The safety and efficacy of cyclosporine A in the prevention of vasospasm in patients with Fisher grade 3 subarachnoid hemorrhages: a pilot study

Auricular Vagus Nerve Stimulation Mitigates Inflammation and Vasospasm in Subarachnoid Hemorrhage: A Randomized Trial

Background

Inflammation contributes to morbidity following subarachnoid hemorrhage (SAH). Transauricular vagus nerve stimulation (taVNS) offers a noninvasive approach to target the inflammatory response following SAH.

Methods

In this prospective, triple-blinded, randomized, controlled trial, twenty-seven patients were randomized to taVNS or sham stimulation. Blood and cerebrospinal fluid (CSF) were collected to quantify inflammatory markers. Cerebral vasospasm severity and functional outcomes (modified Rankin Scale, mRS) were analyzed.

Results

No adverse events occurred. Radiographic vasospasm was significantly reduced (p = 0.018), with serial vessel caliber measurements demonstrating a more rapid return to normal than sham (p < 0.001). In the taVNS group, TNF-α was significantly reduced in both plasma (days 7 and 10) and CSF (day 13); IL-6 was also significantly reduced in plasma (day 4) and CSF (day 13) (p < 0.05). Patients receiving taVNS had higher rates of favorable outcomes at discharge (38.4% vs 21.4%) and first follow-up (76.9% vs 57.1%), with significant improvement from admission to first follow-up (p = 0.014), unlike the sham group (p = 0.18). The taVNS group had a significantly lower rate of discharge to skilled nursing facility or hospice (p = 0.04).

Conclusion

taVNS is a non-invasive method of neuro- and systemic immunomodulation. This trial supports that taVNS following SAH can mitigate the inflammatory response, reduce radiographic vasospasm, and potentially improve functional and neurological outcomes. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT04557618.

Non-invasive Auricular Vagus nerve stimulation for Subarachnoid Hemorrhage (NAVSaH): Protocol for a prospective, triple-blinded, randomized controlled trial

Background

Inflammation has been implicated in driving the morbidity associated with subarachnoid hemorrhage (SAH). Despite understanding the important role of inflammation in morbidity following SAH, there is no current effective way to modulate this deleterious response. There is a critical need for a novel approach to immunomodulation that can be safely, rapidly, and effectively deployed in SAH patients. Vagus nerve stimulation (VNS) provides a non-pharmacologic approach to immunomodulation, with prior studies demonstrating VNS can reduce systemic inflammatory markers, and VNS has had early success treating inflammatory conditions such as arthritis, sepsis, and inflammatory bowel diseases. The aim of the Non-invasive Auricular Vagus nerve stimulation for Subarachnoid Hemorrhage (NAVSaH) trial is to translate the use of non-invasive transcutaneous auricular VNS (taVNS) to spontaneous SAH, with our central hypothesis being that implementing taVNS in the acute period following spontaneous SAH attenuates the expected inflammatory response to hemorrhage and curtails morbidity associated with inflammatory-mediated clinical endpoints.

Materials and methods

The overall objectives for the NAHSaH trial are to 1) Define the impact that taVNS has on SAH-induced inflammatory markers in the plasma and cerebrospinal fluid (CSF), 2) Determine whether taVNS following SAH reduces radiographic vasospasm, and 3) Determine whether taVNS following SAH reduces chronic hydrocephalus. Following presentation to a single enrollment site, enrolled SAH patients are randomly assigned twice daily treatment with either taVNS or sham stimulation for the duration of their intensive care unit stay. Blood and CSF are drawn before initiation of treatment sessions, and then every three days during a patient's hospital stay. Primary endpoints include change in the inflammatory cytokine TNF-α in plasma and cerebrospinal fluid between day 1 and day 13, rate of radiographic vasospasm, and rate of requirement for long-term CSF diversion via a ventricular shunt. Secondary outcomes include exploratory analyses of a panel of additional cytokines, number and type of hospitalized acquired infections, duration of external ventricular drain in days, interventions required for vasospasm, continuous physiology data before, during, and after treatment sessions, hospital length of stay, intensive care unit length of stay, and modified Rankin Scale score (mRS) at admission, discharge, and each at follow-up appointment for up to two years following SAH.

Discussion

Inflammation plays a central role in morbidity following SAH. This NAVSaH trial is innovative because it diverges from the pharmacologic status quo by harnessing a novel non-invasive neuromodulatory approach and its known anti-inflammatory effects to alter the pathophysiology of SAH. The investigation of a new, effective, and rapidly deployable intervention in SAH offers a new route to improve outcomes following SAH.

Trial registration

Clinical Trials Registered, NCT04557618. Registered on September 21, 2020, and the first patient was enrolled on January 4, 2021.

Inflammatory Markers as Predictors of Shunt Dependency and Functional Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage

The mechanisms underlying post-hemorrhagic hydrocephalus (PHH) development following subarachnoid hemorrhage (SAH) are not fully understood, which complicates informed clinical decisions regarding the duration of external ventricular drain (EVD) treatment and prevents the prediction of shunt-dependency in the individual patient. The aim of this study was to identify potential inflammatory cerebrospinal fluid (CSF) biomarkers of PHH and, thus, shunt-dependency and functional outcome in patients with SAH. This study was a prospective observational study designed to evaluate inflammatory markers in ventricular CSF. In total, 31 Patients with SAH who required an EVD between June 2019 and September 2021 at the Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark, were included. CSF samples were collected twice from each patient and analyzed for 92 inflammatory markers via proximity extension assay (PEA), and the prognostic ability of the markers was investigated. In total, 12 patients developed PHH, while 19 were weaned from their EVD. Their 6-month functional outcome was determined with the modified Rankin Scale. Of the 92 analyzed inflammatory biomarkers, 79 were identified in the samples. Seven markers (SCF, OPG, LAP TGFβ1, Flt3L, FGF19, CST5, and CSF1) were found to be predictors of shunt dependency, and four markers (TNFα, CXCL5, CCL20, and IL8) were found to be predictors of functional outcome. In this study, we identified promising inflammatory biomarkers that are able to predict (i) the functional outcome in patients with SAH and (ii) the development of PHH and, thus, the shunt dependency of the individual patients. These inflammatory markers may have the potential to be employed as predictive biomarkers of shunt dependency and functional outcome following SAH and could, as such, be applied in the clinic.

Cyclophilin D-induced mitochondrial impairment confers axonal injury after intracerebral hemorrhage in mice

The mitochondrial permeability transition pore is a nonspecific transmembrane channel. Inhibition of mitochondrial permeability transition pore opening has been shown to alleviate mitochondrial swelling, calcium overload, and axonal degeneration. Cyclophilin D is an important component of the mitochondrial permeability transition pore. Whether cyclophilin D participates in mitochondrial impairment and axonal injury after intracerebral hemorrhage is not clear. In this study, we established mouse models of intracerebral hemorrhage in vivo by injection of autologous blood and oxyhemoglobin into the striatum in Thy1-YFP mice, in which pyramidal neurons and axons express yellow fluorescent protein. We also simulated intracerebral hemorrhage in vitro in PC12 cells using oxyhemoglobin. We found that axonal degeneration in the early stage of intracerebral hemorrhage depended on mitochondrial swelling induced by cyclophilin D activation and mitochondrial permeability transition pore opening. We further investigated the mechanism underlying the role of cyclophilin D in mouse models and PC12 cell models of intracerebral hemorrhage. We found that both cyclosporin A inhibition and short hairpin RNA interference of cyclophilin D reduced mitochondrial permeability transition pore opening and mitochondrial injury. In addition, inhibition of cyclophilin D and mitochondrial permeability transition pore opening protected corticospinal tract integrity and alleviated motor dysfunction caused by intracerebral hemorrhage. Our findings suggest that cyclophilin D is used as a key mediator of axonal degeneration after intracerebral hemorrhage; inhibition of cyclophilin D expression can protect mitochondrial structure and function and further alleviate corticospinal tract injury and motor dysfunction after intracerebral hemorrhage. Our findings provide a therapeutic target for preventing axonal degeneration of white matter injury and subsequent functional impairment in central nervous diseases.

Pathophysiology of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: A Review

Delayed cerebral ischemia is a major predictor of poor outcomes in patients who suffer subarachnoid hemorrhage. Treatment options are limited and often ineffective despite many years of investigation and clinical trials. Modern advances in basic science have produced a much more complex, multifactorial framework in which delayed cerebral ischemia is better understood and novel treatments can be developed. Leveraging this knowledge to improve outcomes, however, depends on a holistic understanding of the disease process. We conducted a review of the literature to analyze the current state of investigation into delayed cerebral ischemia with emphasis on the major themes that have emerged over the past decades. Specifically, we discuss microcirculatory dysfunction, glymphatic impairment, inflammation, and neuroelectric disruption as pathological factors in addition to the canonical focus on cerebral vasospasm. This review intends to give clinicians and researchers a summary of the foundations of delayed cerebral ischemia pathophysiology while also underscoring the interactions and interdependencies between pathological factors. Through this overview, we also highlight the advances in translational studies and potential future therapeutic opportunities.

Interleukin 6 and Aneurysmal Subarachnoid Hemorrhage. A Narrative Review

Interleukin 6 (IL-6) is a prominent proinflammatory cytokine. Neuroinflammation in general, and IL-6 signaling in particular, appear to play a major role in the pathobiology and pathophysiology of aneurysm formation and aneurysmal subarachnoid hemorrhage (SAH). Most importantly, elevated IL-6 CSF (rather than serum) levels appear to correlate with delayed cerebral ischemia (DCI, “vasospasm”) and secondary (“vasospastic”) infarctions. IL-6 CSF levels may also reflect other forms of injury to the brain following SAH, i.e., early brain damage and septic complications of SAH and aneurysm treatment. This would explain why many researchers have found an association between IL-6 levels and patient outcomes. These findings clearly suggest CSF IL-6 as a candidate biomarker in SAH patients. However, at this point, discrepant findings in variable study settings, as well as timing and other issues, e.g., defining proper clinical endpoints (i.e., secondary clinical deterioration vs. angiographic vasospasm vs. secondary vasospastic infarct) do not allow for its routine use. It is also tempting to speculate about potential therapeutic measures targeting elevated IL-6 CSF levels and neuroinflammation in SAH patients. Corticosteroids and anti-platelet drugs are indeed used in many SAH cases (not necessarily with the intention to interfere with detrimental inflammatory signaling), however, no convincing benefit has been demonstrated yet. The lack of a robust clinical perspective against the background of a relatively large body of data linking IL-6 and neuroinflammation with the pathophysiology of SAH is somewhat disappointing. One underlying reason might be that most relevant studies only report correlative data. The specific molecular pathways behind elevated IL-6 levels in SAH patients and their various interactions still remain to be delineated. We are optimistic that future research in this field will result in a better understanding of the role of neuroinflammation in the pathophysiology of SAH, which in turn, will translate into the identification of suitable biomarkers and even potential therapeutic targets.

The role of immune inflammation in aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating disease, which mainly caused by the rupture of an intracranial aneurysm. Clinical trials have demonstrated that cerebral vasospasm (CVS) is not the sole contributor to delayed cerebral ischemia (DCI) and poor outcomes in patients with aSAH. Currently, accumulating evidence suggests that early brain injury (EBI), which occurs within 72 h after the onset of aSAH, lays the foundation for subsequent pathophysiological changes and poor outcomes of patients. The pathological mechanisms of EBI mainly include increased intracranial pressure, oxidative stress, neuroinflammation, blood-brain barrier (BBB) disruption, cerebral edema and cell death. Among them, the brain immune inflammatory responses involve a variety of immune cells and active substances, which play an important role in EBI after aSAH and may be related to DCI and long-term outcomes. Thus, attention should be paid to strategies targeting cerebral immune inflammatory responses. In this review, we discuss the role of immune inflammatory responses in the occurrence and development of aSAH, as well as some inflammatory biomarkers related to CVS, DCI, and aSAH outcomes. In addition, we also summarize the potential therapeutic drugs that target cerebral immune inflammatory responses for patients with aSAH in current research.

Neuroinflammation and Microvascular Dysfunction After Experimental Subarachnoid Hemorrhage: Emerging Components of Early Brain Injury Related to Outcome

Aneurysmal subarachnoid hemorrhage has a high mortality rate and, for those who survive this devastating injury, can lead to lifelong impairment. Clinical trials have demonstrated that cerebral vasospasm of larger extraparenchymal vessels is not the sole contributor to neurological outcome. Recently, the focus of intense investigation has turned to mechanisms of early brain injury that may play a larger role in outcome, including neuroinflammation and microvascular dysfunction. Extravasated blood after aneurysm rupture results in a robust inflammatory response characterized by activation of microglia, upregulation of cellular adhesion molecules, recruitment of peripheral immune cells, as well as impaired neurovascular coupling, disruption of the blood-brain barrier, and imbalances in endogenous vasodilators and vasoconstrictors. Each of these phenomena is either directly or indirectly associated with neuronal death and brain injury. Here, we review recent studies investigating these various mechanisms in experimental models of subarachnoid hemorrhage with special emphasis on neuroinflammation and its effect on microvascular dysfunction. We discuss the various therapeutic targets that have risen from these mechanistic studies and suggest the utility of a multi-targeted approach to preventing delayed injury and improving outcome after subarachnoid hemorrhage.

The role of TLR4 and HO-1 in neuroinflammation after subarachnoid hemorrhage

This review on the mechanisms of neuroinflammation following subarachnoid hemorrhage will focus mainly on toll-like receptor 4 (TLR4), Heme Oxygenase-1 (HO-1), and the role of microglia and macrophages in this process. Vasospasm has long been the focus of research in SAH; however, clinical trials have shown that amelioration of vasospasm does not lead to an improved clinical outcome. This necessitates the need for novel avenues of research. Our work has demonstrated that microglial TLR4 and microglial HO-1, not only affects cognitive dysfunction, but also circadian dysrhythmia in a mouse model of SAH. To attempt to translate these findings, we have also begun investigating macrophages in the cerebrospinal fluid of SAH patients. The goal of this review is to provide an update on the role of TLR4, HO-1, and other signal transduction pathways in SAH-induced neuroinflammation.

Neuroinflammation as a Target for Intervention in Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a sub-type of hemorrhagic stroke associated with the highest rates of mortality and long-term neurological disabilities. Despite the improvement in the management of SAH patients and the reduction in case fatality in the last decades, disability and mortality remain high in this population. Brain injury can occur immediately and in the first days after SAH. This early brain injury can be due to physical effects on the brain such as increased intracranial pressure, herniations, intracerebral, intraventricular hemorrhage, and hydrocephalus. After the first 3 days, angiographic cerebral vasospasm (ACV) is a common neurological complication that in severe cases can lead to delayed cerebral ischemia and cerebral infarction. Consequently, the prevention and treatment of ACV continue to be a major goal. However, most treatments for ACV are vasodilators since ACV is due to arterial vasoconstriction. Other targets also have included those directed at the underlying biochemical mechanisms of brain injury such as inflammation and either independently or as a consequence, cerebral microthrombosis, cortical spreading ischemia, blood–brain barrier breakdown, and cerebral ischemia. Unfortunately, no pharmacologic treatment directed at these processes has yet shown efficacy in SAH. Enteral nimodipine and the endovascular treatment of the culprit aneurysm, remain the only treatment options supported by evidence from randomized clinical trials to improve patients’ outcome. Currently, there is no intervention directly developed and approved to target neuroinflammation after SAH. The goal of this review is to provide an overview on anti-inflammatory drugs tested after aneurysmal SAH.

A Propensity Score-Matched Study of the Use of Non-steroidal Anti-inflammatory Agents Following Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Inflammation may contribute to poor outcomes after aneurysmal subarachnoid hemorrhage (aSAH). Here, we compared outcomes among propensity score-matched cohorts who did and did not receive non-steroidal anti-inflammatory drug (NSAID) use after aSAH.

METHODS

Propensity score-matched analysis of 413 subjects enrolled in the Clazosentan to Overcome Neurological iSChemia and Infarction OccUring after Subarachnoid hemorrhage (CONSCIOUS-1) study. Propensity score matching was performed on the basis of age, sex, baseline National Institutes of Health Stroke Scale score, World Federation of Neurological Societies grade on admission, procedure used for securing aneurysm, and SAH clot burden.

RESULTS

178 patients were matched (89 received NSAIDs, 89 did not). Propensity score matching was considered acceptable. Patients who had received NSAIDs during their hospital stay had significantly lower mortality rate, and reduced duration of intensive care unit stay and total length of hospital stay (P = 0.035, P = 0.009, and P = 0.053, respectively). At 6 weeks, 80.9 % of patients treated with NSAIDs had good functional outcome compared to 68.5 % of matched controls (P = 0.083). There was no significant difference in the proportions of patients who developed delayed ischemic neurological deficits, angiographic vasospasm, or required rescue therapy.

CONCLUSIONS

Inflammation may play a crucial role in the poor outcomes after SAH, and that NSAIDs may be a useful therapeutic option, once validated by larger prospective studies.

An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage

Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.

Inducible nitric oxide synthase (NOS-2) in subarachnoid hemorrhage: Regulatory mechanisms and therapeutic implications

Aneurysmal subarachnoid hemorrhage (SAH) typically carries a poor prognosis. Growing evidence indicates that overabundant production of nitric oxide (NO) may be responsible for a large part of the secondary injury that follows SAH. Although SAH modulates the activity of all three isoforms of nitric oxide synthase (NOS), the inducible isoform, NOS-2, accounts for a majority of NO-mediated secondary injuries after SAH. Here, we review the indispensable physiological roles of NO that must be preserved, even while attempting to downmodulate the pathophysiologic effects of NO that are induced by SAH. We examine the effects of SAH on the function of the various NOS isoforms, with a particular focus on the pathological effects of NOS-2 and on the mechanisms responsible for its transcriptional upregulation. Finally, we review interventions to block NOS-2 upregulation or to counteract its effects, with an emphasis on the potential therapeutic strategies to improve outcomes in patients afflicted with SAH. There is still much to be learned regarding the apparently maladaptive response of NOS-2 and its harmful product NO in SAH. However, the available evidence points to crucial effects that, on balance, are adverse, making the NOS-2/NO/peroxynitrite axis an attractive therapeutic target in SAH.

Inflammation, vasospasm, and brain injury after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) can lead to devastating neurological outcomes, and there are few pharmacologic treatments available for treating this condition. Both animal and human studies provide evidence of inflammation being a driving force behind the pathology of SAH, leading to both direct brain injury and vasospasm, which in turn leads to ischemic brain injury. Several inflammatory mediators that are elevated after SAH have been studied in detail. While there is promising data indicating that blocking these factors might benefit patients after SAH, there has been little success in clinical trials. One of the key factors that complicates clinical trials of SAH is the variability of the initial injury and subsequent inflammatory response. It is likely that both genetic and environmental factors contribute to the variability of patients' post-SAH inflammatory response and that this confounds trials of anti-inflammatory therapies. Additionally, systemic inflammation from other conditions that affect patients with SAH could contribute to brain injury and vasospasm after SAH. Continuing work on biomarkers of inflammation after SAH may lead to development of patient-specific anti-inflammatory therapies to improve outcome after SAH.

Current management of delayed cerebral ischemia: update from results of recent clinical trials

Subarachnoid hemorrhage (SAH) accounts for 5-7% of all strokes worldwide and is associated with high mortality and morbidity. Even after surgical intervention, approximately 30% of patients develop long-term cognitive and neurological deficits that significantly affect their capacity to return to work or daily life unassisted. Much of this stems from a secondary ischemic phenomenon referred to as delayed cerebral ischemia (DCI). While DCI has been historically attributed to the narrowing of the large basal cerebral arteries, it is now recognized that numerous pathways contribute to its pathogenesis, including microcirculatory dysfunction, microthrombosis, cortical spreading depression, and early brain injury. This paper seeks to summarize some of the key pathophysiological events that are associated with poor outcome after SAH, provide a general overview of current methods of treating SAH patients, and review the results of recent clinical trials directed at improving outcome after SAH. The scientific basis of these studies will be discussed, in addition to the available results and recommendations for effective patient management. Therapeutic methods under current clinical investigation will also be addressed. In particular, the mechanisms by which they are expected to elicit improved outcome will be investigated, as well as the specific study designs and anticipated time lines for completion.

Delayed neurological deterioration after subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) causes early brain injury (EBI) that is mediated by effects of transient cerebral ischaemia during bleeding plus effects of the subarachnoid blood. Secondary effects of SAH include increased intracranial pressure, destruction of brain tissue by intracerebral haemorrhage, brain shift, and herniation, all of which contribute to pathology. Many patients survive these phenomena, but deteriorate days later from delayed cerebral ischaemia (DCI), which causes poor outcome or death in up to 30% of patients with SAH. DCI is thought to be caused by the combined effects of angiographic vasospasm, arteriolar constriction and thrombosis, cortical spreading ischaemia, and processes triggered by EBI. Treatment for DCI includes prophylactic administration of nimodipine, and current neurointensive care. Prompt recognition of DCI and immediate treatment by means of induced hypertension and balloon or pharmacological angioplasty are considered important by many physicians, although the evidence to support such approaches is limited. This Review summarizes the pathophysiology of DCI after SAH and discusses established treatments for this condition. Novel strategies--including drugs such as statins, sodium nitrite, albumin, dantrolene, cilostazol, and intracranial delivery of nimodipine or magnesium--are also discussed.

Medical Management of Cerebral Vasospasm following Aneurysmal Subarachnoid Hemorrhage: A Review of Current and Emerging Therapeutic Interventions

Cerebral vasospasm is a major source of morbidity and mortality in patients with aneurysmal subarachnoid hemorrhage (aSAH). Evidence suggests a multifactorial etiology and this concept remains supported by the assortment of therapeutic modalities under investigation. The authors provide an updated review of the literature for previous and recent clinical trials evaluating medical treatments in patients with cerebral vasospasm secondary to aSAH. Currently, the strongest evidence supports use of prophylactic oral nimodipine and initiation of triple-H therapy for patients in cerebral vasospasm. Other agents presented in this report include magnesium, statins, endothelin receptor antagonists, nitric oxide promoters, free radical scavengers, thromboxane inhibitors, thrombolysis, anti-inflammatory agents and neuroprotectants. Although promising data is beginning to emerge for several treatments, few prospective randomized clinical trials are presently available. Additionally, future investigational efforts will need to resolve discrepant definitions and outcome measures for cerebral vasospasm in order to permit adequate study comparisons. Until then, definitive recommendations cannot be made regarding the safety and efficacy for each of these therapeutic strategies and medical management practices will continue to be implemented in a wide-ranging manner.

Neuroprotective effect of Cyclosporin A on the development of early brain injury in a subarachnoid hemorrhage model: a pilot study

Cyclosporin A (CsA) has been demonstrated to be neuroprotective in ischemic and traumatic brain injuries by inhibiting mitochondrial permeability transition pore (mPTP) opening, thereby maintaining mitochondrial homeostasis and inhibiting pro-apoptotic protein release. The effects of CsA on early brain injury (EBI) after subarachnoid hemorrhage (SAH), however, have not been investigated. This study was designed to explore the effects of CsA on apoptotic signaling pathways and EBI after experimental SAH using four equal groups (n=36) of adult male SD rats, including the sham group, SAH+vehicle group, SAH+CsA2 group, and SAH+CsA10 group. The rat SAH model was induced by injection of 0.3ml non-heparinized arterial blood into the prechiasmatic cistern. In the SAH+CsA2 and SAH+CsA10 groups, a dose of 2mg/kg and 10mg/kg CsA was directly administered by intercarotid injection at 15min and again 24h after SAH induction. Cerebral tissue samples were extracted 48h after SAH. Increased expressions of Cytochrome C, apoptosis-inducing factor (AIF), and cleaved caspase-3 were observed in the cerebral cortex after SAH. Treatment with high dose (10mg/kg) CsA markedly decreased expressions of Cytochrome C, AIF, and cleaved caspase-3, and inhibited apoptosis pathways. Administration of CsA following SAH significantly ameliorated EBI, including cortical apoptosis, brain edema, blood-brain barrier (BBB) impairment, and neurobehavioral deficits. These findings suggest that early administration of CsA may ameliorate EBI and provide neuroprotection in the SAH model through potential mechanisms that include blockage of mPTP opening and inhibition of apoptotic cell death pathways.

Expression of CD137 in the cerebral artery after experimental subarachnoid hemorrhage in rats: a pilot study

Inflammation and immunity play a crucial role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). CD137 is recognized as an independent costimulatory molecule of T cells and activator of monocytes. A growing body of evidence indicates that CD137 is vital for inflammation and immunity. Therefore, this study aimed to investigate the expression of CD137 in the basilar artery in a rat SAH model and to clarify the potential role of CD137 in cerebral vasospasm. A total of 107 rats were randomly divided into four groups: control group; day 3, day 5, and day 7 groups. Day 3, day 5, and day 7 groups were all SAH groups. The animals in SAH groups were subjected to injection of autologous blood into cisterna magna twice on day 0 and day 2 and were sacrificed on days 3, 5, and 7, respectively. Cross-sectional area of basilar artery was measured and the CD137 expression was assessed by quantitative real-time PCR, Western blot and immunohistochemistry. The cross-sectional area of basilar artery was found to be 57,944±5581μm(2) in control group, 26,100±2639μm(2) in day 3, 19,723±2412μm(2) in day 5, and 28,800±2980μm(2) in day 7 group, respectively. The basilar artery exhibited vasospasm after SAH and became more severe on day 5. The elevated mRNA and protein of CD137 were detected after SAH and peaked on day 5. CD137 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in a rat experimental model of SAH. These findings indicate the possible role of CD137 in the pathogenesis of cerebral vasospasm after SAH.

Depletion of Ly6G/C(+) cells ameliorates delayed cerebral vasospasm in subarachnoid hemorrhage

BACKGROUND

The etiology of delayed cerebral vasospasm (DCV) after aneurysmal subarachnoid hemorrhage (SAH) has remained elusive. Growing evidence supports a role for inflammation in the pathogenesis of DCV. We showed that CSF neutrophils predict which patients will develop DCV.

METHODS

We evaluated a murine model of SAH to test the hypothesis that myeloid cells are required for the cerebral damage associated with DCV.

RESULTS

SAH was associated with decreased middle cerebral artery caliber on day 1 which normalized at day 3 and recurred at day 6. In addition, behavioral testing with a Barnes maze showed executive dysfunction that progressively worsened after the seventh day post hemorrhage. To test the role of innate immune responses, we administrated a myeloid cell-depleting monoclonal antibody against Ly6G/C prior to experimental SAH. Myeloid cell depletion ameliorated angiographic vasospasm measured by MCA vessel caliber and normalized behavioral testing.

CONCLUSION

Our findings support the role of Ly6G/C(+) cells in the development of DCV after SAH and suggest that immune modulation of neutrophils or other Ly6G/C(+) cells may be a strategy for the prevention of DCV.

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.

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.

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.

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.

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.

THE ADENOSINE 2A RECEPTOR AGONIST ATL-146E ATTENUATES EXPERIMENTAL POSTHEMORRHAGIC VASOSPASM

OBJECTIVE

Selective adenosine 2A receptor agonists, such as ATL-146e, are known to be potent anti-inflammatory agents devoid of systemic side effects and have been used clinically in a number of disease states. However, adenosine 2A receptor agonists have not been studied in the treatment of cerebral vasospasm after subarachnoid hemorrhage. The present study investigated the efficacy of ATL-146e in the prevention of leukocyte infiltration and attenuation of posthemorrhagic vasospasm.

METHODS

The rodent femoral artery model of vasospasm was used. Forty male Sprague-Dawley rats were randomly assigned to four different groups (vehicle, 1 ng/kg/min, 10 ng/kg/min, or 100 ng/kg/min ATL-146e administered via subcutaneous osmotic minipump). Vasospasm was evaluated at posthemorrhage Day 8 (period of peak constriction) by calculating the lumen cross-sectional area (expressed as percent change in luminal area: ratio of blood-exposed vessel to normal saline-exposed vessel) and radial wall thickness. Immunostaining with anti-CD45 monoclonal antibody to detect leukocytes was used to evaluate localized inflammation.

RESULTS

Significant vasospasm was noted in the vehicle-treated (blood-exposed) control group (78.5%, P < 0.001; expressed as a ratio of luminal area of the saline [no blood] control), but not in the ATL-146e-treated groups (lumen ratio to control: 105.0, 83.4, and 91.3% for the 1, 10, and 100 ng/kg/min groups, respectively). Additionally, infiltration of inflammatory cells was reduced significantly and radial wall thickness was decreased in the ATL-146e-treated groups compared with the vehicle-treated control group.

CONCLUSION

Selective activation of the adenosine 2A receptor with ATL-146e prevented posthemorrhagic vasospasm and reduced leukocyte infiltration in this experimental model. This agent is worthy of further investigation and lends credence to the hypothesis supporting a role for inflammation in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage.

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.

Effect of combined simvastatin and cyclosporine compared with simvastatin alone on cerebral vasospasm after subarachnoid hemorrhage in a canine model

Object

The object of this study was to determine whether the combination of cyclosporine and simvastatin could ameliorate cerebral vasospasm after subarachnoid hemorrhage (SAH) in a canine model to a greater extent than simvastatin alone.

Methods

Animals were assigned to one of three groups: control (five dogs), simvastatin alone (four), or simvastatin and cyclosporine (four). A double SAH model was used. Baseline basilar artery (BA) angiograms were obtained. These were repeated at Days 3, 7, and 10. Measurement of the BA diameter was performed.

Decreased BA diameter was seen on Day 3 in the control and simvastatin/cyclosporine group. A return to baseline diameters was seen by Day 7. An increase from baseline diameter was seen in the simvastatin group at Day 10.

Conclusions

Cyclosporine may interfere with the vasodilatory effects of simvastatin. Vasodilation greater than baseline is seen at Day 10 in the simvastatin group. The combination of simvastatin and cyclosporine does not ameliorate cerebral vasospasm in a canine model to a greater extent than simvastatin alone.

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.

Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage: An Overview of Pharmacologic Management

Cerebral vasospasm remains one of the leading causes of mortality in patients who experience a subarachnoid hemorrhage but survive the initial 24 hours. Vasospasm generally occurs 3-4 days after the initial subarachnoid hemorrhage and peaks at 5-7 days. The pathophysiology of vasospasm is poorly understood, which directly contributes to the inconsistency of management and creates a formidable challenge in clinical practice. Traditionally, hemodilution, hypervolemia, and induced hypertension (so-called triple H therapy); calcium channel blockers; and endovascular therapy have been used as either prophylactic therapy or treatment. However, management of vasospasm varies among physicians and institutions mainly because of a lack of large clinical trials and inconsistent results. Practice has been based primarily on case reports and the preference of each practitioner. Several experimental therapies have been explored; however, large, prospective, randomized controlled trials are needed to elucidate the role of these therapies.

Cerebral vasospasm after subarachnoid hemorrhage: putative role of inflammation

Cerebral vasospasm is a common, formidable, and potentially devastating complication in patients who have sustained subarachnoid hemorrhage (SAH). Despite intensive research efforts, cerebral vasospasm remains incompletely understood from both the pathogenic and therapeutic perspectives. At present, no consistently efficacious and ubiquitously applied preventive and therapeutic measures are available in clinical practice. Recently, convincing data have implicated a role of inflammation in the development and maintenance of cerebral vasospasm. A burgeoning (although incomplete) body of evidence suggests that various constituents of the inflammatory response, including adhesion molecules, cytokines, leukocytes, immunoglobulins, and complement, may be critical in the pathogenesis of cerebral vasospasm. Recent studies attempting to dissect the cellular and molecular basis of the inflammatory response accompanying SAH and cerebral vasospasm have provided a promising groundwork for future studies. It is plausible that the inflammatory response may indeed represent a critical common pathway in the pathogenesis of cerebral vasospasm pursuant to SAH. Investigations into the nature of the inflammatory response accompanying SAH are needed to elucidate the precise role(s) of inflammatory events in SAH-induced pathologies.

Up-regulation of parathyroid hormone receptor in cerebral arteries after subarachnoid hemorrhage in monkeys

OBJECTIVE

Complementary deoxyribonucleic acid array analysis was used to determine whether vasospasm after subarachnoid hemorrhage (SAH) is associated with changes in gene expression.

METHODS

Right SAHs were created in three monkeys, and the right and left middle cerebral arteries were collected 3, 7, or 14 days after SAH. Vasospasm was assessed by angiography performed on Day 0 and at tissue harvest. A complementary deoxyribonucleic acid array containing 5184 genes was used to screen for changes in gene expression by comparing the right and left middle cerebral arteries.

RESULTS

There was significant expression (greater than fivefold expression of messenger ribonucleic acid compared with internal standard control) of 537 genes (10%) in the middle cerebral arteries. One hundred sixty-four genes (31%) did not change significantly, and 373 (69%) were differentially expressed at 3, 7, or 14 days after SAH. These 373 genes changed from 1.2- to 7-fold as compared with control arteries. The most common pattern was a progressive increase with increased time after SAH. The functions of differentially expressed genes included the regulation of gene expression, cell proliferation, inflammation, membrane proteins and receptors, kinases, and phosphatases. There was a marked increase in parathyroid hormone and parathyroid hormone receptor with time after SAH. Immunoblotting demonstrated a significant increase in parathyroid hormone receptor protein.

CONCLUSION

The up-regulation of these proteins involved in vascular relaxation suggests that they may play a role in vasospasm. The progressive increase in messenger ribonucleic acids involved in the functions noted suggests that the pathogenesis of cerebral vasospasm involves cell proliferation, inflammation, and possibly smooth muscle phenotype change.

Cerebrovascular inflammation following subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage frequently results in complications including intracranial hypertension, rebleeding and vasospasm. The extravasated blood is responsible for a cascade of reactions involving release of various vasoactive and pro-inflammatory factors (several of which are purported to induce vasospasm) from blood and vascular components in the subarachnoid space. The authors review the available evidence linking these factors to the development of inflammatory lesions of the cerebral vasculature, emphasizing: 1) neurogenic inflammation due to massive release of sensory nerve neuropeptides; 2) hemoglobin from lysed erythrocytes, which creates functional lesions of endothelial and smooth muscle cells; 3) activity, expression and metabolites of lipoxygenases cyclooxygenases and nitric oxide synthases; 4) the possible role of endothelin-1 as a pro-inflammatory agent; 5) serotonin, histamine and bradykinin which are especially involved in blood-brain barrier disruption; 6) the prothrombotic and pro-inflammatory action of complement and thrombin towards endothelium; 7) the multiple actions of activated platelets, including platelet-derived growth factor production; 8) the presence of perivascular and intramural macrophages and granulocytes and their interaction with adhesion molecules; 9) the evolution, origins, and effects of pro-inflammatory cytokines, especially IL-1, TNF-alpha and IL-6. Human and animal studies on the use of anti-inflammatory agents in subarachnoid hemorrhage include superoxide and other radical scavengers, lipid peroxidation inhibitors, iron chelators, NSAIDs, glucocorticoids, and serine protease inhibitors. Many animal studies claim reduced vasospasm, but these effects are not always confirmed in human trials, where symptomatic vasospasm and outcome are the major endpoints. Despite recent work on penetrating vessel constriction, there is a paucity of studies on inflammatory markers in the microcirculation.

Expression of interleukin-1 beta in lipopolysaccharide stimulated monocytes derived from patients with aneurysmal subarachnoid hemorrhage is correlated with cerebral vasospasm

Cerebral arterial vasospasm is a frequent complication after aneurysmal subarachnoid hemorrhage (SAH). Immunological activation may affect the development of vasospasm. This study measured the cytokines released from lipopolysaccharide-stimulated monocytes of SAH patients. We measured cerebral artery diameters before and after surgery for SAH. The activation index of interleukin-1 beta (IL-1 beta), but not tumor necrosis factor-alpha (TNF-alpha), was higher in patients with symptomatic vasospasm (5.6+/-1.7; n=11) than in patients without (1.8+/-0.4; n=11) (P=0.039). Furthermore, the IL-1 beta activation index was correlated with the degree of the postoperative angiographic vasospasm (correlation coefficient=-0.66, P=0.007). Individual variation in systemic immune activation, measured by monocyte-derived IL-1 beta expression levels after stimulation, may be associated with the development of vasospasm after aneurysmal SAH.

Review of medical prevention of vasospasm after aneurysmal subarachnoid hemorrhage: a problem of neurointensive care

Cerebral vasospasm remains a devastating medical complication of aneurysmal subarachnoid hemorrhage (SAH). It is associated with high morbidity and mortality rates, even after the aneurysm has been secured surgically or radiologically. A great deal of experimental and clinical research has been conducted in an effort to find ways to prevent this complication. The literature includes extensive coverage of in vivo animal model studies of SAH and vasospasm. These experimental studies have contributed to tremendous advances in the understanding of the mechanisms leading to cerebral vasospasm. Most of the experimental settings, however, have demonstrated varying levels of ability to predict accurately what occurs in human SAH. Therefore, although animal models have been developed to test new therapies, most of the treatment effects have been shown to be less compelling when trials have been conducted in clinical settings. The interpretation of current literature is complicated further by the imprecise estimation of the incidence of cerebral vasospasm, which is due to various degrees of clinical expression, ranging from the absence of symptoms in the presence of increased blood flow velocities at transcranial Doppler or vessel diameter reduction at angiography to neurological manifestations of severe ischemic deficits. In addition, a change over time in the incidence pattern of human SAH and vasospasm, possibly related to improved surgical techniques and overall patient management, may have occurred. This topic review collects the relevant literature on clinical trials investigating prophylactic therapies for cerebral vasospasm in patients with aneurysmal SAH and emphasizes the need for large clinical trials to confirm the results derived from clinical experience. In addition, it points out some experimental therapies that may hold promise in future clinical trials to prevent the occurrence of vasospasm.

Magnesium sulfate in the management of patients with Fisher Grade 3 subarachnoid hemorrhage: a pilot study

OBJECTIVE

To evaluate the effect of magnesium sulfate (MgSO4) on the clinical course of patients with severe aneurysmal subarachnoid hemorrhage (SAH).

METHODS

Ten patients with Fisher Grade 3 aneurysmal SAH were evaluated. The patients were given a bolus as well as a constant infusion of intravenous MgSO4 up to 10 days postictus. Blood magnesium levels were obtained to adjust the daily requirement of MgSO4. The goal was to raise the serum level to 2.0 to 2.5 mmol/L or twice the baseline serum level. Daily transcranial Doppler (TCD) ultrasonography was performed on each patient, insonating both anterior cerebral and middle cerebral arteries. Further management followed standard protocols, including the use of nimodipine and hypervolemic therapy. TCD ultrasonographic findings, as well as clinical evidence of cerebral vasospasm, were documented. All patients had a 3-month assessment using the Glasgow Outcome Scale.

RESULTS

After administration of a 20 mmol MgSO4 bolus infusion and an average daily continuous infusion of 84.7 mmol, 8 of 10 patients achieved the predetermined serum magnesium levels. No adverse affects were noted during the infusions. Five patients exhibited evidence of vasospasm on TCD ultrasonography; vasospasm was severe in two patients (velocities, >200 cm/s). Three patients, including the two patients in whom TCD ultrasonography demonstrated severe vasospasm, exhibited clinical evidence of vasospasm. Two patients had a Glasgow Outcome Scale score of 3; the remainder had Glasgow Outcome Scale scores of 5.

CONCLUSION

Administration guidelines for the use of MgSO4 in aneurysmal SAH were established. A prospective double-blind placebo-controlled trial is required to establish the effectiveness of MgSO4 for treating vasospasm in aneurysmal SAH.

Effect of adenovirus-mediated nitric oxide synthase gene transfer on vasospasm after experimental subarachnoid hemorrhage

OBJECTIVE

Evidence indicates that vasospasm after subarachnoid hemorrhage (SAH) is caused in part by a decrease in the vasodilator nitric oxide (NO), which is produced mainly in endothelial cells. This study tested whether intracisternal injection of adenovirus-expressing endothelial NO synthase (eNOS) would decrease vasospasm in dogs.

METHODS

In 12 dogs, baseline cerebral angiography was performed, and then SAH was produced by two injections of blood into the cisterna magna. The dogs were randomized (n = 6/group) to intracisternal injection of adenovirus-expressing lacZ (Ad327beta-Gal) or eNOS (AdCD8-NOS), administered immediately after the first blood injection. Angiography was repeated on Day 7, and then L-arginine (50 mg) was administered intracisternally, and angiography was repeated. Cerebrospinal fluid aspirated from the cisterna magna on Days 2 and 7 was analyzed for levels of NO metabolites. The dogs were killed, and their basilar arteries were removed and studied pharmacologically. Four control dogs underwent angiography on Day 0, followed by virus injection (n = 2/group). Angiography was repeated on Day 7, and the control dogs were killed. Transgene expression was detected in tissue removed on Day 7 by histochemical staining for lacZ, by polymerase chain reaction for messenger ribonucleic acid for eNOS, and by measurement of NO metabolites in cerebrospinal fluid.

RESULTS

Angiography showed significant vasospasm in each group (Ad327beta-Gal, -54 +/- 7% reduction in basilar artery diameter; AdCD8-NOS, -53 +/- 7%), with no significant difference between groups. Injection of L-arginine caused an insignificant increase in arterial diameter in each group. In dogs without SAH, Ad327beta-Gal caused a reduction in basilar artery diameter (-13 +/- 10%, P = 0.42; paired t test), whereas injection of AdCD8-NOS caused an increase in diameter (14 +/- 16%, P = 0.77; paired t test). Histological examination and beta-galactosidase staining of dogs given injections of Ad327beta-Gal showed staining in inflammatory cells in the subarachnoid space, in the adventitia of the cerebral vessels, and in the liver and lungs. Messenger ribonucleic acid for eNOS was detected in the leptomeninges of dogs given injections of AdCD8-NOS. Under isometric tension, basilar arteries from each group demonstrated similar relaxation to L-arginine, but arteries exposed to eNOS demonstrated significantly greater relaxation to L-arginine plus tetrahydrobiopterin than arteries exposed to lacZ. Cerebrospinal fluid levels of NO and its metabolites were significantly higher in dogs treated with AdCD8-NOS than those treated with Ad327beta-Gal 2 days after SAH.

CONCLUSION

These results demonstrate that adenovirus vectors can be used to transfer genes to cells in the subarachnoid space of dogs. Enough NO can be produced in the absence of SAH to dilate the basilar artery. After SAH, however, NO plus a cofactor can dilate arteries in vitro, but not enough NO is generated in the subarachnoid space to prevent vasospasm, perhaps owing to the scavenging of NO by hemoglobin.

The prophylactic use of transluminal balloon angioplasty in patients with Fisher Grade 3 subarachnoid hemorrhage: a pilot study

OBJECT

Recent advances in neuroradiology have made it possible to dilate vasospastic human cerebral arteries after aneurysmal subarachnoid hemorrhage (SAH), but the time window is short and the success rate for reversal of delayed ischemic neurological deficits (DINDs) varies between 31% and 77%. In a dog model of vasospasm, transluminal balloon angioplasty (TBA) performed on Day 0 totally prevented the development of angiographically demonstrated narrowing on Day 7. Because the effect of preventive TBA in this animal model was better than any pharmacological treatment described previously for experimental vasospasm, the authors conducted a pilot trial in humans to assess the safety and efficacy of TBA performed within 3 days of SAH.

METHODS

The study group consisted of 13 patients with Fisher Grade 3 SAH who had a very high probability of developing vasospasm. In all patients, regardless of the site of the ruptured aneurysm, target vessels for prophylactic TBA were as follows: the internal carotid artery, A1 segment, M1 segment, and P1 segment bilaterally; the basilar artery; and one vertebral artery. Prophylactic TBA was considered satisfactory when it could be performed in at least two of the three parts of the intracranial circulation (right and/or left carotid system and/or vertebrobasilar system), and included the aneurysm-bearing part of the circulation. Of the 13 patients, none developed a DIND or more than mild vasospasm according to transcranial Doppler ultrasonography criteria. At 3 months posttreatment eight patients had made a good recovery, two were moderately disabled, and three had died; one patient died because of a vessel rupture during TBA and two elderly individuals died of medical complications associated with poor clinical condition on admission.

CONCLUSIONS

Compared with large series of patients with aneurysmal SAH reported in the literature, the results of this pilot study indicate an extremely low incidence of vasospasm and DIND after treatment with prophylactic TBA. A larger randomized study is required to determine whether prophylactic TBA is efficacious enough to justify the risks, and which vessels need to be dilated prophylactically.

Etiology of cerebral vasospasm

Cerebral vasospasm is a gradual onset and prolonged constriction of the cerebral arteries in the subarachnoid space after subarachnoid hemorrhage. The principal cause is the surrounding blood clot. The significance of vasospasm is that flow through the constricted arteries may be reduced sufficiently to cause cerebral infarction. Subarachnoid blood clot is sufficient to cause vasospasm; it does not require additional arterial injury, intracranial hypertension or brain infarction, although these elements are often coexistent. The blood released at the time of aneurysmal rupture into the alien subarachnoid environment is an extraordinarily complex mix of cellular and extracellular elements that evolves as clotting occurs; cells disintegrate; local inflammation, phagocytosis and repair take place; severe constriction alters the metabolism and structure of the arterial wall as well as the balance of vasoconstrictor and dilator substances produced by its endothelium, neurogenic network and perhaps smooth muscle cells.

Gene therapy for cerebrovascular disease

OBJECTIVE

To review the principles of and the experimental and clinical results of gene therapy for cerebrovascular disease.

METHODS

Literature review.

RESULTS

Vectors for gene transfer into the brain or into the cerebral vasculature include naked plasmid deoxyribonucleic acid, cationic liposomes, and viruses such as adenovirus, retrovirus, adeno-associated virus, and herpes simplex virus. Experiments using these vectors showed that intra- or perivascular application to systemic arteries can lead to transfection and expression of a foreign transgene in the adventitia and the endothelium. Intrathecal administration can lead to transfection and foreign transgene expression in leptomeningeal cells as well as in fibroblasts of blood vessel adventitia. Biological effects demonstrated thus far include increased nitric oxide production by transfection of cerebral arterial adventitia with adenovirus expressing nitric oxide synthase. Adenoviruses carrying foreign genes have been used to decrease neuronal damage in cerebral ischemia and to decrease blood pressure in spontaneously hypertensive rats. Vectors and therapeutic applications for gene therapy are evolving rapidly.

CONCLUSION

Gene therapy for cerebrovascular disease is likely to have clinical application in the near future and will have a major impact on neurosurgery. Neurosurgeons will need to be aware of the literature in this area.

Detection of soluble E-selectin, ICAM-1, VCAM-1, and L-selectin in the cerebrospinal fluid of patients after subarachnoid hemorrhage

OBJECT

The goal of this study was to explore whether the levels of soluble adhesion molecules were elevated in cerebrospinal fluid (CSF) after subarachnoid hemorrhage (SAH). This association was suggested by the known inflammatory response in vasospasm and the role of vascular adhesion molecules in regulating leukocytic adhesion to, and migration across, vascular endothelium.

METHODS

A prospective analysis was performed on CSF samples obtained in 17 patients who had suffered a recent aneurysmal SAH and in 16 control patients by using quantitative enzyme-linked immunosorbent assays for E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), and L-selectin. Levels of soluble forms of E-selectin (p=0.0013), ICAM-1 (p=0.0001), and VCAM-1 (p=0.048) were found to be elevated in the CSF of patients after SAH compared with levels in the CSF of norminal controls, patients with unruptured aneurysms, and patients tested months after SAH occurred. In addition, individual patients tested at the time of their initial ictus demonstrated a fall in adhesion molecule levels over time. Levels of E-selectin (p=0.044) were highest in patients who later developed moderate or severe vasospasm.

CONCLUSIONS

Adhesion molecules are known to be involved in white cell adherence to the endothelium and subsequent diapedesis and migration in which a role in initiation of tissue damage is postulated. The authors have demonstrated the elevation of three adhesion molecules, with severely elevated levels of E-selectin seen in patients who later develop vasospasm. A correlation with a role of vascular adhesion molecules in the pathogenesis of cerebral vasospasm is suggested.

Safety and efficacy of transluminal balloon angioplasty in the prevention of vasospasm in patients with Fisher Grade 3 subarachnoid hemorrhage: a pilot study

Recent advances in neuroradiology have made it possible to dilate human cerebral arteries that show vasospasm following aneurysmal subarachnoid hemorrhage (SAH), but the time window is short and the success rate for reversal of delayed ischemic neurological deficit (DIND) varies between 31% and 77%. In a canine model of vasospasm, transluminal balloon angioplasty (TBA) performed on Day 0 (the day of aneurysm rupture) has been shown to completely prevent the development of angiographically demonstrated narrowing by Day 7; this effect is better than any pharmacological treatment for vasospasm thus far described.

The authors conducted a pilot trial to assess the safety and efficacy of TBA performed within 3 days post-SAH. Twelve patients with a very high probability of developing vasospasm (Fisher Grade 3) were included. Target vessels for prophylactic TBA were the internal carotid artery, A1 segment, M1 segment, and P1 segment bilaterally, the basilar artery, and the vertebral artery.

No patient developed DIND or more than mild vasospasm, according to transcranial Doppler criteria. At 3 months, seven patients made a good recovery, two patients were moderately disabled, and three patients died; one patient died because of a vessel rupture during TBA and two older patients died of medical complications associated with an already poor clinical condition at admission.

Compared with the results of large series reported in literature of patients with aneurysmal SAH, the results of this pilot study indicate an extremely low incidence of vasospasm and DIND after patients underwent prophylactic TBA. A larger, randomized study, however, is required to determine whether prophylactic TBA is efficacious enough to justify the risks.

Monoclonal antibodies against ICAM-1 and CD18 attenuate cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

BACKGROUND AND PURPOSE

Inflammatory responses have been implicated in the elaboration of several forms of central nervous system injury, including cerebral vasospasm after subarachnoid hemorrhage (SAH). A critical event participating in such responses is the recruitment of circulating leukocytes into the inflammatory site. Two of the key adhesion molecules responsible for the attachment of leukocytes to endothelial cells are intercellular adhesion molecule-1 (ICAM-1) and the common beta chain of the integrin superfamily (CD18). This study examined the effects of monoclonal antibodies on ICAM-1 and the effects of CD18 on cerebral vasospasm after SAH.

METHODS

A rabbit model of SAH was utilized to test the influence of intracisternally administered antibodies to ICAM-1 and CD18 on cerebral vasospasm. Antibodies were administered alone or in combination, and the cross-sectional area of basilar arteries was assessed histologically on day 2 post-SAH.

RESULTS

Treatment with antibodies to ICAM-1 or CD18 inhibited vasospasm by 22% and 27%, respectively. When administered together, the attenuation of vasospasm increased to 56%. All of these effects achieved statistical significance.

CONCLUSIONS

These findings provide the first evidence that the severity of cerebral vasospasm can be attenuated using monoclonal antibodies against ICAM-1 and CD18. The results reinforce the concept that cell-mediated inflammation plays an important role in cerebral vasospasm after SAH and suggest that therapeutic targeting of cellular adhesion molecules can be of benefit in treating cerebral vasospasm.

Anticardiolipin antibody aggravates cerebral vasospasm after subarachnoid hemorrhage in rabbits

BACKGROUND AND PURPOSE

We previously reported that patients with antiphospholipid antibodies (aPLs) frequently demonstrate cerebral infarction due to cerebral vasospasm after subarachnoid hemorrhage (SAH). To examine the participation of aPLs in the pathogenesis of vasospasm after SAH, we studied the relationships of aPLs and SAH in an animal model.

METHODS

SAH was produced in 34 rabbits that received two subarachnoid injections of autologous arterial blood. The animals were divided into four experimental groups: SAH was induced in group A (n=9), intracutaneous injection of cardiolipin (CL) was performed before the induction of SAH in group B (n=5), intravenous injection of CL was performed before SAH in group C (n=12), and cyclosporin A was infused intravenously after the intravenous injection of CL and induction of SAH in group D (n=8). Enzyme-linked immunosorbent assay identifying the titer of IgG CL antibodies, neurological evaluation, cerebral angiography, and histological examination were performed in all four groups.

RESULTS

A significant elevation of anti-CL antibodies, aggravation of neurological deficit, and reduction of caliber of the basilar artery were observed in rabbits that received the intravenous immunization of CL (group C). The administration of cyclosporin A reduced the titer of anti-CL antibody, aggravation of neurological deficit, constriction of basilar artery, and the incidence of cerebral infarction (group D).

CONCLUSIONS

Anti-CL antibodies may therefore be involved in the deterioration of cerebral vasospasm after SAH.