Thrombolytic therapy in stroke: possibilities and hazards

Bleeding from an Unruptured Cerebral Aneurysm following the Local Intra-arterial Administration of Urokinase: A Case Report

A 57-year-old woman with a wide-necked anterior communicating artery (Acom) aneurysm underwent stent-assisted coiling (SAC) due to aneurysm enlargement. Dual antiplatelet therapy was initiated 7 days before the operation, and systemic heparinization was performed while maintaining an activated clotting time (ACT) of approximately 300 s during the procedure. SAC was performed using a laser-cut closed-cell stent and bare platinum coils. At the end of the procedure, the Acom and right anterior cerebral artery (ACA) were occluded by in-stent thrombosis. Following local intra-arterial administration of 480000 U of urokinase, the Acom and right ACA were recanalized, accompanied by extravasation around the Acom aneurysm. A computed tomography (CT) scan revealed a right frontal hematoma, which did not enlarge after the administration of protamine sulfate. The hematoma disappeared spontaneously, and the patient recovered without any neurological deficits. Local administration of urokinase is an effective treatment for in-stent thrombosis. However, because the devices for SAC may cause mechanical injuries to the aneurysms, urokinase should be used cautiously for cerebral aneurysms, even if unruptured.

Thrombolytic Therapy in Acute Stroke

Purpose:

To report the safety and efficacy of local, direct, intra-arterial and intravenous fibrinolysis treatment in selected cases of clinically symptomatic patients with acute occlusion of the intracranial cerebral arteries and dural sinuses.

Methods:

Patients with acute progressive neurological deterioration, in spite of systemic anticoagulation and/or antiplatelet medications, presenting with occlusion of a major intracranial cerebral artery or dural sinus were treated. From a transfemoral approach through a guiding catheter, a 2.5F microcatheter was guided directly into the intracranial cerebral circulation and embedded within the clot. Infusion of urokinase was then performed directly into the thrombus until lysis was attained.

Results:

In 36 total patients, 27 cases were treated for an acute arterial occlusion in 45 vascular territories. Clinically, there was neurological improvement in 18 (66.7%) cases. Complications directly related to therapy included symptomatic intracranial hemorrhage in three cases (11.1%), which included 1 case (3.7%) of vessel perforation. In 8 (29.6%) patients, there was no evidence of clinical improvement, and in long-term follow-up there were 9 (33.3%) patient deaths. Nine patients were treated for an intracerebral dural sinus thrombosis in ten vascular territories by local urokinase infusion. In 7 (77.8%) cases, there was angiographic evidence of clot lysis and clinical improvement of the patient's neurological condition. Minor complications including infection and noncerebral sites of bleeding occurred in 3 (33.3%) patients, requiring adjustment in urokinase infusion therapy.

Conclusions:

Local, direct intra-arterial or intravenous infusion of thrombolytic drugs for treatment of stroke patients may improve overall patient morbidity and mortality related to acute thromboembolic disease in the central nervous system. Further clinical studies are warranted to evaluate this form of therapy.

Recommendations for preclinical research in hemorrhagic transformation

Hemorrhagic transformation (HT) is an important complication of ischemic stroke and is responsible for most of the mortality associated with acute reperfusion therapy. Although many important publications address the preclinical models of ischemic stroke, there are no current recommendations on the conduct of research aimed at understanding the mechanisms and consequences of HT. The purpose of this review is to present the various models used in HT research, the clinical correlates, and the experimental variables known to influence the quantitation of HT in preclinical investigation. Lastly, recommendations for the conduct of preclinical research in HT are provided.

Evolving role of endovascular treatment of acute ischemic stroke

The perceived advantages of endovascular treatment for acute ischemic stroke in terms of recanalization, the multimodal and targeted approaches, and perhaps the more permissive rules on devices than on medications for their licensing favored the assumption that endovascular treatment is superior to intravenous thrombolysis for acute treatment of ischemic stroke, and its adoption in more advanced stroke centers. However, this assumption has been questioned by recent clinical trial experience showing that endovascular treatment is not superior to intravenous thrombolysis. The new evidence has changed the perception and the importance of conducting randomized trials in this area. This summary examines the background and outcomes of the latest experience with endovascular techniques in acute stroke treatment based on historical data. The new challenge is how to study the latest generation of devices called stent retrievers, which are faster in recanalizing and easier to use, in selected patients with acute ischemic stroke. In the meantime, the available evidence does not provide support for the use of endovascular treatment of acute ischemic stroke in clinical practice.

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.

Randomized trial of frequent low-efficiency and short hemodialysis/hemofiltration in hemodialysis patients with acute brain injury

PURPOSE

The aim of the study was to compare effects of frequent low-efficiency and short hemodialysis (FLESHD) and frequent low-efficiency and short hemofiltration (FLESHF) in hemodialysis (HD) patients with acute brain injury (ABI).


METHODS

We randomly divided 13 HD patients with ABI into FLESHD (n = 6) or FLESHF (n = 7) groups. Conditions for the first to third sessions were as follows.

FLESHD

intravenous administration of glycerol 400 ml/session, blood flow rate (QB) 100 ml/min, dialysate flow rate 300 ml/min, and treatment duration 2 h (HD-1).

FLESHF

intravenous administration of glycerol 400 ml/session, QB 150 ml/min, substitution flow rate 10 l/session, and treatment duration 4 h (HF-1). After the fourth session, we gradually changed the conditions and stopped glycerol administration (HD-2 and HF-2).


RESULTS

There were no significant differences in survival rate, consciousness level, or adverse effects during hospitalization in either group. In mixed model analysis, the level of HCO3- post FLESHF was significantly (p<0.0001) increased compared with the level post FLESHD. However, no significant differences were seen in the levels of osmolality, in blood pressure before and after either dialysis method, or in the level of HCO3- pre dialysis. The variation in the relative ratio of BUN before FLESHF was significantly higher (p<0.05) than the relative ratio before FLESHD in the sixth session. In the FLESHD groups, serum sodium was higher and serum potassium was lower than in the FLESHF groups.


CONCLUSIONS

FLESHD with glycerol under these conditions may be a better therapeutic option for managing patients with ABI, although the short-term survival rate is similar.

Hemostasis and alterations of the central nervous system

Modulation of coagulation has been successfully applied to ischemic disorders of the central nervous system (CNS). Some components of the coagulation system have been identified in the CNS, yet with limited exception their functions have not been clearly defined. Little is known about how events within the cerebral tissues affect hemostasis. Nonetheless, the interaction between cerebral cells and vascular hemostasis and the possibility that endogenous coagulation factors can participate in functions within the neurovascular unit provide intriguing possibilities for deeper insight into CNS functions and the potential for treatment of CNS injuries. Here, we consider the expression of coagulation factors in the CNS, the coagulopathy associated with focal cerebral ischemia (and its relationship to hemorrhagic transformation), the use of recombinant tissue plasminogen activator (rt-PA) in ischemic stroke and its study in animal models, the impact of rt-PA on neuron and CNS structure and function, and matrix protease generation and matrix degradation and hemostasis. Interwoven among these topics is evidence for interactions of coagulation factors with and within the CNS. How activation of hemostasis occurs in the cerebral tissues and how the brain responds are difficult questions that offer many research possibilities.

Extension of ischemic therapeutic time window by a free radical scavenger, Edaravone, reperfused with tPA in rat brain

3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone) is a free radical scavenger. We tested the hypothesis that combination treatment of Edaravone and recombinant tissue plasminogen activator (tPA) extends the therapeutic time window. Male Wistar rats were subjected to 1.5-, 3.0- or 4.5-hour middle cerebral artery (MCA) occlusion (MCAO) by a nylon thread. Animals were randomly divided into four groups. The Sham group rats were operated without MCAO and drug injection. In the Vehicle-treated group the same volume of saline was given every 1.5 hours from just after MCAO to just before reperfusion. In the Vehicle + tPA-treated group saline injection was given as above and tPA (5 mg/kg, i.v.) was given once just after reperfusion. Edaravone+tPA-treated group: Edaravone (3 mg/kg, i.v.) was given every 1.5 hours instead of saline and tPA injection as above. Survival rate, infarct size and evidence of apoptosis and hemorrhage were examined in the animals. Combining administration of Edaravone+tPA significantly increased survival rate after 3 hours of transient MCAO, and reduced infarct volume after 1.5 hours of transient MCAO compared with the vehicle or vehicle+tPA groups. In Edaravone+tPA-treated group, the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) and 4-hydroxynonenal (4-HNE) positive cells were reduced at 16 hours after 3 hours of transient MCAO, but not in advanced glycation end products (AGEs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Hemorrhage rate and the area decreased in the Edaravone+tPA-treated group. The combination therapy of Edaravone+tPA increased survival rate, and reduced the infarct volume and hemorrhage with reduction of lipid peroxidation. Therefore, Edaravone combination is expected to extend the therapeutic time window of tPA in the clinical situation.

Plasminogen activators and ischemic stroke: conditions for acute delivery

Appropriate acute treatment with plasminogen activators (PAs) can significantly increase the probability of minimal or no disability in selected ischemic stroke patients. There is a great deal of evidence showing that intravenous recombinant tissue PAs (rt-PA) infusion accomplishes this goal, recanalization with other PAs has also been demonstrated in the development of this treatment. Recanalization of symptomatic, documented carotid or vertebrobasilar arterial territory occlusions have also been achieved by local intra-arterial PA delivery, although only a single prospective double-blinded randomized placebo-controlled study has been reported. The increase in intracerebral hemorrhage with these agents by either delivery approach underscores the need for careful patient selection, dose-appropriate safety and efficacy, proper clinical trial design, and an understanding of the evolution of cerebral tissue injury due to focal ischemia. Principles underlying the evolution of focal ischemia have been expanded by experience with acute PA intervention. Several questions remain open that concern the manner in which PAs can be applied acutely in ischemic stroke and how injury development can be limited.

Toward the Neurovascular Unit A Journey in Clinical Translation

The Nobel laureate Max Delbrück often said that it is the crossover between disciplines where advances are possible in science. This certainly has been true for our understanding of the vascular biology of the central nervous system in the setting of ischemic stroke. The ability to cross the boundaries of hemostasis, neurology, hematology, and neuroscience has facilitated our research direction to define the relation of the microvasculature to neuron function. Work begun with the clinical scientific exploration of the contributions of arterial thrombosis to the acute injury processes initiated by focal cerebral ischemia has led to an increased understanding of the effects of ischemia on microvessel integrity.

Stroke attributable to acute basilar occlusion

Acute basilar artery occlusion carries a high risk of disabling stroke or death. Fast recanalization of the vessel is the mainstay of the therapy. Recanalization may be achieved by intravenous or intra-arterial administration of thrombolytics. These procedures are currently used as life-saving interventions, despite the low level of evidence supporting their efficacy, because of the bad prognosis of the disease. Intravenous thrombolysis may be started earlier, but it is less often used, mainly for historic reasons; intra-arterial measures are possibly more effective in achieving recanalization but require extra time before they can be started and demand a considerable amount of resources. The basilar artery does not recanalize in approximately one third of patients; this result has not been modified over the past two decades by these treatments and probably will not change. Combined mechanical and intra-arterial thrombolysis may be more efficient in achieving basilar artery recanalization, but the impact of this combined intervention on the final outcome has not been evaluated. Because time is critical, as in every stroke, implementation of a specific treatment protocol for this condition, including one of the aforementioned treatments, and eventual transfer to a secondary-care unit will save time and improve prognosis.

Intravenous thrombolytics for ischemic stroke

For many decades, intravenous (IV) thrombolytics have been delivered to treat acute thrombosis. Although these medications were originally effective for coronary thrombosis, their mechanisms have proven beneficial for many other disease processes, including ischemic stroke. Treatment paradigms for acute ischemic stroke have largely followed those of cardiology. Specifically, the aim has been to recanalize the occluded artery and to restore perfusion to the brain that remains salvageable. To that end, rapid clot lysis was sought using thrombolytic medicines already proven effective in the coronary arteries. IV-thrombolysis for ischemic stroke began its widespread adoption in the late 1990s after the publication of the National Institute of Neurological Disorders and Stroke study. Since that time, other promising IV-thrombolytics have been developed and tested in human trials, but as of yet, none have been proven better than a placebo. Adjunctive treatments are also being evaluated. The challenge remains balancing reperfusion and salvaging brain tissue with the potential risks of brain hemorrhage.

Molecular Mechanisms in the Pathogenesis and Treatment of Acute Ischemic Stroke

The management of acute ischemic stroke has not made significant strides since the introduction of recombinant tissue plasminogen activator (r-TPA) two decades ago. The use of other therapies, such as heparin, aspirin, dipyridamole, and/or clopidogrel, have only moderately aided in the treatment of this ischemic disease. Therefore, major medical innovative approaches are critically needed. Because of the side effects associated with r-TPA (specifically bleeding) and its limited 3-h therapeutic window, new studies using current developments encountered in the molecular biology of ischemia are being incorporated into the potential therapy of ischemic stroke. A review of the major advances in the field, including glutamate receptor blockade, magnesium infusion, inflammation blockade, apoptosis inhibition, and other therapies, is introduced with special emphasis on the molecular findings recognized as targets for a better and more effective treatment. As new therapies are being considered, the time of administration is becoming a central point of study for the application of novel therapeutic initiatives.

Safety and efficacy of alteplase in the treatment of acute ischemic stroke

After publication of the results of the National Institute of Neurological Disorders and Stroke study, the application of intravenous thrombolysis for ischemic stroke was launched and has now been in use for more than 10 years. The approval of this drug represented only the first step of the therapeutic approach to this pathology. Despite proven efficacy, concerns remain regarding the safety of recombinant tissue-type plasminogen activator for acute ischemic stroke used in routine clinical practice. As a result, a small proportion of patients are currently treated with thrombolytic drugs. Several factors explain this situation: a limited therapeutic window, insufficient public knowledge of the warning signs for stroke, the small number of centers able to administer thrombolysis on a 24-hour basis and an excessive fear of hemorrhagic complications. The aim of this review is to explore the clinical efficacy of treatment with alteplase and consider the hemorrhagic risks.

Diagnostic criteria and quality control of the registration of stroke events in the MONICA project

Stroke events are being registered in 27 of the MONICA collaborating centres. Coding of test cases has shown the greatest discrepancies in coding of the type of stroke (different pathoanatomical diagnoses) and of the diagnostic category (whether a definite stroke has occurred or not), 23% and 14% discrepancies respectively. A check for completeness of stroke registration at the Northern Sweden MONICA Center showed that more than 91% of the events were retrieved by routine registration procedures. Measures to reduce the discrepancies in coding between centres and to check for completeness of data are suggested. In many centres, the number of stroke events below 65 years of age is too small to permit meaningful analyses. By including also stroke events in the 65-74 year age range, the number of fatal events in the Northern Sweden MONICA area increased by 195% and non-fatal events by 149%. Many other MONICA centres have also extended their upper age limit for the registration of stroke events, thus improving the preconditions for statistical evaluations of the long-term changes in stroke incidence.

Plasma level of IL-6 and its relationship to procoagulant and fibrinolytic markers in acute ischemic stroke

Procoagulant or impaired fibrinolytic states as well as inflammatory reactions mediated by cytokines are likely involved in the pathogenesis of acute ischemic stroke. We examined the potential relationship between interleukin 6 (IL-6) and hemostatic markers. The procoagulant and fibrinolytic states were assessed in 46 patients with acute stroke by measuring plasma levels of plasminogen activator inhibitor-1 (PAI-1), thrombin-antithrombin complex (TAT), and plasminogen-antiplasmin complex (PAP). Circulating IL-6 levels were measured using ELISA (Quantikine, R and D systems, MN, USA). Circulating IL-6 (mean, 26.5 pg/mL) and PAI-1 (mean, 19.9 ng/mL) levels were higher in patients with acute stroke than in healthy subjects (mean, 3.0 pg/mL, 10.4 ng/mL, respectively). TAT levels were statistically different according to the etiologic subtypes of stroke (atherogenic, 2.5 ng/mL; lacunar 3.2 ng/mL; cardiogenic 9.9 ng/mL, p = 0.021). Neither procoagulant levels nor fibrinolytic markers significantly correlated with circulating IL-6 levels. Our findings suggest that elevated proinflammatory cytokines during the initial hours of ischemic stroke may be an independent pathogenic factor or a consequence of the thrombotic event with no relationship to the procoagulant or fibrinolytic states.

Hyperacute therapy of acute ischemic stroke: intraarterial thrombolysis and mechanical revascularization strategies

Ischemic stroke is a major cause of morbidity and mortality. Despite the fact that it is the third most common cause of death in the United States, there is only one FDA approved treatment for patients. This is Intravenous recombinant tissue plasminogen activator given within 3 hours of symptom onset. Furthermore, despite the approval of this drug, it has been underutilized in the community. The limited time window of 3 hours disqualifies many patients from receiving the drug. In addition, fears of intracranial hemorrhage have resulted in underutilization of the drug in the community setting. Efforts to increase the time window to treatment include utilization of the intraarterial route for delivery of thrombolytic drug and interventional mechanical strategies to revascularize intracranial vessels. In this report we review the major intraarterial thrombolysis trials and review the mechanical strategies being developed to treat patients with acute ischemic stroke.

Recombinant tissue plasminogen activator (rtPA) for stroke. The perspective at 8 years

OBJECTIVE

To review the 8-year experience with recombinant tissue plasminogen activator (rtPA) for stroke, with commentary on ramifications for the approach to stroke treatment, directions in stroke research, and sociological aspects of stroke as a disease of concern in our society.

BACKGROUND

Approved in 1996, rtPA remains the only drug indicated for the treatment of ischemic stroke. Stroke treatment and research have evolved rapidly in response to opportunities and discoveries related to the advent of rtPA. The presence of rtPA has engendered an increased level of awareness about all aspects of stroke.

METHODOLOGY

Literature review was performed, focusing on topics that in the author's view are of greatest relevance to the use of rtPA in clinical practice and to the directions in which the presence of rtPA is moving the field of stroke treatment, research, and politics.

RESULTS

Challenges have been raised, and met, regarding the validity of the data upon which the approval for rtPA was based. Limitations in the use of rtPA include the brief time available for treatment, the need for rapid imaging and blood-pressure control, and the fact that large-artery occlusions respond poorly. The major risk of treatment is brain hemorrhage, and although predictors of hemorrhage are known, their presence does not constitute an absolute contraindication to treatment. A virtual subindustry has evolved to enhance the benefit and applicability of rtPA through refined imaging technology and the use of rtPA intra-aterially, as well as in combination with other agents and devices. Sociopolitically, rtPA has elevated the level of awareness of stroke and provided impetus for the stroke center movement and federal legislation to stop stroke.

CONCLUSION

The development of rtPA has been the most effective advance in the field of stroke. It has generated healthy debate regarding the design, performance, and interpretation of stroke trials, including cost-benefit considerations. rtPA has stimulated research in a multitude of areas, enhanced our understanding of stroke pathophysiology, and defined important limits and risks for urgent intervention. rtPA is the cornerstone of the stroke center movement, as well as legislation in behalf of stroke at the congressional level.

Assessment of the patient with hyperacute stroke: imaging and therapy

Neuroimaging is an important part of the assessment of patients with hyperacute stroke. As new treatments that may reverse cerebral ischemia have been developed, the role of neuroimaging has changed from simply anatomic depiction of early infarction to identification, by means of physiologic (rather than simply anatomic) information, of regions that are at risk for infarction. The goal of such imaging techniques is to monitor successes and complications of recently developed treatments such as thrombolysis.

Essential role of endogenous tissue plasminogen activator through matrix metalloproteinase 9 induction and expression on heparin-produced cerebral hemorrhage after cerebral ischemia in mice

Cerebral hemorrhage associated with antithrombotic and thrombolytic therapy in acute stroke continues to present a major clinical problem. Rupture of the cerebral microvasculature involves the degradation and remodeling of extracellular matrix. Here we demonstrated that the delayed administration of heparin 3 hours after photothrombotic middle cerebral artery occlusion (MCAO) caused cerebral hemorrhage in wild-type (WT) mice but not in tissue plasminogen activator (tPA)-deficient knockout (KO) mice. Heparin administration increased tPA activity and its mRNA expression at 6 and 12 hours after MCAO in the ischemic hemispheres of WT mice. The expression of tPA was enhanced in microglial cells in the ischemic border zone. We also observed an exacerbation of matrix metalloproteinase (MMP) 9 expression at the mRNA level and its conversion to an active form after heparin administration in the ischemic hemisphere in WT mice but not in tPA KO mice. The increased MMP 9 expression was localized in microglial cells and endothelial cells. These findings suggest that endogenous tPA, through the enhancement of MMP 9 expression and proteolytic activation, plays an essential role in the pathogenesis of heparin-produced cerebral hemorrhage. Targeting tPA, MMP 9, or both may provide a new approach for preventing cerebral hemorrhage associated with antithrombotic therapy for stroke in humans.

Antiactin-targeted immunoliposomes ameliorate tissue plasminogen activator-induced hemorrhage after focal embolic stroke

Thrombolytic stroke therapy with tissue plasminogen activator (tPA) is limited by serious risks of intracerebral hemorrhage. In this study, the authors show that a novel antiactin-targeted immunoliposome significantly reduced tPA-induced hemorrhage in an established rat model of embolic focal stroke. Spontaneously hypertensive rats were subjected to focal ischemia using homologous blood clot emboli. Delayed administration of tPA (10 mg/kg, 6 hours after ischemia) induced intracerebral hemorrhage at 24 hours. In control rats treated with tPA plus vehicle, hemorrhage volumes were 9.0 +/- 2.4 uL (n = 7). In rats treated with tPA plus antiactin immunoliposomes, hemorrhage volumes were significantly reduced to 4.8 +/- 2.7 uL (n = 8, P < 0.05). No significant effects were seen when rats were treated with tPA plus a nontargeted liposome (7.8 +/- 2.1 uL, n = 9). Fluorescent immunohistochemistry showed that rhodamine-labeled targeted liposomes colocalized with vascular structures in ischemic brain that stained positive for endothelial barrier antigen, a marker of cerebral endothelial cells. These data suggest that immunoliposomes may ameliorate vascular membrane damage and reduce hemorrhagic transformation after thrombolytic therapy in cerebral ischemia.

Hemorrhagic transformation following ischemic stroke: significance, causes, and relationship to therapy and treatment

Hemorrhagic transformation (HT) is a frequent consequence of ischemic stroke that becomes more prevalent after thrombolytic therapy. Despite concerns about safety parameters, thrombolytic drugs remain the first course of action available to clinicians for stroke management. However, recent efforts in preclinical studies have attempted to discover other drugs that can lessen the risk of hemorrhage associated with thrombolytic administration. This review focuses on three classes of pharmacologic agents that have shown some promise in animal models of stroke, and can thus be considered as possible candidates for coadministration with thrombolytics in the treatment of stroke. These include the following: 1) spin trap agents, such as alpha-phenyl-N-t-butylnitrone (PBN) that scavenge free radicals; 2) matrix metalloproteinase (MMP) inhibitors, such as BB-94, that prevent membrane and vessel remodeling following ischemia; and 3) the novel glycoprotein (GP) IIb/IIIa platelet receptor antagonist SM-20302. Although these drugs affect different mechanisms, the common denominator seemed to be their effectiveness in reducing the incidence of hemorrhage in response to thrombolytic infusion following an embolic stroke.

Controversies about tissue plasminogen activator: extending the window of therapy

The management of stroke has undergone significant development over the past 15 years. Perhaps the single most important landmark has been the approval by the Food and Drug Administration of intravenous (IV) tissue plasminogen activator (t-PA) for the treatment of ischemic stroke. However, the approval of this drug has not met with unanimous support by the medical community and, at present, only a minority of stroke patients receive t-PA. Although this is partly due to the fact that many patients do not meet criteria for treatment with IV t-PA, others simply do not arrive at medical facilities sufficiently early to be safely managed using thrombolysis. The appropriate use of IV t-PA in the treatment of ischemic stroke requires proper selection of patients and strict adherence to clinical protocols of treatment. The ideal stroke patient for treatment with IV t-PA is one who suffers occlusion of a small artery that leads to a disabling deficit.

Emergency stenting to treat neurological complications occurring after carotid endarterectomy

OBJECTIVES

The purpose of this study was to assess the efficacy of emergency stent implantation for the treatment of perioperative stroke after carotid endarterectomy (CEA).

BACKGROUND

Carotid endarterectomy has been proven safe and effective in reducing the risk of stroke in symptomatic and asymptomatic patients with >60% carotid artery stenosis. However, perioperative stroke has been reported in 1.5% to 9% of CEA cases. The management of such a complication is challenging. Recently, percutaneous transluminal carotid angioplasty with stent deployment has emerged as a valuable and alternative strategy for the treatment of carotid artery disease.

METHODS

Between April 1998 and February 2000, 18 of the 995 patients (1.8%) who had CEA in our institution experienced perioperative major or minor neurological complications. Of these, 13 patients underwent emergency carotid angiogram and eventual stent implantation, whereas the remaining five had surgery re-exploration.

RESULTS

Carotid angiogram was performed within 20+/-10 min and revealed vessel flow-limiting dissection (five cases) or thrombosis (eight cases). Percutaneous transluminal carotid angioplasty with direct stenting (self-expandable stent) was performed in all 13 cases. Angiographic success was 100%. Complete remission of neurological symptoms occurred in 11 of the 13 patients treated by stent implantation and in one of the five patients treated by surgical re-exploration (p = 0.024).

CONCLUSIONS

Stent implantation seems to be a safe and effective strategy in the treatment of perioperative stroke complicating CEA, especially when carotid dissection represents the main anatomic problem.

Selective Intra-arterial Thrombolysis for Embolic Complications of Cerebral Endovascular Therapy

SUMMARY

Cerebral thrombo-embolic complications seldom occur during intracranial endovascular therapeutic procedures. Yet, despite a systemic preventive regimen of pre-operative intravenous acetylsalicylic acid and effective systemic heparinisation, we encountered seven complications of this type over a period of five years, a 3.7 per thousand incidence (7/1858). Local intra-arterial thrombolysis performed immediately after the thrombo-embolic complication resulted in complete recanalization in five cases and partial recanalization in two. CT scans performed 24 hours after thrombolysis were normal in six of the seven patients. Only one female patient with partial recanalization showed a limited cortical infarct in the parietal distribution of the middle cerebral artery territory. In all seven cases recanalization of the occluded vessel resulted in a return to the baseline initial neurological status. This short series demonstrates the usefulness of emergent thrombolysis dealing with the thrombo-embolic complications of angiography or endovascular therapy. These results are in agreement with these experimental data showing that early recanalization can prevent macroscopically visible infarcts.

Antithrombotic treatments in acute ischemic stroke

Ischemic stroke results most commonly from cerebral arterial thrombosis. Antithrombotic agents can reduce the incidence of cerebral embolic events or the extent of tissue injury and neurological outcome. The antiplatelet agents aspirin, ticlopidine, and the combination of dipyridamole and aspirin are associated with a significant reduction in second focal cerebral ischemic events. Oral anticoagulants have a role to reduce the incidence of cardiogenic emboli in patients with mechanical cardiac valves or nonvalvular atrial fibrillation. Both antithrombotics are untested in the acute setting. The recombinant tissue plasminogen activator rt-PA has been shown to significantly increase the number of stroke patients with no or minimal deficit when treated within 3 hours of symptom onset. Additional studies of this and other plasminogen activators by both intravenous and intra-arterial delivery have highlighted limitations to this approach, but also support its role in acute intervention. The risk of intracerebral hemorrhage attends the use of all antithrombotic agents, most notably plasminogen activators. Strategies to decrease this risk are likely to add to beneficial outcome.

Reduction of tissue plasminogen activator-induced hemorrhage and brain injury by free radical spin trapping after embolic focal cerebral ischemia in rats

Thrombolytic stroke therapy with tissue plasminogen activator (tPA) remains complicated by serious risks of cerebral hemorrhage and brain injury. In this study, a novel model of tPA-induced hemorrhage was used in spontaneously hypertensive rats to examine the correlates of hemorrhage, and test methods of reducing hemorrhage and brain injury. Homologous blood clot emboli were used to occlude the middle cerebral artery in spontaneously hypertensive rats, and delayed administration of tPA (6 hours postischemia) resulted in high rates of cerebral hemorrhage 24 hours later. Compared with untreated rats, tPA significantly increased hemorrhage volumes by almost 85%. Concomitantly, infarction and neurological deficits were worsened by tPA. A parallel experiment in normotensive Wistar-Kyoto rats showed markedly reduced rates of hemorrhage, and tPA did not significantly increase hemorrhage volumes. To examine whether tPA-induced hemorrhage was caused by the delayed onset of reperfusion per se, another group of spontaneously hypertensive rats was subjected to focal ischemia using a mechanical method of arterial occlusion. Delayed (6 hours) reperfusion via mechanical means did not induce hemorrhage. However, administration of tPA plus delayed mechanical reperfusion significantly increased hemorrhage volumes. Since reperfusion injury was implicated, a final experiment compared outcomes in spontaneously hypertensive rats treated with tPA plus the free radical spin trap alpha-phenyl tert butyl nitrone (alpha-PBN) versus tPA alone. tPA-induced hemorrhage volumes were reduced by 40% with alpha-PBN, and infarction and neurological deficits were also decreased. These results indicate that (1) blood pressure is an important correlate of tPA-induced hemorrhage, (2) tPA interacts negatively with reperfusion injury to promote hemorrhage, and (3) combination therapies with anti-free radical treatments may reduce the severity of tPA-induced hemorrhage and brain injury after cerebral ischemia.

Dynamics of cerebral injury, perfusion, and blood-brain barrier changes after temporary and permanent middle cerebral artery occlusion in the rat

By means of magnetic resonance imaging (MRI) we longitudinally monitored the evolution of ischemic injury, changes in cerebral hemodynamics and alterations of the blood-brain barrier (BBB) during permanent or temporary middle cerebral artery occlusion (MCAO) in rats. Using the intraluminal suture occlusion model, male Sprague-Dawley rats were subjected to either permanent MCAO (Group A, n = 6), reperfusion after 1 h (Group B, n = 5), or reperfusion after 3 h (Group C, n = 5). Diffusion- and perfusion-weighted MRI and Gd-DTPA enhanced T1-weighted images were performed at six time points from 0.5 to 6 h post-MCAO. The lesion volume increased progressively in group A, decreased significantly in group B (P<0.01), and only showed a tendency toward reduction in group C. Perfusion-weighted MRI delineated severe perfusion deficits in the ischemic core, confirmed early and late reperfusion, and was able to demonstrate postischemic hyperperfusion in group C. Gd-DTPA extravasation was found in all animals with permanent MCAO and initially became grossly visible between 4.5 and 6 h post-MCAO. While only 2 animals demonstrated contrast enhancement in group B, widespread BBB changes were detected immediately following late reperfusion (Group C). Our results demonstrate that with advanced MRI techniques, alterations of the BBB can be correlated with the hemodynamic and biophysical consequences of reperfusion.

Case presentations of neuroradiologic interventions for acute cerebrovascular disease

The treatment options and management of ischemic and hemorrhagic stroke are expanding. Neuroradiologic interventions are being used in acute care settings to change the course of these devastating processes. These interventions include the injection of intra-arterial urokinase for ischemic stroke, use of coils to secure aneurysms, and balloon angioplasty for increasing the lumen of spastic cerebral arteries in patients with cerebral vasospasm. Using a case study approach, these three options for managing stroke patients will be integrated, and nursing strategies for delivering care to the stroke patient will be profiled.

Interventional use of plasminogen activators in central nervous system diseases

Still an experimental approach, the direct intra-arterial infusion of plasminogen activators in the setting of acute thrombotic stroke has received impetus from successful clinical trials of intravenous infusion therapy. Direct therapy, employing catheter delivery, has successfully produced evidence of recanalization in carotid artery territory and vertebrobasilar artery territory thrombotic occlusions. One very recent prospective randomized study has demonstrated the success and limitations of this approach. Attention to safety concerns will be important to the future success of direct intra-arterial delivery of plasminogen activators in acute thrombotic stroke.

Thrombolytic therapy in the treatment of stroke

Approximately 80 to 90% of cerebral ischaemic events that occur within 24 hours of symptom onset are due to atherothrombotic or thromboembolic occlusions. This forms the rationale for the use of thrombolytic agents in patients with acute ischaemic stroke. Early studies determined that recanalisation occurred in approximately 21 to 72% of patients with occluded cerebral arteries after intra-arterial or intravenous administration of streptokinase, urokinase, alteplase (recombinant tissue-type plasminogen activator; rt-PA) or duteplase (a 2-chain rt-PA). Initial reports suggested that frequencies of haemorrhagic transformation and parenchymatous haematoma in the carotid territory were similar whether patients with middle cerebral artery stroke received thrombolysis via intra-arterial or intravenous administration. The Multicentre Acute Stroke Trial-Europe (MAST-E), the Australia Streptokinase (ASK), and the Multicentre Acute Stroke Trial-Italy (MAST-I) trials, which evaluated intravenous streptokinase 1.5 x 10(6) IU in patients with acute ischaemic stroke, were terminated prematurely because of excessive early mortality and symptomatic intracranial haemorrhage in streptokinase recipients compared with those treated with placebo. However, those studies had not been preceded by dose-ranging trials. Intravenous administration of alteplase 0.9 mg/kg within 3 hours [National Institute of Neurological Disorders and Stroke (NINDS) trial], or 1.1 mg/kg within 6 hours [European Cooperative Acute Stroke Study (ECASS)], of symptom onset in patients with acute ischaemic stroke resulted in an absolute 11 to 13% treatment-associated improvement in clinical measurement scales; such as the modified Rankin scale and Barthel index, compared with placebo recipients. In the ECASS trial, those results were limited to a 'target population' restricted to those who satisfied all entry criteria. In both trials, the frequency of symptomatic haemorrhage was greater in patients treated with alteplase than with placebo and reinforced the importance of careful patient selection. Strict patient selection remains central to the success of this approach.

Intra-arterial thrombolysis in acute ischaemic stroke: experience with a superselective catheter embedded in the clot

OBJECTIVES

To report experience of intra-arterial thrombolysis for acute stroke, performed with a microcatheter navigated into the intracranial circulation to impale the clot.

METHODS

Patients were selected on the following criteria: (1) clinical examination suggesting a large vessel occlusion in stroke patients between 18 and 75 years; (2) no radiographic signs of large actual ischaemia on CT at admission; (3) angiographically documented occlusion of the middle cerebral artery (MCA) stem or of the basilar artery (BA), without occlusion of the ipsilateral extracranial internal carotid artery or of both the vertebral arteries; (4) end of the entire procedure within six hours of stroke. 12 patients with acute stroke were recruited, eight of whom had occlusion of the MCA stem and four of the BA. Urokinase was used as the thrombolytic agent.

RESULTS

Complete recanalisation in six MCA stem and in two BA occurred, and partial recanalisation in two MCA stem and one BA. There was no recanalisation in one BA. A clinically silent haemorrhage occurred in two patients, and a parenchymal haematoma in one patient, all in MCA occlusions. At four months five patients achieved self sufficiency (four with MCA and one with BA occlusion). Six patients were dependent (three totally), and one died.

CONCLUSIONS

The strict criteria of eligibility allowing the enrollment of very few patients and the procedure itself, requiring particular neuroradiological expertise, make this procedure not routine. Nevertheless, the approach can be considered a possible option for patients with acute ischaemic stroke.

Acute stroke

Disruption of cerebral blood flow may influence brain energy metabolism to produce reversible or irreversible neurologic deficits. The emergency physician is in a unique position to provide timely treatment during the first few hours of an acute stroke. He or she must be facile with unique pharmacologic and non-pharmacologic treatment designed for the stroke patient concerning ventilation, blood pressure, and circulation.

Management of acute stroke

Preview Regardless of cause, acute stroke is a devastating illness that demands immediate treatment to contain neurologic damage, plus long-term management to assure utmost rehabilitation. In this article, the authors describe the features of stroke from various causes and discuss current therapy.

Thrombolytic therapy in acute stroke

PURPOSE

To report the safety and efficacy of local, direct, intra-arterial and intravenous fibrinolysis treatment in selected cases of clinically symptomatic patients with acute occlusion of the intracranial cerebral arteries and dural sinuses.

METHODS

Patients with acute progressive neurological deterioration, in spite of systemic anticoagulation and/or antiplatelet medications, presenting with occlusion of a major intracranial cerebral artery or dural sinus were tested. From a transfemoral approach through a guiding catheter, a 2.5F microcatheter was guided directly into the intracranial cerebral circulation and embedded within the clot. Infusion of urokinase was then performed directly into the thrombus until lysis was attained.

RESULTS

In 36 total patients, 27 cases were treated for an acute arterial occlusion in 45 vascular territories. Clinically, there was neurological improvement in 18 (66.7%) cases. Complications directly related to therapy included symptomatic intracranial hemorrhage in three cases (11.1%), which included 1 case (3.7%) of vessel perforation. In 8 (29.6%) patients, there was no evidence of clinical improvement, and in long-term follow-up there were 9 (33.3%) patient deaths. Nine patients were treated for an intracerebral dural sinus thrombosis in ten vascular territories by local urokinase infusion. In 7 (77.8%) cases, there was angiographic evidence of clot lysis and clinical improvement of the patient's neurological condition. Minor complications including infection and noncerebral sites of bleeding occurred in 3 (33.3%) patients, requiring adjustment in urokinase infusion therapy.

CONCLUSION

Local, direct intra-arterial or intravenous infusion of thrombolytic drugs for treatment of stroke patients may improve overall patient morbidity and mortality related to acute thromboembolic disease in the central nervous system. Further clinical studies are warranted to evaluate this form of therapy.

Acute stroke intervention with intraarterial urokinase infusion

PURPOSE

A preliminary evaluation of the efficacy and safety of treating patients with acute stroke with intraarterial urokinase infusions was performed.

PATIENTS AND METHODS

Twelve patients with acute stroke were treated within 8 hours of symptom onset (average, 5 hours). Thrombolysis was performed within the middle cerebral (n = 10), internal carotid (n = 1), and basilar (n = 1) arteries. Urokinase (160,000-500,000 IU) was infused through microcatheters placed into or adjacent to the thrombi.

RESULTS

Thrombolysis was angiographically successful in nine patients (75%), all of whom had long-term neurologic improvement. No or minimal neurologic deficits were present in six patients (50%). Thrombolysis failed in three patients (25%); one patient died and two developed severe permanent neurologic deficits. No hemorrhagic complications occurred.

CONCLUSION

Preliminary results suggest that intraarterial urokinase infusion may be effective and safe for treating patients with acute stroke. Potentially devastating neurologic damage was averted or lessened in nine patients (75%). No additional neurologic damage was caused by intervention in the remaining three patients (25%).