Cerebrovascular inflammation following subarachnoid hemorrhage

Relevance of cerebral interleukin-6 after aneurysmal subarachnoid hemorrhage

BACKGROUND

This study examines the inflammatory response via interleukin-6 (IL-6) in aneurysmal subarachnoid hemorrhage (aSAH) patients and its association with their clinical course (occurrence of acute focal neurological deficits, AFND; and delayed cerebral ischemia, DCI).

METHODS

A total of 38 consecutive aSAH patients were studied prospectively within 14 days after admission and classified as asymptomatic (n = 9; WFNS grade 1 (1-2), median and quartiles) and symptomatic (n = 29; WFNS grade 4 (2-5)); the latter presenting with AFND (n = 13), DCI (n = 10) or both (n = 6). Levels of pro-inflammatory cytokine IL-6 were determined in cerebral extracellular fluid (ECF, using cerebral microdialysis), cerebrospinal fluid (CSF) and plasma for 10 days after aSAH. Additionally, C-reactive protein (CRP) levels were measured in plasma.

RESULTS

High IL-6 levels in CSF, ECF and plasma were found in all patients, reflecting a pronounced local inflammatory response after aSAH, followed only in symptomatic patients by a delayed systemic inflammation (CRP P < 0.025, days 7-9 after aSAH). In all compartments, IL-6 levels appeared to be higher in symptomatic patients, accompanied also by a higher ECF lactate-pyruvate ratio (P = 0.04). Cerebral, but not plasma IL-6, levels were indicative of the development of DCI in symptomatic patients (ECF P = 0.003; CSF P = 0.001).

CONCLUSIONS

A pronounced initial cerebral inflammatory state was observed in patients of all WFNS grades, suggesting that IL-6 elevations are not necessarily detrimental. Cerebral, but not plasma IL-6, levels were predictive of the development of delayed ischemic deficits in symptomatic patients, suggesting that CSF or ECF are the best sampling media for future studies.

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.

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.

Immunological response in early brain injury after SAH

This study summarized the role of inflammation in the early brain injury after subarachnoid hemorrhage. Elevation of cytokines, activation of MMPs and phosphorylation of MAPK contributes to neuronal apoptosis and brain edema. Anti-inflammation may be potential strategy for the prevention and suppression of early brain injury after subarachnoid hemorrhage.

The relationship between IL-6 in CSF and occurrence of vasospasm after subarachnoid hemorrhage

BACKGROUND

It is hypothesized that inflammatory response after subarachnoid hemorrhage (SAH) may play a relevant role in the development and maintenance of vasospasm. This research investigated the correlation between IL-6 in cerebrospinal fluid (CSF) after SAH and the occurrence of vasospasm.

METHODS

We analyzed both daily clinical manifestation and laboratory data of CSF in 46 patients who suffered from intracranial aneurismal subarachnoid hemorrhage during a period of 14 days, studied the relationship between the development of vasospasm and the quantities of the inflammatory factor, revealing potential power of IL-6 for predicting vasospasm detected by transcranial doppler (TCD).

RESULTS

The incidence of vasospasm developed in 43.5% of the patients, with a mean onset of 6.1±4.6 days after intracranial aneurysm treatment. Patients with vasospasm demonstrated statistically significant higher median values of IL-6CSF on Day 1, 2, 3, 5 and 7 (P<0.05). The cut-off value is settled in 400 pg/ml on Day 3 after treatment. On the other hand, gender, Hunt & Hess scale (H&H) and Fisher scale of CT after SAH were proved to be the correlation factor with vasospasm.

CONCLUSION

IL-6CSF seems to be a reliable early marker for predicting vasospasm after subarachnoid hemorrhage on Days 3 after treatment before clinical onset.

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.

Intracranial hemorrhage: mechanisms of secondary brain injury

ICH is a disease with high rates of mortality and morbidity, with a substantial public health impact. Spontaneous ICH (sICH) has been extensively studied, and a large body of data has been accumulated on its pathophysiology. However, the literature on traumatic ICH (tICH) is limited, and further investigations of this important topic are needed. This review will highlight some of the cellular pathways in ICH with an emphasis on the mechanisms of secondary injury due to heme toxicity and to events in the coagulation process that are common to both sICH and tICH.

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.

Platelet-derived growth factor-induced severe and chronic vasoconstriction of cerebral arteries: proposed growth factor explanation of cerebral vasospasm

OBJECTIVE

After subarachnoid hemorrhage (SAH), platelet-derived growth factor-BB (PDGF-BB) is secreted in and around the cerebral arteries. To clarify the role of PDGF-BB in the development of vasospasm after SAH, we determined whether PDGF-BB alone can cause long-lasting vasoconstriction of a severity similar to that of vasospasm. In addition, the anti-vasospastic effect of trapidil, an antagonist of PDGF-BB function, was investigated.

METHODS

We infused recombinant PDGF-BB (10 microg/mL saline as the vehicle) (n = 14) into the subarachnoid space of rabbits and analyzed alterations in the caliber of the basilar artery using repeated angiography. To study the role of PDGF-BB on the development of vasospasm, trapidil was administered continuously starting 1 hour after SAH, on day 0 (0.63-1.25 mg/kg /h or vehicle) for 47 hours (n = 24), or after the full development of cerebral vasospasm on day 2 (3.0 mg/kg/h or vehicle) for 0.5 hours (n = 17), and alterations in the caliber of the basilar artery were monitored.

RESULTS

PDGF-BB caused long-lasting vasoconstriction, with maximum constriction of 56% (P < .001) of the control value (= 100%) on day 2, resembling vasospasm seen after SAH. Prolonged administration of intravenous trapidil, starting soon after SAH, prevented the development of vasospasm in a dose-dependent manner (P < .05, .01, or .001). Intravenous or intra-arterial administration of trapidil significantly dilated vasospasm (P < .01) on day 2, at least transiently.

CONCLUSION

PDGF-BB, a growth factor synthesized in the subarachnoid space after SAH, can cause severe and long-lasting vasoconstriction. Significant prevention and resolution of vasospasm can be achieved by the PDGF-BB antagonist trapidil. We propose that excessive production of PDGF-BB, essentially aiming to repair injured arteries, causes cerebral vasospasm. Although the half-life of trapidil in serum may be shorter than that of PDGFG-BB-derived spasmogenic signaling, trapidil is a candidate drug for constructing a new therapeutic modality for preventing and resolving vasospasm.

Randomized, double-blind, placebo-controlled, pilot trial of high-dose methylprednisolone in aneurysmal subarachnoid hemorrhage

OBJECT

The object of this study was to determine the efficacy of methylprednisolone in reducing symptomatic vasospasm and poor outcomes after subarachnoid hemorrhage (SAH).

METHODS

Ninety-five patients with proven SAH were recruited into a double-blind, placebo-controlled, randomized trial. Starting within 6 hours after angiographic diagnosis of aneurysm rupture, placebo or methylprednisolone, 16 mg/kg, was administered intravenously every day for 3 days to 46 and 49 patients, respectively. Deterioration, defined as development of a focal sign or decrease of more than 1 point on the Glasgow Coma Scale for more than 6 hours, was investigated by using clinical criteria and transcranial Doppler ultrasonography, cerebral angiography, or CT when appropriate. The end points were incidence of symptomatic vasospasm (delayed ischemic neurological deficits associated with angiographic arterial narrowing or accelerated flow on Doppler ultrasonography, or both) and outcome 1 year after entry into the study according to a simplified Rankin scale (Functional Outcome Scale [FOS]) in living patients and the Glasgow Outcome Scale in all patients included.

RESULTS

All episodes of deterioration and all living patients with a 1-year outcome were assessed by a review committee. In patients treated with methylprednisolone, the incidence of symptomatic vasospasm was 26.5% compared with 26.0% in those given placebo. Poor outcomes according to FOS were significantly reduced in the Methylprednisolone Group at 1 year of follow-up; the risk difference was 19.3% (95% CI 0.5-37.9%). The outcome was poor in 15% (6/40) of patients in the Methylprednisolone Group versus 34% (13/38) in the Placebo Group.

CONCLUSIONS

A safe and simple treatment with methylprednisolone did not reduce the incidence of symptomatic vasospasm but improved ability and functional outcome at 1 year after SAH.

Elucidating novel mechanisms of brain injury following subarachnoid hemorrhage: an emerging role for neuroproteomics

Subarachnoid hemorrhage (SAH) is a devastating neurological injury associated with significant patient morbidity and death. Since the first demonstration of cerebral vasospasm nearly 60 years ago, the preponderance of research has focused on strategies to limit arterial narrowing and delayed cerebral ischemia following SAH. However, recent clinical and preclinical data indicate a functional dissociation between cerebral vasospasm and neurological outcome, signaling the need for a paradigm shift in the study of brain injury following SAH. Early brain injury may contribute to poor outcome and early death following SAH. However, elucidation of the complex cellular mechanisms underlying early brain injury remains a major challenge. The advent of modern neuroproteomics has rapidly advanced scientific discovery by allowing proteome-wide screening in an objective, nonbiased manner, providing novel mechanisms of brain physiology and injury. In the context of neurosurgery, proteomic analysis of patient-derived CSF will permit the identification of biomarkers and/or novel drug targets that may not be intuitively linked with any particular disease. In the present report, the authors discuss the utility of neuroproteomics with a focus on the roles for this technology in understanding SAH. The authors also provide data from our laboratory that identifies high-mobility group box protein-1 as a potential biomarker of neurological outcome following SAH in humans.

Role of interleukin-1beta in early brain injury after subarachnoid hemorrhage in mice

BACKGROUND AND PURPOSE

The role of interleukin (IL)-1beta remains unknown in early brain injury (EBI) after subarachnoid hemorrhage (SAH), although IL-1beta has been repeatedly reported to increase in the brain and cerebrospinal fluid. The aim of this study is to examine the effects of IL-1beta inactivation on EBI after SAH in mice.

METHODS

The endovascular perforation model of SAH was produced and 112 mice were assigned to sham, SAH+ vehicle, and SAH+ N-Ac-Tyr-Val-Ala-Asp-chloromethyl ketone (Ac-YVAD-CMK, 6 and 10 mg/kg) groups. Ac-YVAD-CMK, a selective inhibitor of IL-1beta converting enzyme, or vehicle was administered intraperitoneally 1 hour post-SAH. EBI was assessed in terms of mortality within 24 hours, neurological scores, brain water content at 24 and 72 hours, Evans blue dye extravasation and Western blot for IL-1beta, c-Jun N-Terminal kinase (JNK), matrix metalloproteinase (MMP)-9, and zonula occludens (ZO)-1 at 24 hours after SAH.

RESULTS

High-dose (10 mg/kg) but not low-dose (6 mg/kg) treatment group significantly improved neurological scores, mortality, brain water content, and Evans blue dye extravasation compared with the vehicle group. Although both dosages of Ac-YVAD-CMK attenuated the mature IL-1beta induction, only high-dose treatment group significantly inhibited the phosphorylation of JNK, MMP-9 induction, and ZO-1 degradation.

CONCLUSIONS

IL-1beta activation may play an important role in the pathogenesis of EBI after SAH. The neurovascular protection of Ac-YVAD-CMK may be provided by the inhibition of JNK-mediated MMP-9 induction and the consequent preservation of tight junction protein ZO-1.

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.

Thrombin inhibition by argatroban ameliorates early brain injury and improves neurological outcomes after experimental subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

We investigated the role of thrombin in early brain injury after subarachnoid hemorrhage (SAH).

METHODS

The standard intravascular perforation model was used to produce experimental SAH in Sprague Dawley rats. Low-dose (0.3 mg/h) and high-dose (0.9 mg/h) argatroban, a direct thrombin inhibitor, were evaluated for effects on brain edema, blood-brain barrier (BBB) disruption, apoptotic cell death, inflammatory marker, and neurological outcomes after SAH.

RESULTS

Both doses of argatroban attenuated BBB disruption; however, only high-dose was effective in lowering edema in all brain regions, reducing cell death, and inflammatory marker expression, and improving neurological outcomes.

CONCLUSIONS

Thrombin inhibition by argatroban improves neurological outcomes and provides neuroprotection against acute events after SAH such as BBB disruption, brain edema, and cell death.

Relationship between sympathetic nervous activity and inflammatory response after subarachnoid hemorrhage in a perforating canine model

The objective of the present study was to evaluate the correlation between sympathetic nerve activation and inflammatory response in the acute stage of subarachnoid hemorrhage (SAH) in a canine perforating model. SAH was induced by perforation of the basilar artery with the use of a microcatheter via the femoral artery in 20 mongrel dogs. Hemodynamic parameters and intracranial pressure were recorded, and blood sample for C3a, C5b-9, IL-6, IL-8 and noradrenaline kinetic determination were measured at 0, 5, 15, 30, 60, 120, and 180 min after SAH. Noradrenaline (pg/mL) increased abruptly from 104+/-59 to 2010+/-918 at 5 min after SAH. C3a and C5b-9 reached peak values at 15 min and IL-6 and IL-8 reached peak values at 30 min after SAH, respectively. The peak values of C3a and C5b-9 correlated positively with the peak value of noradrenaline (r=0.743 and r=0.753, respectively). The peak values of IL-6 and IL-8 also correlated positively with the peak values of noradrenaline (r=0.603 and r=0.681, respectively).These results suggest that a pronounced activation of the sympathetic nervous system and the inflammatory response occurs in acute stage of SAH. Significant association between the rate of spillover of norepinephrine to plasma and the plasma levels of inflammatory markers indicates that the two processes, sympathetic activation and immune response are quantitatively linked in early stage after SAH. The exact mechanisms underlying this phenomenon deserved further investigations.

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.

Glibenclamide reduces inflammation, vasogenic edema, and caspase-3 activation after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) causes secondary brain injury due to vasospasm and inflammation. Here, we studied a rat model of mild-to-moderate SAH intended to minimize ischemia/hypoxia to examine the role of sulfonylurea receptor 1 (SUR1) in the inflammatory response induced by SAH. mRNA for Abcc8, which encodes SUR1, and SUR1 protein were abundantly upregulated in cortex adjacent to SAH, where tumor-necrosis factor-alpha (TNFalpha) and nuclear factor (NF)kappaB signaling were prominent. In vitro experiments confirmed that Abcc8 transcription is stimulated by TNFalpha. To investigate the functional consequences of SUR1 expression after SAH, we studied the effect of the potent, selective SUR1 inhibitor, glibenclamide. We examined barrier permeability (immunoglobulin G, IgG extravasation), and its correlate, the localization of the tight junction protein, zona occludens 1 (ZO-1). SAH caused a large increase in barrier permeability and disrupted the normal junctional localization of ZO-1, with glibenclamide significantly reducing both effects. In addition, SAH caused large increases in markers of inflammation, including TNFalpha and NFkappaB, and markers of cell injury or cell death, including IgG endocytosis and caspase-3 activation, with glibenclamide significantly reducing these effects. We conclude that block of SUR1 by glibenclamide may ameliorate several pathologic effects associated with inflammation that lead to cortical dysfunction after SAH.

Clazosentan, an endothelin receptor antagonist, prevents early hypoperfusion during the acute phase of massive experimental subarachnoid hemorrhage: a laser Doppler flowmetry study in rats

Object

Acute cerebral hypoperfusion and early disturbances in cerebral autoregulation after subarachnoid hemorrhage (SAH) have been demonstrated repeatedly and have been shown to contribute significantly to acute and secondary brain injury. Acute vasoconstriction has been identified as a major contributing factor. Although increasing evidence implicates endothelin (ET)–1 in the development of cerebral vasospasm, its role in the acute phase after SAH has not yet been investigated. The purpose of this study was to further determine the role of ET in the first minutes to hours after massive experimental SAH induced by prophylactic treatment with the ET receptor antagonist clazosentan.

Methods

Subarachnoid hemorrhage was induced in 22 anesthetized rats by injection of 0.5-ml arterial, nonheparinized blood into the cisterna magna over the course of 60 seconds. In addition to monitoring intracranial pressure (ICP) and mean arterial blood pressure, laser Doppler flowmetry (LDF) probes were placed stereotactically over the cranial windows to allow online recording of cerebral blood flow (CBF) starting 30 minutes prior to SAH and continuing for 3 hours after SAH. The control group (Group A, 11 rats) received vehicle saline solution via a femoral catheter before SAH, and a second group (Group B, 11 rats) was treated prophylactically with clazosentan, an ETA receptor antagonist. Treatment was started 30 minutes prior to bolus injection (1 mg/kg body weight), immediately followed by a continuous infusion of 1 mg/kg body weight/hr until the end of the experiment.

Results

Induction of SAH in the rats caused an immediate increase in ICP, which led to an acute decrease in cerebral perfusion pressure (CPP). Perfusion, as measured with LDF, was found to have decreased relative to baseline by 30 ±20% in the control group and 20 ±9% in the clazosentan-treated group. Intracranial pressure and CPP recovered comparably in both groups thereafter within minutes. Control animals demonstrated prolonged hypoperfusion with a loss of autoregulation independent of CPP changes, finally approaching 80% of baseline values toward the end of the experiment. The authors observed that clazosentan did not influence peracute CPP-dependent hypoperfusion, but prevented continuous CBF reduction. Laser Doppler flowmetry perfusion readings remained depressed in control animals at 73 ±19% of baseline in comparison with 106 ±25% of baseline in clazosentan-treated animals (p = 0.001).

Conclusions

The first hours after a massive experimental SAH can be characterized by a CPP-independent compromise in cerebral perfusion. Prophylactic treatment with the ET receptor antagonist clazosentan prevented hypoperfusion. It is known that in the first days after SAH, a reduction in CBF correlates clinically to high-grade SAH. Although research currently focuses on delayed vasospasm, administration of vasoactive drugs in the acute phase of SAH may reverse perfusion deficits and improve patient recovery.

Monocyte chemoattractant protein–1 predicts outcome and vasospasm following aneurysmal subarachnoid hemorrhage

Object

Despite efforts to elucidate both the molecular mechanism and the clinical predictors of vasospasm after aneurysmal subarachnoid hemorrhage (ASAH), its pathogenesis remains unclear. Monocyte chemoattractant protein–1 (MCP-1) is a chemokine that has been firmly implicated in the pathophysiology of vasospasm and in neural tissue injury following focal ischemia in both animal models and human studies. The authors hypothesized that MCP-1 would be found in increased concentrations in the blood and cerebrospinal fluid (CSF) of patients with ASAH and would correlate with both outcome and the occurrence of vasospasm.

Methods

Seventy-seven patients who presented with ASAH were prospectively enrolled in this study between July 2001 and May 2002. Using an enzyme-linked immunosorbent assay, MCP-1 levels were measured in serum daily and in CSF when available. The mean serum and CSF MCP-1 concentrations were calculated for each patient throughout the entire hospital stay. Neurological outcome was evaluated at discharge or 14 days posthemorrhage using the modified Rankin Scale. Vasospasm was evaluated on angiography.

Results

The serum MCP-1 concentrations correlated with negative outcome such that a 10% increase in concentration predicted a 25% increase in the probability of a poor outcome, whereas the serum MCP-1 levels did not correlate with vasospasm. Concentrations of MCP-1 in the CSF, however, proved to be significantly higher in patients with angiographically demonstrated vasospasm.

Conclusions

These findings suggest a role for MCP-1 in neurological injury and imply that it may act as a biomarker of poor outcome in the serum and of vasospasm in the CSF.

Progesterone prevents traumatic brain injury-induced intestinal nuclear factor kappa B activation and proinflammatory cytokines expression in male rats

We have previously shown that traumatic brain injury (TBI) can induce an upregulation of nuclear factor kappa B (NF-κB) and proinflammatory cytokines in the gut, which play an important role in the pathogenesis of acute gut mucosal injury mediated by inflammation. In this work, we investigated whether progesterone administration modulated intestinal NF-κB activity and proinflammatory cytokines expression after TBI in male rats. As a result, we found that administration of progesterone following TBI could decrease NF-κB binding activity, NF-κB p65 protein expression, and concentrations of interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in the gut. TBI-induced damages of gut structure were ameliorated after progesterone injections. The results of the present study suggest that the therapeutic benefit of post-TBI progesterone injections might be due to its inhibitory effects on intestinal NF-κB activation and proinflammatory cytokines expression.

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.

CONTROVERSIES IN THE ENDOVASCULAR MANAGEMENT OF CEREBRAL VASOSPASM AFTER INTRACRANIAL ANEURYSM RUPTURE AND FUTURE DIRECTIONS FOR THERAPEUTIC APPROACHES

CEREBRAL VASOSPASM IS one of the leading causes of morbidity and mortality after aneurysmal subarachnoid hemorrhage. Despite maximal medical therapy, however, up to 15% of patients surviving the ictus of subarachnoid hemorrhage experience stroke or death from vasospasm. For those cases of vasospasm that are refractory to medical treatment, endovascular techniques are frequently used, including balloon angioplasty with or without intra-arterial infusion of vasodilators, combined endovascular modalities, and aortic balloon devices. In this article, we review each of these therapies and their expanding role in the management of this condition. Moving forward, rigorous prospective outcome assessments after endovascular treatment of cerebral vasospasm are necessary to clearly delineate the efficacy and indications for these techniques.

The "devil's touch"; visual loss and orbital surgery. A synopsis of the Mustardé Lecture, 2006

Visual loss is a devastating complication after orbital surgery, particularly that at the orbital apex or alongside the optic nerve. The clinical characteristics of 14 such patients, representing less than 1% of orbital surgery performed, are presented and the possible mechanisms discussed. The majority of patients suffered a posterior ischaemic optic neuropathy and this is likely to be related to postoperative vasospasm induced by extravasated blood and inflammatory mediators.

THE IMPACT OF MICROSURGICAL FENESTRATION OF THE LAMINA TERMINALIS ON SHUNT-DEPENDENT HYDROCEPHALUS AND VASOSPASM AFTER ANEURYSMAL SUBARACHNOID HEMORRHAGE

OBJECTIVE

Chronic hydrocephalus requiring shunt placement and cerebral vasospasm are common complications after aneurysmal subarachnoid hemorrhage. Recent publications have investigated the possibility that microsurgical fenestration of the lamina terminalis during aneurysm surgery may reduce the incidence of shunt-dependent hydrocephalus and cerebral vasospasm. We reviewed a single-surgeon series to compare postsurgical outcomes of patients who underwent fenestration of the lamina terminalis against those who did not.

METHODS

This study is a retrospective review of the medical records of 369 consecutive patients with aneurysmal subarachnoid hemorrhage admitted to Columbia University Medical Center between January 2000 and July 2006. All patients underwent craniotomy and clipping of at least one ruptured cerebral aneurysm by a single neurosurgeon (ESC). The incidences of shunt-dependent hydrocephalus, conversion from acute hydrocephalus on admission to chronic hydrocephalus, and clinical cerebral vasospasm were compared in patients who underwent fenestration of the lamina terminalis with those who did not. The patient cohort was thus divided into three subgroups: 1) patients whose operative records clearly indicated that they underwent fenestration of the lamina terminalis, 2) patients whose operative records clearly indicated that they did not undergo fenestration of the lamina terminalis, and 3) patients whose operative records did not indicate one way or another whether they received fenestration of the lamina terminalis. We performed two separate analyses by comparing the postsurgical outcomes in those patients who were fenestrated versus those who were definitively not fenestrated and comparing the postsurgical outcomes in those patients who were fenestrated versus those who were not plus those whose records did not document fenestration. To further control for any cohort differences, we performed a comparison between patients who were fenestrated and those who were not after matching 1:1 for presenting radiographic and clinical characteristics predictive of hydrocephalus and vasospasm. Outcomes were compared using logistic regression and multivariable analysis.

RESULTS

In the first model, fenestrated patients had a shunt rate, conversion rate, and rate of clinical vasospasm of 25, 50, and 23%, respectively, versus 20, 27, and 27% in nonfenestrated patients, respectively (P = 0.28, 0.21, and 0.32, respectively). In the second model, the nonfenestrated patients plus nondocumented patients had a shunt rate, conversion rate, and rate of clinical vasospasm of 16, 40, and 20%, respectively (P = 0.19, 0.33, and 0.60, respectively). In the matched cohort, fenestrated patients had a shunt rate, conversion rate, and rate of clinical vasospasm of 29, 67, and 20%, respectively, versus 20, 25, and 25% in nonfenestrated patients, respectively (P = 0.30, 0.24, and 0.20, respectively).

CONCLUSION

In contrast to other retrospective multisurgeon series, our retrospective single-surgeon series suggests that microsurgical fenestration of the lamina terminalis may not reduce the incidence of shunt-dependent hydrocephalus or cerebral vasospasm after aneurysmal subarachnoid hemorrhage. A prospective multicenter trial is needed to definitively address the use of this maneuver.

Effect of raloxifene on cerebral vasospasm following experimental subarachnoid hemorrhage in rats

The effect of raloxifene on cerebral vasospasm following experimental subarachnoid hemorrhage (SAH) was investigated in a rat model. Seven groups of seven rats underwent no SAH, no treatment; SAH only; SAH plus vehicle; SAH plus 3 days intraperitoneal raloxifene treatment; SAH plus 4 days intraperitoneal raloxifene treatment; SAH plus 3 days intrathecal raloxifene treatment; and SAH plus 4 days intrathecal raloxifene treatment. The basilar artery cross-sectional areas were measured at 72 or 96 hours following SAH. The results showed raloxifene decreased SAH-induced cerebral vasospasm in all treatment groups, and suggested no difference between intraperitoneal and intrathecal application, or between 3 days and 4 days of raloxifene treatment. The present study demonstrates that raloxifene is a potential therapeutic agent against cerebral vasospasm after SAH.

Leflunomide prevents vasospasm secondary to subarachnoid haemorrhage

BACKGROUND

Though cerebral vasospasm is one of the most serious complications of subarachnoid haemorrhage (SAH), its complex pathogenesis is poorly understood and available clinical treatment options are unsatisfactory. This study was designed to examine the efficacy of leflunomide, an immunomodulatory agent with inhibitory properties, on vascular smooth muscle cell proliferation and inflammation in a rabbit cerebral vasospasm model.

METHODS

Twenty-two adult New-Zealand rabbits were assigned to 4 groups: control, SAH, SAH plus vehicle, SAH plus leflunomide. Subarachnoid haemorrhage was induced by administration of 1 ml of fresh unheparinised autologous arterial blood into the cisterna magna. Oral leflunomide (2 mg/kg) or vehicle treatment was started 12 h after the induction of subarachnoid haemorrhage and administered once a day. Three days later, the animals were sacrificed and the basilar artery was examined histologically for the lumen area and the thickness of the vessel wall. Inflammatory reaction was also examined by counting white blood cells within the vessel wall by means of light microscopic examination using haematoxylin and eosin staining.

FINDINGS

Severe and moderate vasospasms were detected in the basilar artery of the SAH and SAH plus vehicle treated groups, respectively. Leflunomide effectively reduced the vasospasm of the basilar artery. Compared to the vehicle treated group, leflunomide significantly reduced the lumen area (p < 0.01) and hyperplasia of the vessel wall (p < 0.01). Although inflammatory response within the vessel wall was reduced in the leflunomide treated group, no statistical significance was found between groups (p = 0.07).

CONCLUSION

This study demonstrates for the first time that leflunomide treatment attenuates cerebral vasospasm in a rabbit SAH model while inflammatory reaction in the vessel wall is not affected. Although further studies are needed to reveal its molecular mechanisms in relieving vasospasm, leflunomide may provide a therapeutic potential for human cerebral vasospasm induced by SAH.

Advances in vasospasm treatment and prevention

Outcome after aSAH depends on several factors, including the severity of the initial event, perioperative medical management, surgical variables, and the incidence of complications. Cerebral vasospasm (CV) is ure to consistently respond to treatment, emphasizing the need for further research into the underlying mechanisms of SAH-induced cerebrovascular dysfunction. To this end, our paper reviews the relevant literature on the main therapies employed for CV after aSAH and discusses possible avenues for future investigations. Current management of this condition consists of maximal medical therapy, including triple H regimen and oral administration of calcium antagonists, followed by endovascular balloon angioplasty and/or injection of vasodilatory agents for refractory cases. As the precise pathophysiology of CV is further elucidated, the development of promising investigational therapies will follow.

Early plasma complement C3a levels correlate with functional outcome after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Studies have documented an inflammatory response in the circulating plasma and cerebrospinal fluid of patients with aneurysmal subarachnoid hemorrhage (aSAH). In particular, early upregulation of several complement proteins, including C3a, C4a, and C5b-9, has been demonstrated after the initial hemorrhagic insult. The inflammatory actions of the complement cascade are largely mediated through the anaphylatoxins, C3a and C5a. Recent investigations have established a critical role for C3a in the pathogenesis of cerebral ischemia. We attempt to confirm that plasma C3a and C5a values are elevated in patients with aSAH and to determine whether or not these levels are reliable independent predictors of functional outcome irrespective of clinical presentation.

METHODS

Fifty-two patients with aSAH were prospectively enrolled and stratified according to admission Hunt and Hess grade, demographic variables, and functional status at the time of discharge (modified Rankin Scale score). Plasma C3a and C5a levels were determined at early and late time points after aSAH through enzyme-linked immunosorbent assay.

RESULTS

After aSAH, early C3a and C5a values were increased compared with levels in non-SAH control patients (P < 0.001). Univariate analysis demonstrated that elevations in early C3a (P = 0.010) and C5a (P = 0.041) levels and poor admission Hunt and Hess grade (P = 0.015) correlated significantly with unfavorable outcome. In our multivariate model, only early C3a levels retained a strong correlation with outcome when modeled with Hunt and Hess grade (P = 0.009).

CONCLUSION

These results demonstrate an association between early complement C3a levels and outcome after aSAH that seems to be independent of the initial hemorrhage. The findings suggest that inflammatory processes involving C3a may contribute to delayed morbidity and mortality after aneurysmal rupture.

Effects of progesterone on intestinal inflammatory response, mucosa structure alterations, and apoptosis following traumatic brain injury in male rats

BACKGROUND

Traumatic brain injury (TBI) can induce a persistent inflammatory response, histopathological changes, and apoptosis in the gut. Progesterone given after TBI has been shown to reduce the cerebral inflammation and neuronal apoptosis in the brain. However, the effects of progesterone on the inflammatory response, structure alterations, and apoptosis in the intestinal mucosa following TBI has not been investigated.

MATERIALS AND METHODS

Right parietal cortical contusion in male rats was made by using the weight-dropping method. Rats were given 0 or 16 mg/kg injections of progesterone at postinjury at 1 and 6 hours and on days 1, 2, 3, 4, and 5. Gut samples were extracted at 5 days after trauma. We measured the concentrations of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha, and interleukin-6 (IL-6) by enzyme-linked immunosorbent assay; intercellular adhesion molecule-1 expression by immunohistochemistry; intestinal mucosal morphological changes by histopathological study and electron microscopy; and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining.

RESULTS

Administration of progesterone following TBI could decrease the intestinal concentrations of IL-1beta and tumor necrosis factor-alpha, but not IL-6. The level of intercellular adhesion molecule-1 expression in the gut was down-regulated by progesterone. TBI-induced damages of gut structure and apoptosis were attenuated after progesterone injections.

CONCLUSIONS

The results of the present study suggest that post-TBI progesterone administration could suppress the intestinal inflammation, protect the intestinal mucosal structure, and reduce the mucosa apoptosis.

Potential contribution of nuclear factor-kappaB to cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

Nuclear factor-kappaB (NF-kappaB) plays a key role in inflammation, which is involved in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). In the present study, we assessed the potential role of NF-kappaB in regulation of cerebral vasospasm. Nuclear factor-kappaB DNA-binding activity was measured in cultured vascular smooth muscle cells (VSMCs) treated with hemolysate and pyrrolidine dithiocarbamate (PDTC, 80 micromol/L), an inhibitor of NF-kappaB. Forty-two rabbits were divided into three groups: control, SAH, and PDTC groups (n=14 for each group). The caliber of the basilar artery was evaluated. Nuclear factor-kappaB DNA-binding activity and the gene expression levels of cytokines and adhesion molecules in the basilar artery were measured. Immunohistochemical study was performed to assess the expression and localization of tumor necrosis factor (TNF)-alpha, intercellular adhesion molecule (ICAM)-1, and myeloperoxidase (MPO). It was observed that NF-kappaB DNA-binding activity was significantly increased by treatment with hemolysate in cultured VSCMs, but this increase was suppressed by pretreatment with PDTC. Severe vasospasm was observed in the SAH group, which was attenuated in the PDTC group. Subarachnoid hemorrhage could induce increases of NF-kappaB DNA-binding activity and the gene expression levels of TNF-alpha, interleukin (IL)-1 beta, ICAM-1, and vascular cell adhesion molecule (VCAM)-1, which were reduced in the PDTC group. Immunohistochemical study demonstrated that the expression levels of TNF-alpha, ICAM-1, and MPO were all increased in the SAH group, but these increases were attenuated in the PDTC group. Our results suggest that NF-kappaB is activated in the arterial wall after SAH, which potentially leads to vasospasm development through induction of inflammatory response.

Analysis of Intrathecal Interleukin-6 As a Potential Predictive Factor for Vasospasm in Subarachnoid Hemorrhage

OBJECTIVE

Inflammatory response seems to be one of the relevant pathophysiological aspects for developing vasospasm in subarachnoid hemorrhage. The probable diagnostic value of intrathecal proinflammatory markers is still unclear and is assessed in this study.

METHODS

We analyzed daily clinical data and laboratory tests of the cerebrospinal fluid (CSF) of 64 patients with mostly poor-grade subarachnoid hemorrhage during a period of 14 days. Special attention was given to the relationship between the development of vasospasm and the time course of the intrathecal interleukin (IL)-6 concentrations in CSF (IL-6CSF). The potential power of IL-6CSF for predicting vasospasm was studied.

RESULTS

Vasospasm developed in 28.1% of the patients, with a mean onset of 6.4 days after bleeding, and was detected by conventional methods. Patients with vasospasm demonstrated statistically significant higher median values of IL-6CSF on Days 4 and 5 (P < 0.05). Most importantly, the increase of IL-6CSF preceded the conventional signs of vasospasm. A cut-off value of IL-6CSF of at least 2000 pg/ml on Day 4 yielded an 11.72-fold higher relative risk (95% confidence interval, 2.93-46.60) of developing vasospasm, predicting vasospasm with a sensitivity of 88.9% and a specificity of 78.3%. We found a statistically significant correlation between IL-6CSF and delayed cerebral ischemia for Day 7 (P = 0.03). However, there was no correlation with IL-6CSF on any other day and outcome.

CONCLUSION

IL-6CSF seems to be a reliable early marker for predicting vasospasm after subarachnoid hemorrhage on Days 4 and 5 before clinical onset.

Leukocyte-endothelial cell interactions in chronic vasospasm after subarachnoid hemorrhage

Leukocyte-endothelial cell interactions appear to be the root cause of chronic vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). Early clinical observations and indirect experimental evidence suggested an association between inflammation and chronic vasospasm. Early clinical observations in patients with post-hemorrhagic vasospasm included pyrexia, leukocytosis and the presence of circulating immune complexes. Inflammatory infiltrates and increased levels of immunoglobulins and complement fractions within spastic cerebral arteries also provided early evidence for an inflammatory mechanism underlying chronic vasospasm. Early indirect experimental evidence included the ability to reproduce chronic vasospasm with the introduction of inflammatory agents into the subarachnoid space and the inhibition of vasospasm with anti-inflammatory agents. Currently, however, there is an increasing body of direct molecular evidence that demonstrates the pivotal role of leukocyte-endothelial cell interactions in the development of chronic vasospasm. Cell adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1) and endothelial (E)-selectin mediate interactions between circulating leukocytes and cerebral endothelium. Following aSAH, ICAM-1 is up-regulated in cerebral endothelial cells and along with other cell adhesion molecules, can be detected in the serum and cerebrospinal fluid (CSF) of patients with post-hemorrhagic vasospasm. Monoclonal antibody blocking experiments have demonstrated that the prevention of leukocyte extravasation into the subarachnoid space prevents chronic vasospasm. Similarly, drugs like ibuprofen, which prevent ICAM-1 up-regulation and transendothelial cell migration of leukocytes, prevent vasospasm. In this review, we highlight early observations that suggested an association between inflammation and post-hemorrhagic vasospasm, detail the role of leukocyte-endothelial cell interactions in the development of chronic vasospasm and discuss therapeutic implications of an inflammatory etiology of post-hemorrhagic cerebral vasospasm.

Impact of Intrascalar Blood on Hearing

OBJECTIVE/HYPOTHESIS

The objective of this controlled animal study was to evaluate the effects of intrascalar blood on hearing.

MATERIAL AND METHODS

Eight guinea pigs underwent intrascalar administration of their own blood in one ear and control solution in the contralateral ear. Solutions were applied through cochleostomy to the scala tympani. Compound action potential (CAP) thresholds were determined before administration and at different intervals for 2 months thereafter.

RESULTS

Immediate deterioration of thresholds was seen mainly in the high-frequency range, averaging 27 dB and 20 dB in the study and control groups, respectively. At day 3, threshold shifts recovered in the control group but remained in the low-frequency range in the study group. An extensive recovery was seen in both groups. However, permanent threshold shifts persisted. There was an enhanced shift of thresholds of up to 7 dB in the study group.

CONCLUSIONS

Even small amounts of intrascalar blood seem to cause transient and permanent detrimental effects on cochlear function. In procedures involving opening of the otic capsule-like stapes surgery and cochlear implantation with hearing preservation-minimizing surgical blood admixture to intracochlear compartments seems therefore fundamental.

Controlled release of lipopolysaccharide in the subarachnoid space of rabbits induces chronic vasospasm in the absence of blood

OBJECTIVE

Leukocyte-endothelial cell interactions appear to play a role in the development of vasospasm after SAH. Using a purely inflammatory protein, LPS, we evaluated the effect of inflammation on the development of chronic vasospasm in the absence of blood and compared it to SAH-induced vasospasm in rabbits.

METHODS

Lipopolysaccharide was incorporated into EVAc polymers to produce 20% LPS/EVAc polymers (wt/wt). Rabbits (n = 23) were randomized to 4 experimental groups: (1) empty polymer (n = 6), (2) SAH (n = 5), (3) 0.7 mg/kg polymeric LPS dose (n = 6), and (4) 1.4 mg/kg polymeric LPS dose (n = 6). Blood and polymers were inserted into the cisterna magna. The rabbits were killed 3 days postoperatively, and the basilar arteries were harvested for morphometric analysis. Clinical response and lumen patencies were analyzed using ANOVA and a post hoc Newman-Keuls Multiple Comparisons test.

RESULTS

Significant narrowing of the basilar artery was observed by insertion of 20% LPS/EVAc polymers into the subarachnoid space at a polymeric dose of 1.4 mg/kg (actual dose, 66 microg kg(-1) d(-1)) (75.4% +/- 4.2%; P < .01) and by SAH (80.3% +/- 8.1%; P < .01) as compared with the empty polymer group. A trend toward narrowing was observed in the 0.7 mg/kg polymeric LPS dose group (actual dose, 33 microg kg(-1) d(-1)) (85.2% +/- 2.6%; P > .05). Symptoms associated with SAH were noted in 50% of the rabbits in the 0.7 mg/kg LPS group and in 100% of rabbits in the 1.4 mg/kg LPS group.

CONCLUSION

Controlled release of LPS into the subarachnoid space of rabbits produced chronic vasospasm in a dose-dependent manner. At a polymeric dose of 1.4 mg/kg, LPS-induced vasospasm was equivalent to that induced by SAH. This suggests that LPS and SAH may induce vasospasm through similar mechanisms and provides further evidence that inflammation plays a central role in the etiology of chronic vasospasm.

Gene expression and molecular changes in cerebral arteries following subarachnoid hemorrhage in the rat

Object

The authors investigated early changes in the cerebral arteries of rats that occur after subarachnoid hemorrhage (SAH).

Methods

Messenger RNA was investigated by performing microarray and quantitative real-time polymerase chain reaction (PCR) analyses, and protein expression was shown by performing immunohistochemical studies. The array data indicated that the initial processes that occur after SAH involve activation of genes involved in angiogenesis, inflammation, and extracellular matrix (ECM) remodeling. The real-time PCR investigation confirmed upregulation of genes that were observed using the microarray to be regulated, including iNOS, MMP13, and cxcl2. The authors also verified the upregulation of previously implicated genes for G-protein–coupled receptors (endothelin B [ETB], angiotensin 1 [AT1], and AT2) and metalloproteinase 9. The results of an immunohistochemical study confirmed that receptor genes that were seen to be regulated produced an increase in protein expression. Double immunostaining of rat cerebral arteries with endothelial cell– or smooth-muscle cell–specific antibodies verified that an increase in ETB, 5-hydrotryptamine (5-HT1B), and 5-HT1D receptor expression occurs in smooth-muscle cells.

Conclusions

Processes occurring after SAH lead to enhanced arterial contractility and ECM remodeling either directly or through angiogenesis and inflammation. These processes are active via an increase in metalloproteinase expression, the presence of proangiogenic factors, and the expression of proinflammatory genes.

Caspase-dependent cell death involved in brain damage after acute subdural hematoma in rats

Traumatic brain injury is associated with acute subdural hematoma (ASDH) that worsens outcome. Although early removal of blood can reduce mortality, patients still die or remain disabled after surgery and additional treatments are needed. The blood mass and extravasated blood induce pathomechanisms such as high intracranial pressure (ICP), ischemia, apoptosis and inflammation which lead to acute as well as delayed cell death. Only little is known about the basis of delayed cell death in this type of injury. Thus, the purpose of the study was to investigate to which extent caspase-dependent intracellular processes are involved in the lesion development after ASDH in rats. A volume of 300microL blood was infused into the subdural space under monitoring of ICP and tissue oxygen concentration. To asses delayed cell death mechanisms, DNA fragmentation was measured 1, 2, 4 and 7 days after ASDH by TUNEL staining, and the effect of the pan-caspase inhibitor zVADfmk on lesion volume was assessed 7 days post-ASDH. A peak of TUNEL-positive cells was found in the injured cortex at day 2 after blood infusion (53.4+/-11.6 cells/mm(2)). zVADfmk (160ng), applied by intracerebroventricular injection before ASDH, reduced lesion volume significantly by more than 50% (vehicle: 23.79+/-7.62mm(3); zVADfmk: 9.06+/-4.08). The data show for the first time that apoptotic processes are evident following ASDH and that caspase-dependent mechanisms play a crucial role in the lesion development caused by the blood effect on brain tissue.

A review of current and future medical therapies for cerebral vasospasm following aneurysmal subarachnoid hemorrhage

✓In an effort to help clarify the current state of medical therapy for cerebral vasospasm, the authors reviewed the relevant literature on the established medical therapies used for cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH), and they discuss burgeoning areas of investigation. Despite advances in the treatment of aneurysmal SAH, cerebral vasospasm remains a common complication and has been correlated with a 1.5- to threefold increase in death during the first 2 weeks after hemorrhage. A number of medical, pharmacological, and surgical therapies are currently in use or being investigated in an attempt to reverse cerebral vasospasm, but only a few have proven to be useful. Although much has been elucidated regarding its pathophysiology, the treatment of cerebral vasospasm remains a dilemma. Although a poor understanding of SAH-induced cerebral vasospasm pathophysiology has, to date, hampered the development of therapeutic interventions, current research efforts promise the eventual production of new medical therapies.

Molecular mechanisms of early brain injury after subarachnoid hemorrhage

OBJECTIVES

Increasing body of experimental and clinical data indicates that early brain injury after initial bleeding largely contributes to unfavorable outcome after subarachnoid hemorrhage (SAH). This review presents molecular mechanisms underlying brain injury at its early stages after SAH.

METHODS

PubMed was searched using term 'subarachnoid hemorrhage' and key words referring to molecular and cellular pathomechanisms of SAH-induced early brain injury.

RESULTS

The authors reviewed intracranial phenomena and molecular agents that contribute to the early development of pathological sequelae of SAH in cerebral and vascular tissues, including cerebral ischemia and its interactions with injurious blood components, blood-brain barrier disruption, brain edema and apoptosis.

DISCUSSION

It is believed that detailed knowledge of molecular signaling pathways after SAH will serve to improve therapeutic interventions. The most promising approach is the protection of neurovascular unit including anti-apoptosis therapy.

Systemic administration of simvastatin after the onset of experimental subarachnoid hemorrhage attenuates cerebral vasospasm

OBJECTIVE

Experimental evidence suggests that intercellular adhesion molecule-1 mediated leukocyte extravasation contributes to the pathogenesis of cerebral vasospasm. Simvastatin, an HMG-CoA reductase inhibitor, decreases intercellular adhesion molecule-1 expression and competitively inhibits leukocyte intercellular adhesion molecule-1 binding. We hypothesized that administration of simvastatin after the onset of subarachnoid hemorrhage (SAH) would attenuate perivascular granulocyte migration and ameliorate cerebral vasospasm in a rabbit model of SAH.

METHODS

New Zealand white rabbits (n = 15) underwent injection of autologous blood into the cisterna magna or sham surgery followed by subcutaneous injection of simvastatin (40 mg/kg) or vehicle 30 minutes, 24 hours, and 48 hours after SAH or sham surgery. Seventy-two hours later, basilar artery lumen diameter was measured by in situ perfusion/fixation and image analysis. CD-18 monoclonal antibody stained perivascular granulocytes and macrophages were counted under light microscopy.

RESULTS

In vehicle treated rabbits, mean +/- standard deviation basilar artery diameter was reduced 3 days after SAH (n = 5) versus sham (n = 5) rabbits (0.49 +/- 0.08 mm versus 0.75 +/- 0.03 mm, P < 0.01). After SAH, mean +/- standard deviation basilar artery diameter was greater in simvastatin (n = 5) treated rabbits versus vehicle (n = 5) (0.63 +/- 0.04 mm versus 0.49 +/- 0.08 mm, P < 0.01). In vehicle treated rabbits, SAH resulted in an increase in the mean +/- standard deviation perivascular CD18 cell count (sham-vehicle, 2.8 +/- 2; SAH-vehicle 90 +/- 27; P < 0.01). Subcutaneous administration of simvastatin attenuated this increase in perivascular CD18-positive cells after SAH (SAH statin, 41.6 +/- 13; SAH vehicle, 90 +/- 27; P < 0.001).

CONCLUSION

Subcutaneous administration of simvastatin after the onset of SAH attenuates perivascular granulocyte migration and ameliorates basilar artery vasospasm after experimental SAH in rabbits. 5-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, such as simvastatin, may potentially serve as agents in the prevention of cerebral vasospasm after SAH.

Preconditioning with thrombin can be protective or worsen damage after endothelin-1-induced focal ischemia in rats

The serine protease thrombin has shown direct neuroprotective and neurotoxic effects on brain tissue in cerebral ischemia. Previous data suggested that thrombin-induced protection in vivo can be achieved by preconditioning rather than by acute treatment. In the current work, we used a model of mild ischemia to investigate the effects of preischemic intracerebral thrombin injection on neural damage. By intracerebral injection of endothelin-1 in freely moving animals, we achieved middle cerebral artery occlusion (MCAO), and 7 days postischemia we performed histological quantification of the infarct areas. Thrombin was injected as a preconditioning stimulus intracerebrally 7 days or 2 and 3 days before ischemia. For acute treatment, thrombin was injected 20 min before MCAO. Thrombin induced significant neuroprotection when given 7 days before endothelin-1-induced MCAO but was deleterious when given 2 and 3 days before the insult. The deleterious effect was not seen when thrombin was given acutely before ischemia. Our data demonstrate that preconditioning with thrombin can protect against damage or worsen ischemic damage. Its effect depended on the time interval between thrombin injection and insult. A low dose of thrombin did not induce a major deleterious effect in the acute phase of the infarct development after mild transient ischemia.

Role of c-Jun N-Terminal Kinase in Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage

Background and Purpose— Inflammation could play a role in cerebral vasospasm after subarachnoid hemorrhage (SAH). SP600125 a c-Jun N-terminal kinase (JNK) inhibitor reduces inflammation. The present study examined if SP600125 could reduce cerebral vasospasm.

Methods— Twenty-seven dogs were assigned to 5 groups: control, SAH, SAH plus dimethyl sulfoxide (DMSO), SAH plus SP600125 (10 μmol/L), and SAH plus SP600125 (30 μmol/L). SAH was induced by the injection of autologous blood into the cisterna magna on day 0 and day 2. Angiograms were evaluated on day 0 and day 7. The behavior of the dogs was evaluated daily. The activation of the JNK pathway, the infiltration of leukocytes, and the production of cytokines were also evaluated.

Results— Severe vasospasm was observed in the basilar artery of SAH and DMSO dogs. The JNK signaling pathway was activated in the basilar artery after SAH and SP600125 reduced angiographic and morphological vasospasm and improved behavior scores with a concomitant reduction of infiltrated leukocytes and IL-6 production.

Conclusions— These results demonstrate that SP600125 attenuated cerebral vasospasm through a suppressed inflammatory response, which may provide a novel therapeutic target for cerebral vasospasm.