Timing of recanalization after tissue plasminogen activator therapy determined by transcranial doppler correlates with clinical recovery from ischemic stroke

Validation of the transcranial Doppler rescue criteria for mechanical thrombectomy

BACKGROUND AND PURPOSE

Transcranial Doppler (TCD) identifies acute stroke patients with arterial occlusion where treatment may not effectively open the blocked vessel. This study aimed to examine the clinical utility and prognostic value of TCD flow findings in patients enrolled in a multicenter prospective study (CLOTBUST-PRO).

METHODS

Patients enrolled with intracranial occlusion on computed tomography angiography (CTA) who underwent urgent TCD evaluation before intravenous thrombolysis was included in this analysis. TCD findings were assessed using the mean flow velocity (MFV) ratio, comparing the reciprocal ratios of the middle cerebral artery (MCA) depths bilaterally (affected MCA-to-contralateral MCA MFV [aMCA/cMCA MFV ratio]).

RESULTS

A total of 222 patients with intracranial occlusion on CTA were included in the study (mean age: 64 ± 14 years, 62% men). Eighty-eight patients had M1 MCA occlusions; baseline mean National Institutes of Health Stroke Scale (NIHSS) score was 16, and a 24-hour mean NIHSS score was 10 points. An aMCA/cMCA MFV ratio of <.6 had a sensitivity of 99%, specificity of 16%, positive predictive value (PV) of 60%, and negative PV of 94% for identifying large vessel occlusion (LVO) including M1 MCA, terminal internal carotid artery, or tandem ICA/MCA. Thrombolysis in Brain Ischemia scale, with (grade ≥1) compared to without flow (grade 0), showed a sensitivity of 17.1%, specificity of 86.9%, positive PV of 62%, and negative PV of 46% for identifying LVO.

CONCLUSIONS

TCD is a valuable modality for evaluating arterial circulation in acute ischemic stroke patients, demonstrating significant potential as a screening tool for intravenous/intra-arterial lysis protocols.

Clinical applications of ultrasound in neurosurgery and neurocritical care: A narrative review

Ultrasonography (USG) has become an invaluable tool in the assessment of neurocritical patients in the operating theaters and critical care units. Due to its easy availability, reliability, safety, and repeatability, neuro-intensivists and neuro-anesthesiologists utilize USG to make a diagnosis, assess prognosis, and decide upon treatment. In neurocritical care units, USG has myriad indications for use, both systemic and neurologic. The neurological indications include the assessment of stroke, vasospasm, traumatic brain injury, brain death, acute brain damage, optic nerve sheath diameter, and pupillary reflexes to name a few. The systemic indications range from assessment of cardio-pulmonary function and intravascular volume status to detection of deep venous thromboses, vocal cord assessment in intubated patients, placement of central venous catheters, and percutaneous tracheostomy. In this narrative review, we iterate the clinical applications of USG in neuroanesthesia and neurocritical care, which we penned after searching relevant databases in PubMed, Medline, Ovid, and Google Scholar by using terms such as ‘applications of transcranial Doppler’, ‘optic nerve sheath diameter’, ‘USG applications in the critical care unit’, and so on. Our search database includes several research papers, neurocritical care books, review articles, and scientific databases. This article reviews various applications of USG in neuroanesthesia, neurosurgery, and neurocritical care.

Computational modeling of blood clot lysis considering the effect of vessel wall and pulsatile blood flow

Stroke is one of the major causes of global death, which can occur due to blockage in a blood vessel by a clot. The immediate dissolving of the clot is essential to restore the blood flow and prevent tissue necrosis. Clot dissolution can be achieved via thrombolytic therapy using plasminogen activators. In this study, a clot dissolution model is developed for a three-dimensional patient-specific carotid artery that investigates the effect of different vessel wall models on clot dissolution. The lysis pattern of the clot and hemodynamics of blood flow are evaluated using three different models of the vessel wall, namely, rigid, linear elastic, and Mooney-Rivlin hyperelastic. The effect of flow condition is considered by solving the Navier-Stokes equations for the free flow domain and the Brinkman equation for the clot domain with the same pressure and velocity fields. This will result in continuous pressure and velocity over the interfaces of the free flow and clot domains. The blood inflow is assumed to be pulsatile. In addition, the species transport driven by diffusion and convection is considered to be different in the porous medium and plasma. The obtained results show that in all models, the starting time of clot volume decrease is almost the same and the clot starts dissolving from the inner curvature of the artery. However, in the hyperelastic model, dissolving the clot takes longer compared to the other two models. By monitoring the vessel wall deformation, the exact time of vessel recanalization is determined.

In a hub-and-spoke network, spoke-administered thrombolysis reduces mechanical thrombectomy procedure time and number of passes

BACKGROUND

The utility of intravenous thrombolysis (IVT) prior to mechanical thrombectomy (MT) in large vessel occlusion stroke (LVO) is controversial. Some data suggest IVT increases MT technical difficulty. Within our hub-and-spoke telestroke network, we examined how spoke-administered IVT affected hub MT procedure time and pass number.

METHODS

Patients presenting to 25 spoke hospitals who were transferred to the hub and underwent MT from 2018 to 2020 were identified from a prospectively maintained database. MT procedure time, fluoroscopy time, and pass number were obtained from operative reports.

RESULTS

Of 107 patients, 48 received IVT at spokes. Baseline characteristics and NIHSS were similar. The last known well (LKW)-to-puncture time was shorter among IVT patients (4.3 ± 1.9 h vs. 10.5 ± 6.5 h, p < 0.0001). In patients that received IVT, mean MT procedure time was decreased by 18.8 min (50.5 ± 29.4 vs. 69.3 ± 46.7 min, p = 0.02) and mean fluoroscopy time was decreased by 11.3 min (21.7 ± 15.8 vs. 33.0 ± 30.9 min, p = 0.03). Furthermore, IVT-treated patients required fewer MT passes (median 1 pass [IQR 1.0, 1.80] vs. 2 passes [1.0, 2.3], p = 0.0002) and were more likely to achieve reperfusion in ≤2 passes (81.3% vs. 59.3%, p = 0.01). An increased proportion of IVT-treated patients achieved TICI 2b-3 reperfusion after MT (93.9% vs. 83.8%, p = 0.045). There were no associations between MT procedural characteristics and LKW-to-puncture time.

CONCLUSION

Within our network, hub MT following spoke-administered IVT was faster, required fewer passes, and achieved improved reperfusion. This suggests spoke-administered IVT does not impair MT, but instead may enhance it.

TRPM4 Blocking Antibody Protects Cerebral Vasculature in Delayed Stroke Reperfusion

Reperfusion therapy for acute ischemic stroke aims to restore the blood flow of occluded blood vessels. However, successful recanalization is often associated with disruption of the blood-brain barrier, leading to reperfusion injury. Delayed recanalization increases the risk of severe reperfusion injury, including severe cerebral edema and hemorrhagic transformation. The TRPM4-blocking antibody M4P has been shown to alleviate reperfusion injury and improve functional outcomes in animal models of early stroke reperfusion. In this study, we examined the role of M4P in a clinically relevant rat model of delayed stroke reperfusion in which the left middle cerebral artery was occluded for 7 h. To mimic the clinical scenario, M4P or control IgG was administered 1 h before recanalization. Immunostaining showed that M4P treatment improved vascular morphology after stroke. Evans blue extravasation demonstrated attenuated vascular leakage following M4P treatment. With better vascular integrity, cerebral perfusion was improved, leading to a reduction of infarct volume and animal mortality rate. Functional outcome was evaluated by the Rotarod test. As more animals with severe injuries died during the test in the control IgG group, we observed no difference in functional outcomes in the surviving animals. In conclusion, we identified the potential of TRPM4 blocking antibody M4P to ameliorate vascular injury during delayed stroke reperfusion. If combined with reperfusion therapy, M4P has the potential to improve current stroke management.

The role of protein glycosylation in the occurrence and outcome of acute ischemic stroke

Acute ischemic stroke (AIS) is a serious and life-threatening disease worldwide. Despite thrombolysis or endovascular thrombectomy, a sizeable fraction of patients with AIS have adverse clinical outcomes. In addition, existing secondary prevention strategies with antiplatelet and anticoagulant drugs therapy are not able to adequately decrease the risk of ischemic stroke recurrence. Thus, exploring novel mechanisms for doing so represents an urgent need for the prevention and treatment of AIS. Recent studies have discovered that protein glycosylation plays a critical role in the occurrence and outcome of AIS. As a common co- and post-translational modification, protein glycosylation participates in a wide variety of physiological and pathological processes by regulating the activity and function of proteins or enzymes. Protein glycosylation is involved in two causes of cerebral emboli in ischemic stroke: atherosclerosis and atrial fibrillation. Following ischemic stroke, the level of brain protein glycosylation becomes dynamically regulated, which significantly affects stroke outcome through influencing inflammatory response, excitotoxicity, neuronal apoptosis, and blood-brain barrier disruption. Drugs targeting glycosylation in the occurrence and progression of stroke may represent a novel therapeutic idea. In this review, we focus on possible perspectives about how glycosylation affects the occurrence and outcome of AIS. We then propose the potential of glycosylation as a therapeutic drug target and prognostic marker for AIS patients in the future.

Spoke-administered thrombolysis improves large vessel occlusion early recanalization: the real-world experience of a large academic hub-and-spoke telestroke network

Introduction

Intravenous thrombolysis (IVT) prior to mechanical thrombectomy (MT) for large vessel occlusion (LVO) stroke is increasingly controversial. Recent trials support MT without IVT for patients presenting directly to MT-capable "hub" centers. However, bypassing IVT has not been evaluated for patients presenting to IVT-capable "spoke" hospitals that require hub transfer for MT. A perceived lack of efficacy of IVT to result in LVO early recanalization (ER) is often cited to support bypassing IVT, but ER data for IVT in patients that require interhospital transfer is limited. Here we examined LVO ER rates after spoke-administered IVT in our hub-and-spoke stroke network.

Methods

Patients presenting to 25 spokes before hub transfer for MT consideration from 2018-2020 were retrospectively identified from a prospectively maintained database. Inclusion criteria were pre-transfer CTA-defined LVO, ASPECTS ≥6, and post-transfer repeat vessel imaging.

Results

Of 167 patients, median age was 69 and 51% were female. 76 received spoke IVT (+spokeIVT) and 91 did not (-spokeIVT). Alteplase was the only IVT used in this study. Comorbidities and NIHSS were similar between groups. ER frequency was increased 7.2-fold in +spokeIVT patients [12/76 (15.8%) vs. 2/91 (2.2%), P<0.001]. Spoke-administered IVT was independently associated with ER (aOR=11.5, 95% CI=2.2,99.6, p<0.05) after adjusting for timing of last known well, interhospital transfer, and repeat vessel imaging. Interval NIHSS was improved in patients with ER (median -2 (IQR -6.3, -0.8) vs. 0 (-2.5, 1), p<0.05).

Conclusion

Within our network, +spokeIVT patients had a 7.2-fold increased ER relative likelihood. This real-world analysis supports IVT use in eligible patients with LVO at spoke hospitals before hub transfer for MT.

The Sky's the Limit: Expanding Nursing's Contribution to Acute Stroke Science

Stroke is the number one cause of preventable disability in adults in the United States. Significant advances have occurred in medications and technology supporting rapid stroke diagnosis and treatment during the past 30 years, along with blurring of the lines of what traditionally constituted nursing or medical research. Ischemic stroke is a disease of vascular insufficiency that mirrors myocardial infarction more than any other neurologic diagnosis. My primary program of research is focused on exploration of methods to improve intracranial blood flow in patients with hyperacute ischemic stroke who have viable, yet vulnerable, brain tissue to prevent worsening or enable improvement of stroke symptoms. I am also examining augmentation of recombinant tissue plasminogen activator treatment and stimulation of both arteriogenesis and angiogenesis with external counter-pulsation in patients with intracranial atherosclerosis. My secondary program of research focuses on methods to improve stroke systems of care, including improvement of advance practice providers' contributions to acute stroke care, use of innovative mobile stroke units, and improvement of quality core measure processes. Lessons learned along the way are highlighted, along with the value of interdisciplinary "team science" to build knowledge and enhance the care of highly vulnerable patients with acute stroke.

Correlation between the B-type Natriuretic Peptide before thrombolysis and prognosis in patients with ischemic stroke

BACKGROUND AND OBJECTIVE

Elevated levels of B-type natriuretic peptide (BNP) can predict the prognosis of patients with acute ischemic stroke (AIS). However, the association between BNP levels and the clinical outcome in patients with AIS receiving intravenous thrombolysis treatment remains controversial. Therefore, this study aimed to analyse the role of BNP in patients with ischemic stroke who received intravenous recombinant tissue plasminogen activator (rt-PA) therapy.

METHODS

This retrospective study involved 251 patients who were diagnosed with ischemic stroke and had undergone intravenous thrombolysis. The BNP level in blood was assessed before the treatment of thrombolysis. Outcome events include poor functional outcome, and mortality defined as modified Rankin Scale (mRS) scores of 3-6,and 6 respectively.

RESULTS

In multivariate logistic regression, BNP > 78 pg/mL (odds ratio, 2.726 [95% CI, 1.440-5.159]; P = 0.002) was an independent risk factor for 3-month poor outcomes in patients with ischemic stroke treated with thrombolysis, whereas BNP > 103 pg/mL (odds ratio, 4.204 [95% CI, 1.382-12.788]; P = 0.011) was significantly associated with the 3-month mortality. The area under the curve (AUC) of BNP before thrombolysis to predict poor functional outcomes at 3 months were 0.679 (95% CI, 0.618-0.737; P < 0.001), and mortality at 3 months was 0.802 (95% CI, 0.747-0.849; P < 0.001), respectively.

CONCLUSION

An early increase in BNP levels before intravenous thrombolysis was independently associated with 3-month poor outcomes and mortality. Moreover, the pre-thrombolytic BNP level may serve as a more reliable marker for predicting mortality in patients with ischemic stroke.

Frequency and Prognostic Significance of Clinical Fluctuations Before Hospital Arrival in Stroke

BACKGROUND AND PURPOSE

Clinical fluctuations in ischemic stroke symptoms are common, but fluctuations before hospital arrival have not been previously characterized.

METHODS

A standardized qualitative assessment of fluctuations before hospital arrival was obtained in an observational study that enrolled patients with mild ischemic stroke symptoms (National Institutes of Health Stroke Scale [NIHSS] score of 0-5) present on arrival to hospital within 4.5 hours of onset, in a subset of 100 hospitals participating in the Get With The Guidelines-Stroke quality improvement program. The number of fluctuations, direction, and the overall improvement or worsening was recorded based on reports from the patient, family, or paramedics. Baseline NIHSS on arrival and at 72 hours (or discharge if before) and final diagnosis and stroke subtype were collected. Outcomes at 90 days included the modified Rankin Scale, Barthel Index, Stroke Impact Scale 16, and European Quality of Life. Prehospital fluctuations were examined in relation to hospital NIHSS change (admission to 72 hours or discharge) and 90-day outcomes.

RESULTS

Among 1588 participants, prehospital fluctuations, consisting of improvement, worsening, or both were observed in 35.5%: 25.1% improved once, 5.3% worsened once, and 5.1% had more than 1 fluctuation. Those who improved were less likely and those who worsened were more likely to receive alteplase. Those who improved before hospital arrival had lower change in the hospital NIHSS than those who did not fluctuate. Better adjusted 90-day outcomes were noted in those with prehospital improvement compared to those without any fluctuations.

CONCLUSIONS

Fluctuations in neurological symptoms and signs are common in the prehospital setting. Prehospital improvement was associated with better 90-day outcomes, controlling for admission NIHSS and alteplase treatment.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02072681.

Efficacy and safety of bridging thrombolysis initiated before transfer in a drip-and-ship stroke service

Objective

Data regarding the efficacy and safety of bridging thrombolysis (BT) initiated before transfer for evaluation of endovascular therapy is heterogeneous. We, therefore, analyse efficacy and safety of BT in patients treated within a drip-and-ship stroke service.

Methods

Consecutive adult patients suffering from acute ischaemic stroke and large-vessel occlusions (LVO) transferred to our comprehensive stroke centre for evaluation of endovascular therapy in 2017–2020 were identified from a local prospective stroke database and categorised according to BT and no-BT. BT was defined as intravenous thrombolysis initiated before transfer. LVO was assessed before and after transfer. Functional outcome before stroke and at 3 months using the modified Rankin scale (mRS) was determined. Excellent outcome was defined as mRS 0–1 or return to prestroke mRS. For safety analysis, intracranial haemorrhages and mortality at 3 months were analysed. Main analysis was limited to patients with anterior circulation stroke.

Results

Of N=714 patients, n=394 (55.2%) received BT. More patients in the BT group with documented LVO before transfer recanalised without endovascular therapy (n=46, 11.7%) than patients who did not receive BT before transfer (n=4, 1.3%, p<0.001). In multivariate analysis, BT was the strongest independent predictor of early recanalisation (adjusted OR 10.9, 95% CI 3.8 to 31.1, p<0.001). BT tended to be an independent predictor of an excellent outcome at 3 months (adjusted OR 1.38, 95% CI 0.97 to 1.96, p=0.077). There were no differences in safety between the BT and no-BT groups.

Conclusions

BT initiated before transfer was a strong independent predictor of early recanalisation.

Timing of Recanalization and Functional Recovery in Acute Ischemic Stroke

Background and Purpose

Although onset-to-treatment time is associated with early clinical recovery in acute ischemic stroke (AIS) patients treated with intravenous tissue plasminogen activator (tPA), the effect of the timing of tPA-induced recanalization on functional outcomes remains debatable.

Methods

We conducted a multicenter, prospective observational cohort study to determine whether early (within 1-hour from tPA-bolus) complete or partial recanalization assessed during 2-hour real-time transcranial Doppler monitoring is associated with improved outcomes in patients with proximal occlusions. Outcome events included dramatic clinical recovery (DCR) within 2 and 24-hours from tPA-bolus, 3-month mortality, favorable functional outcome (FFO) and functional independence (FI) defined as modified Rankin Scale (mRS) scores of 0–1 and 0–2 respectively.

Results

We enrolled 480 AIS patients (mean age 66±15 years, 60% men, baseline National Institutes of Health Stroke Scale score 15). Patients with early recanalization (53%) had significantly (jos-2019-01648P<0.001) higher rates of DCR at 2-hour (54% vs. 10%) and 24-hour (63% vs. 22%), 3-month FFO (67% vs. 28%) and FI (81% vs. 39%). Three-month mortality rates (6% vs. 17%) and distribution of 3-month mRS scores were significantly lower in the early recanalization group. After adjusting for potential confounders, early recanalization was independently associated with higher odds of 3-month FFO (odds ratio [OR], 6.19; 95% confidence interval [CI], 3.88 to 9.88) and lower likelihood of 3-month mortality (OR, 0.34; 95% CI, 0.17 to 0.67). Onset to treatment time correlated to the elapsed time between tPA-bolus and recanalization (unstandardized linear regression coefficient, 0.13; 95% CI, 0.06 to 0.19).

Conclusions

Earlier tPA treatment after stroke onset is associated with faster tPA-induced recanalization. Earlier onset-to-recanalization time results in improved functional recovery and survival in AIS patients with proximal intracranial occlusions.

Computational simulations of thrombolysis in acute stroke: Effect of clot size and location on recanalisation

Acute ischaemic stroke can be treated by intravenous thrombolysis whereby tissue plasminogen activator (tPA) is infused to dissolve clots that block blood supply to the brain. In this study, we aim to examine the influence of clot location and size on lysis pattern and recanalisation by using a recently developed computational modelling framework for thrombolysis under physiological flow conditions. An image-based patient-specific model is reconstructed which consists of the internal carotid bifurcation with the A1 segment of anterior cerebral arteries and M1 segment of middle cerebral arteries, and the M1 bifurcation containing the M2 segments. By varying the clot size and location, 7 scenarios are simulated mimicking thrombolysis of M1 and M2 occlusions. Our results show that initial breakthrough always occurs along the inner curvature of the occluded cerebral artery, due to prolonged tPA residence time in the recirculation zone. For a given occlusion site, lysis completion time appears to increase almost quadratically with the initial clot volume; whereas for a given clot volume, the simulated M2 occlusions take up to 30% longer for complete lysis compared to the corresponding M1 occlusions.

Is spontaneous normalization of systolic blood pressure within 24 hours after ischemic stroke onset related with favorable outcomes?

Background

In acute ischemic stroke, blood pressure (BP) tends to rise initially and fall to a baseline level within 24–48 hours. Previous studies reported several different effects of BPs during acute ischemic stroke on clinical outcomes, which was partly due to the different time intervals from stroke onset to BP measurement.

Methods

All patients with acute ischemic stroke (onset ≤3 hours) who lived independently before the stroke, were consecutively enrolled for a 62-month period. BPs at 0, 12, and 24 hours after admission were collected. A favorable outcome was defined as a modified Rankin Scale (mRS) score 0–2 at discharge. For different standards of BP management, patients were grouped and analyzed according to intravenous (IV) tissue plasminogen activator (tPA) treatment and favorable outcome.

Results

Among the 446 enrolled patients, 227 patients underwent IV tPA treatment and 216 had mRS score 0–2 at discharge. Patients with favorable outcomes had lower initial NIH Stroke Scale (NIHSS) scores, less frequent progressive neurological deficits, and lower systolic BP (SBP) 12 and 24 hours after admission than patients with unfavorable outcomes, regardless of whether they underwent tPA treatment or not (p <0.05). The BP decreased over a period of 24 hours after admission. In logistic regression analysis, the independent variables associated with favorable outcome were the initial NIHSS score, a progressive neurological deficit, a previous stroke, and the SBP 24 hours after admission in the patients who underwent tPA treatment and the initial NIHSS score and a progressive neurological deficit in the patients who did not undergo tPA treatment (p <0.05).

Conclusions

The SBPs at 12 and 24 hours after admission were lower in acute stroke patients with favorable outcomes than in the other patients, regardless of whether the patients underwent tPA therapy and the SBP at 24 hours was an independent predictor of favorable outcomes among the patients who underwent tPA treatment.

Transcranial diffuse optical assessment of the microvascular reperfusion after thrombolysis for acute ischemic stroke

In this pilot study, we have evaluated bedside diffuse optical monitoring combining diffuse correlation spectroscopy and near-infrared diffuse optical spectroscopy to assess the effect of thrombolysis with an intravenous recombinant tissue plasminogen activator (rtPA) on cerebral hemodynamics in an acute ischemic stroke. Frontal lobes of five patients with an acute middle cerebral artery occlusion were measured bilaterally during rtPA treatment. Both ipsilesional and contralesional hemispheres showed significant increases in cerebral blood flow, total hemoglobin concentration and oxy-hemoglobin concentration during the first 2.5 hours after rtPA bolus. The increases were faster and higher in the ipsilesional hemisphere. The results show that bedside optical monitoring can detect the effect of reperfusion therapy for ischemic stroke in real-time.

Improving Cerebral Blood Flow after Arterial Recanalization: A Novel Therapeutic Strategy in Stroke

Ischemic stroke is caused by a disruption in blood supply to a region of the brain. It induces dysfunction of brain cells and networks, resulting in sudden neurological deficits. The cause of stroke is vascular, but the consequences are neurological. Decades of research have focused on finding new strategies to reduce the neural damage after cerebral ischemia. However, despite the incredibly huge investment, all strategies targeting neuroprotection have failed to demonstrate clinical efficacy. Today, treatment for stroke consists of dealing with the cause, attempting to remove the occluding blood clot and recanalize the vessel. However, clinical evidence suggests that the beneficial effect of post-stroke recanalization may be hampered by the occurrence of microvascular reperfusion failure. In short: recanalization is not synonymous with reperfusion. Today, clinicians are confronted with several challenges in acute stroke therapy, even after successful recanalization: (1) induce reperfusion, (2) avoid hemorrhagic transformation (HT), and (3) avoid early or late vascular reocclusion. All these parameters impact the restoration of cerebral blood flow after stroke. Recent advances in understanding the molecular consequences of recanalization and reperfusion may lead to innovative therapeutic strategies for improving reperfusion after stroke. In this review, we will highlight the importance of restoring normal cerebral blood flow after stroke and outline molecular mechanisms involved in blood flow regulation.

In vivo evaluation of urokinase-loaded hollow nanogels for sonothrombolysis on suture embolization-induced acute ischemic stroke rat model

The urokinase-type plasminogen activator (uPA) loaded hollow nanogels (nUK) were synthesized by a one-step reaction of glycol chitosan and aldehyde capped poly (ethylene oxide). The resultant formulation is sensitive to diagnostic ultrasound (US) of 2 MHz. Herein, we evaluated the in vivo sonothrombolysis performance of the nUK on acute ischemic stroke rat model which was established by suture embolization of middle cerebral artery (MCA). Via intravenous (i.v.) administration, the experimental data prove a controlled release of the therapeutic protein around the clots under ultrasound stimulation, leading to enhanced thrombolysis efficiency of the nUK, evidenced from smaller infarct volume and better clinical scores when compared to the i.v. dose of free uPA no matter with or without US intervention. Meanwhile, the preservation ability of the nanogels not only prolonged the circulation duration of the protein, but also resulted in the better blood-brain barrier protection of the nUK formulation, showing no increased risk on the hemorrhagic transformation than the controls. This work suggests that the nUK is a safe sonothrombolytic formulation for the treatment of acute ischemic stroke.

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Ultrasonic responsive urokinase (uPA)-loaded hollow nanogels (nUK) were synthesized for stroke treatment.

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Acute ischemic stroke rat model was established by suture embolization of middle cerebral artery.

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The nUK enhanced the sonothrombolytic efficacy and led to better BBB protection compared to the free uPA.

Modulation by the Noble Gas Helium of Tissue Plasminogen Activator: Effects in a Rat Model of Thromboembolic Stroke

INTERVENTIONS

Helium has been shown to provide neuroprotection in mechanical model of acute ischemic stroke by inducing hypothermia, a condition shown by itself to reduce the thrombolytic and proteolytic properties of tissue plasminogen activator. However, whether or not helium interacts with the thrombolytic drug tissue plasminogen activator, the only approved therapy of acute ischemic stroke still remains unknown. This point is not trivial since previous data have shown the critical importance of the time at which the neuroprotective noble gases xenon and argon should be administered, during or after ischemia, in order not to block tissue plasminogen activator-induced thrombolysis and to obtain neuroprotection and inhibition of tissue plasminogen activator-induced brain hemorrhages.

MEASUREMENTS AND MAIN RESULTS

We show that helium of 25-75 vol% inhibits in a concentration-dependent fashion the catalytic and thrombolytic activity of tissue plasminogen activator in vitro and ex vivo. In vivo, in rats subjected to thromboembolic brain ischemia, we found that intraischemic helium at 75 vol% inhibits tissue plasminogen activator-induced thrombolysis and subsequent reduction of ischemic brain damage and that postischemic helium at 75 vol% reduces ischemic brain damage and brain hemorrhages.

CONCLUSIONS

In a clinical perspective for the treatment of acute ischemic stroke, these data suggest that helium 1) should not be administered before or together with tissue plasminogen activator therapy due to the risk of inhibiting the benefit of tissue plasminogen activator-induced thrombolysis; and 2) could be an efficient neuroprotective agent if given after tissue plasminogen activator-induced reperfusion.

Application of emerging technologies to improve access to ischemic stroke care

During the past 20 years, the traditional supportive treatment for stroke has been radically transformed by advances in catheter technologies and a cohort of prominent randomized controlled trials that unequivocally demonstrated significant improvement in stroke outcomes with timely endovascular intervention. However, substantial limitations to treatment remain, among the most important being timely access to care. Nonetheless, stroke care has continued its evolution by incorporating technological advances from various fields that can further reduce patients' morbidity and mortality. In this paper the authors discuss the importance of emerging technologies—mobile stroke treatment units, telemedicine, and robotically assisted angiography—as future tools for expanding access to the diagnosis and treatment of acute ischemic stroke.

Early neurological stability predicts adverse outcome after acute ischemic stroke

Background Deterioration in the National Institutes of Health Stroke Scale (NIHSS) in the early days after stroke is associated with progressive infarction, brain edema, and/or hemorrhage, leading to worse outcome. Aims We sought to determine whether a stable NIHSS score represents an adverse or favorable course. Methods Brain magnetic resonance images from a research cohort of acute ischemic stroke patients were analyzed. Using NIHSS scores at baseline and follow-up (day 3-5), patients were categorized into early neurological deterioration (ΔNIHSS ≥ 4), early neurological recovery (ΔNIHSS ≤ -4) or early neurological stability (ΔNIHSS between -3 and 3). The association between these categories and volume of infarct growth, volume of swelling, parenchymal hemorrhage, and 3-month modified Rankin Scale score were evaluated. Results Patients with early neurological deterioration or early neurological stability were less likely to be independent (modified Rankin Scale = 0-2) at 3 months compared to those with early neurological recovery ( P < 0.001). Patients with early neurological deterioration or early neurological stability were observed to have significantly greater infarct growth and swelling volumes than those with early neurological recovery ( P = 0.03; P < 0.001, respectively). Brain edema was more common than the other imaging markers investigated and was independently associated with a stable or worsening NIHSS score after adjustment for age, baseline stroke volume, infarct growth volume, presence of parenchymal hemorrhage, and reperfusion ( P < 0.0001). Conclusions Stable NIHSS score in the subacute period after ischemic stroke may not be benign and is associated with tissue injury, including infarct growth and brain edema. Early improvement is considerably more likely to occur in the absence of these factors.

Meta-analysis of Vascular Imaging Features to Predict Outcome Following Intravenous rtPA for Acute Ischemic Stroke

Background

The present review investigated which findings in vascular imaging techniques can be used to predict clinical outcome and the risk of symptomatic intracerebral hemorrhage (sICH) in patients who underwent intravenous thrombolytic treatment.

Methods

Publications were searched, and the inclusion criteria were as follows: (1) published manuscripts, (2) patients with acute ischemic stroke managed with intravenous recombinant tissue plasminogen activator (rtPA), and (3) availability of imaging assessment to determine vessel patency or the regulation of cerebral blood flow prior to, during, and/or after thrombolytic treatment. Clinical outcomes were divided into neurological outcome [National Institutes of Health Stroke Scale (NIHSS) within 7 days] and functional outcome (modified Rankin score in 2–3 months). sICH was defined as rtPA-related intracerebral bleeding associated with any worsening of NIHSS.

Results

Thirty-nine articles were selected. Recanalization was associated with improved neurological and functional outcomes (OR = 7.83; 95% CI, 3.71–16.53; p < 0.001 and OR = 11.12; 95% CI, 5.85–21.14; p < 0.001, respectively). Both tandem internal carotid artery/middle cerebral artery (ICA/MCA) occlusions and isolated ICA occlusion had worse functional outcome than isolated MCA occlusion (OR = 0.26, 95% CI, 0.12–0.52; p < 0.001 and OR = 0.24, 95% CI, 0.07–0.77; p = 0.016, respectively). Reocclusion was associated with neurological deterioration (OR = 6.48, 95% CI, 3.64–11.56; p < 0.001), and early recanalization was associated with lower odds of sICH (OR = 0.36, 95% CI, 0.18–0.70; p = 0.003).

Conclusion

Brain circulation data before, during, and after thrombolysis may be useful for predicting the clinical outcome. Cerebral arterial recanalization, presence and site of occlusion, and reocclusion are all important in predicting the clinical outcome.

Factors Associated with Thrombolysis Outcome in Ischemic Stroke Patients with Atrial Fibrillation

The outcome of early intravenous thrombolysis for ischemic stroke in patients with atrial fibrillation (AF) is worse than that without thrombosis. How to increase the efficacy of intravenous thrombolysis for AF-related ischemic stroke remains largely unknown. In this study, we investigated factors that influence the effect of intravenous thrombolysis in these patients. Our results showed that thrombolysis was independently associated with a favorable outcome (P < 0.001) and did not influence the mortality of AF-related ischemic stroke, although it increased the risk of hemorrhage within 24 h after treatment. Risk factors for a poor outcome at admission were: heart failure (P = 0.045); high systolic pressure (P = 0.039); high blood glucose (P = 0.030); and a high National Institutes of Health Stroke Scale (NIHSS) score (P < 0.001). Moreover, high systolic pressure at admission (P = 0.007), high blood glucose (P = 0.027), and a high NIHSS score (P < 0.001) were independent risk factors for mortality at 3 months. Besides thrombolysis, a high NIHSS score (P = 0.006) and warfarin taken within 48 h before stroke onset (P = 0.032) were also independent risk factors for symptomatic hemorrhage within 24 h after treatment. Ischemic stroke patients with AF benefited from intravenous thrombolysis with recombinant tissue plasminogen activator within 4.5 h after stroke.

Atrial Fibrillation is Associated With Poor Outcomes in Thrombolyzed Patients With Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

The influence of atrial fibrillation (AF) on the clinical outcomes of patients with ischemic stroke (IS) has not been completely determined. We aimed to perform a systematic review and meta-analysis to assess the relationship between AF and adverse events in patients with acute IS treated with thrombolysis.PubMed, EMBASE, and the Cochrane Library were searched for relevant studies regarding the association between AF and the outcomes of patients with IS treated with thrombolysis. Random and fixed effect models were used for pooling data.Twelve cohort studies involving 14,801 patients with acute IS were included. Meta-analysis revealed that patients with AF were more likely to die within 90 days after thrombolysis (odds ratio [OR], 2.13; 95% confidence interval [CI]: 1.68-2.70, P < 0.001), whereas this association was not observed in hospitalized patients (OR, 1.50; 95% CI, 0.86-2.60; P = 0.150). AF was associated with a reduced incidence of favorable outcomes (modified Rankin Scale ≤ 2) (OR, 1.95; 95% CI: 1.33-2.85, P = 0.001) and an increased risk of symptomatic intracerebral hemorrhage (OR, 1.28; 95% CI: 1.08-1.52, P = 0.006). No evident publication bias was found by Begg's test or Egger's test.Comorbidity of AF may increase the risk of adverse outcomes for patients with IS undergoing thrombolysis. Further well-designed trials are warranted to confirm this association.

Transcranial Doppler Ultrasound: Physical Principles and Principal Applications in Neurocritical Care Unit

Transcranial Doppler (TCD) ultrasonography is a noninvasive ultrasound study, which has been extensively applied on both outpatient and inpatient settings. It involves the use of a low-frequency (≤2 MHz) transducer, placed on the scalp, to insonate the basal cerebral arteries through relatively thin bone windows and to measure the cerebral blood flow velocity and its alteration in many different conditions. In neurointensive care setting, TCD is useful for both adults and children for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoid hemorrhage, traumatic brain injury, acute ischemic stroke, and brain stem death. It also allows to investigate the cerebrovascular autoregulation in setting of carotid disease and syncope. In this review, we will describe physical principles underlying TCD, flow indices most frequently used in clinical practice and critical care applications in Neurocritical Unit care.

Vascular imaging: ultrasound

The complexity of current stroke treatments requires detailed vascular imaging information. Vascular imaging using ultrasound is a safe, inexpensive, and portable technique that provides continuous real-time hemodynamic information, which allows flow changes to be monitored over prolonged time. Ultrasound imaging is in continuous development, which has led to a growing number of situations where ultrasound can be helpful, foremost in dynamic and rapidly changing clinical scenarios like acute stroke. The aim of this chapter is to review the main indications of vascular ultrasound in acute stroke, including extracranial steno-occlusive lesions diagnosis and its consequences on distal vasculature, intracranial stenosis diagnosis, acute intracranial occlusion, recanalization, and reocclusion diagnosis and monitoring, therapeutic sonothrombolysis, and vasospasm after subarachnoid hemorrhage.

Critical early thrombolytic and endovascular reperfusion therapy for acute ischemic stroke victims: a call for adjunct neuroprotection

Today, there is an enormous amount of excitement in the field of stroke victim care due to the recent success of MR. CLEAN, SWIFT PRIME, ESCAPE, EXTEND-IA, and REVASCAT endovascular trials. Successful intravenous (IV) recombinant tissue plasminogen activator (rt-PA) clinical trials [i.e., National Institute of Neurological Disorders and Stroke (NINDS) rt-PA trial, Third European Cooperative Acute Stroke Study (ECASSIII), and Third International Stroke study (IST-3)] also need to be emphasized. In the recent endovascular and thrombolytic trials, there is statistically significant improvement using both the National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Score (mRS) scale, but neither approach promotes complete recovery in patients enrolled within any particular NIHSS or mRS score tier. Absolute improvement (mRS 0-2 at 90 days) with endovascular therapy is 13.5-31 %, whereas thrombolytics alone also significantly improve patient functional independence, but to a lesser degree (NINDS rt-PA trial 13 %). This article has 3 main goals: (1) first to emphasize the utility and cost-effectiveness of rt-PA to treat stroke; (2) second to review the recent endovascular trials with respect to efficacy, safety, and cost-effectiveness as a stroke treatment; and (3) to further consider and evaluate strategies to develop novel neuroprotective drugs. A thesis will be put forth so that future stroke trials and therapy development can optimally promote recovery so that stroke victims can return to "normal" life.

Revisiting Cerebral Postischemic Reperfusion Injury: New Insights in Understanding Reperfusion Failure, Hemorrhage, and Edema

Cerebral postischemic reperfusion injury is defined as deterioration of ischemic brain tissue that parallels and antagonizes the benefits of restoring cerebral circulation after therapeutic thrombolysis for acute ischemic stroke. To understand the paradox of injury caused by treatment, we first emphasize the phenomenon in which recanalization of an occluded artery does not lead to tissue reperfusion. Additionally, no-reflow after recanalization may be due to injury of the neurovascular unit, distal microthrombosis, or both, and certainly worsens outcome. We examine the mechanism of molecular and sub-cellular damage in the neurovascular unit, notably oxidative stress, mitochondrial dysfunction, and apoptosis. At the level of the neurovascular unit, which mediates crosstalk between the damaged brain and systemic responses in blood, we summarize emerging evidence demonstrating that individual cell components play unique and cumulative roles that lead to damage of the blood–brain barrier and neurons. Furthermore, we review the latest developments in establishing a link between the immune system and microvascular dysfunction during ischemic reperfusion. Progress in assessing reperfusion injury has also been made, and we review imaging studies using various magnetic resonance imaging modalities. Lastly, we explore potential treatment approaches, including ischemic preconditioning, postconditioning, pharmacologic agents, and hypothermia.

Incidence, causes and predictors of neurological deterioration occurring within 24 h following acute ischaemic stroke: a systematic review with pathophysiological implications

Early neurological deterioration (END) following ischaemic stroke is a serious event with manageable causes in only a fraction of patients. The incidence, causes and predictors of END occurring within 24 h of acute ischaemic stroke (END24) have not been systematically reviewed. We systematically reviewed Medline and Embase from January 1990 to April 2013 for all studies on END24 following acute ischaemic stroke (<8 h from onset). We recorded the incidence and presumed causes of and factors associated with END24. Thirty-six studies were included. Depending on the definition used, the incidence of END24 markedly varied among studies. Using the most widely used change in National Institutes of Health Stroke Scale ≥4 definition, the pooled incidence was 13.8% following thrombolysis, ascribed to intracranial haemorrhage and malignant oedema each in ∼20% of these. As other mechanisms were rarely reported, in the majority no clear cause was identified. Few data on END24 occurring in non-thrombolysed patients were available. Across thrombolysed and non-thrombolysed samples, the strongest and most consistent admission predictors were hyperglycaemia, no prior aspirin use, prior transient ischaemic attacks, proximal arterial occlusion and presence of early CT changes, and the most consistent 24 h follow-up associated factors were no recanalisation/reocclusion, large infarcts and intracranial haemorrhage. Finally, END24 was strongly predictive of poor outcome. The above findings are discussed with emphasis on END without a clear mechanism. Data on incidence and predictors of the latter subtype is scarce, and future studies using systematic imaging protocols should address its underlying pathophysiology. This may in turn lead to rational preventative and therapeutic measures for this ominous event.

Reduction in IV t-PA Door to Needle Times Using an Acute Stroke Triage Pathway

Objective:

To determine the effectiveness of an Acute Stroke Triage Pathway in reducing door to needle times in acute stroke treatment with IV t-PA.

Background:

A previous study at our tertiary referral centre, examining IV t-PA door to needle times, was completed in 2000. The median door to needle time was beyond the recommended National Institute for Neurological Disorders and Stroke (NINDS) standard of 60 minutes. In November 2001, an Acute Stroke Triage Pathway was introduced in the emergency room (ER) to address this issue. The goal of this pathway was to rapidly identify patients eligible for treatment for IV t-PA, so that CT scans and lab studies could be arranged immediately upon ER arrival. Our hypothesis was that the Triage Pathway would shorten door to CT and door to needle times.

Design/Methods:

Using retrospective data, pre (n=87) and post (n=47) triage pathway times were compared. The door to CT time was reduced by 11 minutes (p=0.015) and door to needle time was reduced by 18 minutes (p=0.0036) in a subgroup of patients that presented directly to our hospital.

Conclusions:

These results indicate that the Acute Stroke Triage Pathway is effective in reducing Door to CT and Door to Needle Times in patients presenting directly to our ER. However, a majority of treatment times were still beyond NINDS recommendations. Stroke Centers require periodic review of their efficiency to ensure that target times are being obtained and may benefit from the use of an Acute Stroke Triage Pathway.

A comparison of rt-PA thrombolysis guidelines between China and the USA: are changes needed?

BACKGROUND AND PURPOSE

Thrombolytic treatment criteria vary significantly between China and the USA. We reviewed current intravenous (IV) thrombolytic therapy practices in China and the USA to determine the most appropriate.

METHODS

We conducted a systematic review of studies that used IV recombinant tissue plasminogen activator (rt-PA) therapy in China and the USA published between January 1950 and April 2012.

RESULTS

Literature search identified 17 American and 9 Chinese studies with a total of 2545 subjects. We found a significantly lower mortality rate in the US data compared with China (8% versus 13%; Chi-square  =  24.412, P < 0.001). Our meta-regression analysis uncovered significant factors influencing mortality including male sex, hypertension, high cholesterol, smoking, and onset to treatment time (all P < 0.05). There were significantly more favorable outcomes in China than in the USA (61% versus 49%, Chi-square  =  19.159, P < 0.001). No prior history of stroke and shorter onset to IV time were also significantly associated with a favorable outcome (P < 0.05).

CONCLUSIONS

Onset to IV time is critical for reducing mortality and improving favorable outcomes. We suggest Chinese acute ischemic stroke treatment guidelines be revised to include an increase in the age limit of 80 years, removing contraindications such as a history of previous sever heart, liver, and kidney dysfunction, and placing more emphasis on physician expertise.

Time to angiographic reperfusion and clinical outcome after acute ischaemic stroke: an analysis of data from the Interventional Management of Stroke (IMS III) phase 3 trial

BACKGROUND

The IMS III trial did not show a clinical benefit of endovascular treatment compared with intravenous alteplase (recombinant tissue plasminogen activator) alone for moderate or severe ischaemic strokes. Late reperfusion of tissue that was no longer salvageable could be one explanation, as suggested by previous exploratory studies that showed an association between time to reperfusion and good clinical outcome. We sought to validate this association in a preplanned analysis of data from the IMS III trial.

METHODS

We used data for patients with complete proximal arterial occlusions in the anterior circulation who received endovascular treatment and achieved angiographic reperfusion (score on Thrombolysis in Cerebral Infarction scale of grade 2-3) during the endovascular procedure (within 7 h of symptom onset). We used logistic regression to model good clinical outcome (defined as a modified Rankin Scale score of 0-2 at 3 months) as a function of the time to reperfusion. We prespecified variables to be considered for adjustment, including age, baseline National Institutes of Health Stroke Scale score, sex, and baseline blood glucose concentration.

FINDINGS

Of 240 patients who were otherwise eligible for inclusion in our analysis, 182 (76%) achieved angiographic reperfusion. Mean time from symptom onset to reperfusion (ie, procedure end) was 325 min (SD 52). Increased time to reperfusion was associated with a decreased likelihood of good clinical outcome (unadjusted relative risk for every 30-min delay 0·85 [95% CI 0·77-0·94]; adjusted relative risk 0·88 [0·80-0·98]).

INTERPRETATION

Delays in time to angiographic reperfusion lead to a decreased likelihood of good clinical outcome in patients after moderate to severe stroke. Rapid reperfusion could be crucial for the success of future acute endovascular trials.

FUNDING

US National Institutes of Health and National Institute of Neurological Disorders and Stroke.

Does the sex of acute stroke patients influence the effectiveness of rt-PA?

BACKGROUND

Women have been reported to show more frequent recanalization and better recovery after intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment for acute stroke compared with men. To investigate this we studied a series of stroke patients receiving IV rt-PA and undergoing acute transcranial doppler (TCD) examination.

METHODS

Acute stroke patients received IV rt-PA and had acute TCD examination within 4 hours of symptom onset at 4 major stroke centers. TCD findings were interpreted using the Thrombolysis in Brain Ischemia (TIBI) flow grading system. The recanalization rates, and poor 3-month outcomes (modified Rankin scale >2) of men and women were compared using the chi-square test. Multiple regression analysis was used to assess sex as a predictor of recanalization and poor 3-month outcome after controlling for age, baseline NIH Stroke Scale (NIHSS), time to treatment, hypertension, and blood glucose.

RESULTS

369 patients had TCD examinations before or during IV rt-PA treatment. The 199 (53.9%) men and 170 (46.1%) women had mean ages of 67 ± 13 and 70 ± 14 years, respectively. The sexes did not differ significantly in baseline stroke severity, time to TCD examination, or time to thrombolysis. Of the men, 68 (34.2%) had complete recanalization, 58 (29.1%) had partial recanalization, and 73 (36.6%) had no recanalization. Of the women, 53 (31.2%) had complete recanalization, 46 (27%) had partial recanalization, and 71 (41.8%) had no recanalization (p = 0.6). Multiple regression analyses showed no difference between the sexes in recanalization rate, time to recanalization, or clinical outcome at 3 months.

CONCLUSIONS

In our study; sex is not a significant predictor of recanalization rate, time to recanalization or 3-month outcome in stroke patients following IV rt-PA.

TRIAL REGISTRATION

Data from CLOTBUST trial Clinicaltrials.gov Identifier: NCT01240356.

The Role of Endovascular Therapy in the Treatment of Acute Ischemic Stroke

Of the approximately 795 000 strokes in the United States annually, 87% are ischemic and result in significant morbidity and mortality. Improvements in acute ischemic stroke (AIS) outcomes have been achieved with intravenous thrombolytics (IVT) and intra-arterial thrombolytics vs supportive medical therapy. Given its ease of administration, noninvasiveness, and most validated efficacy, IVT is the standard of care in AIS patients without contraindications to systemic fibrinolysis. However, patients with large-vessel occlusions respond poorly to IVT. Recent trials designed to select this population for randomization to IVT vs IVT with adjunctive endovascular therapy have not shown improvement in clinical outcomes with endovascular therapy. This could be due to the lack of utilization of modern thrombectomy devices such as Penumbra aspiration devices, Solitaire stent-trievers, or Trevo stent-trievers, which have shown the best recanalization results. Continued improvement in the techniques with using these devices as well as randomized controlled trials using them is warranted. This article defines the goals of AIS revascularization, presents the evolution of treatment from the initial use of IVT to modern thrombectomy devices, and discusses current treatment and ongoing AIS trials.

Monitoring and imaging the clot during systemic thrombolysis in stroke patients

Intravenous thrombolysis is the only approved treatment for acute ischemic stroke when administered within the first 3 h of stroke onset. Response to systemic thrombolysis depends on several factors including the location of arterial occlusion, clot characteristics and, ultimately, the embolic source. In the last few years, tremendous progress has been made, resulting in the widespread implementation of noninvasive neurovascular techniques. These imaging modalities are being increasingly performed in the acute stroke setting, without substantial delay, in a large number of centers worldwide. Transcranial Doppler ultrasound provides a unique opportunity to assess several aspects of clot dissolution by means of continuous monitoring of recanalization during and after tissue plasminogen activator administration. This approach allows for the evaluation of patients at the bedside and in real time due to the commencement, timing, speed and degree of artery reopening in addition to allowing the documentation of reocclusion after successful recanalization. Gradient refocused echo susceptibility vessel sign (GRE SVS) magnetic resonance imaging may be particularly useful for the identification of an intravascular thrombus during the acute phase of ischemic stroke; GRE SVS may represent a surrogate of clot composition and differential response to thrombolysis. The increasing availability of advanced neurovascular techniques may, in the near future, improve the design of stroke trials. The capability of these techniques to assess not only tissue viability but also key aspects regarding susceptibility to thrombolysis such as location, amount, composition, and age of the offending clot may improve the safety and efficacy profile of thrombolytic therapy for acute ischemic stroke.

Transcranial Doppler ultrasound: a review of the physical principles and major applications in critical care

Transcranial Doppler (TCD) is a noninvasive ultrasound (US) study used to measure cerebral blood flow velocity (CBF-V) in the major intracranial arteries. It involves use of low-frequency (≤2 MHz) US waves to insonate the basal cerebral arteries through relatively thin bone windows. TCD allows dynamic monitoring of CBF-V and vessel pulsatility, with a high temporal resolution. It is relatively inexpensive, repeatable, and portable. However, the performance of TCD is highly operator dependent and can be difficult, with approximately 10-20% of patients having inadequate transtemporal acoustic windows. Current applications of TCD include vasospasm in sickle cell disease, subarachnoid haemorrhage (SAH), and intra- and extracranial arterial stenosis and occlusion. TCD is also used in brain stem death, head injury, raised intracranial pressure (ICP), intraoperative monitoring, cerebral microembolism, and autoregulatory testing.

The exact science of stroke thrombolysis and the quiet art of patient selection

The science of metric-based patient stratification for intravenous thrombolysis, revolutionized by the landmark National Institute of Neurological Disorders and Stroke trial, has transformed acute ischaemic stroke therapy. Recanalization of an occluded artery produces tissue reperfusion that unequivocally improves outcome and function in patients with acute ischaemic stroke. Recanalization can be achieved mainly through intravenous thrombolysis, but other methods such as intra-arterial thrombolysis or mechanical thrombectomy can also be employed. Strict guidelines preclude many patients from being treated by intravenous thrombolysis due to the associated risks. The quiet art of informed patient selection by careful assessment of patient baseline factors and brain imaging could increase the number of eligible patients receiving intravenous thrombolysis. Outside of the existing eligibility criteria, patients may fall into therapeutic 'grey areas' and should be evaluated on a case by case basis. Important factors to consider include time of onset, age, and baseline blood glucose, blood pressure, stroke severity (as measured by National Institutes of Health Stroke Scale) and computer tomography changes (as measured by Alberta Stroke Programme Early Computed Tomography Score). Patients with traditional contraindications such as wake-up stroke, malignancy or dementia may have the potential to receive benefit from intravenous thrombolysis if they have favourable predictors of outcome from both clinical and imaging criteria. A proportion of patients experience complications or do not respond to intravenous thrombolysis. In these patients, other endovascular therapies or a combination of both may be used to provide benefit. Although an evidence-based approach to intravenous thrombolysis for acute ischaemic stroke is pivotal, it is imperative to examine those who might benefit outside of protocol-driven practice.

Stroke Outcomes in Thai Elderly Patients Treated with and without Intravenous Thrombolysis

Higher mortality was found in very old patients with acute ischemic stroke treated with intravenous recombinant tissue-plasminogen activator (rtPA) as compared to younger patients. The benefit of thrombolytic treatment in this particular subgroup is still a subject of debate. The purpose of this study was to compare stroke outcomes in Thai patients aged over 70 years treated with and without intravenous rtPA. This was a retrospective review of sequential cases and was not a randomized controlled study. One-hundred and five patients with acute ischemic stroke aged over 70 years who were treated with intravenous rtPA and 105 patients without rtPA treatment (control group) were included in the study. Patients’ base-line characteristics and study outcomes of interest were compared. There were significant differences in the base-line characteristics of the two groups. However, for the subgroup of patients aged over 80 years, these characteristics were similar. Those who were treated with intravenous rtPA had a higher rate of favorable outcomes (40% vs 16%; P=0.137) and a lower rate of mortality (22% vs 44%; P=0.128) than patients who did not receive rtPA treatment. In well-matched subgroups of patients aged over 80 years, our retrospective review revealed there was a trend of a higher rate of favorable outcome and lower mortality in patients receiving rtPA treatment. More study is needed to further confirm the suggested benefit of thrombolysis in Asian octogenarian acute stroke patients.

Early and continuous neurologic improvements after intravenous thrombolysis are strong predictors of favorable long-term outcomes in acute ischemic stroke

BACKGROUND

Intravenously administered tissue plasminogen activator (IV tPA) remains the only approved therapeutic agent for arterial recanalization in acute ischemic stroke (AIS). Considerable proportion of AIS patients demonstrate changes in their neurologic status within the first 24 hours of intravenous thrombolysis with IV tPA. However, there are little available data on the course of clinical recovery in subacute 2- to 24-hour window and its impact. We evaluated whether neurologic improvement at 2 and 24 hours after IV tPA bolus can predict functional outcomes in AIS patients at 3 months.

METHODS

Data for consecutive AIS patients treated with IV tPA within 4.5 hours of symptom onset during 2007-2011 were prospectively entered in our thrombolyzed registry. National Institutes of Health Stroke Scale (NIHSS) scores were recorded before IV tPA bolus, at 2 and 24 hours. Early neurologic improvement (ENI) at 2 hours was defined as a reduction in NIHSS score by 10 or more points from baseline or an absolute score of 4 or less points at 2 hours. Continuous neurologic improvement (CNI) was defined as a reduction of NIHSS score by 8 or more points between 2 and 24 hours or an absolute score of 4 or less points at 24 hours. Favorable functional outcomes at 3 months were determined by modified Rankin Scale (mRS) score of 0-1.

RESULTS

Of 2460 AIS patients admitted during the study period, 263 (10.7%) received IV tPA within the time window; median age was 64 years (range 19-92), with 63.9% being men, a median NIHSS score of 17 points (range 5-35), and a median onset-to-treatment time of 145 minutes (range 57-270). Overall, 130 (49.4%) thrombolyzed patients achieved an mRS score of 0-1 at 3 months. The female gender, age, and baseline NIHSS score were found to be significantly associated with CNI on univariate analysis. On multivariate analysis, NIHSS score at onset and female gender (odds ratio [OR]: 2.218, 95% confidence interval [CI]: 1.140-4.285; P=.024) were found to be independent predictors of CNI. Factors associated with favorable outcomes at 3 months on univariate analysis were younger age, female gender, hypertension, NIHSS score at onset, recanalization on transcranial Doppler (TCD) monitoring or repeat computed tomography (CT) angiography, ENI at 2 hours, and CNI. On multivariate analysis, NIHSS score at onset (OR per 1-point increase: .835, 95% CI: .751-.929, P<.001), 2-hour TCD recanalization (OR: 3.048, 95% CI: 1.537-6.046; P=.001), 24-hour CT angiographic recanalization (OR: 4.329, 95% CI: 2.382-9.974; P=.001), ENI at 2 hours (OR: 2.536, 95% CI: 1.321-5.102; P=.004), and CNI (OR: 7.253, 95% CI: 3.682-15.115; P<.001) were independent predictors of favorable outcomes at 3 months.

CONCLUSIONS

Women are twice as likely to have CNI from the 2- to 24-hour period after IV tPA. ENI and CNI within the first 24 hours are strong predictors of favorable functional outcomes in thrombolyzed AIS patients.

Prevention of rt-PA induced blood-brain barrier component degradation by the poly(ADP-ribose)polymerase inhibitor PJ34 after ischemic stroke in mice

Recombinant tissue plasminogen activator (rt-PA) is the only pharmacological treatment approved for thrombolysis in patients suffering from ischemic stroke, but its administration aggravates the risk of hemorrhagic transformations. Experimental data demonstrated that rt-PA increases the activity of poly(ADP-ribose)polymerase (PARP). The aim of the present study was to investigate whether PJ34, a potent (PARP) inhibitor, protects the blood-brain barrier components from rt-PA toxicity. In our mouse model of cerebral ischemia, administration of rt-PA (10 mg/kg, i.v.) 6h after ischemia aggravated the post-ischemic degradation of ZO-1, claudin-5 and VE-cadherin, increased the hemorrhagic transformations (assessed by brain hemoglobin content and magnetic resonance imaging). Furthermore, rt-PA also aggravated ischemia-induced functional deficits. Combining PJ34 with rt-PA preserved the expression of ZO-1, claudin-5 and VE-cadherin, reduced the hemorrhagic transformations and improved the sensorimotor performances. In vitro studies also demonstrated that PJ34 crosses the blood-brain barrier and may thus exert its protective effect by acting on endothelial and/or parenchymal cells. Thus, co-treatment with a PARP inhibitor seems to be a promising strategy to reduce rt-PA-induced vascular toxicity after stroke.

Impact of diffusion-weighted imaging lesion volume on the success of endovascular reperfusion therapy

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) lesion volume is associated with poor outcome after thrombolysis, and it is unclear whether endovascular therapies are beneficial for large DWI lesion. Our aim was to assess the impact of pretreatment DWI lesion volume on outcomes after endovascular therapy, with a special emphasis on patients with complete recanalization.

METHODS

We analyzed data collected between April 2007 and November 2011 in a prospective clinical registry. All acute ischemic stroke patients with complete occlusion of internal carotid artery or middle cerebral artery treated by endovascular therapy were included. DWI lesion volumes were measured by the RAPID software. Favorable outcome was defined by modified Rankin Scale of 0 to 2 at 90 days.

RESULTS

A total of 139 acute ischemic stroke patients were included. Median DWI lesion volume was 14 cc (interquartile range, 5-43) after a median onset time to imaging of 110 minutes (interquartile range, 77-178). Higher volume was associated with less favorable outcome (adjusted odds ratio, 0.55; 95% confidence interval, 0.31-0.96). A complete recanalization was achieved in 65 (47%) patients after a median onset time of 238 minutes (interquartile range, 206-285). After adjustment for volume, complete recanalization was associated with more favorable outcome (adjusted odds ratio, 6.32; 95% confidence interval, 2.90-13.78). After stratification of volume by tertiles, complete recanalization was similarly associated with favorable outcome in the upper 2 tertiles (P<0.005).

CONCLUSIONS

Our results emphasize the importance of initial DWI volume and recanalization on clinical outcome after endovascular treatment. Large DWI lesions may still benefit from recanalization in selected patients.