Effect of the Glycine Antagonist Gavestinel on cerebral infarcts in acute stroke patients, a randomized placebo-controlled trial: The GAIN MRI Substudy

Multimodal CT imaging characteristics may predict post-reperfusion infarct volume in wake-up stroke patients

Background

Accurate prediction of subsequent infarct volume in acute ischemic stroke (AIS) patients helps determine appropriate interventions and prognosis. The objectives are to assess whether early multimodal CT imaging characteristics of wake-up stroke (WUS) patients could predict post-reperfusion infarct volume and evaluate the accuracy of baseline infarct and penumbra volumes for predicting follow-up infarct volume.

Methods

This retrospective study included WUS patients, last seen well (LSW) >6 h, with multimodal CT imaging at baseline. Baseline non-contrast CT (NCCT) and CT perfusion were analyzed using RAPID software, and CT angiography using maximum intensity projection. Post-reperfusion infarct volume was assessed at 24-h following reperfusion on magnetic resonance diffusion-weighted imaging (DWI). Patients were stratified by treatment module for analyses.

Results

Of 34 eligible patients, 9 (26.5%) received intravenous recombinant tissue plasminogen activator (r-tPA) alone and 25 (73.5%) received both endovascular thrombectomy (EVT) and r-tPA. All patients had a strong correlation between baseline NCCT alberta stroke program early CT score, clot burden score (CBS), Tan score, infarct volume, penumbra volume with 24-h post-reperfusion infarct volume (respectively, r=0.172, P=0.015; r=0.118, P=0.047; r=0.149, P=0.024; r=0.311, P=0.001 and r=0.120; P=0.045). Among reperfusion therapies, WUS patients who received EVT had a significantly lower 24-h post-reperfusion infarct volume and had a significant difference between baseline infarct volume and 24-h post-reperfusion infarct volume (respectively, 82 vs. 14, P=0.032 and 47 vs. 14, P=0.04).

Conclusions

Primarily obtained multimodal CT imaging characteristics may predict post-reperfusion infarct volume in WUS patients, and those who underwent EVT had a significantly lower post-reperfusion infarct volume.

Pulsed Electromagnetic Fields: A Novel Attractive Therapeutic Opportunity for Neuroprotection After Acute Cerebral Ischemia

OBJECTIVES

Acute cerebral ischemia is characterized by several pathological processes evolving during time, which contribute to the final tissue damage. Secondary processes, such as prolonged inflammatory response, impaired mitochondrial function and oxidative stress, are responsible for the progression of brain injury to the peri-infarct area, called "penumbra." Adenosine has been shown to play a crucial role in regulating the inflammatory cascade following brain ischemia. Pulsed electromagnetic fields (PEMFs) act as modulators of adenosine receptors, increasing the functionality of the endogenous adenosine. In particular, PEMF exposure induces a significant upregulation of A_2A and A₃ adenosine receptors in different neuronal cell types. Several lines of evidence suggest that PEMF exposure might play a neuroprotective role after ischemic damage.

MATERIALS AND METHODS

This review summarizes the current knowledge on the mechanism of action of PEMFs and their biological effects on neuronal damage both in preclinical and clinical studies.

RESULTS

PEMFs counteract hypoxia-induced apoptosis and ROS production in neuronal-like cells and exert a strong anti-inflammatory effect on microglial cells. Data from stroke animal models showed that PEMFs exposure is able to reduce the size of the infarct area and decrease the levels of pro-inflammatory mediators. In clinical studies, PEMFs stimulation proved to be safe and well tolerated. Preliminary results on acute ischemic stroke patients showed a dose-dependent reduction in the lesion size.

CONCLUSIONS

Altogether, these data demonstrate the efficacy of PEMFs against several mechanisms underlying ischemic damage and suggest that PEMFs might represent a novel noninvasive adjunctive treatment for acute ischemic stroke, providing neuroprotection and reducing functional deficits following ischemia.

The Negative Allosteric Modulator EU1794-4 Reduces Single-Channel Conductance and Ca2+ Permeability of GluN1/GluN2A N-Methyl-d-Aspartate Receptors

NMDA receptors are ligand-gated ion channels that mediate a slow, Ca²⁺-permeable component of excitatory synaptic currents. These receptors are involved in several important brain functions, including learning and memory, and have also been implicated in neuropathological conditions and acute central nervous system injury, which has driven therapeutic interest in their modulation. The EU1794 series of positive and negative allosteric modulators of NMDA receptors has structural determinants of action near the preM1 helix that is involved in channel gating. Here, we describe the effects of the negative allosteric modulator EU1794-4 on GluN1/GluN2A channels studied in excised outside-out patches. Coapplication of EU1794-4 with a maximally effective concentration of glutamate and glycine increases the fraction of time the channel is open by nearly 1.5-fold, yet reduces single-channel conductance by increasing access of the channel to several subconductance levels, which has the net overall effect of reducing the macroscopic current. The lack of voltage-dependence of negative modulation suggests this is unrelated to a channel block mechanism. As seen with other NMDA receptor modulators that reduce channel conductance, EU1794-4 also reduces the Ca²⁺ permeability relative to monovalent cations of GluN1/GluN2A receptors. We conclude that EU1794-4 is a prototype for a new class of NMDA receptor negative allosteric modulators that reduce both the overall current that flows after receptor activation and the flux of Ca²⁺ ion relative to monovalent cations. SIGNIFICANCE STATEMENT: NMDA receptors are implicated in many neurological conditions but are challenging to target given their ubiquitous expression. Several newly identified properties of the negative allosteric modulator EU1794-4, including reducing Ca²⁺ flux through NMDA receptors and attenuating channel conductance, explain why this modulator reduces but does not eliminate NMDA receptor function. A modulator with these properties could have therapeutic advantages for indications in which attenuation of NMDA receptor function is beneficial, such as neurodegenerative disease and acute injury.

A multicenter, randomized trial on neuroprotection with remote ischemic per-conditioning during acute ischemic stroke: the REmote iSchemic Conditioning in acUtE BRAin INfarction study protocol

Rationale Remote ischemic per-conditioning-causing transient limb ischemia to induce ischemic tolerance in other organs-reduces final infarct size in animal stroke models. Aim To evaluate whether remote ischemic per-conditioning during acute ischemic stroke (<6 h) reduces brain infarct size at 24 h. Methods and design This study is being performed in five French hospitals using a prospective randomized open blinded end-point design. Adults with magnetic resonance imaging confirmed ischemic stroke within 6 h of symptom onset and clinical deficit of 5-25 according to National Institutes of Health Stroke Scale will be randomized 1:1 to remote ischemic per-conditioning or control (stratified by center and intravenous fibrinolysis use). Remote ischemic per-conditioning will consist of four cycles of electronic tourniquet inflation (5 min) and deflation (5 min) to a thigh within 6 h of symptom onset. Magnetic resonance imaging is repeated 24 h after stroke onset. Sample size estimates For a difference of 15 cm³ in brain infarct growth between groups, 200 patients will be included for 5% significance and 80% power. Study outcomes The primary outcome will be the difference in brain infarct growth from baseline to 24 h in the intervention versus control groups (by diffusion-weighted image magnetic resonance imaging). Secondary outcomes include: National Institutes of Health Stroke Scale score absolute difference between baseline and 24 h, three-month modified Rankin score and daily living activities, mortality, and tolerance and side effects of remote ischemic per-conditioning. Discussion The only remote ischemic per-conditioning trial in humans with stroke did not show remote ischemic per-conditioning to be effective. REmote iSchemic Conditioning in acUtE BRAin INfarction, which has important design differences, should provide more information on the use of this intervention in patients with acute ischemic stroke.

Cortical spreading depolarization: Pathophysiology, implications, and future directions

Cortical spreading depolarization (CSD) is a spreading loss of ion homeostasis, altered vascular response, change in synaptic architecture, and subsequent depression in electrical activity following an inciting neurological injury. First described by Leão in 1944, this disturbance in neuronal electrophysiology has since been demonstrated in a number of animal studies, and recently a few human studies that examine the occurrence of this depolarizing phenomenon in the setting of a variety of pathological states, including migraines, cerebrovascular accidents, epilepsy, intracranial hemorrhages, and traumatic brain injuries. The onset of CSD has been demonstrated experimentally following a disruption in the neuronal environment leading to glutamate-induced toxicity. This initial event leads to pathological changes in the activity of ion channels that maintain membrane potential. Recovery mechanisms such as sodium-potassium pumps that aim to restore homeostasis fail, leading to osmolar shifts of fluid, swelling of the neuron, and ultimately a measurable depression in cortical activity that spreads in the order of millimeters per minute. Equally important is the resulting change in vascular response. In healthy tissue, increased electrical activity is coupled with release of vasodilatory factors such as nitric oxide and arachidonic acid metabolites that increase local blood flow to meet increased energy expenditure. In damaged tissue, not only is the restorative vascular response lacking but a vasoconstrictive response is promoted and the ischemia that follows adds to the severity of the initial injury. Tissue threatened by this ischemic response is then at elevated risk for CSD propagation and falls into a vicious cycle of electrical and hemodynamic disturbance. Efforts have been made to halt this spreading cortical depression using N-methyl-D-aspartate receptor antagonists and other ion channel blockers to minimize the damaging effects of CSD that can persist long after the triggering insult.

Understanding history, and not repeating it. Neuroprotection for acute ischemic stroke: from review to preview

BACKGROUND

Neuroprotection for ischemic stroke is a growing field, built upon the elucidation of the biochemical pathways of ischemia first studied in the 1970s. Beginning in the early 1990s, means by which to pharmacologically intervene and counteract these pathways have been sought, though with little clinical success. Through a comprehensive review of translations from laboratory to clinic, we aim to evaluate individual mechanisms of action, while highlighting potential barriers to success that will guide future research.

METHODS

The MEDLINE database and The Internet Stroke Center clinical trials registry were queried for trials involving the use of neuroprotective agents in acute ischemic stroke in human subjects. For the purpose of the review, neuroprotective agents refer to medications used to preserve or protect the potentially ischemic tissue after an acute stroke, excluding treatments designed to re-establish perfusion. This excludes mechanical or pharmacological thrombolytics, anti-thrombic medications, or anti-platelet therapies.

RESULTS

This review summarizes previously trialed neuroprotective agents, including but not limited to glutamate neurotransmission blockers, anti-oxidants, GABA agonists, leukocyte migration blockers, various small cation channel modulators, narcotic antagonists, and phospholipid membrane stabilizers. We outline key biochemical steps in ischemic injury that are the proposed areas of intervention. The agents, time to administration of therapeutic agent, follow-up, and trial results are reported.

DISCUSSION

Stroke trials in humans are burdened with a marked heterogeneity of the patient population that is not seen in animal studies. Also, trials to date have included patients that are likely treated at a time outside of the window of efficacy for neuroprotective drugs, and have not effectively combined thrombolysis with neuroprotection. Through an evaluation of the accomplishments and failures in neuroprotection research, we propose new methodologies, agents, and techniques that may provide new routes for success.

Final infarct volume estimation on 1-week follow-up MR imaging is feasible and is dependent on recanalization status

PURPOSE

We aim to characterize infarct volume evolution within the first month post-ischemic stroke and to determine the effect of recanalization status on early infarct volume estimation.

METHODS

Ischemic stroke patients recruited for the MONITOR and VISION studies were retrospectively screened and patients who had infarcts on diffusion-weighted imaging (DWI) at baseline and had at least two follow-up MR scans (n = 56) were included. Pre-defined target imaging time points, obtained on a 3-T MR scanner, were 12 hours (h), 24 h, 7 days, and ≥30 days post-stroke. Infarct tissue was manually traced blinded to the images at the other time points. Infarct expansion index was calculated by dividing infarct volume at each follow-up time point by the baseline DWI infarct volume. Recanalization was assessed within 24 h post-stroke. Correlation and statistical comparison analysis were done using the Spearman, Mann-Whitney, and Kruskal-Wallis tests.

RESULTS

Follow-up infarct volumes were positively correlated with the baseline infarct volume (ρ > 0.81; p < 0.001) where the strongest correlation existed between baseline and 7-day post-stroke infarct volumes (ρ = 0.92; p < 0.001). The strongest correlation among the follow-up imaging was found between infarct volumes 7-day post-stroke and ≥30-day time points (ρ = 0.93; p < 0.001). Linear regression showed a close-to unity slope between 7-day and final infarct volumes (slope = 1.043; p < 0.001). Infarct expansion was higher in the non-recanalized group than the recanalized group at the 7-day (p = 0.001) and ≥30-day (p = 0.038) time points.

CONCLUSIONS

Final infarct volume can be approximated as early as 7 days post-stroke. Final infarct volume approximation is significantly associated with recanalization status.

Safety, tolerability and pharmacokinetics of MCI-186 in patients with acute ischemic stroke: new formulation and dosing regimen

BACKGROUND AND PURPOSE

MCI-186 (edaravone) is a free radical scavenger approved in Japan since 2001 for the treatment of patients with acute ischemic stroke within 24 h from the onset of symptoms. It was recommended by the Japanese Guidelines for the Management of Stroke 2004. Our aim was to investigate the safety, tolerability and pharmacokinetics of a new formulation and dose regimen (intravenous bolus plus infusion) of MCI-186 suitable for the treatment of acute ischemic stroke in Europe because the Japanese treatment protocol includes twice-a-day intravenous infusion of MCI-186 for a maximum of 14 days. Such a treatment protocol is not very practical in Europe, where hospital stay is much shorter in acute hospitals.

METHODS

In a double-blind, placebo-controlled randomized clinical trial we studied two dosing regimens, each in a cohort of 18 patients. Patients were randomized in a 2:1 ratio in both cohorts to receive MCI-186 or placebo. Review of safety and plasma concentration data from the first cohort (loading dose 0.08 mg/kg + 0.2 mg/kg/h infusion) preceded the second cohort (loading dose 0.16 mg/kg + 0.4 mg/kg/h infusion). Safety parameters included adverse events, severe adverse events, physical examinations, local reactions at infusion site, ECG, clinical chemistry and hematology, modified Total Neuropathy Score and CT scans.

RESULTS

Mean age and National Institutes of Health Stroke Scale (NIHSS) score on admission of patients in cohorts 1 and 2 and the placebo group were 64, 63, and 69 years and 5, 5, and 6, respectively. The number of treatment emergent adverse events that occurred was 109, most of which were transient, mild or moderate. Both doses of the new formulation and dosing regimen were well tolerated. After the initiation of the infusion, plasma concentrations of MCI-186 reached or exceeded prespecified target levels within 24 h in both MCI-186 cohorts, which were in the putative therapeutic range in humans. Geometric mean values of MCI-186 plasma concentration at the end of the infusion in cohorts 1 and 2 were 391 and 1,595 ng/ml, respectively.

CONCLUSIONS

The primary objective of the present study, safety and tolerability of the new formulation and dosing regimen, was achieved. The new formula and both dosing regimens were well tolerated and achieved intended plasma concentrations suitable for larger safety studies before pivotal trials.

Cyclin-dependent kinase inhibition with roscovitine: neuroprotection in acute ischemic stroke

Stroke is the third most common cause of mortality and the leading cause of disability in industrialized country. According to population based-studies, ischemic stroke accounts for 67-80% of all strokes. Thrombolysis is used during the acute phase in only 2-5% of ischemic patients. Clinical trials of candidate neuroprotective agents have failed to identify viable therapies for ischemic stroke in humans. There is therefore a great need for new therapeutic strategies, considering that not all brain cells die immediately after ischemic stroke.

The role of glutamate in neuronal ischemic injury: the role of spark in fire

Although being a physiologically important excitatory neurotransmitter, glutamate plays a pivotal role in various neurological disorders including ischemic neurological diseases. Its level is increased during cerebral ischemia with excessive neurological stimulation causing the glutamate-induced neuronal toxicity, excitotoxicity, and this is considered the triggering spark in the ischemic neuronal damage. The glutamatergic stimulation will lead to rise in the intracellular sodium and calcium, and the elevated intracellular calcium will lead to mitochondrial dysfunction, activation of proteases, accumulation of reactive oxygen species and release of nitric oxide. Interruption of the cascades of glutamate-induced cell death during ischemia may provide a way to prevent, or at least reduce, the ischemic damage. Various therapeutic options are suggested interrupting the glutamatergic pathways, e.g., inhibiting the glutamate synthesis or release, increasing its clearance, blocking of its receptors or preventing the rise in intracellular calcium. Development of these strategies may provide future treatment options in the management of ischemic stroke.

Increased concentrations of both NMDA receptor co-agonists D-serine and glycine in global ischemia: a potential novel treatment target for perinatal asphyxia

Worldwide, perinatal asphyxia is an important cause of morbidity and mortality among term-born children. Overactivation of the N-methyl-d-aspartate receptor (NMDAr) plays a central role in the pathogenesis of cerebral hypoxia–ischemia, but the role of both endogenous NMDAr co-agonists d-serine and glycine remains largely elusive. We investigated d-serine and glycine concentration changes in rat glioma cells, subjected to oxygen and glucose deprivation (OGD) and CSF from piglets exposed to hypoxia–ischemia by occlusion of both carotid arteries and hypoxia. We illustrated these findings with analyses of cerebrospinal fluid (CSF) from human newborns affected by perinatal asphyxia. Extracellular concentrations of glycine and d-serine were markedly increased in rat glioma cells exposed to OGD, presumably through increased synthesis from l-serine. Upon reperfusion glycine concentrations normalized and d-serine concentrations were significantly lowered. The in vivo studies corroborated the finding of initially elevated and then normalizing concentrations of glycine and decreased d-serine concentrations upon reperfusion These significant increases of both endogenous NMDAr co-agonists in combination with elevated glutamate concentrations, as induced by global cerebral ischemia, are bound to lead to massive NMDAr activation, excitotoxicity and neuronal damage. Influencing these NMDAr co-agonist concentrations provides an interesting treatment target for this common, devastating and currently poorly treatable condition.

The ischemic penumbra: correlates in imaging and implications for treatment of ischemic stroke. The Johann Jacob Wepfer award 2011

The concept of the ischemic penumbra was formulated 30 years ago based on experiments in animal models showing functional impairment and electrophysiological disturbances with decreasing flow to the brain below defined values (the threshold for function) and irreversible tissue damage with the blood supply further decreased (the threshold for infarction). The perfusion range between these thresholds was termed 'penumbra', and restitution of flow above the functional threshold was able to reverse the deficits without permanent damage. However, in further experiments, the dependency of the development of irreversible lesions on the interaction of the severity and duration of critically reduced blood flow was established - proving that the lower the flow, the shorter the time for efficient reperfusion. Therefore, infarction develops from the core of ischemia to the areas of less severe hypoperfusion. The propagation of irreversible tissue damage is characterized by a complex cascade of interconnected electrophysiological, molecular, metabolic and perfusional disturbances. Waves of depolarizations, the peri-infarct spreading depression-like depolarizations, inducing activation of ion pumps and liberation of excitatory transmitters, have dramatic consequences as drastically increased metabolic demand cannot be satisfied in regions with critically reduced blood supply. The translation of experimental concept into the basis for efficient treatment of stroke requires non-invasive methods by which regional flow and energy metabolism can be repeatedly investigated to demonstrate penumbra tissue that can benefit from therapeutic interventions. Positron emission tomography (PET) allows the quantification of regional cerebral blood flow, the regional metabolic rate for oxygen and the regional oxygen extraction fraction. From these variables, clear definitions of irreversible tissue damage and critically perfused but potentially salvageable tissue (i.e. the penumbra) can be achieved in animal models and stroke patients. Additionally, further tracers can be used for early detection of irreversible tissue damage, e.g. by the central benzodiazepine receptor ligand flumazenil. However, PET is a research tool and its complex logistics limit clinical routine applications. As a widely applicable clinical tool, perfusion/diffusion-weighted (PW/DW) MRI is used, and the 'mismatch' between the PW and the DW abnormalities serve as an indicator of the penumbra. However, comparative studies of PW/DW-MRI and PET have pointed to an overestimation of the core of irreversible infarction as well as of the penumbra by MRI modalities. Some of these discrepancies can be explained by unselective application of relative perfusion thresholds, which might be improved by more complex analytical procedures. Heterogeneity of the MRI signatures used for the definition of the mismatch are also responsible for disappointing results in the application of PW/DW-MRI for the selection of patients for clinical trials. As long as a validation of the mismatch selection paradigm is lacking, its use as a surrogate marker of outcome is limited.

Final cerebral infarct volume is predictable by MR imaging at 1 week

BACKGROUND AND PURPOSE

Stroke volume, an increasingly used end point in phase II trials, is considered stationary at least 30 days after the ictus. We investigated whether information conveyed by MR imaging measurements of the "final" infarct volume could be assessed as early as the subacute stage (days 3-6), rather than waiting for the chronic stage (days 30-45).

MATERIALS AND METHODS

Ninety-five patients with middle cerebral artery stroke prospectively included in a multicenter study underwent MR imaging during the first 12 hours (MR imaging-1), between days 3 and 6 (MR imaging-2), and between days 30 and 45 (MR imaging-3). We first investigated the relationship between subacute (FLAIR-2) and chronic volumes (FLAIR-3), by using a linear regression model. We then tested the relationship between FLAIR volumes (either FLAIR-2 or FLAIR-3) and functional disability, measured by the mRS at the time of MR imaging-3, by using logistic regression. The performances of the models were assessed by using the AUC in ROC.

RESULTS

A linear association between log FLAIR-2 and log FLAIR-3 volumes was observed. The proportion of FLAIR-3 variation, explained by FLAIR-2, was high (R(2) = 81%), without a covariate that improved this percentage. Both FLAIR-2 and FLAIR-3 were independent predictors of mRS (OR, 0.79 and 0.73; 95% CI, 0.64-0.97 and 0.56-0.96; P = .026 and .023). The performances of the models for the association between either FLAIR volume and mRS did not differ (AUC = 0.897 for FLAIR-2 and 0.888 for FLAIR-3).

CONCLUSIONS

Stroke damage may be assessed by a subacute volume because subacute volume predicts the "true" final volume and provides the same clinical prognosis.

Stromal-derived factor-1[alpha] correlates with circulating endothelial progenitor cells and with acute lesion volume in stroke patients

BACKGROUND AND PURPOSE

Endothelial progenitor cells (EPC) are important participants of neovascularization and are mobilized through signaling with stromal-derived factor (SDF-1α), vascular endothelial growth factor (VEGF), granulocyte colony-stimulating factor, and stem cell factor. The association between EPC levels and these growth factors (GF) in acute stroke has not been previously established. We aimed to determine the association between EPC and these GF, and to elucidate a relationship between these GF and stroke severity in acute stroke patients.

METHODS

Seventeen patients were selected from 175 patients with imaging-confirmed acute ischemic stroke. EPC were quantified using CD34, CD133, and VEGF-R2 markers. Plasma VEGF, SDF-1α, granulocyte colony-stimulating factor, and stem cell factor were determined by enzyme-linked immunosorbent assay on days 1 and 3, and brain MRI was performed at baseline and on days 1 and 5 after the stroke onset.

RESULTS

Levels of SDF-1α strongly (r=0.6) correlated with the numbers of EPC subsets CD133(+)VEFG-R2(+) (P<0.004), CD34(+)VEGF-R2(+) (P<0.01), and CD34(+)CD133(+)VEGF-R2(+) (P<0.01) on day 1. Stem cell factor strongly (r=0.5) correlated with CD133(+)VEGF-R2(+) (P<0.05). SDF-1α moderately inversely (r=-0.49) correlated with baseline diffusion-weighted imaging lesion volumes (P<0.04). Median levels of SDF-1α (1561 pg/mL) increased (P<0.04) on day 3 compared to day 1 (1379 pg/mL). Similarly, VEGF at day 3 (95 pg/mL) increased (P<0.03) compared to day 1 (64 pg/mL).

CONCLUSIONS

These results indicate that SDF-1α and stem cell factor correlate with an increase in EPC early in ischemic stroke patients.

The beta-hCG+erythropoietin in acute stroke (BETAS) study: a 3-center, single-dose, open-label, noncontrolled, phase IIa safety trial

BACKGROUND AND PURPOSE

Animal data suggest the use of beta-human chorionic gonadotropin followed by erythropoietin to promote brain repair after stroke. The current study directly translated these results by evaluating safety of this sequential growth factor therapy through a 3-center, single-dose, open-label, noncontrolled, Phase IIa trial.

METHODS

Patients with ischemic stroke 24 to 48 hours old and National Institutes of Health Stroke Scale score of 6 to 24 started a 9-day course of beta-human chorionic gonadotropin (once daily on Days 1, 3, and 5 of study participation) followed by erythropoietin (once daily on Days 7, 8, and 9 of study participation). This study also evaluated performance of serially measured domain-specific end points.

RESULTS

A total of 15 patients were enrolled. Two deaths occurred, neither related to study medications. No safety concerns were noted among clinical or laboratory measures, including screening for deep vein thrombosis and serial measures of serum hemoglobin. In several instances, domain-specific end points provided greater insight into impairments as compared with global outcome measures.

CONCLUSIONS

Results support the safety of this sequential, 2-growth factor therapy initiated 24 to 48 hours after stroke onset.

CT angiography source images predict final infarct extent in patients with basilar artery occlusion

BACKGROUND AND PURPOSE

The posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) is a 10-point grading system to quantify ischemic changes in the posterior circulation. We analyzed whether pc-ASPECTS on CT angiography (CTA) source images (CTASI) predicted the final infarct extent and hemorrhagic transformation (HT) rate in patients with basilar artery occlusion.

MATERIALS AND METHODS

A pc-ASPECTS score of 10 indicates absence of visible ischemic changes in the posterior circulation, and pc-ASPECTS score of 0 indicates ischemic changes in the midbrain, pons, and bilateral thalami, posterior circulation territories, and cerebellar hemispheres. We retrospectively studied patients with basilar artery occlusion on CTA within 24 hours from symptom onset. We applied pc-ASPECTS to noncontrast CT (NCCT), CTASI, and follow-up images by 3-reader-consensus and assessed HT on follow-up images. We calculated Spearman correlation coefficients and performed linear regression analysis. Final infarct extent and HT rates were compared across dichotomized CTASI pc-ASPECTS groups (>/= 8 vs < 8).

RESULTS

Among 43 patients, median (range) onset to CTA time was 5.0 hours (range, 0.7-24 hours). Pc-ASPECTS on CTASI (r = 0.75; P < .001) but not NCCT (r = 0.29; P = .063) correlated with pc-ASPECTS on follow-up scans. Linear regression demonstrated a significant positive relationship between pc-ASPECTS on CTASI and follow-up scans (R(2) = 0.58; P < 01). Median follow-up pc-ASPECTS was lower in patients with a CTASI pc-ASPECTS < 8 compared with patients with a CTASI pc-ASPECTS of 8 or more, respectively (P < .001). HT rates were 27.3% vs 9.5%, respectively (P = .24). None of 8 patients without thrombolysis had HT on follow-up scans.

CONCLUSIONS

The extent of hypoattenuation on CTASI predicts the final infarct extent in patients with basilar artery occlusion.

Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication: A scientific statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke (Part 1)

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the postcardiac arrest syndrome are potentially treatable.

Efficacy and safety of ginsenoside-Rd for acute ischaemic stroke: a randomized, double-blind, placebo-controlled, phase II multicenter trial

BACKGROUND AND PURPOSE

Ginsenoside-Rd is a selective competitive Ca2+ receptor antagonist. A phase II randomized, double-blind, placebo-controlled, multicenter study was conducted to examine the efficacy and safety of ginsenoside-Rd in patients with acute ischaemic stroke.

METHODS

A total of 199 patients were randomized equally to receive a 14-day infusion of placebo (group B), ginsenoside-Rd 10 mg (group A) or ginsenoside-Rd 20 mg (group C). Primary end-points were National Institutes of Health Stroke Scale (NIHSS) scores at 15 days. Secondary end-points were NIHSS scores and the Barthel Index at 8 days, the Barthel Index and the modified Rankin scale at 15 days and 90 days. The safety end-points included serious and non-serious adverse events, laboratory values and vital signs. Analysis was by intention to treat.

RESULTS

For the primary study outcome, there is significant difference amongst the three groups at 15 days in NIHSS scores (P = 0.0003). Comparing group A with B and group B with C, the difference in the mean for NIHSS was significant in statistics (P = 0.0004, P = 0.0009 respectively). This is no significant difference between group A and C (P = 0.9640). For the secondary study outcome, ginsenoside-Rd did not improve neurological functioning. Incidence of serious and non-serious adverse events was similar amongst the three groups.

CONCLUSIONS

Ginsenoside-Rd may be of some benefit in acute ischaemic stroke.

Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the post-cardiac arrest syndrome are potentially treatable.

Establishing final infarct volume: stroke lesion evolution past 30 days is insignificant

BACKGROUND AND PURPOSE

Lesion volume measured on MRI has been used as an objective surrogate marker for outcome in clinical trials. However, lesion volumes vary over time because of edema and tissue loss. This study aims to determine if lesion volumes measured at 30 and 90 days after ictus significantly differ.

METHODS

We performed a retrospective study of 18 patients who had acute (<24 hours) DWI and follow-up fluid-attenuated inversion recovery imaging at 5, 30, and 90 days. Two expert readers segmented lesions and the mean volumes of both reads were used in all statistical analyses.

RESULTS

Patient age was 65.8 (SD, 13.7) years and median NIHSS at baseline was 11.5. Inter-rater variability for lesion volume measurements was 3.7 (5.8) mL. Acute DWI volume was 19.3 (17.3) mL. Fluid-attenuated inversion recovery volumes for 5, 30, and 90 days were 34.3 (23.5), 18.6 (14.0), and 15.9 (13.8) mL, respectively. These volumes differed significantly (P<0.001). Linear regression revealed a strong correlation (r=0.96; P<0.001) between lesion volumes at 30 and 90 days with a slope that did not vary significantly from 1.0 (P=0.448).

CONCLUSIONS

Lesions continue to evolve between 5 and 90 days, but by 30 days lesion volume approaches final infarct volume. While clinical response is the most meaningful outcome measure, our findings suggest that lesion volumes measured at 30 days may provide a sufficient approximation for final infarct volume for use in early phase clinical trials.

Relationships between infarct growth, clinical outcome, and early recanalization in diffusion and perfusion imaging for understanding stroke evolution (DEFUSE)

BACKGROUND AND PURPOSE

The purpose of this study was to determine the relationships between ischemic lesion growth, recanalization, and clinical response in stroke patients with and without a perfusion/diffusion mismatch.

METHODS

DEFUSE is an open label multicenter study in which 74 consecutive acute stroke patients were treated with intravenous tPA 3 to 6 hours after stroke onset. Magnetic resonance imaging (MRI) scans were obtained before, 3 to 6 hours after, and 30 days after treatment. Lesion growth was defined as the difference between the final infarct volume (30 day FLAIR) and the baseline diffusion lesion. Baseline MRI profiles were used to categorize 44 patients into Mismatch versus Absence of Mismatch subgroups. Early recanalization was assessed in 28 patients with an initial vessel lesion on magnetic resonance angiography. Infarct growth was compared based on whether a favorable clinical response (FCR) occurred and whether early recanalization was achieved.

RESULTS

In the Mismatch subgroup, FCR was associated with less infarct growth P=0.03 and early recanalization was predictive of both FCR (odds ratio: 22, P=0.047) and reduced infarct growth P=0.024. There was no significant relationship between recanalization, infarct growth, and clinical outcome in the Absence of Mismatch subgroup. A threshold of <7 cc of growth had the highest sensitivity and specificity for predicting a FCR in Mismatch patients (odds ratio: 65, P=0.015, sensitivity 82%, specificity 75%).

CONCLUSIONS

In contrast to Absence of Mismatch patients, significant associations between recanalization, reduced infarct growth, and favorable clinical response were documented in patients with a perfusion/diffusion mismatch who were treated with tPA within 3 to 6 hours after stroke onset. These findings support the Mismatch hypothesis but require validation in a larger study.

Clinical pharmacological issues in the development of acute stroke therapies

The demonstration of the ischaemic penumbra in animal models and the effectiveness of reperfusion therapy in humans led to considerable optimism for neuroprotection in acute stroke. Initial experience with failure of phase II and III trials led to the STAIR recommendations for pre-clinical and clinical studies. Review of pre-clinical studies suggests that selection of agents for clinical development may not have been optimal. The neuroprotective agent NXY-059 fulfilled pre-clinical and many clinical STAIR criteria but a second large phase III study failed to demonstrate any benefit. Many of the STAIR criteria have not been fulfilled in the development of recent neuroprotective agents. Other issues not addressed include the use of animal models more reflective of older stroke patients with physiological derangement, demonstration of drug distribution to the proposed site of action in humans, selection of patients with salvageable tissue, achieving very early treatment, refinement of measurement of neurological impairment and disability, and physiological optimization in proof of concept human studies. Increasing the number and quality of clinical centres undertaking acute stroke research, use of surrogate imaging markers and adaptive dose designs in phase II trials could improve the likelihood of identifying an effective neuroprotective. Neuroprotection in acute stroke remains a significant challenge but has not been clearly shown to be ineffective. Given the profound burden of stroke and limited applicability of reperfusion to currently at best 10% patients, further proof of concept studies of neuroprotection remain indicated with careful review of pre-clinical data and more rigorous phase II trial design.

Neuroprotection for ischemic stroke: past, present and future

Neuroprotection for ischemic stroke refers to strategies, applied singly or in combination, that antagonize the injurious biochemical and molecular events that eventuate in irreversible ischemic injury. There has been a recent explosion of interest in this field, with over 1000 experimental papers and over 400 clinical articles appearing within the past 6 years. These studies, in turn, are the outgrowth of three decades of investigative work to define the multiple mechanisms and mediators of ischemic brain injury, which constitute potential targets of neuroprotection. Rigorously conducted experimental studies in animal models of brain ischemia provide incontrovertible proof-of-principle that high-grade protection of the ischemic brain is an achievable goal. Nonetheless, many agents have been brought to clinical trial without a sufficiently compelling evidence-based pre-clinical foundation. At this writing, around 160 clinical trials of neuroprotection for ischemic stroke have been initiated. Of the approximately 120 completed trials, two-thirds were smaller early-phase safety-feasibility studies. The remaining one-third were typically larger (>200 subjects) phase II or III trials, but, disappointingly, only fewer than one-half of these administered neuroprotective therapy within the 4-6h therapeutic window within which efficacious neuroprotection is considered to be achievable. This fact alone helps to account for the abundance of "failed" trials. This review presents a close survey of the most extensively evaluated neuroprotective agents and classes and considers both the strengths and weakness of the pre-clinical evidence as well as the results and shortcomings of the clinical trials themselves. Among the agent-classes considered are calcium channel blockers; glutamate antagonists; GABA agonists; antioxidants/radical scavengers; phospholipid precursor; nitric oxide signal-transduction down-regulator; leukocyte inhibitors; hemodilution; and a miscellany of other agents. Among promising ongoing efforts, therapeutic hypothermia, high-dose human albumin therapy, and hyperacute magnesium therapy are considered in detail. The potential of combination therapies is highlighted. Issues of clinical-trial funding, the need for improved translational strategies and clinical-trial design, and "thinking outside the box" are emphasized.

Interexaminer difference in infarct volume measurements on MRI: a source of variance in stroke research

BACKGROUND AND PURPOSE

The measurement of ischemic lesion volume on diffusion- (DWI) and perfusion-weighted MRI (PWI) is examiner dependent. We sought to quantify the variance imposed by measurement error in DWI and PWI lesion volume measurements in ischemic stroke.

METHODS

Fifty-eight consecutive patients with DWI and PWI within 12 hours of symptom onset and follow-up MRI on >or= day-5 were studied. Two radiologists blinded to each other measured lesion volumes by manual outlining on each image. Interexaminer reliability was evaluated by intraclass correlation coefficients (ICC) and relative paired difference or RPD (ratio of difference between 2 measurements to their mean). The ratio of between-examiner variability to between-subject variability (variance ratio) was calculated for each imaging parameter.

RESULTS

The correlation (ICC) between examiners ranged from 0.93 to 0.99. The median RPD was 10.0% for DWI, 14.1% for mean transit time, 18.9% for cerebral blood flow, 21.0% for cerebral blood volume, 16.8% for DWI/MTT mismatch, and 6.3% for chronic T2-weighted images. There was negative correlation between RPD and lesion volume in all but chronic T2-weighted images. The variance ratio ranged between 0.02 and 0.10.

CONCLUSIONS

Despite high correlation between volume measurements of abnormal regions on DWI and PWI by different examiners, substantial differences in individual measurements can still occur. The magnitude of variance from measurement error is primarily determined by the type of imaging and lesion volume. Minimizing this source of variance will better enable imaging to deliver on its promise of smaller sample size.

Lesion volume change after treatment with tissue plasminogen activator can discriminate clinical responders from nonresponders

BACKGROUND AND PURPOSE

A change in acute-to-chronic lesion volume has been proposed as a biomarker for stroke therapies. The objectives of this study were to determine the magnitude of lesion volume change after standard treatment with tissue plasminogen activator and to determine whether specific volume change thresholds can discriminate clinical responders from nonresponders.

METHODS

We measured lesion volume on diffusion weighted at baseline and on 90-day fluid attenuated inversion recovery MRI and scored 3-month modified Rankin Scale in consecutive patients treated with tissue plasminogen activator. We identified variables associated with excellent (modified Rankin Scale 0 to 1) and independent (modified Rankin Scale 0 to 2) outcomes.

RESULTS

We included 53 patients (mean age 69 years, median baseline National Institutes of Health Stroke Scale score 7). The mean acute-to-chronic lesion volume increase was 11.7 (+/-7.7) cm(3). In 23 patients, the chronic lesion was smaller than the baseline lesion. At 3 months, 32 patients had an excellent clinical outcome. Dichotomous volume change variables associated with outcome included decrease in volume >or=30% (P=0.004) and volume increase >or=5 cm(3) (P=0.002).

CONCLUSIONS

In patients given standard tissue plasminogen activator therapy, changes in lesion volume are associated with clinical outcome, and threshold lesion volumes can differentiate excellent and poor outcome, suggesting these as a potential marker of outcome.

Clinical diagnosis of lacunar stroke in the first 6 hours after symptom onset: analysis of data from the glycine antagonist in neuroprotection (GAIN) Americas trial

BACKGROUND AND PURPOSE

Although the pathophysiological heterogeneity of stroke may be highly relevant to the development of acute-phase therapies, discriminating between ischemic stroke subtypes soon after onset remains a challenge. We conducted a study of the accuracy of a clinical diagnosis of lacunar stroke in the first 6 hours after symptom onset.

METHODS

We analyzed data from 1367 patients in the Glycine Antagonist In Neuroprotection (GAIN) Americas trial. The Trial of ORG10172 in Acute Stroke Treatment (TOAST) category "small vessel (lacunar)" disease at day 7 or at hospital discharge was used as the reference standard to determine the accuracy of a diagnosis of a lacunar stroke made within 6 hours of symptom onset using the Oxfordshire Community Stroke Project (OCSP) classification "LACS." Outcome was analyzed by comparing the proportions of patients classified as "LACS" at baseline or "small vessel (lacunar)" at 7 days who were dead or dependent at 3 months.

RESULTS

The positive predictive value of an OCSP diagnosis of a lacunar stroke was 76% (95% CI: 69% to 81%; sensitivity 64% [95% CI: 58% to 70%]; specificity 96% [95% CI: 95% to 97%]; negative predictive value 93% [95% CI: 92% to 94%]; accuracy 91% [95% CI: 89% to 92%]). The 3-month outcomes of patients classified as either OCSP "LACS" within 6 hours of onset or TOAST "small vessel (lacunar)" at 7 days were not significantly different.

CONCLUSIONS

An OCSP LACS diagnosis made within 6 hours of stroke onset is reasonably predictive of a final diagnosis of "small vessel (lacunar)" disease made using TOAST criteria and has a similar relationship to outcome at 3 months.

Future of neuroprotection for acute stroke: in the aftermath of the SAINT trials

The concept of neuroprotective therapy for acute ischemic stroke to salvage tissue at risk and improve functional outcome is based on sound scientific principles and extensive preclinical animal studies demonstrating efficacy. The failure of most neuroprotective drugs in clinical trials has been due to inadequate preclinical testing and flawed clinical development programs. The Stroke Therapy Academic Industry Roundtable (STAIR) group has outlined rational approaches to preclinical and clinical studies. The positive results from the first Stroke-Acute-Ischaemic-NXY-Treatment (SAINT-I) trial of the free-radical spin-trap drug, NXY-059, which followed many of the STAIR guidelines, reinvigorated enthusiasm in neuroprotection, but the SAINT-II trial did not replicate the positive effect on the same primary prespecified outcome measure. This has led to concerns about the future of neuroprotection as a therapeutic strategy for acute ischemic stroke. We discuss new suggestions to bridge the chasm between preclinical animal modeling and acute human stroke trials to potentially enhance the future assessment of novel neuroprotective drugs.

Intra- and interrater reliability of ischemic lesion volume measurements on diffusion-weighted, mean transit time and fluid-attenuated inversion recovery MRI

BACKGROUND AND PURPOSE

We investigated the intra- and interrater reliability of ischemic lesion volumes measurements assessed by different MRI sequences at various times from onset.

METHODS

Ischemic lesion volumes were measured for intrarater reliability using diffusion-weighted (DWI), mean transit time (MTT) perfusion and fluid-attenuated inversion recovery (FLAIR) MRI at chronic (>3 days from stroke onset) time points. A single intrarater reader, blind to clinical information and time point, repeated the volume measurements on two occasions separated by at least 1 week. Interrater reliability was also obtained in the second set of patients using acute DWI, MTT and chronic FLAIR MRI. Four blinded readers performed these volume measurements. Average deviations across repeat measurements per lesion and differences between sample means between the two measurements were calculated globally, ie, across all sequences and time points, and per reader type for each sequence at each time point.

RESULTS

There was good concordance of the mean sample volumes of the 2 intrarater readings (deviations were <4% and 2 mL globally, <2% and 2 mL for DWI, <6% and 7 mL for MTT, and <2% and 1 mL for FLAIR). There was also good concordance of the interrater readings (<5% and 2 mL globally).

CONCLUSIONS

Repeat measurements of stroke lesion volumes show excellent intra- and interrater concordance for DWI, MTT and FLAIR at acute through chronic time points.