Specific DWI lesion patterns predict prognosis after acute ischaemic stroke within the MCA territory

Cerebral hemodynamics and stroke risks in symptomatic intracranial atherosclerotic stenosis with internal versus cortical borderzone infarcts: A computational fluid dynamics study

There may be different mechanisms underlying internal (IBZ) and cortical (CBZ) borderzone infarcts in intracranial atherosclerotic stenosis. In 84 patients with symptomatic, 50-99% atherosclerotic stenosis of M1 middle cerebral artery (MCA-M1) with acute borderzone infarcts in diffusion-weighted imaging, we classified the infarct patterns as isolated IBZ (n = 37), isolated CBZ (n = 31), and IBZ+CBZ (n = 16) infarcts. CT angiography-based computational fluid dynamics models were constructed to quantify translesional, post-stenotic to pre-stenotic pressure ratio (PR) in the MCA-M1 lesion. Those with IBZ infarcts were more likely to have a low PR (indicating impaired antegrade flow across the lesion) than those without (p = 0.012), and those with CBZ infarcts were more likely to have coexisting small cortical infarcts (indicating possible embolism) than those without (p = 0.004). In those with isolated IBZ or CBZ infarcts, low PR was independently associated with isolated IBZ infarcts (adjusted odds ratio = 4.223; p = 0.026). These two groups may also have different trajectories in the stroke risks under current medical treatment regimen, with a higher risk of same-territory ischemic stroke recurrence within 3 months in patients with isolated IBZ infarcts than isolated CBZ infarcts (17.9% versus 0.0%; log-rank p = 0.023), but similar risks later in 1 year.

Stroke mechanisms in adult moyamoya disease: The association between infarction patterns and quantitative magnetic resonance angiography flow state

INTRODUCTION

Flow augmentation is the mainstay treatment for moyamoya disease as hemodynamic failure is believed to be the dominant mechanism. We aimed to investigate the mechanisms of stroke in moyamoya disease by assessing the relationship between infarction patterns and quantitative magnetic resonance angiography flow state.

METHODS

A retrospective study of adult patients with suspected MMD who presented with MRI confirmed acute ischemic stroke predating or following QMRA by a maximum of six months between 2009 and 2021 was conducted. Of the 177 consecutive patients with MMD who received QMRA, 35 patients, consisting of 41 hemispheres, met inclusion criteria. Flow-status was dichotomized into low-flow and normal-flow state based on previously established criteria.

RESULTS

Mixed infarction pattern was the most frequent finding (70.7 %), followed by embolic (17.1 %), perforator (7.3 %), and internal borderzone (IBZ) (4.9 %). Infarction patterns were further dichotomized into IBZ+ (internal borderzone alone or mixed) and IBZ- (no internal borderzone constituent). Low-flow states were not significantly more frequent in the IBZ+ compared to IBZ- population (48.4 % vs. 20.0 %, p = 0.14). Ipsilateral posterior cerebral artery fractional flow was significantly higher with IBZ+ compared to IBZ- (345.0 % vs. 214.7 %, p = 0.04).

CONCLUSION

Mixed infarction pattern was the most common pattern of infarction in patients with moyamoya disease, implying hypoperfusion and thromboembolism are codominant stroke mechanisms. An association between ICA flow status and infarction pattern was not found, although QMRA evidence of more robust posterior cerebral artery leptomeningeal collaterals was found in patients with a hypoperfusion contribution to their stroke mechanism.

Identification of magnetic resonance imaging features for the prediction of unrecognized atrial fibrillation in acute ischemic stroke

Background and purpose

The early identification of cardioembolic stroke is critical for the early initiation of anticoagulant treatment. However, it can be challenging to identify the major cardiac source, particularly since the predominant source, paroxysmal atrial fibrillation (AF), may not be present at the time of stroke. In this study, we aimed to evaluate imaging predictors for unrecognized AF in patients with acute ischemic stroke.

Methods

We performed a cross-sectional analysis of data and magnetic resonance imaging (MRI) scans from two prospective cohorts of patients who underwent serial 12-lead electrocardiography and 24-h Holter monitoring to detect unrecognized AF. The imaging patterns in diffusion-weighted imaging and imaging characteristics were assessed and classified. A logistic regression model was used to identify predictive factors for newly detected AF in patients with acute ischemic stroke.

Results

A total of 734 patients were recruited for analysis, with a median age of 72 (interquartile range: 65–79) years and a median National Institutes of Health Stroke Scale score of 4 (interquartile range: 2–6). Of these patients, 64 (8.7%) had newly detected AF during the follow-up period. Stepwise multivariate logistic regression revealed that age ≥75 years [adjusted odds ratio (aOR) 5.66, 95% confidence interval (CI) 2.98–10.75], receiving recombinant tissue plasminogen activator treatment (aOR 4.36, 95% CI 1.65–11.54), congestive heart failure (aOR 6.73, 95% CI 1.85–24.48), early hemorrhage in MRI (aOR 3.62, 95% CI 1.52–8.61), single cortical infarct (aOR 6.49, 95% CI 2.35–17.92), and territorial infarcts (aOR 3.54, 95% CI 1.06–11.75) were associated with newly detected AF. The C-statistic of the prediction model for newly detected AF was 0.764.

Conclusion

Initial MRI at the time of stroke may be useful to predict which patients have cardioembolic stroke caused by unrecognized AF. Further studies are warranted to verify these findings and their application to high-risk patients.

A nomogram for predicting the in-hospital risk of recurrence among patients with minor non-cardiac stroke

BACKGROUND

Patients with minor stroke suffer a substantial risk of further recurrences, especially in the first two weeks. We aimed to develop and validate a prognostic nomogram to predict in-hospital stroke recurrence among patients with acute minor stroke.

METHODS

A total of 1326 patients with minor non-cardiac stroke (NIHSS) ≤5) from three centers were divided into development cohort (1016 patients from two centers) and validation cohort (310 patients from another center). Recurrent stroke was defined as a new ischemic stroke. A logistic regression model was employed to develop the nomogram to predict in-hospital stroke recurrence in patients with minor stroke using demographic, medical and imaging information. We then validated the nomogram externally. The predictive discrimination and calibration of the nomogram were assessed in the development and validation cohorts by area under the curve (AUC) and calibration plots.

RESULTS

During a median length of stay of 12 days, stroke recurrence occurred in 34 patients (3.3%). Predictors of in-hospital recurrence included prior history of transient ischemic attack, baseline NIHSS score, multiple infarctions, and carotid stenosis. The clinical and imaging-based nomogram B demonstrated adequate calibration and discrimination (AUC = 0.777), which was validated among 273 patients in a separate validation cohort (AUC = 0.753). Our clinical-imaging based nomogram was determined to be superior to the clinical-based nomogram and the RRE90 score in terms of discrimination.

CONCLUSION

A prognostic nomogram that integrates clinical and imaging information to predict the in-hospital risk of stroke recurrence among patients after acute minor stroke was constructed and validated externally. The nomogram demonstrated adequate calibration and discrimination in both the development and validation cohort.

Vertebrobasilar Stroke: Association Between Infarction Patterns and Quantitative Magnetic Resonance Angiography Flow State

Background

Treatment and prognosis of vertebrobasilar atherosclerotic disease differs depending on stroke mechanism, such as artery‐to‐artery embolism, branch atheromatous disease, and hemodynamic ischemia. Our aim was to investigate the relationship between infarction pattern and flow status using quantitative magnetic resonance angiography (QMRA), to determine the validity of using infarction patterns to infer stroke mechanism.

Methods and Results

This is a retrospective study of patients with ischemic stroke with intra‐ or extracranial vertebrobasilar atherosclerotic stenosis, who underwent magnetic resonance imaging of the brain, neurovascular imaging, and QMRA, between 2009 and 2021. Patients with cerebral infarction predating or following QMRA by ≥1 year, or QMRA studies performed for basilar thrombosis, vertebral dissection, or only postangioplasty/stenting, were excluded. Poststenotic flow (basilar and posterior cerebral arteries) was dichotomized as low‐flow or normal‐flow based on published criteria. Of 1211 consecutive patients who underwent QMRA noninvasive optimal analysis, 69 met inclusion. Mixed patterns were most common (46.4%), followed by perforator (23.2%), borderzone (14.5%), and territorial (15.9%). Patients with low‐flow had a significantly higher rate of borderzone+ patterns (borderzone alone or in mixed pattern) compared with patients with normal‐flow (77.4% low‐flow versus 39.5% normal‐flow, P=0.002). Borderzone+ patterns were associated with 61.5% probability of low‐flow state, while no borderzone (perforator/territorial) patterns were associated with 76.7% probability of normal‐flow state.

Conclusions

Borderzone infarction pattern (alone or mixed) was associated with low poststenotic posterior circulation flow by QMRA. However, borderzone pattern only moderately predicted low‐flow state, and may be an unreliable flow marker. Therefore, infarct topography may complement, but should not replace hemodynamic studies to establish flow status.

Validation of CSR model to predict stroke risk after transient ischemic attack

It is essential to identify high risk transient ischemic attack (TIA) patients. The previous study reported that the CSR (comprehensive stroke recurrence) model, a neuroimaging model, had a high predictive ability of recurrent stroke. The aims of this study were to validate the predictive value of CSR model in TIA patients and compare the predictive ability with ABCD³-I score. Data were analyzed from the prospective hospital-based database of patients with TIA which defined by the World Health Organization time-based criteria. The predictive outcome was stroke occurrence at 90 days. The receiver-operating characteristic (ROC) curves were plotted and the C statistics were calculated as a measure of predictive ability. Among 1186 eligible patients, the mean age was 57.28 ± 12.17 years, and 474 (40.0%) patients had positive diffusion-weighted imaging (DWI). There were 118 (9.9%) patients who had stroke within 90 days. In 1186 TIA patients, The C statistic of CSR model (0.754; 95% confidence interval [CI] 0.729–0.778) was similar with that of ABCD³-I score (0.717; 95% CI 0.691–0.743; Z = 1.400; P = 0.1616). In 474 TIA patients with positive DWI, C statistic of CSR model (0.725; 95% CI 0.683–0.765) was statistically higher than that of ABCD³-I score (0.626; 95% CI 0.581–0.670; Z = 2.294; P = 0.0245). The CSR model had good predictive value for assessing stroke risk after TIA, and it had a higher predictive value than ABCD³-I score for assessing stroke risk for TIA patients with positive DWI.

Borderzone Infarction and Small Vessel Disease in a Sample of Egyptian Stroke Patients: Differences and Similarities

Background

The anatomical location of white matter hyperintense lesions in small vessel disease are apparently similar to those of borderzone infarction. The objective of this study is to find clinical and radiological points of differentiation between the two vascular disorders in a sample of Egyptian patients which might have an impact on primary and secondary prevention.

Methods

Ischemic stroke patients with white matter lesions were categorized into two groups: small vessel disease and borderzone infarctions. NIHSS was done on admission. Risk factor profile was reported, and investigations done including: HbA1C, lipid profile, CRP, ECG, echocardiography, carotid duplex, brain MRI, MRA and MR perfusion study.

Results

46 patients completed the study, 29 with SVD and 17 with BZI. Smoking, hypertension and recurrent stroke were more common in borderzone infarctions, but only diabetes was significantly higher (p = 0.047). Limb shaking was more observed in borderzone infarctions (p = 0.049). Radiologically: lacunar pattern was observed more in small vessel disease, while rosary pattern was more in borderzone infarctions (p = 0.04). FLAIR symmetrical lesions and microbleeds were more significant in small vessel disease (p = <0.001; 0.048, respectively). Perfusion study time to peak denoted evidence of significant hypoperfusion in all regions of interest in borderzone infarctions.

Conclusion

Limb shaking, retinal claudication or syncope, with MRI showing rosary pattern of white matter hyperintensity, few microbleeds and markedly impaired perfusion favor the diagnosis of borderzone infarctions. On the other hand, presence of lacunae, FLAIR showing symmetrical WMH and microbleeds with minimal or no perfusion deficit suggests the diagnosis of small vessel disease.

Imaging Pattern and Outcome of Stroke in Patients With Systemic Lupus Erythematosus: A Case-control Study

Objective

To evaluate the outcome of stroke in patients with systemic lupus erythematosus (SLE).

Methods

Patients who fulfilled ≥ 4 American College of Rheumatology criteria for SLE and had a history of stroke from 1997 to 2017 were identified. The functional outcome of stroke [assessed by the modified Rankin Scale (mRS) at 90 days], mortality, stroke complications, and recurrence were retrospectively studied and compared with matched non-SLE patients with stroke.

Results

Forty SLE patients and 120 non-SLE patients with stroke (age at stroke 44.7 ± 13.7 yrs, 87.5% women) were studied. Ischemic type of stroke (90% vs 63%, P = 0.001) and extensive infarction (69.4% vs 18.7%, P < 0.001) were more common in SLE than non-SLE patients. Border zone infarct and multiple infarcts on imaging were significantly more prevalent in SLE patients. Patients with SLE were more functionally dependent than controls at 90 days poststroke. Logistic regression showed that SLE was significantly associated with a poor stroke functional outcome independent of age, sex, past stroke, atherosclerotic risk factors, and the severity of stroke (OR 5.4, 95% CI 1.1–26.0, P = 0.035). Stroke mortality at 30 days was nonsignificantly higher in SLE than non-SLE patients, but all-cause mortality (37.5% compared to 8.3%, P < 0.001), recurrence of stroke (30% compared to 9.2%, P = 0.002), and poststroke seizure (22.5% compared to 3.3%, P = 0.001) were significantly more common in SLE patients after an observation of 8.4 ± 6.1 years. SLE was independently associated with all-cause mortality and stroke recurrence over time.

Conclusions

Stroke in patients with SLE is associated with a poorer outcome than matched controls in terms of functional recovery, recurrence, and mortality.

Quantifying the Impact of Chronic Ischemic Injury on Clinical Outcomes in Acute Stroke With Machine Learning

Acute stroke is often superimposed on chronic damage from previous cerebrovascular events. This background will inevitably modulate the impact of acute injury on clinical outcomes to an extent that will depend on the precise anatomical pattern of damage. Previous attempts to quantify such modulation have employed only reductive models that ignore anatomical detail. The combination of automated image processing, large-scale data, and machine learning now enables us to quantify the impact of this with high-dimensional multivariate models sensitive to individual variations in the detailed anatomical pattern. We introduce and validate a new automated chronic lesion segmentation routine for use with non-contrast CT brain scans, combining non-parametric outlier-detection score, Zeta, with an unsupervised 3-dimensional maximum-flow, minimum-cut algorithm. The routine was then applied to a dataset of 1,704 stroke patient scans, obtained at their presentation to a hyper-acute stroke unit (St George's Hospital, London, UK), and used to train a support vector machine (SVM) model to predict between low (0-2) and high (3-6) pre-admission and discharge modified Rankin Scale (mRS) scores, quantifying performance by the area under the receiver operating curve (AUROC). In this single center retrospective observational study, our SVM models were able to differentiate between low (0-2) and high (3-6) pre-admission and discharge mRS scores with an AUROC of 0.77 (95% confidence interval of 0.74-0.79), and 0.76 (0.74-0.78), respectively. The chronic lesion segmentation routine achieved a mean (standard deviation) sensitivity, specificity and Dice similarity coefficient of 0.746 (0.069), 0.999 (0.001), and 0.717 (0.091), respectively. We have demonstrated that machine learning models capable of capturing the high-dimensional features of chronic injuries are able to stratify patients-at the time of presentation-by pre-admission and discharge mRS scores. Our fully automated chronic stroke lesion segmentation routine simplifies this process, and utilizes routinely collected CT head scans, thereby facilitating future large-scale studies to develop supportive clinical decision tools.

Boundary and vulnerability estimation of the internal borderzone using ischemic stroke lesion mapping

Distinction between deep and superficial middle cerebral artery (MCA) territories and their junctional vascular area (the internal borderzone or IBZ) constitutes a predictor of stroke patient outcome. However, the IBZ boundaries are not well-defined because of substantial anatomical variance. Here, we built a statistical estimate of the IBZ and tested its vulnerability to ischemia using an independent sample. First, we used delineated lesions of 122 patients suffering of chronic ischemic stroke grouped in deep, superficial and territorial topographies and statistical comparisons to generate a probabilistic estimate of the IBZ. The IBZ extended from the insular cortex to the internal capsule and the anterior part of the caudate nucleus head. The IBZ showed the highest lesion frequencies (~30% on average across IBZ voxels) in our chronic stroke patients but also in an independent sample of 87 acute patients. Additionally, the most important apparent diffusion coefficient reductions (−6%), which reflect stroke severity, were situated within our IBZ estimate. The IBZ was most severely injured in case of a territorial infarction. Then, our results are in favour of an increased IBZ vulnerability to ischemia. Moreover, our probabilistic estimates of deep, superficial and IBZ regions can help the everyday spatial classification of lesions.

Computed tomography perfusion in detecting malignant middle cerebral artery infarct

Background:

Computed tomography perfusion (CTP) is an emerging modality which produces maps of time-to- peak (TTP), cerebral blood flow (CBF), and cerebral blood volume (CBV), with a computerized automated map of the infarct and penumbra. This modality provides a better evaluation of the extent of infarction, making it a potential method for assessing patients suffering from large middle cerebral artery (MCA) infarctions.

Methods:

A prospective cohort study of all patients in Hospital Kuala Lumpur, Malaysia, who presented with the clinical diagnosis of a large MCA infarction within 48 h of onset were subjected to CT brain, and CTP scans on admission and were followed up to determine the development of malignant infarction requiring surgical decompression.

Results:

CTP parameters were generally lower in patients with malignant brain infarct (MBI) group compared to the nonMBI group. The largest mean difference between the group was noted in the TTP values (P = 0.005). CTP parameters had a comparable positive predictive value (83%–90%) and high net present value (88–93). CBF with cutoff value of >32.85 of the hemisphere could accurately predict malignant infarctions in 81.4% of cases. The National Institutes of Health Stroke Scale score of more than 13.5 was also found to be able to accurately determine malignant infarct (97.6%). Functional outcome of patients based on Glasgow outcome scale was similar on discharge, however, showed improvement at 6 months during reviewed base on modified Rankin scale (P < 0.001).

Conclusion:

CTP parameters should be included in the initial evaluation of patients to predict malignant brain infarction and facilitate surgical treatment of large MCA infarctions.

Key messages:

CT perfusion parameters have an important role in predicting malignant brain infarction and should be included in the initial evaluation of patients to facilitate the early identification and surgical treatment of large middle cerebral artery infarctions, to improve patient’s prognosis.

Rich-Club Organization: An Important Determinant of Functional Outcome After Acute Ischemic Stroke

Objective: To determine whether the rich-club organization, essential for information transport in the human connectome, is an important biomarker of functional outcome after acute ischemic stroke (AIS). Methods: Consecutive AIS patients (N = 344) with acute brain magnetic resonance imaging (MRI) (<48 h) were eligible for this study. Each patient underwent a clinical MRI protocol, which included diffusion weighted imaging (DWI). All DWIs were registered to a template on which rich-club regions have been defined. Using manual outlines of stroke lesions, we automatically counted the number of affected rich-club regions and assessed its effect on the National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS; obtained at 90 days post-stroke) scores through ordinal regression. Results: Of 344 patients (median age 65, inter-quartile range 54-76 years) with a median DWI lesion volume (DWIv) of 3cc, 64% were male. We established that an increase in number of rich-club regions affected by a stroke increases the odds of poor stroke outcome, measured by NIHSS (OR: 1.77, 95%CI 1.41-2.21) and mRS (OR: 1.38, 95%CI 1.11-1.73). Additionally, we demonstrated that the OR exceeds traditional markers, such as DWIv (OR_NIHSS 1.08, 95%CI 1.06-1.11; OR_mRS 1.05, 95%CI 1.03-1.07) and age (OR_NIHSS 1.03, 95%CI 1.01-1.05; OR_mRS 1.05, 95%CI 1.03-1.07). Conclusion: In this proof-of-concept study, the number of rich-club nodes affected by a stroke lesion presents a translational biomarker of stroke outcome, which can be readily assessed using standard clinical AIS imaging protocols and considered in functional outcome prediction models beyond traditional factors.

Stroke Mechanisms in Symptomatic Intracranial Atherosclerotic Disease: Classification and Clinical Implications

Background and Purpose- In patients with symptomatic intracranial atherosclerotic stenosis, identifying the underlying stroke mechanisms may inform secondary prevention. We aimed to propose reproducible classification criteria for stroke mechanisms based on routine neuroimaging in symptomatic intracranial atherosclerotic stenosis and explore their clinical implications. Methods- We recruited patients with acute ischemic stroke attributed to 50% to 99% intracranial atherosclerotic stenosis in anterior circulation from 2 centers. Two investigators independently classified probable stroke mechanisms as parent artery atherosclerosis occluding penetrating artery, artery-to-artery embolism, hypoperfusion, and mixed mechanisms, with prespecified criteria based on infarct topography and magnetic resonance/computed tomography angiography. These stroke mechanisms were correlated with features of the patients at baseline and recurrent ischemic stroke in the same territory or relevant transient ischemic attack within 1 year. Results- Among 153 patients recruited, the most common stroke mechanisms were isolated hypoperfusion (35.3%) and mixed mechanism of artery-to-artery embolism and hypoperfusion (37.3%) that was associated with higher incidence of dyslipidemia (P=0.045) and hypertension (P=0.033) than patients with other stroke mechanisms. The proposed criteria showed substantial to excellent intrarater and interrater reproducibilities (κ, 0.791-0.908). Overall, 31 patients received interventional treatment of the diseased intracranial artery; 122 received medical treatment, among whom a mixed mechanism of artery-to-artery embolism and hypoperfusion at baseline was associated with higher risk of ischemic stroke in the same territory within 1 year (24.4% versus 7.8%; hazard ratio, 3.40; 95% CI, 1.25-9.20; log-rank P=0.010) than other mechanisms combined. Conclusions- Artery-to-artery embolism and hypoperfusion commonly coexist in ischemic stroke attributed to intracranial atherosclerotic stenosis, which may be associated with higher risk of stroke relapse.

Predictors of Poor Outcome in Patients with Minor Ischemic Stroke by Using Magnetic Resonance Imaging

Although the symptoms of minor ischemic stroke are mild, poor prognosis may occur if left untreated. Therefore, it is particularly important to identify the predictors that associated with poor outcome in patients presenting minor ischemic stroke. The aim of this study was to elucidate the predictors of progression by using magnetic resonance imaging (MRI). A total of 516 patients diagnosed with minor ischemic stroke were enrolled in this study. They were divided into two groups, the progressive group and non-progressive group, according to the modified Rankin Scale (mRS) with the cutoff value of 2 points on day 90 after the stroke onset. We compared the results of MRI scan between the two groups to investigate the potential independent determinants of progression using multivariate logistic regression analysis. Ninety of 516 patients (17.44%) underwent progression. There were 9 factors that were independently associated with poor outcome, including age (OR = 1.045, 95% CI 1.017-1.074), heart disease (OR = 2.021, 95% CI 1.063-3.841), baseline NIHSS score (OR = 1.662, 95% CI 1.177-2.347), limb motor disturbance (OR = 2.430, 95% CI 1.010-5.850), ataxia (OR = 2.929, 95% CI 1.188-7.221), early neurological deterioration (OR = 50.994, 95% CI 17.659-147.258), diameter of infarction (OR = 1.279, 95% CI 1.075-1.521), non-responsible vessel size (OR = 2.518, 95% CI 1.145-5.536), and large-artery atherosclerosis (OR = 2.010, 95% CI 1.009-4.003). This study indicated that age, heart disease, motor disturbance of limb, ataxia, early neurological deterioration, diameter of infarction, size of non-responsible vessels, and large-artery atherosclerosis can be used to assess the prognosis of patients with minor ischemic stroke.

A Novel Neuroimaging Model to Predict Early Neurological Deterioration After Acute Ischemic Stroke

Objective:

In acute ischemic stroke, early neurological deterioration (END) may occur in up to one-third of patients. However, there is still no satisfying or comprehensive predictive model for all the stroke subtypes. We propose a practical model to predict END using magnetic resonance imaging (MRI).

Method:

Patients with anterior circulation infarct were recruited and they underwent an MRI within 24 hours of stroke onset. END was defined as an elevation of ≥2 points on the National Institute of Health Stroke Scale (NIHSS) within 72 hours of stroke onset. We examined the relationships of END to individual END models, including: A, infarct swelling; B, small subcortical infarct; C, mis-match; and D, recurrence.

Results:

There were 163 patients recruited and 43 (26.4%) of them had END. The END models A, B and C significantly predicted END respectively after adjusting for confounding factors (p=0.022, p=0.007 and p<0.001 respectively). In END model D, we examined all imaging predictors of Recur-rence Risk Estimator (RRE) individually and only the “multiple acute infarcts” pattern was signifi-cantly associated with END (p=0.032). When applying END models A, B, C and D, they success-fully predicted END (p<0.001; odds ratio: 17.5[95% confidence interval: 5.1–60.8]), with 93.0% sensitivity, 60.0% specificity, 45.5% positive predictive value and 96.0% negative predictive value.

Conclusion:

The results demonstrate that the proposed model could predict END in all stroke sub-types of anterior circulation infarction. It provides a practical model for clinical physicians to select high-risk patients for more aggressive treatment to prevent END.

Does all single infarction have lower risk of stroke recurrence than multiple infarctions in minor stroke?

BACKGROUND

Single acute infarction (SAI) usually had lower risk of stroke recurrence than multiple acute infarctions (MAIs) in minor stroke. To evaluate whether all SAI had lower risk of stroke recurrence than MAIs in minor stroke.

METHODS

We derived data from the imaging subgroup of the Clopidogrel in High-risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial. Minor stroke were categorized into SAI and MAIs by infarction numbers in diffusion weighted imaging. SAI were classified as lacunar infarction and non-lacunar infarction. The outcome was stroke recurrence within one-year follow-up. We assessed the associations between infarction patterns and stroke recurrence using multivariable Cox regression models.

RESULTS

Overall, 834 patients with minor stroke were included in this subgroup, 553 SAI (381 lacunar infarction, 172 non-lacunar infarction) and 281 MAIs. The rate of stroke recurrence was 7.6%, 15.1% and 15.3% in lacunar infarction of SAI, non-lacunar infarction of SAI and MAIs at one year, respectively. Compared with MAIs, lacunar infarction of SAI had lower risk of stroke recurrence (hazard ratio [HR] 0.41, 95% confidence interval [CI] 0.21-0.80, P = 0.009), but not in non-lacunar infarction of SAI (HR 1.01, 95% CI 0.60-1.69, P = 0.98).

CONCLUSIONS

Lacunar infarction of SAI have lower risk of stroke recurrence than MAIs, while non-lacunar infarction of SAI might have similar risk as MAIs. Except for the number of infarctions, size and location should also be considered to stratify risk of stroke recurrence in minor stroke.

TRIAL REGISTRATION

http://www.clinicaltrials.gov Unique identifier: NCT00979589 . Date of registration: September 2009.

Hemodynamic Markers in the Anterior Circulation as Predictors of Recurrent Stroke in Patients With Intracranial Stenosis

Background and Purpose- Although aggressive medical therapy was superior to stenting in the SAMMPRIS trial (Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis), the stroke rate in the medical arm was still high. The aim of this study was to determine the association between hemodynamic markers (borderzone infarct pattern and impaired collateral flow on baseline imaging) and rates of recurrent stroke in patients treated medically in SAMMPRIS. Methods- This was a post hoc analysis of patients whose qualifying event for SAMMPRIS was an infarct in the territory of a stenotic middle cerebral artery or intracranial carotid artery. Infarcts were adjudicated as involving primarily internal or cortical borderzone territories, the core middle cerebral artery territory, or perforator territories, and collateral flow was assessed according to a standard scale (American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology). Log-rank tests and χ2 tests were performed to assess associations of infarct patterns and collateral flow with rates of recurrent stroke. Results- Of 101 patients who qualified, 14 of 53 (26.4%) with borderzone infarcts, 2 of 24 (8.3%) with core middle cerebral artery infarcts, and 3 of 24 (12.5%) with perforator infarcts had a recurrent stroke in the territory (P=0.14 for comparing the 3 groups, P=0.052 for borderzone versus nonborderzone). Of 82 patients with collateral flow assessment, 30 of 43 (70%) with borderzone infarcts, 7 of 19 (37%) with core middle cerebral artery infarcts, and 11 of 20 (55%) with perforator infarcts had impaired collateral flow distal to the stenosis (P=0.049). Patients with borderzone infarcts and impaired collateral flow had the highest risk of recurrent stroke (37%). Conclusions- Borderzone infarcts and impaired collateral flow identify a subgroup of patients with intracranial stenosis who are at particularly high risk of recurrent stroke on medical treatment. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT00576693.

Clinical and radiological factors associated with unfavorable outcome after intravenous thrombolysis in patients with mild ischemic stroke

BACKGROUND

A significant proportion of patients with mild ischemic stroke become disabled despite receiving intravenous thrombolytic therapy. The purpose of this study was to assess the clinical and radiological factors associated with unfavorable outcomes in patients with minor ischemic stroke that received intravenous recombinant tissue plasminogen activator (rt-PA) therapy.

METHODS

We identified anterior circulation stroke patients with initial National Institutes of Health Stroke Scale (NIHSS) scores ≤5 who received intravenous thrombolysis within 4.5 h of stroke onset and had pretreatment magnetic resonance (MR)/MR angiography using our prospective stroke database. We analyzed baseline characteristics, infarction patterns on diffusion-weighted imaging (DWI), and steno-occlusive lesions on MR angiography. Unfavorable outcome was defined as a modified Rankin Scale (mRS) score ≥ 2 at 90 days. Logistic regression was used to determine independent predictors of unfavorable outcomes.

RESULTS

Among 121 patients (85 men; mean age, 63.4 ± 11.3 years) included in this study, 46 (38%) had unfavorable outcomes at 90 days and DWI lesion patterns showing infarction in the deep middle cerebral artery (MCA) territory involving the perforating artery area was observed in 47 (38.8%) patients. On multivariable analysis, unfavorable outcomes at 90 days were associated with diabetes [odds ratio (OR), 3.41; 95% confidence interval (CI), 1.06-10.9; P = 0.039), NIHSS score on admission (OR, 2.11; 95% CI, 1.35-3.30; P = 0.001), and infarction in the deep MCA territory on DWI (OR, 4.19; 95% CI, 1.63-10.8; P = 0.003). Lesions in the deep MCA territory was independently associated with early neurological deterioration (P = 0.032). The patients without deep MCA territory infarction had a higher prevalence of cardiac embolism (P = 0.009).

CONCLUSIONS

Higher NIHSS scores, diabetes, and deep MCA territory infarction may be useful for predicting unfavorable outcomes in patients with minor stroke treated with intravenous rt-PA therapy.

Optimizing the Definitions of Stroke, Transient Ischemic Attack, and Infarction for Research and Application in Clinical Practice

BACKGROUND AND PURPOSE

Until now, stroke and transient ischemic attack (TIA) have been clinically based terms which describe the presence and duration of characteristic neurological deficits attributable to intrinsic disorders of particular arteries supplying the brain, retina, or (sometimes) the spinal cord. Further, infarction has been pathologically defined as death of neural tissue due to reduced blood supply. Recently, it has been proposed we shift to definitions of stroke and TIA determined by neuroimaging results alone and that neuroimaging findings be equated with infarction.

METHODS

We examined the scientific validity and clinical implications of these proposals using the existing published literature and our own experience in research and clinical practice.

RESULTS

We found that the proposals to change to imaging-dominant definitions, as published, are ambiguous and inconsistent. Therefore, they cannot provide the standardization required in research or its application in clinical practice. Further, we found that the proposals are scientifically incorrect because neuroimaging findings do not always correlate with the clinical status or the presence of infarction. In addition, we found that attempts to use the proposals are disrupting research, are otherwise clinically unhelpful and do not solve the problems they were proposed to solve.

CONCLUSION

We advise that the proposals must not be accepted. In particular, we explain why the clinical focus of the definitions of stroke and TIA should be retained with continued sub-classification of these syndromes depending neuroimaging results (with or without other information) and that infarction should remain a pathological term. We outline ways the established clinically based definitions of stroke and TIA, and use of them, may be improved to encourage better patient outcomes in the modern era.

Stroke Caused by Atherosclerosis of the Major Intracranial Arteries

Our goal in this review is to discuss the pathophysiology, diagnosis, and treatment of stroke caused by atherosclerosis of the major intracranial arteries. References for the review were identified by searching PubMed for related studies published from 1955 to June 2016 using search terms intracranial stenosis and intracranial atherosclerosis. Reference sections of published randomized clinical trials and previously published reviews were searched for additional references. Intracranial atherosclerotic disease is a highly prevalent cause of stroke that is associated with a high risk of recurrent stroke. It is more prevalent among blacks, Hispanics, and Asians compared with whites. Diabetes mellitus, hypertension, metabolic syndrome, smoking, hyperlipidemia, and a sedentary lifestyle are the major modifiable risk factors associated with intracranial atherosclerotic disease. Randomized clinical trials comparing aggressive management (dual antiplatelet treatment for 90 days followed by aspirin monotherapy and intensive management of vascular risk factors) with intracranial stenting plus aggressive medical management have shown medical management alone to be safer and more effective for preventing stroke. As such, aggressive medical management has become the standard of care for symptomatic patients with intracranial atherosclerotic disease. Nevertheless, there are subgroups of patients who are still at high risk of stroke despite being treated with aggressive medical management. Future research should aim to establish clinical, serological, and imaging biomarkers to identify high-risk patients, and clinical trials evaluating novel therapies should be focused on these patients.

Lenticulostriate Artery Involvement is Predictive of Poor Outcomes in Superficial Middle Cerebral Artery Territory Infarction

PURPOSE

Patients with superficial middle cerebral artery (MCA) territory infarction may have concomitant lenticulostriate artery (LSA) territory infarction. We investigated the mechanisms thereof and the outcomes of patients with superficial MCA territory infarction according to the presence or absence of LSA involvement.

MATERIALS AND METHODS

Consecutive patients with first-ever infarction in the unilateral superficial MCA territory were included in this study. They were divided into the superficial MCA only (SM) group and the superficial MCA plus LSA (SM+L) group.

RESULTS

Of the 398 patients, 84 patients (21.1%) had LSA involvement (SM+L group). The SM+L group more frequently had significant stenosis of the proximal MCA or carotid artery and high-risk cardioembolic sources. Stroke severity and outcomes were remarkably different between the groups. The SM+L group showed more severe neurologic deficits (National Institute of Health Stroke Scale score 10.8±7.1 vs. 4.0±5.0, p<0.001) and larger infarct in the superficial MCA territory (40.8±62.6 cm³ vs. 10.8±21.8 cm³, p<0.001) than the SM group. A poor functional outcome (mRS >2) at 3 months was more common in the SM+L group (64.3% vs. 15.9%, p<0.001). During a mean follow-up of 26 months, 67 patients died. All-cause (hazard ratio, 2.246) and stroke (hazard ratio, 9.193) mortalities were higher in the SM+L group than the SM group. In multivariate analyses, LSA involvement was an independent predictor of poor functional outcomes and stroke mortality.

CONCLUSION

LSA territory involvement is predictive of poor long-term outcomes in patients with superficial MCA territory infarction.

Collateral Assessment by CT Angiography as a Predictor of Outcome in Symptomatic Cervical Internal Carotid Artery Occlusion

BACKGROUND AND PURPOSE

Cervical internal carotid artery occlusion can present with varied clinical manifestations such as transient ischemic attack, stroke, and chronic ocular ischemia, or can be asymptomatic. The outcome in these patients is considerably influenced by cerebral hemodynamic compensatory adaptation of the intracranial collateral pathways. Our aim was to study whether collateral circulation as assessed by CT angiography can predict 3-month outcome and initial stroke severity in patients with symptomatic cervical ICA occlusion.

MATERIALS AND METHODS

This was a retrospective study of 65 patients with symptomatic cervical ICA occlusion from January 2011 to December 2013. The collateral vessels (anterior and posterior communicating arteries, ophthalmic artery, and leptomeningeal arteries) were assessed by CTA. The outcome at 3 months was defined as poor if the modified Rankin Scale score was ≥3.

RESULTS

The mean age of subjects was 57 ± 11.6 years (range, 32-80 years), and 92% were men. Thirty-three (50.8%) patients had poor outcome. Absence of the ipsilateral ophthalmic artery, poor leptomeningeal collaterals, and <2 collaterals were predictors of stroke severity at onset and poor 3-month outcome in univariate analysis. In the multiple logistic regression analysis, inadequate flow through the secondary collaterals (ipsilateral ophthalmic artery or leptomeningeal collaterals; OR, 4.5; 95% CI, 1.4-14.9; P = .01) and higher NIHSS score at stroke onset (OR, 19.2; 95% CI, 2.2-166.2; P = .007) independently predicted poor outcome at 3 months.

CONCLUSIONS

Assessment of collateral circulation with CTA can be a useful predictor of 3-month outcome in patients with symptomatic cervical ICA occlusion.

Lesions on DWI and the Outcome in Hyperacute Posterior Circulation Stroke

BACKGROUND

few studies have addressed the association between the characteristics of ischemic lesions detected by diffusion-weighted imaging (dWi) and the clinical outcome in patients with hyperacute posterior circulation ischemic stroke. this study demonstrates a relationship between the findings assessed by dWi and the outcome in patients with hyperacute posterior circulation ischemic stroke.

METHODS

We reviewed data from 118 patients who had posterior circulation ischemic stroke within six hours from the onset of their symptoms. the clinical outcome included early neurological deterioration (end) and a favorable outcome at three months after the onset of symptoms. using dWi, the lesion volume and the number and location of injured anatomical regions were analyzed to evaluate whether the results correlated with the clinical outcome measures.

RESULTS

the number of injured anatomical regions assessed by dWi was associated with the initial and delayed neurological status. Both the total volume and the number of injured anatomical regions associated with end and a favorable outcome. analysis of the location of the injured regions determined that only a pontine lesion independently associated with end. interestingly, four out of five patients who underwent decompressive craniectomy exhibited a large infarction volume but minor symptoms.

CONCLUSIONS

in patients with hyperacute posterior circulation ischemic strokes, the lesions assessed by dWi were associated with the clinical outcome, regardless of the initial neurological status. dWi is an effective initial imaging tool for assessing the extent of lesions and clinical outcomes in patients with hyperacute posterior circulation ischemic stroke.

Early Magnetic Resonance Imaging Predicts Early Neurological Deterioration in Acute Middle Cerebral Artery Minor Stroke

BACKGROUND

Early neurological deterioration (END) is an important factor associated with worse clinical outcome in minor strokes. Early magnetic resonance imaging (MRI) findings can provide better sensitivity to delineate stroke pathophysiology and have diagnostic value associated with causative mechanisms. The aim of this study was to investigate the relationship between early MRI finding and the presence of END in minor stroke patients with lesions in the middle cerebral artery (MCA) territory.

METHODS

Consecutive MCA minor stroke patients who were admitted to our center within 24 hours of symptom onset were included in this study. All patients underwent MRI within 24 hours of admission. We analyzed baseline characteristics, infarction patterns, and treatment algorithms. The correlation between early MRI findings and END, defined as National Institutes of Health Stroke Scale score increasing more than 2 points during 72 hours after admission, was also determined.

RESULTS

Across 211 patients meeting entry criteria between January 2010 and December 2013, internal border-zone (IBZ) infarcts on early MRI scan were observed in 23 of 65 patients with END (35.4%) and in 18 of 146 patients without END (12.3%, P < .001). Patients with IBZ infarcts were found to have more hyperlipidemia, less perforating artery infarcts, more pial artery infarcts, more cortical border-zone infarcts and more ipsilateral large arterial stenosis. Logistic regression analysis revealed that IBZ infarct was independently associated with END after adjustment for other factors (odds ratio, 2.50; 95% confidence interval, 1.09-5.74; P = .031).

CONCLUSIONS

Early MRI patterns of IBZ infarction are associated with END in minor stroke patients with acute infarcts of the MCA territory.

Recovery Potential After Acute Stroke

In acute stroke, the major factor for recovery is the early use of thrombolysis aimed at arterial recanalization and reperfusion of ischemic brain tissue. Subsequently, neurorehabilitative training critically improves clinical recovery due to augmention of postlesional plasticity. Neuroimaging and electrophysiology studies have revealed that the location and volume of the stroke lesion, the affection of nerve fiber tracts, as well as functional and structural changes in the perilesional tissue and in large-scale bihemispheric networks are relevant biomarkers of post-stroke recovery. However, associated disorders, such as mood disorders, epilepsy, and neurodegenerative diseases, may induce secondary cerebral changes or aggravate the functional deficits and, thereby, compromise the potential for recovery.

DWI Lesion Patterns Predict Outcome in Stroke Patients with Thrombolysis

BACKGROUND

Lesion patterns may predict prognosis after acute ischemic stroke within the middle cerebral artery (MCA) territory; yet it remains unclear whether such imaging prognostic factors are related to patient outcome after intravenous thrombolysis.

AIMS

The aim of this study is to investigate the clinical outcome after intravenous thrombolysis in acute MCA ischemic strokes with respect to diffusion-weighted imaging (DWI) lesion patterns.

METHODS

Consecutive acute ischemic stroke cases of the MCA territory treated over a 7-year period were retrospectively analyzed. All acute MCA stroke patients underwent a MRI scan before intravenous thrombolytic therapy was included. DWI lesions were divided into 6 patterns (territorial, other cortical, small superficial, internal border zone, small deep, and other deep infarcts). Lesion volumes were measured by dedicated imaging processing software. Favorable outcome was defined as modified Rankin scale (mRS) of 0-2 at 90 days.

RESULTS

Among the 172 patients included in our study, 75 (43.6%) were observed to have territorial infarct patterns or other deep infarct patterns. These patients also had higher baseline NIHSS score (p < 0.001), a higher proportion of large cerebral artery occlusions (p < 0.001) and larger infarct volume (p < 0.001). Favorable outcome (mRS 0-2) was achieved in 89 patients (51.7%). After multivariable analysis, groups with specific lesion patterns, including territorial infarct and other deep infarct pattern, were independently associated with favorable outcome (OR 0.40; 95% CI 0.16-0.99; p = 0.047).

CONCLUSIONS

Specific lesion patterns predict differential outcome after intravenous thrombolysis therapy in acute MCA stroke patients.

Multidetector computed tomography angiography in clinically suspected hyperacute ischemic stroke in the anterior circulation: an etiological workup in a cohort of Brazilian patients

OBJECTIVE

The potential of computed tomography angiography (CTA) was assessed for early determination of stroke subtypes in a Brazilian cohort of patients with stroke.

METHOD

From July 2011 to July 2013, we selected patients with suspected hyperacute stroke (< 6 hours). Intracranial and cervical arteries were scrutinized on CTA and their imaging features were correlated with concurrent subtype of stroke.

RESULTS

Stroke was documented in 50/106 selected patients (47.2%) based on both clinical grounds and imaging follow-up (stroke group), with statistically significant arterial stenosis and vulnerable plaques on CTA. Intracranial large artery disease was demonstrated in 34% of patients in the stroke group. Partial territorial infarct prevailed (86%) while artery-to-artery embolization was the most common stroke mechanism (52%).

CONCLUSION

Multidetector CTA was useful for the etiologic work-up of hyperacute ischemic stroke and facilitated the knowledge about the topographic pattern of brain infarct in accordance with its causative mechanism.

Mitochondrial DNA haplogroups and short-term neurological outcomes of ischemic stroke

Stroke is one of the leading causes of death and long-term disability worldwide. Mitochondrial DNA (mtDNA) is a potential contributor for the sex differences of ischemic stroke heritability. Although mtDNA haplogroups were associated with stroke onset, their impacts on stroke outcomes remain unclear. This study aimed to evaluate the impacts of mtDNA haplogroups on short-term outcomes of neurological functions in patients with ischemic stroke. A total of 303 patients were included, and their clinical data and mtDNA sequences were analyzed. Based on the changes between baseline and 14-day follow-up stroke severity, our results showed that haplogroup N9 was an independent protective factor against neurological worsening in acute ischemic stroke patients. These findings supported that mtDNA variants play a role in post-stroke neurological recovery, thus providing evidences for future pharmacological intervention in mitochondrial function.

Data science of stroke imaging and enlightenment of the penumbra

Imaging protocols of acute ischemic stroke continue to hold significant uncertainties regarding patient selection for reperfusion therapy with thrombolysis and mechanical thrombectomy. Given that patient inclusion criteria can easily introduce biases that may be unaccounted for, the reproducibility and reliability of the patient screening method is of utmost importance in clinical trial design. The optimal imaging screening protocol for selection in targeted populations remains uncertain. Acute neuroimaging provides a snapshot in time of the brain parenchyma and vasculature. By identifying the at-risk but still viable penumbral tissue, imaging can help estimate the potential benefit of a reperfusion therapy in these patients. This paper provides a perspective about the assessment of the penumbral tissue in the context of acute stroke and reviews several neuroimaging models that have recently been developed to assess the penumbra in a more reliable fashion. The complexity and variability of imaging features and techniques used in stroke will ultimately require advanced data driven software tools to provide quantitative measures of risk/benefit of recanalization therapy and help aid in making the most favorable clinical decisions.

Sensitivity of diffusion- and perfusion-weighted imaging for diagnosing acute ischemic stroke is 97.5%

BACKGROUND AND PURPOSE

MRI using diffusion-weighted imaging (DWI) is the most sensitive diagnostic imaging modality for early detection of ischemia, but how accurate is it and how much does perfusion-weighted imaging (PWI) add to the sensitivity have to be known.

METHODS

In this single-center study, we collected epidemiological, imaging, and outcome data on all patients with stroke undergoing MRI-based treatment with intravenous tissue-type plasminogen activator at our center from 2004 to 2010. The DWI negative patients were identified, and we calculated the sensitivity and specificity of DWI and additional PWI for diagnosing acute ischemic stroke. We compared DWI positive and negative patients to identify characteristics associated with DWI negativity.

RESULTS

Five hundred sixty-nine consecutive patients were treated with intravenous tissue-type plasminogen activator on the basis of an acute MRI. A DWI lesion was evident in 518 patients. Forty-seven patients were DWI negative; however, a relevant PWI lesion was found in 33 of these patients. Four stroke mimics were treated with intravenous tissue-type plasminogen activator and 1 of these patients had a DWI lesion. Thus, 8% of all patients with stroke were DWI negative. The combination of DWI and PWI resulted in a sensitivity of 97.5% for the ischemic stroke diagnosis. DWI negativity was associated with less severe strokes, location in the posterior circulation, a longer time from onset to scan, and an improved 90-day outcome. The cause of small-vessel disease was more likely to be DWI negative.

CONCLUSIONS

The combination of DWI and PWI before intravenous tissue-type plasminogen activator confirms the diagnosis in 97.5% of all ischemic strokes.

Infarct patterns, collaterals and likely causative mechanisms of stroke in symptomatic intracranial atherosclerosis

BACKGROUND

There are limited data on the specific mechanisms of stroke in patients with intracranial atherosclerotic stenosis (ICAS). We undertook this study to describe infarct patterns and likely mechanisms of stroke in a large cohort of patients with ICAS, and to evaluate the relationship of these infarct patterns to angiographic features (collaterals, stenosis location and stenosis severity).

METHODS

We evaluated infarct patterns in the territory of a stenotic intracranial artery on neuroimaging performed at baseline and during follow-up if a recurrent stroke occurred in patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial. We defined the likely mechanism of stroke (artery-to-artery embolism, perforator occlusion, hypoperfusion or mixed) according to the site of ICAS and based on the infarct patterns on neuroimaging. Collaterals were assessed using American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) grades, and stenosis severity using the WASID trial's measurement technique. We evaluated the association of infarct patterns with angiographic features using χ(2) tests.

RESULTS

The likely mechanisms of stroke based on the infarct patterns at baseline in the 136 patients included in the study were artery-to-artery embolism (n = 69; 50.7%), perforator occlusion (n = 34; 25%), hypoperfusion (n = 12; 8.8%) and mixed (n = 21; 15.5%). Perforator-occlusive infarcts were more frequent in the posterior circulation, and mixed patterns were more prevalent in the anterior circulation (both p < 0.01). Most of the mixed patterns in the anterior circulation combined small pial or scattered multiple cortical infarcts with infarcts in border-zone regions, especially the cortical ones. Isolated border-zone infarcts were not significantly associated with a poor grading for collaterals or the severity of stenosis. Among 47 patients with a recurrent infarct during follow-up, the infarct patterns suggested an artery-to-artery embolic mechanism in 29 (61.7%).

CONCLUSIONS

Artery-to-artery embolism is probably the most common mechanism of stroke in both the anterior and the posterior circulations in patients with ICAS. An extension of intracranial atherosclerosis at the site of stenosis into adjacent perforators also appears to be a common mechanism of stroke, particularly in the posterior circulation, whereas hypoperfusion as the sole mechanism is relatively uncommon. Further research is important to accurately establish the specific mechanisms of stroke in patients with ICAS, since preliminary data suggest that the underlying mechanism of stroke is an important determinant of prognosis.

[Multimodal imaging protocols and their predictive role in acute stroke functional outcome]

Brain imaging plays a central role in the assessment of patients with acute ischemic stroke. Within a few minutes, modern multimodal imaging protocols can provide one with comprehensive information about prognosis, management, and outcome of the disease, and may detect changes in the intracranial structures reflecting severity of the ischemic injury depicted by four Ps: parenchyma (of the brain), pipes (i.e., the cerebral blood vessels), penumbra, and permeability (of the blood brain barrier). In this article, we have reviewed neuroradiological predictors of stroke functional outcome in the light of the aforementioned four Ps.

Imaging and clinical predictors of unfavorable outcome in medically treated symptomatic intracranial atherosclerotic disease

BACKGROUND

Patients with symptomatic intracranial atherosclerotic disease (sICAD) have an increased risk of stroke and vascular death. The aim of the study was to evaluate the natural history and outcome of patients with sICAD treated medically.

METHODS

The study population was first-ever transient ischemic attack (TIA) or stroke patients presenting to our institute who on vascular imaging had isolated intracranial atherosclerosis as cause of their symptoms and have a follow-up of 90 days. Unfavorable outcome was defined as occurrence of TIA, stroke, acute coronary event, and/or vascular death.

RESULTS

Fifty-three (11.8%) of the 449 ischemic stroke patients had sICAD. The risk of stroke in sICAD was 8.9%, 11.1%, 13.3%, and 15.6% in first 7 days, 30 days, 90 days, and 1 year, respectively. Five (11.1%) had cardiovascular events and accounted for 50% of mortality. The predictors of unfavorable outcome were presented as limb weakness (85.7% versus 58.8%, hazard ratio 1.5; 95% confidence interval [CI], .05-.9; P = .04), National Institutes of Health Stroke Scale (NIHSS) score 8 at admission (50% versus 5.9%, hazard ratio 8.5; 95% CI, .007-.5; P = .02), magnetic resonance imaging (MRI) with multiple diffusion-weighted imaging (DWI) lesions (65.4% versus 26.7%; 95% CI, .04-.7; P = .01), and angiography suggestive of diffuse atherosclerosis (50% versus 11.8%; 95% CI, odds ratio .02-.7; P = .009). On stepwise multiple regression, variables for unfavorable outcome were NIHSS score of 8 or more at admission (P = .001), multiple DWI lesion on MRI (P = .04), and diffuse atherosclerosis on angiography (P = .006).

CONCLUSION

The patients with sICAD have a high risk of stroke and cardiac events even on aggressive medical treatment. Clinical and imaging features can identify this high-risk group.

Effect of statin on progression of symptomatic intracranial atherosclerosis

BACKGROUND

Symptomatic intracranial atherosclerosis (ICAS) is a dynamic disease that frequently progresses. Statins have been shown to have anti-atherosclerotic activity. We therefore investigated whether statins could prevent progression of ICAS.

METHODS

This retrospective cohort study assessed 55 patients with acute ischemic stroke and symptomatic ICAS in the middle cerebral or basilar arteries as shown on magnetic resonance angiography (MRA), with follow-up MRA performed more than 1 year after the index stroke. Change in ICAS was classified as progressive, regressive, or stable. Baseline clinical characteristics and risk factor control during follow-up were assessed, and laboratory tests were performed at the time of follow-up MRA. The statin group was defined as patients regularly treated with statins for more than 75% of the follow-up period; the remaining patients were defined as the non-statin group.

RESULTS

At a median follow-up time of 21.8 months (range, 11.8-66.1 months), the statin group consisted of 26 (47.3%) patients and the non-statin group of 29 (52.7%). During follow-up, 6 (10.9%) patients progressed, 14 (25.5%) regressed, and 35 (63.6%) remained stable. Statin treatment was significantly associated with non-progression of ICAS (p=0.024). Two patients in the non-statin group had recurrent strokes. Border-zone infarcts were associated with progression of ICAS (3/6, 50%; p=0.007), whereas risk factors and inflammatory biomarkers were not related to progression.

CONCLUSIONS

Treatment with statins may prevent progression of symptomatic ICAS. Prospective randomized controlled trials are required to confirm that statins protect against such progression.

The role of MRI as a prognostic tool in ischemic stroke

Magnetic resonance imaging (MRI) is an invaluable tool used in the diagnosis of ischemic stroke. Ongoing technological advances in MRI technology and advent of new imaging sequences has now made it possible to use MRI as a prognostic tool both in the acute and chronic stages of cerebral ischemia. This review summarizes the role of MRI in estimating final tissue outcome, specifically by providing information on severity and location of ischemic insult, cerebral blood flow dynamics, vascular status, and cerebral reserve. All of these predictions can then be used to make projections regarding clinical outcome, and can be refined by other prognostic models to estimate recovery and risk of further ischemic events. These algorithms, in the end, can ultimately help the clinician in tailoring therapies on an individual basis and optimize the risk-benefit ratio of therapeutic approaches used in the acute and chronic stages of ischemic stroke. The implementation of such prognostic algorithms to clinical imaging workstations and calculation of all the possible projections within minutes after completion of imaging are likely to become an integral part of clinical practice in the near future.

Identification of modifiable and nonmodifiable risk factors for neurologic deterioration after acute ischemic stroke

BACKGROUND

Neurologic deterioration (ND) after ischemic stroke has been shown to impact short-term functional outcome and is associated with in-hospital mortality.

METHODS

Patients with acute ischemic stroke who presented between July 2008 and December 2010 were identified and excluded for in-hospital stroke, presentation >48 hours since last seen normal, or unknown time of last seen normal. Clinical and laboratory data, National Institutes of Health Stroke Scale (NIHSS) scores, and episodes of ND (increase in NIHSS score ≥ 2 within a 24-hour period) were investigated.

RESULTS

Of the 596 patients screened, 366 were included (median age 65 years; 42.1% female; 65.3% black). Of these, 35.0% experienced ND. Patients with ND were older (69 v 62 years; P < .0001), had more severe strokes (median admission NIHSS score 12 v 5; P < .0001), carotid artery stenosis (27.0% v 16.8%; P = .0275), and coronary artery disease (26.0% v 16.4%; P = .0282) compared to patients without ND. Patients with ND had higher serum glucose on admission than patients without ND (125.5 v 114 mg/dL; P = .0036). After adjusting for crude variables associated with ND, age >65 years, and baseline NIHSS score >14 remained significant independent predictors of ND. In a logistic regression analysis adjusting for age and serum glucose, each 1-point increase in admission NIHSS score was associated with a 7% increase in the odds of ND (odds ratio 1.07; 95% confidence interval 1.04-1.10; P < .0001).

CONCLUSIONS

Older patients and patients with more severe strokes are more likely to experience ND. Initial stroke severity was the only significant, independent, and modifiable risk factor for ND, amenable to recanalization and reperfusion.

Border zone infarcts: pathophysiologic and imaging characteristics

Border zone or watershed infarcts are ischemic lesions that occur in characteristic locations at the junction between two main arterial territories. These lesions constitute approximately 10% of all brain infarcts and are well described in the literature. Their pathophysiology has not yet been fully elucidated, but a commonly accepted hypothesis holds that decreased perfusion in the distal regions of the vascular territories leaves them vulnerable to infarction. Two types of border zone infarcts are recognized: external (cortical) and internal (subcortical). To select the most appropriate methods for managing these infarcts, it is important to understand the underlying causal mechanisms. Internal border zone infarcts are caused mainly by hemodynamic compromise, whereas external border zone infarcts are believed to result from embolism but not always with associated hypoperfusion. Various imaging modalities have been used to determine the presence and extent of hemodynamic compromise or misery perfusion in association with border zone infarcts, and some findings (eg, multiple small internal infarcts) have proved to be independent predictors of subsequent ischemic stroke. A combination of several advanced techniques (eg, diffusion and perfusion magnetic resonance imaging and computed tomography, positron emission tomography, transcranial Doppler ultrasonography) can be useful for identifying the pathophysiologic process, making an early clinical diagnosis, guiding management, and predicting the outcome.

The determinants of stroke phenotypes were different from the predictors (CHADS2 and CHA2DS2-VASc) of stroke in patients with atrial fibrillation: a comprehensive approach

Background

Atrial fibrillation (AF) is a leading cause of fatal ischemic stroke. It was recently reported that international normalized ratio (INR) levels were associated with infarct volumes. However, factors other than INR levels that affect stroke phenotypes are largely unknown. Therefore, we evaluated the determinants of stroke phenotypes (pattern and volume) among patients with AF who were not adequately anticoagulated.

Methods

We analyzed data pertaining to consecutive AF patients admitted over a 6-year period with acute MCA territory infarcts. We divided the patients according to DWI (diffusion-weighted imaging) lesion volumes and patterns, and the relationship between stroke predictors (the CHADS₂ and CHA₂DS₂-VASc score), systemic, and local factors and each stroke phenotype were then evaluated.

Results

The stroke phenotypes varied among 231 patients (admission INR median 1.06, interquartile range (IQR) 1.00-1.14). Specifically, (1) the DWI lesion volumes ranged from 0.04-338.62 ml (median 11.86 ml; IQR, 3.07-44.20 ml) and (2) 46 patients had a territorial infarct pattern, 118 had a lobar/deep pattern and 67 had a small scattered pattern. Multivariate testing revealed that the CHADS₂ and CHA₂DS₂-VASc score were not related to either stroke phenotype. Additionally, the prior use of antiplatelet agents was not related to the stroke phenotypes. Congestive heart failure and diastolic dysfunction were not associated with stroke phenotypes.

Conclusions

The results of this study indicated that the determinants of stroke phenotypes were different from the predictors (i.e., CHADS2 and CHA₂DS₂-VASc score) of stroke in patients with AF.

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.

Ischemic stroke and cancer: stroke severely impacts cancer patients, while cancer increases the number of strokes

Background

Cancer and ischemic stroke are two of the most common causes of death among the elderly, and associations between them have been reported. However, the main pathomechanisms of stroke in cancer patients are not well known, and can only be established based on accurate knowledge of the characteristics of cancer-related strokes. We review herein recent studies concerning the clinical, laboratory, and radiological features of patients with cancer-related stroke.

Main Contents

This review covers the epidemiology, underlying mechanisms, and acute and preventive treatments for cancer-related stroke. First, the characteristics of stroke (clinical and radiological features) and systemic cancer (type and extent) in patients with cancer-specific stroke are discussed. Second, the role of laboratory tests in the early identification of patients with cancer-specific stroke is discussed. Specifically, serum D-dimer levels (as a marker of a hypercoagulable state) and embolic signals on transcranial Doppler (suggestive of embolic origin) may provide clues regarding changes in the levels of coagulopathy related to cancer and anticoagulation. Finally, strategies for stroke treatment in cancer patients are discussed, emphasizing the importance of preventive strategies (i.e., the use of anticoagulants) over acute revascularization therapy in cancer-related stroke.

Conclusion

Recent studies have revealed that the characteristics of cancer-related stroke are distinct from those of conventional stroke. Our understanding of the characteristics of cancer-related stroke is essential to the correct management of these patients. The studies presented in this review highlight the importance of a personalized approach in treating stroke patients with cancer.

A score to predict early risk of recurrence after ischemic stroke

BACKGROUND

There is currently no instrument to stratify patients presenting with ischemic stroke according to early risk of recurrent stroke. We sought to develop a comprehensive prognostic score to predict 90-day risk of recurrent stroke.

METHODS

We analyzed data on 1,458 consecutive ischemic stroke patients using a Cox regression model with time to recurrent stroke as the response and clinical and imaging features typically available to physician at admission as covariates. The 90-day risk of recurrent stroke was calculated by summing up the number of independent predictors weighted by their corresponding beta-coefficients. The resultant score was called recurrence risk estimator at 90 days or RRE-90 score (available at: http://www.nmr.mgh.harvard.edu/RRE-90/).

RESULTS

Sixty recurrent strokes (54 had baseline imaging) occurred during the follow-up period. The risk adjusted for time to follow-up was 6.0%. Predictors of recurrence included admission etiologic stroke subtype, prior history of TIA/stroke, and topography, age, and distribution of brain infarcts. The RRE-90 score demonstrated adequate calibration and good discrimination (area under the ROC curve [AUC] = 0.70-0.80), which was maintained when applied to a separate cohort of 433 patients (AUC = 0.70-0.76). The model's performance was also maintained for predicting early (14-day) risk of recurrence (AUC = 0.80).

CONCLUSIONS

The RRE-90 is a Web-based, easy-to-use prognostic score that integrates clinical and imaging information available in the acute setting to quantify early risk of recurrent stroke. The RRE-90 demonstrates good predictive performance, suggesting that, if validated externally, it has promise for use in creating individualized patient management algorithms and improving clinical practice in acute stroke care.