Magnetic resonance brain imaging in patients with acute stroke: feasibility and patient related difficulties

The importance of multimodal CT examination in stroke mimics diagnosis: design of prospective observational multicentre study

Introduction

Non-contrast computed tomography (CT) and CT angiography are the gold standard in neuroimaging diagnostics in the case of suspected stroke. CT perfusion (CTP) may play an important role in the diagnosis of stroke mimics (SM), but currently, it is not a standard part of the stroke diagnostic procedure. The project is a multicentre prospective observational clinical research focused on refining the diagnostics of stroke and stroke mimics (SM) in hospital care.

Aim

This study aimed to evaluate the degree of specificity and sensitivity of multimodal CT (NCCT, CTA, and CTP) in the diagnosis of SM versus stroke.

Methodology

In this study, we will include 3,000 patients consecutively admitted to the comprehensive stroke centres with a diagnosis of suspected stroke. On the basis of clinical parameters and the results of multimodal CT and magnetic resonance imaging (MRI), the diagnosis of stroke and SM will be established. To clarify the significance of the use of the multimodal CT scan, the analysis will include a comparison of the blinded results for each imaging scan performed by radiologists and AI technology and a comparison of the initial and final diagnosis of the enrolled patients. Based on our results, we will compare the economic indicators and costs that would be saved by not providing inadequate treatment to patients with SM.

Conclusion

The expected outcome is to present an optimised diagnostic procedure that results in a faster and more accurate diagnosis, thereby eliminating the risk of inadequate treatment in patients with SM.

Clinical trial registration

clinicaltrials.gov, NCT06045455.

Understanding ASPECTS of stroke: Inter-rater reliability between emergency medicine physician and radiologist in a rural setup

PURPOSE

The purpose is to determine the inter-rater reliability in grading ASPECTS score, between emergency medicine physician at first contact and radiologist among patients with acute ischemic stroke.

MATERIALS AND METHODS

We conducted a prospective analysis of 765 acute ischemic stroke cases referred to the Department of Radiodiagnosis in a rural-based hospital in South India, during January 2017 to October 2021. Non-contrast computed tomography (NCCT) scans of the brain were performed using GE Bright Speed Elite 128 Slice CT Scanner. ASPECTS score was calculated separately by an emergency medicine physician and radiologist. Inter-rater reliability for total and dichotomized ASPECTS (≥6 and <6) scores were assessed using statistical analysis (ICC and Cohen ĸ coefficients) on SPSS software (v17.0).

RESULTS

Inter-rater agreement for total and dichotomized ASPECTS was substantial (ICC 0.79 and Cohen ĸ 0.68) between the emergency physician and the radiologist. Mean difference in ASPECTS between the two readers was only 0.15 with standard deviation of 1.58. No proportionality bias was detected. The Bland-Altman plot was constructed to demonstrate the distribution of ASPECTS differences between the two readers.

CONCLUSION

Substantial inter-rater agreement was noted in grading ASPECTS between emergency medicine physician at first contact and radiologist, thereby confirming its robustness even in a rural setting.

Risk assessment of the acute stroke diagnostic process using failure modes, effects, and criticality analysis

INTRODUCTION

To date, many emergency department (ED)-based quality improvement studies and interventions for acute stroke patients have focused on expediting time-sensitive treatments, particularly reducing door-to-needle time. However, prior to treatment, a diagnosis of stroke must be reached. The ED-based stroke diagnostic process has been understudied despite its importance in assuring high-quality and safe care.

METHODS

We used a learning collaborative to conduct a failure modes, effects, and criticality analysis (FMECA) of the acute stroke diagnostic process at three health systems in Chicago, IL. Our FMECA was designed to prospectively identify, characterize, and rank order failures in the systems and processes of care that offer opportunities for redesign to improve stroke diagnostic accuracy. Multidisciplinary teams involved in stroke care at five different sites participated in moderated sessions to create an acute stroke diagnostic process map as well as identify failures and existing safeguards. For each failure, a risk priority number and criticality score were calculated. Failures were then ranked, with the highest scores representing the most critical failures to be targeted for redesign.

RESULTS

A total of 28 steps were identified in the acute stroke diagnostic process. Iterative steps in the process include information gathering, clinical examination, interpretation of diagnostic test results, and reassessment. We found that failure to use existing screening scales to identify patients with large-vessel occlusions early on in their ED course ranked highest. Failure to obtain an accurate history of the index event, failure to suspect acute stroke in triage, and failure to use established stroke screening tools at ED arrival to identify potential stroke patients were also highly ranked.

CONCLUSIONS

Our study results highlight the critical importance of upstream steps in the acute stroke diagnostic process, particularly the use of existing tools to identify stroke patients who may be eligible for time-sensitive treatments.

Posterior Circulation ASPECTS on CT Angiography Predicts Futile Recanalization of Endovascular Thrombectomy for Acute Basilar Artery Occlusion

Background

Acute basilar artery occlusion (BAO) is the most potentially disastrous outcome and has a high risk of recurrence stroke in posterior circulation infarction (PCI). However, the rate of futile recanalization remains high despite successful recanalization. The objective of this study was to investigate 90 days functional outcomes among patients with BAO who underwent endovascular thrombectomy (EVT) and to identify the risk factors associated with futile recanalization.

Methods

We retrospectively analyzed 72 patients with acute BAO who received EVT from January 2018 to June 2021. CT angiography source images posterior circulation Acute Stroke Prognosis Early CT Score (CTA-SI pc-ASPECTS) evaluated the extensive hypoattenuation in patients with BAO. Futile recanalization defined an modified Rankin Scale (mRS) of 3-6 at 90 days despite a successful recanalization. Logistic regression analysis was performed to investigate the predictors of futile recanalization.

Results

Our sample included a total of 55 eligible patients. Patients with poor outcomes showed that the pc-ASPECTS score was lower in patients with poor outcomes than that in patients with good outcomes (P = 0.017). Longer time from symptoms onset-to-the puncture (P = 0.014) and elevation of leucocytes (P = 0.012) were associated with poor outcomes. The multivariable logistic analysis showed that pc-ASPECTS and onset-to-puncture time (OPT) were independent predictors of futile recanalization.

Conclusions

This study suggested that pc-ASPECTS and OPT are independent predictors of futile recanalization after EVT in patients with BAO. The lower pc-ASPECTS score and longer puncture time will have a poor clinical outcome.

Indian College of Radiology and Imaging (ICRI) Consensus Guidelines for the Early Management of Patients with Acute Ischemic Stroke: Imaging and Intervention

The medical science has witnessed significant change in the management of acute stroke patients as a result of recent advances in the field of stroke imaging and endovascular mechanical thrombectomy in addition to intravenous thrombolysis and optimization of stroke services in balance with available resources. Despite initial negative trials, we witnessed the publication of five multicenter randomized clinical trials showing superiority of the endovascular approach over standard medical management in patients with large vessel occlusion. The aim of this study is to provide comprehensive set of evidence-based recommendations regarding imaging and endovascular interventions in acute ischemic stroke patients.

Estimation of stroke severity with National Institutes of Health Stroke Scale grading and retinal features: A cross-sectional study

To estimate National Institutes of Health Stroke Scale (NIHSS) grading of stroke patients with retinal characteristics.A cross-sectional study was conducted in Shenzhen Traditional Chinese Medicine Hospital. Baseline information and retinal photos were collected within 2 weeks of admission. An NIHSS score was measured for each patient by trained doctors. Patients were classified into 0 to 4 score group and 5 to 42 score group for analysis. Three multivariate logistic models, with traditional clinical characteristics alone, with retinal characteristics alone, and with both, were built.For clinical characteristics, hypertension duration is statistically significantly associated with higher NIHSS score (P = .014). Elevated total homocysteine levels had an OR of 0.456 (P = .029). For retinal characteristics, the fractal dimension of the arteriolar network had an OR of 0.245 (P < .001) for the left eyes, and an OR of 0.417 (P = .009) for right eyes. The bifurcation coefficient of the arteriole of the left eyes had an OR of 2.931 (95% CI 1.573-5.46, P = .001), the nipping of the right eyes had an OR of 0.092 (P = .003) showed statistical significance in the model.The area under receiver-operating characteristic curve increased from 0.673, based on the model with clinical characteristics alone, to 0.896 for the model with retinal characteristics alone and increased to 0.931 for the model with both clinical and retinal characteristics combined.Retinal characteristics provided more information than clinical characteristics in estimating NIHSS grading and can provide us with an objective method for stroke severity estimation.

Cost-Effectiveness of Advanced Neuroimaging for Transient and Minor Neurological Events in the Emergency Department

Background Accurate diagnosis of patients with transient or minor neurological events can be challenging. Recent studies suggest that advanced neuroimaging can improve diagnostic accuracy in low-risk patients with transient or minor neurological symptoms, but a cost-effective emergency department diagnostic evaluation strategy remains uncertain. Methods and Results We constructed a decision-analytic model to evaluate 2 diagnostic evaluation strategies for patients with low-risk transient or minor neurological symptoms: (1) obtain advanced neuroimaging (magnetic resonance imaging brain and magnetic resonance angiography head and neck) on every patient or (2) current emergency department standard-of-care clinical evaluation with basic neuroimaging. Main probability variables were: proportion of patients with true ischemic events, strategy specificity and sensitivity, and recurrent stroke rate. Direct healthcare costs were included. We calculated incremental cost-effectiveness ratios, conducted sensitivity analyses, and evaluated various diagnostic test parameters primarily using a 1-year time horizon. Cost-effectiveness standards would be met if the incremental cost-effectiveness ratio was less than willingness to pay. We defined willingness to pay as $100 000 US dollars per quality-adjusted life year. Our primary and sensitivity analyses found that the advanced neuroimaging strategy was more cost-effective than emergency department standard of care. The incremental effectiveness of the advanced neuroimaging strategy was slightly less than the standard-of-care strategy, but the standard-of-care strategy was more costly. Potentially superior diagnostic approaches to the modeled advanced neuroimaging strategy would have to be >92% specific, >70% sensitive, and cost less than or equal to standard-of-care strategy's cost. Conclusions Obtaining advanced neuroimaging on emergency department patient with low-risk transient or minor neurological symptoms was the more cost-effective strategy in our model.

Integration of ultra-high-pressure liquid chromatography-tandem mass spectrometry with machine learning for identifying fatty acid metabolite biomarkers of ischemic stroke

We report for the first time the integration of ultra-high-pressure liquid chromatography-tandem mass spectrometry with machine learning for identifying fatty acid metabolite biomarkers of ischemic stroke. In particular, we develop an optimal model to discriminate ischemic stroke patients from healthy persons with 100% sensitivity and 93.18% specificity. This research may facilitate understanding the roles of fatty acid metabolites in stroke occurrence, holding great potential in clinical stroke diagnosis.

Emerging stroke systems of care in Germany

In order to reduce intrahospital times for stroke patients, we have implemented various strategies throughout the last 4 years. Swift restoration of cerebral perfusion is essential for the outcomes of patients with acute ischemic stroke. Endovascular treatment (EVT) has become the standard of care to accomplish this in patients with acute stroke due to large vessel occlusion (LVO). To achieve reperfusion of ischemic brain regions as fast as possible, all in-hospital time delays have to be avoided. Therefore management of patients with acute ischemic stroke was optimized with an interdisciplinary standard operating procedure (SOP). Stroke neurologists, diagnostic as well as interventional neuroradiologists, and anesthesiologists streamlined all necessary processes from patient admission and diagnosis to EVT of eligible patients. In a second step we established a one-stop management of stroke patients, meaning that imaging was acquired with the same angiography suite use for treatment of patients with LVO. In the last section of this chapter we discuss the latest trials on stroke therapy and their implications for our current triage systems and imaging patterns.

Perfusion computed tomography in posterior circulation stroke: predictors and prognostic implications of focal hypoperfusion

BACKGROUND AND PURPOSE

The aim was to determine the predictors of focal hypoperfusion on computed tomography (CT) perfusion (CTP) in patients with acute posterior circulation stroke and its association with long-term outcome.

METHODS

Patients with posterior circulation stroke were selected from the Acute Stroke Registry and Analysis of Lausanne (ASTRAL) who underwent CTP within 24 h of stroke onset as part of the stroke imaging protocol. Hypoperfusion was defined as an area of visually well demarcated mean transit time prolongation corresponding to an arterial territory on standard reconstruction CTP imaging maps. Areas of hypoperfusion were assessed with the posterior circulation Acute Stroke Prognosis Early CT Score. Clinical and imaging associations with focal hypoperfusion were identified using multiple imputation analyses, and the adjusted functional outcome measured by the modified Rankin Scale at 3 and 12 months was determined.

RESULTS

Of the 3595 consecutive patients from the ASTRAL registry between 2003 and 2014, 1070 (29.7%) had a posterior circulation stroke and 436 of these (40.7%) patients had a good quality baseline CTP. 23.1% had early ischaemic changes and 37.4% had focal hypoperfusion. In multiple imputation analysis, visual field deficits, reduced level of consciousness, cardiac and multiple stroke mechanisms, significant vessel pathology and ischaemic changes visible on plain CT were associated with focal hypoperfusion. Focal hypoperfusion was independently associated with outcome at 12 months (odds ratio 2.04, 95% confidence interval 1.22-3.42, P < 0.01).

CONCLUSIONS

In posterior circulation stroke patients undergoing acute CTP, multiple clinical, aetiological and radiological variables were associated with focal hypoperfusion. Patients with focal hypoperfusion had a worse 12-month outcome.

[The biomarkers of cerebral ischemia as a new method for the validation of the efficacy of cytoprotective therapy]

AIM

To study blood plasma concentrations of NR2-peptide in patients with ischemic stroke (IS) to assess its diagnostic value as a biomarker of cerebral ischemia and determine the dynamics of the biomarker during treatment with cortexin.

MATERIAL AND METHODS

One hundred and twenty patients, aged from 18 to 70 years, including 36 with transient ischemic attack (TIA) and 84 with IS in the carotid territory (n=70) and vertebral/basilar territory with the Wallenberg-Zakharchenko syndrome (n=14), were enrolled. The National Institute of Health Stroke scale (NIHSS) was used to assess neurological status. Blood plasma concentration of NR2-peptide was measured in all patients at admission and after treatment. All laboratory results were compared with neuroimaging (MRI, CT) data.

RESULTS

Concentrations of NR2-peptide detected in all patients were higher than in controls (>1.5 ng/ml), p<0.0001. The direct correlation between NR2-peptide (from 3.38 ng/ml to 15.6 ng/ml) and ischemic lesion (from few to 80 mm) was observed. A decrease in NR2-peptide concentration (from 8.5 to 5,.9 ng/ml, p<0.0001) was noted in patients treated with cortexin after 10-day treatment course.

CONCLUSION

NR2-peptide blood assay is a reliable hemotest of brain ischemia. Cortexin has a sufficient therapeutic efficacy.

Hypoxia after stroke: a review of experimental and clinical evidence

Background

Hypoxia is a common occurrence following stroke and associated with poor clinical and functional outcomes. Normal oxygen physiology is a finely controlled mechanism from the oxygenation of haemoglobin in the pulmonary capillaries to its dissociation and delivery in the tissues. In no organ is this process more important than the brain, which has a number of vascular adaptions to be able to cope with a certain threshold of hypoxia, beyond which further disruption of oxygen delivery potentially leads to devastating consequences. Hypoxia following stroke is common and is often attributed to pneumonia, aspiration and respiratory muscle dysfunction, with sleep apnoea syndromes, pulmonary embolism and cardiac failure being less common but important treatable causes. As well as treating the underlying cause, oxygen therapy is a vital element to correcting hypoxia, but excessive use can itself cause molecular and clinical harm. As cerebral vascular occlusion completely obliterates oxygen delivery to its target tissue, the use of supplemental oxygen, even when not hypoxic, would seem a reasonable solution to try and correct this deficit, but to date randomised clinical trials have not shown benefit.

Conclusion

Whilst evidence for the use of supplemental oxygen therapy is currently lacking, it is vital to rapidly identify and treat all causes of hypoxia in the acute stroke patient, as a failure to will lead to poorer clinical outcomes. The full results of a large randomised trial looking at the use of supplemental oxygen therapy are currently pending.

CT-angiography source images indicate less fatal outcome despite coma of patients in the Basilar Artery International Cooperation Study

Background

Coma is associated with poor outcome in patients with basilar artery occlusion.

Aims

We sought to assess whether the posterior circulation Acute Stroke Prognosis Early CT Score and the Pons-Midbrain Index applied to CT angiography source images predict the outcome of comatose patients in the Basilar Artery International Cooperation Study.

Methods

Basilar Artery International Cooperation Study was a prospective, observational registry of patients with acute basilar artery occlusion with 48 recruiting centers worldwide. We applied posterior circulation Acute Stroke Prognosis Early CT Score and Pons-Midbrain Index to CT angiography source images of Basilar Artery International Cooperation Study patients who presented with coma. We calculated adjusted risk ratios to assess the association of dichotomized posterior circulation Acute Stroke Prognosis Early CT Score (≥8 vs. <8) and Pons-Midbrain Index (<3 vs. ≥3) with mortality and favourable outcome (modified Rankin Scale score 0–3) at one month.

Results

Of 619 patients in the Basilar Artery International Cooperation Study registry, CT angiography source images were available for review in 158 patients. Among these, 78 patients (49%) presented with coma. Compared to non-comatose patients, comatose patients were more likely to die (risk ratios 2.34; CI 95% 1.56–3.52) and less likely to have a favourable outcome (risk ratios 0.44; CI 95% 0.24–0.80). Among comatose patients, a Pons-Midbrain Index < 3 was related to reduced mortality (adjusted RR 0.66; 95% CI 0.46–0.96), but not to favourable outcome (adjusted RR 1.19; 95% CI 0.39–3.62). Posterior circulation Acute Stroke Prognosis Early CT Score dichotomized at ≥ 8 vs. <8 was not significantly associated with death (adjusted RR 0.70; 95% CI 0.46–1.05).

Conclusion

In comatose patients with basilar artery occlusion, the extent of brainstem ischemia appears to be related to mortality but not to favourable outcome.

Cost-effectiveness and resource use of implementing MRI-guided NACT in ER-positive/HER2-negative breast cancers in The Netherlands

Background

Response-guided neoadjuvant chemotherapy (RG-NACT) with magnetic resonance imaging (MRI) is effective in treating oestrogen receptor positive/human epidermal growth factor receptor-2 negative (ER-positive/HER2-negative) breast cancer. We estimated the expected cost-effectiveness and resources required for its implementation compared to conventional-NACT.

Methods

A Markov model compared costs, quality-adjusted-life-years (QALYs) and costs/QALY of RG-NACT vs. conventional-NACT, from a hospital perspective over a 5-year time horizon. Health services required for and health outcomes of implementation were estimated via resource modelling analysis, considering a current (4 %) and a full (100 %) implementation scenario.

Results

RG-NACT was expected to be more effective and less costly than conventional NACT in both implementation scenarios, with 94 % (current) and 95 % (full) certainty, at a willingness to pay threshold of €20.000/QALY. Fully implementing RG-NACT in the Dutch target population of 6306 patients requires additional 5335 MRI examinations and an (absolute) increase in the number of MRI technologists, by 3.6 fte (full-time equivalent), and of breast radiologists, by 0.4 fte. On the other hand, it prevents 9 additional relapses, 143 cancer deaths, 23 congestive heart failure events and 2 myelodysplastic syndrome/acute myeloid leukaemia events.

Conclusion

Considering cost-effectiveness, RG-NACT is expected to dominate conventional-NACT. While personnel capacity is likely to be sufficient for a full implementation scenario, MRI utilization needs to be intensified.

Multiphase CT Angiography: A New Tool for the Imaging Triage of Patients with Acute Ischemic Stroke

PURPOSE

To describe the use of an imaging selection tool, multiphase computed tomographic (CT) angiography, in patients with acute ischemic stroke (AIS) and to demonstrate its interrater reliability and ability to help determine clinical outcome.

MATERIALS AND METHODS

The local ethics board approved this study. Data are from the pilot phase of PRoveIT, a prospective observational study analyzing utility of multimodal imaging in the triage of patients with AIS. Patients underwent baseline unenhanced CT, single-phase CT angiography of the head and neck, multiphase CT angiography, and perfusion CT. Multiphase CT angiography generates time-resolved images of pial arteries. Pial arterial filling was scored on a six-point ordinal scale, and interrater reliability was tested. Clinical outcomes included a 50% or greater decrease in National Institutes of Health Stroke Scale (NIHSS) over 24 hours and 90-day modified Rankin Scale (mRS) score of 0-2. The ability to predict clinical outcomes was compared between single-phase CT angiography, multiphase CT angiography, and perfusion CT by using receiver operating curve analysis, Akaike information criterion (AIC), and Bayesian information criterion (BIC).

RESULTS

A total of 147 patients were included. Interrater reliability for multiphase CT angiography is excellent (n = 30, κ = 0.81, P < .001). At receiver operating characteristic curve analysis, the ability to predict clinical outcome is modest (C statistic = 0.56, 95% confidence interval [CI]: 0.52, 0.63 for ≥50% decrease in NIHSS over 24 hours; C statistic = 0.6, 95% CI: 0.53, 0.68 for 90-day mRS score of 0-2) but better than that of models using single-phase CT angiography and perfusion CT (P < .05 overall). With AIC and BIC, models that use multiphase CT angiography are better than models that use single-phase CT angiography and perfusion CT for a decrease of 50% or more in NIHSS over 24 hours (AIC = 166, BIC = 171.7; values were lowest for multiphase CT angiography) and a 90-day mRS score of 0-2 (AIC = 132.1, BIC = 137.4; values were lowest for multiphase CT angiography).

CONCLUSION

Multiphase CT angiography is a reliable tool for imaging selection in patients with AIS.

Understanding the pharmacology of stroke and multiple sclerosis through imaging

Stroke and multiple sclerosis (MS) illustrate how clinical imaging can facilitate early phase drug development and most effective medicine use in the clinic. Imaging has enhanced understanding of the dynamics of evolution of disease pathophysiology, better defining treatment targets. Imaging measures can enable stratification of patients for clinical trials and for most cost-effective use in the clinic. In MS, imaging has allowed smaller Phase II clinical trials and contributed to medicine differentiation. It also has led to consideration of suppression of inflammation and neurodegeneration as meaningfully distinct pharmacodynamic concepts. Similar imaging measures can be used in preclinical and clinical studies. Testing translational pharmacological hypotheses using clinical imaging more explicitly could improve the success of the next generation of stroke therapeutics.

CTA collateral status and response to recanalization in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Collateral status at baseline is an independent determinant of clinical outcome among patients with acute ischemic stroke. We sought to identify whether the association between recanalization after intra-arterial acute stroke therapy and favorable clinical response is modified by the presence of good collateral flow assessed on baseline CTA.

MATERIALS AND METHODS

Data are from the Keimyung Stroke Registry, a prospective cohort study of patients with acute ischemic stroke from Daegu, South Korea. Patients with M1 segment MCA with or without intracranial ICA occlusions on baseline CTA from May 2004 to July 2009 who also had baseline MR imaging were included. Two readers blinded to all clinical information assessed baseline and follow-up imaging. Leptomeningeal collaterals on baseline CTA were assessed by consensus by use of the regional leptomeningeal score.

RESULTS

Among 84 patients (mean age, 65.2 ± 13.2 years; median NIHSS score, 14; interquartile range, 8.5), median time from stroke onset to initial MR imaging was 164 minutes. TICI 2b-3 recanalization was achieved in 38.1% of patients and mRS 0-2 at 90 days in 35.8% of patients. In a multivariable model, the interaction between collateral status and recanalization was significant. Only patients with intermediate or good collaterals who recanalized showed a statistically significant association with good clinical outcome (rate ratio = 3.8; 95% CI, 1.2-12.1). Patients with good and intermediate collaterals who did not achieve recanalization and patients with poor collaterals, even if they achieved recanalization, did not do well.

CONCLUSIONS

Patients with good or intermediate collaterals on CTA benefit from intra-arterial therapy, whereas patients with poor collaterals do not benefit from treatment.

Computed Tomography Angiography in the Assessment of Patients With Stroke/TIA

Rapid advance in medical technology has resulted in the availability of numerous tests and treatment strategies in the management of acute stroke. The increasingly evidence-based context of clinical medicine necessitates that clinicians use only appropriate tools to facilitate the diagnostic process and patient management. In this review, we seek to explore the use of computed tomography angiography (CTA) in the diagnosis and management of patients presenting with acute stroke (ischemic and hemorrhagic) or transient ischemic attack (TIA). We present evidence in favor of the use of CTA, highlight the disadvantages of this imaging modality, and present a heuristic model based on our experience at utilizing CTA for decision making in acute stroke and TIAs.

Do silent infarcts modify the effect of thrombolysis for stroke?

OBJECTIVES

Silent brain infarcts (SBI) are a common finding both in stroke-free patients and in patients after a cerebrovascular incident. They are considered a risk factor for subsequent symptomatic strokes. However, their influence on outcome in stroke patients treated with thrombolysis is not established. Our aim was to identify the prevalence of SBI in acute ischaemic stroke patients undergoing routine intravenous thrombolysis and evaluate the association between their presence on pretreatment computed tomography (CT) and outcome.

MATERIAL AND METHODS

We systematically reviewed CT images and clinical records of consecutive patients treated with thrombolysis because of a first-ever stroke between 1 November 2003 and 31 July 2009 in a single stroke centre. We have analysed the frequency of SBI and their influence on outcome.

RESULTS

Silent brain infarcts were present on 82/175 (47%) baseline CT scans. Patients with SBI were significantly older (74 vs 67 years), and more frequently had diabetes (19.5% vs 11.8%) and hyperlipidaemia (37.8% vs 21.5%). There were no significant differences in the ratio of ICH (18.3% vs 14.0%), 3-month mortality (24.7% vs 15.1%) and death or disability (50.6% vs 40.9%), which was also confirmed in a multivariate analysis adjusted for other clinical variables.

CONCLUSIONS

In this study, SBI were not associated with increased risk of ICH nor worse outcome after treatment with rt-PA for stroke. SBI should not be considered an argument against initiating thrombolysis, but further studies are needed to fully understand their association with thrombolysis for stroke.

Protocol for the perfusion and angiography imaging sub-study of the Third International Stroke Trial (IST-3) of alteplase treatment within six-hours of acute ischemic stroke

RATIONALE

Intravenous thrombolysis with recombinant tissue Plasminogen Activator improves outcomes in patients treated early after stroke but at the risk of causing intracranial hemorrhage. Restricting recombinant tissue Plasminogen Activator use to patients with evidence of still salvageable tissue, or with definite arterial occlusion, might help reduce risk, increase benefit and identify patients for treatment at late time windows.

AIMS

To determine if perfusion or angiographic imaging with computed tomography or magnetic resonance help identify patients who are more likely to benefit from recombinant tissue Plasminogen Activator in the context of a large multicenter randomized trial of recombinant tissue Plasminogen Activator given within six-hours of onset of acute ischemic stroke, the Third International Stroke Trial.

DESIGN

Third International Stroke Trial is a prospective multicenter randomized controlled trial testing recombinant tissue Plasminogen Activator (0·9 mg/kg, maximum dose 90 mg) started up to six-hours after onset of acute ischemic stroke, in patients with no clear indication for or contraindication to recombinant tissue Plasminogen Activator. Brain imaging (computed tomography or magnetic resonance) was mandatory pre-randomization to exclude hemorrhage. Scans were read centrally, blinded to treatment and clinical information. In centers where perfusion and/or angiography imaging were used routinely in stroke, these images were also collected centrally, processed and assessed using validated visual scores and computational measures.

STUDY OUTCOMES

The primary outcome in Third International Stroke Trial is alive and independent (Oxford Handicap Score 0-2) at 6 months; secondary outcomes are symptomatic and fatal intracranial hemorrhage, early and late death. The perfusion and angiography study additionally will examine interactions between recombinant tissue Plasminogen Activator and clinical outcomes, infarct growth and recanalization in the presence or absence of perfusion lesions and/or arterial occlusion at presentation. The study is registered ISRCTN25765518.

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

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

Diagnostic potential of the NMDA receptor peptide assay for acute ischemic stroke

BACKGROUND

The acute assessment of patients with suspected ischemic stroke remains challenging. The use of brain biomarker assays may improve the early diagnosis of ischemic stroke. The main goal of the study was to evaluate whether the NR2 peptide, a product of the proteolytic degradation of N-methyl-D-aspartate (NMDA) receptors, can differentiate acute ischemic stroke (IS) from stroke mimics and persons with vascular risk factors/healthy controls. A possible correlation between biomarker values and lesion sizes was investigated as the secondary objective.

METHODS AND FINDINGS

A total of 192 patients with suspected stroke who presented within 72 h of symptom onset were prospectively enrolled. The final diagnosis was determined based on clinical observations and radiological findings. Additionally gender- and age-matched healthy controls (n = 52) and persons with controlled vascular risk factors (n = 48) were recruited to compare NR2 peptide levels. Blinded plasma was assayed by rapid magnetic particles (MP) ELISA for NR2 peptide within 30 min and results for different groups compared using univariate and multivariate statistical analyses. There was a clinical diagnosis of IS in 101 of 192 (53%) and non-stroke in 91 (47%) subjects. The non-stroke group included presented with acute stroke symptoms who had no stroke (n = 71) and stroke mimics (n = 20). The highest NR2 peptide elevations where found in patients with IS that peaked at 12 h following symptom onset. When the biomarker cut off was set at 1.0 ug/L, this resulted in a sensitivity of 92% and a specificity of 96% to detect IS. A moderate correlation (r(s) = 0.73) between NR2 peptide values and acute ischemic cortical lesions (<200 mL) was found.

CONCLUSIONS

This study suggests that the NR2 peptide may be a brain specific biomarker to diagnose acute IS and may allow the differentiation of IS from stroke mimics and controls. Additional larger scale clinical validation studies are required.

Wide variation and rising utilization of stroke magnetic resonance imaging: data from 11 states

OBJECTIVE

Neuroimaging is an essential component of the acute stroke evaluation. Magnetic resonance imaging (MRI) is more accurate than computed tomography (CT) for the diagnosis of stroke, but is more costly and time-consuming. We sought to describe changes in MRI utilization from 1999 to 2008.

METHODS

We performed a serial cross-sectional study with time trends of neuroimaging in patients with a primary International Classification of Diseases, 9th Edition, Clinical Modification discharge diagnosis of stroke admitted through the emergency department in the State Inpatient Databases from 10 states. MRI utilization was measured by Healthcare Cost and Utilization Project criteria. Data were included for states from 1999 to 2008 where MRI utilization could be identified.

RESULTS

A total of 624,842 patients were hospitalized for stroke in the period of interest. MRI utilization increased in all states. Overall, MRI absolute utilization increased 38%, and relative utilization increased 235% (28% of strokes in 1999 to 66% in 2008). Over the same interval, CT utilization changed little (92% in 1999 to 95% in 2008). MRI use varied widely by state. In 2008, MRI utilization ranged from a low of 55% of strokes in Oregon to a high of 79% in Arizona. Diagnostic imaging was the fastest growing component of total hospital costs (213% increase from 1999 to 2007).

INTERPRETATION

MRI utilization during stroke hospitalization increased substantially, with wide geographic variation. Rather than replacing CT, MRI is supplementing it. Consequently, neuroimaging has been the fastest growing component of hospitalization cost in stroke. Recent neuroimaging practices in stroke are not standardized and may represent an opportunity to improve the efficiency of stroke care.

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

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

Extent of hypoattenuation on CT angiography source images in basilar artery occlusion: prognostic value in the Basilar Artery International Cooperation Study

BACKGROUND AND PURPOSE

The posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) quantifies the extent of early ischemic changes in the posterior circulation with a 10-point grading system. We hypothesized that pc-ASPECTS applied to CT angiography source images predicts functional outcome of patients in the Basilar Artery International Cooperation Study (BASICS).

METHODS

BASICS was a prospective, observational registry of consecutive patients with acute symptomatic basilar artery occlusion. Functional outcome was assessed at 1 month. We applied pc-ASPECTS to CT angiography source images of patients with CT angiography for confirmation of basilar artery occlusion. We calculated unadjusted and adjusted risk ratios (RRs) of pc-ASPECTS dichotomized at ≥8 versus <8. Primary outcome measure was favorable outcome (modified Rankin Scale scores 0-3). Secondary outcome measures were mortality and functional independence (modified Rankin Scale scores 0-2).

RESULTS

Of 158 patients included, 78 patients had a CT angiography source images pc-ASPECTS≥8. Patients with a pc-ASPECTS≥8 more often had a favorable outcome than patients with a pc-ASPECTS<8 (crude RR, 1.7; 95% CI, 0.98-3.0). After adjustment for age, baseline National Institutes of Health Stroke Scale score, and thrombolysis, pc-ASPECTS≥8 was not related to favorable outcome (RR, 1.3; 95% CI, 0.8-2.2), but it was related to reduced mortality (RR, 0.7; 95% CI, 0.5-0.98) and functional independence (RR, 2.0; 95% CI, 1.1-3.8). In post hoc analysis, pc-ASPECTS dichotomized at ≥6 versus <6 predicted a favorable outcome (adjusted RR, 3.1; 95% CI, 1.2-7.5).

CONCLUSIONS

pc-ASPECTS on CT angiography source images independently predicted death and functional independence at 1 month in the CT angiography subgroup of patients in the BASICS registry.

Blood biomarkers for the diagnosis of acute cerebrovascular diseases: a prospective cohort study

BACKGROUND

The diagnosis of stroke or TIA in the emergency department is difficult, though important for early treatment. Circulating biomarkers might improve upon clinical assessment at admission.

METHODS

We recruited symptomatic patients with suspected stroke or TIA and drew blood soon after admission. Each patient was assessed with the Face Arm Speech Test (FAST). We measured a panel of 15 circulating inflammatory, thrombotic, cardiac, and cerebral tissue damage biomarkers. Improvement in diagnostic performance was assessed by adding biomarkers to the FAST in logistic regression models to predict a final diagnosis of stroke or TIA (verified by expert review and imaging).

RESULTS

405 patients had suspected stroke: 285 with TIA or stroke (230 definite or probable ischemic stroke, 40 TIA, 15 hemorrhagic stroke) and 120 with other diagnoses. Only the markers t-PA and NT-proBNP were associated positively and significantly (p < 0.01) with a diagnosis of TIA or stroke. The FAST had a sensitivity of 82% (95% CI 78-87) and specificity of 38% (95% CI 29-46) for the diagnosis of TIA or stroke. No biomarker individually improved the sensitivity or specificity of the FAST. A model containing the FAST, age, systolic blood pressure, NT-proBNP and t-PA had a better sensitivity (88%, p < 0.006) and a better specificity (48%, p = 0.04) than the FAST test alone.

CONCLUSIONS

No single blood marker improved the diagnostic performance of a validated clinical stroke scale. Panels of biomarkers may marginally improve diagnosis, but their practicability is uncertain, and requires further study.

Vascular imaging in stroke: comparative analysis

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

Feasibility and safety of magnetic resonance imaging-based thrombolysis in patients with stroke on awakening: initial single-centre experience

BACKGROUND

Up to 25% of all acute ischaemic strokes occur during sleep. Because of the unclear time window, patients with stroke on awakening are usually not considered for acute therapy and excluded from most acute treatment trials.

AIM

To evaluate the feasibility of magnetic resonance imaging-based intravenous thrombolysis in patients with stroke on awakening in a routine clinical setting.

METHODS

Forty-five patients with stroke on awakening clinically qualifying for intravenous thrombolysis and presenting within 6 h after symptom recognition were admitted to our institution between October 2006 and May 2008. Following an institutional protocol, patients received magnetic resonance imaging as a first-line imaging modality and were offered mismatch-based thrombolysis whenever possible. Baseline demographic data, clinical, laboratory and imaging findings were analysed. Outcome was assessed using the modified Rankin Scale score at 3 months.

RESULTS

Magnetic resonance imaging screening was feasible in 43/45 patients (96%). After screening, 10 patients (22%) were treated with intravenous thrombolysis. There were no differences between treated and untreated patients regarding cardiovascular risk factors, stroke aetiology, previous prophylactic treatment and symptom recognition to door time or door to imaging time. Outcome was comparable in both groups despite a trend towards more severe strokes in the intravenous thrombolysis group. Only one asymptomatic and no symptomatic haemorrhage were observed.

CONCLUSION

Our data demonstrate that magnetic resonance imaging-based thrombolysis is feasible and possibly safe in patients with stroke on awakening (SOA). Randomised clinical trials for patients with stroke on awakening are needed to further test the safety and efficacy of intravenous thrombolysis in this patient group. The results of our study may help to initiate and design such studies.

The role of noninvasive techniques in stroke therapy

Noninvasive techniques such as functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) have provided insight into understanding how neural connections are altered in consequence to cerebrovascular injury. The first part of this review will briefly survey some of the methodological issues and limitations related to noninvasive poststroke motor recovery studies. The second section will investigate some of the different neural mechanisms that underlie neurorehabilitation in stroke patients. The third part will explore our current understanding of motor memory processing, describe the neural structures that subserve motor memory consolidation, and discuss the current literature related to memory reconsolidation in healthy adults. Lastly, this paper will suggest the potential therapeutic applications of integrating noninvasive tools with memory consolidation and reconsolidation theories to enhance motor recovery. The overall objective of this work is to demonstrate how noninvasive technologies have been utilized in the multidisciplinary field of clinical behavioral neuroscience and to highlight their potential to be employed as clinical tools to promote individualized motor recovery in stroke patients.

Neuroimaging in acute ischaemic stroke: insights into unanswered questions of pathophysiology

The treatment of acute ischaemic stroke is based on the principle that there is ischaemic but still potentially salvageable tissue that could be rescued if blood flow could be restored quickly. It is assumed that salvage might only be possible in the first few hours, and that infarct expansion is a direct result of failed recanalization of the main artery. This concept arose from experimental work in the 1970s, supported more recently by studies using imaging to identify penumbral tissue. However, although magnetic resonance diffusion and perfusion imaging is a way of imaging penumbral tissue and has been around for over a decade, it is not an easy technique to apply in practice and its use has produced conflicting results. Computed tomography perfusion, and any other tissue perfusion imaging technique, is likely to encounter the same difficulties. Indeed many factors, other than the presence of a diffusion-perfusion mismatch acutely, may determine or influence ultimate tissue fate even days after the stroke, and in turn, clinical outcome. Many of these potential influences are beginning to emerge from studies using different forms of imaging at later times after stroke. This review will explore the information now emerging from imaging studies in large artery ischaemic stroke to summarize knowledge to date and indicate unresolved issues for the future.

Stroke: acute stroke receiving facilities and management

PURPOSE OF REVIEW

Management of ischemic stroke is challenging. No prehospital treatment option exists, and the only approved pharmacologic therapy, that is, systemic thrombolysis, requires brain imaging and initiation of therapy within a narrow therapeutic window. This review provides an overview of recent efforts to optimize management of suspected stroke patients by reducing the interval from symptom onset to reperfusion therapy.

RECENT FINDINGS

There is clear evidence that stroke patients have a favorable outcome when treated with thrombolysis in specialized stroke centers. Data from the European Cooperative Acute Stroke Study-III trial, coupled with improved patient selection by advanced imaging technologies will expand future therapeutic options. However, major obstacles remain in consistently translating scientific advances into clinical practice with only a small percentage of potentially eligible patients receiving thrombolysis. Integrated systems of prehospital management and clinical pathways are necessary to reduce this treatment gap.

SUMMARY

The dogma 'time is brain' is as relevant now as it was at the inauguration of recombinant tissue plasminogen activator for acute stroke treatment in 1996. Knowledge of stroke symptoms and treatment options by the public and first responders, along with integrated stroke systems of care are crucial to ensure rapid access to stroke expertise and treatment.

Magnetic resonance imaging versus computed tomography for detection of acute vascular lesions in patients presenting with stroke symptoms

BACKGROUND

Magnetic resonance imaging (MRI) is increasingly used for the diagnosis of acute ischaemic stroke but its sensitivity for the early detection of intracerebral haemorrhage has been debated. Computed tomography (CT) is extensively used in the clinical management of acute stroke, especially for the rapid exclusion of intracerebral haemorrhage.

OBJECTIVES

To compare the diagnostic accuracy of diffusion-weighted MRI (DWI) and CT for acute ischaemic stroke, and to estimate the diagnostic accuracy of MRI for acute haemorrhagic stroke.

SEARCH STRATEGY

We searched MEDLINE and EMBASE (January 1995 to March 2009) and perused bibliographies of relevant studies for additional references.

SELECTION CRITERIA

We selected studies that either compared DWI and CT in the same patients for detection of ischaemic stroke or examined the utility of MRI for detection of haemorrhagic stroke, had imaging performed within 12 hours of stroke onset, and presented sufficient data to allow construction of contingency tables.

DATA COLLECTION AND ANALYSIS

Three authors independently extracted data on study characteristics and measures of accuracy. We assessed data on ischaemic stroke using random-effects and fixed-effect meta-analyses.

MAIN RESULTS

Eight studies with a total of 308 participants met our inclusion criteria. Seven studies contributed to the assessment of ischaemic stroke and two studies to the assessment of haemorrhagic stroke. The spectrum of patients was relatively narrow in all studies, sample sizes were small, there was substantial incorporation bias, and blinding procedures were often incomplete. Amongst the patients subsequently confirmed to have acute ischaemic stroke (161/226), the summary estimates for DWI were: sensitivity 0.99 (95% CI 0.23 to 1.00), specificity 0.92 (95% CI 0.83 to 0.97). The summary estimates for CT were: sensitivity 0.39 (95% CI 0.16 to 0.69), specificity 1.00 (95% CI 0.94 to 1.00). The two studies on haemorrhagic stroke reported high estimates for diffusion-weighted and gradient-echo sequences but had inconsistent reference standards. We did not calculate overall estimates for these two studies. We were not able to assess practicality or cost-effectiveness issues.

AUTHORS' CONCLUSIONS

DWI appears to be more sensitive than CT for the early detection of ischaemic stroke in highly selected patients. However, the variability in the quality of included studies and the presence of spectrum and incorporation biases render the reliability and generalisability of observed results questionable. Further well-designed studies without methodological biases, in more representative patient samples, with practicality and cost estimates are now needed to determine which patients should undergo MRI and which CT in suspected acute stroke.

Feasibility and logistics of MRI before thrombolytic treatment

OBJECTIVES

The study analyzes feasibility and time-delays in Magnetic resonance imaging (MRI) based thrombolysis and estimate the impact of MRI on individual tissue plasminogen activator (rtPA) treatment.

MATERIALS AND METHODS

Feasibility of MRI and time logistics were prospectively recorded in patients referred with presumed acute stroke over a 2 year time period. Door-to-needle-times (DNT) were compared with those of patients treated with rtPA after conventional CT during the same time period, and to published open label studies.

RESULTS

We received 174 patients with presumed stroke. MRI was feasible in 141 of 161 (88%) of those requiring acute imaging. MRI supported the decision to treat 11 patients with mild symptoms or seizures, and not to treat four patients with extensive infarctions. Median 'door-to-needle time' (DNT) in MR scanned patients (70 min), did not differ significantly from DNT after conventional CT (n = 17, DNT = 66 min, P = 0.27) or the Safe Implementation of Thrombolysis in Stroke (SITS-MOST) registry (DNT = 68 min).

CONCLUSIONS

Magnetic resonance imaging can be performed in the majority of acute stroke patients without delaying treatment. MRI may affect decision making in a large proportion of patients.

A practical assessment of magnetic resonance diffusion-perfusion mismatch in acute stroke: observer variation and outcome

MR diffusion/perfusion mismatch may help identify patients for acute stroke treatment, but mixed results from clinical trials suggest that further evaluation of the mismatch concept is required. To work effectively, mismatch should predict prognosis on arrival at hospital. We assessed mismatch duration and associations with functional outcome in acute stroke. We recruited consecutive patients with acute stroke, recorded baseline clinical variables, performed MR diffusion and perfusion imaging and assessed 3-month functional outcome. We assessed practicalities, agreement between mismatch on mean transit time (MTT) or cerebral blood flow (CBF) maps, visually and with lesion volume, and the relationship of each to functional outcome. Of 82 patients starting imaging, 14 (17%) failed perfusion imaging. Overall, 42% had mismatch (56% at <6 h; 41% at 12-24 h; 23% at 24-48 h). Agreement for mismatch by visual versus volume assessment was fair using MTT (kappa 0.59, 95% CI 0.34-0.84) but poor using CBF (kappa 0.24, 95% CI 0.01-0.48). Mismatch by either definition was not associated with functional outcome, even when the analysis was restricted to just those with mismatch. Visual estimation is a reasonable proxy for mismatch volume on MTT but not CBF. Perfusion is more difficult for acute stroke patients than diffusion imaging. Mismatch is present in many patients beyond 12 h after stroke. Mismatch alone does not distinguish patients with good and poor prognosis; both can do well or poorly. Other factors, e.g. reperfusion, may influence outcome more strongly, even in patients without mismatch.

[Computed tomography in acute ischemic stroke. Current developments compared with stroke MRI]

Modern multimodal acute stroke computed tomography (CT) includes noncontrast cranial CT (NCT), CT angiography (CTA), and CT perfusion imaging (CTP). Compared to stroke MRI, NCT is faster and easier. Multimodal CT can determine acute stroke etiology: Is arterial occlusion or intracerebal hemorrhage present? How extensive are the perfusion disturbance and infarct core, respectively? The information from NCT is sufficient for making acute stroke thrombolysis decisions within 4.5 h from symptom onset. The therapeutic effect of CTA and CTP--as well as acute stroke MRI--on improved functional outcome has still not been established.

Baseline NIH stroke scale responses estimate the probability of each particular stroke subtype

BACKGROUND

Emergency treatment of ischemic stroke should ideally be mechanism specific, but acute subtype diagnosis is problematic. Since different subtypes often are associated with specific patterns of neurological deficits, we hypothesize that scores on baseline NIH stroke scale (NIHSS) items may help emergently stratify patients by their probability of having a particular stroke subtype.

METHODS

We performed multivariate polytomous logistic regression analyses on 1,281 patients enrolled in the Trial of ORG 10172 in Acute Stroke Treatment (TOAST). We tested the predictive value of individual items to the baseline NIHSS exam, and syndromic combinations of those items, in anticipating the TOAST stroke subtype at 3 months adjusting for atrial fibrillation. We then used the most significant NIHSS items to construct a predictive model.

RESULTS

The NIHSS items that discriminate between stroke subtypes are language, neglect, visual field and brachial predominance of weakness. Among patients without atrial fibrillation, a normal score for these 4 variables conveys a 46% chance of lacunar stroke, 12% of atherothrombotic stroke and 10% of cardioembolism. This pattern gradually reverses with increased numbers of abnormal responses. Those with abnormalities in all 4 items have a 0.1% chance of lacunar stroke, 50% of atherothrombotic stroke and 39% of cardioembolism.

CONCLUSIONS

Language, neglect, visual fields and brachial predominance of weakness in the baseline NIHSS help discriminate between subtypes, particularly between lacunar and nonlacunar strokes. Clinical trials testing interventions aimed to particular stroke mechanisms may use these NIHSS items to emergently stratify patients based on their probability of having a particular stroke subtype.

Early changes in physiological variables after stroke

Several aspects of physiology, notably blood pressure, body temperature, blood glucose, and blood oxygen saturation, may be altered after an ischemic stroke and intracerebral hemorrhage. Generally, blood pressure and temperature rise acutely after a stroke, before returning to normal. Blood glucose and oxygen levels may be abnormal in individuals, but they do not follow a set pattern. Several aspects of these physiological alterations remain unclear, including their principal determinants - whether they genuinely affect prognosis (as opposed to merely representing underlying processes such as inflammation or a stress response), whether these effects are adaptive or maladaptive, whether the effects are specific to certain subgroups (e.g. lacunar stroke) and whether modifying physiology also modifies its prognostic effect. Hypertension and hyperglycemia may be helpful or harmful, depending on the perfusion status after an ischemic stroke; the therapeutic response to their lowering may be correspondingly variable. Hypothermia may provide benefits, in addition to preventing harm through protection from hyperthermia. Hypoxia is harmful, but normobaric hyperoxia is unhelpful or even harmful in normoxic patients. Hyperbaric hyperoxia, however, may be beneficial, though this remains unproven. The above-mentioned uncertainties necessitate generally conservative measures for physiology management, although there are notably specific recommendations for thrombolysis-eligible patients. Stroke unit care is associated with better outcome, possibly through better management of poststroke physiology. Stroke units can also facilitate research to clarify the relationship between physiology and prognosis, and to subsequently clarify management guidelines.