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

Computed tomography hypoperfusion-hypodensity mismatch vs. automated perfusion mismatch to identify stroke patients eligible for thrombolysis

Background and purpose

Automated perfusion imaging can detect stroke patients with unknown time of symptom onset who are eligible for thrombolysis. However, the availability of this technique is limited. We, therefore, established the novel concept of computed tomography (CT) hypoperfusion-hypodensity mismatch, i.e., an ischemic core lesion visible on cerebral perfusion CT without visible hypodensity in the corresponding native cerebral CT. We compared both methods regarding their accuracy in identifying patients suitable for thrombolysis.

Methods

In a retrospective analysis of the MissPerfeCT observational cohort study, patients were classified as suitable or not for thrombolysis based on established time window and imaging criteria. We calculated predictive values for hypoperfusion-hypodensity mismatch and automated perfusion imaging to compare accuracy in the identification of patients suitable for thrombolysis.

Results

Of 247 patients, 219 (88.7%) were eligible for thrombolysis and 28 (11.3%) were not eligible for thrombolysis. Of 197 patients who were within 4.5 h of symptom onset, 190 (96.4%) were identified by hypoperfusion-hypodensity mismatch and 88 (44.7%) by automated perfusion mismatch (p < 0.001). Of 22 patients who were beyond 4.5 h of symptom onset but were eligible for thrombolysis, 5 patients (22.7%) were identified by hypoperfusion-hypodensity mismatch. Predictive values for the hypoperfusion-hypodensity mismatch vs. automated perfusion mismatch were as follows: sensitivity, 89.0% vs. 50.2%; specificity, 71.4% vs. 100.0%; positive predictive value, 96.1% vs. 100.0%; and negative predictive value, 45.5% vs. 20.4%.

Conclusion

The novel method of hypoperfusion-hypodensity mismatch can identify patients suitable for thrombolysis with higher sensitivity and lower specificity than established techniques. Using this simple method might therefore increase the proportion of patients treated with thrombolysis without the use of special automated software.The MissPerfeCT study is a retrospective observational multicenter cohort study and is registered with clinicaltrials.gov (NCT04277728).

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.

Use of DWI-FLAIR Mismatch to Estimate the Onset Time in Wake-Up Strokes

PURPOSE

To compare the MRI characteristics of patients with wake-up ischemic stroke (WUS) and with ischemic stroke with known onset time (clear-onset-time stroke, COS) to clarify the role of diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch in estimating the onset time of WUS patients.

PATIENTS AND METHODS

Two hundred patients with acute ischemic stroke were selected for complete brain MRI within six hours of symptom onset, including DWI and FLAIR sequences. The patients were divided into WUS (n = 78) and COS (n = 122) groups, based on whether the time of onset was known. The general conditions and imaging characteristics were collected to compare the DWI-FLAIR mismatch features between the two groups at different time intervals.

RESULTS

There was no significant difference in the DWI-FLAIR mismatch on MRI within 2 hour after the first found abnormality between the two groups (50.0% vs 71.8%, p = 0.180). With increasing time, the DWI-FLAIR mismatch decreased substantially in the WUS group, while a higher DWI-FLAIR mismatch presence persisted in the COS group within a four-hour interval from the onset of symptoms to the MRI. The DWI-FLAIR mismatch was significantly lower in the WUS group than in the COS group from symptom identification to MRI at 2-3 h, 3-4 h, and 4-5 h intervals (15% vs 60%, 10.5% vs 48%, 6.7% vs 45.4%; p < 0.01).

CONCLUSION

Our results suggest that the presence of DWI-FLAIR mismatch within 2 h of the first found abnormality was not significantly different between WUS and COS. Therefore, Patients with WUS within 2 hours after the first detected abnormality may be suitable for intravenous thrombolysis.

CT Hypoperfusion-Hypodensity Mismatch to Identify Patients With Acute Ischemic Stroke Within 4.5 Hours of Symptom Onset

BACKGROUND AND OBJECTIVES

To test the hypothesis that CT hypoperfusion-hypodensity mismatch identifies patients with ischemic stroke within 4.5 hours of symptom onset.

METHODS

We therefore performed the Retrospective Multicenter Hypoperfusion-Hypodensity Mismatch for The identification of Patients With Stroke Within 4.5 Hours study of patients with acute ischemic stroke and known time of symptom onset. The predictive values of hypoperfusion-hypodensity mismatch for the identification of patients with symptom onset within 4.5 hours were the main outcome measure.

RESULTS

Of 666 patients, 548 (82.3%) had multimodal CT within 4.5 hours and 118 (17.7%) beyond 4.5 hours. Hypoperfusion-hypodensity mismatch was visible in 516 (94.2%) patients with symptom onset within and in 30 (25.4%) patients beyond 4.5 hours. CT hypoperfusion-hypodensity mismatch identified patients within 4.5 hours of stroke onset with 94.2% (95% confidence interval [CI] 91.9%-95.8%) sensitivity, 74.6% (95% CI 66.0%-81.6%) specificity, 94.5% (95% CI 92.3%-96.1%) positive predictive value, and 73.3% (95% CI 64.8%-80.4%) negative predictive value. Interobserver agreement for hypoperfusion-hypodensity mismatch was substantial (κ = 0.61, 95% CI 0.53-0.69).

DISCUSSION

Patients with acute ischemic stroke with absence of a hypodensity on native CT (NCCT) within the hypoperfused core lesion on perfusion CT (hypoperfusion-hypodensity mismatch) are likely to be within the time window of thrombolysis. Applying this method may guide the decision to use thrombolysis in patients with unknown time of stroke onset.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT04277728.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that CT hypoperfusion-hypodensity mismatch identifies patients with stroke within 4.5 hours of onset.

Safety and efficacy of intravenous thrombolytic treatment in wake-up stroke: Experiences from a single center

OBJECTIVES

Wake-up stroke is an important clinical problem that may account for a quarter of all ischemic strokes. This study aimed to establish the safety and efficacy of intravenous thrombolytic treatment of wake-up strokes by comparing it to the standard thrombolysis treatment in strokes with clear onsets and wake-up strokes that did not receive reperfusion therapy.

METHODS

This retrospective study enrolled 95 patients with ischemic strokes who underwent thrombolytic treatment with alteplase, including nine patients with wake-up strokes. The safety profile (mortality and intracranial bleeding) and efficacy (clinical and functional outcomes on admission, discharge, and 90 days after stroke onset) were evaluated.

RESULTS

When assessed using the modified Rankin scale (mRs), the patients with wake-up strokes had significantly more favorable functional outcomes on discharge when compared to those who received standard thrombolysis (p = .0289). No significant differences were noted when the favorable outcome rate (mRs score = 0-2) at three months post-thrombolysis (Odds ratio [OR] = 2.07; 95% confidence interval [CI] = 0.41-10.6; p = .3807) and safety outcomes (death during hospitalization: OR = 0.49; 95% CI = 0.03-9.11; p = .6295 and intracranial bleeding 24 hr after treatment: OR = 0.43; 95% CI = 0.02-7.58; p = .5707) were compared between the two groups. The Cochran-Mantel-Haenchel shift analysis showed a significantly more favorable distribution of the mRs scores at three months after the stroke onset in the patients with wake-up strokes who were treated with alteplase compared to those who did not receive thrombolysis (OR = 1.42; 95% CI = 1.01-1.82; p = .0426).

CONCLUSIONS

Our study demonstrated that in patients who awaken with stroke symptoms, intravenous thrombolytic treatment is a safe procedure that may lead to favorable outcomes. Further studies should be performed to increase the size of the group of patients with wake-up strokes who can be treated with 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.

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.

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.

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.

Efficacy and Safety of Intravenous Thrombolysis in Patients with Unknown Onset Stroke: A Meta-Analysis

Objectives

Unknown onset stroke (UOS) is usually excluded from intravenous thrombolysis concerning the unclear symptom onset time. Attempts have been done to use thrombolytic therapy in these patients. The current meta-analysis was done to examine the efficacy and safety of intravenous thrombolysis in UOS.

Methods

PubMed, Web of Science, and Cochrane Library were searched for studies comparing thrombolysis with conservative therapy among UOSs. Data of good outcome (mRS, 0-2), mortality, and intracerebral hemorrhage (ICH) and symptomatic ICH (sICH) were extracted and analyzed using the Revman 5.2 software.

Results

In total, 8 studies with 1271 subjects (542 with thrombolysis and 729 with conservative therapy) were included in this meta-analysis. The data showed that patients receiving thrombolysis had a higher incidence of 90-day good outcome (P = 0.0005) than conservative therapy. The comparison of discharge (P = 0.89) and 90-day mortality (P = 0.10) in both groups did not find any significances. The incidences of ICH (P = 0.42) and sICH (P = 0.06) were relatively comparable between the two therapies.

Conclusions

Intravenous thrombolysis is a better choice for UOS patients for its efficacy and safety. In addition, pretreatment imaging assessment is beneficial for improving the efficacy of thrombolytic therapy. However, it needs more supporting evidences for clinical use in the future.

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.

Intravenous thrombolysis in wake-up stroke: real-world data from the Austrian Stroke Unit Registry

BACKGROUND AND PURPOSE

Data on real-world experience with intravenous thrombolysis (IV tPA) in wake-up stroke (WUS) are limited. The aim of this study was to examine the efficacy and safety of IV tPA in patients with WUS included in the Austrian Stroke Unit Registry.

METHODS

Data from a large nationwide stroke unit registry including initial stroke severity, vascular risk factors, comorbidities, treatment with IV tPA, symptomatic intracerebral haemorrhage (sICH) and functional outcome were extracted and analysed. Patients with WUS were compared with patients with known-onset stroke (KOS) regarding the frequency of IV tPA treatment, neurological improvement (National Institutes of Health Stroke Scale score ≥4), sICH and 3-month functional outcome by modified Rankin Scale score using standard statistical tests.

RESULTS

A total of 107 895 stroke patients entered the analysis, including 12 534 with WUS and 91 899 with KOS. Altogether, 904 (7.2%) patients with WUS received IV tPA as compared with 16 694 (18.2%) patients with KOS. Patients with WUS who received IV tPA treatment had twofold higher initial National Institutes of Health Stroke Scale score (median 8 vs. median 4) as compared with patients with KOS. There was no statistical difference in functional outcome by modified Rankin Scale score 0-1 at 3 months between patients with WUS and patients with KOS treated with IV tPA (adjusted odds ratio, 1.08; 95% confidence interval, 0.9-1.31). Also, the rate of sICH did not differ (4.1% vs. 4%, P = 0.852).

CONCLUSIONS

In this large non-randomized comparison, the safety and efficacy of IV tPA in patients with WUS in the real-world setting seems to be comparable to patients with KOS.

Re-evaluation of the stroke prognostication using age and NIH Stroke Scale index (SPAN-100 index) in IVT patients - the-SPAN 10065 index

Background

The SPAN-100 index adds patient age and baseline NIHSS-score and was introduced to predict clinical outcome after acute ischemic stroke (AIS). Even with high NIHSS-scores younger patients cannot reach a SPAN-100-positive status (index ≥100). We aimed to evaluate the SPAN-100 index among a large, contemporary cohort of i.v.-thrombolysed AIS-patients and exclusively among older patients who can at least theoretically achieve SPAN-100-positivity.

Methods

The SPAN-100 index was applied to AIS-patients receiving i.v.-thrombolysis (IVT) in our institution between 01/2006 and 01/2013. Clinical outcome and symptomatic intracerebral hemorrhage rates were compared between SPAN-100-positive and -negative patients. Furthermore we excluded patients < 65 years, without any theoretical chance to achieve SPAN-100-positivity, and re-evaluated the index (SPAN⁶⁵–100 index).

Results

SPAN-100-positive IVT-patients (124/1002) had a 9-fold increased risk for unfavorable outcome compared to SPAN-negative patients (OR 9.39; 95% CI 5.87–15.02; p <  0.001). The odds ratio for mortality was 7.48 (95% CI 4.90–11.43; p <  0.001). No association was found between SPAN-100-positivity and sICH-incidence (OR 0.88; 95% CI 0.31–2.53; p = 0.810).

SPAN⁶⁵–100-positivity (124/741) was associated with an 8-fold increased risk for unfavorable outcome (OR 7.6; 95% CI 4.71–12.22; p <  0.001) but not associated with higher sICH-rates (OR 0.86; 95% CI 0.29–2.53; p <  0.001).

Conclusions

Also for patients ≥65 years the SPAN-100 index can be a fast, easy method to predict clinical outcome of IVT-patients in everyday practice. However, it should not be used to determine the risk of sICH after IVT. Based on a SPAN-positive status IVT should not be withheld from AIS-patients merely because of feared sICH-complications.

Penumbral Imaging-Based Thrombolysis with Tenecteplase Is Feasible up to 24 Hours after Symptom Onset

BACKGROUND AND PURPOSE

Thrombolysis >4.5 hours after ischemic stroke onset is unproven. We assessed the feasibility of tenecteplase (TNK) treatment in patients with evidence of an ischemic penumbra 4.5 to 24 hours after onset.

METHODS

Acute ischemic stroke patients underwent perfusion computed tomography (CT)/magnetic resonance imaging. Patients with cerebral blood volume (CBV) or diffusion weighted imaging Alberta Stroke Program Early CT Scores (ASPECTS) >6 and mismatch score >2 (defined as >2 ASPECTS regions with delay on mean transit time maps and normal CBV) were eligible for treatment with TNK (0.25 mg/kg). Patients with mismatch patterns enrolled in non-endovascular/non-thrombolysis trials and those without mismatch patterns served as comparators.

RESULTS

The median (interquartile range) baseline National Institutes of Health Stroke Scale (NIHSS) in TNK treated patients (n=16) was 12 (range, 8 to 15). In the untreated mismatch (n=18) and nonmismatch (n=23) groups, the baseline NIHSS was 12 (range, 7 to 12) and 16 (range, 8 to 20; P=0.09) respectively. There was one symptomatic hemorrhage each in the TNK group (parenchymal hematoma [PH] 2) and non-mismatch group (PH 2). Penumbral salvage volumes were higher in TNK treated patients (48.3 mL [range, 24.9 to 80.4]) than the non-mismatch (-90.8 mL [range, -197 to -20]; P<0.0001) patients.

CONCLUSIONS

This prospective, non-randomized study supports the feasibility of TNK therapy in patients with evidence of ischemic penumbra 4 to 24 hours after onset.

About 30% of wake-up stroke patients may be candidate for the tPA therapy using Negative-FLAIR as a "tissue clock"

BACKGROUND AND PURPOSE

Recent studies using magnetic resonance imaging (MRI) have reported that wake-up stroke (WUS) patients may be able to be treated using tissue-plasminogen activator (tPA) when showing no ischemia on fluid-attenuated inversion recovery (Negative-FLAIR). We investigated the frequency of WUS and calculated what percentage of WUS patients with Negative-FLAIR meets most of the conventional tPA criteria. We did not include a time parameter in this study.

METHODS

Consecutive patients with acute stroke affecting the anterior circulation who presented within 12h of onset were enrolled. All patients were examined using diffusion-weighted imaging (DWI) and FLAIR. As large infarctions are excluded from tPA therapy, an Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS) of ≤3 was used as the upper limit for exclusion.

RESULTS

A total of 816 consecutive patients were included in the study and were separated into two groups; 163 (20%) WUS patients as the WUS group, and 653 (80%) non-WUS patients as the non-WUS group. The median National Institutes of Health Stroke Scale (NIHSS) score on admission was 7 (interquartile range, 3-17) in the WUS group and 8 (3-16) in the non-WUS group (p=0.313). MRI study revealed Negative-FLAIR in 67 (41%) of 163 patients in the WUS group. Of the 67 patients with Negative-FLAIR, 19 patients were excluded from tPA therapy. Therefore, 48 (29%) of the 163 wake-up stroke patients met the tPA criteria.

CONCLUSIONS

About 30% of WUS patients may be candidates for tPA therapy based upon Negative-FLAIR findings.

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 Thrombolysis in Unknown-Onset Stroke: Results From the Safe Implementation of Treatment in Stroke-International Stroke Thrombolysis Registry

BACKGROUND AND PURPOSE

Stroke patients with unknown onset (UKO) are excluded from thrombolytic therapy. We aim to study the safety and efficacy of intravenous alteplase in ischemic stroke patients with UKO of symptoms compared with those treated within 4.5 hours in a large cohort.

METHODS

Data were analyzed from 47 237 patients with acute ischemic stroke receiving intravenous tissue-type plasminogen activator in hospitals participating in the Safe Implementation of Treatment in Stroke-International Stroke Thrombolysis Registry between 2010 and 2014. Two groups were defined: (1) patients with UKO (n=502) and (2) patients treated within 4.5 hours of stroke onset (n=44 875). Outcome measures were symptomatic intracerebral hemorrhage per Safe Implementation of Treatment in Stroke on the 22 to 36 hours post-treatment neuroimaging and mortality and functional outcome assessed by the modified Rankin Scale at 3 months.

RESULTS

Patients in UKO group were significantly older, had more severe stroke at baseline, and longer door-to-needle times than patients in the ≤4.5 hours group. Logistic regression showed similar risk of symptomatic intracerebral hemorrhage (adjusted odds ratio, 1.09; 95% confidence interval, 0.44-2.67) and no significant differences in functional independency (modified Rankin Scale score of 0-2; adjusted odds ratio, 0.79; 95% confidence interval, 0.56-1.10), but higher mortality (adjusted odds ratio, 1.58; 95% confidence interval, 1.04-2.41) in the UKO group compared with the ≤4.5 hours group. Patients treated within 4.5 hours showed reduced disability over the entire range of modified Rankin Scale compared with the UKO group (common adjusted odds ratio, 1.29; 95% confidence interval, 1.01-1.65).

CONCLUSIONS

Our data suggest no excess risk of symptomatic intracerebral hemorrhage but increased mortality and reduced favorable outcome in patients with UKO stroke compared with patients treated within the approved time window.

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.

Stroke- on- Awakening: Safety of CT-CTA Based Selection for Reperfusion Therapy

BACKGROUND

We studied the safety of use of acute reperfusion therapies in patients with stroke- on- awakening using a computed tomographic angiography (Cta) based large vessel occlusion-good scan paradigm in clinical routine.

METHODS

the Cta database of the Calgary stroke program was reviewed for the period January 2003-March 2010. patients with stroke-on-awakening with large artery occlusions on Cta, who received conservative, iV thrombolytic and/or endovascular treatment at discretion of the attending stroke neurologist were analyzed. time of onset was defined by the time last seen or known to be normal. Baseline non-contrast Ct scan (nCCt) alberta Stroke program early Ct Score (aSpeCtS) > 7 was considered a good scan. hemorrhage was defined on follow-up brain imaging using eCaSS 3 criteria. independence (mrS≤2) at three months was considered a good clinical outcome. Standard descriptive statistics and multivariable analysis were done.

RESULTS

among 532 patients with large artery occlusions, 70 patients with stroke-on-awakening (13.1%) were identified. the median age was 69.5 (iQr 24) and 41 (58.6%) were female; 41 (58.6%) received anti-platelets only and 29 (41.4%) received thrombolytic treatment [iV-12 (17.1%), iV/ia-12 (17.1%) and ia-5(7.1%)]. unadjusted analysis showed that baseline nCCt aSpeCtS ≤ 7 (p=0.002) and higher nihSS scores (p=0.018) were associated with worse outcomes. there were no ph2 hemorrhages in the iV thrombolytic or endovascular treated group. functional outcome was not different by treatment.

CONCLUSION

When carefully selected using Ct –Cta, by a good scan (aSpeCtS > 7) occlusion paradigm, acute reperfusion therapies in patients with stroke-on-awakening can be performed safely in clinical routine.

Association Between Time From Stroke Onset and Fluid-Attenuated Inversion Recovery Lesion Intensity Is Modified by Status of Collateral Circulation

BACKGROUND AND PURPOSE

In patients with acute stroke, the intensity of a fluid-attenuated inversion recovery (FLAIR) lesion in the region of diffusion restriction is associated with time from symptom onset. We hypothesized that collateral status as assessed by the hypoperfusion intensity ratio could modify the association between time from stroke onset and FLAIR lesion intensity.

METHODS

From the AX200 for ischemic stroke trial, 141 patients had appropriate FLAIR, diffusion-weighted imaging, and perfusion-weighted imaging. In the region of nonreperfused core, we calculated voxel-based relative FLAIR (rFLAIR) signal intensity. The hypoperfusion intensity ratio was defined as the ratio of the Tmax >10 s lesion over the Tmax >6 s lesion volume. A hypoperfusion intensity ratio threshold of ≤0.4 was used to dichotomize good versus poor collaterals. We studied the interaction between collateral status on the association between time from symptom onset and FLAIR intensity.

RESULTS

Time from symptom onset was associated with the rFLAIR intensity in the region of nonreperfused core (B=1.05; 95% confidence interval, 1.0-1.1). We identified an interaction between this association and collateral status; an association was present between time and rFLAIR intensity in patients with poor collaterals (r=0.53), but absent in patients with good collaterals (r=0.17; P=0.04).

CONCLUSIONS

Our findings show that the relationship between time from symptom onset and rFLAIR lesion intensity depends on collateral status. In patients with good collaterals, the development of an rFLAIR-positive lesion is less dependent on time from symptom onset compared with patients with poor collaterals.

Modeling the Cost Effectiveness of Neuroimaging-Based Treatment of Acute Wake-Up Stroke

BACKGROUND

Thrombolytic treatment (tissue-type plasminogen activator [tPA]) is only recommended for acute ischemic stroke patients with stroke onset time <4.5 hours. tPA is not recommended when stroke onset time is unknown. Diffusion-weighted MRI (DWI) and fluid attenuated inversion recovery (FLAIR) MRI mismatch information has been found to approximate stroke onset time with some accuracy. Therefore, we developed a micro-simulation model to project health outcomes and costs of MRI-based treatment decisions versus no treatment for acute wake-up stroke patients.

METHODS AND FINDINGS

The model assigned simulated patients a true stroke onset time from a specified probability distribution. DWI-FLAIR mismatch estimated stroke onset <4.5 hours with sensitivity and specificity of 0.62 and 0.78, respectively. Modified Rankin Scale (mRS) scores reflected tPA treatment effectiveness accounting for patients' true stroke onset time. Discounted lifetime costs and benefits (quality-adjusted life years [QALYs]) were projected for each strategy. Incremental cost-effectiveness ratios (ICERs) were calculated for the MRI-based strategy in base-case and sensitivity analyses. With no treatment, 45.1% of simulated patients experienced a good stroke outcome (mRS score 0-1). Under the MRI-based strategy, in which 17.0% of all patients received tPA despite stroke onset times >4.5 hours, 46.3% experienced a good stroke outcome. Lifetime discounted QALYs and costs were 5.312 and $88,247 for the no treatment strategy and 5.342 and $90,869 for the MRI-based strategy, resulting in an ICER of $88,000/QALY. Results were sensitive to variations in patient- and provider-specific factors such as sleep duration, hospital travel and door-to-needle times, as well as onset probability distribution, MRI specificity, and mRS utility values.

CONCLUSIONS

Our model-based findings suggest that an MRI-based treatment strategy for this population could be cost-effective and quantifies the impact that patient- and provider-specific factors, such as sleep duration, hospital travel and door-to-needle times, could have on the optimal decision for wake-up stroke patients.

Favorable Bridging Therapy Based on DWI-FLAIR Mismatch in Patients with Unclear-Onset Stroke

BACKGROUND AND PURPOSE

Standard selection criteria for revascularization therapy usually exclude patients with unclear-onset stroke. Our aim was to evaluate the efficacy and safety of revascularization therapy in patients with unclear-onset stroke in the anterior circulation and to identify the predictive factors for favorable clinical outcome.

MATERIALS AND METHODS

We retrospectively analyzed 41 consecutive patients presenting with acute stroke with unknown time of onset treated by intravenous thrombolysis and/or mechanical thrombectomy. Only patients without well-developed fluid-attenuated inversion recovery changes of acute diffusion lesions on MR imaging were enrolled. Twenty-one patients were treated by intravenous thrombolysis; 19 received, simultaneously, intravenous thrombolysis and mechanical thrombectomy (as a bridging therapy); and 1 patient, endovascular therapy alone. Clinical outcome was evaluated at 90 days by using the mRS. Mortality and symptomatic intracranial hemorrhage were also reported.

RESULTS

Median patient age was 72 years (range, 17-89 years). Mean initial NIHSS score was 14.5 ± 5.7. Successful recanalization (TICI 2b-3) was assessed in 61% of patients presenting with an arterial occlusion, symptomatic intracranial hemorrhage occurred in 2 patients (4.9%), and 3 (7.3%) patients died. After 90 days, favorable outcome (mRS 0-2) was observed in 25 (61%) patients. Following multivariate analysis, initial NIHSS score (OR, 1.43; 95% CI, 1.13-1.82; P = .003) and bridging therapy (OR, 37.92; 95% CI, 2.43-591.35; P = .009) were independently associated with a favorable outcome at 3 months.

CONCLUSIONS

The study demonstrates the safety and good clinical outcome of acute recanalization therapy in patients with acute stroke in the anterior circulation and an unknown time of onset and a DWI/FLAIR mismatch on imaging. Moreover, bridging therapy versus intravenous thrombolysis alone was independently associated with favorable outcome at 3 months.

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.

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.

Optimal MRI sequence for identifying occlusion location in acute stroke: which value of time-resolved contrast-enhanced MRA?

BACKGROUND AND PURPOSE

Identifying occlusion location is crucial for determining the optimal therapeutic strategy during the acute phase of ischemic stroke. The purpose of this study was to assess the diagnostic efficacy of MR imaging, including conventional sequences plus time-resolved contrast-enhanced MRA in comparison with DSA for identifying arterial occlusion location.

MATERIALS AND METHODS

Thirty-two patients with 34 occlusion levels referred for thrombectomy during acute cerebral stroke events were consecutively included from August 2010 to December 2012. Before thrombectomy, we performed 3T MR imaging, including conventional 3D-TOF and gradient-echo T2 sequences, along with time-resolved contrast-enhanced MRA of the extra- and intracranial arteries. The 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA results were consensually assessed by 2 neuroradiologists and compared with prethrombectomy DSA results in terms of occlusion location. The Wilcoxon test was used for statistical analysis to compare MR imaging sequences with DSA, and the κ coefficient was used to determine intermodality agreement.

RESULTS

The occlusion level on the 3D-TOF and gradient-echo T2 images differed significantly from that of DSA (P < .001 and P = .002, respectively), while no significant difference was observed between DSA and time-resolved contrast-enhanced MRA (P = .125). κ coefficients for intermodality agreement with DSA (95% CI, percentage agreement) were 0.43 (0.3%-0.6; 62%), 0.32 (0.2%-0.5; 56%), and 0.81 (0.6%-1.0; 88%) for 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA, respectively.

CONCLUSIONS

The time-resolved contrast-enhanced MRA sequence proved reliable for identifying occlusion location in acute stroke with performance superior to that of 3D-TOF and gradient-echo T2 sequences.

Current concepts on magnetic resonance imaging (MRI) perfusion-diffusion assessment in acute ischaemic stroke: a review & an update for the clinicians

Recently, several medical societies published joint statements about imaging recommendations for acute stroke and transient ischaemic attack patients. In following with these published guidelines, we considered it appropriate to present a brief, practical and updated review of the most relevant concepts on the MRI assessment of acute stroke. Basic principles of the clinical interpretation of diffusion, perfusion, and MRI angiography (as part of a global MRI protocol) are discussed with accompanying images for each sequence. Brief comments on incidence and differential diagnosis are also included, together with limitations of the techniques and levels of evidence. The purpose of this article is to present knowledge that can be applied in day-to-day clinical practice in specialized stroke units or emergency rooms to attend patients with acute ischaemic stroke or transient ischaemic attack according to international standards.

Endovascular therapy of wake-up strokes in the modern era of stent retriever thrombectomy

Background

Endovascular treatment of wake-up strokes (WUS) has been previously described, mostly with the use of pharmacological thrombolysis or first generation thrombectomy devices.

Objective

To describe outcomes of WUS treated with modern endovascular therapy since the Food and Drug Administration approval of stent retrievers, and to identify predictors of good clinical outcome in this population of stroke patients.

Methods

We performed a multicenter retrospective analysis of consecutive patients with WUS who underwent thrombectomy with stent retrievers Trevo (Stryker, Kalamazoo, Michigan, USA) and Solitaire FR (Covidien, Irvine, California, USA), or primary aspiration thrombectomy. We correlated favorable clinical outcomes with demographic, clinical, and technical characteristics.

Results

52 patients were included in this study; 46 (88%) cases were treated with stent retrievers and 6 (12%) were treated with primary aspiration thrombectomy alone. Successful recanalization (Thrombolysis in Cerebral Infarction (TICI) 2b/3) was achieved in 36 (69%) patients. Favorable clinical outcome at 3 months, defined as a modified Rankin Scale score of 0–2, was achieved in 25 (48%) patients. Duration of intervention <30 min and its success, defined as TICI 2b/3 recanalization, were strong predictors of favorable clinical outcome at 90 days (p<0.001 and p<0.0001, respectively).

Conclusions

Our study indicates that endovascular treatment of WUS with stent retrievers and aspiration thrombectomy is safe and effective.

The role of imaging in acute ischemic stroke

Neuroimaging has expanded beyond its traditional diagnostic role and become a critical tool in the evaluation and management of stroke. The objectives of imaging include prompt accurate diagnosis, treatment triage, prognosis prediction, and secondary preventative precautions. While capitalizing on the latest treatment options and expanding upon the "time is brain" doctrine, the ultimate goal of imaging is to maximize the number of treated patients and improve the outcome of one the most costly and morbid disease. A broad overview of comprehensive multimodal stroke imaging is presented here to affirm its utilization.

Wake-up stroke and stroke of unknown onset: a critical review

Patients, who wake up with an ischemic stroke, account for a large number of the total stroke population, due to circadian morning predominance of stroke. Currently, this subset of patients is excluded from revascularization-therapy since no exact time of onset is known. A large group of these patients might be eligible for therapy. In this review, we assessed the current literature about the hypothesis that wake-up-strokes occur just prior on awakening and if this subgroup differs in characteristics compared to the overall stroke population. We looked at the safety and efficacy of thrombolysis and interventional techniques in the group of patients with unknown stroke-onset. We performed a meta-analysis of the diagnostic accuracy of the diffusion-FLAIR mismatch in identifying stroke within 3 and 4.5 h. The different imaging-selection criteria that can be used to treat these patients are discussed. Additional research on imaging findings associated with recent stroke and penumbral imaging will eventually lead to a shift from a rigid time-frame based therapy to a tissue-based individualized treatment approach.

THrombolysis for Acute Wake-up and unclear-onset Strokes with alteplase at 0·6 mg/kg (THAWS) Trial

Rationale

Because of lack of information regarding timing of stroke, patients who suffer stroke during sleep are generally ineligible for intravenous thrombolysis, although many of these patients could potentially recover with this treatment. Magnetic resonance image findings with positive diffusion-weighted imaging and no marked parenchymal hyperintensity on fluid-attenuated inversion recovery (negative pattern) can identify acute ischemic stroke patients within 4·5 h from symptom onset.

Aims

The THrombolysis for Acute Wake-up and unclear-onset Strokes with alteplase at 0·6 mg/kg trial aims to determine the efficacy and safety of intravenous thrombolysis with alteplase at 0·6 mg/kg body weight, the approved dose for Japanese stroke patients, using magnetic resonance image-based selection in ischemic stroke patients with unclear time of symptom onset, and compare findings with standard treatment.

Design

This is an investigator-initiated, multicenter, prospective, randomized, open-treatment, blinded-end-point clinical trial. The design is similar to the Efficacy and Safety of MRI-based Thrombolysis in Wake-up Stroke trial. Patients with unclear-onset time of stroke symptoms beyond 4·5 h and within 12 h after the time of the last-known-well period and within 4·5 h after symptom recognition, who showed a negative fluid-attenuated inversion recovery pattern, are randomized to either intravenous thrombolysis or standard treatment.

Study outcomes

The primary efficacy end-point is modified Rankin Scale 0–1 at 90 days. The safety outcome measures are symptomatic intracranial hemorrhage at 22–36 h, and major bleeding and mortality at 90 days.

Discussion

This trial may help determine if low-dose alteplase at 0·6 mg/kg should be recommended as a routine clinical strategy for ischemic stroke patients with unclear-onset time.

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.

Safety and effectiveness of endovascular treatment of stroke with unknown time of onset

BACKGROUND

Currently, treatment options for patients with strokes with unknown time of onset (UKO) remain limited. With the advance of neuroimaging and endovascular treatment (EVT), selected patients might have a chance of a therapeutic option. We sought to compare clinical outcome after EVT in patients with known time of stroke onset (KO) and in those with UKO.

METHODS

We prospectively registered consecutive patients with acute large artery occlusion of the anterior territory who underwent EVT. Multimodal MR or Alberta Stroke Program early CT score (ASPECTS) and transcranial color-coded Duplex sonography were used to select patients for EVT. Recanalization, periprocedural complications, intracranial hemorrhage (ICH) and outcome were recorded. Symptomatic ICH (sICH) was defined as a worsening of ≥4 points in the National Institutes of Health Stroke Scale (NIHSS) score within 36 h in any bleeding. Favorable outcome was defined as a modified Rankin score ≤2 at 3 months.

RESULTS

A total of 141 patients were studied, 109 with KO and 32 with UKO. Mean age was 66.5 versus 64.7 years (p = 0.005) and median baseline NIHSS was 18 versus 17 (p = 0.095), respectively. Prior IV tPA was more frequently administered to KO patients (62.4 vs. 9.4%, p < 0.001), whereas patient selection using multimodal MR was more frequent in patients with UKO (78.1 vs. 45.4%, p < 0.001). Median time from stroke onset or from the last time the patient was seen well to groin puncture and to recanalization was significantly longer in patients with UKO, but no differences were found in the duration of the procedure. For KO/UKO patients recanalization was seen in 77.1 vs. 65.7% (p = 0.084), sICH occurred in 10 versus 0% (p = 0.061) and favorable outcome at 3 months was achieved in 41.3 versus 50% (p = 0.382), respectively.

CONCLUSIONS

Clinical outcomes in this series of EVT in ischemic stroke patients due to large anterior arterial occlusion with salvageable brain are similar for patients treated with KO and UKO. These data support a randomized study of EVT in extended or uncertain time windows..

Imaging recommendations for acute stroke and transient ischemic attack patients: a joint statement by the American Society of Neuroradiology, the American College of Radiology and the Society of NeuroInterventional Surgery

In the article entitled "Imaging Recommendations for Acute Stroke and Transient Ischemic Attack Patients: A Joint Statement by the American Society of Neuroradiology, the American College of Radiology and the Society of NeuroInterventional Surgery", we are proposing a simple, pragmatic approach that will allow the reader to develop an optimal imaging algorithm for stroke patients at their institution.

Imaging recommendations for acute stroke and transient ischemic attack patients: A joint statement by the American Society of Neuroradiology, the American College of Radiology, and the Society of NeuroInterventional Surgery

SUMMARY

Stroke is a leading cause of death and disability worldwide. Imaging plays a critical role in evaluating patients suspected of acute stroke and transient ischemic attack, especially before initiating treatment. Over the past few decades, major advances have occurred in stroke imaging and treatment, including Food and Drug Administration approval of recanalization therapies for the treatment of acute ischemic stroke. A wide variety of imaging techniques has become available to assess vascular lesions and brain tissue status in acute stroke patients. However, the practical challenge for physicians is to understand the multiple facets of these imaging techniques, including which imaging techniques to implement and how to optimally use them, given available resources at their local institution. Important considerations include constraints of time, cost, access to imaging modalities, preferences of treating physicians, availability of expertise, and availability of endovascular therapy. The choice of which imaging techniques to employ is impacted by both the time urgency for evaluation of patients and the complexity of the literature on acute stroke imaging. Ideally, imaging algorithms should incorporate techniques that provide optimal benefit for improved patient outcomes without delaying treatment.

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.

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

RATIONALE

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

AIMS AND HYPOTHESIS

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

DESIGN

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

STUDY OUTCOME

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

DISCUSSION

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

Reperfusion therapy in unclear-onset stroke based on MRI evaluation (RESTORE): a prospective multicenter study

BACKGROUND AND PURPOSE

Unclear-onset strokes are generally excluded from time-based thrombolytic therapy. We examined the safety and feasibility of magnetic resonance imaging-based reperfusion therapy in unclear-onset stroke.

METHODS

This prospective, multicenter, single-arm study screened consecutive unclear-onset stroke patients within 6 hours of symptom detection. Patients with perfusion-diffusion mismatch>20% and negative or subtle fluid-attenuated inversion recovery changes were treated with intravenous tissue plasminogen activator, intra-arterial therapy, or a combination. The safety outcome was symptomatic intracranial hemorrhage within 48 hours after treatment. The primary efficacy outcome was a 3-month modified Rankin Scale score of 0 to 2. Controls were untreated unclear-onset stroke patients prospectively captured in stroke registries.

RESULTS

Of 430 unclear-onset stroke patients, 83 (19.3%) received reperfusion therapy (mean age, 67.5±10.4 years; males, 66.3%; median baseline National Institutes of Health Stroke Scale, 14). Symptomatic intracranial hemorrhage with any neurological decline developed in 5 patients (6.0%). Symptomatic intracranial hemorrhage with National Institutes of Health Stroke Scale worsening ≥4 developed in 3 patients (3.6%). Thirty-seven patients (44.6%) achieved modified Rankin Scale score of 0 to 2, and 24 (28.9%) had modified Rankin Scale score of 0 to 1. Female, baseline National Institutes of Health Stroke Scale score, no immediate or early recanalization, and more white blood cells were independent predictors of poor outcome. Compared with untreated controls, the treated group was significantly associated with good outcomes of modified Rankin Scale score of 0 to 2 after adjusting for age, sex, and baseline National Institutes of Health Stroke Scale in logistic regression analysis (odds ratio, 2.25; 95% CI, 1.14-4.49).

CONCLUSIONS

In unclear-onset stroke patients, magnetic resonance imaging-based reperfusion therapy was feasible and safe. Randomized controlled trials are warranted to confirm the benefit of reperfusion therapy for unclear-onset stroke.

Wake-up or unclear-onset strokes: are they waking up to the world of thrombolysis therapy?

Wake-up or unclear-onset strokes occur in up to one-fourth of patients with ischemic stroke. Although stroke severity and clinical outcomes appear to be poorer in wake-up strokes than nonwake-up strokes, many patients with wake-up strokes do not receive thrombolytic therapy because stroke onset time cannot be determined. Recent studies have suggested, however, that the actual onset time of wake-up stroke is close to the wake-up time. Furthermore, advanced imaging technologies may enable us to identify patients with favorable risk-benefit profiles for thrombolysis. Indeed, empirical thrombolytic treatments have suggested safety and feasibility of such therapy in these patients. Based on these promising results and the development of multimodal imaging methods, prospective thrombolysis trials using predefined imaging criteria are currently under way to test the safety and efficacy of thrombolysis in patients with wake-up or unclear-onset strokes. The establishment of optimal acute treatment strategies in this important yet so far neglected group of patients is eagerly awaited.

Diffusion-weighted imaging-fluid attenuated inversion recovery mismatch in nocturnal stroke patients with unknown time of onset

BACKGROUND

More than a quarter of patients with ischemic stroke (IS) are excluded from thrombolysis because of an unknown time of symptom onset. Recent evidence suggests that a mismatch between diffusion-weighted imaging (DWI) and fluid attenuated inversion recovery (FLAIR) imaging could be used as a surrogate for the time of stroke onset. We compared used the DWI-FLAIR mismatch and the FLAIR/DWI ratio to estimate the time of onset in a group of patients with nocturnal strokes and unknown time of onset.

METHODS

We used a prospectively collected acute IS patient database with MRI as the initial imaging modality. Nineteen selected nocturnal stroke patients with unknown time of onset were compared with 22 patients who had an MRI scan within 6 hours from stroke onset (control A) and 19 patients who had an MRI scan between 6 and 12 hours (control B). DWI and FLAIR signal was rated as normal or abnormal. FLAIR/DWI ratio was calculated from independent DWI and FLAIR ischemic lesion volumes using semiautomatic software.

RESULTS

The DWI-FLAIR mismatch was different among groups (unknown 43.7%; control A 63.6%; control B 10.5%; Fisher-Freeman-Halton test; P = .001). There were significant differences in FLAIR/DWI ratio among the 3 groups (unknown 0.05 ± 0.12; control A 0.17 ± 0.15; control B 0.04 ± 0.06; Kruskal-Wallis test; P < .0001). Post-hoc pairwise comparisons revealed that FLAIR/DWI ratio from the unknown group was significantly different from the control B group (P = .0045) but not different from the control A group. DWI volumes were not different among the 3 groups.

CONCLUSIONS

A large proportion of patients with nocturnal IS and an unknown time of stroke initiation have a DWI-FLAIR mismatch, suggesting a recent onset of stroke.

DWI-FLAIR mismatch for the identification of patients with acute ischaemic stroke within 4·5 h of symptom onset (PRE-FLAIR): a multicentre observational study

BACKGROUND

Many patients with stroke are precluded from thrombolysis treatment because the time from onset of their symptoms is unknown. We aimed to test whether a mismatch in visibility of an acute ischaemic lesion between diffusion-weighted MRI (DWI) and fluid-attenuated inversion recovery (FLAIR) MRI (DWI-FLAIR mismatch) can be used to detect patients within the recommended time window for thrombolysis.

METHODS

In this multicentre observational study, we analysed clinical and MRI data from patients presenting between Jan 1, 2001, and May 31, 2009, with acute stroke for whom DWI and FLAIR were done within 12 h of observed symptom onset. Two neurologists masked to clinical data judged the visibility of acute ischaemic lesions on DWI and FLAIR imaging, and DWI-FLAIR mismatch was diagnosed by consensus. We calculated predictive values of DWI-FLAIR mismatch for the identification of patients with symptom onset within 4·5 h and within 6 h and did multivariate regression analysis to identify potential confounding covariates. This study is registered with ClinicalTrials.gov, number NCT01021319.

FINDINGS

The final analysis included 543 patients. Mean age was 66·0 years (95% CI 64·7-67·3) and median National Institutes of Health Stroke Scale score was 8 (IQR 4-15). Acute ischaemic lesions were identified on DWI in 516 patients (95%) and on FLAIR in 271 patients (50%). Interobserver agreement for acute ischaemic lesion visibility on FLAIR imaging was moderate (κ=0·569, 95% CI 0·504-0·634). DWI-FLAIR mismatch identified patients within 4·5 h of symptom onset with 62% (95% CI 57-67) sensitivity, 78% (72-84) specificity, 83% (79-88) positive predictive value, and 54% (48-60) negative predictive value. Multivariate regression analysis identified a longer time to MRI (p<0·0001), a lower age (p=0·0009), and a larger DWI lesion volume (p=0·0226) as independent predictors of lesion visibility on FLAIR imaging.

INTERPRETATION

Patients with an acute ischaemic lesion detected with DWI but not with FLAIR imaging are likely to be within a time window for which thrombolysis is safe and effective. These findings lend support to the use of DWI-FLAIR mismatch for selection of patients in a future randomised trial of thrombolysis in patients with unknown time of symptom onset.

FUNDING

Else Kröner-Fresenius-Stiftung, National Institutes of Health.

MRI-based intravenous thrombolysis in stroke patients with unknown time of symptom onset

BACKGROUND

Currently, stroke patients with unknown time of symptom onset (UTOS) are excluded from therapy with intravenous tissue Plasminogen Activator. We hypothesized that MRI-based intravenous thrombolysis is safe in UTOS.

METHODS

We analyzed radiological and clinical data as well as outcomes of stroke patients (including UTOS) who received intravenous thrombolytic therapy after MRI.

RESULTS

Compared to patients with known time of symptom onset (n=131), UTOS (n=17) were older (81, 71-88 vs. 75 years, 66-82, P=0.03), had a longer median time between last-seen-well and thrombolysis (12.3 h, IQR 11.5-15.2 h vs. 2.1 h, 1.8-2.8 h, P<0.01), had a longer median door-to-needle time (86 min, 49-112 vs. 60 min, 49-76, P=0.02), and a higher rate of arterial obstruction on MR-angiography (82.4% vs. 56.5%, P=0.04). No symptomatic intracerebral hemorrhage occurred in UTOS. After 3 months, there was no significant difference between groups concerning good functional outcome (modified Rankin Scale 0-2; 35.3% vs. 49.6%, P=0.26) or mortality (0% vs. 15.3%, P=0.08). In multivariate analyses including age, gender, baseline NIHSS, and atrial fibrillation UTOS did not have an independent effect on good functional outcome after 3 months (OR 1.16; 0.32-4.12, P=0.81).

CONCLUSIONS

Thrombolysis after MRI seems safe and effective in UTOS. This observation may encourage those who plan prospective placebo-controlled trials of thrombolytics in this subgroup of stroke patients.

[Difficult decisions in stroke therapy]

In numerous situations stroke physicians face a lack of evidence during their daily practice. In this report the authors address some of the difficult treatment decisions encountered in acute therapy and secondary prevention. Examples include off-label thrombolysis and prevention in high-risk situations. The available data from trials and registries are discussed, and personal views and recommendations are expressed.