p = 0.001), lower ASPECTS+W (6 vs. 9, p = 0.001), and higher DWI-W lesions (74 vs. 47%, p = 0.048) than those without ICH. ICA or M1 proximal occlusion was more frequently seen in patients with ICH (68 vs. 32%, p = 0.004) than in those without ICH. On multivariate regression analysis, lower ASPECTS+W (OR 0.75, 95% CI 0.58–0.96, p = 0.027) and administration of IV-tPA (OR 9.13, 95% CI 2.15–46.21, p = 0.004) independently predicted ICH development. In conclusion, ASPECTS+W is a useful tool for predicting ICH development independent of IV-tPA.

The types of neurological deficits might not justify withholding treatment in patients with low total National Institutes of Health Stroke Scale scores

BACKGROUND AND PURPOSE

There is controversy regarding the threshold for treating patients with mild strokes. Physicians often withhold acute treatment in these patients if they perceive the symptoms are not going to be disabling. We tested the appropriateness of this practice by analyzing the relationship between specific neurological deficits in the National Institutes of Health Stroke Scale (NIHSS) score and long-term outcome among patients with a low total NIHSS score.

METHODS

We performed a secondary analysis on those patients enrolled in the Trial of ORG 10172 in Acute Stroke Treatment that presented within 4.5 hours of symptom onset and had a baseline NIHSS score ≤6 (n=194). We performed multivariate logistic regression analyses using very favorable outcome at 3 months as the outcome variable and each of the individual items of the baseline NIHSS examination and syndromic combinations of NIHSS scores as predictors. The analyses were adjusted for potential confounders with and without adjusting for total NIHSS score.

RESULTS

Baseline total NIHSS scores were inversely associated with very favorable outcome at 3 months. No individual NIHSS item, or syndromic combination of NIHSS scores, was independently associated with very favorable outcome in a consistent manner after accounting for confounders and collinearity.

CONCLUSIONS

The types of neurological deficits in the baseline NIHSS are not independent predictors of long-term prognosis for patients with mild stroke. These exploratory findings argue against the practice of withholding reperfusion treatment in patients with mild stroke when the types of baseline NIHSS deficits are perceived to be nondisabling.

The infarct core is well represented by the acute diffusion lesion: sustained reversal is infrequent

Diffusion-weighted imaging (DWI) is commonly used to assess irreversibly infarcted tissue but its accuracy is challenged by reports of diffusion lesion reversal (DLR). We investigated the frequency and implications for mismatch classification of DLR using imaging from the EPITHET (Echoplanar Imaging Thrombolytic Evaluation Trial) and DEFUSE (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution) studies. In 119 patients (83 treated with IV tissue plasminogen activator), follow-up images were coregistered to acute diffusion images and the lesions manually outlined to their maximal visual extent in diffusion space. Diffusion lesion reversal was defined as voxels of acute diffusion lesion that corresponded to normal brain at follow-up (i.e., final infarct, leukoaraiosis, and cerebrospinal fluid (CSF) voxels were excluded from consideration). The appearance of DLR was visually checked for artifacts, the volume calculated, and the impact of adjusting baseline diffusion lesion volume for DLR volume on perfusion-diffusion mismatch analyzed. Median DLR volume reduced from 4.4 to 1.5 mL after excluding CSF/leukoaraiosis. Visual inspection verified 8/119 (6.7%) with true DLR, median volume 2.33 mL. Subtracting DLR from acute diffusion volume altered perfusion-diffusion mismatch (T(max)>6 seconds, ratio>1.2) in 3/119 (2.5%) patients. Diffusion lesion reversal between baseline and 3 to 6 hours DWI was also uncommon (7/65, 11%) and often transient. Clinically relevant DLR is uncommon and rarely alters perfusion-diffusion mismatch. The acute diffusion lesion is generally a reliable signature of the infarct core.

Imaging-based treatment selection for intravenous and intra-arterial stroke therapies: a comprehensive review

Reperfusion therapy is the only approved treatment for acute ischemic stroke. The current approach to patient selection is primarily based on the time from stroke symptom onset. However, this algorithm sharply restricts the eligible patient population, and neglects large variations in collateral circulation that ultimately determine the therapeutic time window in individual patients. Time alone is unlikely to remain the dominant parameter. Alternative approaches to patient selection involve advanced neuroimaging methods including MRI diffusion-weighted imaging, magnetic resonance and computed tomography perfusion imaging and noninvasive angiography that provide potentially valuable information regarding the state of the brain parenchyma and the neurovasculature. These techniques have now been used extensively, and there is emerging evidence on how specific imaging data may result in improved clinical outcomes. This article will review the major studies that have investigated the role of imaging in patient selection for both intravenous and intra-arterial therapies.

Hyperdensity on non-contrast CT immediately after intra-arterial revascularization

Non-contrast enhanced computed tomography (NCCT) is usually performed to estimate bleeding complications immediately after procedures. However, hyperdense areas on NCCT have not yet been understood; different interpretations have been reported in the literature. It remains unclear whether NCCT performed immediately after intra-arterial revascularization (IAR) could be useful for predicting hemorrhagic transformation (HT) or clinical outcomes. Therefore, we investigated the diagnostic values of hyperdense areas on NCCT images obtained immediately after IAR. This was a retrospective study of acute ischemic stroke patients who underwent IAR between October 2007 and December 2010. NCCT scans were routinely obtained immediately after IAR and additional follow-up imaging protocols included diffusion weighted imaging (DWI)/gradient echo imaging (GRE) 24 h after IAR. HT was assessed by means of GRE obtained 24 h after IAR. Hounsfield Unit (HU) of the hyperdensity was measured in the manually drawn regions of interest. A total of 68 patients were analyzed in this study. Twenty-nine patients (42.6%) developed HT on follow-up images. Thirty-eight patients had hyperdense areas on NCCT immediately after IAR. Hyperdensity on NCCT performed immediately after IAR revealed 23 (60.5%) of the 38 patients with six false negative areas. NCCT performed immediately after IAR showed a sensitivity of 79.3%, a specificity of 61.5%, a positive predictive value of 60.5% and a negative predictive value of 80% for HT. The HU value was a predictor of HT without statistical significance (area under curve of 0.629; 95% CI: 0.49-0.76; p = 0.068). In addition, an HU of >90 poorly predicted HT with a low sensitivity (23%) and a high specificity (94%). In conclusion, our results showed that although hyperdensity on NCCT images obtained immediately after IAR had a moderate predictive value for HT, there were limitations to the prediction of subsequent parenchymal hematoma and symptomatic intracranial hemorrhage, with a low specificity and a low positive predictive value.

Fluid-attenuated inversion recovery hyperintensity in acute ischemic stroke may not predict hemorrhagic transformation

BACKGROUND

Fluid-attenuated inversion recovery (FLAIR) hyperintensity within an acute cerebral infarct may reflect delayed onset time and increased risk of hemorrhage after thrombolysis. Given the important implications for clinical practice, we examined the prevalence of FLAIR hyperintensity in patients 3-6 h from stroke onset and its relationship to parenchymal hematoma (PH).

METHODS

Baseline DWI and FLAIR imaging with subsequent hemorrhage detection (ECASS criteria) were prospectively obtained in patients 3-6 h after stroke onset from the pooled EPITHET and DEFUSE trials. FLAIR hyperintensity within the region of the acute DWI lesion was rated qualitatively (dichotomized as visually obvious or subtle (i.e. only visible after careful windowing)) and quantitatively (using relative signal intensity (RSI)). The association of FLAIR hyperintensity with hemorrhage was then tested alongside established predictors (very low cerebral blood volume (VLCBV) and diffusion (DWI) lesion volume) in logistic regression analysis.

RESULTS

There were 49 patients with pre-treatment FLAIR imaging (38 received tissue plasminogen activator (tPA), 5 developed PH). FLAIR hyperintensity within the region of acute DWI lesion occurred in 48/49 (98%) patients, was obvious in 18/49 (37%) and subtle in 30/49 (61%). Inter-rater agreement was 92% (κ = 0.82). The prevalence of obvious FLAIR hyperintensity did not differ between studies obtained in the 3-4.5 h and 4.5-6 h time periods (40% vs. 33%, p = 0.77). PH was poorly predicted by obvious FLAIR hyperintensity (sensitivity 40%, specificity 64%, positive predictive value 11%). In univariate logistic regression, VLCBV (p = 0.02) and DWI lesion volume (p = 0.03) predicted PH but FLAIR lesion volume (p = 0.87) and RSI (p = 0.11) did not. In ordinal logistic regression for hemorrhage grade adjusted for age and baseline stroke severity (NIHSS), increased VLCBV (p = 0.002) and DWI lesion volume (p = 0.003) were associated with hemorrhage but FLAIR lesion volume (p = 0.66) and RSI (p = 0.35) were not.

CONCLUSIONS

Visible FLAIR hyperintensity is almost universal 3-6 h after stroke onset and did not predict subsequent hemorrhage in this dataset. Our findings question the value of excluding patients with FLAIR hyperintensity from reperfusion therapies. Larger studies are required to clarify what implications FLAIR-positive lesions have for patient selection.

Clinical applications of diffusion MR imaging for acute ischemic stroke

Diffusion magnetic resonance imaging is the best imaging tool for detecting acute ischemic brain injury. Studies have shown its high accuracy for delineating irreversible tissue damage within the first few hours after stroke onset; however, the true value of any diagnostic tool is whether it can be used to guide clinical management. This review discusses the role of diffusion imaging in the evaluation of the patient with acute ischemic stroke, and how this role is influenced by other important stroke-related variables, including the level of vessel occlusion and the clinical deficit. The review focuses on decision-making for intravenous and intra-arterial reperfusion therapies.

Acute stroke thrombolysis: time to dispense with the clock and move to tissue-based decision making?

Currently, imaging is predominantly used to exclude patients for thrombolysis, rather than identify patients most likely to benefit. This means that patients are being selected for treatment without reference to tissue pathophysiology. Imaging of specific stroke pathophysiology may be the key to selecting patients most likely to benefit from thrombolysis, and could revolutionize acute stroke assessment and treatment. The technology is available to identify the acute infarct core and possibly the penumbra, via magnetic resonance diffusion-weighted imaging, and both magnetic resonance- and computed tomography-perfusion imaging techniques. However, these modalities require fine tuning before they can be reliably implemented in a routine clinical setting.

Leukoaraiosis on magnetic resonance imaging is related to long-term poor functional outcome after thrombolysis in acute ischemic stroke

OBJECTIVE

Leukoaraiosis (LA) has been suggested to be related to the poor outcome or the occurrence of symptomatic intracerebral hemorrhage (sICH) after acute ischemic stroke. We retrospectively investigated the influences of LA on long-term outcome and the occurrence of sICH after thrombolysis in acute ischemic stroke (AIS).

METHODS

In this study, we recruited 164 patients with AIS and magnetic resonance image (MRI)-detected thrombolysis. The presence and extent of LA were assessed using the Fazekas grading system. The National Institutes of Health Stroke Scale score was used to assess the baseline measure of neurologic severity, and the modified Rankin Scale score assessment was used up to 1 year after thrombolysis.

RESULTS

Of 164 subjects, 56 (34.2%) showed LA on MRI. Compared to the 108 patients without LA, the patients with LA were of much older age (p<0.01), had a higher prevalence of hypertension (p<0.01), and had a much poorer outcome at 90 days (p=0.05) and 1 yr (p=0.01) after thrombolysis. There were no significant differences in sICH between patients with and without LA on MRI. In univariate analysis for the occurrence of poor outcome at 90 days after thrombolysis, the size of ischemic lesion on diffusion weighted images (DWI), [odds ratio (OR), 1.03; 95% confidence interval (95% CI), 1.01-1.04; p<0.01], recanalization (OR, 0.03; 95% CI, 0.01-0.10; p<0.01), sICH (OR, 12.2; 95% CI, 1.54-95.8), neurologic severity (OR, 1.17; 95% CI, 1.09-1.25; p<0.01), blood glucose level (OR, 1.01; 95% CI, 1.00-1.02; p=0.03), and the presence of LA on MRI (OR, 2.01; 95% CI, 1.04-3.01; p=0.04) were statistically significant. In multivariate analysis, neurologic severity (OR, 1.14; 95% CI, 1.04-1.24; p<0.01), recanalization (OR, 0.03; 95% CI, 0.01-0.11; p<0.01), lesion size on DWI (OR, 1.02; 95% CI, 1.01-1.03; p=0.02), serum glucose level (OR, 1.01; 95% CI; 1.01-1.02; p=0.03), and the presence of LA on MRI (OR, 3.2; 95% CI, 1.22-8.48; p<0.01) showed statistically significant differences. These trends persisted up to 1 yr after thrombolysis.

CONCLUSION

In this study, we demonstrated that the presence of LA on MRI might be related to poor outcome after use of intravenous tissue plasminogen activator in AIS.

Brain imaging in stroke: insight beyond diagnosis

Stroke, whether hemorrhagic or ischemic in nature, has the ability to lead to devastating and debilitating patient outcomes, which not only has direct implications from a healthcare standpoint, but its effects are longstanding and they impact the community as a whole. For decades, the goal of advancement and refinement in imaging modalities has been to develop the most precise, convenient, widely available and reproducible interpretable modality for the detection of stroke, not only in its hyperacute phase, but a method to be able to predict its evolution through the natural course of disease. Diagnosis is one of the most important initial roles, which imaging fulfills after the identification of existent pathology. However, imaging fulfills an even more important goal by using a combination of imaging modalities and their precise interpretation, which lends itself to understanding the mechanisms and pathophysiology of underlying disease, and therefore guides therapeutic decision-making in a patient-tailored fashion. This review explores the most commonly used brain imaging modalities, computer tomography, and magnetic resonance imaging, with an aim to demonstrate their dynamic use in uncovering stroke mechanism, facilitating prognostication, and potentially guiding therapy.

Improving reperfusion therapy for acute ischaemic stroke

BACKGROUND

The first generation of clinical reperfusion treatment, intravenous (IV) fibrinolysis with tissue plasminogen activator (tPA), was a transformative breakthrough in stroke care, but is far from ideal.

OBJECTIVES

TO survey emerging strategies to increase the efficacy and safety of cerebral reperfusion therapy.

METHODS

Narrative review.

RESULTS AND CONCLUSIONS

Innovative IV pharmacologic reperfusion strategies include: extending IV tPA use to patients with mild deficits; developing novel fibrinolytic agents (tenecteplase, desmetolplase, plasmin); using ultrasound to enhance enzymatic fibrinolysis; combination clot lysis therapies (fibrinolytics with GPIIb/IIIa agents or direct thrombin inhibitors); co-administration of MMP-9 inhibitors to deter haemorrhagic transformation; and prehospital neuroprotection to support threatened tissues until reperfusion. Endovascular recanalisation strategies are rapidly evolving, and include intra-arterial fibrinolysis, mechanical clot retrieval, suction thrombectomy, and primary stenting. Combined approaches appear especially promising, using IV fibrinolysis to rapidly initiate reperfusion, mechanical endovascular treatment to debulk large, proximal thrombi, and intra-arterial (IA) fibrinolysis to clear residual distal thrombus elements and emboli.

Advanced neuroimaging in acute ischemic stroke: extending the time window for treatment

Early treatment of ischemic stroke with thrombolytics is associated with improved outcomes, but few stroke patients receive thrombolytic treatment in part due to the 3-hour time window. Advances in neuroimaging may help to aid in the selection of patients who may still benefit from thrombolytic treatment beyond conventional time-based guidelines. In this article the authors review the available literature in support of using advanced neuroimaging to select patients for treatment beyond the 3-hour time window cutoff and explore potential applications and limitations of perfusion imaging in the treatment of acute ischemic stroke.

RAPID automated patient selection for reperfusion therapy: a pooled analysis of the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) and the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution (DEFUSE) Study

BACKGROUND AND PURPOSE

The aim of this study was to determine if automated MRI analysis software (RAPID) can be used to identify patients with stroke in whom reperfusion is associated with an increased chance of good outcome.

METHODS

Baseline diffusion- and perfusion-weighted MRI scans from the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution study (DEFUSE; n=74) and the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET; n=100) were reprocessed with RAPID. Based on RAPID-generated diffusion-weighted imaging and perfusion-weighted imaging lesion volumes, patients were categorized according to 3 prespecified MRI profiles that were hypothesized to predict benefit (Target Mismatch), harm (Malignant), and no effect (No Mismatch) from reperfusion. Favorable clinical response was defined as a National Institutes of Health Stroke Scale score of 0 to 1 or a ≥ 8-point improvement on the National Institutes of Health Stroke Scale score at Day 90.

RESULTS

In Target Mismatch patients, reperfusion was strongly associated with a favorable clinical response (OR, 5.6; 95% CI, 2.1 to 15.3) and attenuation of infarct growth (10 ± 23 mL with reperfusion versus 40 ± 44 mL without reperfusion; P<0.001). In Malignant profile patients, reperfusion was not associated with a favorable clinical response (OR, 0.74; 95% CI, 0.1 to 5.8) or attenuation of infarct growth (85 ± 74 mL with reperfusion versus 95 ± 79 mL without reperfusion; P=0.7). Reperfusion was also not associated with a favorable clinical response (OR, 1.05; 95% CI, 0.1 to 9.4) or attenuation of lesion growth (10 ± 15 mL with reperfusion versus 17 ± 30 mL without reperfusion; P=0.9) in No Mismatch patients.

CONCLUSIONS

MRI profiles that are associated with a differential response to reperfusion can be identified with RAPID. This supports the use of automated image analysis software such as RAPID for patient selection in acute stroke trials.

Role of diffusion and perfusion MRI in selecting patients for reperfusion therapies

After onset of ischemic stroke, potentially viable tissue at risk (ischemic penumbra) may be salvageable. Currently, intravenous alteplase is approved for up to 4.5 hours after symptom onset of acute ischemic stroke. Increasing this time window may allow many more patients to be treated. The ability to use MRI to help define the irreversibly damaged brain (infarct core) and the reversible ischemic penumbra shows great promise for stroke treatment. Recent advances in penumbral imaging technology may enable a phase III trial of an intravenous thrombolytic to be performed beyond 4.5 hours using techniques to select patients with penumbral tissue.

Nontraumatic intracranial hemorrhage

Nontraumatic (or spontaneous) intracranial hemorrhage most commonly involves the brain parenchyma and subarachnoid space. This entity accounts for at least 10% of strokes and is a leading cause of death and disability in adults. Important causes of spontaneous intracranial hemorrhage include hypertension, cerebral amyloid angiopathy, aneurysms, vascular malformations, and hemorrhagic infarcts (both venous and arterial). Imaging findings in common and less common causes of spontaneous intracranial hemorrhage are reviewed.

Mechanical thrombectomy with the Penumbra recanalization device in acute ischemic stroke

BACKGROUND AND PURPOSE

The aim of this study was to assess the clinical outcome of patients treated with the Penumbra system (PS) for acute ischemic stroke. A retrospective, monocentric matched-pair analysis in comparison with patients treated by intraarterial thrombolysis (IAT) with alteplase was designed for this purpose.

METHODS

Twenty-two consecutive patients, (mean age 62), with acute ischemic stroke and National Institutes of Health Stroke Scale (NIHSS) scores ≥ 7 were treated with the PS. Twenty corresponding patients could be identified, treated with IAT. Matches were sought for initial NIHSS score and target vessels. Thrombolysis in myocardial infarction (TIMI) grades, mortality rates, NIHSS upon discharge, and modified Rankin scores (mRs) at 90 days were compared.

RESULTS

A total of 32 vessels in 20 patients were treated in either arm of the study. Recanalization to TIMI 2/3 was successful in 25/32 (78%) of target vessels with the PS, and 17/32 (53%) of target vessels in the IAT group. Upon discharge, 2/20 patients treated with PS and 7/20 patients treated with IAT had a NIHSS score of 0 to 1 or an improvement greater or equal to 10-point on the NIHSS scale. All cause mortality at 90 days was 3/20 patients treated with PS, and 2/20 patients treated with IAT. Three out of twenty patients treated with PS and 7/20 patients treated with IAT had a mRS of ≤ 2 at 90 days.

CONCLUSION

The Penumbra system is effective in re-opening occluded major arteries. Our data seems to indicate that not all patients benefit clinically from improved revascularization of occluded major arteries.

Postthrombolysis hemorrhage risk is affected by stroke assessment bias between hemispheres

OBJECTIVE

Stroke symptoms in right hemispheric stroke tend to be underestimated in clinical assessment scales, resulting in greater infarct volumes in right as compared to left hemispheric strokes despite similar clinical stroke severity. We hypothesized that patients with right hemispheric nonlacunar stroke are at higher risk for secondary intracerebral hemorrhage after thrombolysis despite similar stroke severity.

METHODS

We analyzed data of 2 stroke cohorts with CT-based and MRI-based imaging before thrombolysis. Initial stroke severity was measured with the NIH Stroke Scale (NIHSS). Lacunar strokes were excluded through either the presence of cortical symptoms (CT cohort) or restriction to patients with prestroke diffusion-weighted imaging (DWI) lesion size >3.75 mL (MRI cohort). Probabilities of having a parenchymal hematoma were determined using multivariate logistic regression.

RESULTS

A total of 392 patients in the CT cohort and 400 patients in the MRI cohort were evaluated. Although NIHSS scores were similar in strokes of both hemispheres (median NIHSS: CT: 15 vs 13, MRI: 14 vs 16), the frequencies of parenchymal hematoma were higher in right hemispheric compared to left hemispheric strokes (CT: 12.4% vs 5.7%, MRI: 10.4% vs 6.8%). After adjustment for potential confounders (but not pretreatment lesion volume), the probability of parenchymal hematoma was higher in right hemispheric nonlacunar strokes (CT: odds ratio [OR] 2.3; 95% confidence interval [CI] 1.08-4.89; p = 0.032) and showed a borderline significant effect in the MRI cohort (OR 2.1; 95% CI 0.98-4.49; p = 0.057). Adjustment for pretreatment DWI lesion size eliminated hemispheric differences in hemorrhage risk.

CONCLUSIONS

Higher hemorrhage rates in right hemispheric nonlacunar strokes despite similar stroke severity may be caused by clinical underestimation of the proportion of tissue at bleeding risk.