Clazosentan to overcome neurological ischemia and infarction occurring after subarachnoid hemorrhage (CONSCIOUS-1): randomized, double-blind, placebo-controlled phase 2 dose-finding trial

Lower incidence of cerebral infarction correlates with improved functional outcome after aneurysmal subarachnoid hemorrhage

Despite an undisputed association between vasospasm and delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (SAH), there is debate if this association implies causality. It has been suggested that cerebral infarction is a better outcome measure than vasospasm in clinical trials and observational studies. To further investigate the relationship between infarction and outcome, we performed a systematic review and meta-analysis of all randomized, double-blind, placebo-controlled trials that studied the efficacy of pharmaceutical preventive strategies in SAH patients, and had both cerebral infarction and clinical outcome as outcome events. Effect sizes were expressed in (pooled) risk ratio (RR) estimates with corresponding 95% confidence intervals (CIs). Sensitivity analyses were performed for studies with a low risk of bias and for those who reported outcome at 3 months after SAH. Twenty-four studies including 8,552 patients were included. Pharmaceutical treatments decreased the incidence of both cerebral infarction (RR: 0.83; 95% CI: 0.74 to 0.93) and of poor functional outcome (RR: 0.92; 95% CI: 0.86 to 0.98). The sensitivity analyses did not change the results essentially. These data suggest that the previously observed association between cerebral infarction and functional outcome implies causality, and that cerebral infarction is a better outcome measure than vasospasm in clinical trials and observational studies.

Gain-of-function polymorphisms of cystathionine β-synthase and delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage

Object

Cystathionine β-synthase (CBS) is an enzyme that metabolizes homocysteine to form H2S in the brain. Hydrogen sulfide functions as a vasodilator as well as a regulator of neuronal ion channels and multiple intracellular signaling pathways. Given the myriad effects of H2S, the authors hypothesized that patients possessing gain-of-function polymorphisms of the CBS gene will experience a decreased incidence of delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH).

Methods

Patients were enrolled in a prospective observational database of aSAH outcomes. DNA was extracted from buccal swabs and sequenced for 3 functional polymorphisms of the CBS gene (699C→T, 844ins68, and 1080C→T) by polymerase chain reaction. Serum homocysteine levels (μmol/L) were assayed. Multivariate analysis was used to determine the relationship between CBS genotype and occurrence of both angiographic vasospasm and DCI.

Results

There were 87 patients included in the study. None of the polymorphisms investigated were significantly associated with the incidence of angiographic vasospasm. However, after controlling for admission hypertension, patients with the gain-of-function 844 WT/ins genotypes were less likely to experience DCI relative to those with the 844 WT/WT genotype (86 patients, p = 0.050), while the decrease-in-function genotype 1080 TT was more likely to experience DCI relative to those with 1080 CC and CT genotypes (84 patients, p = 0.042). Serum homocysteine levels did not correlate with the extent of either angiographic vasospasm or DCI in this analysis.

Conclusions

Polymorphisms of the CBS gene that impart gain-of-function may be associated with a reduced risk of DCI after aSAH, independent of serum homocysteine. Signaling through H2S may mediate protection from DCI following aSAH through a mechanism that does not involve macrovascular vasodilation.

Effect of pharmaceutical treatment on vasospasm, delayed cerebral ischemia, and clinical outcome in patients with aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

As it is often assumed that delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is caused by vasospasm, clinical trials often focus on prevention of vasospasm with the aim to improve clinical outcome. However, the role of vasospasm in the pathogenesis of DCI and clinical outcome is possibly smaller than previously assumed. We performed a systematic review and meta-analysis on all randomized, double-blind, placebo-controlled trials that studied the effect of pharmaceutical preventive strategies on vasospasm, DCI, and clinical outcome in SAH patients to further investigate the relationship between vasospasm and clinical outcome. Effect sizes were expressed in pooled risk ratio (RR) estimates with corresponding 95% confidence intervals (CI). A total of 14 studies randomizing 4,235 patients were included. Despite a reduction of vasospasm (RR 0.80 (95% CI 0.70 to 0.92)), no statistically significant effect on poor outcome was observed (RR 0.93 (95% CI 0.85 to 1.03)). The variety of DCI definitions did not justify pooling the DCI data. We conclude that pharmaceutical treatments have significantly decreased the incidence of vasospasm, but not of poor clinical outcome. This dissociation between vasospasm and clinical outcome could result from methodological problems, sample size, insensitivity of clinical outcome measures, or from mechanisms other than vasospasm that also contribute to poor outcome.

Cerebrospinal fluid 20-HETE is associated with delayed cerebral ischemia and poor outcomes after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Delayed cerebral ischemia (DCI) is a major complication after aneurysmal subarachnoid hemorrhage (aSAH); it is manifested by changes in cerebral blood flow accompanied by neurological decline, and it results in long-term functional and neuropsychological impairment. Preclinical evidence has demonstrated that the arachidonic acid metabolite, 20-hydroxyeicosatetraenoic acid (20-HETE), affects cerebral microvascular tone and cerebral blood flow after aSAH. The purpose of this study was to determine whether cerebrospinal fluid 20-HETE levels were associated with DCI and long-term neuropsychological outcomes in aSAH patients.

METHODS

Cerebrospinal fluid samples were collected twice daily through 14 days after hemorrhage on 108 acute, adult, aSAH patients. Samples were analyzed for 20-HETE via HPLC MSQ single quadrupole mass spectrometry. DCI was defined as the presence of impaired cerebral blood flow (angiographic vasospasm, elevated transcranial Dopplers, abnormal computed tomography or magnetic resonance perfusion scans) accompanied by neurological deterioration. Outcomes, including death and neuropsychological testing, were completed at 3 months after hemorrhage.

RESULTS

Detectable 20-HETE levels were observed in 31% of patient samples and were associated with severity of hemorrhage (Hunt & Hess [HH], P=0.04; Fisher, P=0.05). Detection of 20-HETE was not associated with angiographic vasospasm (P=0.34); however, detectable 20-HETE was significantly associated with DCI (P=0.016). Our data also suggest that detectable 20-HETE was associated with decreased performance in 5 neuropsychological domains.

CONCLUSIONS

These results provide the first clinical evidence that cerebrospinal fluid 20-HETE concentrations are associated with DCI and poor outcomes, and this provides impetus for future studies to elucidate the clinical utility of inhibiting 20-HETE formation as a novel therapeutic intervention in patients with aSAH.

Pharmacological treatment of delayed cerebral ischemia and vasospasm in subarachnoid hemorrhage

Subarachnoid hemorrhage after the rupture of a cerebral aneurysm is the cause of 6% to 8% of all cerebrovascular accidents involving 10 of 100,000 people each year. Despite effective treatment of the aneurysm, delayed cerebral ischemia (DCI) is observed in 30% of patients, with a peak on the tenth day, resulting in significant infirmity and mortality. Cerebral vasospasm occurs in more than half of all patients and is recognized as the main cause of delayed cerebral ischemia after subarachnoid hemorrhage. Its treatment comprises hemodynamic management and endovascular procedures. To date, the only drug shown to be efficacious on both the incidence of vasospasm and poor outcome is nimodipine. Given its modest effects, new pharmacological treatments are being developed to prevent and treat DCI. We review the different drugs currently being tested.

Report of selective cortical infarcts in the primate clot model of vasospasm after subarachnoid hemorrhage

BACKGROUND

In human autopsy studies, 70% to 80% of patients with aneurysmal subarachnoid hemorrhage (SAH) showed infarcts in cerebral cortex covered by subarachnoid blood. Thus far, no animal model of SAH is known to produce this peculiar infarct pattern, and its pathogenesis remains enigmatic.

OBJECTIVE

To investigate whether such infarcts occur in the clot model of SAH in primates.

METHODS

We performed a retrospective pathological review of 16 primate brains. In 13 cynomolgus monkeys, a blood clot was placed around the middle cerebral artery after additional removal of the arachnoid membrane from the basal surface of the frontal and temporal cortexes. Three animals underwent sham surgery without placement of a blood clot (controls). The brains were harvested between days 1 and 28 after SAH and examined by a neuropathologist blinded to study group.

RESULTS

We identified 2 types of cortical infarcts. A band of selective cortical laminar necrosis parallel to the cortical surface ("horizontal") was found in 5 animals. The second category of cortical lesions had a "vertical" extension. It included wedge-shaped (n = 2) or pillarlike (n = 2) necrosis. Both horizontal and vertical infarcts were located exclusively in areas adjacent to subarachnoid blood. The presence of a cortical infarct did not correlate with the degree of middle cerebral artery vasospasm (r2 = .24, P = .13).

CONCLUSION

The presence of cortical infarcts suggests that a modified nonhuman primate model of SAH is suitable to examine the pathogenesis of proximal vasospasm and permits investigation of cortical lesions similar to those reported in patients after SAH. Furthermore, it indicates that direct effects of the blood clot on the brain and microcirculation contribute to the development of cortical infarcts after SAH.

Dissociation of Vasospasm and Secondary Effects of Experimental Subarachnoid Hemorrhage by Clazosentan

Background and Purpose—

Endothelin receptor antagonists such as clazosentan decrease large-artery vasospasm after experimental and clinical subarachnoid hemorrhage. We used clazosentan to gain insight into the pathophysiology of subarachnoid hemorrhage by determining if decreasing vasospasm is associated with alleviation of other secondary complications of subarachnoid hemorrhage such as oxidative stress, endothelial nitric oxide synthase dysfunction, microthromboembolism, and neuronal injury.

Methods—

Mice were subjected to subarachnoid hemorrhage by injection of blood into the chiasmatic cistern. They were treated with clazosentan or vehicle by continuous intraperitoneal infusion for 48 hours. Middle cerebral artery vasospasm, superoxide anion radical, peroxynitrite, microthromboemboli, endothelial nitric oxide synthase uncoupling, cerebral blood flow, neuronal injury, and mortality were assessed.

Results—

Clazosentan preserved cerebral blood flow, alleviated vasospasm, and decreased mortality but did not affect superoxide anion radical, peroxynitrite, or microthromboemboli in the brain. Endothelial nitric oxide synthase uncoupling and neuronal injury also were not reduced by clazosentan.

Conclusions—

This study shows large-artery vasospasm is pathophysiologically independent of some other effects of subarachnoid hemorrhage. The findings have implications for development of treatments for this disease.

Detection of Cerebral Compromise With Multimodality Monitoring in Patients With Subarachnoid Hemorrhage

BACKGROUND:

Studies in traumatic brain injury suggest that monitoring techniques such as brain tissue oxygen (Pbto2) and cerebral microdialysis may complement conventional intracranial pressure (ICP) and cerebral perfusion pressure (CPP) measurements.

OBJECTIVE:

In this study of poor-grade (Hunt and Hess grade IV and V) subarachnoid hemorrhage (SAH) patients, we examined the prevalence of brain hypoxia and brain energy dysfunction in the presence of normal and abnormal ICP and CPP.

METHODS:

SAH patients who underwent multimodal neuromonitoring and cerebral microdialysis were studied. We examined the frequency of brain hypoxia and energy dysfunction in different ICP and CPP ranges and the relationship between Pbto2 and the lactate/pyruvate ratio (LPR).

RESULTS:

A total of 2394 samples from 19 patients were analyzed. There were 149 samples with severe brain hypoxia (Pbto2 ≤10 mm Hg) and 347 samples with brain energy dysfunction (LPR >40). The sensitivities of abnormal ICP or CPP for elevated LPR and reduced Pbto2 were poor (21.2% at best), and the LPR or Pbto2 was abnormal in many instances when ICP or CPP was normal. Severe brain hypoxia was often associated with an LPR greater than 40 (86% of samples). In contrast, mild brain hypoxia (≤20 mm Hg) and severe brain hypoxia were observed in only 53% and 36% of samples with brain energy dysfunction, respectively.

CONCLUSION:

Our data demonstrate that ICP and CPP monitoring may not always detect episodes of cerebral compromise in SAH patients. Our data suggest that several complementary monitors may be needed to optimize the care of poor-grade SAH patients.

Unfractionated heparin: multitargeted therapy for delayed neurological deficits induced by subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is associated with numerous "delayed neurological deficits" (DNDs) that have been attributed to multiple pathophysiological mechanisms, including ischemia, microthrombosis, free radical damage, inflammation, and vascular remodeling. To date, effective prophylactic therapy for SAH-induced DNDs has been elusive, due perhaps to the multiplicity of mechanisms involved that render typical, single-agent therapy seemingly futile. We hypothesized that heparin, which has multiple underappreciated salutary effects, might be useful as a multitargeted prophylactic agent against SAH-induced DNDs. We performed a comprehensive review of the literature to evaluate the potential utility of heparin in targeting the multiple pathophysiological mechanisms that have been identified as contributing to SAH-induced DNDs. Our literature review revealed that unfractionated heparin can potentially antagonize essentially all of the pathophysiological mechanisms known to be activated following SAH. Heparin binds >100 proteins, including plasma proteins, proteins released from platelets, cytokines, and chemokines. Also, heparin complexes with oxyhemoglobin, blocks the activity of free radicals including reactive oxygen species, antagonizes endothelin-mediated vasoconstriction, smooth muscle depolarization, and inflammatory, growth and fibrogenic responses. Our review suggests that the use of prophylactic heparin following SAH may warrant formal study.

Preventing vasospasm improves outcome after aneurysmal subarachnoid hemorrhage: rationale and design of CONSCIOUS-2 and CONSCIOUS-3 trials

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) is a frequent but unpredictable complication associated with poor outcome. Current vasospasm therapies are suboptimal; new therapies are needed. Clazosentan, an endothelin receptor antagonist, has shown promise in phase 2 studies, and two randomized, double-blind, placebo-controlled phase 3 trials (CONSCIOUS-2 and CONSCIOUS-3) are underway to further investigate its impact on vasospasm-related outcome after aSAH. Here, we describe the design of these studies, which was challenging with respect to defining endpoints and standardizing endpoint interpretation and patient care. Main inclusion criteria are: age 18-75 years; SAH due to ruptured saccular aneurysm secured by surgical clipping (CONSCIOUS-2) or endovascular coiling (CONSCIOUS-3); substantial subarachnoid clot; and World Federation of Neurosurgical Societies grades I-IV prior to aneurysm-securing procedure. In CONSCIOUS-2, patients are randomized 2:1 to clazosentan (5 mg/h) or placebo. In CONSCIOUS-3, patients are randomized 1:1:1 to clazosentan 5, 15 mg/h, or placebo. Treatment is initiated within 56 h of aSAH and continued until 14 days after aSAH. Primary endpoint is a composite of mortality and vasospasm-related morbidity within 6 weeks of aSAH (all-cause mortality, vasospasm-related new cerebral infarction, vasospasm-related delayed ischemic neurological deficit, neurological signs or symptoms in the presence of angiographic vasospasm leading to rescue therapy initiation). Main secondary endpoint is extended Glasgow Outcome Scale at week 12. A critical events committee assesses all data centrally to ensure consistency in interpretation, and patient management guidelines are used to standardize care. Results are expected at the end of 2010 and 2011 for CONSCIOUS-2 and CONSCIOUS-3, respectively.

Remote ischemic limb preconditioning after subarachnoid hemorrhage: a phase Ib study of safety and feasibility

BACKGROUND AND PURPOSE

Making a limb transiently ischemic has been shown to induce ischemic tolerance in a distant organ. This phenomenon is known as remote ischemic limb preconditioning. We conducted a Phase IB study of remote ischemic limb preconditioning to determine the safety and feasibility of increasing durations of limb ischemia in patients with subarachnoid hemorrhage.

METHODS

Patients with aneurysmal subarachnoid hemorrhage underwent limb preconditioning every 24 to 48 hours for 14 days. Limb preconditioning consisted of 3 5-minute inflations of a blood pressure cuff to 200 mm Hg around a limb followed by 5 minutes of reperfusion. In the lead-in phase, we preconditioned the upper extremities, but this proved impractical and we began preconditioning the leg in a similar manner. Ischemia times were then escalated to 7.5 and 10 minutes. After each session, a visual analog scale was obtained and the extremity examined for neurovascular complications.

RESULTS

A total of 33 patients completed the study. Mean age was 53±12 years and mean Hunt Hess score was 2.4±0.9. In the lead-in phase, an average of 7.7±2.4 preconditioning sessions was completed with mean visual analog scale 3.6±3.4. In the dose escalation phase, an average of 8.6±2.1 preconditioning sessions was done with mean visual analog scale 1.8±2.2 and 2.5±2.9 for the 7.5- and 10-minute cohorts, respectively. No session was prematurely terminated due to subject discomfort. No objective signs of neurovascular injury were observed.

CONCLUSIONS

We found limb preconditioning to be safe and well tolerated, even at ischemia times of 10 minutes, in critically ill patients with subarachnoid hemorrhage.

Monitoring of the inflammatory response after aneurysmal subarachnoid haemorrhage in the clinical setting: review of literature and report of preliminary clinical experience

BACKGROUND

Clinical and experimental studies showed a marked inflammatory response in aneurysmal subarachnoid haemorrhage (SAH), and it has been proposed to play a key role in the development of cerebral vasospasm (CVS). Inflammatory response and occurrence of CVS may represent a common pathogenic pathway allowing point of care diagnostics of CVS. Therefore, monitoring of the inflammatory response might be useful in the daily clinical setting of an ICU. The aim of the current report is to give a summary about factors contributing to the complex pathophysiology of inflammatory response in SAH and to discuss possible monitoring modalities.

METHODS

Review and analysis of the existing literature and definition of own study protocols.

RESULTS

In cerebrospinal fluid, interleukin (IL)-6 has been found to be significantly higher in patients with CVS during the peri-vasospasm period. While systemic inflammatory response syndrome, high C-reactive protein levels and leukocyte counts has been linked with the occurrence of CVS, less has been reported about cytokines levels in the jugular bulb of the internal jugular vein and in the peripheral blood. Preliminary evaluation of own data suggests, that IL-6 values in the peripheral blood and the arterio-jugular differences of IL-6 are increased with the inflammatory response after SAH.

CONCLUSION

Monitoring of the inflammatory response, in particular IL-6, might be a useful tool for the daily clinical management of patients with SAH and CVS.

Influence of different degrees of liver impairment on the pharmacokinetics of clazosentan

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Clazosentan is a selective endothelin A receptor antagonist, formulated for parenteral use, which is in clinical development for the treatment of aneurysmal subarachnoid haemorrhage. The human ADME study showed that most of clazosentan is excreted via the biliary route. The pharmacokinetics (PK) of clazosentan are similar in healthy subjects and those with severe renal impairment.

WHAT THIS STUDY ADDS

The results of the present study showed that there was an increase in the exposure to clazosentan with increasing severity of liver impairment. Changes in PK in subjects with mild liver impairment compared with healthy subjects are unlikely to be clinically relevant. There are significant differences in the PK parameters of clazosentan in subjects with moderate and severe liver impairment compared with healthy subjects. The results of this study will allow confident dosing of clazosentan in individuals with moderate and severe liver impairment. AIM To investigate the effect of mild, moderate and severe liver impairment on the pharmacokinetics (PK), tolerability and safety of clazosentan, an intravenous endothelin receptor antagonist.

METHODS

Healthy subjects with normal liver function (n= 8), subjects with mild (Child Pugh A, n= 8), and with moderate (Child-Pugh B, n= 8) liver impairment received a continuous intravenous infusion of 1 mg h(-1) and subjects with severe liver impairment (Child Pugh C, n= 8) received a continuous intravenous infusion of 0.5 mg h(-1) clazosentan for a duration of 6 h. The pharmacokinetic (PK) parameters of clazosentan were determined by both model-independent and model-dependent methods.

RESULTS

Mean plasma concentrations of clazosentan increased with increasing severity of liver impairment. Geometric means of area under the plasma concentration-time curve from 0 to infinity (AUC((0,∞)) ) were 1.41- (90% CI 1.04, 1.90), 2.37- (90% CI 1.75, 3.19), and 3.79- (90% CI 2.81, 5.11) fold higher in subjects with mild, moderate and severe liver impairment, respectively, compared with healthy subjects. Similar results were obtained by non-compartmental and two-compartmental analysis. A significant positive correlation between clazosentan AUC((0,∞)) and Child-Pugh score (r= 0.83), bilirubin (r= 0.78) and prothrombin time (r= 0.62), and a significant negative correlation with albumin concentrationl (r= 0.71) was observed. Administration of clazosentan was well tolerated in all groups.

CONCLUSIONS

The increase in exposure to clazosentan in Child-Pugh A patients is not expected to be clinically relevant and no dose adjustment for these patients is proposed. It is recommended to reduce the dose of clazosentan to half in Child-Pugh B and to one fourth in Child-Pugh C patients.

Clazosentan: prevention of cerebral vasospasm and the potential to overcome infarction

Cerebral vasospasm is a common complication occurring after aneurysmal subarachnoid hemorrhage (SAH). It is recognized as a leading preventable cause of morbidity and mortality in this patient group, but its management is challenging, and new treatments are needed. Clazosentan is an endothelin receptor antagonist designed to prevent endothelin-mediated cerebral vasospasm. Vajkoczy et al. (Neurosurg 103:9-17, 2005) initially demonstrated that clazosentan reduced moderate/severe angiographically proven vasospasm by 55% relative to placebo. These findings led to the initiation of the CONSCIOUS trial program to further examine the efficacy and safety of clazosentan in reducing angiographic vasospasm and improving clinical outcome after aneurysmal SAH. In the first of these studies, CONSCIOUS-1, 413 patients were randomized to placebo or clazosentan 1, 5 or 15 mg/h. Clazosentan reduced angiographic vasospasm dose-dependently relative to placebo with a maximum risk reduction of 65% with the highest dose. Despite this, there was no benefit of clazosentan on the secondary protocol-defined morbidity/mortality endpoint; however, additional post-hoc and modified endpoint analyses provided some evidence for a potential clinical benefit. Two additional large-scale studies (CONSCIOUS-2 and CONSCIOUS-3) are now underway to further investigate the potential of clazosentan to improve long-term clinical outcome.

Endothelin-1(1-31) induces spreading depolarization in rats

BACKGROUND

The vasoconstrictor endothelin-1(1-21) (ET-1) seems to induce cerebral vasospasm after aneurismal subarachnoid hemorrhage (aSAH). Moreover, ET-1 causes spreading depolarization (SD) via vasoconstriction/ischemia. ET-1(1-31) is an alternate metabolic intermediate in the generation of ET-1. Our aim was to investigate whether endothelin-1(1-31) causes SD in a similar fashion to ET-1.

METHOD

Increasing concentrations of either ET-1, ET-1(1-31) or vehicle were brain topically applied in 29 rats. Each concentration was superfused for one hour while regional cerebral blood flow (rCBF) and direct current electrocorticogram (DC-ECoG) were recorded.

FINDINGS

In response to the highest concentration of 10(-6) M, all animals of both ET groups developed typical SD. At concentrations below 10(-6) M only ET-1 induced SD (n=14 of 19 rats). Thus, the efficacy of ET-1(1-31) to induce SD was significantly lower (P<0.001, two-tailed Fisher's Exact Test).

CONCLUSIONS

Our findings suggest that ET-1(1-31) less potently induces SD compared to ET-1 which implicates that it is a less potent vasoconstrictor. Speculatively, it could be interesting to shift the metabolic pathway towards the alternate intermediate ET-1(1-31) after aSAH as an alternative strategy to ETA receptor inhibition. This could decrease ET-induced vasoconstriction and SD generation while a potentially beneficial basal ETA receptor activation is maintained.

Angiographic vasospasm is strongly correlated with cerebral infarction after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The long-standing concept that delayed cerebral infarction after aneurysmal subarachnoid hemorrhage results exclusively from large artery vasospasm recently has been challenged. We used data from the CONSCIOUS-1 trial to determine the relationship between angiographic vasospasm and cerebral infarction after subarachnoid hemorrhage.

METHODS

We performed a post hoc exploratory analysis of the CONSCIOUS-1 data. All patients underwent catheter angiography before treatment and 9±2 days after subarachnoid hemorrhage. CT was performed before and after aneurysm treatment, and 6 weeks after subarachnoid hemorrhage. Angiograms and CT scans were assessed by centralized blinded review. Angiographic vasospasm was classified as none/mild (0%-33% decrease in arterial diameter), moderate (34%-66%), or severe (≥67%). Infarctions were categorized as secondary to angiographic vasospasm, other, or unknown causes. Logistic regression was conducted to determine factors associated with infarction.

RESULTS

Complete data were available for 381 of 413 patients (92%). Angiographic vasospasm was none/mild in 209 (55%) patients, moderate in 118 (31%), and severe in 54 (14%). Infarcts developed in 6 (3%) of 209 with no/mild, 12 (10%) of 118 patients with moderate, and 25 (46%) of 54 patients with severe vasospasm. Multivariate analysis found a strong association between angiographic vasospasm and cerebral infarction (OR, 9.3; 95% CI, 3.7-23.4). The significant association persisted after adjusting for admission neurological grade and aneurysm size. Method of aneurysm treatment was not associated with a significant difference in frequency of infarction.

CONCLUSIONS

A strong association exists between angiographic vasospasm and cerebral infarction. Efforts directed at further reducing angiographic vasospasm are warranted.

Cerebral infarction after subarachnoid hemorrhage contributes to poor outcome by vasospasm-dependent and -independent effects

BACKGROUND AND PURPOSE

The pathogenesis of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage remains incompletely understood. It is generally assumed that it is caused by angiographic vasospasm. Our aim was to clarify the relationship among angiographic vasospasm, neurological worsening, cerebral infarction, and poor outcome and to investigate whether cerebral infarction also contributes to poor outcome by vasospasm-independent effects.

METHODS

This exploratory analysis used data from 413 patients included in the Clazosentan to Overcome Neurological Ischemia and Infarction Occurring After Subarachnoid Hemorrhage (CONSCIOUS-1) trial. We studied the incidence of neurological worsening, cerebral infarction, and poor outcome in patients with and without angiographic vasospasm. Path analysis implemented by structural equation modeling was performed to determine direct and indirect path coefficients.

RESULTS

Of the 194 patients with moderate to severe vasospasm, 43% had neurological worsening of any cause, 20% had cerebral infarction, and 46% poor outcome. Path coefficients for direct effects on poor outcome were 0.20 for World Federation of Neurological Surgeons Grade 4 to 5, 0.13 for history of hypertension, 0.19 for angiographic vasospasm, 0.16 for neurological worsening, and 0.11 for new cerebral infarction. Cerebral infarction contributed to poor outcome by vasospasm-dependent and -independent effects.

CONCLUSIONS

Our data show that the majority of patients with moderate to severe angiographic vasospasm did not have neurological worsening of any cause or cerebral infarction. Besides, cerebral infarction also has a direct effect on outcome independent of angiographic vasospasm. This suggests that other coexisting factors might be involved in the pathogenesis of delayed cerebral ischemia, which should also be an important research target to improve outcome after subarachnoid hemorrhage.

Impact of systemic inflammatory response syndrome on vasospasm, cerebral infarction, and outcome after subarachnoid hemorrhage: exploratory analysis of CONSCIOUS-1 database

BACKGROUND

Systemic inflammatory response syndrome (SIRS) may develop after aneurysmal subarachnoid hemorrhage (SAH). We investigated factors associated with SIRS after SAH, whether SIRS was associated with complications of SAH such as vasospasm, cerebral infarction, and clinical outcome, and whether SIRS could contribute to a difference in outcome between patients treated by endovascular coiling or neurosurgical clipping of the ruptured aneurysm.

METHODS

This was exploratory analysis of 413 patients in the CONSCIOUS-1 study. SIRS was diagnosed if the patient had at least 2 of 4 variables (hypothermia/fever, tachycardia, tachypnea, and leukocytosis/leukopenia) within 4 days of admission. Clinical outcome was measured on the Glasgow outcome scale 3 months after SAH. The relationship between clinical and radiologic variables and SIRS, angiographic vasospasm, delayed ischemic neurologic deficit (DIND), cerebral infarction, vasospasm-related infarction, and clinical outcome were modeled with uni- and multivariable analyses.

RESULTS

63% of patients developed SIRS. Many factors were associated with SIRS in univariate analysis, but only poor WFNS grade and pneumonia were independently associated with SIRS in multivariable analysis. SIRS burden (number of SIRS variables per day over the first 4 days) was associated with poor outcome, but not with angiographic vasospasm, DIND, or cerebral infarction. The method of aneurysm treatment was not associated with SIRS.

CONCLUSION

SIRS was associated with poor outcome but not angiographic vasospasm, DIND, or cerebral infarction after SAH in the CONSCIOUS-1 data. There was no support for the notion that neurosurgical clipping is associated with a greater risk of SIRS than endovascular coiling.

Causes of neurological deficits following clipping of 200 consecutive ruptured aneurysms in patients with good-grade aneurysmal subarachnoid haemorrhage

BACKGROUND

The surgical risk of unruptured aneurysms is well quantified. Although the outcomes for ruptured aneurysms are also well described, due to the concurrent morbidity from the natural history of the haemorrhage, the relative contributions of surgery and natural history to outcome following aneurysmal subarachnoid haemorrhage (SAH) is not. Our aim was to quantify these risks.

METHODS

This was a retrospective case note and radiological review of 200 patients with aneurysmal World Federation of Neurological Surgeons grade 1 or 2 SAH, treated with surgical clipping over a period of 3 years. Cases were reviewed to establish the incidence of surgical complications. Outcome was assessed at 3-month follow-up on Glasgow outcome score and the influence of surgical complications on this was assessed.

RESULTS

Thirty-seven patients suffered a surgical complication (19%). Over one half (19/37) were due to a vascular injury and 13 of those resulted in an unfavourable outcome (7% of all operations). The remainder of the patients who suffered a surgical complication (18/37) included those with direct brain injury, cranial nerve injury, post-operative haematoma and bone flap infection. Of those, only two cases resulted in poor outcome (1% of operations). In total, 22 patients had an unfavourable outcome (11%). In 15 (8%), surgical complications were deemed the major contributory factor.

CONCLUSIONS

Overall, surgically treated good-grade SAH has a good outcome. The majority of poor outcomes are due to surgical complications and most of these are vascular. Careful preservation of perforators and accurate clip placement remain the key factors in determining outcome in surgically treated good-grade SAH.

Intraventricular hemorrhage volume predicts poor outcomes but not delayed ischemic neurological deficits among patients with ruptured cerebral aneurysms

BACKGROUND

Intraventricular hemorrhage (IVH) predicts worse outcomes following aneurysmal subarachnoid hemorrhage (SAH). One potential mechanism is that IVH predisposes to the development of delayed ischemic neurological deficits (DINDs). No previous studies have evaluated the association between IVH volume (in milliliters) and subsequent development of DINDs or poor outcomes.

OBJECTIVE

To assess the association between the volume of IVH and the subsequent development of DINDs, delayed cerebral infarction, death, and poor neurological outcomes, specifically among patients with concomitant SAH and IVH.

METHODS

We performed a cohort study involving 152 consecutive patients with concomitant SAH and IVH. To determine volume of IVH, we used the IVH Score, shown to correlate well with computerized volumetric assessment. To determine the relative quantity of subarachnoid blood, we applied the SAH Sum Score. Multivariate logistic regression was used to adjust for potential confounders.

RESULTS

There was no significant association between IVH volume and the development of DINDs or delayed infarction. In contrast, patients with poor neurological outcomes had significantly larger baseline IVH volume (mean, 11.8 mL vs 3.8 mL, P = .001). In the multivariate analysis, IVH volume was an independent predictor of poor outcomes (OR per mL: 1.11 [1.04-1.18]). Patients in the highest quartile for IVH volume were far more likely to progress to poor outcome compared with those in the lowest quartile (OR 4.09 [1.32-12.65]). Interobserver agreement in the determination of IVH Score was moderate to good.

CONCLUSIONS

IVH volume is an independent predictor of poor neurological outcomes, even after adjusting for the amount of subarachnoid blood. The pathophysiology of this association does not appear to involve an increased risk of DINDs or delayed infarction. Measures aimed at accelerating IVH clearance, such as intraventricular thrombolysis, merit further evaluation.

Nicardipine pellets for the prevention of cerebral vasospasm

Regardless of numerous efforts there is no prophylactic treatment proven to be effective in the prevention of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH). As systemic administration of vasoactive drugs has been associated with significant side effects and insufficient efficacy, intrathecal administration of nicardipine prolonged-release implants (NPRI) has been developed. At the time of surgical clipping of the ruptured aneurysm, NPRIs are positioned next to the large cerebral arteries. Several clinical protocols revealed that NPRIs dramatically reduce the incidence and severity of angiographic vasospasm, which was paralled by a reduction in cerebral infarction and delayed ischemic neurologic deficit. On average, the incidence of angiographic vasospasm decreased from approximately 70% to less than 10%. Efficacy seemed to be dose-dependent and reduced for peripheral vasospasm. Nevertheless, a significant improvement of functional outcome was demonstrated. A separate patient series demonstrated the efficacy of fewer NPRIs in the perichiasmatic cistern. Further investigations were performed in comparison to coiled patients and with intraventricular implantation of NPRIs, which had a less pronounced effect. Overall, NPRIs are a most promising option for the prevention of cerebral vasospasm after SAH and large controlled trials are needed to further confirm these results.

Spreading depolarization: a possible new culprit in the delayed cerebral ischemia of subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating disease with a high mortality and morbidity rate. Gradual improvements have been made in the reduction of mortality rates associated with the disease during the last 30 years. However, delayed cerebral ischemia (DCI), the major delayed complication of SAH, remains a significant contributor to mortality and morbidity despite substantial research and clinical efforts. During the last several years, the predominant role of cerebral vasospasm, the long-accepted etiologic factor behind DCI, has been questioned. It is now becoming increasingly clear that the pathophysiology underlying DCI is multifactorial. Cortical spreading depression is emerging as a likely factor in this complex web of pathologic changes after SAH. Understanding its role after SAH and its relationship with the other pathologic processes such as vasospasm, microcirculatory dysfunction, and microemboli will be vital to the development of new therapeutic approaches to reduce DCI and improve the clinical outcome of the disease.

Clinical relevance of cortical spreading depression in neurological disorders: migraine, malignant stroke, subarachnoid and intracranial hemorrhage, and traumatic brain injury

Cortical spreading depression (CSD) and depolarization waves are associated with dramatic failure of brain ion homeostasis, efflux of excitatory amino acids from nerve cells, increased energy metabolism and changes in cerebral blood flow (CBF). There is strong clinical and experimental evidence to suggest that CSD is involved in the mechanism of migraine, stroke, subarachnoid hemorrhage and traumatic brain injury. The implications of these findings are widespread and suggest that intrinsic brain mechanisms have the potential to worsen the outcome of cerebrovascular episodes or brain trauma. The consequences of these intrinsic mechanisms are intimately linked to the composition of the brain extracellular microenvironment and to the level of brain perfusion and in consequence brain energy supply. This paper summarizes the evidence provided by novel invasive techniques, which implicates CSD as a pathophysiological mechanism for this group of acute neurological disorders. The findings have implications for monitoring and treatment of patients with acute brain disorders in the intensive care unit. Drawing on the large body of experimental findings from animal studies of CSD obtained during decades we suggest treatment strategies, which may be used to prevent or attenuate secondary neuronal damage in acutely injured human brain cortex caused by depolarization waves.

Advances in treatment of cerebral vasospasm: an update

An update of published clinical advances in the treatment of cerebral vasospasm after subarachnoid haemorrhage was provided. Searching MEDLINE using the search terms "cerebral vasospasm" and "clinical trials" 46 papers were identified that had been published since the International Conference on Cerebral Vasospasm in Istanbul, Turkey in 2006. Of these 26 were either safety studies or case reports leaving 20 papers for consideration. The major topics covered were calcium antagonists, magnesium sulphate, statins, and fasudil hydrochloride. The studies published did not reach an impact justified recommended routine use, but certainly as options. Results of the CONSCIOUS trials on endothelin receptor antagonists are awaited.

Metamorphosis of subarachnoid hemorrhage research: from delayed vasospasm to early brain injury

Delayed vasospasm that develops 3–7 days after aneurysmal subarachnoid hemorrhage (SAH) has traditionally been considered the most important determinant of delayed ischemic injury and poor outcome. Consequently, most therapies against delayed ischemic injury are directed towards reducing the incidence of vasospasm. The clinical trials based on this strategy, however, have so far claimed limited success; the incidence of vasospasm is reduced without reduction in delayed ischemic injury or improvement in the long-term outcome. This fact has shifted research interest to the early brain injury (first 72 h) evoked by SAH. In recent years, several pathological mechanisms that activate within minutes after the initial bleed and lead to early brain injury are identified. In addition, it is found that many of these mechanisms evolve with time and participate in the pathogenesis of delayed ischemic injury and poor outcome. Therefore, a therapy or therapies focused on these early mechanisms may not only prevent the early brain injury but may also help reduce the intensity of later developing neurological complications. This manuscript reviews the pathological mechanisms of early brain injury after SAH and summarizes the status of current therapies.

Recombinant osteopontin in cerebral vasospasm after subarachnoid hemorrhage

OBJECTIVE

Osteopontin (OPN), a pleiotropic extracellular matrix glycoprotein, has been reported to be protective against ischemic lesions, but effects of OPN on vascular functions have not been investigated. The aim of this study was to assess whether recombinant OPN (r-OPN) could prevent cerebral vasospasm after subarachnoid hemorrhage (SAH) in rats.

METHODS

r-OPN was administered intraventricularly to rats undergoing SAH by endovascular perforation, and its protective effects were evaluated by measuring the diameter of cerebral arteries and neurobehavioral testing. Western blotting and immunofluorescence were performed to explore the underlying mechanisms. An integrin receptor antagonist GRGDSP or mitogen-activated protein kinase (MAPK) phosphatase (MKP)-1 small interfering RNA (siRNA) was also administered to r-OPN-treated SAH rats, and those effects were evaluated.

RESULTS

Pre-SAH administration of r-OPN prevented vasospasm and neurological impairments at 24-72 hours post-SAH. r-OPN enhanced an endogenous MAPK inhibitor, MKP-1, and suppressed the phosphorylation of MAPKs, caldesmon, and heat shock protein 27 in the spastic cerebral arteries at 24 hours post-SAH. Immunofluorescence revealed that MKP-1 was induced in the arterial smooth muscle layer. GRGDSP prevented r-OPN-induced MKP-1 upregulation, and MKP-1 siRNA abolished both MAPK inactivation and anti-vasospastic effects by r-OPN. Post-SAH r-OPN treatment also prevented vasospasm.

INTERPRETATION

r-OPN induced MKP-1 in the spastic cerebral arteries via binding to L-arginyl-glycyl-L-aspartate-dependent integrin receptors and prevented vasospasm after SAH. Therapeutic induction of MKP-1 may be a novel approach for the prevention and treatment of cerebral vasospasm.

Cerebrospinal fluid pentraxin 3 early after subarachnoid hemorrhage is associated with vasospasm

PURPOSE

To investigate plasma and cerebrospinal fluid (CSF) concentrations of pentraxin 3 (PTX3), a prototypic long pentraxin protein induced by proinflammatory signals, in subarachnoid hemorrhage (SAH), and its relation with SAH-associated vasospasm.

METHODS

Serial plasma and CSF samples were collected from 38 consecutive SAH patients admitted to the Neurosurgical Intensive Care. PTX3 concentrations were analyzed in relation to clinical status and clinical vasospasm (defined as neuro-worsening and angiographic confirmation of vessel narrowing). Since neutrophils are an important source of preformed PTX3, myeloperoxidase (MPO) in CSF was measured to assess the correlation with CSF PTX3 and establish whether blood contamination was the determinant of PTX3 increase.

RESULTS

PTX3 was elevated in all SAH patients both in plasma and CSF. Acute peak (first 48 h after SAH) CSF PTX3 was significantly higher in patients who later developed vasospasm [median 13.6 (range 2.3-51.9) ng/ml] compared to those who did not [3.2 (0.1-50.5) ng/ml, p = 0.03]. The temporal pattern of CSF PTX3 in patients with vasospasm was triphasic with a peak during the first 48 h after SAH, a subsequent decrease in the following 48-96 h and a secondary significant increase with the occurrence of vasospasm. A loose correlation between CSF PTX3 and MPO was observed (r(2) = 0.13), indicating that following SAH there is a brain production of PTX3.

CONCLUSIONS

Acute increased concentrations of PTX3 in CSF but not in plasma are related to the occurrence of vasospasm, indicating that measurement of CSF PTX3 associated with the clinical evaluation can improve early diagnosis of this complication.

A review of delayed ischemic neurologic deficit following aneurysmal subarachnoid hemorrhage: historical overview, current treatment, and pathophysiology

Delayed ischemic neurologic deficit (DIND) is a serious and poorly understood complication of aneurysmal subarachnoid hemorrhage. Although advances in treatment have improved prognosis for these patients, long-term clinical outcomes remain disappointing. Historically, angiographic vasospasm was thought to result in a DIND, although an increasing body of evidence suggests that this is an oversimplification, because interventions that have effectively targeted angiographic vasospasm have not improved outcome. Consequently, the relationship between angiographic vasospasm and neurologic outcome may be associative rather than causative. Although our understanding of the underlying molecular processes and pathophysiology is improving, responsible mediators or pathways have yet to be identified. The aim of this review is to summarize the key historical events that have helped shape our understanding of the pathophysiology of this phenomenon (microcirculation, autoregulation, microthrombosis, inflammation, apoptosis, spreading depolarization, oxidative stress) and to present the evidence underlying current treatment strategies (hemodynamic therapy, oral nimodipine, endovascular therapy, statins, cerebrospinal fluid drainage, thrombolysis, magnesium) and the translational and clinical research investigating DIND.

Neuroprotection in subarachnoid hemorrhage

Despite advances in aneurysm ablation and the initial management of patients presenting with aneurysmal subarachnoid hemorrhage, delayed cerebral ischemia remains a significant source of morbidity. Traditionally, delayed cerebral ischemia was thought to be a result of vasospasm of the proximal intracranial vessels, and clinical trials have relied largely on radiographic evidence of vasospasm as a surrogate for functional outcome. However, a number of trials have demonstrated a dissociation between angiographic vasospasm and outcome, and more recent data suggest that other mechanisms of injury, such as microvascular dysfunction and complex neuronal-glial interactions, may influence the development of delayed ischemic deficit after aneurysmal subarachnoid hemorrhage. Our evolving understanding of the pathophysiology of delayed cerebral ischemia may offer the opportunity to test new therapeutic strategies in this area and improve clinical trial design.

Patient Age and Vasospasm After Subarachnoid Hemorrhage

BACKGROUND:

Subarachnoid hemorrhage (SAH) from a ruptured intracranial aneurysm is a devastating disease with high mortality and morbidity. The incidence of SAH increases with advancing age.

OBJECTIVE:

To determine whether age is an independent predictor of angiographic vasospasm, delayed ischemic neurological deficits (DINDs), or abnormal transcranial Doppler (TCD) measurements in patients with aneurysmal subarachnoid hemorrhage.

METHODS:

Data from CONSCIOUS-1 (Clazosentan to Overcome Neurological Ischemia and Infarct Occurring After Subarachnoid Hemorrhage study), a dose-finding study of clazosentan, were used. Data on angiographic vasospasm, DINDs, and TCD abnormalities were prospectively recorded as well as baseline characteristics and treatment data. Patient age was considered in 3 ways: as a continuous variable, dichotomized at age 65 years, and categorized by decade. Age was investigated as the main variable, whereas other possible confounding variables were adjusted for in the multiple logistic regression modeling with each of 3 dichotomized vasospasm outcome measures, presence or absence of angiographic vasospasm, DINDs, and TCD abnormalities as the dependent variable.

RESULTS:

The proportions of patients with angiographic vasospasm, DINDs, and TCD abnormalities were 45%, 19%, and 81%, respectively. Age, whether considered as a continuous, dichotomous, or a categorical variable, was not significantly associated with angiographic vasospasm, DINDs, or abnormal TCD measurements.

CONCLUSION:

Age does not seem to be a significant predictor for cerebral vasospasm after subarachnoid hemorrhage.

Alteration in voltage-dependent calcium channels in dog basilar artery after subarachnoid hemorrhage

Object

The L-type Ca++ channel antagonists like nimodipine have limited efficacy against vasospasm after subarachnoid hemorrhage (SAH). The authors tested the hypothesis that this is because SAH alters these channels, rendering them less responsible for contraction.

Methods

Basilar artery smooth muscle cells were isolated 4, 7, and 21 days after SAH in dogs, and Ca++ channel currents were recorded in 10-mmol/L barium. Proteins for α1 subunits of L-type Ca++ channels were measured by immunoblotting and isometric tension recordings done on rings of the basilar artery.

Results

High voltage–activated (HVA) Ca++ channel currents were significantly decreased and low voltage–activated (LVA) currents increased during vasospasm 4, 7, and 21 days after SAH (p < 0.05). Vasospasm was associated with a significant decrease in the number of cells with negligible LVA current while the number of cells in which the LVA current formed greater than 50% of the maximal current increased (p < 0.01). Window currents through LVA and HVA channels were significantly reduced. All changes correlated with the severity of vasospasm. There was an increase in protein for Cav3.1 and Cav3.3 α1 subunits that comprise T-type Ca++ channels, a decrease in L-type (Cav1.2 and Cav1.3) and an increase in R-type (Cav2.3) Ca++ channel α1 subunits. Functionally, however, isometric tension studies showed vasospastic arteries still relaxed with nimodipine.

Conclusions

Voltage-dependent Ca++ channels are altered in cerebral arteries after SAH. While decreased L-type channels may account for the lack of efficacy of nimodipine clinically, there may be other reasons such as inadequate dose, effect of nimodipine on other cellular targets, and mechanisms of vasospasm other than smooth muscle contraction mediated by activation of L-type Ca++ channels.

Cerebral watershed hypoperfusion in subarachnoid hemorrhage: computed tomography perfusion analysis

OBJECT

A better understanding of the pathophysiology of vasospasm-induced delayed cerebral ischemia and earlier detection of hypoperfusion before ischemic injury are needed to guide therapy in subarachnoid hemorrhage (SAH). The cerebrovascular physiology of the major arterial territories differs from that of the watershed zones (WZs) in a way that would suggest a differential topographic sensitivity of the brain to vasospasm. The primary end point of the study was to investigate the vasospasm-induced hypoperfusion in relation to cerebrovascular topography and timing from the onset of SAH.

METHODS

Forty-one patients were prospectively enrolled and scheduled for perfusion-weighted (PW) CT at 3 time points (≤ 3 days, Days 4-8, and Days 9-15 after SAH). Perfusion-weighted CT maps were visually assessed for side-to-side perfusion asymmetry. The PW CT topographic pattern was categorized into absence of asymmetry, WZ, and vascular territory hypoperfusion. Perfusion-weighted CT revision was performed by investigators blinded to clinical information. The null hypothesis for the primary end point was that there would be no difference in hypoperfusion space-time distribution among the different vascular territories. Multivariate logistic regression and Cox proportional hazards modeling were used for statistical analysis.

RESULTS

Delayed cerebral ischemia occurred in 26 patients and its predicting variables were increasing age (p = 0.045), Fisher grade (p = 0.007), and hypoperfusion on the PW CT performed within the 1st 72 hours after SAH (p = 0.004). The timing of the PW CT with respect to the day of SAH affected the topographic pattern of hypoperfusion: watershed-zone hypoperfusion was more common within the first 3 days after SAH (p = 0.018), while the proportion of territorial hypoperfusion increased subsequently. Among the different covariates, a young age was independently associated with a higher risk of developing hypoperfusion in the WZs (p = 0.02).

CONCLUSIONS

This study suggests the existence of a cerebral topographic heterogeneity to the hemodynamic effects of SAH and differential pathogenetic mechanisms of hypoperfusion according to timing, age, and brain topography. Hypoperfusion in the WZs may be an early precursor to more profound ischemic events. The PW CT detection of such brain-sensitive zones could offer a warning signal of the early hemodynamic effects of SAH and cerebral vasospasm.

Definition of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage as an outcome event in clinical trials and observational studies: proposal of a multidisciplinary research group

BACKGROUND AND PURPOSE

In clinical trials and observational studies there is considerable inconsistency in the use of definitions to describe delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage. A major cause for this inconsistency is the combining of radiographic evidence of vasospasm with clinical features of cerebral ischemia, although multiple factors may contribute to DCI. The second issue is the variability and overlap of terms used to describe each phenomenon. This makes comparisons among studies difficult.

METHODS

An international ad hoc panel of experts involved in subarachnoid hemorrhage research developed and proposed a definition of DCI to be used as an outcome measure in clinical trials and observational studies. We used a consensus-building approach.

RESULTS

It is proposed that in observational studies and clinical trials aiming to investigate strategies to prevent DCI, the 2 main outcome measures should be: (1) cerebral infarction identified on CT or MRI or proven at autopsy, after exclusion of procedure-related infarctions; and (2) functional outcome. Secondary outcome measure should be clinical deterioration caused by DCI, after exclusion of other potential causes of clinical deterioration. Vasospasm on angiography or transcranial Doppler can also be used as an outcome measure to investigate proof of concept but should be interpreted in conjunction with DCI or functional outcome.

CONCLUSIONS

The proposed measures reflect the most relevant morphological and clinical features of DCI without regard to pathogenesis to be used as an outcome measure in clinical trials and observational studies.

Low patient enrollment sites in multicenter randomized clinical trials of cerebrovascular diseases: associated factors and impact on trial outcomes

Wide variability in patient enrollment among participating sites is a common phenomenon in multicenter trials. We examined stroke trial-related factors associated with the proportion of sites with low patient enrollment and the effect of these low-enrollment sites on trial outcome. We identified efficacy clinical trials enrolling patients with cerebrovascular diseases between 1980 and 2008 using an electronic database. The trials included in our analyses were multicenter randomized controlled trials (RCTs) comparing efficacy endpoints between two or more treatment groups and having >5 sites. Sites enrolling <10 patients or <2% of total trial patients were defined as low- enrollment sites. Trials were classified into tertiles based on the proportion of low-enrollment sites. Factors associated with trials that could be ascertained through a systematic review of published data were identified and examined. The association between low enrollment and a conclusive trial designation (defined by the ability to reject the primary null hypothesis either at or before target enrollment or demonstrate equivalence/noninferiority with adequate statistical power, depending on the initial design) was assessed using a multivariate logistic regression model. We identified 51 trials that met the inclusion criteria and provided information regarding patients enrolled per center. A total of 3059 participating centers enrolled a total of 53,742 trial participants; 78% of the participating sites enrolled <2% of trial participants. Trials enrolling acute stroke patients (within 24 hours of symptom onset) or those evaluating endovascular/surgical intervention had a higher proportion of low-enrollment sites (<10 patients per site). Studies with a higher proportion of low-enrollment sites were more likely to target acute stroke patients and less likely to randomize ≥1000 patients, use general efficacy endpoints, and stratify by site. There was no association between the studies with a higher proportion of low-enrollment sites and designation as a conclusive trial. A better understanding of factors associated with low-enrollment sites in clinical trials and the impact on a trial's ability to demonstrate conclusive outcomes may lead to strategies to make trial enrollments more efficient and cost-effective.

Current and future treatment considerations in the management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a type of hemorrhagic stroke that can cause significant morbidity and mortality. Although guidelines have been published to help direct the care of these patients, there is insufficient quality literature regarding the medical and pharmacological management of patients with aSAH. Treatment is divided into 3 categories: supportive therapy, prevention of complications, and treatment of complications. There are numerous pharmacological therapies that are targeted at prevention and treatment of the neurological and medical complications that may arise. Rebleeding, hydrocephalus, cerebral vasospasm, and seizures are the most common neurological complications while the most common medical complications include hyponatremia, pulmonary edema, cardiac arrhythmias, neurogenic stunned myocardium, fever, anemia, infection, hyperglycemia, and venous thromboembolism. Risk factors, clinical presentation, diagnosis, pathophysiology, as well as initial management, prevention, and treatment of complications will be the focus of this discussion.

Experimental and preliminary clinical evidence of an ischemic zone with prolonged negative DC shifts surrounded by a normally perfused tissue belt with persistent electrocorticographic depression

In human cortex it has been suggested that the tissue at risk is indicated by clusters of spreading depolarizations (SDs) with persistent depression of high-frequency electrocorticographic (ECoG) activity. We here characterized this zone in the ET-1 model in rats using direct current (DC)-ECoG recordings. Topical application of the vasoconstrictor endothelin-1 (ET-1) induces focal ischemia in a concentration-dependent manner restricted to a region exposed by a cranial window, while a healthy cortex can be studied at a second naïve window. SDs originate in the ET-1-exposed cortex and invade the surrounding tissue. Necrosis is restricted to the ET-1-exposed cortex. In this study, we discovered that persistent depression occurred in both ET-1-exposed and surrounding cortex during SD clusters. However, the ET-1-exposed cortex showed longer-lasting negative DC shifts and limited high-frequency ECoG recovery after the cluster. DC-ECoG recordings of SD clusters with persistent depression from patients with aneurysmal subarachnoid hemorrhage were then analyzed for comparison. Limited ECoG recovery was associated with significantly longer-lasting negative DC shifts in a similar manner to the experimental model. These preliminary results suggest that the ischemic zone in rat and human cortex is surrounded by a normally perfused belt with persistently reduced synaptic activity during the acute injury phase.

Biomarkers and vasospasm after aneurysmal subarachnoid hemorrhage

Subarachnoid hemorrhage from the rupture of a saccular aneurysm is a devastating neurological disease that has a high morbidity and mortality not only from the initial hemorrhage, but also from the delayed complications, such as cerebral vasospasm. Cerebral vasospasm can lead to delayed ischemic injury 1 to 2 weeks after the initial hemorrhage. Although the pathophysiology of vasospasm has been described for decades, the molecular basis remains poorly understood. With the many advances in the past decade in the development of sensitive molecular biological techniques, imaging, biochemical purification, and protein identification, new insights are beginning to reveal the etiology of vasospasm. These findings will not only help to identify markers of vasospasm and prognostic outcome, but will also yield potential therapeutic targets for the treatment of this disease. This review focuses on the methods available for the identification of biological markers of vasospasm and their limitations, the current understanding as to the utility and prognostic significance of identified biomarkers, the utility of these biomarkers in predicting vasospasm and outcome, and future directions of research in this field.

Improvement in neurological outcome and abolition of cerebrovascular endothelin B and 5-hydroxytryptamine 1B receptor upregulation through mitogen-activated protein kinase kinase 1/2 inhibition after subarachnoid hemorrhage in rats

OBJECT

Delayed cerebral ischemia after subarachnoid hemorrhage (SAH) remains a major cause of death and disability. It has been hypothesized that cerebrovascular upregulation of vasoconstrictor receptors is a key step in the development of delayed cerebral ischemia. Upregulation of endothelin-B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors has been demonstrated in cerebral artery smooth muscles in the delayed ischemic phase after experimental SAH, and intracellular signaling via the mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase 1/2 pathway has been shown to be involved in this upregulation. The aim in the present study was to determine whether treatment with the MEK1/2 inhibitor U0126 can prevent cerebrovascular receptor upregulation and improve functional outcome after experimental SAH in rats.

METHODS

Subarachnoid hemorrhage was induced in male Sprague-Dawley rats by the injection of 250 μl of autologous blood into the basal cisterns. Either U0126 or vehicle was intracisternally administered at 6, 12, 24, and 36 hours after SAH. Smooth muscle ET(B) and 5-HT(1B) receptor upregulation was studied in isolated cerebral artery segments through immunohistochemical and myographic studies of contractile responses to receptor-specific agonists. Gross sensorimotor function in the rats after SAH was assessed using a rotating pole test.

RESULTS

Contractile concentration-response curves for middle cerebral artery (MCA) and basilar artery (BA) segments to endothelin-1 (ET-1) and 5-carboxamidotryptamine (5-CT) were shifted leftward for SAH-induced compared with shamoperated rats due to enhanced contractile responses to individual doses of the agonists (for example, contractile responses of the BA to 3 × 10(-10) M of ET-1 and 3 × 10(-7) M of 5-CT were 9.98 ± 5.01% and 16.75 ± 3.62% of the maximal contractile capacity, respectively, in sham-operated rats and 62.78 ± 9.9% and 45.44 ± 10.62%, respectively, in SAH-induced rats). In vivo treatment with 0.19 μg/kg U0126 normalized responses in the SAH-induced rats to levels in the sham-operated rats. Protein expression of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles from SAH-induced rats was increased to 175 ± 33.17% and 167.7 ± 24.74%, respectively, of the levels in sham-operated rats. Endothelin-B and 5-HT(1B) expression levels in U0126-treated SAH-induced rats were at the levels in sham-operated rats (101.9 ± 13.38% and 91.44 ± 16.75%, respectively). In a rotating pole test used to assess gross sensorimotor function on the 2nd day after surgery, sham-operated rats achieved an average score of 5.37 ± 0.23, SAH-induced rats scored 3.35 ± 0.67, and SAH-induced U0126-treated rats scored 5.00 ± 0.4.

CONCLUSIONS

The authors demonstrated that experimental SAH induces upregulation of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles and that treatment with the MEK1/2 inhibitor U0126 abolishes this receptor upregulation. They also demonstrated that experimental SAH results in sensorimotor deficits as assessed by a rotating pole test. These deficits were alleviated by U0126 treatment, suggesting that cerebrovascular receptor upregulation is critical for the functional outcome of delayed cerebral ischemia. The authors suggest that inhibition of MEK1/2 may be a promising new SAH treatment strategy.

Statins in the management of patients with aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

BACKGROUND

Delayed ischemic neurological deficits (DINDs) contribute to morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). Based on promising preliminary reports, some clinicians routinely administer statins to prevent DINDs.

METHODS

Without language restriction, we searched MEDLINE, EMBASE, the Cochrane Central Register, references of review articles, proceedings of the International Stroke Conference, and gray literature sources. Studies were selected if they compared outcomes between statin-treated and untreated patients during the 2 weeks following SAH. Data were extracted and appraised independently and in duplicate, using standardized forms. Fixed or random effects models, as appropriate based on the degree of study heterogeneity, were applied to calculate summary measures.

RESULTS

Four RCTs, two "pseudo" RCTs, five cohort studies, and one case-control study met eligibility criteria. In the RCTs, which enrolled a total of 309 patients, statins were found to significantly reduce the occurrence of DINDs [OR 0.38 (0.23-0.65); P < 0.001], but not mortality [OR 0.51 (0.25-1.02); P = 0.06] or poor neurological recovery [OR 0.81 (0.49-1.32); P = 0.39]. Observational studies assessed 1,542 patients, of whom 385 received statins. Statin-use was not associated with any reduction in DINDs [OR 0.96 (0.71-1.31); P = 0.80], mortality [OR 1.16 (0.78-1.73); P = 0.47] or poor neurological recovery [OR 1.20 (0.84-1.72); P = 0.31]. When the results of all studies were combined, statins had no statistically significant effect.

CONCLUSIONS

Existing RCTs suggest that statins reduce DINDs, with a possible trend toward lower mortality. These findings are not supported by observational research. Although not assessed in all studies, current data do not indicate that statins improve neurological outcomes.

Endothelin--biology and disease

Endothelins are important mediators of physiological and pathophysiologic processes including cardiovascular disorders, pulmonary disease, renal diseases and many others. Additionally, endothelins are involved in many other important processes such as development, cancer biology, wound healing, and even neurotransmission. Here, we review the cell and molecular biology as well as the prominent pathophysiological aspects of the endothelin system.