Thrombolytic therapy for ischemic stroke--a review. Part I--Intravenous thrombolysis

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.

Efficacy of urokinase and alteplase intravenous thrombolysis in the treatment of acute phase cerebral infarction and impact on serum S-100β and nerve growth factor levels

OBJECTIVE

To compare the efficacy of urokinase and alteplase intravenous thrombolysis in the treatment of acute phase cerebral infarction and investigate their impact on serum S-100β and nerve growth factor (NGF) levels.

METHODS

Parameters assessed included NIHSS score reduction, vascular recanalization rates, mRS, Barthel Index, and adverse reactions. Post-treatment blood samples were also collected for further analysis.

RESULTS

The clinical treatment effectiveness and Vascular recanalization rate in Group A was higher than in Group B, with p < 0.05. After treatment, the NIHSS score in Group A was lower than in Group B (p < 0.05), and the mRS score was slightly lower, but the difference was not significant (p > 0.05). After treatment, the levels of IL-6, TNF-α, and CRP in Group A were lower than in the control group (p < 0.05). The S-100β level in Group A was lower than in Group B, and NGF level was higher than in Group B (p < 0.05). Group A had better prognosis.

CONCLUSION

The efficacy and safety of both urokinase and alteplase intravenous thrombolysis for acute phase cerebral infarction have been demonstrated, yet disparities exist in neurological function recovery and regulation of biochemical indicators. Alteplase intravenous thrombolysis emerges as the superior option, displaying greater effectiveness and safety, alongside improved regulation of serum S-100β and NGF levels. Tailoring treatment plans to individual patient characteristics and drug mechanisms is essential. Given these findings, the promotion of alteplase intravenous thrombolysis in the management of acute phase cerebral infarction is justified.

Puerariae Lobatae Radix with chuanxiong Rhizoma for treatment of cerebral ischemic stroke by remodeling gut microbiota to regulate the brain-gut barriers

The combination of Puerariae Lobatae Radix (PLR) and Chuanxiong Rhizoma (CXR) is commonly used to treat cerebrovascular diseases. This work aimed to clarify the mechanisms of their action in treating cerebral ischemic stroke from the perspective of gut microecology. The PLR and CXR combination effectively improved the neurological function, reduced the cerebral infarction and relieved the complications of cerebral ischemic stroke, including dyslipidemia, increased blood viscosity and thrombotic risk. Cerebral ischemic stroke triggered gut microbial disturbances by enriching pathogens and opportunistic microorganisms, including Bacteroides, Escherichia_Shigella, Haemophilus, Eubacterium_nodatum_group, Collinsella, Enterococcus, Proteus, Alistipes, Klebsiella, Shuttleworthia and Faecalibacterium. Cerebral ischemic stroke also increased the intestinal permeability, disrupted the gut barrier and caused intestinal microbial translocation. Occludin, claudin-5 and ZO-1 levels in the brain-gut barriers showed a high positive correlation. However, the combination remodeled the gut microecology by modulating endogenous bacteria whose effects may mitigate cerebral damage, such as Alloprevotella, Ruminococcaceae, Oscillospira, Lachnospiraceae_NK4B4_group, Akkermansia and Megasphaera, protected the brain-gut barriers by increasing claudin-5 and ZO-1 levels; and weakened the gut microbiota translocation by decreasing diamine oxidase, lipopolysaccharide and d-lactate. Although nimodipine effectively reduced the cerebral infarction, it did not relieve the gut microbiota dysbiosis and instead aggravated the gut barrier disruption and microbiota translocation. In conclusion, cerebral ischemic stroke caused gut microbiota dysbiosis, increased intestinal permeability, disrupted the gut barrier and triggered gut microbiota translocation. The PLR and CXR combination was an effective treatment for cerebral ischemic stroke that relieved the gut microbiota dysbiosis and brain-gut barriers disruption.

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).

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.

Therapeutic effect of recombinant tissue plasminogen activator on acute cerebral infarction at different times

BACKGROUND

The study aimed to compare the therapeutic effect of recombinant tissue plasminogen activator (rt-PA) on the onset of acute cerebral infarction (ACI) at different time points of the first 6 hours.

METHODS

A retrospective analysis was conducted in 74 patients who received rt-PA thrombolysis treatment within 4.5 hours after ACI and another 15 patients who received rt-PA thrombolysis treatment between 4.5-6 hours after ACI.

RESULTS

National Institute of Health Stroke Scale (NIHSS) scores were statistically decreased in both groups (P>0.05) at 24 hours and 7 days after ACI. There was no significant difference in modified ranking scores and mortality at 90 days after the treatment between the two groups (P>0.05).

CONCLUSIONS

The therapeutic effect and mortality of rt-PA treatment in patients with ACI between 4.5-6 hours after the onset of the disease were similar to those in patients who received rt-PA within 4.5 hours after the onset of this disease. Therefore, intravenous thrombolytic therapy for ACI within 4.5-6 hours after ACI was effective and safe.

Alteplase for acute ischemic stroke

Alteplase, an intravenously administered form of recombinant tissue plasminogen activator (rt-PA), remains the only US FDA-approved thrombolytic treatment for acute ischemic stroke within 3 h of symptom onset. Patients treated with intravenous rt-PA are at least 30% more likely to have minimal or no disability at 3 months compared with placebo. Despite an increased risk of symptomatic intracranial hemorrhage, rt-PA does not increase mortality. The benefit achieved with rt-PA is cost effective and sustained 1 year after treatment. Despite its clear benefit, rt-PA remains underutilized. Although the future of acute ischemic stroke treatment will most likely involve a multi-faceted treatment approach, the primary objective remains to establish recanalization of the involved vessel. For patients with acute ischemic stroke within the first 3 h of symptom onset, rt-PA remains the first step in accomplishing this goal.

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.

Neuroglobin over expressing mice: expression pattern and effect on brain ischemic infarct size

BACKGROUND

Stroke is a major cause of death and severe disability, but effective treatments are limited. Neuroglobin, a neuronal heme-globin, has been advocated as a novel pharmacological target in combating stroke and neurodegenerative disorders based on cytoprotective properties. Using thoroughly validated antibodies and oligos, we give a detailed brain anatomical characterization of transgenic mice over expressing Neuroglobin. Moreover, using permanent middle artery occlusion the effect of elevated levels of Neuroglobin on ischemic damage was studied. Lastly, the impact of mouse strain genetic background on ischemic damage was investigated.

PRINCIPAL FINDINGS

A four to five fold increase in Neuroglobin mRNA and protein expression was seen in the brain of transgenic mice. A β-actin promoter was used to drive Neuroglobin over expression, but immunohistochemistry and in situ hybridization showed over expression to be confined to primarily the cortex, hippocampus, cerebellum, and only in neurons. The level and expression pattern of endogenous Neuroglobin was unaffected by insertion of the over expressing Ngb transgene. Neuroglobin over expression resulted in a significant reduction in infarct volume 24 hours after ischemia. Immunohistochemistry showed no selective sparing of Neuroglobin expressing cells in the ischemic core or penumbra. A significant difference in infarct volume was found between mice of the same strain, but from different colonies.

SIGNIFICANCE

In contrast to some previous reports, Neuroglobin over expression is not global but confined to a few well-defined brain regions, and only in neurons. This study confirms previous reports showing a correlation between reduced infarct volume and elevated Neuroglobin levels, but underlines the need to study the likely contribution from compensatory mechanisms to the phenotype following a genetic perturbation. We also stress, that care should be taken when comparing results where different mouse strains and colonies have been used due to large genetic background contribution to the observed phenotype.

Perioperative management of coagulation in nontraumatic intracerebral hemorrhage

This commentary seeks to clarify the recommendations and highlight the debate regarding the perioperative management of hemostasis in intracerebral hemorrhage.

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.

Whole-brain dynamic CT angiography and perfusion imaging

The availability of whole brain computed tomography (CT) perfusion has expanded the opportunities for analysing the haemodynamic parameters associated with varied neurological conditions. Examples demonstrating the clinical utility of whole-brain CT perfusion imaging in selected acute and chronic ischaemic arterial neurovascular conditions are presented. Whole-brain CT perfusion enables the detection and focused haemodynamic analyses of acute and chronic arterial conditions in the central nervous system without the limitation of partial anatomical coverage of the brain.

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.

Utility of CT perfusion with 64-row multi-detector CT for acute ischemic brain stroke

We investigated the utility of computed tomographic (CT) perfusion (CTP) with 64-row multi-detector row CT (MDCT) to diagnose acute infarction and ischemic penumbra. We reviewed 58 clinical cases with acute ischemic stroke with CTP, compared the size of the area with long mean transit time (MTT) to that with abnormal intensity in magnetic resonance (MR) diffusion-weighted imaging (DWI) to diagnose penumbra, and compared the size of the area with reduced cerebral blood volume (CBV) in CTP to that in MR DWI to evaluate sensitivity for infarction. The total sensitivity of MTT to acute ischemic lesions was 81% (47/58). Sensitivity of MTT to segmental lesions was 100% (42/42) and for spot and focal lesions, 31% (5/16). In 13 patients, penumbra was diagnosed as lesions mismatched between MTT in CTP and MR DWI. When we regarded a lesion with decreased CBV as infarction, the sensitivity of CBV to segmental lesions was 85% (11/13), and the sensitivity to small infarction was 14% (4/28). Use of 64-row MDCT improves coverage and radiation exposure in head CTP. The combination of plain CT, CT angiography, and CTP with MDCT can demonstrate all segmental ischemic lesions and most large segmental infarctions, and their combined application is useful in considering indication and contraindication for thrombolysis. The problem of low sensitivity for small lesions remains, and MR DWI may be required to assess small infarctions when findings from combined plain CT, CT angiography, and CTP are negative in patients with suspected acute brain stroke.

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.

The endovascular management of intracranial vascular disease including the MERCI device

The prompt and aggressive management of acute stroke has become the standard of care as public awareness and the available successful treatment options both increase. The intravenous administration of tissue plasminogen activator within an established treatment window has been determined through large well-designed studies. The endovascular strategies for acute stroke have evolved significantly over the past 5 years and have been prompted by the limits of the intravenous treatment, as well as by the desire to demonstrate improved recanalization rates and improved long-term outcomes. Among these interventional treatment options are the intra-arterial administration of tissue plasminogen activator and newer antiplatelet agents, mechanical thrombectomy with the MERCI device, and intracranial angioplasty and stenting. This article outlines the major studies that have defined the current field of acute stroke management and discusses the basic treatment paradigms that are commonly used today.

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.

Endovascular management of acute ischemic stroke

The management of stroke has progressed significantly over the past 2 decades due to successful treatment protocols including intravenous and intraarterial options. The intravenous administration of tissue plasminogen activator within an established treatment window has been proven in large, well-designed studies. The evolution of endovascular strategies for acute stroke has been prompted by the limits of the intravenous treatment, as well as by the desire to demonstrate improved recanalization rates and improved long-term outcomes. The interventional treatment options available today are the intraarterial administration of tissue plasminogen activator and newer antiplatelet agents, mechanical thrombectomy with the MERCI device and the Penumbra system, and intracranial angioplasty and stent placement. In this review the authors outline the major studies that have defined the current field of acute stroke management and discuss the basic treatment paradigms that are commonly used today.

Vertebrobasilar recanalization after 12 h of onset using balloon expandable stent and thrombolysis

Basilar artery (BA) thrombosis is a severe condition that has a high percentage of mortality if no treatment is performed. Recanalization is the most successful way of reducing mortality and improving outcome in patients with BA thrombosis. We present a case of a patient that presented to our hospital 12 h after onset of symptoms in which a combination of techniques were used to perform a vertebrobasilar recanalization.

Delayed matrix metalloproteinase inhibition reduces intracerebral hemorrhage after embolic stroke in rats

Hemorrhagic transformation (HT) and brain edema are life-threatening complications of recombinant tissue plasminogen activator (rt-PA)-induced reperfusion after ischemic stroke. The risk of HT limits the therapeutic window for reperfusion to 3 h after stroke onset. Pre-treatment with matrix metalloproteinase (MMP) inhibitors reduces HT and cerebral edema in experimental stroke. However, whether a delayed therapeutic intervention would be beneficial is unknown. In this study, 215 male Sprague-Dawley rats were subjected to embolic stroke and 75 rats were included in the final analysis. The animals were treated with the MMP inhibitor p-aminobenzoyl-gly-pro-D-leu-D-ala-hydroxamate before or after 3 or 6 h of ischemia. Animals were monitored for reperfusion and received rt-PA 6 h after ischemia onset. The results at 24 h showed that MMP inhibition 3 h after ischemia significantly decreased the degree of brain edema (17% of hemispheric enlargement in the treated group versus 24% in controls, P=0.018), reduced the risk (OR=0.163; 95% CI: 0.029 to 0.953) and gravity (0.09 versus 0.19 mg of parenchymal hemoglobin, P=0.02) of intracerebral hemorrhage, and improved neurological outcome (20% of the treated animals had a slight deficit; all of the controls had a bad outcome, P<0.05). Delaying MMP inhibition to 6 h after ischemia restricted the beneficial role of the treatment to a reduction in the risk of parenchymal hemorrhage (OR=0.242; 95% CI: 0.060 to 0.989). Our results confirm the involvement of MMPs in HT and support the possibility of extending the therapeutic window for thrombolysis in stroke by administering a broad-spectrum MMP inhibitor after the onset of ischemia.

Effect of one-shot intravenous 0.42 mega unit urokinase therapy in patients with acute ischemic stroke

We evaluated the efficacy of intravenous (IV) urokinase (UK) treatment for acute ischemic stroke patients. We treated 45 patients with 0.42 mega units of IV UK and 201 patients with other conventional agents. Clinical severity and outcome were evaluated using National Institutes of Health Stroke Scale (NIHSS) scores and modified Rankin scale (mRS). We defined clinical improvement as a reduction of NIHSS score of > 4 points between admission and discharge. The rate of improvement, as defined earlier, was significantly higher in the UK group (27/45; 60%) than in the non-UK group (67/201, 33%) (P = .0009; chi(2) test). The rate of mRS 0-2 (good outcome) on discharge in the UK group (28/45; 62%) was slightly (but not significantly) higher than that in the non-UK group (99/201; 49%). Baseline characteristics, including risk factors, did not differ between the 2 groups, except for time to treatment and length of hospitalization. We conclude that treatment of acute ischemic stroke patients with 0.42 mega units of IV UK shows better clinical improvement than conventional therapy.

[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.

The endovascular management of intracranial vascular disease including the MERCI device

The prompt and aggressive management of acute stroke has become the standard of care as public awareness and the available successful treatment options both increase. The intravenous administration of tissue plasminogen activator within an established treatment window has been determined through large well-designed studies. The endovascular strategies for acute stroke have evolved significantly over the past 5 years and have been prompted by the limits of the intravenous treatment, as well as by the desire to demonstrate improved recanalization rates and improved long-term outcomes. Among these interventional treatment options are the intra-arterial administration of tissue plasminogen activator and newer antiplatelet agents, mechanical thrombectomy with the MERCI device, and intracranial angioplasty and stenting. This article outlines the major studies that have defined the current field of acute stroke management and discusses the basic treatment paradigms that are commonly utilized today.

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.

Accident vasculaire cérébral hémorragique : nouveautés sur la prise en charge

Haemorrhagic stroke is frequent and associated with a high mortality and morbidity. Less than 30% of patients are still alive five years after onset and few patients regain functional independence. The worsening effect of anticoagulation has been demonstrated and the failure to rapidly normalize coagulation further increases haematoma expansion. In a recent phase II trial, recombinant activated factor VII given within 4 hours of stroke onset, reduced haematoma growth, mortality and disability. An aggressive blood pressure and intracranial pressure control early after the haemorrhage seems beneficial. A large prospective randomized study (the STICH trial) did not demonstrate any beneficial effect of surgery.

The use of intravenous recombinant tissue plasminogen activator in acute ischemic stroke

We sought to determine the frequency of use of intravenous (i.v.) recombinant tissue plasminogen activator (rt-PA) in patients presenting to our institution with acute ischemic stroke (AIS). This observational study involved keeping a log of all patients presenting to our institution with symptoms consistent with AIS who were potential candidates for emergency thrombolysis over a 3-year period. The log included brain computed tomography (CT) scan results, whether or not rt-PA was administered, and contraindications to thrombolysis. It also included each patient's time flow through the system, from symptom onset to decision time regarding (and administration of) thrombolytics. Over the 36-month period of the study, there were 142 patients who presented to the Emergency Department (ED) who initially were thought to be potential candidates for thrombolysis for AIS. Ninety-five (68.5%) of these 142 patients had a confirmed diagnosis of AIS. On further clarification of symptom onset, 77 (81%) of these 95 patients with AIS actually presented within 3 h, and 17 (22%) of these 77 patients met criteria for thrombolysis and had no contraindications. All 17 (100%) patients with AIS presenting within 3 h of onset and without contraindications received i.v. rt-PA in the ED. In conclusion, i.v. rt-PA can be administered for AIS within the 3-h window if a hospital is committed to providing this treatment. Thrombolysis remains a treatment for a minority of AIS patients.

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.

[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.

The Evolving Role of Advanced MR Imaging as a Management Tool for Adult Ischemic Stroke: A Western-European Perspective

New and more advanced diagnostic imaging techniques for acute stroke triage have the potential to not only improve the quality of care but also reduce health care costs. Although sufficiently large and methodologically sound studies with regard to cost effectiveness of MR imaging are lacking, the overall impression is that MR imaging has revolutionized not only the diagnosis but also the open and investigational management of neurologically ill patients.

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.

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.

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.

Brain perfusion and ultrasonic imaging techniques

Advances in neurosonology have generated several techniques of ultrasonic perfusion imaging employing ultrasound echo contrast agents (ECAs). Doppler imaging techniques cannot measure the low flow velocities that are associated with parenchymal perfusion. Ultrasonic perfusion imaging, therefore, is a combination of a contrast agent-specific ultrasound imaging technique (CAI) mode and a data acquisition and processing (DAP) technique that is suited to observe and evaluate the perfusion kinetics. The intensity in CAI images is a measure of ECA concentration but also depends on various other parameters, e.g. depth of examination. Moreover, ECAs can be destroyed by ultrasound, which is an artifact but can also be a feature. Thus, many different DAPs have been developed for certain CAI techniques, ECAs and target organs. Although substantial progress in ECA and CAI technology can be foreseen, ultrasound contrast imaging has yet to reliably differentiate between normal and pathological perfusion conditions. Destructive imaging techniques, such as contrast burst imaging (CBI) or time variance imaging (TVI), in combination with new DAP techniques provide sufficient signal-to-noise ratio (SNR) for transcranial applications, and consider contrast agent kinetics and destruction to eliminate depth dependency and to calculate semi-quantitative parameters. Since ultrasound machines are widely accessible and cost-effective, ultrasonic perfusion imaging techniques should become supplementary standard perfusion imaging techniques in acute stroke diagnosis and monitoring. This paper gives an overview on different CAI and DAP techniques with special focus on recent innovations and their clinical potential.

Development of thrombolytic therapy for stroke: a perspective

Thrombolysis with tissue plasminogen activator (alteplase, Activase trade mark, rtPA; Genentech Inc) has proven beneficial for acute stroke management, even though only 1 - 2% of stroke patients in the US are treated with the drug [1]. Part of the reason for the under utilisation of alteplase may be the narrow therapeutic window and frequent occurrence of serious side effects, such as increased haemorrhage incidence [2,3]. It is because of these shortcomings, that recent efforts have attempted to identify new thrombolytics that might improve the benefit/risk ratio in treating stroke. Second generation derivatives of alteplase have attempted to counteract the side effects of the drug by increasing fibrin specificity (tenecteplase, TNK-tPA; Genentech Inc) or half-life (lanoteplase, SUN-9216; Genetics Institute Inc.). New recombinant DNA methodology has led to the revival of plasmin or a truncated form of plasmin (microplasmin; ThromboGenics Ltd), a direct-acting thrombolytic with non-thrombolytic related neuroprotective activities, as a therapeutic. Other promising approaches for the treatment of stroke include the development of novel plasminogen activators, such as recombinant desmodus rotundus salivary plasminogen activator (rDSPA) alpha-1 (Schering/Teijin Pharmaceuticals) and a mutant fibrin-activated human plasminogen (BB10153; British Biotech Inc.). These important areas of drug discovery and development will be reviewed.

Comparison of CT and CT angiography source images with diffusion-weighted imaging in patients with acute stroke within 6 hours after onset

BACKGROUND AND PURPOSE

Although stroke MRI has advantages over other diagnostic imaging modalities in acute stroke patients, most of these individuals are admitted to emergency units without MRI facilities. There is a need for an accurate diagnostic tool that rapidly and reliably detects hemorrhage, extent of ischemia, and vessel status and potentially estimates tissue at risk. We sought to determine the diagnostic accuracy of the combination of non-contrast-enhanced CT, CT angiography (CTA), and CTA source images (CTA-SI, showing early parenchymal contrast enhancement) in comparison with a multiparametric stroke MRI protocol in patients with acute stroke within 6 hours after onset.

METHODS

Non-contrast-enhanced CT, CTA, stroke MRI including diffusion-weighted imaging (DWI), and MR angiography (MRA) were performed in patients with symptoms of acute stroke within 6 hours after onset. We analyzed infarct volumes on days 1 and 5 as shown on CTA-SI, DWI, and T2-weighted images (Wilcoxon, Mann-Whitney, Spearman tests), estimated the collateral status, and assessed clinical outcome (modified Rankin Scale, Barthel Index, National Institutes of Health Stroke Scale, Scandinavian Stroke Scale).

RESULTS

We analyzed the data of 20 stroke patients who underwent CT and MRI scanning within 6 hours (mean, 2.83 and 3.38 hours, respectively). Vessel occlusion was present in 16 of 20 patients. CTA-SI volumes did not differ from DWI volumes (P=0.601). Furthermore, the CTA-SI lesion volumes significantly correlated with the initial DWI lesion volumes (P<0.0001, r=0.922) and with outcome lesion volumes (P=0.013 r=0.736). Patients with poor collaterals experienced infarct growth (P=0.0058) and had a significantly worse clinical outcome (all P<0.012); patients with good collaterals did not (P=0.176).

CONCLUSIONS

The combination of non-contrast-enhanced CT (exclusion of intracranial hemorrhage), CTA (vessel status), and early contrast-enhanced CTA-SI (demarcation of irreversible infarct) allows diagnostic assessment of acute stroke with a quality comparable to that of stroke MRI. Furthermore, it is possible to distinguish patients at risk of infarct growth from those who are not according to the collateral status, in analogy with the stroke MRI mismatch concept.

CT and diffusion-weighted MR imaging in randomized order: diffusion-weighted imaging results in higher accuracy and lower interrater variability in the diagnosis of hyperacute ischemic stroke

BACKGROUND AND PURPOSE

Diffusion-weighted MRI (DWI) has become a commonly used imaging modality in stroke centers. The value of this method as a routine procedure is still being discussed. In previous studies, CT was always performed before DWI. Therefore, infarct progression could be a reason for the better result in DWI.

METHODS

All hyperacute (<6 hours) stroke patients admitted to our emergency department with a National Institutes of Health Stroke Scale (NIHSS) score >3 were prospectively randomized for the order in which CT and MRI were performed. Five stroke experts and 4 residents blinded to clinical data judged stroke signs and lesion size on the images. To determine the interrater variability, we calculated kappa values for both rating groups.

RESULTS

A total of 50 patients with ischemic stroke and 4 patients with transient symptoms of acute stroke (median NIHSS score, 11; range, 3 to 27) were analyzed. Of the 50 patients, 55% were examined with DWI first. The mean delay from symptom onset until CT was 180 minutes; that from symptom onset until DWI was 189 minutes. The mean delay between DWI and CT was 30 minutes. The sensitivity of infarct detection by the experts was significantly better when based on DWI (CT/DWI, 61/91%). Accuracy was 91% when based on DWI (CT, 61%). Interrater variability of lesion detection was also significantly better for DWI (CT/DWI, kappa=0.51/0.84). The assessment of lesion extent was less homogeneous on CT (CT/DWI, kappa=0.38/0.62). The differences between the 2 modalities were stronger in the residents' ratings (CT/DWI: sensitivity, 46/81%; kappa=0.38/0.76).

CONCLUSIONS

CT and DWI performed with the same delay after onset of ischemic stroke resulted in significant differences in diagnostic accuracy. DWI gives good interrater homogeneity and has a substantially better sensitivity and accuracy than CT even if the raters have limited experience.

Ethics and consent to treat issues in acute stroke therapy

Consent to treat with thrombolytic therapy for acute ischemic stroke presents an ethical dilemma for hospitals, physicians, patients, and their families. This article presents four aspects of this controversial topic and provides recommendations for conditions that allow for ethical consent to treat.

Management of acute stroke

Acute stroke is a medical emergency. The outcome is influenced by the rapidity and quality of initial care, which is best delivered by specialists with appropriate facilities, including 24 h access to computed tomography. Stroke management requires attention to simple details and has been summarised in clinical guidelines. General measures include control of blood glucose concentration, temperature, fluid balance, and oxygenation. Blood-pressure management is a matter for continuing research. Aspirin should be started early in ischaemic stroke, but heparin has doubtful value; antiembolism stockings may be preferable. Thrombolysis has a substantial benefit in selected circumstances, and trials continue to examine a wider role. Neuroprotection remains experimental, though magnesium is potentially of interest. Early neurosurgery has a role limited to decompression of lesions in the posterior fossa but is under trial for large hemispheric infarcts and moderate intracerebral bleeds.