Diffusion-weighted MR imaging in transient ischaemic attacks

Motor impairments in transient ischemic attack increase the odds of a positive diffusion-weighted imaging: A meta-analysis

BACKGROUND

Unilateral motor impairment is a key symptom used in the diagnosis of transient ischemic attack (TIA). Diffusion-weighted imaging (DWI) is a promising diagnostic tool for detecting ischemic lesions. While both motor impairments and DWI abnormalities are linked to the diagnosis of TIA, the association between these prognostic factors is not well understood.

OBJECTIVE

To examine the association between unilateral motor impairments and the odds of a positive DWI in TIA. Further, to determine whether the time between symptom onset and neuroimaging (delay to scan) influences the odds of a positive DWI.

METHODS

We used PRISMA guidelines to conduct a systematic search from 1989 to 2018. We included studies that reported number of individuals with/without unilateral motor symptoms and a positive/negative DWI.

RESULTS

Twenty-four studies from North America, Australia, Asia, and Europe were submitted to a meta-analysis. A pooled odds ratio of 1.80 (95% CI, 1.45-2.24, p = 0.00; I2 = 57.38) suggested that the odds of a positive DWI are greater in TIA individuals who experience motor symptoms as compared with those who experience no motor symptoms. Further, increasing the time delay to scan from the symptom onset (>2 days) did not influence the odds of a positive DWI as compared with an earlier scan (≤2 days).

CONCLUSIONS

The current meta-analysis provides cumulative evidence from 6710 individuals with TIA that the presence of motor symptoms increases the odds of a positive DWI by two-folds. These findings transform the clinical perception into evidence-based knowledge that motor impairments elevate the risk for brain tissue damage. Unilateral motor impairments in a cerebrovascular event should increase a physician's suspicion of detecting brain infarctions. These findings may influence the clinical management of TIA by generating faster response to motor impairments in TIA and accelerating referral to specialized stroke clinic.

Role of Perfusion-Weighted Imaging in a Diffusion-Weighted-Imaging-Negative Transient Ischemic Attack

BACKGROUND AND PURPOSE

The absence of acute ischemic lesions in diffusion-weighted imaging (DWI) in transient ischemic attack (TIA) patients makes it difficult to diagnose the true vascular etiologies. Among patients with DWI-negative TIA, we investigated whether the presence of a perfusion-weighted imaging (PWI) abnormality implied a true vascular event by identifying new acute ischemic lesions in follow-up magnetic resonance imaging (MRI) in areas corresponding to the initial PWI abnormality.

METHODS

The included patients underwent DWI and PWI within 72 hours of TIA and also follow-up DWI at 3 days after the initial MRI. These patients had visited the emergency room between July 2009 and May 2015. Patients who demonstrated initial DWI lesions were excluded. The initial PWI abnormalities in the corresponding vascular territory were visually classified into three patterns: no abnormality, focal abnormality, and territorial abnormality.

RESULTS

No DWI lesions were evident in initial MRI in 345 of the 443 TIA patients. Follow-up DWI was applied to 87 of these 345 DWI-negative TIA patients. Initial PWI abnormalities were significantly associated with follow-up DWI abnormalities: 8 of 43 patients with no PWI abnormalities (18.6%) had new ischemic lesions, whereas 13 of 16 patients with focal perfusion abnormalities (81.2%) had new ischemic lesions in the areas of initial PWI abnormalities [odds ratio (OR)=15.1, 95% confidence interval (CI)=3.6-62.9], and 14 of 28 patients with territorial perfusion abnormalities (50%) had new lesions (OR=3.7, 95% CI=1.2-11.5).

CONCLUSIONS

PWI is useful in defining whether or not the transient neurological symptoms in DWI-negative TIA are true vascular events, and will help to improve the understanding of the pathomechanism of TIA.

Neurodegeneration and Pathology in Epilepsy: Clinical and Basic Perspectives

Epilepsy is commonly associated with a number of neurodegenerative and pathological alterations in those areas of the brain that are involved in repeated electrographic seizures. These most prominently include neuron loss and an increase in astrocyte number and size but may also include enhanced blood-brain barrier permeability, the formation of new capillaries, axonal sprouting, and central inflammation. In animal models in which seizures are either repeatedly elicited or are self-generated, a similar set of neurodegenerative and pathological alterations in brain anatomy are observed. The primary causal agent responsible for these alterations may be the cascade of events that follow a seizure and lead to an hypoperfusion/hypoxic episode. While epilepsy has long and correctly been considered an electrical disorder, the vascular system likely plays an important causal role in the neurodegeneration and pathology that occur as a consequence of repeated seizures.

Impact of the New American Heart Association/American Stroke Association Definition of Stroke on the Results of the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis Trial

BACKGROUND

An American Heart Association/American Stroke Association (AHA/ASA) writing committee has recently recommended that tissue evidence of cerebral infarction associated with temporary symptoms (CITS) lasting <24 hours should be considered a stroke. We analyzed the impact of considering CITS as equivalent to stroke on the results of the Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial.

METHODS

We compared outcomes in the medical (n = 227) and stenting (n = 224) groups in SAMMPRIS using the following primary end point (new components in bold): any stroke, CITS, or death within 30 days after enrollment or within 30 days after a revascularization procedure for the qualifying lesion during follow-up; or ischemic stroke or CITS in the territory of the qualifying artery beyond 30 days. We also compared the use of brain magnetic resonance imaging (MRI) after transient ischemic attacks (TIAs) in both treatment groups.

RESULTS

By considering CITS as equivalent to stroke, the number of primary end points increased from 34 to 43 in the medical group and from 52 to 66 in the stenting group of SAMMPRIS. The Kaplan-Meier curves for the primary end points in the 2 groups were significantly different (P = .009). The percentage of patients with reported TIAs who underwent brain MRI was 69% in the medical group and 61% in the stenting group (P = .40).

CONCLUSION

Using the AHA/ASA definition of stroke resulted in a substantially higher primary end point rate in both treatment groups and an even higher benefit from medical therapy over stenting than originally shown in SAMMPRIS. The higher rate of CITS in the stenting group was not due to ascertainment bias.

Multimodal imaging in acute ischemic stroke

OPINION STATEMENT

Recent years have seen the development of novel neuroimaging techniques whose roles in the management of acute stroke are sometimes confusing and controversial. This may be attributable in part to a focus on establishing simplified algorithms and terminology that omit consideration of the basic pathophysiology of cerebral ischemia and, consequently, of the full potential for optimizing patients' care based upon their individual imaging findings. This review begins by discussing cerebral hemodynamic physiology and of the effects of hemodynamic disturbances upon the brain. Particular attention will be paid to the hemodynamic measurements and markers of tissue injury that are provided by common clinical imaging techniques, with the goal of enabling greater confidence and flexibility in understanding the potential uses of these techniques in various clinical roles, which will be discussed in the remainder of the review.

An assessment of the cost-effectiveness of magnetic resonance, including diffusion-weighted imaging, in patients with transient ischaemic attack and minor stroke: a systematic review, meta-analysis and economic evaluation

BACKGROUND

Patients with transient ischaemic attack (TIA) or minor stroke need rapid treatment of risk factors to prevent recurrent stroke. ABCD2 score or magnetic resonance diffusion-weighted brain imaging (MR DWI) may help assessment and treatment.

OBJECTIVES

Is MR with DWI cost-effective in stroke prevention compared with computed tomography (CT) brain scanning in all patients, in specific subgroups or as 'one-stop' brain-carotid imaging? What is the current UK availability of services for stroke prevention?

DATA SOURCES

Published literature; stroke registries, audit and randomised clinical trials; national databases; survey of UK clinical and imaging services for stroke; expert opinion.

REVIEW METHODS

Systematic reviews and meta-analyses of published/unpublished data. Decision-analytic model of stroke prevention including on a 20-year time horizon including nine representative imaging scenarios.

RESULTS

The pooled recurrent stroke rate after TIA (53 studies, 30,558 patients) is 5.2% [95% confidence interval (CI) 3.9% to 5.9%] by 7 days, and 6.7% (5.2% to 8.7%) at 90 days. ABCD2 score does not identify patients with key stroke causes or identify mimics: 66% of specialist-diagnosed true TIAs and 35-41% of mimics had an ABCD2 score of ≥ 4; 20% of true TIAs with ABCD2 score of < 4 had key risk factors. MR DWI (45 studies, 9078 patients) showed an acute ischaemic lesion in 34.3% (95% CI 30.5% to 38.4%) of TIA, 69% of minor stroke patients, i.e. two-thirds of TIA patients are DWI negative. TIA mimics (16 studies, 14,542 patients) make up 40-45% of patients attending clinics. UK survey (45% response) showed most secondary prevention started prior to clinic, 85% of primary brain imaging was same-day CT; 51-54% of patients had MR, mostly additional to CT, on average 1 week later; 55% omitted blood-sensitive MR sequences. Compared with 'CT scan all patients' MR was more expensive and no more cost-effective, except for patients presenting at > 1 week after symptoms to diagnose haemorrhage; strategies that triaged patients with low ABCD2 scores for slow investigation or treated DWI-negative patients as non-TIA/minor stroke prevented fewer strokes and increased costs. 'One-stop' CT/MR angiographic-plus-brain imaging was not cost-effective.

LIMITATIONS

Data on sensitivity/specificity of MR in TIA/minor stroke, stroke costs, prognosis of TIA mimics and accuracy of ABCD2 score by non-specialists are sparse or absent; all analysis had substantial heterogeneity.

CONCLUSIONS

Magnetic resonance with DWI is not cost-effective for secondary stroke prevention. MR was most helpful in patients presenting at > 1 week after symptoms if blood-sensitive sequences were used. ABCD2 score is unlikely to facilitate patient triage by non-stroke specialists. Rapid specialist assessment, CT brain scanning and identification of serious underlying stroke causes is the most cost-effective stroke prevention strategy.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Diffusion-weighted lesions in stroke patients with transient symptoms--where are they located?

BACKGROUND

MR diffusion-weighted imaging (DWI) has revolutionized neuroimaging and contributed to a tissue-based redefinition of transient ischemic attack (TIA). Stroke patients with DWI lesions may have neurological symptoms that resolve completely within 24 h, suggesting successful vessel recanalization. Prior studies of stroke patients with transient symptoms have not found any predilection for DWI lesions in any specific territory. Other studies have, however, reported an association between higher brain dysfunction and presence of DWI lesions in patients with transient ischemic symptoms, suggesting a high rate of cortical affection in these patients. We sought to see whether DWI location in stroke patients with transient symptoms <24 h differed from those with persistent symptoms ≥ 24 h. We hypothesized an association between transient symptoms <24 h and cortical DWI lesion localization due to a possible higher rate of vessel recanalization in patients with transient symptoms causing distal cortical infarctions.

METHODS

Ischemic stroke patients examined with DWI and admitted within 24 h after symptom onset between February 2006 and November 2013 were prospectively registered in a database (The Bergen NORSTROKE Registry). Based on neurological examination 24 h after admission, patients were classified as having either transient symptoms <24 h (DWI <24) or persistent symptoms ≥ 24 h (DWI ≥ 24). DWI lesions were classified into different groups depending on lesion location: cortical lesions, confined to the supratentorial cortex; large subcortical lesions, located in the hemispheric white matter, basal ganglia, internal capsule, thalamus or corona radiate with a diameter ≥ 15 mm; lacunar lesions, located in the same territory as large subcortical lesions with a diameter <15 mm; mixed cortical-subcortical lesions, located in both supratentorial cortex and subcortex; cerebellar lesions, confined to the cerebellum; brain stem lesions, confined to the brain stem; multiple locations, located in more than one of the above defined areas.

RESULTS

A total of 142 ischemic stroke patients had DWI <24 and 830 DWI ≥ 24. Cortical DWI location was more frequent in patients with DWI <24 (54.2% vs. 29.5%, p < 0.001), while proportions of mixed cortical-subcortical lesions (13.4% vs. 26.5%, p = 0.001) and lesions with multiple locations (5.6% vs. 11.1%, p = 0.048) were less frequent as compared to DWI ≥ 24. Cortical DWI location was independently associated with DWI <24 when adjusted for confounders in multiple regression analyses (OR 1.89, 95% CI 1.28-2.81, p = 0.001).

CONCLUSION

Cortical DWI location was independently associated with transient stroke symptoms <24 h. This may be explained by vessel recanalization, resulting in upstream transportation of remaining particles and distal cortical lesions.

Factors Associated with Cognitive Decline in Transient Ischemic Attack Patients

Chronic cerebrovascular disease and large ischemic stroke are both associated with cognitive impairment. Much less is known about the acute cognitive sequelae of transient ischemic attack (TIA). Although often overlooked, there is increasing evidence that cognitive impairment does occur following TIA. In some patients, cognitive changes persist after resolution of focal neurological deficits, but the temporal profile of these symptoms is unknown. In addition, clinical and imaging correlates of cognitive impairment after TIA have not been systematically studied. This under-studied and recognized problem has significant implications for TIA patient management. In this review, we summarize the evidence currently available and identify future research priorities.

Clinical implications of increased use of MRI in TIA

BACKGROUND

Transient ischemic attack has been redefined as a tissue-based diagnosis and MRI recommended as the preferred imaging modality. We aimed to investigate whether an increased use of MRI leads to a decrease in the proportion of TIA as compared to cerebral infarction. We also sought to see whether DWI-positive patients with transient ischemic symptoms <24 h differ from DWI-negative TIA patients in terms of performed diagnostic investigations and clinical characteristics.

METHODS

Patients admitted with cerebral infarction or TIA in the period 2006-2011 were prospectively registered. The use of MRI in patients with transient ischemic symptoms <24 h and proportion of TIA were annually recorded. DWI-positive and DWI-negative patients with transient ischemic symptoms <24 h were compared in univariate analyses regarding baseline data, diagnostic investigations, and etiology. Multivariate analyses were performed to identify predictors of DWI lesions.

RESULTS

The use of MRI increased from 65.0% in 2006-2008 to 89.0% in 2009-2011 (P < 0.001). The proportion of TIA as compared to cerebral infarction decreased from 12.2% in 2006-2008 to 8.3% in 2009-2011 (P = 0.002). DWI-positive patients were more often examined with 24-h Holter monitoring (P < 0.001) and echocardiography (P < 0.001). Lower age (P < 0.001) and prior myocardial infarction (P < 0.029) were independently associated with DWI lesions in patients with transient ischemic symptoms <24 h.

CONCLUSIONS

An increased use of MRI and a tissue-based TIA definition resulted in a decrease in the proportion of TIA at discharge as compared to cerebral infarction. DWI-positive patients had a more extensive cardiac work-up and were associated with lower age and prior myocardial infarction.

Improving detection of ischemic lesions at 3 Tesla with optimized diffusion-weighted magnetic resonance imaging

BACKGROUND AND PURPOSE

This study compared three different combinations of DWI parameters: three and six diffusion imaging directions (3dir and 6dir, respectively) using b=1000 or 2000 s/mm(2) (b1000 or b2000, respectively) to improve detection of recent ischemic lesions at 3 Tesla (3 T).

MATERIALS AND METHODS

A total of 47 consecutive patients underwent three DWI scans: 3dir b1000; 6dir b1000; and 6dir b2000. Qualitative visual analysis was performed by three readers based on evaluation of the number of lesions, presence of artifacts and diagnostic confidence. Interobserver agreement, sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

Forty-five lesions were detected by 3dir b1000, 52 by 6dir b1000 and 56 by 6dir b2000 in 30 patients. The additional lesions identified by 6dir b2000 were either small or located in the posterior fossa. Sensitivity with 6dir b2000 was significantly higher than with 3dir b1000 (98.1% vs 77.4%; P<0.05).

CONCLUSION

At 3 T, 6dir b2000 DWI detected more acute ischemic lesions than 3dir b1000, particularly small lesions and those located in the brain stem.

The incidence and clinical predictors of acute infarction in patients with transient ischemic attack using MRI including DWI

INTRODUCTION

According to the most recent definition of transient ischemic attack (TIA) and the recommendations of the American Heart Association, magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) is considered a mandatory tool in evaluating and treating patients with TIA. This study aims to determine the incidence of TIA-related acute infarction, identify the independent predictors of acute infarction, and investigate the correlation between acute infarction detected by DWI-MRI and stroke risk during hospitalization.

METHODS

Over a 36-month period (starting November 2007), all TIA patients (symptom duration of <24 h) who were admitted to hospital within 48 h of symptom onset and who underwent DWI-MRI were included in this population-based prospective study. The incidence of acute infarction, clinical predictors, and association with stroke recurrence during hospitalization were studied.

RESULTS

Of 1,910 patients (mean age, 66.7 ± 13 years; 46 % women), 1,862 met the inclusion criteria. A TIA-related acute infarction was detected in 206 patients (11.1 %). Several independent predictors were identified with logistic regression analysis: motor weakness [odds ratio (OR), 1.5], aphasia (OR, 1.6), National Institutes of Health Stroke Scale (NIHSS) score of ≥10 at admission (OR, 3.2), and hyperlipidemia (OR, 0.6). Of 24 patients (1.3 %) who suffered a stroke during hospitalization (mean, 6 ± 4 days), five had positive DWI. Stroke rate during hospitalization was nonsignificantly higher in patients with positive DWI than those with negative DWI (2.4 vs 1.1 %, respectively; P = 0.12).

CONCLUSION

The evidence of acute infarction by DWI-MRI in TIA patients was detected in 11.1 % of patients and associated with motor weakness, aphasia, and NIHSS score of ≥10 at admission.

Thrombolytic Therapy for Acute Ischemic Stroke after Recent Transient Ischemic Attack

Background and aim

Safety and efficacy of intravenous thrombolysis in stroke patients with recent transient ischemic attack are hotly debated. Patients suffering transient ischemic attack may present with diffusion-weighted imaging lesions, and although normal computed tomography would not preclude thrombolysis, the concern is that they may be at higher risk for hemorrhage ***post-thrombolysis treatment. Prior ipsilateral transient ischemic attack might provide protection due to ischemic preconditioning. We assessed post-thrombolysis outcomes in stroke patients who had prior transient ischemic attack.

Methods

Multicentered prospective study of consecutive acute stroke patients treated with intravenous tissue plasminogen activator (tPA). Ipsilateral transient ischemic attack, baseline characteristics, risk factors, etiology, and time-lapse to treatment were recorded. National Institutes of Health Stroke Scale at seven-days and modified Rankin Scale at three-months, symptomatic intracranial hemorrhage, and mortality were compared in patients with and without transient ischemic attack.

Results

There were 877 patients included, 60 (6.84%) had previous ipsilateral transient ischemic attack within ***one-month prior to the current stroke (65% in the previous 24 h). Transient ischemic attack patients were more frequently men (70% vs. 53%; P = 0.011), younger (63 vs. 71 years of age; P = 0.011), smokers (37% vs. 25%; P = 0.043), and with large vessel disease (40% vs. 25%; P = 0.011). Severity of stroke at onset was similar to those with and without prior transient ischemic attack (median National Institutes of Health Stroke Scale score 12 vs. 14 P = 0.134). Those with previous transient ischemic attack were treated earlier (117 $pL 52 vs. 144 $pL 38 mins; P #< 0.005). After adjustment for confounding variables, regression analysis showed that previous transient ischemic attack was not associated with differences in stroke outcome such as independence (modified Rankin Scale 0–2) (odds ratios: 1.035 (0.57–1.93) P = 0.91), mortality (odds ratios: 0.99 (0.37–2.67) P = 0.99), or symptomatic intracranial hemorrhage (odds ratios: 2.04 (0.45–9.32) P = 0.36).

Conclusions

Transient ischemic attack preceding ischemic stroke does not appear to have a major influence on outcomes following thrombolysis. Patients with prior ipsilateral transient ischemic attack appear not to be at higher risk of bleeding complications.

Acute perfusion and diffusion abnormalities predict early new MRI lesions 1 week after minor stroke and transient ischemic attack

BACKGROUND AND PURPOSE

Transient ischemic attack and minor stroke are associated with high ischemic recurrence in the first week. We prospectively studied the correlation between baseline diffusion/perfusion deficits and development of new ischemic lesions.

METHODS

Patients with transient ischemic attack and those with minor stroke (n=50) underwent MRI at admission. Acute perfusion-weighted imaging deficit (Tmax+2-second delay) and diffusion-weighted imaging (DWI) lesion volumes were measured planimetrically. Follow-up scans were examined for new DWI/fluid-attenuated inversion recovery lesions at Days 7 and 30.

RESULTS

Twenty-eight patients (56%) had acute DWI lesions. New DWI lesions developed in 9 of 50 patients (18%) at 1 week and 11 of 50 (cumulative 22%) at 4 weeks. Patients with new infarcts were more likely to have baseline DWI lesions (χ²=8.264, P=0.003). Baseline DWI lesion volume was significantly larger in those who developed new lesions at Day 7 (median, 13.2 mL; interquartile range, 12 versus median 0.1 mL; interquartile range, 2 mL; P<0.001) and Day 30 (11.1 mL; interquartile range, 13 mL versus 0.1 mL; interquartile range, 13 mL; P<0.001). Thirty-eight patients had baseline perfusion-weighted imaging. Patients with recurrent lesions were more likely to have baseline perfusion deficits (χ²=19.5, P<0.0001). All new lesions developed within the baseline hypoperfused regions. Baseline DWI lesion volume predicted new lesion development at day 7 (OR, 1.17 per mL; CI, 1.05 to 1.30; P=0.005) and Day 30 (OR, 1.39 per mL; CI, 1.03 to 1.26; P=0.009) by regression analysis.

CONCLUSIONS

Early recurrence of stroke is much more likely in patients with larger baseline DWI and perfusion-weighted imaging lesions. MRI lesion "recurrence" appears to be related to completion of the natural history of the original cerebrovascular syndrome rather than de novo events in most patients.

[Diffusion-weighted MR imaging of the brain]

Imaging of water diffusion or diffusion-weighted MR imaging provides physiological information about brain diseases that cannot be obtained from conventional sequences. This technique is very sensitive for the detection of cerebral ischemia from arterial origin and can distinguish cerebral ischemia from other non-vascular brain pathologies in patients presenting with abrupt onset of focal neurological deficit. Diffusion-weighted imaging is used for the evaluation of non-vascular diseases as well. Combined with conventional sequences, it is helpful to differentiate brain abscesses from necrotic tumors. Quantitative diffusion-weighted imaging provides additional information in the characterization of tumors or inflammatory, degenerative and metabolic lesions. Finally, diffusion-weighted imaging data also has prognostic value.

Yield of combined perfusion and diffusion MR imaging in hemispheric TIA

OBJECTIVE

Transient ischemic attacks (TIA) predict future stroke. However, there are no sensitive and specific diagnostic criteria for TIA and interobserver agreement regarding the diagnosis is poor. Diffusion-weighted MRI (DWI) demonstrates acute ischemic lesions in approximately 30% of TIA patients; the yield of perfusion-weighted MRI (PWI) is unclear.

METHODS

We prospectively performed both DWI and PWI within 48 hours of symptom onset in consecutive patients admitted with suspected hemispheric TIAs of <24 hours symptom duration. Two independent raters, blinded to clinical features, assessed the presence and location of acute DWI and PWI lesions. Lesions were correlated with suspected clinical localization and baseline characteristics. Clinical features predictive of a PWI lesion were assessed.

RESULTS

Forty-three patients met the inclusion criteria. Thirty-three percent had a PWI lesion and 35% had a DWI lesion. Seven patients (16%) had both PWI and DWI lesions and 7 (16%) had only PWI lesions. The combined yield for identification of either a PWI or a DWI was 51%. DWI lesions occurred in the clinically suspected hemisphere in 93% of patients; PWI lesions in 86%. PWI lesions occurred more frequently when the MRI was performed within 12 hours of symptom resolution, in patients with symptoms of speech impairment, and among individuals younger than 60 years.

CONCLUSIONS

The combination of early diffusion-weighted MRI and perfusion-weighted MRI can document the presence of a cerebral ischemic lesion in approximately half of all patients who present with a suspected hemispheric transient ischemic attack (TIA). MRI has the potential to improve the accuracy of TIA diagnosis. ACA = anterior cerebral artery; CI = confidence interval; DWI = diffusion-weighted MRI; ICA = internal carotid artery; MCA = middle cerebral artery; MRA = magnetic resonance angiography; MTT = mean transit time; OR = odds ratios; PCA = posterior cerebral artery; PWI = perfusion-weighted MRI; RR = risk ratios; TIA = transient ischemic attacks; TOAST = Trial of Org 10172 in Acute Stroke Treatment.

DWI lesions and TIA etiology improve the prediction of stroke after TIA

BACKGROUND AND PURPOSE

The ABCD(2) score has been shown to predict the early risk of stroke after transient ischemic attack (TIA). The additional predictive value of diffusion-weighted imaging (DWI) and TIA etiology is not well known.

METHODS

From January 2003 to June 2007, 343 consecutive patients (mean+/-SD age, 62.4+/-15.4 years) with TIA were admitted to our stroke unit. Most (339) patients underwent DWI and all had an etiologic work-up and were followed up for 3 months. The predictive value of the ABCD(2) score, positive DWI findings, large-artery atherosclerosis (LAA), and atrial fibrillation (AF) with respect to occurrence of ischemic stroke at 1 week and 3 months was assessed.

RESULTS

DWI was positive in 136 (40%) patients. Sixty (17%) patients had LAA and 27 (8%) had AF. Patients with positive DWI findings were more likely to have unilateral weakness (odds ratio [OR]=2.2; 95% CI, 1.3 to 3.7), TIA duration >/=60 minutes (OR=2.6; 95% CI, 1.3 to 5.2), ABCD(2) >5 (OR=4.7; 95% CI, 2.0 to 11.0), LAA (OR=1.8; 95% CI, 1.0 to 3.1), and AF (OR=3.5; 95% CI, 1.5 to 8.0). During follow-up, 5 patients had a stroke within 7 days (absolute risk=1.5%, 95% CI, 0.3% to 2.7%), and 10 had a stroke within 3 months (absolute risk=2.9%; 95% CI, 1.1% to 4.7%). All early strokes but 1 occurred in patients with positive DWI findings. ABCD(2) score and positive DWI findings were associated with an increased 7-day and 3-month risk of stroke. At 3 months, ABCD(2) score >5 (hazard ratio=10.1; 95% CI, 1.1 to 93.4), positive DWI result (hazard ratio=8.7; 95% CI, 1.1 to 71.0), and LAA (hazard ratio=3.4; 95% CI, 1.0 to 11.8) were independently associated with an increased risk of stroke. There was no association with AF.

CONCLUSIONS

Taking DWI and TIA etiology into account in addition to the ABCD(2) score improves the prediction of the early risk of stroke after TIA.

Prevalence and correlates of silent cerebral infarcts in the Framingham offspring study

BACKGROUND AND PURPOSE

Previous estimates of the prevalence of silent cerebral infarction (SCI) on MRI in community-based samples have varied between 5.8% and 17.7% depending on age, ethnicity, presence of comorbidities, and imaging techniques. We document the prevalence and risk factors associated with SCI at midlife in the community-based Framingham sample.

METHODS

Our study sample comprised 2040 Framingham Offspring (53% female; mean age, 62+/-9 years) who attended the sixth examination (1996-1998), underwent volumetric brain MRI (1999-2005,) and were free of clinical stroke at MRI. We examined the age- and sex-specific prevalences and the clinical correlates of SCI using multivariable logistic regression models.

RESULTS

At least 1 SCI was present in 10.7% of participants; 84% had a single lesion. SCI was largely located in the basal ganglia (52%), other subcortical (35%) areas, and cortical areas (11%). Prevalent SCI was associated with the Framingham Stroke Risk Profile score (OR, 1.27; 95% CI, 1.10-1.46); stage I hypertension was determined by JNC-7 criteria (OR,1.56; CI,1.15-2.11), an elevated plasma homocysteine in the highest quartile (OR, 2.23; CI, 1.42-3.51), atrial fibrillation (OR, 2.16; CI, 1.07-4.40), carotid stenosis >25% (OR, 1.62; 1.13-2.34), and increased carotid intimal-medial thickness above the lowest quintile (OR, 1.65; CI, 1.22-2.24).

CONCLUSIONS

The prevalence and distribution of SCI in the Framingham Offspring are comparable to previous estimates. Risk factors previously associated with clinical stroke were also found to be associated with midlife SCI. Our results support current guidelines emphasizing early detection and treatment of stroke risk factors.

Diffusion-weighted magnetic resonance imaging at 3.0 Tesla in alcohol intoxication

Acute alcohol intake has pronounced effects on brain function. However, the exact mechanism of action is unclear. Diffusion Magnetic Resonance Imaging (dwMRI) can detect subtle changes in microstructural neural states. Here we tested if dwMRI can detect such changes during alcohol intoxication. We used high-field dwMRI in four healthy subjects at different blood alcohol concentration (0.0 g/L, 0.3 g/L, 0.6 g/L and 1.0 g/L). Although neuropsychological performances declined markedly, no changes in diffusion parameters emerged. First, this finding argues against alcohol-induced diffuse changes of microstructural state and in favour of more specific, possibly receptor-mediated actions of alcohol on brain function. Second, processes involving neurotransmitters that are primarily linked to cognitive function might not be viewable with high-field diffusion MRI.

Clinical impact of MRI perfusion disturbances and normal diffusion in acute stroke patients

PURPOSE

In acute ischemic stroke MR-imaging typically shows diffusion abnormalities surrounded by reduced perfusion signifying the so-called ischemic penumbra. Mismatch between diffusion and perfusion abnormalities gives indication for thrombolysis. But is there an indication for thrombolytic treatment, if there is no diffusion abnormality but pathologic perfusion combined with acute stroke symptoms?.

MATERIAL AND METHODS

MR-imaging of 1465 patients treated on our Stroke Unit between June 2004 and May 2007 retrospectively are analyzed. 6 patients met the inclusion criteria of severe neurological symptoms, large territorial perfusion disturbances, lack of diffusion abnormalities and complete neurological recovery after treatment.

RESULTS

In all six patients MTT measurements showed a significantly depressed perfusion in the symptomatic hemisphere (p<0.02). Time-to-peak delay correlated with the mean transit time delay (0.949, p<0.01). Indication for thrombolysis was based on perfusion abnormalities and clinical symptoms. Stroke symptoms could be reversed in all patients without any complication.

CONCLUSION

Whereas diffusion imaging could not reveal any abnormality, perfusion analysis legitimated therapy with systemic thrombolysis in heavily affected patients. This work underlines the importance of multimodal MR imaging for guiding treatment decisions in acute stroke patients.

Detection of peritoneal dissemination in gynecological malignancy: evaluation by diffusion-weighted MR imaging

The aim of this study is to evaluate the usefulness of diffusion-weighted (DW) magnetic resonance (MR) imaging in detecting peritoneal dissemination in cases of gynecological malignancy. We retrospectively analyzed MR images obtained from 26 consecutive patients with gynecological malignancy. Peritoneal dissemination was histologically diagnosed in 15 of the 26 patients after surgery. We obtained DW images and half-Fourier single-shot turbo-spin-echo images in the abdomen and pelvis, and then generated fusion images. Coronal maximum-intensity-projection images were reconstructed from the axial source images. Reader interpretations were compared with the laparotomy findings in the surgical records. Receiver-operating characteristic (ROC) curves were used to represent the presence of peritoneal dissemination. In addition, the sensitivity and specificity were calculated. DW imaging depicted the tumors in 14 of 15 patients with peritoneal dissemination as abnormal signal intensity. ROC analysis yielded Az values of 0.974 and 0.932 for the two reviewers. The mean sensitivity and specificity were 90 and 95.5%. DW imaging plays an important role in the diagnosis and therapeutic management of patients with gynecological malignancy.

Management and Outcome of Patients with Transient Ischemic Attack Admitted to a Stroke Unit

BACKGROUND

The way in which patients with transient ischemic attack (TIA) are investigated and treated varies substantially worldwide. There are no data on the management and outcome of TIA patients admitted to a stroke unit. We assessed to what extent rapid management of TIA patients admitted to a stroke unit led to specific treatments which can prevent stroke and evaluated the early risk and predictors of stroke in these patients.

METHODS

From January 2003 to November 2005, 203 consecutive patients with a recent (<48 h) TIA were admitted to our stroke unit. All patients had a diffusion-weighted imaging (DWI) on admission, a standardized etiological workup, and were followed up to 3 months.

RESULTS

The median (interquartile range) time from TIA onset to admission to the stroke unit was 12 h (5-25). DWI revealed acute lesions in 64 patients (32%). Of the 203 patients, 147 (72%) were treated by antiplatelet therapy and 56 (28%) with high doses of heparin, soon after their admission. In addition, 7 patients (3%) had a carotid revascularization. The risk of stroke was 2.5% (95% CI, 0.3-4.7) at 1 week, and 3.5% (1.0-6.1) at 3 months. In multivariate analysis, a score > or =5 at the previously validated ABCD score (HR = 5.0; 1.0-25.8; p = 0.06) and the presence of DWI abnormalities (HR = 10.3; 1.2-86.7; p = 0.03) were independent predictors of stroke at 3 months.

CONCLUSION

Early management of TIA in a stroke unit leads to specific treatments in a significant proportion of cases. The presence of acute lesions on DWI and the ABCD score predict the 3-month risk of stroke after TIA.

Sudden bilateral blindness in Wernicke's encephalopathy: case report and review of the literature

We report on a patient suffering from bilateral sudden blindness as initial symptom of Wernicke's encephalopathy (WE). A 37-year-old male alcoholic was admitted to a psychiatric clinic because of excessive alcohol consumption (3.4 per thousand). 24 h later he developed acute bilateral blindness with no light perception, downbeat nystagmus, bilateral ocular abduction deficits, cerebellar ataxia as well as a slight psychomotor slowing and mild disorientation. MRI including diffusion-weighted imaging and MR-angiography 3 h after symptom onset did not reveal findings suggestive for ischemic stroke. Immediate iv-application of thiamine led to a nearly complete remission of the neuroophthalmologic symptoms within 12 h. Although we critically discuss other potential etiologies, we conclude that the complex clinical picture with initial sudden blindness is an unusual presentation of WE.

Systematic Review of Associations Between the Presence of Acute Ischemic Lesions on Diffusion-Weighted Imaging and Clinical Predictors of Early Stroke Risk After Transient Ischemic Attack

BACKGROUND AND PURPOSE

Early risk of stroke after a transient ischemic attack can be reliably predicted with risk scores based on clinical features of the patient and of the ischemic event, but it is unclear how these features correlate with findings on brain imaging.

METHODS

We performed a systematic review of the literature and identified all previous studies which reported patient characteristics and the nature of transient ischemic attack symptoms in relation to appearances on diffusion-weighted imaging (DWI). We then performed a meta-analysis of the associations between the components of the risk scores and positive DWI. Authors were contacted for additional unpublished data.

RESULTS

Nineteen studies were identified by the systematic review, and additional unpublished data were obtained from 11 of these studies. On meta-analysis, several components of the risk scores were associated with positive DWI, including symptom duration > or =60 minutes (13 studies, odds ratio [OR], 1.50; 95% CI, 1.16 to 1.96; P=0.004), dysphasia (9 studies, OR, 2.25; 95% CI, 1.57 to 3.22; P<0.001), dysarthria (8 studies, OR, 1.73; 95% CI, 1.11 to 2.68; P=0.03) and motor weakness (9 studies, OR, 2.20; 95% CI, 1.56 to 3.10; P<0.001). However patient age, sex, hypertension and diabetes were not associated with the presence of DWI lesions. From an etiologic perspective, atrial fibrillation (9 studies, OR, 2.75; 95% CI, 1.78 to 4.25; P<0.001) and ipsilateral > or =50% carotid stenosis (10 studies, OR, 1.93; 95% CI, 1.34 to 2.76; P=0.001) were associated with positive DWI.

CONCLUSIONS

Presence of acute ischemic lesions on DWI correlates with several clinical features known to predict stroke risk after transient ischemic attack. Large studies (sample size >1000) will therefore be required to determine the independent prognostic value of DWI and its interactions with these clinical characteristics.

Reversible brain ischemia: lessons from transient ischemic attack

PURPOSE OF REVIEW

In recent years, there has been considerable scientific inquiry regarding transient ischemic attack. In an effort to synthesize at times conflicting data, this paper will review the recent evidence and provide a critical overview of reversible brain ischemia.

RECENT FINDINGS

Transient ischemic attack is now understood to indicate a higher risk of recurrence than completed ischemic stroke. Efforts to unravel the mechanisms of this instability following transient ischemic attack using imaging studies have led to new concepts and definitions, and sparked further debate. While imaging has increased diagnostic certainty, it has yet to provide reliable prognostic markers. The evidence suggests that risk of clinical recurrence is most closely linked to the degree to which the initial deficit reverses. From a tissue level, however, there are also data to support the notion of a 'stroke-prone state' following both transient ischemic attack and completed stroke, suggesting that mechanistically they may be less distinct than previously thought. Transient ischemic attack may simply highlight the dynamic nature of all acute ischemic cerebrovascular syndromes.

SUMMARY

Reversible brain ischemia is a harbinger for subsequent ischemic stroke. Although recent advances have focused on imaging markers, the most important predictor of risk following brain ischemia is degree of early clinical reversibility.

Imagerie de diffusion : principes et applications cliniques

Diffusion MRI gives information that is not available with conventional MRI examinations. It can provide early diagnosis of stroke and helps in diagnosing cerebral lymphoma, cerebral bacterial abscess, and epidermoid cyst. It helps distinguish between vasogenic edema and cytotoxic edema and has prognostic value. Acquisition is fast and should be performed in all neuroradiological examinations.

The frequency of symptoms in transient ischaemic attack: analysis of Nanjing Stroke Register Program data

The clinical characteristics of 172 patients experiencing single or multiple (two or more) transient ischaemic attacks (TIAs) were investigated. Risk factors, clinical manifestations and vascular examinations were compared. Intracranial and extra-cranial large-artery disease (stenosis > or = 50%) occurred more frequently in multiple-TIA patients than in single-TIA patients, and weakness and atrial fibrillation were observed more frequently in single TIA than in multiple TIA patients. The type of aetiological examination performed in TIA patients should depend on the frequency of attacks.

[Imaging techniques in diagnosis of brainstem infarction]

Twenty per cent of cerebral ischaemic infarctions involve tissue, supplied by the vertebrobasilar circulation. This overview of the current literature and our own experiences present the value of different imaging techniques (CT and MRI) and new developments for diagnosing brainstem infarction. Furthermore, the roles of invasive and noninvasive vascular imaging methods (computed tomographic angiography, magnetic resonance angiography, intra-arterial angiography, ultrasound) for evaluating vertebrobasilar stenosis and occlusion are described. The diagnostic workup of the most severe form of brainstem infarction, basilar artery thrombosis, is shown.