Thrombolytic therapy for ischemic stroke--a review. Part II--Intra-arterial thrombolysis, vertebrobasilar stroke, phase IV trials, and stroke imaging

Stroke: Evolution of newer treatment modalities for acute ischemic stroke

Acute ischemic stroke is one of the leading causes of morbidity and mortality worldwide. Restoration of cerebral blood flow to affected ischemic areas has been the cornerstone of therapy for patients for eligible patients as early diagnosis and treatment have shown improved outcomes. However, there has been a paradigm shift in the management approach over the last decade, and with the emphasis currently directed toward including newer modalities such as neuroprotection, stem cell treatment, magnetic stimulation, anti-apoptotic drugs, delayed recanalization, and utilization of artificial intelligence for early diagnosis and suggesting algorithm-based management protocols.

CNB-001, a pleiotropic drug is efficacious in embolized agyrencephalic New Zealand white rabbits and ischemic gyrencephalic cynomolgus monkeys

Ischemic stroke is an acute neurodegenerative disease that is extremely devastating to patients, their families and society. Stroke is inadequately treated even with endovascular procedures and reperfusion therapy. Using an extensive translational screening process, we have developed a pleiotropic cytoprotective agent with the potential to positively impact a large population of brain ischemia patients and revolutionize the process used for the development of new drugs to treat complex brain disorders. In this unique translational study article, we document that the novel curcumin-based compound, CNB-001, when administered as a single intravenous dose, has significant efficacy to attenuate clinically relevant behavioral deficits following ischemic events in agyrencephalic rabbits when administered 1 h post-embolization and reduces infarct growth in gyrencephalic non-human primates, when administered 5 min after initiation of middle cerebral artery occlusion. CNB-001 is safe and does not increase morbidity or mortality in either research species. Mechanistically, CNB-001 inhibits human 5- and 15-lipoxygenase in vitro, and can attenuate ischemia-induced inflammatory markers, and oxidative stress markers, while potentially promoting synaptic plasticity mediated by enhanced brain-derived neurotrophic factor (BDNF).

Acute Ischaemic Stroke: Management, Recent Advances and Controversies

Acute ischaemic stroke is a major cause of death and disability. It may become an enormous burden to the patients themselves, their families as well as the health care systems. Patients at risk of airway, breathing and circulatory compromise should receive prompt resuscitation. Vital parameters and neurological status should be closely monitored. Attentions to blood pressure, temperature and sugar profile are important. The significance of early and correct diagnosis and subsequent treatment cannot be over-emphasised. There have been tremendous recent advances in different treatment modalities in acute stroke management. Various recanalisation modalities include intravenous and/or intra-arterial thrombolysis, acute defibrinogenation, anti-platelet treatment and anticoagulation. Carotid endarterectomy and endovascular strategies are recommended in selected patients. Advanced neuro-imaging techniques and neuroprotectants are being evaluated. Multidisciplinary stroke teams have been shown to improve patient survival and functional outcome. Pre-defined algorithms and protocols should be in place to expedite smooth and effective delivery of stroke service. Future directions should be aimed at exploring safer recanalisation modalities and extending the limit of the current 3-hour treatment window for thrombolysis.

Cytoprotective Drug-Tissue Plasminogen Activator Protease Interaction Assays: Screening of Two Novel Cytoprotective Chromones

Tissue plasminogen activator (tPA) is currently used in combination with endovascular procedures to enhance recanalization and cerebral reperfusion and is also currently administered as standard-of-care thrombolytic therapy to patients within 3-4.5 h of an ischemic stroke. Since tPA is not neuroprotective or cytoprotective, adjuvant therapy with a neuroprotective or an optimized cytoprotective compound is required to provide the best care to stroke victims to maximally promote clinical recovery. In this article, we describe the use of a sensitive standardized protease assay with CH3SO2-D-hexahydrotyrosine-Gly-Arg-p-nitroanilide•AcOH, a chromogenic protease substrate that is cleaved to 4-nitroaniline (p-nitroaniline) and measured spectrophotometrically at 405 nm (OD405 nm), and how the assay can be used as an effective screening assay to study drug-tPA interactions. While we focus on two compounds of interest in our drug development pipeline, the assay is broadly applicable to all small molecule neuroprotective or cytoprotective compounds currently being discovered and developed worldwide. In this present study, we found that the specific tPA inhibitor, plasminogen activator inhibitor-1 (PAI-1; 0.25 μM), significantly (p < 0.0001) inhibited 4-nitroaniline release, by 97.74% during the 10-min duration of the assay, which is indicative of tPA protease inhibition. In addition, two lead chromone cytoprotective candidates, 2-(3',4',5'-trihydroxyphenyl)chromen-4-one (3',4',5'-trihydroxyflavone) (CSMC-19) and 3-hydroxy-2-[3-hydroxy-4-(pyrrolidin-1-yl)phenyl]benzo[h]chromen-4-one (CSMC-140), also significantly (p < 0.05) reduced 4-nitroaniline accumulation, but to a lesser extent. The reduction was 68 and 45%, respectively, at 10 μM, and extrapolated IC50 values were 4.37 and >10 μM for CSMC-19 and CSMC-140, respectively. Using bonafide 4-nitroaniline, we then demonstrated that the reduction of 4-nitroaniline detection was not due to drug-4-nitroaniline quenching of signal detection at OD405 nm. In conclusion, the results suggest that high concentrations of both cytoprotectives reduced 4-nitroaniline production in vitro, but the inhibition only occurs with concentrations 104-1025-fold that of EC50 values in an efficacy assay. Thus, CSMC-19 and CSMC-140 should be further developed and evaluated in embolic stroke models in the absence or presence of a thrombolytic. If necessary, they could be administered once effective tPA thrombolysis has been confirmed to avoid the possibility that the chromone will reduce the efficacy of tPA in patients. Stroke investigator developing new cytoprotective small molecules should consider adding this sensitive assay to their development and screening repertoire to assess possible drug-tPA interactions in vitro as a de-risking step.

Immunomodulation by interleukin-33 is protective in stroke through modulation of inflammation

Cerebral stroke induces massive Th1-shifted inflammation both in the brain and the periphery, contributing to the outcome of stroke. A Th1-type response is neurotoxic whereas a Th2-type response is accompanied by secretion of anti-inflammatory cytokines, such as interleukin-4 (IL-4). Interleukin-33 (IL-33) is a cytokine known to induce a shift towards the Th2-type immune response, polarize macrophages/microglia towards the M2-type, and induce production of anti-inflammatory cytokines. We found that the plasma levels of the inhibitory IL-33 receptor, sST2, are increased in human stroke and correlate with a worsened stroke outcome, suggesting an insufficient IL-33-driven Th2-type response. In mouse, peripheral administration of IL-33 reduced stroke-induced cell death and improved the sensitivity of the contralateral front paw at 5days post injury. The IL-33-treated mice had increased levels of IL-4 in the spleen and in the peri-ischemic area of the cortex. Neutralization of IL-4 by administration of an IL-4 antibody partially prevented the IL-33-mediated protection. IL-33 treatment also reduced astrocytic activation in the peri-ischemic area and increased the number of Arginase-1 immunopositive microglia/macrophages at the lesion site. In human T-cells, IL-33 treatment induced IL-4 secretion, and the conditioned media from IL-33-exposed T-cells reduced astrocytic activation. This study demonstrates that IL-33 is protective against ischemic insult by induction of IL-4 secretion and may represent a novel therapeutic approach for the treatment of stroke.

Intra-arterial thrombolysis in acute ischemic stroke: a review of pharmacologic approaches

Ischemic stroke is a major public health problem worldwide. The potential to cure stroke patients with intravenous thrombolytic therapy has evolved to the use of intra-arterial thrombolytic agents. Fewer than 200 patients have been enrolled in randomized trials of intra-arterial therapy. In this article the authors have reviewed the literature listed in MEDLINE and EMBase, and searched relevant articles to examine the role of fibrinolytic agents in acute interventional stroke therapy. Only English language articles reporting five or more patients were included. Outcomes were defined at 90 days. Good outcome was defined on the modified Rankin Scale. Symtpomatic hemorrhage was defined as hemorrhage in the setting of clinical deterioration in the first 24 to 48 h. The search identified 57 studies of which 44 reported usable data. Only three randomized trials were reported. Of a total of 1140 patients, most (73%) were treated open-label with urokinase (Abbokinase, Abbott Laboratories). The best outcomes were reported in case series and slightly worse outcomes were reported in clinical trials. Overall, it was not possible to distinguish whether one agent was superior to the others. There is a paucity of published evidence on intra-arterial therapy for acute ischemic stroke. Alteplase (Activase, Genentech Inc.) is currently the drug of choice simply because it is available and it is the current intravenous standard. Further trials and developments are anticipated.

Diagnostic imaging for acute ischemic stroke management

Although our clinical understanding remains our most important diagnostic tool, acute stroke therapy without neuroimaging is impossible. In most patients, only non-contrast computed tomography is used for diagnosis of acute stroke. However, findings based exclusively on clinical assessment and nonhemorrhagic computed tomography scans may no longer be appropriate for acute stroke treatment. From a pathophysiologic point of view, advanced computed tomography techniques and stroke magnetic resonance imaging provide much more information about the acute stroke patient as the basis of decision making in acute stroke treatment. Advanced computed tomography may provide information comparable with stroke magnetic resonance imaging, although a more detailed evaluation concerning these methods in clinical practice is required. This review gives the reader an integrated view on the current status of acute stroke imaging based on advanced computed tomography and multiparametric stroke magnetic resonance imaging protocols. These new imaging techniques allow for a far more individualized method of decision making according to the findings in each patient. This results in improved identification of patients with acute stroke syndromes, improved patient selection of those patients who are regarded suitable for thrombolysis, an extension of the rather strictly defined therapeutic time window for treatment, as well as a more sophisticated method of introduction of alternative therapies into clinical practice.

Medical therapy for ischemic stroke: review of intravenous and intra-arterial treatment options

BACKGROUND

Thrombolytic therapy is of proven and substantial benefit for select patients with acute cerebral ischemia. Diagnostic options and medical treatment options for acute stroke ischemia have undergone enormous changes in the past decades. Whereas initially stroke treatment was reduced to prevention, management of symptoms, and rehabilitation, nowadays a multitude of different fibrinolytic drugs are available. The wide availability of computed tomography in the late 1980s made thrombolysis a real therapeutic option because it allowed a fast and accurate differentiation between ischemic and hemorrhagic stroke.

METHODS

This study reviews these developments and how they have shaped our current use and understanding of thrombolytics in the treatment of acute ischemic stroke.

RESULTS

Patient selection remains a central aspect of thrombolytic treatment, and to date, the use of different fibrinolytics has been studied in over 20 large randomized trials for different clinical settings, time windows, and routes of administration. These studies included over 7000 patients, and led to our current understanding of the use of thrombolysis in acute stroke.

CONCLUSIONS

Intravenous fibrinolytic therapy within the first 3 hours of ischemic stroke onset offers substantial benefits for virtually all patients with potentially disabling deficits. In the 3- to 4.5-hour treatment window, intravenous fibrinolytic therapy has been shown to offer moderate net benefits when applied to all patients with potentially disabling deficits. Intra-arterial fibrinolytic therapy in the 3- to 6-hour window offers moderate net benefits when applied to all patients with potentially disabling deficits and large-artery cerebral thrombotic occlusions.

Perfusion CT in childhood stroke--initial observations and review of the literature

INTRODUCTION

To report the preliminary results of contrast-enhanced perfusion multi-detector CT for diagnoses of perfusion disturbances in children with clinical suspicion of stroke.

PATIENTS AND METHODS

Within the last two years emergency perfusion CT was performed in ten children (age: 8-17 years, male:female=3:7) for assessment of suspected childhood stroke. These intracranial perfusion CT, intracranial CT-digital subtraction angiography (CT-DSA) and extracranial CT-angiography (CTA) studies were retrospectively reviewed and compared with MRI, follow-up CT, catheter angiography and final clinical diagnosis. The total dose length product (DLP) for the entire examination was recorded. The image quality of perfusion CT-maps, CT-DSA and CTA were evaluated with a subjective three-point scale ranging from very good to non-diagnostic image quality rating perfusion disturbance, intracranial peripheral vessel depiction, and motion- or streak artifacts.

RESULTS

In nine of ten children perfusion CT showed no false positive or false negative results. In one of ten children suffering from migraine focal hypo-perfusion was read as perfusion impairment potentially indicating early stroke, but MRI and MRA follow-up were negative. Overall, perfusion-CT with CT-DSA was rated very good in 80% of cases for the detection of perfusion disturbances and vessel anatomy.

CONCLUSIONS

In comparison to standard CT, contrast-enhanced perfusion CT improves CTs' diagnostic capability in the emergency examination of children with a strong suspicion of ischemic cerebral infarction.

Taking a light approach to treating acute ischemic stroke patients: transcranial near-infrared laser therapy translational science

Transcranial near-infrared laser therapy (NILT) has been investigated as a novel neuroprotective treatment for acute ischemic stroke (AIS), for approximately 10 years. Two clinical trials, NeuroThera Effectiveness and Safety Trial (NEST)-1 and NEST-2, have evaluated the use of NILT to promote clinical recovery in patients with AIS. This review covers preclinical, translational, and clinical studies documented during the period 1997-2010. The primary aim of this article is to detail the development profile of NILT to treat AIS. Secondly, insight into possible mechanisms involved in light therapy will be presented. Lastly, possible new directions that should be considered to improve the efficacy profile of NILT in AIS patients will be discussed. The use of NILT was advanced to clinical trials based upon extensive translational research using multiple species. NILT, which may promote functional and behavioral recovery via a mitochondrial mechanism and by enhancing cerebral blood flow, may eventually be established as an Food and Drug Administration (FDA)-approved treatment for stroke. The NEST-3 trial, which is the pivotal trial for FDA approval, should incorporate hypotheses derived from translational studies to ensure efficacy in patients. Future NILT studies should consider administration of a thrombolytic to enhance cerebral reperfusion alongside NILT neuroprotection.

A critical assessment of edaravone acute ischemic stroke efficacy trials: is edaravone an effective neuroprotective therapy?

IMPORTANCE OF THE FIELD

Edaravone (Radicut) is a free radical scavenger marketed in Japan by Mitsubishi Tanabe Pharma Corp. to treat acute ischemic stroke (AIS) patients presenting within 24 h of the attack. Injectable edaravone ampoules (30 mg b.i.d., i.v., 14 days) were first approved on 23 May 2001. On 19 January 2010, as a new innovation, the Radicut BAG (Intravenous BAG) was approved by the Japanese Ministry of Health and Welfare. Efficacy of edaravone ranges from large significant clinical improvements to only modest improvements in clinical function measured using standard stroke scales when administered 6-72 h following an ischemic stroke. With almost 17 years of edaravone clinical experience, a few adverse events--including acute renal failure--have been noted.

WHAT THE READER WILL GAIN

This is the only article to date to critically review available clinical efficacy and toxicology data published in the literature to ascertain whether edaravone should be further pursued as a candidate for development worldwide.

AREAS COVERED IN THIS REVIEW

This review covers clinical studies carried out over the period 1993-2008.

TAKE HOME MESSAGE

Edaravone may be a useful neuroprotective agent to treat the > 15 million victims worldwide who are devastated by stroke annually. Additional clinical studies are necessary to verify the efficacy of edaravone.

Translational stroke research using a rabbit embolic stroke model: a correlative analysis hypothesis for novel therapy development

Alteplase (tissue plasminogen activator, tPA) is currently the only FDA-approved treatment that can be given to acute ischemic stroke (AIS) patients if patients present within 3 h of an ischemic stroke. After 14 years of alteplase clinical research, evidence now suggests that the therapeutic treatment window can be expanded 4.5 h, but this is not formally approved by the FDA. Even though there remains a significant risk of intracerebral hemorrhage associated with alteplase administration, there is an increased chance of favorable outcome with tPA treatment. Over the last 30 years, the use of preclinical models has assisted with the search for new effective treatments for stroke, but there has been difficulty with the translation of efficacy from animals to humans. Current research focuses on the development of new and potentially useful thrombolytics, neuroprotective agents, and devices which are also being tested for efficacy in preclinical and clinical trials. One model in particular, the rabbit small clot embolic stroke model (RSCEM) which was developed to test tPA for efficacy, remains the only preclinical model used to gain FDA approval of a therapeutic for stroke. Correlative analyses from existing preclinical translational studies and clinical trials indicate that there is a therapeutic window ratio (ARR) of 2.43-3 between the RSCEM and AIS patients. In conclusion, the RSCEM can be used as an effective translational tool to gauge the clinical potential of new treatments.

The development of stroke therapeutics: promising mechanisms and translational challenges

Ischemic stroke is the second most common cause of death worldwide and a major cause of disability. Intravenous thrombolysis with rt-PA remains the only available acute therapy in patients who present within 3h of stroke onset other than the recently approved mechanical MERCI device, substantiating the high unmet need in available stroke therapeutics. The development of successful therapeutic strategies remains challenging, as evidenced by the continued failures of new therapies in clinical trials. However, significant lessons have been learned and this knowledge is currently being incorporated into improved pre-clinical and clinical design. Furthermore, advancements in imaging technologies and continued progress in understanding biological pathways have established a prolonged presence of salvageable penumbral brain tissue and have begun to elucidate the natural repair response initiated by ischemic insult. We review important past and current approaches to drug development with an emphasis on implementing principles of translational research to achieve a rigorous conversion of knowledge from bench to bedside. We highlight current strategies to protect and repair brain tissue with the promise to provide longer therapeutic windows, preservation of multiple tissue compartments and improved clinical success.

Brain perfusion CT: principles, technique and clinical applications

The imaging of brain haemodynamics and its applications are generating growing interest. By providing quantitative measurements of cerebral blood flow (CBF) and cerebral blood volume (CBV), dynamic perfusion computed tomography (p-CT) allows visualisation of cerebral autoregulation mechanisms and represents a fast, available and reliable imaging option for assessing cerebral perfusion. Thanks to its feasibility in emergency settings, p-CT is considered most useful, in combination with CT angiography, in acute ischaemic patients, as it is able to provide a fast and noninvasive assessment of cerebral perfusion impairment. In addition, p-CT can play a diagnostic role in other types of cerebrovascular disease to assess functional reserve, and in intracranial neoplasms, where it has a role in diagnosis, grading, biopsy guidance, and follow-up during treatment. This article illustrates the principles, technique and clinical applications of p-CT cerebral perfusion studies.

[Thrombolysis for ischemic stroke: an update]

Even 10 years after the approval of thrombolysis this life-saving and disability reducing therapy is still underused. Important reasons for that are very strict inclusion criteria such as the early and narrow time-window, fear of bleeding complications and doubts regarding the effectiveness. An intensive and constant effort is required to educate the public that stroke is a treatable emergency. In addition to the medical reasons, economic considerations in a context of decreasing resources emphasize the importance of effective stroke treatment. The results of numerous recent studies such as the European register SITS-MOST help to strengthen the confidence in thrombolysis. In addition the development and advancement of new imaging tools such as multiparametric MRI and advanced CT-techniques will improve patient selection and may enable us to extend the time-window for treatment. Intraarterial thrombolysis, "bridging" methods and new devices for intravascular intervention are the subjects of intensive ongoing research. Even though no randomized trials are available intraarterial thrombolysis is the treatment of choice for acute basilar occlusion, but if this intervention is not available an intravenous approach may be an equal alternative.

Advances in ischemic stroke treatment: neuroprotective and combination therapies

Thrombolysis with intravenous alteplase (recombinant tissue-type plasminogen activator) continues to be the sole recourse for acute ischemic stroke therapy, provided that patients seek treatment preferably within 3 h of stroke onset. The narrow window of efficacy, coupled with the significant risk of hemorrhage and the high mortality rate, preclude the use of alteplase beyond this time frame. Moreover, in part because of safety concerns, only a small percentage (6-15%) of eligible patients is treated with alteplase. Clearly, safer and more effective treatments that focus on improving the shortcomings of the present thrombolysis for stroke need to be identified. Therefore, newer thrombolytics are being developed with the goal of minimizing side effects, while also shortening the time of cerebral reperfusion and extending the therapeutic window of efficacy. Besides thrombolytics, new and potentially useful drugs and devices are also being studied either as monotherapeutic agents or for use in conjunction with alteplase. In animal models of stroke, neuroprotective agents that affect various components of the ischemic injury cascade that results in neurodegeneration have shown promise for the latter. Examples of such agents include spin traps that block oxidative stress, metalloprotease inhibitors that prevent vascular damage, anti-inflammatory drugs that suppress inflammation and transcranial infrared laser irradiation, which promotes recovery of function. Ideally, a successful combination of neuroprotectant (drug or device) and thrombolytic therapy for stroke would minimize the side effects of thrombolysis followed by supplementary neuroprotection thereafter.

Therapy for early reperfusion after stroke

Ischemic stroke is a leading cause of death and disability in the Western world. At present, intravenous administration of tissue plasminogen activator within 3 h of symptom onset is the only proven effective treatment to re-establish cerebral blood flow in the case of acute vessel occlusion. Unfortunately, few patients presenting with acute ischemic stroke qualify for intravenous tissue plasminogen activator therapy. The focus of current research is, therefore, to find new treatment options by which to obtain early reperfusion, and to extend the therapeutic window for intervention beyond 3 h. The purpose of this Review is to provide an integrated view of the current state of reperfusion therapy in patients with acute stroke, including pharmacologic agents and the methods of delivery. The focus will be on intravenous and intra-arterial use of plasminogen activators in acute supratentorial infarction. Other therapies, such as antiplatelet agents (i.e. glycoprotein IIb/IIIa inhibitors), and anticoagulant drugs will be discussed briefly.

Thrombolytic therapy for acute ischemic stroke: 3 h and beyond

The current status of thrombolytic therapy approved by the US Food and Drug Administration is intravenous recombinant plasminogen activator given within 3 h of the onset of ischemic stroke. Intra-arterial therapy is possible for up to 6 h but is not Food and Drug Administration-approved for this purpose. Based on current radiologic methods (i.e., magnetic resonance imaging and perfusion computed tomography scans), it is being increasingly realized that the time window for effective thrombolytic therapy is variable, and salvageable tissue in the form of the ischemic penumbra may exist for longer periods of time and could therefore offer a greater time window based on these imaging studies. Development of an effective neuroprotective drug would greatly enhance the stability of the penumbra and offer further opportunities for extending the time window for reperfusion.

Effects of Intra-arterial Urokinase on a Non-human Primate Thromboembolic Stroke Model

One of the most important prognostic factors in the thrombolytic treatment of acute ischemic stroke is to re-canalize. The purpose of this study was to evaluate the effectiveness and safety of urokinase in a primate thromboembolic stroke model. Thromboembolic stroke was accomplished via occlusion of the middle cerebral artery (MCA) obtained by injecting an autologous blood clot into the left internal carotid artery in 21 male cynomolgus monkeys. Animals were randomly assigned to the following treatment groups: Group 1: vehicle (saline), Group 2: urokinase (40,000 IU), Group 3: urokinase (120,000 IU,) over 2 or 6 h via intra-internal carotid catheter starting 1 h after embolization, respectively. In the urokinase-treated groups, neurologic deficits were improved in consciousness and skeletal muscle coordination, but not sensory and motor systems. The infarction size in Group 2 (11.9 +/- 3.9% of the hemisphere) and 3 (7.6 +/- 2.5%) were significantly smaller than that (24.7 +/- 3.5%) in Group 1. However, 2 of 5 animals in Group 3 died. In conclusion, urokinase improved neurologic deficits and reduced cerebral infarction on thromboembolic stroke in the cynomolgus monkey.

Recent Advances in the Interventional Treatment of Acute Ischemic Stroke

BACKGROUND

Acute ischemic stroke is a major cause of morbidity and mortality in Europe, North America, and Asia. Recent advances over the past decade have been made in the interventional approach to patients with a stroke. These include intravenous (i.v.) trials, intra-arterial (i.a.) trials, combined i.v./i.a. trials, and newer devices undergoing current clinical evaluation to mechanically remove clot within the cerebral circulation.

METHODS

A summary of the latest interventional approaches to stroke, from the interventional neuroradiology perspective, is presented. Results of the major thrombolytic trials over the past decade are summarized. Newer devices and approaches for ischemic stroke patients, including the recently completed Phase 1/2 MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial are presented.

RESULTS

The Proact 1 and 2 trials involving i.a. thrombolytic therapy in patients who present with an acute middle cerebral artery stroke within 6 h from symptom onset have demonstrated significant benefit over the control group, for improved outcomes at 90 days. The MERCI trial has demonstrated, in 114 patients with moderate to severe strokes, that patients who are able to be recanalized have significant neurological improvement versus those who were not able to be recanalized.

CONCLUSIONS

Continued advances in the interventional approach to acute stroke treatment, with further clinical trials, are warranted. Early reports are encouraging regarding both combination thrombolytic drug trials and mechanical device trials for these patients.

Lower Incidence of Symptomatic Vasospasm after Subarachnoid Hemorrhage owing to Ruptured Vertebrobasilar Aneurysms

OBJECTIVE:

In this study, we evaluated the difference in incidence of symptomatic vasospasm between ruptured aneurysms in the anterior and posterior circulation using multiple logistic regression analysis.

METHODS:

A total of 145 consecutive patients who underwent surgery for aneurysms within 72 hours after subarachnoid hemorrhage (SAH) were studied.

RESULTS:

The ruptured aneurysm was in the anterior circulation in 128 patients (88.3%) and in the posterior circulation in 17 patients (11.7%). Forty patients (27.6%) had symptomatic vasospasm and 105 patients (72.4%) did not. Univariate and multivariate analyses were performed to assess relationships among various variables and the occurrence of symptomatic vasospasm after SAH. Finally, Grade III to V (Hunt and Hess grade) and Group 3 (Fisher's classification) on admission were found to be independently positively associated with the occurrence of symptomatic vasospasm while ruptured vertebrobasilar aneurysm were negatively associated.

CONCLUSION:

Although a poor clinical grade and a severe SAH classification on admission such as Hunt and Hess grade and Fisher's classification are established powerful predictors of symptomatic vasospasm, ruptured vertebrobasilar aneurysm are for the first time reported to be a predictor of symptomatic vasospasm based on results of a recent reliable statistical analysis.

Intra-arterial thrombolysis in acute ischaemic stroke

Several thrombolytic agents for the treatment of acute ischaemic stroke have been examined; however, to date, only the i.v. administration of recombinant tissue plasminogen activator is licensed in Australia. Although no trials directly comparing intra-arterial and i.v. delivery of thrombolytics exist, intra-arterial thrombolysis has several potential advantages, including angiographic assessment of the thrombus and the site of occlusion and collateral circulation, improved recanalization, and delivery of higher local concentrations of thrombolytic agents and extending the therapeutic time window for treatment. We conducted a retrospective audit of our experience with the use of intra-arterial urokinase to treat acute ischaemic stroke at an Australian tertiary-care hospital between June 1993 and June 2003. We examined time from stroke onset to assessment, computerized tomography scan, cerebral angiography and thrombolysis, anatomical classification of intra-arterial thrombus, rates of symptomatic intracerebral haemorrhage, and clinical outcome at 3 months. We believe that in carefully selected individuals in appropriate centres of expertise, intra-arterial thrombolytic therapy holds great promise.

Recommendations for Comprehensive Stroke Centers

Background and Purpose— To develop recommendations for the establishment of comprehensive stroke centers capable of delivering the full spectrum of care to seriously ill patients with stroke and cerebrovascular disease. Recommendations were developed by members of the Brain Attack Coalition (BAC), which is a multidisciplinary group of members from major professional organizations involved with the care of patients with stroke and cerebrovascular disease.

Summary of Review— A comprehensive literature search was conducted from 1966 through December 2004 using Medline and Pub Med. Articles with information about clinical trials, meta-analyses, care guidelines, scientific guidelines, and other relevant clinical and research reports were examined and graded using established evidence-based medicine approaches for therapeutic and diagnostic modalities. Evidence was also obtained from a questionnaire survey sent to leaders in cerebrovascular disease. Members of BAC reviewed literature related to their field and graded the scientific evidence on the various diagnostic and treatment modalities for stroke. Input was obtained from the organizations represented by BAC. BAC met on several occasions to review each specific recommendation and reach a consensus about its importance in light of other medical, logistical, and financial factors.

Conclusions— There are a number of key areas supported by evidence-based medicine that are important for a comprehensive stroke center and its ability to deliver the wide variety of specialized care needed by patients with serious cerebrovascular disease. These areas include: (1) health care personnel with specific expertise in a number of disciplines, including neurosurgery and vascular neurology; (2) advanced neuroimaging capabilities such as MRI and various types of cerebral angiography; (3) surgical and endovascular techniques, including clipping and coiling of intracranial aneurysms, carotid endarterectomy, and intra-arterial thrombolytic therapy; and (4) other specific infrastructure and programmatic elements such as an intensive care unit and a stroke registry. Integration of these elements into a coordinated hospital-based program or system is likely to improve outcomes of patients with strokes and complex cerebrovascular disease who require the services of a comprehensive stroke center.

[Acute cerebral circulation problems]

Acute stroke is the third most common cause of death and also the most common cause of permanent disability in industrialized countries. Ischemic stroke is caused by occlusion of a cerebral artery leading to a critical reduction in brain perfusion in the respective brain area (penumbra). Most acute stroke treatment strategies are based on the penumbra concept: attaining rapid and persistent reperfusion is followed by the protection of critically ischemic and not yet infarcted (penumbral) tissue by, e.g., neuroprotection. Examination of the acute stroke patient includes a brief history, neurostatus and imaging (CT or MRI) for the exclusion of intracerebral hemorrhage. The diagnostic standard is CT; modern stroke MRI protocols provide an improved selection in later time windows. Intravenous thrombolysis with rt-PA within 3 h of symptom onset is the only approved therapy with a proven significant benefit for the patient. The effect is smaller but still significant if treatment occurs up to 4.5 h, and may still be present in MRI selected patients up to 9 h. More aggressive forms of therapy include interventional reperfusion techniques and therapy of malignant MCA infarction such as hemicraniectomy and hypothermia, which at present, however, are not routine and are only performed in specialized centers.

Intraarterielle Lyse der A. cerebri media: ein Überblick

Until 1996, treatment of strokes consisted exclusively of efforts to prevent recurrence. The development of intravenous and intra-arterial thrombolysis changed the approach to a causal therapy. This article provides an overview of state-of-the-art intravenous and intra-arterial therapeutic concepts and attempts to define the position of the local intra-arterial fibrinolysis approach.

Treatments for stroke

Stroke is the third leading cause of death and the leading cause of disability in developed countries, yet remains a poorly treated condition. Treatments for stroke can be aimed at acutely improving blood flow or protecting brain tissue against ischaemia, enhancing stroke recovery or reducing the risk of stroke recurrence. This paper reviews each of these approaches, particularly focusing on mechanisms for which there are agents in clinical trials. There are a number of appealing neuroprotective agents in Phase II and III clinical trials. However, the majority of acute treatments are likely to suffer from a narrow therapeutic time window and hence limited patient access. Combinations of acute approaches are likely to offer the greatest benefit, but present challenges in development. Promotion of recovery following stroke offers enormous potential for successful therapeutic intervention. Excitingly, new developments in preclinical research have identified possible ways in which this may be achieved.

Fast patient workup in acute stroke using parallel imaging

Treatment of ischemic stroke is a very frustrating topic for neurologists. Presently, the most promising therapy seems to be thrombolysis of the clot. However, this intervention is associated with complication risks, most significantly the risk of post-treatment hemorrhage. This risk of bleeding increases not only with the size of the ischemic brain tissue but also with the time-to-treatment interval. Studies suggest a time window of 3 hours for most effective treatment. Hence, there is demand for a rapid imaging workup, which thus far has been accomplished with computed tomography. Because of the risks associated with thrombolytic therapy, more detailed information is desirable. The distinction between patients with viable ischemically challenged neural tissue and those with complete infarcts is of great importance, and computed tomography is insufficient for this task. This is also true for outlining the etiology of stroke, which may impact treatment. For these tasks, magnetic resonance imaging has been proposed. However, comprehensive imaging protocols take time, which is limited in stroke treatment. Therefore, new imaging techniques are required that provide both in-depth information and short scanning times. Parallel imaging is uniquely suited for this purpose.

Antithrombotic and Thrombolytic Therapy for Ischemic Stroke

This chapter about treatment and prevention of stroke is part of the 7th ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al). Among the key recommendations in this chapter are the following: For patients with acute ischemic stroke (AIS), we recommend administration of i.v. tissue plasminogen activator (tPA), if treatment is initiated within 3 h of clearly defined symptom onset (Grade 1A). For patients with extensive and clearly identifiable hypodensity on CT, we recommend against thrombolytic therapy (Grade 1B). For unselected patients with AIS of > 3 h but < 6 h, we suggest clinicians not use i.v. tPA (Grade 2A). For patients with AIS, we recommend against streptokinase (Grade 1A) and suggest clinicians not use full-dose anticoagulation with i.v. or subcutaneous heparins or heparinoids (Grade 2B). For patients with AIS who are not receiving thrombolysis, we recommend early aspirin therapy, 160 to 325 mg qd (Grade 1A). For AIS patients with restricted mobility, we recommend prophylactic low-dose subcutaneous heparin or low molecular weight heparins or heparinoids (Grade 1A); and for patients who have contraindications to anticoagulants, we recommend use of intermittent pneumatic compression devices or elastic stockings (Grade 1C). In patients with acute intracerebral hematoma, we recommend the initial use of intermittent pneumatic compression (Grade 1C+). In patients with noncardioembolic stroke or transient ischemic attack (TIA) [ie, atherothrombotic, lacunar or cryptogenic], we recommend treatment with an antiplatelet agent (Grade 1A) including aspirin, 50 to 325 mg qd; the combination of aspirin and extended-release dipyridamole, 25 mg/200 mg bid; or clopidogrel, 75 mg qd. In these patients, we suggest use of the combination of aspirin and extended-release dipyridamole, 25/200 mg bid, over aspirin (Grade 2A) and clopidogrel over aspirin (Grade 2B). For patients who are allergic to aspirin, we recommend clopidogrel (Grade 1C+). In patients with atrial fibrillation and a recent stroke or TIA, we recommend long-term oral anticoagulation (target international normalized ratio, 2.5; range, 2.0 to 3.0) [Grade 1A]. In patients with venous sinus thrombosis, we recommend unfractionated heparin (Grade 1B) or low molecular weight heparin (Grade 1B) over no anticoagulant therapy during the acute phase.

Therapeutic time window of thrombolytic therapy following stroke

Stroke is the third leading cause of death after myocardial infarction and cancer and the leading cause of permanent disability and of disability-adjusted loss of independent life-years in Western countries. Thrombolysis is the treatment of choice for acute stroke within 3 hours after symptom onset. Treatment beyond the 3-hour time window has not been shown to be effective in any single trial; however, meta-analyses suggest a somewhat less but still significant effect within 3 to 6 hours after stroke. It seems reasonable to apply improved selection criteria that would allow one to differentiate patients with a relevant indication for thrombolytic therapy from those who do not have one. We present an overview of a diagnostic approach to acute stroke management that allows the clinician to individualize patient management based on pathophysiologic reasoning and not rigid time windows established by randomized controlled trials. Therefore, this review concentrates on giving the reader an integrated knowledge of the current status of thrombolytic therapy in stroke and then develops a treatment algorithm based on pathophysiologic information rendered by a multiparametric stroke magnetic resonance imaging protocol.

An update on thrombolytic therapy for acute stroke

PURPOSE OF REVIEW

Stroke is the third leading cause of death after myocardial infarction and cancer, and is the leading cause of permanent disability and disability-adjusted loss of independent life-years in western countries. Thrombolysis is the treatment of choice for acute stroke within 3 h after the onset of symptoms. We present an overview of a diagnostic approach to acute stroke management that allows the individualization of patient management based on pathophysiological reasoning and not rigid time windows established by randomized controlled trials.

RECENT FINDINGS

This review concentrates in the first part on giving the reader an integrated knowledge of the current status of thrombolytic therapy in stroke, and in the second part develops a treatment algorithm based on pathophysiological information rendered by a multiparametric stroke magnetic resonance imaging protocol.

SUMMARY

Thrombolysis is an effective therapy for ischemic stroke, whether performed intravenously within 3 h or intra-arterially within 3-6 h. Meta-analyses have provided evidence of an effect of intravenous thrombolysis beyond the 3 h time window, especially when improved selection criteria such as modern magnetic resonance imaging protocols are applied. Sadly, thrombolysis is still underused. Positive results from studies currently underway may encourage more centers to offer this therapy to an increasing number of stroke patients, and thereby reduce the considerable socioeconomic burden of stroke.

Intraarterial Thrombolysis Trials in Acute Ischemic Stroke

Stroke is a common cause of death and disability in industrialized nations. Technical advances and the increased availability of noninvasive brain imaging techniques have permitted precise and early diagnosis of acute cerebral ischemia. This has made emergent thrombolytic therapy for rapid restoration of cerebral perfusion increasingly possible. Herein, the authors present a review of the clinical trials investigating acute stroke treatment with intraarterial thrombolysis.

Pharmacological treatment of acute ischemic stroke

Ischemic stroke is devastating. It is the third leading cause of death in the United States. Each year, 480,000 people fall victim to ischemic stroke, which is estimated to cost 71.8 billion dollars (Hinkle JL, Bowman L. J Neurol Nurs. 2003;35:1-8. New treatment is available. Acute ischemic stroke is no longer considered an accident resulting in damage that must simply be dealt with. Now termed a brain attack, like a heart attack it must be treated immediately. Education is key to improving outcomes. Health care professionals must be trained to recognize early signs and symptoms of stroke. The public must be educated to understand the urgency of early evaluation once symptoms of stroke occur Brown M. Clin Med. 2001; 1:60-65). Television commercials, billboards, and public health lectures can be advantageous in a campaign to educate about stroke and the need to seek help immediately when experiencing symptoms, to halt the ischemic damage Brown M. Clin Med. 2001; 1:60-65.

Inhibition of intercellular adhesion molecule-1 protein expression by antisense oligonucleotides is neuroprotective after transient middle cerebral artery occlusion in rat

BACKGROUND AND PURPOSE

The present study was performed to determine whether antisense inhibition of intercellular adhesion molecule-1 (ICAM-1) protein expression decreases focal ischemic brain damage.

METHODS

Male spontaneously hypertensive rats underwent 1-hour middle cerebral artery occlusion (MCAO) and 24-hour reperfusion. Rats were infused with ICAM-1 antisense or control oligodeoxynucleotides (ODNs) (48 nmol/d ICV) or vehicle, starting 24 hours before MCAO and continuing until the time of death. ICAM-1 and vascular cell adhesion molecule-1 (VCAM-1) mRNA levels were measured by real-time polymerase chain reaction. ICAM-1 protein knockdown was confirmed by Western blotting. Infarct volume was quantified by the use of cresyl violet-stained brain sections. Neurological deficits were evaluated. Mean arterial blood pressure was recorded by laser Doppler. Tissue penetration of antisense was confirmed by the use of fluorescent ODNs.

RESULTS

Transient MCAO upregulated ICAM-1, but not VCAM-1, mRNA expression in the ipsilateral cortex between 3 and 72 hours of reperfusion. ICAM-1 antisense infusion prevented ischemia-induced ICAM-1 protein expression and reduced total infarct volume (by 53%; P<0.05; 226+/-35 mm3 in control ODN group and 104+/-27 mm3 in antisense ODN group; n=8 each) and mean neurological deficit score (by 44%; P<0.05; 2.4 in control ODN group and 1.3 in antisense ODN group; n=8 each). Neither control nor antisense ODN had any effect on mean arterial blood pressure and the physiological parameters monitored during MCAO. Compared with noninfused control, intracerebroventricular infusion of artificial cerebrospinal fluid or antisense or sense ODN had no significant effect on the regional cerebral blood flow changes that accompanied ischemia and reperfusion.

CONCLUSIONS

Increased ICAM-1 expression is implicated in the pathogenesis of focal ischemia since ICAM-1 protein knockdown decreased ischemic brain damage. The mechanism by which ICAM-1 inhibition offers neuroprotection is independent of blood pressure modulation.

MRI-guided therapy in acute stroke

Stroke is the third leading cause of death after myocardial infarction and cancer and the leading cause of permanent disability and of disability-adjusted loss of independent life-years in Western countries. Thrombolysis is the treatment of choice for acute stroke within 3 h after onset of symptoms. Treatment beyond the 3-h time window has not been shown to be effective in any single trial, however, meta-analyses suggest a somewhat less but still significant effect within 3 to 6 h after stroke. It seems reasonable to apply improved selection criteria that allow the differentiation of patients with a relevant indication for thrombolytic therapy from those who have not. An overview of a diagnostic approach to acute stroke management that allows patient management individualization based on pathophysiological reasoning and not rigid time windows, established by randomized controlled trials is presented. Therefore, this review concentrates in the first part on giving the reader an integrated knowledge of the current status of thrombolytic therapy in stroke, and in the second part, develops a treatment algorithm based on pathophysiological information rendered by a multiparametric stroke magnetic resonance imaging protocol.

Imaging-Based Decision Making in Thrombolytic Therapy for Ischemic Stroke

Background— Thrombolysis is the treatment of choice for acute stroke within 3 hours after symptom onset. Treatment beyond the 3-hour time window has not been shown to be effective in any single trial; however, meta-analyses suggest a somewhat lesser but still significant effect within 3 to 6 hours after stroke. It seems reasonable to apply improved selection criteria that allow differentiation between patients with and without a relevant indication for thrombolytic therapy.

Summary of Review— The present literature on imaging in stroke has been thoroughly reviewed, covering Doppler ultrasound (DU), arteriography, CT, and MRI and including modern techniques such as perfusion CT, diffusion- and perfusion-weighted MRI (DWI, PWI), CT angiography and MR angiography (CTA, MRA), and CTA source image analysis (CTA-SI). The authors present their view of a comprehensive diagnostic approach to acute stroke, which challenges the concept of a rigid therapeutic time window.

Conclusions— Information about the presence or absence of a vessel occlusion, whether by means of DU, CTA, or MRA, is essential before recombinant tissue plasminogen activator is given in the 3- to 6-hour time window. Clear demarcation of the irreversibly damaged infarct core and the ischemic but still viable and thus salvageable tissue at risk of infarction as seen on DWI/PWI/MRA or alternatively CT/CTA/CTA-SI should be obtained before thrombolysis is initiated within 3 to 6 hours. Once these advanced techniques are used, the therapeutic time window can be extended with acceptable safety. However, comprehensive informed consent is mandatory, especially when thrombolytic therapy is considered beyond established time windows.