Nimodipine and perfusion changes after stroke

Neuroprotection in Acute Ischemic Stroke: A Battle Against the Biology of Nature

Stroke is the second most common cause of global death following coronary artery disease. Time is crucial in managing stroke to reduce the rapidly progressing insult of the ischemic penumbra and the serious neurologic deficits that might follow it. Strokes are mainly either hemorrhagic or ischemic, with ischemic being the most common of all types of strokes. Thrombolytic therapy with recombinant tissue plasminogen activator and endovascular thrombectomy are the main types of management of acute ischemic stroke (AIS). In addition, there is a vital need for neuroprotection in the setting of AIS. Neuroprotective agents are important to investigate as they may reduce mortality, lessen disability, and improve quality of life after AIS. In our review, we will discuss the main types of management and the different modalities of neuroprotection, their mechanisms of action, and evidence of their effectiveness after ischemic stroke.

Effect of drug interventions on cerebral hemodynamics in ischemic stroke patients

The ischemic penumbra is sensitive to alterations in cerebral perfusion. A myriad of drugs are used in acute ischemic stroke (AIS) management, yet their impact on cerebral hemodynamics is poorly understood. As part of the Cerebral Autoregulation Network led INFOMATAS project (Identifying New Targets for Management and Therapy in Acute Stroke), this paper reviews some of the most common drugs a patient with AIS will come across and their potential influence on cerebral hemodynamics with a particular focus being on cerebral autoregulation (CA). We first discuss how compounds that promote clot lysis and prevent clot formation could potentially impact cerebral hemodynamics, before focusing on how the different classes of antihypertensive drugs can influence cerebral hemodynamics. We discuss the different properties of each drug and their potential impact on cerebral perfusion and CA. With emerging interest in CA status of AIS patients, either during or soon after treatment when timely reperfusion and salvageable tissue is at its most critical, the properties of these pharmacological agents may be relevant for modelling cerebral perfusion accuracy and for setting individualised treatment strategies.

Nitroglycerin Is Not Associated with Improved Cerebral Perfusion in Acute Ischemic Stroke

OBJECTIVE

The study was conducted to test the hypothesis that nitroglycerin (NTG) increases cerebral perfusion focally and globally in acute ischemic stroke patients, using serial perfusion-weighted imaging (PWI) magnetic resonance imaging measurements.

PATIENTS AND METHODS

Thirty-five patients underwent PWI immediately before and 72 h after administration of a transdermal NTG patch or no treatment. Patients with baseline mean arterial pressure (MAP) > 100 mmHg (NTG group, n = 20) were treated with transdermal NTG (0.2 mg/h) for 72 h, without a nitrate-free interval. Patients with MAP ≤ 100 mmHg (untreated group, n = 15) were not treated. The primary outcome measure was absolute cerebral blood flow (CBF) in the hypoperfused region at 72 h.

RESULTS

The mean baseline absolute CBF in the hypoperfused region was similar in the NTG group (33.3 ± 10.2 ml/100 g/min) and untreated (32.7 ± 8.4 ml/100 g/min, p = 0.4) groups. The median (IQR) baseline infarct volume was 10.4 (2.5-49.3) ml in the NTG group and 32.6 (8.6-96.7) ml in the untreated group (p = 0.09). MAP change in the NTG group was 1.2 ± 12.6 and 8 ± 20.7 mmHg at 2 h and 72 h, respectively. Mean absolute CBF in the hypoperfused region at 72 h was similar in the NTG (29.9 ± 12 ml/100 g/min) and untreated groups (24.1 ± 10 ml/100 g/min, p = 0.8). The median infarct volume increased in untreated (11.8 (5.7-44.2) ml) than the NTG group (3.2 (0.5-16.5) ml; p = 0.033) on univariate analysis, however, there was no difference on regression analysis.

CONCLUSION

NTG was not associated with improvement in cerebral perfusion in acute ischemic stroke patients.

Calcium antagonists for acute ischemic stroke

BACKGROUND

The sudden loss of blood supply in ischemic stroke is associated with an increase of calcium ions within neurons. Inhibiting this increase could protect neurons and might reduce neurological impairment, disability, and handicap after stroke.

OBJECTIVES

To assess the effects of calcium antagonists for reducing the risk of death or dependency after acute ischemic stroke. We investigated the influence of different drugs, dosages, routes of administration, time intervals after stroke, and trial design on the outcomes.

SEARCH METHODS

The evidence is current to 6 February 2018. We searched the Cochrane Stroke Group Trials Register (6 February 2018), Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 2), MEDLINE Ovid (1950 to 6 February 2018), Embase Ovid (1980 to 6 February 2018), and four Chinese databases (6 February 2018): Chinese Biological Medicine Database (CBM-disc), China National Knowledge Infrastructure (CNKI), Chinese Scientific Periodical Database of VIP information, and Wanfang Data. We also searched the following trials registers: ClinicalTrials.gov, EU Clinical Trials Register, Stroke Trials Registry, ISRCTN registry, WHO International Clinical Trials Registry Platform, and Chinese Clinical Trial Registry, and we contacted trialists and researchers.

SELECTION CRITERIA

Randomized controlled trials comparing a calcium antagonist versus control in people with acute ischemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, extracted data, assessed risk of bias, and applied the GRADE approach to assess the quality of the evidence. We used death or dependency at the end of long-term follow-up (at least three months) in activities of daily living as the primary outcome. We used standard Cochrane methodological procedures.

MAIN RESULTS

We included 34 trials involving 7731 participants. All the participants were in the acute stage of ischemic stroke, and their age ranged from 18 to 85 years, with the average age ranging from 52.3 to 74.6 years across different trials. There were more men than women in most trials. Twenty-six trials tested nimodipine, and three trials assessed flunarizine. One trial each used isradipine, nicardipine, PY108-608, fasudil, and lifarizine. More than half of these trials followed participants for at least three months. Calcium antagonists showed no effects on the primary outcome (risk ratio (RR) 1.05; 95% confidence interval (CI) 0.98 to 1.13; 22 trials; 22 studies; 6684 participants; moderate-quality evidence) or on death at the end of follow-up (RR 1.07, 95% CI 0.98 to 1.17; 31 trials; 7483 participants; moderate-quality evidence). Thirteen trials reported adverse events, finding no significant differences between groups. Most trials did not report the allocation process or how they managed missing data, so we considered these at high risk of selection and attrition bias. Most trials reported double-blind methods but did not state who was blinded, and none of the trial protocols were available.

AUTHORS' CONCLUSIONS

We found no evidence to support the use of calcium antagonists in people with acute ischemic stroke.

Astrocyte Activation and the Calcineurin/NFAT Pathway in Cerebrovascular Disease

Calcineurin (CN) is a Ca2+/calmodulin-dependent protein phosphatase with high abundance in nervous tissue. Though enriched in neurons, CN can become strongly induced in subsets of activated astrocytes under different pathological conditions where it interacts extensively with the nuclear factor of activated T cells (NFATs). Recent work has shown that regions of small vessel damage are associated with the upregulation of a proteolized, highly active form of CN in nearby astrocytes, suggesting a link between the CN/NFAT pathway and chronic cerebrovascular disease. In this Mini Review article, we discuss CN/NFAT signaling properties in the context of vascular disease and use previous cell type-specific intervention studies in Alzheimer's disease and traumatic brain injury models as a framework to understand how astrocytic CN/NFATs may couple vascular pathology to neurodegeneration and cognitive loss.

Intra-arterial administration of papaverine during mechanical thrombectomy for acute ischemic stroke

BACKGROUND

The use of stent retrievers for mechanical thrombectomy in acute ischemic stroke may induce significant vasospasm, which at the early phases of reperfusion may be crucial for rethrombosis of the recanalized vessel. We aimed to study whether the use of intra-arterial papaverine in selected cases of vasospasm was associated with improved cerebral perfusion, arterial reocclusion, or increased hemorrhagic complications.

METHODS

We retrospectively studied 9 consecutive patients with large artery acute occlusion, treated with stent retriever and intra-arterial papaverine. Onset to administration of intravenous recombinant tissue-plasminogen activator time, baseline National Institute of Health Stroke Scale, time to reperfusion, number of passes of the stent retriever, modified Rankin Scale score at discharge, postprocedural hemorrhage, onset to reperfusion time, papaverine dose, and thrombolysis in cerebral infarction grade were recorded in all patients.

RESULTS

After papaverine administration, the caliber of the infused arteries and their flow was increased in all cases. In none of the treated cases a reocclusion occurred after papaverine infusion. In one of the studied patients (11%), a parenchymal bleeding occurred 36 hours postoperatively.

CONCLUSIONS

This small study suggests that intra-arterial infusion of papaverine for the treatment of cerebral vasospasm after mechanical thrombectomy in acute ischemic stroke is effective and safe.

Interventions for deliberately altering blood pressure in acute stroke

BACKGROUND

It is unclear whether blood pressure should be altered actively during the acute phase of stroke. This is an update of a Cochrane review first published in 1997, and previously updated in 2001 and 2008.

OBJECTIVES

To assess the clinical effectiveness of altering blood pressure in people with acute stroke, and the effect of different vasoactive drugs on blood pressure in acute stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched in February 2014), the Cochrane Database of Systematic reviews (CDSR) and the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 2), MEDLINE (Ovid) (1966 to May 2014), EMBASE (Ovid) (1974 to May 2014), Science Citation Index (ISI, Web of Science, 1981 to May 2014) and the Stroke Trials Registry (searched May 2014).

SELECTION CRITERIA

Randomised controlled trials of interventions that aimed to alter blood pressure compared with control in participants within one week of acute ischaemic or haemorrhagic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, assessed trial quality and extracted data. The review authors cross-checked data and resolved discrepancies by discussion to reach consensus. We obtained published and unpublished data where available.

MAIN RESULTS

We included 26 trials involving 17,011 participants (8497 participants were assigned active therapy and 8514 participants received placebo/control). Not all trials contributed to each outcome. Most data came from trials that had a wide time window for recruitment; four trials gave treatment within six hours and one trial within eight hours. The trials tested alpha-2 adrenergic agonists (A2AA), angiotensin converting enzyme inhibitors (ACEI), angiotensin receptor antagonists (ARA), calcium channel blockers (CCBs), nitric oxide (NO) donors, thiazide-like diuretics, and target-driven blood pressure lowering. One trial tested phenylephrine.At 24 hours after randomisation oral ACEIs reduced systolic blood pressure (SBP, mean difference (MD) -8 mmHg, 95% confidence interval (CI) -17 to 1) and diastolic blood pressure (DBP, MD -3 mmHg, 95% CI -9 to 2), sublingual ACEIs reduced SBP (MD -12.00 mm Hg, 95% CI -26 to 2) and DBP (MD -2, 95%CI -10 to 6), oral ARA reduced SBP (MD -1 mm Hg, 95% CI -3 to 2) and DBP (MD -1 mm Hg, 95% CI -3 to 1), oral beta blockers reduced SBP (MD -14 mm Hg; 95% CI -27 to -1) and DBP (MD -1 mm Hg, 95% CI -9 to 7), intravenous (iv) beta blockers reduced SBP (MD -5 mm Hg, 95% CI -18 to 8) and DBP (-5 mm Hg, 95% CI -13 to 3), oral CCBs reduced SBP (MD -13 mmHg, 95% CI -43 to 17) and DBP (MD -6 mmHg, 95% CI -14 to 2), iv CCBs reduced SBP (MD -32 mmHg, 95% CI -65 to 1) and DBP (MD -13, 95% CI -31 to 6), NO donors reduced SBP (MD -12 mmHg, 95% CI -19 to -5) and DBP (MD -3, 95% CI -4 to -2) while phenylephrine, non-significantly increased SBP (MD 21 mmHg, 95% CI -13 to 55) and DBP (MD 1 mmHg, 95% CI -15 to 16).Blood pressure lowering did not reduce death or dependency either by drug class (OR 0.98, 95% CI 0.92 to 1.05), stroke type (OR 0.98, 95% CI 0.92 to 1.05) or time to treatment (OR 0.98, 95% CI 0.92 to 1.05). Treatment within six hours of stroke appeared effective in reducing death or dependency (OR 0.86, 95% CI 0.76 to 0.99) but not death (OR 0.70, 95% CI 0.38 to 1.26) at the end of the trial. Although death or dependency did not differ between people who continued pre-stroke antihypertensive treatment versus those who stopped it temporarily (worse outcome with continuing treatment, OR 1.06, 95% CI 0.91 to 1.24), disability scores at the end of the trial were worse in participants randomised to continue treatment (Barthel Index, MD -3.2, 95% CI -5.8, -0.6).

AUTHORS' CONCLUSIONS

There is insufficient evidence that lowering blood pressure during the acute phase of stroke improves functional outcome. It is reasonable to withhold blood pressure-lowering drugs until patients are medically and neurologically stable, and have suitable oral or enteral access, after which drugs can than be reintroduced. In people with acute stroke, CCBs, ACEI, ARA, beta blockers and NO donors each lower blood pressure while phenylephrine probably increases blood pressure. Further trials are needed to identify which people are most likely to benefit from early treatment, in particular whether treatment started very early is beneficial.

Intra-arterial vasodilator use during endovascular therapy for acute ischemic stroke might improve reperfusion rate

Treatment of acute ischemic stroke (AIS) is an evolving field. New treatment options are still needed in order to achieve greater success rates for arterial recanalization. Intra-arterial therapy (lAT) is an option for AIS patients who are not good candidates for intravenous (i.v.) recombinant tissue plasminogen activator (rt-PA) or where it has failed. While good data establishing the role of IAT in AIS management are lacking, the potential clinical efficacy of IAT is based on the premise that recanalization and reperfusion may result in better clinical outcome. Although lAT recanalization and reperfusion rates of large vessel occlusion are much higher than they are for i.v. rt-PA, IAT's radiological efficacy is still far from perfect. Vasodilator use during IAT for AIS may increase the recanalization and reperfusion rates of such therapy. In this report, we describe the radiographic and clinical outcomes in a cohort of AIS patients who received intra-arterial (i.a.) vasodilators during IAT and summarize the role of i.a. vasodilators in the process of recanalization and reperfusion.

Calcium antagonists for acute ischemic stroke

BACKGROUND

The sudden loss of blood supply in ischemic stroke is associated with the increase of calcium ions within neurons. Inhibiting this increase could protect neurons and hence might reduce neurological impairment, disability and handicap after stroke.

OBJECTIVES

To determine whether calcium antagonists reduce the risk of death or dependency after acute ischemic stroke. To investigate the influence of different drugs, dosages, routes of administration, time intervals after stroke and trial design on the risk of a primary outcome.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (January 2012), MEDLINE (1950 to December 2011), EMBASE (1980 to December 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2011 issue 4) and four Chinese databases (December 2011): Chinese Biological Medicine Database (CBM-disc), China National Knowledge Infrastructure (CNKI), Chinese scientific periodical database of VIP information and Wanfang Data. We also contacted trialists and researchers.

SELECTION CRITERIA

All truly randomized trials comparing a calcium antagonist with control in patients with acute ischemic stroke.

DATA COLLECTION AND ANALYSIS

Two authors assessed all trials and extracted the data. We used death or dependency at the end of long-term follow-up (at least three months) in activities of daily living as the primary outcome. Analyses were, if possible, intention-to-treat.

MAIN RESULTS

We included 34 trials including 7731 patients. There was no effect of calcium antagonists on the primary outcome (risk ratio (RR) 1.05; 95% confidence interval (CI) 0.98 to 1.13), or on death at the end of follow-up (RR 1.07, 95% CI 0.98 to 1.17). Comparisons of different doses of nimodipine suggested that the highest doses were associated with poorer outcome.

AUTHORS' CONCLUSIONS

No evidence is available using calcium antagonists in patients with acute ischemic stroke is effective.

Vasoactive drugs for acute stroke

BACKGROUND

It is unclear whether blood pressure (BP) should be altered actively during the acute phase of stroke.

OBJECTIVES

To assess the effect of lowering or elevating BP in people with acute stroke, and the effect of different vasoactive drugs on BP in acute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched June 2009), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2009), MEDLINE (1966 to October 2009), EMBASE (1980 to October 2009), and Science Citation Index (1981 to October 2009).

SELECTION CRITERIA

Randomised trials of interventions that would be expected, on pharmacological grounds, to alter BP in patients within one week of the onset of acute stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the trial inclusion criteria, assessed trial quality, and extracted data.

MAIN RESULTS

We identified 131 trials involving in excess of 18,000 patients; a further 13 trials are ongoing. We obtained data for 43 trials (7649 patients). Among BP-lowering trials, beta receptor antagonists lowered BP (early systolic BP (SBP) mean difference (MD) -6.1 mmHg, 95% CI -11.4 to -0.9; late SBP MD -4.9 mmHg, 95% CI -10.2 to 0.4; late diastolic BP (DBP) MD -4.5 mmHg, 95% CI -7.8 to -1.2). Oral calcium channel blockers (CCB) lowered BP (late SBP MD -3.2 mmHg, 95% CI -5.4 to -1.1; early DBP MD -2.5, 95% CI -5.6 to 0.7; late DBP MD -2.1, 95% CI -3.5 to -0.7). Nitric oxide donors lowered BP (early SBP MD -10.3 mmHg, 95% CI -17.6 to -3.0). Prostacyclin lowered BP (late SBP MD, -7.7 mmHg, 95% CI -15.6 to 0.2; late DBP MD -3.9 mmHg, 95% CI -8.1 to 0.4). Among BP-increasing trials, diaspirin cross-linked haemoglobin (DCLHb) increased BP (early SBP MD 15.3 mmHg, 95% CI 4.0 to 26.6; late SBP MD 15.9 mmHg, 95% CI 1.8 to 30.0). None of the drug classes significantly altered outcome apart from DCLHb which increased combined death or dependency (odds ratio (OR) 5.41, 95% CI 1.87 to 15.64).

AUTHORS' CONCLUSIONS

There is not enough evidence to evaluate reliably the effect of altering BP on outcome after acute stroke. However, treatment with DCLHb was associated with poor clinical outcomes. Beta receptor antagonists, CCBs, nitric oxide, and prostacyclin each lowered BP during the acute phase of stroke. In contrast, DCLHb increased BP.

Effect of early treatment with anti-hypertensive drugs on short and long-term mortality in patients with an acute cardiovascular event

BACKGROUND

Acute cardiovascular events represent a therapeutic challenge. Blood pressure lowering drugs are commonly used and recommended in the early phase of these settings. This review analyses randomized controlled trial (RCT) evidence for this approach.

OBJECTIVES

To determine the effect of immediate and short-term administration of anti-hypertensive drugs on all-cause mortality, total non-fatal serious adverse events (SAE) and blood pressure, in patients with an acute cardiovascular event, regardless of blood pressure at the time of enrollment.

SEARCH STRATEGY

MEDLINE, EMBASE, and Cochrane clinical trial register from Jan 1966 to February 2009 were searched. Reference lists of articles were also browsed. In case of missing information from retrieved articles, authors were contacted.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing anti-hypertensive drug with placebo or no treatment administered to patients within 24 hours of the onset of an acute cardiovascular event.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed risk of bias. Fixed effects model with 95% confidence intervals (CI) were used. Sensitivity analyses were also conducted.

MAIN RESULTS

Sixty-five RCTs (N=166,206) were included, evaluating four classes of anti-hypertensive drugs: ACE inhibitors (12 trials), beta-blockers (20), calcium channel blockers (18) and nitrates (18). Acute stroke was studied in 6 trials (all involving CCBs). Acute myocardial infarction was studied in 59 trials. In the latter setting immediate nitrate treatment (within 24 hours) reduced all-cause mortality during the first 2 days (RR 0.81, 95%CI [0.74,0.89], p<0.0001). No further benefit was observed with nitrate therapy beyond this point. ACE inhibitors did not reduce mortality at 2 days (RR 0.91,95%CI [0.82, 1.00]), but did after 10 days (RR 0.93, 95%CI [0.87,0.98] p=0.01). No other blood pressure lowering drug administered as an immediate treatment or short-term treatment produced a statistical significant mortality reduction at 2, 10 or >/=30 days. There was not enough data studying acute stroke, and there were no RCTs evaluating other acute cardiovascular events.

AUTHORS' CONCLUSIONS

Nitrates reduce mortality (4-8 deaths prevented per 1000) at 2 days when administered within 24 hours of symptom onset of an acute myocardial infarction. No mortality benefit was seen when treatment continued beyond 48 hours. Mortality benefit of immediate treatment with ACE inhibitors post MI at 2 days did not reach statistical significance but the effect was significant at 10 days (2-4 deaths prevented per 1000). There is good evidence for lack of a mortality benefit with immediate or short-term treatment with beta-blockers and calcium channel blockers for acute myocardial infarction.

The effects of transdermal glyceryl trinitrate, a nitric oxide donor, on blood pressure, cerebral and cardiac hemodynamics, and plasma nitric oxide levels in acute stroke

High blood pressure in acute stroke is common and appears to be associated with a poor outcome. Lowering blood pressure might therefore improve outcome, provided that cerebral perfusion is not compromised. We assessed the effects of glyceryl trinitrate (GTN) on cerebral and systemic hemodynamic measures in acute stroke. Ninety patients with acute ischemic or hemorrhagic stroke were randomized within 72 hours of ictus to transdermal GTN given daily for 10 days (either 5 mg, 5 mg for 4 days then 10 mg, or 10 mg) or control. Twenty-four hour blood pressure monitoring, middle cerebral artery blood velocity, cardiac output, augmentation index, and plasma nitric oxide levels were each measured at baseline and then on days 1, 4, 5, and 10. The primary outcome was blood pressure on day 1. We found that GTN lowered mean peripheral arterial blood pressure on day 1 by 5.3% to 6.7% in a dose dependent manner as compared with control (mean, SD): control, 108.8 (15.1) mmHg; 5 mg, 102.5 (13.9) mmHg; 5/10 mg, 103.4 (14.9) mmHg; 10 mg, 101.5 (12.6) mmHg; (P = .005). Increasing the dose from 5 to 10 mg on day 5 resulted in an overall reduction in blood pressure of 11.4% as compared with leaving the dose at 5 mg (P = .006). GTN reduced peripheral pulse pressure, central aortic blood pressure, pulse pressure, and augmentation index on day 1. Middle cerebral artery blood velocity and pulsatility index in the affected hemisphere, cardiac output, systemic peripheral resistance, and plasma nitric oxide levels were not altered by GTN. Treatment with GTN was associated with headache: control 0 (0%), GTN 9 (15%) (P = .027); no negative effect on end-of-treatment death or deterioration, or 3 month death or dependency was discernable. GTN reduced peripheral blood pressure in a dose-dependent fashion in patients with acute stroke at day 1 and also reduced central blood pressure and augmentation index. In contrast, GTN did not alter middle cerebral artery blood velocity or pulsatility index in the affected hemispheres, suggesting that cerebral blood flow did not change. A trial assessing the effect of lowering blood pressure with GTN on safety and functional outcome in patients with acute stroke is now warranted.

Voltage-gated cation channel modulators for the treatment of stroke

Neuronal voltage-gated cation channels regulate the transmembrane flux of calcium, sodium and potassium. Neuronal ischaemia occurring during acute ischaemic stroke results in the breakdown in the normal function of these ion channels, contributing to a series of pathological events leading to cell death. A dramatic increase in the intracellular concentration of calcium during neuronal ischaemia plays a particularly important role in the neurotoxic cascade resulting in stroke-related acute neurodegeneration. One approach to provide therapeutic benefit following ischaemic stroke has been to target neuronal voltage-gated cation channels, and particularly blockers of calcium and sodium channels, for post-stroke neuroprotection. A recent development has been the identification of openers of large-conductance calcium- and voltage-dependent potassium channels (maxi-K channels), which hyperpolarize ischaemic neurons, reduce excitatory amino acid release, and reduce ischaemic calcium entry. Thus far, targeting these voltage-gated cation channels has not yet yielded significant clinical benefit. The reasons for this may involve the lack of small-molecule blockers of many neuronal members of these ion channel families and the design of preclinical stroke models, which do not adequately emulate the clinical condition and hence lack sufficient rigor to predict efficacy in human stroke. Furthermore, there may be a need for changes in clinical trial designs to optimise the selection of patients and the course of drug treatment to protect neurons during all periods of potential neuronal sensitivity to neuro-protectants. Clinical trials may also have to be powered to detect small effect sizes or be focused on patients more likely to respond to a particular therapy. The development of future solutions to these problems should result in an improved probability of success for the treatment of stroke.

Blood pressure, nimodipine, and outcome of ischemic stroke

OBJECTIVES

The reduction of blood pressure (BP) caused by nimodipine has been proposed as an explanation for the poor results in ischemic stroke trials. We evaluated further the relationships between BP, nimodipine, and outcome of ischemic stroke, and also searched for other possible explaining mechanisms.

PATIENTS AND METHODS

All 350 participants of an earlier placebo controlled trial on oral nimodipine were included in this study. Among other variables, the admission BP, and the change of BP during the first day were noted. The 3 week and 3 month functional outcome was assessed with a modified Rankin grading.

RESULTS

The severity of stroke was the utmost important predictor of outcome. Visible cerebral infarction on computed tomography (CT) was associated with severe stroke and an early commencement (within 24 h of stroke onset) of nimodipine treatment. In the nimodipine arm, high initial systolic and diastolic BP measured < or =24 h of stroke onset were independent predictors of good functional outcome (Rankin grades 1 and 2), whereas BP change was not. The survivors in the nimodipine arm with mild to moderately severe stroke had higher initial BP than the deceased ones, in severe strokes the situation was the opposite.

CONCLUSIONS

Stroke severity, visible cerebral infarcts on CT, and early commencement of nimodipine treatment were associated. Overall, high initial systolic and diastolic BP predicted a good functional outcome in patients on nimodipine. In severe strokes, the combination of nimodipine and high initial BP was associated with increased risk of death.

[Brain perfusion SPECT in the prognostic assessment of stroke]

PURPOSE

To compare the diagnostic yield of CT scan and perfusion SPECT on admission and its prognostic value in clinical outcome.

METHODS

25 ischemic stroke cases were studied on admission (<24 h) and at 30-60 days by CT scan, 99mTc-HMPAO-SPECT and neurological scales. Infarct size and severity on SPECT were assessed: visually "Total Weighted Score," added value in 22 areas, and by several semiquantitative count-based indices.

RESULTS

Sensitivity: the first CT scan was positive in 24% patients, initial SPECT in 75% (73% of pure subcortical infarcts and 91% of those with cortical involvement). Localization: kappa: 0.725 between SPECT findings on admission and those in control-CT at 5 days. Extent and severity: correlations between count-based and visual indices (r: >0.719), the latter correlated slightly better with clinical scales. Both predicted similarly (Rho>0.739) infarct size in CT diagnostic scan. Early Outcome: There were statistical differences between deceased and survivors in SPECT (<24h) indices and CT-infarct size (mean 5 days), but not in neurological scores on admission. Long term Outcome: Correlation of initial SPECT indices with follow-up functional scores (SNSLP, Barthel index; mean 37 days) was only significant for visual SPECT indices (Rho:0.560 to 0.620). Nevertheless the best predictor of functional status on discharge was the Barthel Index on admission.

CONCLUSIONS

1) Early SPECT has good sensitivity and accurate infarct size prediction so it can be a useful tool for deciding thrombolytic therapy; 2) Visual scores perform as well as more complex indices; 3) Infarct volume seems to be a critical determinant in vital outcome; other factors (strategic localization, etc.) might influence long term functional status.

Protective effect of nimodipine on behavior and white matter of rats with hydrocephalus

OBJECT

Hydrocephalus, a pathological dilation of the ventricles of the brain, causes damage to periventricular white matter, at least in part, through chronic ischemia. The authors tested the hypothesis that treatment with nimodipine, an L-type calcium channel-blocking agent with demonstrated efficacy in a range of cerebral ischemic disorders, would ameliorate the adverse effects of experimental hydrocephalus.

METHODS

Hydrocephalus was induced in 3-week-old rats by injection of kaolin into the cisterna magna. The rats were treated by continuous administration of nimodipine or control vehicle for 2 weeks, beginning 2 weeks after induction of hydrocephalus. During the treatment period, the animals underwent repeated tests of motor and cognitive behavior. At the end of the treatment period, the rat brains were analyzed by histopathological and biochemical means. Nimodipine treatment prevented the declines in motor and cognitive behavior that were observed in untreated control rats. During the treatment period, ventricular enlargement, determined by magnetic resonance imaging, was equal in the two groups, although the corpus callosum was thicker in the treated rats. Myelin content in white matter and synaptophysin content in gray matter, an indicator of synapses, did not differ.

CONCLUSIONS

The protective effect of nimodipine is most likely based on improved blood flow, although prevention of calcium influx-mediated proteolytic processes in axons cannot be excluded. Adjunctive pharmacological therapy may be beneficial to patients with hydrocephalus.

Acute protective effect of nimodipine and dimethyl sulfoxide against hypoxic and ischemic damage in brain slices

Nimodipine and dimethyl sulfoxide (DMSO) were tested (alone and in combination) regarding their ability to increase hypoxic tolerance of brain slices under 'hypoxic' (deprivation of oxygen) or 'ischemic' (hypoxia+withdrawal of glucose) conditions. Direct current (DC) and evoked potentials were recorded in the CA1 region of hippocampal slices of adult guinea pigs. After induction of hypoxia or ischemia, the latency of anoxic terminal negativity (ATN) of the DC potential was determined during superfusion with artificial cerebrospinal fluid alone (aCSF), and during superfusion with aCSF containing DMSO [0.1% (14.1 mmol/l) and 0.4% (56.3 mmol/l)] with the addition of nimodipine (40 micromol/l). Latencies of ATN with first hypoxia were 6.7+/-3.7 min in the control group, 9. 3+/-4.2 min in the 0.4% DMSO group and 12.3+/-5.5 min (P=0.007) in the nimodipine/0.4% DMSO group. Latencies of ATN with first ischemia were 2.9+/-2 min in the control group, 4.1+/-1.6 min in the 0.1% DMSO group, 7.1+/-3.9 min in the 0.4% DMSO group (P=0.006), 5.3+/-1. 5 min in the nimodipine/0.1% DMSO group and 7.6+/-3 min (P<0.001) in the nimodipine/0.4% DMSO group. DMSO (0.4%), either alone or in combination with nimodipine, increase the latency of the ATN after acute onset of hypoxia and ischemia.

The future of stroke treatment

The concept of the therapeutic window of opportunity in ischemic neuronal injury and understanding the necessity of well organized stroke services revolutionized the management of acute ischemic stroke during the last years of the second millennium. Thrombolysis with IV rt-PA within 3 hours from the onset of symptoms is an established therapy for selected patients. The challenge of stroke therapy at the outset of this millennium is how to translate basic pathophysiologic evidence of ischemic neuronal injury into novel neuroprotective therapies either independently or combined with thrombolysis. Great hopes are placed in identification of pivotal molecular events in ischemic brain tissue and design of effective pharmacological interventions to target them. Aggressive, invasive procedures are also being developed and therapies such as intra-arterial clot lysis, hemicraniectomy and mild hypothermia may improve the bleakest outcomes associated with the most severe forms of ischemic stroke, but their role must be rigorously evaluated. There is, however, no need to wait for future breakthroughs. The existing evidence strongly implies that good care of patients with stroke starts with organization of the entire stroke chain; from the prehospital scene, through the emergency room, to the stroke unit. Without structured stroke services no pharmacological or intervening therapy is likely to improve the outcome of the patient with a stroke.

Calcium antagonists for acute ischemic stroke

BACKGROUND

The sudden loss of blood supply in ischemic stroke is associated with increased levels of calcium ions within neurones. Inhibiting this increase could protect neurones and is thought to reduce neurological impairment, disability and handicap after stroke.

OBJECTIVES

The aim of this review is to determine whether calcium antagonists reduce the risk of death or dependency after acute ischemic stroke. The influence of different drugs, dosages, routes of administration, time intervals after stroke and trial design on the risk of poor outcome was investigated.

SEARCH STRATEGY

Relevant trials were identified in the Specialised Register of Controlled Trials (last searched: March 1999).

SELECTION CRITERIA

All truly randomised trials comparing a calcium antagonist with control in patients with acute ischaemic stroke were included.

DATA COLLECTION AND ANALYSIS

Two authors assessed all trials and extracted the data. Poor outcome, defined as death or dependency in activities of daily living, was used as the main outcome. Analyses were, if possible, "intention-to-treat".

MAIN RESULTS

46 trials were identified of which 28 were included (7521 patients). No effect of calcium antagonists on poor outcome at the end of follow-up (OR 1.07, 95% CI 0.97/1.18), or on death at end of follow-up (OR 1.10, 95% CI 0.98/1.24) was found. Intravenous administration (i.v.) of calcium antagonists was associated with an increase in the number of patients with poor outcome compared to oral administration (indirect comparisons). Comparisons of different doses of nimodipine suggested that the highest doses were associated with poorer outcome. Administration within 12 hours of onset was associated with an increase in the proportion of patients with poor outcome, but this effect was largely due to the poor results associated with i.v. administration. A subgroup analysis on nimodipine (oral, 120 mg/day) started within 12 hours of stroke onset, did not show a beneficial effect.

REVIEWER'S CONCLUSIONS

No evidence is available to justify the use of calcium antagonists in patients with acute ischaemic stroke.