Wake-up stroke within 3 hours of symptom awareness: imaging and clinical features compared to standard recombinant tissue plasminogen activator treated stroke

Ischemic stroke with unknown onset of symptoms: current scenario and perspectives for the future

BACKGROUND

Stroke is a major cause of disability worldwide and a neurological emergency. Intravenous thrombolysis and mechanical thrombectomy are effective in the reperfusion of the parenchyma in distress, but the impossibility to determine the exact time of onset was an important cause of exclusion from treatment until a few years ago.

OBJECTIVES

To review the clinical and radiological profile of patients with unknown-onset stroke, the imaging methods to guide the reperfusion treatment, and suggest a protocol for the therapeutic approach.

METHODS

The different imaging methods were grouped according to current evidence-based treatments.

RESULTS

Most studies found no difference between the clinical and imaging characteristics of patients with wake-up stroke and known-onset stroke, suggesting that the ictus, in the first group, occurs just prior to awakening. Regarding the treatment of patients with unknown-onset stroke, four main phase-three trials stand out: WAKE-UP and EXTEND for intravenous thrombolysis, and DAWN and DEFUSE-3 for mechanical thrombectomy. The length of the therapeutic window is based on the diffusion weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch, core-penumbra mismatch, and clinical core mismatch paradigms. The challenges to approach unknown-onset stroke involve extending the length of the time window, the reproducibility of real-world imaging modalities, and the discovery of new methods and therapies for this condition.

CONCLUSION

The advance in the possibilities for the treatment of ischemic stroke, while guided by imaging concepts, has become evident. New studies in this field are essential and needed to structure the health care services for this new scenario.

Endovascular treatment for wake-up stroke and daytime unwitnessed stroke: A meta-analysis

BACKGROUND

Evidence from sources outside the typical clinical research setting, such as a real-world setting, may complement evidence from randomised controlled trials (RCTs). The aim of the present study was to carry out a meta-analysis of available real-world evidence that focused on the efficacy and safety of endovascular treatment in patients with wake-up stroke (WUS) or daytime unwitnessed stroke (DUS) compared to that in patients treated ≤ 6 h after the onset of an ischemic stroke.

METHODS

Data mining was conducted on 1 May 2021 from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials Cochrane Library. The study reviewed all published that assessed the effect of endovascular treatment in WUS and DUS compared to that received by patients with ischemic stroke. Relevant data were extracted and the narrative was reviewed and analysed. The results were expressed as odds ratios (ORs) with 95% confidence intervals (CIs).

FINDINGS

The meta-analysis showed no significant differences between the two groups in the rates of functional independence (OR, 0.81; 95% CI, 0.65-1.02; P = 0.07), symptomatic intracerebral haemorrhage (OR, 0.86; 95% CI, 0.57-1.30; P = 0.470), and all-cause mortality (OR, 0.92; 95% CI, 0.73-1.16; P = 0.50). There was also no heterogeneity between the trials.

CONCLUSION

The pooled analysis provided evidence to support the use of endovascular treatment in WUS and DUS with favourable perfusion imaging. The meta-analysis confirmed the main findings of RCTs of endovascular treatment in WUS and DUS in a real-world setting and therefore strengthens the validity of this treatment strategy.

Efficacy and safety of rt-PA intravenous thrombolysis in patients with wake-up stroke: A meta-analysis

BACKGROUND

: Recombinant tissue plasminogen activator (rt-PA) is one of the most effective therapies for patients with acute ischemic stroke. However, wake-up stroke (WUS) is typically excluded from intravenous thrombolytic therapy because of the unclear time of symptom onset. Therefore, we aimed to assess the efficacy and safety of rt-PA intravenous thrombolysis in patients with WUS by meta-analysis.

METHODS

: We completed a systematic literature search of PubMed, Embase, the Cochrane Library, and SinoMed and included relevant studies of WUS patients covering rt-PA thrombolysis and nonthrombolysis (published from January 1, 2000, to February 28, 2021, with no language restrictions). The primary outcomes included safety outcomes and functional outcomes. Safety outcomes were measured according to the incidence of symptomatic intracranial hemorrhage and mortality within 90 days. The efficacy outcomes were measured based on 90-day modified Rankin Scale scores. We assessed pooled data using either a random-effects model (when P < .10, I2 > 50%) or a fixed-effects model (when P > .10, I2 < 50%).

RESULTS

: A total of 913 patients from 9 studies were included in the meta-analysis. All patients had ischemic stroke confirmed by computed tomography or magnetic resonance imaging. The incidence of modified Rankin Scale 0 to 2 was significantly higher in the rt-PA thrombolysis group compared with the nonthrombolysis group. And rt-PA thrombolytic WUS patients did not differ significantly from nonthrombolytic WUS patients in terms of 90-day mortality. However, the incidence of Symptomatic intracranial hemorrhage was also significantly higher in the rt-PA thrombolysis group than that in the nonthrombolysis group.

CONCLUSIONS

: Patients with WUS who received rt-PA thrombolysis had a significant positive effect within 90 days. In addition, although there was no significant increase in mortality, we need to be aware of the risk of intracranial hemorrhage transformation associated with rt-PA thrombolysis despite no obvious increase in mortality. The safety of rt-PA intravenous thrombolysis should be closely monitored in patients with WUS.

Intravenous thrombolytic treatment and endovascular thrombectomy for ischaemic wake-up stroke

BACKGROUND

About one in five strokes occur during sleep (wake-up stroke). People with wake-up strokes have previously been considered to be ineligible for thrombolytic treatment because the time of stroke onset is unknown. However, recent studies suggest benefit from recanalisation therapies in selected patients.

OBJECTIVES

To assess the effects of intravenous thrombolysis and endovascular thrombectomy versus control in people with acute ischaemic stroke presenting on awakening from sleep.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last search 24 of May 2021). In addition, we searched the following electronic databases in May 2021: Cochrane Central Register of Controlled Trials (CENTRAL; 2021, Issue 4 of 12, April 2021) in the Cochrane Library, MEDLINE, Embase, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform. We searched the Stroke Trials Registry (last search 7 December 2017, as the site is currently inactive). We also screened references lists of relevant trials, contacted trialists, and undertook forward tracking of relevant references.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of intravenous thrombolytic drugs or endovascular thrombectomy treatments in people with acute ischaemic stroke presenting upon awakening.

DATA COLLECTION AND ANALYSIS

Two review authors applied the inclusion criteria, extracted data, and assessed risk of bias and the certainty of the evidence using the GRADE approach. We obtained both published and unpublished data for participants with wake-up strokes. We excluded participants with strokes of unknown onset if the symptoms did not begin upon awakening.

MAIN RESULTS

We included seven trials with a total of 980 participants, of which five trials with 775 participants investigated intravenous thrombolytic treatment and two trials with 205 participants investigated endovascular thrombectomy in large vessel occlusion in the anterior intracranial circulation. All trials used advanced imaging for selecting patients to treat. For intravenous thrombolytic treatment, good functional outcome (defined as modified Rankin Scale score 0 to 2) at 90 days follow-up was observed in 66% of participants randomised to thrombolytic treatment and 58% of participants randomised to control (risk ratio (RR) 1.13, 95% confidence interval (CI) 1.01 to 1.26; P = 0.03; 763 participants, 5 RCTs; high-certainty evidence). Seven per cent of participants randomised to intravenous thrombolytic treatment and 10% of participants randomised to control had died at 90 days follow-up (RR 0.68, 95% CI 0.43 to 1.07; P = 0.09; 763 participants, 5 RCTs; high-certainty evidence). Symptomatic intracranial haemorrhage occurred in 3% of participants randomised to intravenous thrombolytic treatment and 1% of participants randomised to control (RR 3.47, 95% CI 0.98 to 12.26; P = 0.05; 754 participants, 4 RCTs; high-certainty evidence). For endovascular thrombectomy of large vessel occlusion, good functional outcome at 90 days follow-up was observed in 46% of participants randomised to endovascular thrombectomy and 9% of participants randomised to control (RR 5.12, 95% CI 2.57 to 10.17; P < 0.001; 205 participants, 2 RCTs; high-certainty evidence). Twenty-two per cent of participants randomised to endovascular thrombectomy and 33% of participants randomised to control had died at 90 days follow-up (RR 0.68, 95% CI 0.43 to 1.07; P = 0.10; 205 participants, 2 RCTs; high-certainty evidence).

AUTHORS' CONCLUSIONS

In selected patients with acute ischaemic wake-up stroke, both intravenous thrombolytic treatment and endovascular thrombectomy of large vessel occlusion improved functional outcome without increasing the risk of death. However, a possible increased risk of symptomatic intracranial haemorrhage associated with thrombolytic treatment cannot be ruled out. The criteria used for selecting patients to treatment differed between the trials. All studies were relatively small, and six of the seven studies were terminated early. More studies are warranted in order to determine the optimal criteria for selecting patients for treatment.

Estimating nocturnal stroke onset times by magnetic resonance imaging in the WAKE-UP trial

BACKGROUND

Fluid-attenuated inversion recovery (FLAIR) sequences have gained a role to guide treatment of patients with unknown time of stroke symptom onset. Evolution of signal intensities in FLAIR is associated with time since stroke onset with continuous linear increases.

AIMS

Estimating symptom onset during night-sleep in patients from the WAKE-UP trial based on relative signal intensities FLAIR (FLAIR-rSI) from acute stroke lesions an independent dataset (PRE-FLAIR study).

METHODS

FLAIR-rSI was quantified in stroke lesions in PRE-FLAIR and WAKE-UP. The PRE-FLAIR study was a multicenter observational trial establishing FLAIR as a surrogate parameter for time since stroke onset. WAKE-UP was a randomized controlled trial that revealed a benefit for alteplase in patients selected based on a DWI-FLAIR mismatch. Stroke onset times were recorded in PRE-FLAIR and used to fit a linear regression model with FLAIR-rSI, adjusted for patient age and lesion volume. The model was applied to FLAIR-rSI of stroke lesions to estimate onset times in those patients enrolled in WAKE-UP who had symptom onset during night-sleep.

RESULTS

FLAIR-rSI was quantified in 399 patients from PRE-FLAIR. Linear regression indicated a significant association of age (p = 0.001), lesion volume (p = 0.005) and FLAIR-rSI (p < 0.001) with time since symptom onset (adjusted R²= 0.179). In 813 patients from WAKE-UP, distribution of times of last seen well, symptom recognition and MRI examination were recorded. Median times of last seen well were 1 h before midnight (IQR 2.4 h) and symptom recognition 7 h after midnight (IRQ 2.2 h). Based on the FLAIR-rSI profiles, we estimated median stroke onset 6.1 h after midnight (IQR 2.7 h).

CONCLUSION

Nocturnal strokes during night-sleep may predominantly occur during the early morning hours. Our results are in line with evidence of characteristic diurnal patterns of cardiovascular events.

Unknown Onset Stroke: Differences Between Patients with Wake-Up Stroke and Daytime-Unwitnessed Stroke

OBJECTIVES

Patients with unknown onset stroke (UOS) can be categorized as wake-up stroke (WUS) and daytime-unwitnessed stroke (DUS). We sought to determine whether decisions for initial imaging modalities, frequency of mismatch findings, resulting treatment decisions and outcome differ between WUS and DUS patients.

MATERIALS AND METHODS

In a retrospective analysis, all patients with UOS admitted to our Stroke Unit from January to December 2018 were evaluated and classified as either WUS or DUS.

RESULTS

180 patients were included (74.4 % WUS, 25.6 % DUS). Compared to WUS patients, DUS patients received more often a non-contrast computed tomography initially (43.5 % vs. 24.6 %, p = 0.016). MR imaging was performed more frequently in WUS patients (53.7 % vs. 34.8 %, p = 0.027). The rate of mismatch findings in patients examined with either multimodal CT or MRI (126 patients, 101 WUS and 26 DUS) did not differ between the groups. Likewise, the rate of intravenous thrombolysis or mechanical thrombectomy was similar in both groups. DUS patients had more often severe neurological deficits at admission as defined by the National Institutes of Stroke Scale score (14.2 vs. 8.6, p < 0.001).

CONCLUSIONS

Patients with DUS had disadvantages in mismatch-based treatment options due to initial imaging modalities. Current data do not support different treatment concepts in WUS and DUS patients. All UOS patients should initially be evaluated by either multimodal CT or MRI to open a chance to receive reperfusion therapy.

Safety of intravenous thrombolysis in stroke of unknown time of onset: A systematic review and meta-analysis

The safety of intravenous tissue plasminogen activator (IV-tPA) in patients with stroke of unknown time of onset (SUTO) was unclear and mostly concerned. We sought to investigate the safety in terms of symptomatic intracranial hemorrhage (sICH) and death in SUTO patients treated with IV-tPA. We searched PubMed and EMBASE from inception to 2 December 2020 for eligible studies reporting IV-tPA in SUTO patients compared to conservative medical therapy, or to stroke of known onset time (SKOT) treated with IV-tPA within standard time window. We pooled relative risk (RR) with 95% confidence interval (95%CI) with random-effects model. Twenty-four studies were included, enrolling 77,398 patients. SUTO patients with IV-tPA had higher incidence of sICH than that in SUTO patients without IV-tPA (3.8% versus 0.96%; RR = 3.75, 95%CI: 2.69-5.22) but comparable to that in SKOT patients with IV-tPA (3.8% versus 4.1%; RR = 1.16, 95%CI: 0.94-1.44). There was no significant difference in death risk in SUTO patients with IV-tPA versus SUTO patients without IV-tPA (RR = 1.34, 95%CI: 0.60-3.01) and versus SKOT patients with IV-tPA (RR = 1.19, 95%CI: 0.95-1.50). Compared with SUTO patients without IV-tPA, SUTO patients with IV-tPA had higher likelihood of favorable functional outcome (adjusted RR = 1.28, 95%CI: 1.03-1.60) and functional independence (adjusted RR = 1.95, 95%CI: 1.24-3.06), comparable to that in SKOT patients with IV-tPA in favorable functional outcome (adjusted RR = 0.67, 95%CI: 0.38-1.20) and functional independence (adjusted RR = 0.84, 95%CI: 0.59-1.18). SUTO patients could be treated safely and effectively with IV-tPA under the guidance of imaging evaluation.

Clinical efficacy and imaging evaluation of recombinant tissue plasminogen activator thrombolytic therapy in patients with wake up stroke: A randomized controlled trial

INTRODUCTION

Wake up stroke starts in sleep and is a more common form of ischemic stroke. At present, it is still controversial whether wake up stroke can be treated with thrombolytic therapy. Therefore, this study will combine imaging techniques to assess the onset time of wake up stroke patients, and to analyze the imaging characteristics of wake up stroke patients and patients suitable for thrombolytic therapy within the time window.

METHODS/DESIGN

This study will be a single-blinded, randomized controlled trial with 2 parallel groups. It will be conducted at North China University of science and technology affiliated hospital.

DISCUSSION

There is no consistent conclusion about the pathogenesis of wake up stroke. Wake up stroke is more likely to manifest as small vessel disease. The incidence of wake up stroke patients is relatively high, and the effectiveness and safety of intravenous thrombolysis under the guidance of multimode imaging therapy in wake up stroke need to be further explored by prospective, large-scale studies.

TRIAL REGISTRATION

ClinicalTrials.gov, ChiCTR2000034402, Registered on 05 July 2020.

Pathophysiologic mechanisms, neuroimaging and treatment in wake-up stroke

Wake-up stroke (WUS) or ischemic stroke occurring during sleep accounts for 14%-29.6% of all ischemic strokes. Management of WUS is complicated by its narrow therapeutic time window and attributable risk factors, which can affect the safety and efficacy of administering intravenous (IV) tissue plasminogen activator (t-PA). This manuscript will review risk factors of WUS, with a focus on obstructive sleep apnea, potential mechanisms of WUS, and evaluate studies assessing safety and efficacy of IV t-PA treatment in WUS patients guided by neuroimaging to estimate time of symptom onset. The authors used PubMed (1966 to March 2018) to search for the term "Wake-Up Stroke" cross-referenced with "pathophysiology," ''pathogenesis," "pathology," "magnetic resonance imaging," "obstructive sleep apnea," or "treatment." English language Papers were reviewed. Also reviewed were pertinent papers from the reference list of the above-matched manuscripts. Studies that focused only on acute Strokes with known-onset of symptoms were not reviewed. Literature showed several potential risk factors associated with increased risk of WUS. Although the onset of WUS is unknown, a few studies investigated the potential benefit of magnetic resonance imaging (MRI) in estimating the age of onset which encouraged conducting clinical trials assessing the efficacy of MRI-guided thrombolytic therapy in WUS.

Wake-up stroke: imaging-based diagnosis and recanalization therapy

Wake-up stroke (WUS) is a subgroup of ischemic stroke in which patients show no abnormality before sleep while wake up with neurological deficits. In addition to the uncertain onset, WUS patients have difficulty to receive prompt and effective thrombolytic or reperfusion therapy, leading to relatively poor prognosis. A number of researches have indicated that CT or MRI based thrombolysis and endovascular therapy might have benefits for WUS patients. This review article narratively discusses the pathogenesis, risk factors, imaging-based diagnosis and recanalization treatments of WUS with the purpose of expanding current treatment options for this group of stroke patients and exploring better therapeutic methods. The result showed that multimodal MRI or CT scan might be the best methods for extending the time window of WUS and, therefore, a large proportion of WUS patients could have favorable prognosis.

Efficacy and Safety of Thrombolytic Therapy for Stroke with Unknown Time of Onset: A Meta-Analysis of Observational Studies

BACKGROUND

Recombinant tissue plasminogen activator (rt-PA) is one of the most effective therapies available for patients with known-onset stroke (KOS). Whether rt-PA treatment would improve functional outcomes in patients with stroke with unknown time of onset (UTOS) is undetermined, we aimed to systematically assess the efficacy and safety of thrombolysis for UTOS patients in this meta-analysis.

METHODS

A systematic literature search of Medline, Embase, and Cochrane Library was conducted. We considered the relevant data comparing thrombolyzed UTOS patients versus nonthrombolyzed UTOS patients or thrombolyzed UTOS patients versus thrombolyzed KOS patients. Treatment efficacy and safety were measured according to modified Rankin Scale scores of 0-2 (mRS 0-2), and the presence of spontaneous intracerebral hemorrhage (SICH) or mortality at 90 days respectively.

RESULTS

A total of 11 studies with 2581 patients meeting the inclusion criteria were included in the meta-analysis. All the patients had an ischemic lesion that was assessed by imaging including computed tomography or magnetic resonance imaging. Among these studies, 6 compared the thrombolytic efficacy in thrombolyzed UTOS patients with that in nonthrombolyzed UTOS patients (mRS 0-2: odds ratio [OR] =1.76, 95% confidence interval [CI] 1.11-2.81, P = .02), and 8 studies compared thrombolyzed UTOS patients with thrombolyzed KOS patients (mRS 0-2: OR = 0.87, 95% CI 0.66-1.15, P = .33). The incidence of SICH and mortality at 90 days had no difference between thrombolyzed UTOS patients versus nonthrombolyzed UTOS patients and thrombolyzed UTOS patients versus thrombolyzed KOS patients (all P > .05).

CONCLUSIONS

Data from observational studies suggest that thrombolysis for UTOS patients had significantly favorable outcomes at 90 days compared with nonthrombolyzed patients.

Salvianolic Acids for Injection Combined with Conventional Treatment for Patients with Acute Cerebral Infarction: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

This meta-analysis was conducted to evaluate the clinical effectiveness and safety of Salvianolic acids for injection (SAFI) plus conventional treatment (CT) for patients with acute cerebral infarction (ACI) and to assess the evidence to guide clinical practice.

Material/Methods

PubMed, EMBASE, Cochrane Library, Web of Science, and 4 Chinese electronic databases were searched to identify relevant randomized controlled trials (RCTs). The methodological quality of eligible studies was evaluated using the Cochrane risk of bias tool. The reporting quality of eligible studies was evaluated by Consolidated Standards of Reporting Trials (CONSORT) for traditional Chinese medicine. Meta-analysis and evidence quality were performed using RevMan 5.3 and Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

Results

A total of 14 RCTs involving 1309 patients were included. Meta-analysis showed that SAFI plus CT was better than CT alone in improving the total effective rate (RR=1.35, 95% CI 1.25 to 1.44, P<0.00001), reducing the National Institutes of Health Stroke Scale (NIHSS) score (130 mg: WMD=−3.31, 95% CI −3.80 to −2.47, P<0.00001; 100 mg: WMD=−1.91, 95% CI −2.28 to −1.54, P<0.00001), improving the activity of daily living and cognitive function of ACI, and improving the hemorheology (HBV: high shear rate blood viscosity, LBV: low shear rate blood viscosity, PV: plasma viscosity) and C-reactive protein (CRP).

Conclusions

SAFI plus CT in the treatment of ACI can improve the total effective rate, neurological deficit, and ability to perform activities of daily living, and there is no serious adverse reaction. Based on the GRADE system, the evidence quality is low. More large-scale, well-designed, and high-quality RCTs are required to confirm the positive results.

Wake-up stroke: From pathophysiology to management

Wake-up strokes (WUS) are strokes with unknown exact time of onset as they are noted on awakening by the patients. They represent 20% of all ischemic strokes. The chronobiological pattern of ischemic stroke onset, with higher frequency in the first morning hours, is likely to be associated with circadian fluctuations in blood pressure, heart rate, hemostatic processes, and the occurrence of atrial fibrillation episodes. The modulation of stroke onset time also involves the sleep-wake cycle as there is an increased risk associated with rapid-eye-movement sleep. Furthermore, sleep may have an impact on the expression and perception of stroke symptoms by patients, but also on brain tissue ischemia processes via a neuroprotective effect. Obstructive sleep apnea syndrome is particularly prevalent in WUS patients. Until recently, WUS was considered as a contra-indication to reperfusion therapy because of the unknown onset time and the potential cerebral bleeding risk associated with thrombolytic treatment. A renewed interest in WUS has been observed over the past few years related to an improved radiological evaluation of WUS patients and the recent demonstration of the clinical efficacy of reperfusion in selected patients when the presence of salvageable brain tissue on advanced cerebral imaging is demonstrated.

Outcome of multimodal MRI-guided intravenous thrombolysis in patients with stroke with unknown time of onset

Objective

Intravenous tissue plasminogen activator (tPA) is the standard therapy for patients with acute ischaemic stroke (AIS) within 4.5 hours of onset. Recent trials have expanded the endovascular treatment window to 24 hours. We investigated the efficacy and safety of using multimodal MRI to guide intravenous tPA treatment for patients with AIS of unknown time of onset (UTO).

Methods

Data on patients with AIS with UTO and within 4.5 hours of onset were reviewed. Data elements collected and analysed included: demographics, National Institutes of Health Stroke Scale (NIHSS) score at baseline and 2 hours, 24 hours, 7 days after thrombolysis and before discharge, the modified Rankin Scale (mRS) score at 3 months after discharge, imaging findings and any adverse event.

Results

Forty-two patients with UTO and 62 in control group treated within 4.5 hours of onset were treated with intravenous tPA. The NIHSS scores after thrombolysis and/or before discharge in UTO group were significantly improved compared with the baseline (p<0.05). Between the two groups, no significant differences in NIHSS score were observed (p>0.05). Utilising the non-inferiority test, to compare mRS scores (0–2) at 3 months between the two groups, the difference was 5.2% (92% CI, OR 0.196). Patients in the UTO group had mRS scores of 0-2, which were non-inferior to the control group. Their incidence of adverse events was similar.

Conclusions

Utilising multimodal MRI to guide intravenous only thrombolysis for patients with AIS with UTO was safe and effective. In those patients with AIS between 6 and 24 hours of time of onset but without large arterial occlusion, intravenous thrombolysis could be considered an option.

CT-guided thrombolytic treatment of patients with wake-up strokes

Background

Observational studies of thrombolysis outcomes in wake-up acute ischemic stroke patients selected based on non-contrast brain CT criteria suggested that treated patients did as well as or better than those not treated, after adjustment for baseline characteristics. We began offering thrombolytic treatment (IVTPA) to patients presenting with wake-up strokes and normal non-contrast brain CTs, who could be treated within 4.5 h of being found.

Design/methods

A retrospective chart review was performed in patients presenting with AIS between November 2014 and December 2017 who received IVTPA. A planned subgroup analysis compared patients with wake-up strokes and normal non-contrast brain CTs to patients with witnessed stroke treated within 4.5 h of being found, or of witnessed onset, respectively.

Results

Three hundred and six patients were treated, 279 with witnessed-onset and 27 with wake-up strokes. The latter were not candidates for endovascular intervention. Efficacy and safety were similar in both groups. Discharges home, respectively, were 143(53%) and 13(48%); facility discharges were 112(40.1%) and 11(40.7%) and in-hospital mortality was 19 (6.8%) and 3 (11%). Treatment-related symptomatic bleeds were: 5(1.8%) and 1 (3.7%), respectively.

Conclusions

The findings affirm, in a new clinical series reflecting routine practice, that it is safe to treat with IVTPA patients with wake-up strokes and a normal brain CT scan, who are not candidates for endovascular intervention. We hypothesize, that when the non-contrast brain CT scan is normal, it may be safe to extend beyond 4.5 h the IVTPA treatment eligibility window in similar patients with witnessed-onset stroke.

Recanalisation therapies for wake-up stroke

BACKGROUND

About one in five strokes occur during sleep (wake-up stroke). People with wake-up strokes have traditionally been considered ineligible for thrombolytic treatment because the time of stroke onset is unknown. However, some studies suggest that these people may benefit from recanalisation therapies.

OBJECTIVES

To assess the effects of intravenous thrombolysis and other recanalisation therapies versus control in people with acute ischaemic stroke presenting on awakening.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last search: 9 January 2018). In addition, we searched the following electronic databases in December 2017: Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 11) in the Cochrane Library, MEDLINE, Embase, US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), the ISRCTN registry, and Stroke Trials Registry. We also screened references lists of relevant trials, contacted trialists, undertook forward tracking of relevant references, and contacted manufacturers of relevant devices and equipment.

SELECTION CRITERIA

Randomised controlled trials of intravenous thrombolytic drugs or intra-arterial therapies in people with acute ischaemic stroke presenting upon awakening.

DATA COLLECTION AND ANALYSIS

Two review authors applied the inclusion criteria, extracted data, and assessed trial quality and risk of bias using the GRADE approach. We obtained both published and unpublished data.

MAIN RESULTS

We included one pilot trial with nine participants. The trial was a feasibility trial that included participants with an unknown onset of stroke and signs on perfusion computed tomography of ischaemic tissue at risk of infarction, who were randomised to alteplase (0.9 mg/kg) or placebo. One trial was prematurely terminated due to signs of efficacy of the intervention arm; we did not include this trial because we were not able to obtain data for the portion of the participants with wake-up stroke after requesting this information from the trial authors. We identified six ongoing trials.

AUTHORS' CONCLUSIONS

There is insufficient evidence from randomised controlled trials for recommendations concerning recanalisation therapies for wake-up stroke. Results from ongoing trials will hopefully establish the efficacy and safety of such therapies.

Safety of intravenous alteplase within 4.5 hours for patients awakening with stroke symptoms

Background

Up to 25% of acute stroke patients first note symptoms upon awakening. We hypothesized that patients awaking with stroke symptoms may be safely treated with intravenous alteplase (IV tPA) using non-contrast head CT (NCHCT), if they meet all other standard criteria.

Methods

The SAfety of Intravenous thromboLytics in stroke ON awakening (SAIL ON) was a prospective, open-label, single treatment arm, pilot safety trial of standard dose IV tPA in patients who presented with stroke symptoms within 0–4.5 hours of awakening. From January 30, 2013, to September 1, 2015, twenty consecutive wakeup stroke patients selected by NCHCT were enrolled. The primary outcome was symptomatic intracerebral hemorrhage (sICH) in the first 36 hours. Secondary outcomes included NIH stroke scale (NIHSS) at 24 hours; and modified Rankin Score (mRS), NIHSS, and Barthel index at 90 days.

Results

The average age was 65 years (range 47–83); 40% were women; 50% were African American. The average NIHSS was 6 (range 4–11). The average time from wake-up to IV tPA was 205 minutes (range 114–270). The average time from last known well to IV tPA was 580 minutes (range 353–876). The median mRS at 90 days was 1 (range 0–5). No patients had sICH; two of 20 (10%) had asymptomatic ICH on routine post IV tPA brain imaging.

Conclusions

Administration of IV tPA was feasible and may be safe in wakeup stroke patients presenting within 4.5 hours from awakening, screened with NCHCT. An adequately powered randomized clinical trial is needed.

Clinical trial registration

ClinicalTrials.gov NCT01643902.

Wake-Up Stroke versus Stroke with Known Onset Time: Clinical and Multimodality CT Imaging Characteristics

BACKGROUND

Current guidelines for the treatment of acute ischemic stroke are mainly based on the time between symptom onset and initiation of treatment. This time is unknown in patients with wake-up stroke (WUS). We investigated clinical and multimodality CT imaging characteristics on admission in patients with WUS and in patients with a stroke with a known onset time.

METHODS

All patients were selected from a large prospective cohort study (Dutch acute stroke study). WUS patients last seen well > 4.5 and ≤4.5 h were separately compared to patients with a known onset time ≤4.5 h. In addition, WUS patients with a proximal occlusion of the anterior circulation last seen well > 6 and ≤6 h were separately compared to patients with a known onset time ≤6 h and a proximal occlusion. National Institute of Health Stroke Score, age, gender, history of atrial fibrillation, non-contrast CT (NCCT) Alberta Stroke Program Early CT Score (ASPECTS), CT-perfusion abnormalities, proximal occlusions, and collateral filling on CT angiography were compared between groups using the Mann-Whitney U test and Fisher's exact test.

RESULTS

WUS occurred in 149/1,393 (10.7%) patients. Admission clinical and imaging characteristics of WUS patients last seen well > 4.5 h (n = 81) were not different from WUS patients last seen well ≤4.5 h (n = 68). Although WUS patients last seen well > 4.5 h had a significantly lower NCCT ASPECTS than patients with a known time of stroke symptom onset of ≤4.5 h (n = 1,026), 85.2% had an NCCT ASPECTS > 7 and 75% had a combination of favorable ASPECTS > 7 and good collateral filling. There were no statistically significant differences between the admission clinical and imaging characteristics of WUS patients with proximal occlusions last seen well > 6 h (n = 23), last seen well ≤6 h (n = 40), and patients with a known time to stroke symptom onset ≤6 h (n = 399). Of all WUS patients with proximal occlusions last seen well > 6 h, only 4.3% had severe ischemia (ASPECTS < 5), 13 (56.5%) had ASPECTS > 7 and good collateral filling.

CONCLUSIONS

There are only minor differences between clinical and imaging characteristics of WUS patients and patients who arrive in the hospital within the time criteria for intravenous or endovascular treatment. Therefore, CT imaging may help to identify WUS patients who would benefit from treatment and rule out those patients with severe ischemia and poor collaterals.

Neuroimaging Paradigms to Identify Patients for Reperfusion Therapy in Stroke of Unknown Onset

Despite the proven efficacy of intravenous alteplase or endovascular thrombectomy for the treatment of patients with acute ischemic stroke, only a minority receive these treatments. This low treatment rate is due in large part to delay in hospital arrival or uncertainty as to the exact time of onset of ischemic stroke, which renders patients outside the current guideline-recommended window of eligibility for receiving these therapeutics. However, recent pivotal clinical trials of late-window thrombectomy now force us to rethink the value of a simplistic chronological formulation that “time is brain.” We must recognize a more nuanced concept that the rate of tissue death as a function of time is not invariant, that still salvageable tissue at risk of infarction may be present up to 24 h after last-known well, and that those patients may strongly benefit from reperfusion. Multiple studies have sought to address this clinical dilemma using neuroimaging methods to identify a radiographic time-stamp of stroke onset or evidence of salvageable ischemic tissue and thereby increase the number of patients eligible for reperfusion therapies. In this review, we provide a critical analysis of the current state of neuroimaging techniques to select patients with unwitnessed stroke for revascularization therapies and speculate on the future direction of this clinically relevant area of stroke research.

Safety and cost-effectiveness thrombolysis by diffusion-weighted imaging and fluid attenuated inversion recovery mismatch for wake-up stroke

Wake-up stroke, defined as patients who wake up with stroke symptoms which were not present prior to falling asleep, accounted for 14%-25% of acute ischemic stroke. Due to the unknown time of symptom onset, wake-up stoke was not in including criteria of intravenous thrombolysis. Several large randomized stroke trials using diffusion-weighted imaging(DWI)and fluid attenuated inversion recovery(FLAIR)mismatch patient selection may identify a subset of patients with wake-up stroke that can safely and effectively benefit from intravenous thrombolysis. In addition, economic factor was another important limitation to generalize thrombolysis treatment. Fortunately, MRI-based thrombolysis was a cost-effective treatment for wake-up stroke compared to these patients with no thrombolysis.

Unknown onset ischemic strokes in patients last-seen-well >4.5 h: differences between wake-up and daytime-unwitnessed strokes

Patients with unknown time of stroke onset (UOS) represent around one-third of ischemic stroke patients. These are patients with wake-up stroke (WUS) or daytime-unwitnessed stroke (DUS), often presenting outside the time-window for reperfusion therapy. UOS patients presenting between 4.5 and 12 h after time of last-seen-well were included. Clinical and imaging characteristics were compared between WUS and DUS patients. Good functional outcome was defined as a modified Rankin scale of ≤2 at follow-up. Sixty-one UOS patients were included: 42 WUS and 19 DUS patients. Stroke severity at presentation was mild to moderate with a median National Institutes of Health Stroke Scale of 5 in WUS and 6 in DUS patients. Time between last-seen-well and presentation at the hospital was shorter in patients with DUS compared to WUS (506 vs 362 min, p < 0.01). CT imaging results were similar, with a median Alberta Stroke Program Early CT Score of 10 for both WUS and DUS patients. After correction for age and NIHSS at presentation, no difference in good functional outcome was found between WUS (52%) and DUS (22%). In patients with unknown onset ischemic strokes presenting between 4.5 and 12 h after time of last-seen-well, clinical and radiological features were in large part similar between WUS and DUS. The outcome in the overall cohort was rather poor despite a favorable neuroimaging profile at presentation. These findings underscore the need for clinical trials in patients in whom stroke onset time is unknown.

The Relationship between Functional Outcome and Prehospital Time Interval in Patients with Cerebral Infarction

BACKGROUND

When symptoms of cerebral infarction are recognized in a patient, he or she should be transported to a hospital and should be started on the appropriate treatments. The effectiveness of delayed treatment of cerebral infarction with respect to the initial diagnosis or perception of the disease is still unclear.

METHODS

We retrospectively investigated whether the functional outcomes would improve if patients with cerebral infarction were transported to the hospital with minimum delay. One-hundred twenty-two patients who were transported to Mishuku Hospital from January 2012 to August 2015 were included. We conducted multiple regression analyses. The criterion variable included the BI at discharge, and the explanatory variables were age, sex, days of hospital stay, the Barthel Index (BI) on admission, time from symptom onset to hospital arrival, time from emergency medical service perception to hospital arrival, recombinant tissue plasminogen activator (rt-PA) treatment, and the occluded artery type.

RESULTS

In all 122 cases, the BI at the time of discharge was not related to onset time (P = .453) but was significantly related to perception time (P = .026). BI scores at discharge were high for young patients (P = .002) and for patients with short hospital stays (P <.001). In the rt-PA group (52 cases), BI scores at discharge were also high when the perception time was short (P = .036).

CONCLUSIONS

A short interval between perception and hospital arrival improves the functional outcomes for patients with cerebral infarction. Thus, patients with cerebral infarctions must be treated with minimal delay after diagnosis of the condition.

Wake-up stroke-Amendable for thrombolysis-like stroke with known onset time?

Patients suffering an acute ischemic stroke can be treated with intravenous thrombolysis in the absence of contraindications. A known onset time is a prerequisite as treatment, according to guidelines, has to be started within 4.5 hours. In patients awakening with a stroke, the last time they were seen without a neurological deficit is assumed to be the time of onset. Thus, despite of lack of contraindications on initial brain imaging, these patients are largely excluded from therapy. This review discusses the underlying pathophysiological, clinical, and radiological evidence surrounding wake-up stroke and its consequences for making treatment decisions.

Intravenous Tissue Plasminogen Activator for Wake-Up Stroke: A Propensity Score-Matched Analysis

GOAL

To evaluate the safety and efficacy of intravenous (IV) tissue plasminogen activator (tPA) in the treatment of wake-up stroke (WUS) using propensity score (PS) analysis.

MATERIALS AND METHODS

Consecutive acute ischemic stroke patients meeting inclusion criteria were retrospectively identified from our stroke registry between July 2008 and May 2014, and classified as stroke onset less than or equal to 4.5 hours treated with tPA (control; n = 369), tPA-treated WUS (n = 46), or nontreated WUS (n = 154). The primary outcome of interest for safety was symptomatic intracerebral hemorrhage (sICH), defined as parenchymal hemorrhage associated with a greater than or equal to 4-point increase in National Institutes of Health Stroke Scale (NIHSS) score. Multivariate logistic regression with adjustment for confounders and PS for receiving IV tPA assessed outcomes, along with PS-matched average treatment effect on the treated (ATT).

FINDINGS

No significant difference was found in rates of sICH between tPA-treated WUS, nontreated WUS, and controls (2.2%, .7%, and 3%, respectively), or in the odds of sICH between tPA-treated WUS and controls (OR = .53, 95% CI = .06-4.60, P = .568). Among WUS patients, tPA treatment was significantly associated with higher odds of good functional outcome in fully adjusted analyses (OR = 7.22, 95% CI = 2.28-22.88, P = .001). The ATT of tPA for WUS patients demonstrated a significantly greater decrease in NIHSS score at discharge when compared to nontreated WUS patients (-4.32 versus -.34, P = .032).

CONCLUSIONS

Comparable rates of sICH between treated WUS and stroke onset less than or equal to 4.5 hours treated with tPA suggest that tPA may be safely used to treat WUS. Superior outcomes for tPA-treated versus nontreated WUS subjects may suggest clinical efficacy of the treatment.

Neurological Fallacies Leading to Malpractice: A Case Studies Approach

A young woman presents with an intracranial arachnoid cyst. Another is diagnosed with migraine headache. An elderly man awakens with a stroke. And a baby delivered vaginally after 2 hours of questionable electronic fetal monitoring patterns grows up to have cerebral palsy. These seemingly disparate cases share a common underlying theme: medical myths. Myths that may lead not only to misdiagnosis and treatment harms but to seemingly never-ending medical malpractice lawsuits, potentially culminating in a settlement or judgment against an unsuspecting neurologist. This article provides a case studies approach exposing the fallacies and highlighting proper management of these common neurologic presentations.

A Stroke Registry Data on the Use of Intravenous Recombinant Tissue Plasminogen Activator in Stroke of Unknown Time of Onset

BACKGROUND

Stroke of unknown time of onset (SUTO) constitutes one fifth of all ischemic stroke admissions, and routine use of intravenous recombinant tissue plasminogen activator (IV rtPA) is recommended only in patients with a symptom onset time of less than 4.5 hours. There are limited data on clinical outcome in patients with SUTO versus patients with symptoms onset less than 4.5 hours from onset time. We hypothesized that efficacy and safety outcomes of IV rtPA therapy in selected SUTO patients are comparable to those with known onset time.

METHODS

We compared 90 days' modified Rankin Scale (mRS), rates of symptomatic intracerebral hemorrhage (sICH), in-hospital mortality, and death due to sICH between 3 groups treated with IV rtPA: SUTO, 3 hours or less, and 3.0-4.5 hours from prospective patient admissions between April 1, 2012, and July 31, 2013.

RESULTS

There were 65 participants in the SUTO group, 186 in the 3 hours or less group, and 51 in the 3.0-4.5 hours group. In-hospital mortality rates were 14.5%, 13.5%, and 11.8%, respectively. sICH risks were 1.5%, 1.6%, and 5.8%, and death rates due to sICH were 0%, 1.1%, and 1.9%, respectively. Ninety days' odds of excellent clinical outcome (mRS score 0-1) were not different between the SUTO group (odds ratio [OR] 1.14, 95% confidence interval [CI]: .63-2.10), the 3 hours or less group (OR .87, 95% CI: .48-1.60), and the 3.0-4.5 hours group (OR .79, 95% CI: .48-1.60) (P = .82).

CONCLUSION

Thrombolytic therapy outcome in SUTO is not different from in-license use in our patient population. There is an urgent need to include this patient group in ongoing randomized multicenter trials.

Wake-up stroke: Dawn of a new era

Wake-up stroke or stroke with unclear onset of symptoms is known to occur in one-fourth of ischemic stroke patients. These patients are not considered for thrombolytic therapy based on time designation of their symptom onset as per the current guidelines. Observational studies have investigated the pathophysiology and suggested actual onset of symptoms to be approximate to the awakening time for these patients. Use of advanced imaging modalities in these patients tends to identify favorable patient profiles for thrombolysis. Results of the ongoing trials will likely beckon a seminal juncture in stroke therapy and deliver critical modifications in the current treatment guidelines for thrombolysis in this substantial, yet neglected, group of stroke patients. In this article, we have reviewed the predisposing factors, preferred imaging modalities and various ongoing thrombolytic and endovascular trials to date for patients with unclear time of symptom onset or who wake up with stroke symptoms.

International Survey on the Management of Wake-Up Stroke

Background

Patients who wake up having experienced a stroke while asleep represent around 20% of acute stroke admissions. According to international guidelines for the management of acute stroke, patients presenting with wake-up stroke are not currently eligible to receive revascularization treatments. In this study, we aimed to assess the opinions of stroke experts about the management of patients with wake-up stroke by using an international multicenter electronic survey.

Method

This study consisted of 8 questions on wake-up stroke treatment.

Results

Two hundred invitations to participate in the survey were sent by e-mail. Fifty-nine participants started the survey, 4 dropped out before completing it, and 55 completed the full questionnaire. We had 55 participants from 22 countries.

Conclusions

In this study, most stroke experts recommended a recanalization treatment for wake-up stroke. However, there was considerable disagreement among experts regarding the best brain imaging method and the best recanalization treatment. The results of ongoing randomized trials on wake-up stroke are urgently needed.

Brain imaging in acute ischemic stroke—MRI or CT?

In acute stroke, imaging provides different technologies to demonstrate stroke subtype, tissue perfusion and vessel patency. In this review, we highlight recent clinical studies that are likely to guide therapeutic decisions. Clot length in computed tomography (CT) and clot burden in MR, imaging of leptomeningeal collaterals and indicators for active bleeding are illustrated. Imaging-based concepts for treatment of stroke at awakening and pre-hospital treatment in specialized ambulances offer new potentials to improve patient outcome.

What to do With Wake-Up Stroke

Wake-up stroke, defined as the situation where a patient awakens with stroke symptoms that were not present prior to falling asleep, represents roughly 1 in 5 acute ischemic strokes and remains a therapeutic dilemma. Patients with wake-up stroke were excluded from most ischemic stroke treatment trials and are often not eligible for acute reperfusion therapy in clinical practice, leading to poor outcomes. Studies of neuroimaging with standard noncontrast computed tomography (CT), magnetic resonance imaging (MRI), and multimodal perfusion-based CT and MRI suggest wake-up stroke may occur shortly before awakening and may assist in selecting patients for acute reperfusion therapies. Pilot studies of wake-up stroke treatment based on these neuroimaging features are promising but have limited generalizability. Ongoing randomized treatment trials using neuroimaging-based patient selection may identify a subset of patients with wake-up stroke that can safely benefit from acute reperfusion therapies.

IV thrombolysis for treatment of patients with stroke upon awakening: Yes? No?

Current guidelines recommend IV administration of recombinant tissue plasminogen activator (rtPA) to carefully selected patients who can be treated within 4.5 hours of ischemic stroke onset. Patients whose neurologic symptoms are discovered upon awakening (wake-up stroke) generally are not given rtPA because of the uncertainty about the time of stroke onset. This group of patients may be relatively large. Preliminary reports suggest that patients with wake-up stroke who can be treated within 4.5 hours of discovery may respond similarly to patients with an established time of stroke onset. Clinical trials, which are selecting patients to treat primarily based on imaging surrogates, are under way. Pending the results of these trials, data about the utility of clinical or imaging findings that would identify those patients who could be treated and information about the safety and efficacy of IV rtPA in this situation are not available.

Efficacy and safety of thrombolysis for stroke of unknown onset time: a meta-analysis

Current stroke treatment guidelines exclude unknown onset stroke (UOS) patients from thrombolytic therapy even though several studies have reported significant treatment efficacy and safety. We performed a meta-analysis of relevant studies retrieved by systematic searches of the PubMed, Embase, and Cochrane databases up to December 31, 2013. Dichotomized modified Rankin Scale (mRS) scores 0-1 at 90 days, mRS 0-2 at 90 days, overall mortality, and symptomatic intracranial hemorrhage (sICH) incidence were collected as primary outcome measures. Fixed effects meta-analytical models were used, and between-study heterogeneity was assessed. Eleven studies encompassing 1,832 patients were included. In case-control studies of UOS patients, thrombolysis was associated with a significant increase in the proportion of patients with mRS scores of 0-1 (OR 2.37; 95% CI 1.20-4.69; P = 0.013) and 0-2 (OR 2.03; 95% CI 1.26-3.30; P = 0.004) without increased mortality or sICH incidence. In studies comparing thrombolysis-treated UOS to thrombolysis-treated known onset stroke, however, fewer UOS patients had mRS scores of 0-1 (OR 0.70; 95% CI 0.51-0.97; P = 0.033) with no change in mortality, sICH incidence, or patients with mRS of 0-2. Subgroup analysis based on imaging criteria and time window of thrombolysis indicated that UOS patients treated within 3 h after first found abnormal and those with early ischemic changes restricted to <1/3 of the middle cerebral artery territory gained more benefit from thrombolysis treatment than the whole UOS population. Randomized controlled trials are warranted to confirm the efficacy of thrombolysis in this UOS subgroup.

Acute stroke imaging: feasibility and value of MR angiography with high spatial and temporal resolution for vessel assessment and perfusion analysis in patients with wake-up stroke

RATIONALE AND OBJECTIVES

Magnetic resonance (MR) imaging (MRI) provides information that can be used to estimate the symptom onset in patients with wake-up stroke (WUS). Time-resolved MR angiography (MRA) is the fastest available MR sequence technique for vessel assessment, and the different phases acquired can provide information about cerebral perfusion. The aim of this study was to evaluate the diagnostic performance of time-resolved MRA both for the assessment of vessel morphology and for the feasibility of perfusion.

MATERIALS AND METHODS

Nineteen patients with WUS were included. Image quality and vessel pathologies were evaluated and correlated to time-of-flight-MRA (n = 14), computed tomography-angiography (n = 4), sonography (n = 12), and conventional angiography (n = 6). The temporal delay of signal enhancement in all pixels of the time-resolved MRA measurement after contrast injection was evaluated and compared to dynamic susceptibility contrast-enhanced (DSC) perfusion imaging (n = 13).

RESULTS

Time-resolved MRA resulted in the diagnosis of large vessel disease in 14 of 19 patients, involving the internal carotids (n = 4), the vertebral arteries (n = 3), and the circle of Willis (n = 10). All severe vascular pathologies which influence patients' acute stroke therapy were obtained by time-resolved MRA. Overestimation of stenoses in two of 14 patients resulted in sensitivity and specificity of 100% and 71%, respectively. Time-to-peak (TTP) estimations were hampered by movement artifacts in four patients (31%). Compared to DSC, the area of TTP delay was comparable in size and localization without relevant overestimation or underestimation.

CONCLUSIONS

Time-resolved MRA is a valuable technique in patients with WUS with high sensitivity and high negative predictive value. Cerebral perfusion estimation can be performed in selected cases for therapy decision but can be hampered by patient movement.

Wake-up stroke: clinical characteristics, imaging findings, and treatment option - an update

About 25% of all strokes occur during sleep, i.e., without knowledge of exact time of symptom onset. According to licensing criteria, this large group of patients is excluded from treatment with received tissue-plasminogen activator, the only specific stroke treatment proven effective in large randomized trials. This paper reviews clinical and imaging characteristics of wake-up stroke and gives an update on treatment options for these patients. From clinical and imaging studies, there is evidence suggesting that many wake-up strokes occur close to awakening and thus, patients might be within the approved time-window of thrombolysis when presenting to the emergency department. Several imaging approaches are suggested to identify wake-up stroke patients likely to benefit from thrombolysis, including non-contrast CT, CT-perfusion, penumbral MRI, and the recent concept of diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR). A number of small case series and observational studies report results of thrombolysis in wake-up stroke, and no safety concerns have occurred, while conclusions on efficacy cannot be drawn from these studies. To this end, there are ongoing clinical trials enrolling wake-up stroke patients based on imaging findings, i.e., the DWI-FLAIR-mismatch (WAKE-UP) or penumbral imaging (EXTEND). The results of these trials will provide evidence to guide thrombolysis in wake-up stroke and thus, expand treatment options for this large group of stroke patients.

Diffusion-weighted image and fluid-attenuated inversion recovery image mismatch: unclear-onset versus clear-onset stroke

BACKGROUND AND PURPOSE

Mismatch in lesion visibility between diffusion-weighted image and fluid-attenuated inversion recovery image (DWI-FLAIR mismatch) has been proposed as a biomarker for the estimation of ischemic lesion age. The actual onset in some patients with unclear-onset stroke (UnCOS) may be close to the first-found abnormal time. We hypothesized that patients with UnCOS within a particular time window might have a similar DWI-FLAIR mismatch profile with patients with clear-onset stroke (COS).

METHODS

Patients who underwent MRI within 6 hours from first-found abnormal time were recruited retrospectively. Clinical characteristics and the proportion of DWI-FLAIR and perfusion-weighted image-DWI mismatch in each time window were compared between UnCOS and COS.

RESULTS

The final analysis included 259 patients (114 with UnCOS and 145 with COS). Patients with UnCOS were older and had more severe stroke at baseline. Risk factors, stroke subtypes, and perfusion-weighted image-DWI mismatch did not differ between the 2 groups. The proportion of patients with DWI-FLAIR mismatch in UnCOS did not differ from COS within 2 hours of first-found abnormal time (50.0% versus 51.5%; P=0.92), but it was significantly lower in UnCOS than in COS at 2 to 3 hours (16.1% versus 44.4%; P=0.02), 3 to 4 hours (13.8% versus 36.4%; P=0.04), and 4 to 5 hours (5.6% versus 29.6%; P=0.05).

CONCLUSIONS

The proportion of DWI-FLAIR mismatch in UnCOS within the first 2 hours from first-found abnormal time was similar with COS, but it sharply decreased beyond 2 hours. These data suggest that patients with UnCOS within 2 hours of symptom detection may be good candidates for multimodal imaging-based thrombolysis.

Negative fluid-attenuated inversion recovery-based intravenous thrombolysis using recombinant tissue plasminogen activator in acute stroke patients with unknown onset time

BACKGROUND

Approximately 25% of acute stroke patients were excluded from intravenous thrombolysis using recombinant tissue plasminogen activator (IV-tPA) because of unknown onset time. Recent studies have shown that patients with unknown onset time would be able to receive IV-tPA when showing no ischemia on fluid-attenuated inversion recovery (negative FLAIR). The present study evaluated the safety and feasibility of IV-tPA in patients with unknown onset time and negative FLAIR compared to those with standard IV-tPA.

METHODS

Stroke patients with unknown onset time were prospectively enrolled. Only patients with an occlusion of the internal carotid artery (ICA) and/or middle cerebral artery (M1 and M2) with a Diffusion-Weighted Imaging-Alberta Stroke Program Early CT Score (DWI-ASPECTS) ≥5 were analyzed. IV-tPA was performed within 3 h from the 'first found abnormal time' if the patient showed negative FLAIR. Standard IV-tPA patients were extracted from our registry as controls after having been matched by age and occluded artery to the negative FLAIR (N-F) group.

RESULTS

Twenty patients in the N-F group and 60 in the control group were included. National Institutes of Health Stroke Scale (NIHSS) scores [median 18 (interquartile range 13-20) vs. 17 (12-20), p = 0.609] and DWI-ASPECTS [9 (7-9) vs. 8 (5-9), p = 0.213] were similar between the 2 groups. ICA occlusion was seen in 35%, M1 in 50%, and M2 in 15% in both groups. None of the N-F group and 1 (2%) of the control group experienced symptomatic intracerebral hemorrhage (p = 1.000). Recanalization within 1 h after IV-tPA was achieved in 6 (30%) patients in the N-F group and 24 (40%) in the control group (p = 0.595). Recanalization at 24 h after IV-tPA was seen in 13 (65%) patients in the N-F group and 43 (72%) in the control group (p = 0.584). At 7 days, 8 (40%) in the N-F group and 28 (47%) in the control group had a dramatic recovery (defined as a ≥10-point reduction in the total NIHSS score or a score of 0 or 1) (p = 0.796). At 3 months, a favorable outcome (modified Rankin scale score, 0-2) was seen in 47% in the N-F group and 33% in the control group (p = 0.365).

CONCLUSION

IV-tPA in negative FLAIR patients with unknown onset time appears safe and feasible.

Human embryonic stem cells: the real challenge for research as well as for bioethics is still ahead of us

Research on human embryonic stem cells (ESCs) has aroused a lot of controversy for years. Stimulated by recent work on mammalian embryology and new developments in stem cell research, an International Symposium entitled 'Stem Cell Research: A Challenge for Embryology, Regenerative Medicine and Bioethics' was held in Bonn (Germany) in 2006, bringing together embryologists, stem cell researchers and ethicists interested in human ESC research and the ensuing ethical debate. Two contributions to this Symposium are being published in Cells Tissues Organs, and the present paper aims to provide an introduction to these as well as personal impressions of the author about the perspectives that surfaced at the meeting, confronting them with relevant reports about stem cell research published recently. This paper highlights discussions about the mechanisms of specification of the main body axes during development, the role of extrinsic or intrinsic signals, and about the remarkable potential of ESCs to develop a basic body plan (individuation capacity) resembling properties of early embryonic cells (as shown by the formation of embryoid bodies and entire embryos if tetraploid complementation is performed). Another topic is 'alternative sources for human ESCs' recently proposed by the US President's Council on Bioethics ('organismically dead embryos', biopsied blastomeres or 'biological artifacts', e.g. created by 'altered nuclear transfer' and reprogramming of somatic cells). The possibility to rescue such (epi)genetically handicapped cells shows that this is not a way leading out of the ethical cul-de-sac. Recent reports about reprogramming somatic cells (fibroblasts) to gain ES-like potential highlight again the importance of focusing on the developmental potentiality as the major challenge for ethical considerations. Such a change of focus may be the only way out of the ethical impasse.