Molecular keys to the problems of cerebral vasospasm

Brain ischemia in patients with intracranial hemorrhage: pathophysiological reasoning for aggressive diagnostic management

Patients with intracranial hemorrhage have to be managed aggressively to avoid or minimize secondary brain damage due to ischemia, which contributes to high morbidity and mortality. The risk of brain ischemia, however, is not the same in every patient. The risk of complications associated with an aggressive prophylactic therapy in patients with a low risk of brain ischemia can outweigh the benefits of therapy. Accurate and timely identification of patients at highest risk is a diagnostic challenge. Despite the availability of many diagnostic tools, stroke is common in this population, mostly because the pathogenesis of stroke is frequently multifactorial whereas diagnosticians tend to focus on one or two risk factors. The pathophysiological mechanisms of brain ischemia in patients with intracranial hemorrhage are not yet fully elucidated and there are several important areas of ongoing research. Therefore, this review describes physiological and pathophysiological aspects associated with the development of brain ischemia such as the mechanism of oxygen and carbon dioxide effects on the cerebrovascular system, neurovascular coupling and respiratory and cardiovascular factors influencing cerebral hemodynamics. Consequently, we review investigations of cerebral blood flow disturbances relevant to various hemodynamic states associated with high intracranial pressure, cerebral embolism, and cerebral vasospasm along with current treatment options.

Smooth muscle phenotype switching in blast traumatic brain injury-induced cerebral vasospasm

Due to increased survival rates among soldiers exposed to explosive blasts, blast-induced traumatic brain injury (bTBI) has become much more prevalent in recent years. Cerebral vasospasm (CVS) is a common manifestation of brain injury whose incidence is significantly increased in bTBI. CVS is characterized by initial vascular smooth muscle cell (VSMC) hypercontractility, followed by prolonged vessel remodeling and lumen occlusion, and is traditionally associated with subarachnoid hemorrhage (SAH), but recent results suggest that mechanical injury during bTBI can cause mechanotransduced VSMC hypercontractility and phenotype switching necessary for CVS development, even in the absence of SAH. Here, we review the mechanisms by which mechanical stimulation and SAH can synergistically drive CVS progression, complicating treatment options in bTBI patients.

Significance of C-reactive protein and transcranial Doppler in cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Objective

Cerebral vasospasm is a common and potentially devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). Inflammatory processes seem to play a major role in the pathogenesis of vasospasm. C-reactive protein (CRP) constitutes a highly sensitive inflammatory marker. Elevation of serum CRP levels has been demonstrated in patients with aSAH. The purpose of the current study was to evaluate the possible relationship between CRP levels in the serum and transcranial Doppler (TCD) and the development of vasospasm in patients with aSAH.

Methods

A total of 61 adult patients in whom aSAH was diagnosed were included in the study from November 2008 to May 2011. The patients' demographics, Hunt and Hess grade, Fisher grade, CT scans, digital subtraction angiography studies, and daily neurological examinations were recorded. Serial serum CRP measurements were obtained on days 1, 3, 5, 7, 9, 11 and 13 and TCD was measured on days 3, 5, 7, 9, 11 and 13. All patients underwent either surgical or endovascular treatment within 24 hours of their hemorrhagic attacks.

Results

Serum CRP levels peaked on the 3rd postoperative day. There were significant differences between the vasospasm group and the non-vasospasm group on the 1st, 3rd and 5th day. There were significant differences between the vasospasm group and the non-vasospasm group on the 3rd day in the mean middle cerebral artery velocities on TCD.

Conclusion

Patients with high levels of CRP on the 1st postoperative day and high velocity of mean TCD on the 3rd postoperative day may require closer observation to monitor for the development of vasospasm.

Effect of treatment with simvastatin and cyclosporine on neurotransmitter concentrations in cerebrospinal fluid after subarachnoid hemorrhage in dogs

OBJECTIVE

To measure concentrations of glutamate, aspartate, γ-aminobutyric acid (GABA), and glycine in CSF of dogs with experimentally induced subarachnoid hemorrhage (SAH) and to assess effects of cyclosporine and simvastatin on these concentrations.

SAMPLE

CSF samples from 13 dogs.

PROCEDURES

In a previous study, SAH was induced in dogs via 2 injections of autologous blood into the cerebellomedullary cistern 24 hours apart. Dogs were untreated (control; n = 5) or received simvastatin alone (4) or simvastatin in combination with cyclosporine (4). Samples of CSF were collected before the first blood injection (baseline; time 0), before the second blood injection, and on days 3, 7, and 10. For the study reported here, neurotransmitter concentrations in CSF were analyzed via high-performance liquid chromatography. Data were analyzed with a repeated-measures model with adjustments for multiple comparisons by use of the Tukey method.

RESULTS

In control dogs, the glutamate concentration peaked on day 3 and there was a significant increase in GABA and glutamate concentrations. Glutamate concentrations were significantly lower and glycine concentrations significantly higher on day 3 after administration of simvastatin alone or simvastatin in combination with cyclosporine, compared with concentrations for the control group. No significant differences in GABA and aspartate concentrations were detected among treatment groups at any time point.

CONCLUSIONS AND CLINICAL RELEVANCE

Glutamate concentrations were increased in the CSF of dogs with SAH. Simvastatin administration attenuated high glutamate concentrations. A combination of immunosuppression and upregulation of nitric oxide synthase may be useful in lowering high glutamate concentrations in ischemic CNS conditions.

Study the effects of zonisamide on fine structure of rabbit basilar artery and hippocampus in rabbit subarachnoid hemorrhage model

BACKGROUND

In this study, we investigated the effect of a novel antiepileptic drug, zonisamide (ZNS), on the basilar artery and hippocampus in a rabbit subarachnoid hemorrhage (SAH) model.

METHODS

Three groups of New Zealand white rabbits were used: a sham (non-SAH) group, an SAH + saline group, and SAH + drug treatment group that received ZNS. In the treatment group, the subjects were given ZNS for 3 days after the SAH. Hippocampal sections were evaluated for neural tissue degeneration. Basilar artery lumen areas and arterial wall thickness were also measured in all groups.

RESULTS

The mean luminal area of the SAH + ZNS was significantly greater than the SAH + saline group. In addition, the arterial wall thickness of SAH + ZNS group was significantly thinner than the SAH + saline group. The neuronal degeneration scores of the hippocampal CA1 regions in the SAH + ZNS group were significantly lower than the SAH + saline treatment animals.

CONCLUSIONS

These results indicate that ZNS has a vasodilatatory effect on the basilar artery and a neuronal protective effect in the CA1 region of the hippocampus in a rabbit SAH model.

Mechanisms of acute brain injury after subarachnoid hemorrhage

Brain injury after subarachnoid hemorrhage (SAH) is a biphasic event with an acute ischemic insult at the time of the initial bleed and secondary events such as cerebral vasospasm 3 to 7 days later. Although much has been learned about the delayed effects of SAH, less is known about the mechanisms of acute SAH-induced injury. Distribution of blood in the subarachnoid space, elevation of intracranial pressure, reduced cerebral perfusion and cerebral blood flow (CBF) initiates the acute injury cascade. Together they lead to direct microvascular injury, plugging of vessels and release of vasoactive substances by platelet aggregates, alterations in the nitric oxide (NO)/nitric oxide synthase (NOS) pathways and lipid peroxidation. This review will summarize some of these mechanisms that contribute to acute cerebral injury after SAH.

Subarachnoid hemorrhage, spreading depolarizations and impaired neurovascular coupling

Aneurysmal subarachnoid hemorrhage (SAH) has devastating consequences on brain function including profound effects on communication between neurons and the vasculature leading to cerebral ischemia. Physiologically, neurovascular coupling represents a focal increase in cerebral blood flow to meet increased metabolic demand of neurons within active regions of the brain. Neurovascular coupling is an ongoing process involving coordinated activity of the neurovascular unit-neurons, astrocytes, and parenchymal arterioles. Neuronal activity can also influence cerebral blood flow on a larger scale. Spreading depolarizations (SD) are self-propagating waves of neuronal depolarization and are observed during migraine, traumatic brain injury, and stroke. Typically, SD is associated with increased cerebral blood flow. Emerging evidence indicates that SAH causes inversion of neurovascular communication on both the local and global level. In contrast to other events causing SD, SAH-induced SD decreases rather than increases cerebral blood flow. Further, at the level of the neurovascular unit, SAH causes an inversion of neurovascular coupling from vasodilation to vasoconstriction. Global ischemia can also adversely affect the neurovascular response. Here, we summarize current knowledge regarding the impact of SAH and global ischemia on neurovascular communication. A mechanistic understanding of these events should provide novel strategies to treat these neurovascular disorders.

MELAS and reversible vasoconstriction of the major cerebral arteries

A 26-year-old woman was admitted due to an altered mental status and generalized tonic-clonic seizures. She had experienced chronic migraine-like headaches, progressive bilateral hearing loss, a short stature and nephrotic syndrome. Laboratory data showed elevated lactate and pyruvate levels. Brain MRI using diffusion-weighted imaging revealed a hyperintense lesion in the left temporal lobe. MR angiography revealed segmental stenosis at the C1 and M1-2 junction. A genetic study revealed a mitochondrial DNA A3243G point mutation. The patient's clinical symptoms and MRI/MR angiography (MRA) findings improved within four weeks. We herein discuss the possible pathophysiology involving both stroke-like episodes and reversible vasoconstriction.

Post-subarachnoid hemorrhage vasospasm in patients with primary headache disorders

BACKGROUND

Altered cerebral vasomotor reactivity leading to vasospasm can be seen both in patients with primary headache disorders (PHD) and in patients with subarachnoid hemorrhage (SAH). The pathogenesis of vasospasm in post-SAH patients and in headache disorder sufferers may be related. To address this hypothesis, we analyzed a large cohort of SAH patients to determine whether a diagnosis of PHD predisposes to vasospasm, delayed cerebral ischemia, or worsened clinical outcome.

METHODS

Prospectively collected data from patients enrolled in the SAH Outcomes Project between 1996 and 2006 were analyzed. Patients were segregated based on whether they had a diagnosis of PHD or not and were subsequently compared for differences in clinical and radiographic outcome.

RESULTS

A total of 921 SAH patients were analyzed, 265 of which had a diagnosis of PHD. In total, symptomatic vasospasm was seen in 17%, while angiographic vasospasm was seen in 28%. Vasospasm rates were similar among patients with a PHD and in those without a PHD (p > 0.05). However, on multivariate analysis new ischemic infarcts were more common in patients with a PHD as compared to patients without a PHD (p = 0.015). Functional outcomes at 3 months were similar among PHD and non-PHD patients (p > 0.05).

CONCLUSION

A history of PHD is associated with an increased rate of ischemic infarcts during admission for SAH. Increased rates of vasospasm within small cerebral blood vessels may be implicated. Further studies are warranted to more closely link the mechanisms of vasospasm in PHD and SAH patients.

Acupuncture for cerebral vasospasm after subarachnoid hemorrhage: a retrospective case-control study

OBJECTIVES

To examine the possibility of acupuncture as a new promising treatment to prevent delayed cerebral vasospasm, retrospective comparison was done of patient outcomes in patients with subarachnoid hemorrhage (SAH) treated with and without acupuncture.

MATERIALS AND METHODS

Twenty (20) patients with SAH were treated after their ruptured aneurysms had been secured. Acupuncture treatments were applied to the bilateral Zusanli (ST36) and Neiguan (PC6) once a day for 2 weeks, starting within 3 days of the aneurysm rupture. The incidence of angiographic vasospasm and delayed ischemic neurological deficit (DIND), the patient's functional status at discharge, and mortality rate were analyzed. Patient outcomes were compared with those of an age- and severity-matched comparison group composed of patients treated in the hospital without acupuncture.

RESULTS

None of the patients who received acupuncture died. Angiographic vasospasms occurred in 5 patients (25.0%) and DIND in 2 (10%). In terms of functional impairment, the modified Rankin score at discharge was ≤2 in 7 patients (35%). In the control group, angiographic vasospasms occurred in 10 patients (55.6%) and DIND in 7 (38.9%), similar to the reported incidence in conventionally treated patients.

CONCLUSIONS

Patients with SAH who received acupuncture had a significantly lower incidence of DIND and significantly improved function at discharge, suggesting that acupuncture is effective in preventing cerebral vasospasm. In light of these promising results, a randomized controlled trial is warranted to determine the efficacy of acupuncture in a clinical setting.

Influence of Fever and hospital-acquired infection on the incidence of delayed neurological deficit and poor outcome after aneurysmal subarachnoid hemorrhage

Although fever and infection have been implicated in the causation of delayed neurological deficits (DND) and poor outcome after aneurysmal subarachnoid hemorrhage (SAH), the relationship between these two often related events has not been extensively studied. We reviewed these events through of our retrospective database of patients with SAH. Multivariate logistic regression was used to determine independent predictors of DND and poor outcome. A total of 186 patients were analyzed. DND was noted in 76 patients (45%). Fever was recorded in 102 patients (55%); infection was noted in 87 patients (47%). A patient with one infection was more likely to experience DND compared to a patient with no infections (adjusted OR 3.73, 95% CI 1.62, 8.59). For those with more than two infections the likelihood of DND was even greater (adjusted OR 4.24, 95% CI 1.55, 11.56). Patients with 1-2 days of fever were less likely to have a favorable outcome when compared to their counterparts with no fever (adjusted OR 0.19, 95% CI 0.06, 0.62). This trend worsened as the number of days febrile increased. These data suggest that the presence of infection is associated with DND, but that fever may have a stronger independent association with overall outcome.

Anterior-posterior compression pelvic fracture increases the probability of requirement of bilateral embolization

INTRODUCTION

Transarterial embolization has become an effective method in the management of pelvic fracture-related retroperitoneal hemorrhage. However, the selection of bilateral embolization or selective unilateral embolization remains controversial. The anterior-posterior compression (APC) pelvic fracture creates a complete diastasis of the anterior pelvis, which might be associated with bilateral sacroiliac joint injuries and further bilateral arterial injuries. In the current study, we evaluated the correlation between APC pelvic fracture and the need for bilateral internal iliac artery (IIA) embolization.

METHODS

During the 78-month investigational period, patients who received either unilateral or bilateral IIA embolization over the injured site, as determined by angiographic findings, were enrolled. The patients with bilateral contrast extravasation (CE) revealed by angiography were compared with the patients with unilateral CE revealed by angiography. Among the patients with only unilateral positive findings (CE or hematoma formation) on computed tomographic scanning, the characteristics and risk factors of patients who required bilateral IIA embolization were analyzed. The patients with postembolization hemorrhage who had received repeat transarterial embolization were also identified and discussed.

RESULTS

Seventy patients were enrolled in the current study. The rate of APC pelvic fracture among patients who received bilateral IIA embolization was 66.7% (18/27), which was significantly higher than the rate among patients who received unilateral IIA embolization (30.2%; 3/43) (P = .006). Of the patients with only unilateral positive findings on computed tomographic scanning, 21.6% (11/51) underwent bilateral IIA embolization because of bilateral CE revealed by angiography. There were also more patients with APC pelvic fracture in this group.

CONCLUSION

In the management of APC pelvic fracture, more attention should be paid to the higher probability of bilateral hemorrhage. Bilateral IIA embolization should be considered in patients with APC pelvic fracture.

Reversible cerebral vasoconstriction syndrome: an important cause of acute severe headache

Reversible cerebral vasoconstriction syndrome (RCVS) is an increasingly recognized and important cause of acute headache. The majority of these patients develop potentially serious neurological complications. Rigorous investigation is required to exclude other significant differential diagnoses. Differentiating RCVS from subarachnoid haemorrhage (SAH) and primary angiitis of the central nervous system (PACNS) may be difficult but has important therapeutic implications. This paper describes what is currently known about the epidemiology, pathophysiology, clinical, and diagnostic features of the syndrome, an approach to investigation, a summary of treatments, and what is known of prognosis.

The role of sphingosine kinase 1/sphingosine-1-phosphate pathway in the myogenic tone of posterior cerebral arteries

Aims

The goal of the current study was to determine whether the sphingosine kinase 1 (SK1)/sphingosine-1-phosphate (S1P) pathway is involved in myogenic vasoconstriction under normal physiological conditions. In the present study, we assessed whether endogenous S1P generated by pressure participates in myogenic vasoconstriction and which signaling pathways are involved in SK1/S1P-induced myogenic response under normal physiological conditions.

Methods and Results

We measured pressure-induced myogenic response, Ca²⁺ concentration, and 20 kDa myosin light chain phosphorylation (MLC₂₀) in rabbit posterior cerebral arteries (PCAs). SK1 was expressed and activated by elevated transmural pressure in rabbit PCAs. Translocation of SK1 by pressure elevation was blocked in the absence of external Ca²⁺ and in the presence of mechanosensitive ion channel and voltage-sensitive Ca²⁺ channel blockers. Pressure-induced myogenic tone was inhibited in rabbit PCAs treated with sphingosine kinase inhibitor (SKI), but was augmented by treatment with NaF, which is an inhibitor of sphingosine-1-phosphate phosphohydrolase. Exogenous S1P further augmented pressure-induced myogenic responses. Pressure induced an increase in Ca²⁺ concentration leading to the development of myogenic tone, which was inhibited by SKI. Exogenous S1P further increased the pressure-induced increased Ca²⁺ concentration and myogenic tone, but SKI had no effect. Pressure- and exogenous S1P-induced myogenic tone was inhibited by pre-treatment with the Rho kinase inhibitor and NADPH oxidase inhibitors. Pressure- and exogenous S1P-induced myogenic tone were inhibited by pre-treatment with S1P receptor blockers, W146 (S1P1), JTE013 (S1P2), and CAY10444 (S1P3). MLC₂₀ phosphorylation was increased when the transmural pressure was raised from 40 to 80 mmHg and exogenous S1P further increased MLC₂₀ phosphorylation. The pressure-induced increase of MLC₂₀ phosphorylation was inhibited by pre-treatment of arteries with SKI.

Conclusions

Our results suggest that the SK1/S1P pathway may play an important role in pressure-induced myogenic responses in rabbit PCAs under normal physiological conditions.

Reversible cerebral vasoconstriction syndrome: current and future perspectives

Reversible cerebral vasoconstriction syndromes (RCVS) are characterized by recurrent acute severe headaches, namely thunderclap headaches, and multifocal segmental vasoconstrictions. Interest has arisen in the definitions, clinical presentations, differential diagnoses, risk factors and complications of RCVS. This article will comprehensively review the milestone monographs and the latest research work addressing these issues. Studies that have focused on the relationship between RCVS and thunderclap headache will be detailed. We will also discuss research on the enigmatic pathophysiology and potential therapeutic approaches. Up-to-date information and challenges, undergoing studies and future research directions will be deeply probed.

The use of nicardipine prolonged release implants (NPRI) in microsurgical clipping after aneurysmal subarachnoid haemorrhage: comparison with endovascular treatment

BACKGROUND

Nicardipine prolonged release implants (NPRI) have been shown to decrease the incidence of cerebral vasospasm and infarcts significantly in patients after aneurysmal subarachnoid haemorrhage (SAH) following microsurgical clipping. Yet, the comparison with results after endovascular coiling is lacking. This study was conducted to determine the differences in the incidence of cerebral vasospasm and infarctions between those two treatment modalities

METHODS

The design of this investigation reflects a case-control study; 27 patients suffering from acute SAH were treated by microsurgical clipping and received an intracisternal implantation of NPRI. Twenty-seven matching consecutive patients after microsurgical treatment without implantation of NPRI or endovascular treatment, respectively, served as controls. The incidence of angiographic vasospasm and cerebral infarctions were documented.

RESULTS

All groups were comparable concerning demographics and severity of SAH. Twenty-four of 81 patients developed angiographic vasospasm (>33% constriction). The incidence of vasospasm was 48%, 44% and 11% for patients after endovascular treatment, microsurgical clipping without NPRI and microsurgical clipping with NPRI, respectively. New cerebral infarctions occurred in 28%, 22% and 7% of the treated patients, respectively. A good clinical recovery 1 year after the initial bleeding (modified Rankin scale 0-2) was seen in 48%, 50% and 77% of the treated patients, respectively.

CONCLUSION

The use of NPRI during microsurgical clipping was confirmed to be safe and effective. Patients who received intracisternally implanted NPRI during clipping after aneurysmal SAH yielded significantly lower vasospasm and infarction rates, and showed a better clinical outcome when compared with clipping without NPRI and also when compared with endovascular coiling.

Effects of intramuscular parecoxib administration on vasospasm in an experimental subarachnoid hemorrhage model

AIM

We examined whether intramuscular parecoxib administration has a preventive or therapeutic effect on vasospasm following experimental subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

Twenty New Zealand White Rabbits were assigned randomly to one of four groups. Animals in Group I were not subjected to SAH (control group). Animals in all other groups were subjected to SAH. Animals in Group II received no treatment after SAH induction (SAH group). Animals in Group III received intramuscular parecoxib (diluted with saline) injection at 6 and at 30 hours after SAH (treatment group). Animals in Group IV received only intramuscular saline injection at 6 and at 30 hours after SAH (vehicle group). Animals were euthanized by perfusion and fixation 48 hours after SAH induction. Basilar artery cross-sectional areas and wall thicknesses were measured. Statistical comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

Basilar artery cross-sectional areas in the treatment group were significantly higher than in the SAH or vehicle group (p<.05). Basilar artery wall thickness in the treatment group was significantly smaller than in the SAH or vehicle group (p<.05).

CONCLUSION

Our study revealed that intramuscular administration of parecoxib significantly attenuates vasospasm following experimental SAH.

Treatment of subarachnoid hemorrhage with human albumin: ALISAH study. Rationale and design

The primary objective of this prospective dose-finding pilot study is to demonstrate the tolerability and safety of four dosages of 25% human albumin in patients with subarachnoid hemorrhage (SAH). For each dosage group, the study will enroll 20 patients who meet the eligibility criteria. The enrolled patients will undergo follow-up for 90 days post-treatment. The primary tolerability hypothesis is that intravenous 25% human albumin can be given without precipitating treatment related serious adverse events beyond expectations. The study will determine the maximum tolerated dosage of 25% human albumin therapy based on the rate of treatment related serious adverse events during treatment: severe or life-threatening heart failure. The secondary objectives are to obtain preliminary estimates of the albumin treatment effect using the incidence of neurological deterioration within 15 days after symptom onset. In addition, the incidence of rebleeding, hydrocephalus, seizures, delayed cerebral ischemia and the incidence of vasospasm (both symptomatic and by transcranial Doppler ultrasound criteria) within 15 days after symptom onset will be evaluated. Furthermore, the serum osmolality and serum albumin concentrations, serum magnesium concentration, blood pressure and heart rate within 15 days of symptom onset will also be observed. The Glasgow Outcome Scale, Barthel Index, modified Rankin Scale, NIH Stroke Scale, and Stroke Impact Scale will be performed 3 months after the onset of symptoms to assess residual neurological deficits.

The effects of Nigella sativa against oxidative injury in a rat model of subarachnoid hemorrhage

OBJECTIVE

The aim of the study was to investigate the putative neuroprotective effect of Nigella sativa oil (NSO) treatment against subarachnoid hemorrhage (SAH) in rats.

METHODS

To induce SAH, rats were injected with 0.3 ml blood into their cisterna magna. Male Wistar albino rats were divided as control, vehicle-treated SAH, and NSO-treated (0.2 ml/kg, intraperitoneally) SAH groups. Forty-eight hours after SAH induction, neurological examination scores were recorded and the rats were decapitated. Brain tissue samples were taken for blood brain barrier permeability, brain water content, or determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO), and Na(+)-K(+)-ATPase activities.

RESULTS AND DISCUSSION

On the second day of SAH induction, neurological examination scores were increased in SAH groups, while SAH caused significant decreases in brain GSH content and Na(+)-K(+)-ATPase activity, which were accompanied with significant increases in MDA levels and MPO activity. The histological observation showed vasospasm of the basillary artery. On the other hand, NSO treatment markedly improved the neurological scores while all oxidant responses were prevented, implicating that NSO treatment may be of therapeutic use in preventing oxidative stress due to SAH.

The correlation between COMT gene polymorphism and early cerebral vasospasm after subarachnoid hemorrhage

BACKGROUND

The individual difference of cerebral vasospasm (CVS) degree after subarachnoid hemorrhage (SAH) is common in clinic observation. Numerous studies have found that early CVS after SAH is associated with derangements in catecholamine (CA) metabolism. Catechol-O-methyltransferase (COMT) is a key rate-limiting enzyme in the degradation of CA. In this study, we investigate the correlation between COMT gene polymorphism of patients and early CVS after SAH.

METHODS

One hundred and sixty-seven patients with spontaneous SAH in early stage were selected in this study. COMT genotyping was performed by means of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The degree of CVS was identified by TCD. Hunt-Hess classification was used to evaluate the severity of the patients' condition. The bleeding amount was evaluated by means of Fisher classification of head CT. χ2 test (SPSS13.0 software) and logistic regression were adopted to analyze the correlation of COMT gene polymorphism and other clinical data of patients with early CVS after SAH.

RESULTS

The distribution of each allele matched Hardy-Weinberg law and research samples were heredity equilibrium population. Early CVS incidence of patients with COMT-A allele was much higher than those with COMT-G allele (P<0.01). Early CVS incidence of patients with COMT A/A genotype was obviously higher than those with COMT G/G genotype (P<0.05). Univariate logistic regression demonstrated that COMT-A allele, A/A genotype and Grade 3-5 of Hunt-Hess classification were all associated with early CVS. After adjustment of general information, further multivariate logistic regression demonstrated that COMT-A allele, A/A genotype were risk factors of early CVS after SAH.

CONCLUSION

COMT-A allele, A/A genotype were risk factors of early CVS after SAH.

Bilirubin oxidation products seen post subarachnoid hemorrhage have greater effects on aged rat brain compared to young

INTRODUCTION

We have previously shown that novel oxidation products of Bilirubin, called Bilirubin oxidation products (BOXes), are found in humans and animal models post subarachnoid hemorrhage. We have also proposed that BOXes may play a role in the pathogenesis and clinical complications post SAH. In this study we report on the direct toxicity effects of BOXes on rat brain.

METHODS

Identical volumes of either vehicle (normal saline) or BOXes (30 μl of a 20 μM solution) were applied above the dura through a cranial window of young (approximately 7-13 weeks) and aged (approximately 12-18 months) adult male Sprague Dawley rats (Charles River, Wilmington, MA, USA). To determine the extent of BOX-mediated injury, histology and immunocytochemistry were performed at 1, 2, 4, and 7 days post-surgical application of BOXes. We assessed the area of stress gene induction of HSP25/27 and HSP32. Immunohistochemistry was performed using standard avidin-biotin techniques. A monoclonal antibody to HSP25/27 (StressGen, Victoria, British Columbia, Canada), a monoclonal antibody to HSP32/HO-1 (StressGen), and a polyclonal HSP 32/HO-1 antibody were used for the immunocytochemistry.

RESULTS

A single dose of BOXes produced substantial increases in HSP25 and HO-1 in the aged rats at all early time points (≤4 days). After 7 days all groups were not significantly different than saline control. Young rats were resistant to BOXes effects compared to saline control with trends towards increased stress gene expression caused by BOXes that did not reach statistical significance.

CONCLUSION

We conclude from these studies that BOXes have direct effects on stress gene expression of the cortex post single dose application and that this can be seen for several days with apparent resolution at about 7 days. If BOXes are produced at similar levels in patients, the latency and duration of some SAH complications are consistent with these results.

The role of apolipoprotein e in the pathological events following subarachnoid hemorrhage: a review

Subarachnoid hemorrhage (SAH) strikes individuals with devastating neurological results. Traditional viewpoints do not explain all the differences that are usually found in clinical practice. The role of genetic predisposition in SAH has recently been investigated. Particular attention has been paid to the apolipoprotein E (apoE) genotype. APOE genotype is a major prognostic factor in patient outcome after spontaneous aneurysmal SAH. In patients with SAH, the expression of the apoE ε4 allele is associated with a higher risk of negative outcome and delayed ischemia. Evidence from experimental and clinical studies confirms that apoE plays an important role in the pathological events after SAH. This article reviews related research and surveys the links between the pathological events of SAH and apoE.

Advances in experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) remains to be a devastating disease with high mortality and morbidity. Two major areas are becoming the focus of the research interest of SAH: these are cerebral vasospasm (CVS) and early brain injury (EBI). This mini review will provide a broad summary of the major advances in experimental SAH during the last 3 years. Treatments interfering with nitric oxide (NO)- or endothelin-pathways continue to show antispasmotic effects in experimental SAH. HIF 1 may play both a detrimental and beneficial role in the setting of SAH, depending on its activation stage. Inflammation and oxidative stress contribute to the pathophysiology of both CVS and EBI. Apoptosis, a major component of EBI after SAH, also underlie the etiology of CVS. Since we recognize now that CVS and EBI are the two major contributors to the significant mortality and morbidity associated with SAH, ongoing research will continue to elucidate the underlying pathophysiological pathways and treatment strategies targeting both CVS and EBI may be more successful and improve outcome of patients with SAH.

Reversible cerebral vasospasm, multilobular intracerebral hemorrhages, and nonaneurysmal subarachnoid hemorrhage: review of possible interrelationships

"Reversible cerebral vasoconstriction syndrome" (RCVS) is a recently described entity that is mainly characterized by the association of severe ("thunderclap") headaches with or without additional neurological symptoms and diffuse, multifocal, segmental narrowings involving large and medium-sized cerebral arteries. By definition, angiographic abnormalities disappear within 3 months. The clinical course is usually benign, with a higher prevalence in young women. RCVS is idiopathic in the majority of the cases. However, recent papers have outlined the role of precipitating factors, including the use of vasoactive substances. Some patients, nevertheless, have a more severe clinical course with transient or permanent ischemic events. Hemorrhagic complications appear to have been underestimated. They are usually restricted to circumscribed cortical subarachnoid hemorrhage, in the absence of any ruptured cerebral aneurysm. This limited bleeding is unlikely at the origin of the diffuse vasoconstriction. The finding of an unruptured cerebral aneurysm in RCVS patients is probably incidental. An overlap is possible between RCVS and other syndromes such as posterior reversible encephalopathy syndrome. There is no standardized treatment regimen for RCVS patients. It appears rational to further investigate the efficacy and safety of the calcium-channel antagonist nimodipine.

The anti-inflammatory and neuroprotective effects of ghrelin in subarachnoid hemorrhage-induced oxidative brain damage in rats

To elucidate the putative neuroprotective effects of ghrelin in subarachnoid hemorrhage (SAH)-induced brain injury, Wistar albino rats (n = 54) were divided into sham-operated control, saline-treated SAH, and ghrelin-treated (10 microg/kg/d IP) SAH groups. The rats were injected with blood (0.3 mL) into the cisterna magna to induce SAH, and were sacrificed 48 h after the neurological examination scores were recorded. In plasma samples, neuron-specific enolase (NSE), S-100beta protein, TNF-alpha, and IL-1beta levels were evaluated, while forebrain tissue samples were taken for the measurement of malondialdehyde (MDA), glutathione (GSH), reactive oxygen species levels, myeloperoxidase (MPO), Na(+)-K(+)-ATPase activity, and DNA fragmentation ratio. Brain tissue samples containing the basilar arteries were obtained for histological examination, while cerebrum and cerebellum were removed for the measurement of blood-brain barrier (BBB) permeability and brain water content. The neurological scores were impaired at 48 h after SAH induction, and SAH caused significant decreases in brain GSH content and Na(+)-K(+)-ATPase activity, and increases in chemiluminescence, MDA levels, and MPO activity. Compared with the control group, the protein levels of NSE, S-100beta, TNF-alpha, and IL-1beta in plasma were also increased, while ghrelin treatment prevented all SAH-induced alterations observed both biochemically and histopathologically. The results demonstrate that ghrelin alleviates SAH-induced oxidative brain damage, and exerts neuroprotection by maintaining a balance in oxidant-antioxidant status, by inhibiting proinflammatory mediators, and preventing the depletion of endogenous antioxidants evoked by SAH.

Management of post-subarachnoid hemorrhage vasospasm

Permanent neurologic injury and death remain common outcomes following aneurysmal subarachnoid hemorrhage. Although many sophisticated techniques are evolving for securing intracranial aneurysms to prevent rebleeding, progress is lagging in the management of posthemorrhagic complications, particularly cerebral vasospasm. Vasospasm can be defined either angiographically, by visible reduction in arterial lumen diameters, or clinically, with signs of focal or regional cerebral ischemia. The relationship between angiographic and clinical vasospasm is not straightforward. The most important known risk factors for developing posthemorrhagic vasospasm include volume and distribution of subarachnoid blood, and no preventive measures have proven effective. Established treatment strategies for vasospasm include hyperdynamic therapy, angioplasty, and selective intra-arterial injection of vasodilators. The vasodilatory approach has been called into question by recent data suggesting that reduction of arterial luminal diameters may be due largely to a proliferative arteriopathy. Novel treatment strategies have focused on protecting the cerebrum, targeting components of the inflammatory cascade, and identifying genetic factors predisposing toward vasospasm, all of which may soon yield new treatment modalities.

Potential role of Ras in cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

Previous studies have demonstrated that mitogen-activated protein kinase (MAPK) is involved in the pathogenesis of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Ras, an upstream regulator of MAPK, may be activated following SAH. The aim of this study was to investigate the role of Ras in cerebral vasospasm in a rabbit model of SAH. We first investigated the time course of Ras and ERK1/2 activation in the basilar artery after SAH. Next, for the time point at which Ras was maximally activated, we assessed the effect of FTI-277 (a Ras farnesyltransferase inhibitor) on cerebral vasospasm. SAH was induced by injecting autologous blood into the cisterna magna on both day 0 and day 2. FTI-277 was injected into the cisterna magna every 24 hours, beginning 30 minutes after blood injection to the last day of the experiment. Elevated expression of Ras-GTP and phosphorylated ERK1/2 was detected in the basilar artery after SAH and expression peaked on day 3. FTI-277 administration resulted in lower Ras-GTP and phosphorylated ERK1/2 levels and markedly attenuated vasospasm in the basilar arteries relative to animals that did not receive FTI-277. Our results suggest that Ras protein is activated in the arterial wall after SAH and contributes to vasospasm development.

Inflammation and cerebral vasospasm after subarachnoid hemorrhage

Morbidity and mortality of patients with aneurysmal subarachnoid hemorrhage (aSAH) is significantly related to the development of chronic cerebral vasospasm. Despite extensive clinical and experimental research, the pathophysiology of the events that result in delayed arterial spasm is not fully understood. A review of the published literature on cerebral vasospasm that included but was not limited to all PubMed citations from 1951 to the present was performed. The findings suggest that leukocyte-endothelial cell interactions play a significant role in the pathophysiology of cerebral vasospasm and explain the clinical variability and time course of the disease. Experimental therapeutic targeting of the inflammatory response when timed correctly can prevent vasospasm, and supplementation of endothelial relaxation by nitric oxide-related therapies and other approaches could result in reversal of the arterial narrowing and improved outcomes in patients with aSAH.

Reversible cerebral vasoconstriction syndrome: an under-recognized clinical emergency

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by recurrent thunderclap headaches and reversible cerebral vasoconstrictions. RCVS is more common than previously thought and should be differentiated from aneurismal subarachnoid hemorrhage. RCVS can be spontaneous or evoked by pregnancy or exposure to vasoactive substances. Patients tend to be middle-aged women but pediatric patients have been seen. Up to 80% of sufferers have identifiable triggers. Thunderclap headaches tend to recur daily and last for a period of around 2 weeks, while the vasoconstrictions may last for months. About one-third of patients have blood pressure surges accompanying headache attacks. The potential complications of RCVS include posterior reversible encephalopathy syndrome, ischemic strokes over watershed zones, cortical subarachnoid hemorrhage and intracerebral hemorrhage. Magnetic resonance images including angiography and venography and lumbar punctures are the studies of choice, whereas catheter angiography should not be implemented routinely. Patients with a mean flow velocity of the middle cerebral artery greater than 120 cm/s shown by transcranial color-coded sonography have a greater risk of ischemic complications than those without. The pathophysiology of RCVS remains unknown; sympathetic hyperactivity may play a role. Open-label trials showed calcium channel blockers, such as nimodipine may be an effective treatment in prevention of thunderclap headache attacks. In severe cases, intra-arterial therapy may be considered. Most patients with RCVS recover without sequelae; however, relapse has been reported in a small proportion of patients.

A new approach to the treatment of cerebral vasospasm: the angiographic effects of tadalafil on experimental vasospasm

BACKGROUND

The pathogenesis of cerebral vasospasm is likely to be multifactorial. Strong evidence has indicated that decreasing levels of NO after SAH seem to be important. A PDE-V inhibitor, tadalafil, theoretically increases NO levels. Our study investigated the vasodilatory efficacy of tadalafil on the cerebral arteries with measurement of basilar artery diameters on angiography.

METHODS

We used 42 male Wistar-Albino rats to test our hypothesis. They were assigned randomly into the following seven groups: group 1: control (only saline), group 2: SAH only (killed on day 2), group 3: SAH + tadalafil (killed on day 2), group 4: SAH only (killed on day 4), group 5: SAH + tadalafil (killed on day 4), group 6: saline + tadalafil (killed on day 2) and group 7: saline + tadalafil (killed on day 4). The three different parts of basilar artery diameters were measured angiographically.

RESULTS

There were statistically significant differences between the SAH and SAH groups treated with tadalafil at days 2 and 4. Comparison between control and tadalafil groups showed no significant differences. This result indicated that tadalafil has a vasodilatory effect on vasoconstricted arteries, but no effect on normal basilar arteries.

CONCLUSION

Our study results showed that tadalafil has a vasodilatory effect on both acute and chronic periods of cerebral vasospasm. We also concluded that cerebral angiography can be used safely for investigation of cerebral vasospasm in animal studies.

Tirilazad for aneurysmal subarachnoid haemorrhage

BACKGROUND

Delayed cerebral ischaemia is a significant contributor to poor outcome (death or disability) in patients with aneurysmal subarachnoid haemorrhage (SAH). Tirilazad is considered to have neuroprotective properties in animal models of acute cerebral ischaemia.

OBJECTIVES

To assess the efficacy and safety of tirilazad in patients with aneurysmal SAH.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched October 2009); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2009); MEDLINE (1966 to October 2009); EMBASE (1980 to October 2009); and the Stroke Trials Directory, the National Center for Complementary and Alternative Medicine, and the National Institute of Health Clinical Trials Database (searched October 2009). We handsearched 10 Chinese journals, searched the reference lists of relevant publications, and contacted the manufacturers of tirilazad.

SELECTION CRITERIA

Randomised trials of tirilazad started within four days of SAH onset, compared with placebo or open control in patients with aneurysmal SAH documented by angiography and computerised tomography (CT) scan or cerebrospinal fluid examination, or both.

DATA COLLECTION AND ANALYSIS

We extracted data relating to case fatality, poor outcome (death, vegetative state, or severe disability), delayed cerebral ischaemia (or symptomatic vasospasm), cerebral infarction and adverse events of treatments. We pooled the data using the Peto fixed-effect method for dichotomous data.

MAIN RESULTS

We included five double-blind, placebo-controlled trials involving 3821 patients; there was no significant heterogeneity. Oral or intravenous nimodipine was used routinely as a background treatment in both groups in all trials. There was no significant difference between the two groups at the end of follow up for the primary outcome, death (odds ratio (OR) 0.89, 95% confidence interval (CI) 0.74 to 1.06), or in poor outcome (death, vegetative state or severe disability) (OR 1.04, 95% CI 0.90 to 1.21). During the treatment period, fewer patients developed delayed cerebral ischaemia in the tirilazad group than in the control group (OR 0.80, 95% CI 0.69 to 0.93). Subgroup analyses did not demonstrate any significant difference in effects of tirilazad on clinical outcomes. Leukocytosis and prolongation of Q-T interval occurred significantly more frequently in the treatment group in only one trial evaluating tirilazad at high dose. There was no significant difference in infusion site disorders or other laboratory parameters between the two groups.

AUTHORS' CONCLUSIONS

There is no evidence that tirilazad, in addition to nimodipine, reduces mortality or improves poor outcome in patients with aneurysmal SAH.

Therapeutic approaches to cerebral vasospasm complicating ruptured aneurysm

Cerebral vasospasm is a serious complication of ruptured aneurysm. In order to avoid short- and long-term effects of cerebral vasospasm, and as there is no single or optimal treatment modality employed, we have instituted a protocol for the prevention and treatment of vasospasm in patients suffering aneurysmal sub-arachnoid hemorrhage (SAH). We then reviewed the effectiveness of this protocol in reducing the mortality and morbidity rate in our institution. In this study we present a retrospective analysis of 52 cases. Between March 2004 and December 2008 52 patients were admitted to our service with aneurysmal SAH. All patients commenced nimodipine, magnesium sulphate (MgSO₄) and triple H therapy. Patients with significant reduction in conscious level were intubated, ventilated and sedated. Intracranial pressure (ICP) monitoring was used for intubated patients. Sodium thiopental coma was induced for patients with refractory high ICP; angiography was performed for diagnosis and treatment. Balloon angioplasty was performed if considered necessary. Using this protocol, only 13 patients (25%) developed clinical vasospasm. Ten of them were given barbiturates to induce coma. Three patients underwent transluminal balloon angioplasty. Four out of 52 patients (7.7%) died from severe vasospasm, 3 patients (5.8%) became severely disabled, and 39 patients (75%) were discharged in a condition considered as either normal or near to their pre-hemorrhage status. Our results confirm that the aforementioned protocol for treatment of cerebral vasospasm is effective and can be used safely.

Role of inflammation (leukocyte-endothelial cell interactions) in vasospasm after subarachnoid hemorrhage

BACKGROUND

Delayed vasospasm is the leading cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage (aSAH). This phenomenon was first described more than 50 years ago, but only recently has the role of inflammation in this condition become better understood.

METHODS

The literature was reviewed for studies on delayed vasospasm and inflammation.

RESULTS

There is increasing evidence that inflammation and, more specifically, leukocyte-endothelial cell interactions play a critical role in the pathogenesis of vasospasm after aSAH, as well as in other conditions including meningitis and traumatic brain injury. Although earlier clinical observations and indirect experimental evidence suggested an association between inflammation and chronic vasospasm, recently direct molecular evidence demonstrates the central role of leukocyte-endothelial cell interactions in the development of chronic vasospasm. This evidence shows in both clinical and experimental studies that cell adhesion molecules (CAMs) are up-regulated in the perivasospasm period. Moreover, the use of monoclonal antibodies against these CAMs, as well as drugs that decrease the expression of CAMs, decreases vasospasm in experimental studies. It also appears that certain individuals are genetically predisposed to a severe inflammatory response after aSAH based on their haptoglobin genotype, which in turn predisposes them to develop clinically symptomatic vasospasm.

CONCLUSION

Based on this evidence, leukocyte-endothelial cell interactions appear to be the root cause of chronic vasospasm. This hypothesis predicts many surprising features of vasospasm and explains apparently unrelated phenomena observed in aSAH patients. Therapies aimed at preventing inflammation may prevent and/or reverse arterial narrowing in patients with aSAH and result in improved outcomes.

Serum and cerebrospinal fluid C-reactive protein levels as predictors of vasospasm in aneurysmal subarachnoid hemorrhage. Clinical article

OBJECT

Cerebral vasospasm is a common and potentially devastating complication of aneurysmal subarachnoid hemorrhage (aSAH). Inflammatory processes seem to play a major role in the pathogenesis of vasospasm. The C-reactive protein (CRP) constitutes a highly sensitive inflammatory marker. The association of elevated systemic CRP and coronary vasospasm has been well established. Additionally, elevation of the serum CRP levels has been demonstrated in patients with aSAH. The purpose of the current study was to evaluate the possible relationship between elevated CRP levels in the serum and CSF and the development of vasospasm in patients with aSAH.

METHODS

A total of 41 adult patients in whom aSAH was diagnosed were included in the study. Their demographics, the admitting Glasgow Coma Scale (GCS) score, Hunt and Hess grade, Fisher grade, CT scans, digital subtraction angiography studies, and daily neurological examinations were recorded. Serial serum and CSF CRP measurements were obtained on Days 0, 1, 2, 3, 5, 7, and 9. All patients underwent either surgical or endovascular treatment within 48 hours of their admission. The outcome was evaluated using the Glasgow Outcome Scale and the modified Rankin Scale.

RESULTS

The CRP levels in serum and CSF peaked on the 3rd postadmission day, and the CRP levels in CSF were always higher than the serum levels. Patients with lower admission GCS scores and higher Hunt and Hess and Fisher grades had statistically significantly higher levels of CRP in serum and CSF. Patients with angiographic vasospasm had higher CRP measurements in serum and CSF, in a statistically significant fashion (p < 0.0001). Additionally, patients with higher CRP levels in serum and CSF had less favorable outcome in this cohort.

CONCLUSIONS

Patients with aSAH who had high Hunt and Hess and Fisher grades and low GCS scores showed elevated CRP levels in their CSF and serum. Furthermore, patients developing angiographically proven vasospasm demonstrated significantly elevated CRP levels in serum and CSF, and increased CRP measurements were strongly associated with poor clinical outcome in this cohort.

Significance of apolipoprotein E in subarachnoid hemorrhage: neuronal injury, repair, and therapeutic perspectives--a review

Subarachnoid hemorrhage (SAH) strikes individuals at a young age with devastating neurologic consequences. Classic formulations that correlate complications and outcome with clinical variables do not explain all the heterogeneity that is usually found in clinical practice. The role of genetic predisposition has recently been investigated. Particular attention has been paid to the apolipoprotein E (APOE) genotype that encodes for a polymorphic protein existing as 3 isoforms (apoE2, apoE3, apoE4), products of alleles E2, E3, and E4 at a single gene locus. ApoE is produced by astrocytes and exerts complex neuroprotective functions that make it a hub of the biochemical network of SAH. The neuroprotective effectiveness of the apoE4 isoform is reduced with respect to the others and this has made the E4 allele a risk factor candidate. Recently published observational studies and meta-analyses suggested that the APOE genotype may strongly improve the usual predictive model with the possibility of optimizing clinical decisions according to the individual's needs. Furthermore, the clinical results, together with new biological insights, suggest that SAH may be a possible candidate for the ongoing research on apoE-based neuroprotective therapy. This article reviews the clinical studies, analyzes their methodology, and surveys the biological links between the physiopathology of SAH and apoE and the possible prospects.

Endothelial nitric oxide synthase tagging single nucleotide polymorphisms and recovery from aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a hemorrhagic stroke subtype with a poor recovery profile. Cerebral vasospasm (CV), a narrowing of the cerebral vasculature, significantly contributes to the poor recovery profile. Variation in the endothelial nitric oxide (NO) synthase (eNOS) gene has been implicated in CV and outcome after SAH. The purpose of this project was to explore the potential association between three eNOS tagging single nucleotide polymorphisms (SNPs) and recovery from SAH. We included 195 participants with a diagnosis of SAH and DNA and 6-month outcome data available but without preexisting neurologic disease/deficit. Genotyping was performed using an ABI Prism 7000 Sequence Detection System and TaqMan assays. CV was verified by cerebral angiogram independently read by a neurosurgeon on 118 participants. Modified Rankin Scores (MRS) and Glasgow Outcome Scale (GOS) scores were collected 6 months posthemorrhage. Data were analyzed using descriptive statistics, analysis of variance (ANOVA) and chi-square analysis as appropriate. The sample was primarily female (n=147; 75.4%) and White (n=178; 91.3%) with a mean age of 54.6 years. Of the participants with CV data, 56 (47.5%) developed CV within 14 days of SAH. None of the SNPs individually were associated with CV presence; however, a combination of the three variant SNPs was significantly associated with CV (p=.017). Only one SNP (rs1799983, variant allele) was associated with worse 6-month GOS scores (p<.001) and MRS (p<.001). These data indicate that the eNOS gene plays a role in the response to SAH, which may be explained by an influence on CV.

Cerebral vasospasm following subarachnoid hemorrhage: time for a new world of thought

OBJECTIVE

Delayed cerebral vasospasm has long been recognized as an important cause of poor outcome after an otherwise successful treatment of a ruptured intracranial aneurysm, but it remains a pathophysiological enigma despite intensive research for more than half a century.

METHOD

Summarized in this review are highlights of research from North America, Europe and Asia reflecting recent advances in the understanding of delayed ischemic deficit.

RESULT

It will focus on current accepted mechanisms and on new frontiers in vasospasm research.

CONCLUSION

A key issue is the recognition of events other than arterial narrowing such as early brain injury and cortical spreading depression and of their contribution to overall mortality and morbidity.

Pathogenesis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage: putative mechanisms and novel approaches

Cerebral vasospasm is a potentially incapacitating or lethal complication in patients with aneurysmal subarachnoid hemorrhage (SAH). The development of effective preventative and therapeutic interventions has been largely hindered by the fact that the underlying pathogenic mechanisms of cerebral vasospasm remain poorly understood. However, intensive research during the last 3 decades has identified certain mechanisms that possibly play a role in its development. Experimental data suggest that calcium-dependent and -independent vasoconstriction is taking place during vasospasm. It appears that the breakdown products of blood in the subarachnoid space are involved, through direct and/or indirect pathways, in the development of vasospasm after SAH. Free radicals reactions, an imbalance between vasoconstrictor and vasodilator substances (endothelium derived substances, e.g., nitric oxide, endothelin; arachidonic acid metabolites, e.g., prostaglandins, prostacyclin), inflammatory processes, an upheaval of neuronal mechanisms that regulate vascular tone, endothelial proliferation, and apoptosis have all been put forward as causative and/or pathogenic factors. Translational research in the field of vasospasm has traditionally aimed to identify agents/interventions in order to block the cascades initiated after SAH. The combination of novel approaches such as cerebral microdialysis, magnetic resonance spectroscopy, proteomics, and lipidomics could serve a dual purpose: elucidating the complex pathobiochemistry of vasospasm and providing clinicians with tools for early detection of this feared complication. The purpose of this Mini-Review is to provide an overview of the pathogenesis of cerebral vasospasm and of novel approaches used in basic and translational research.

Comparison of contractile mechanisms of sphingosylphosphorylcholine and sphingosine-1-phosphate in rabbit coronary artery

AIMS

Although stimulation with sphingosylphosphorylcholine (SPC) or sphingosine-1-phosphate (S1P) generally leads to similar vascular responses, the contractile patterns and their underlying signalling mechanisms are often distinct. We investigated the different reliance upon Ca2+-dependent and Ca2+-sensitizing mechanisms of constriction in response to SPC or S1P in coronary arteries.

METHODS AND RESULTS

Contractile responses, changes in [Ca2+]i, and phosphorylation of myosin light chain phosphatase-targeting subunit (MYPT1) were measured. SPC induced a concentration-dependent sustained contraction. S1P evoked a rapid rise in force (initial transient), which was followed by a secondary sustained force. In the absence of extracellular Ca2+, the concentration dependency of constriction to SPC was shifted to the right, but with no change in maximum force, whereas S1P-induced contraction was significantly blunted. Cyclopiazonic acid (CPA) significantly decreased the initial transient force induced by S1P. In isolated single cells, S1P markedly increased [Ca2+]i, whereas only a modest elevation was noted with SPC. The S1P-induced elevation of [Ca2+]i was abolished by pre-treatment with CPA and was significantly reduced in the absence of extracellular Ca2+. In beta-escin-permeabilized strips, SPC augmented pCa 6.3-induced force; this was significantly inhibited by fasudil hydrochloride. S1P induced little or no augmentation of pCa 6.3-induced force. In intact arteries, SPC-induced contraction was completely inhibited by fasudil hydrochloride. Fasudil hydrochloride had no effect on the initial transient force induced by S1P but significantly inhibited the secondary sustained force. SPC induced a several-fold increase in Thr696 and Thr853 phosphorylation of MYPT1, but S1P did not affect phosphorylation of MYPT1.

CONCLUSION

Our results suggest that constriction of coronary arteries in response to the bioactive lipid S1P or SPC occurs by distinct signalling pathways. Activation of the RhoA/RhoA-associated kinase pathway and subsequent phosphorylation of MYPT1 play a key role in SPC-induced coronary contraction, whereas elevation of [Ca2+]i is crucial for S1P-induced coronary constriction.

A review of medical treatments of cerebral vasospasm

We review the literature on the established perioperative therapies for cerebral vasospasm (CV) following aneurysmal subarachnoid hemorrhage (aSAH). Despite aSAH treatment advances, CV continues to be a significant source of post-SAH morbidity and mortality. In fact, CV has been correlated with a 7.5- to three-fold increase in mortality in the first 2 weeks after SAH. As new treatment modalities show promise in animal models and early clinical trials, greater efforts are needed to test these new approaches. Few evidence-based indications for the treatment of vasospasm currently exist. Large-scale randomized clinical trials are needed to determine whether therapies such as magnesium, statins, nitric oxide modulators, endothelin antagonists and others will become standard of care in the prevention and/or treatment of CV.

Clazosentan: an endothelin receptor antagonist for treatment of vasospasm after subarachnoid hemorrhage

Clazosentan (Ro 61-1790, VML-588 or AXV-034) is under study in clinical trials for the treatment of patients with aneurysmal subarachnoid hemorrhage (SAH) by Actelion Pharmaceuticals. It is a synthetic endothelin (ET) A receptor antagonist that decreases and reverses cerebral vasospasm after experimental SAH. Remarkable dose-dependent effects were observed on angiographic vasospasm in the CONSCIOUS-1 human clinical trial, supporting proceeding with a Phase III clinical trial. This study (CONSCIOUS-2) will enroll approximately 765 patients randomized 2:1 to clazosentan 5 mg/h intravenously or placebo. All patients will undergo neurosurgical aneurysm clipping and outcome will be assessed primarily based on mortality and vasospasm-related morbidity.

Effects of raloxifene on cerebral vasospasm after experimental Subarachnoid Hemorrhage in rabbits

BACKGROUND

The aim of this study was to investigate the ability of a SERM, RLX, to prevent vasospasm in a rabbit model of SAH.

METHODS

Thirty-four New Zealand white rabbits were allocated into 3 groups randomly. Subarachnoid hemorrhage was induced by injecting autologous blood into the cisterna magna. The treatment groups were as follows: (1) sham operated (no SAH [n = 12]), (2) SAH only (n = 12), and (3) SAH plus RLX (n = 10). Basilar artery lumen areas and arterial wall thickness were measured to assess vasospams in all groups.

RESULTS

There was a statistically significant difference between the mean basilar artery cross-sectional areas and the mean arterial wall thickness measurements of the control and SAH-only groups (P < .05). The difference between the mean basilar artery cross-sectional areas and the mean arterial wall thickness measurements in the RLX-treated group was statistically significant (P < .05). The difference between the SAH group and the SAH + RLX group was also statistically significant (P < .05).

CONCLUSIONS

These findings demonstrate that RLX has marked vasodilatatory effect in an experimental model of SAH in rabbits. This observation may have clinical implications suggesting that this SERM drug could be used as possible anti-vasospastic agent in patients without major adverse effects.

CT angiography and perfusion imaging in patients with subarachnoid hemorrhage: correlation of vasospasm to perfusion abnormality

INTRODUCTION

We retrospectively evaluated computed tomography angiography (CTA) and perfusion imaging (CTP) of patients with aneurysmal subarachnoid hemorrhage (SAH) for any correlation between degree of vasospasm and perfusion deficit.

MATERIALS AND METHODS

Sequentially performed CTP and CTA of 41 patients at least at the third day of postbleeding were reviewed for vasospasm and perfusion deficit throughout the anterior and middle cerebral arteries and corresponding territories. Vasospasm was noted comparing the contralateral normal ones or extradural components of the vessel itself and graded to negative, mild, moderate, and severe as luminal narrowing none, <25%, between 25% and 50%, and >or=50%, respectively. CTP abnormality was noted using cerebral blood flow and volume and mean transit time maps.

RESULTS

Of 41 patients, 20 had no vasospasm; 15 had mild to moderate and six had severe vasospasm. Three of 20 patients with no vasospasm (15%), four of 15 patients with mild to moderate vasospasm (26%), and five of six patients with severe vasospasm (83%) had perfusion abnormality. Perfusion abnormalities noted were ischemia, infarction, and hyperperfusion. Perfusion abnormality without vasospasm was observed in the watershed areas and adjacent to sulcal clots.

CONCLUSION

In SAH patients, if there is a macrovascular vasospasm with luminal narrowing >or=50%, there is a high likelihood (83%) of perfusion abnormality in the territory of the vasospastic vessel. There may also be perfusion abnormality without macrovascular vasospasm in the watershed areas or in the vicinity of sulcal clots.

Cellular basis of vasospasm: role of small diameter arteries and voltage-dependent Ca2+ channels

Constriction of small (100-200 microm) diameter cerebral arteries in response to increased intravascular pressure plays an important role in the regulation of cerebral blood flow. In arteries from healthy animals, these pressure-induced constrictions arise from depolarization of arterial smooth muscle leading to enhanced activity of L-type voltage-dependent calcium channels. Recently, we have observed that pressure-induced constrictions are greatly enhanced in cerebral arteries obtained from a rabbit model of subarachnoid hemorrhage (SAH) due to the emergence of R-type voltage-dependent calcium channels in arterial myocytes. Enhanced pressure-induced constrictions and the resulting decrease in cerebral blood may contribute to the development of neurological deficits in SAH patients following cerebral aneurysm rupture. This work supports the concept that small diameter arteries represent important targets for current treatment modalities (e.g. Hypertensive, Hypervolemic, Hemodilution "triple H" therapy) used in SAH patients. Further, we propose targeting R-type calcium channels, encoded by the gene Ca(v)2.3, as a novel therapeutic strategy in the treatment of SAH-induced cerebral vasospasm.

Gene expression in a canine basilar artery vasospasm model: a genome-wide network-based analysis

To investigate the changes of gene expression on the cerebral vasospasm after subarachnoid hemorrhage, we used genome-wide microarray for a canine double-hemorrhage model and analyzed the data by using a network-based analysis. Six dogs were assigned to two groups of three animals: control and hemorrhage. The effects were assessed by the changes in gene expressions in the artery 7 days after the first blood injection. Among 23,914 genes, 447 and 66 genes were up-regulated more than two- and fivefold, respectively, and 332 and 25 genes were down-regulated more than two- and fivefold, respectively. According to gene ontology, genes related to cell communication (P = 5.28E-10), host–pathogen interaction (7.65E-8), and defense–immunity protein activity (0.000183) were significantly overrepresented. The top high-level function for the merged network derived from the network-based analysis was cell signaling, revealing that the subgroup that regulates the quantity of Ca²⁺ to have the strongest association significance (P = 4.75E-16). Canine microarray analysis followed by gene ontology profiling and connectivity analysis identified several functional groups and individual genes responding to cerebral vasospasm. Ca²⁺ regulation may play a key role in these gene expression changes and may be involved in the pathogenesis of cerebral vasospasm.

Cerebral hemorrhage and vasospasm in a child with congenital heart disease

INTRODUCTION

Intracerebral hemorrhages are relatively rare events in children and cerebral vasospasm after such hemorrhages is even more unusual. Children with structural congenital heart disease are particularly at risk for both thrombotic and embolic events but not to isolated hemorrhages.

DISCUSSION

We report a case of cerebral vasospasm in a child with structural congenital heart disease after a cerebral hemorrhage.

CONCLUSION

This case illustrates that this rare occurrence must be swiftly recognized and treated in order to maximize clinical outcome.