Erythropoietin prevents delayed hemodynamic dysfunction after subarachnoid hemorrhage in a randomized controlled experimental setting

Acute Kidney Injury in Subarachnoid Hemorrhage: Exploring its Clinical Significance and Prognostic Implications

OBJECTIVES

Subarachnoid hemorrhage (SAH) from spontaneous rupture of an aneurysm is a debilitating condition with high morbidity and mortality. Patients with SAH remain understudied, particularly concerning the evaluation of incidence and consequences of subsequent acute kidney injury (AKI). In this study, we aim to explore the risk factors and outcomes of AKI in patients with SAH.

MATERIALS AND METHODS

International Classification of Diseases, 9th Edition and 10th Edition (ICD-10-CM) codes were used to query the National Inpatient Sample (NIS) for patients with a diagnosis of SAH between 2010-2019. Subgroup analysis was stratified by AKI diagnosis during the same hospitalization. AKI and non-AKI groups were assessed for baseline clinical characteristics, interventions, complications, and outcomes. Descriptive statistics, multivariate regressions, and propensity score-matching were performed using IBM SPSS 28.

NEED TO MENTION NIH-SSS RESULTS

Of 76,553 patients diagnosed with nontraumatic SAH between 2010-2019, 10,634 (13.89%) had a comorbid diagnosis of AKI. Patients with AKI were older (p<0.01) and more often obese (p < 0.01), compared to the non-AKI group. A multivariate regression found the diagnosis of AKI to be independently correlated with poor functional outcome (p<0.001), above average length of stay (p < 0.001), and in-hospital mortality (p < 0.001) when controlling for age, SAH severity, and other comorbidities.

CONCLUSIONS

This study showed significant association between AKI and adverse outcomes in SAH patients, and a correlation between AKI and heightened complication rates, poor functional outcome, extended hospital stays, and elevated mortality rates. Early detection of AKI in SAH patients is vital to enhance their chances of recovery.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Cerebral Autoregulation in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating stroke subtype with a high rate of mortality and morbidity. The poor clinical outcome can be attributed to the biphasic course of the disease: even if the patient survives the initial bleeding emergency, delayed cerebral ischemia (DCI) frequently follows within 2 weeks time and levies additional serious brain injury. Current therapeutic interventions do not specifically target the microvascular dysfunction underlying the ischemic event and as a consequence, provide only modest improvement in clinical outcome. SAH perturbs an extensive number of microvascular processes, including the “automated” control of cerebral perfusion, termed “cerebral autoregulation.” Recent evidence suggests that disrupted cerebral autoregulation is an important aspect of SAH-induced brain injury. This review presents the key clinical aspects of cerebral autoregulation and its disruption in SAH: it provides a mechanistic overview of cerebral autoregulation, describes current clinical methods for measuring autoregulation in SAH patients and reviews current and emerging therapeutic options for SAH patients. Recent advancements should fuel optimism that microvascular dysfunction and cerebral autoregulation can be rectified in SAH patients.

Evaluation of efficacy and safety of endovascular coiling for patients with aneurysmal subarachnoid hemorrhage: A protocol for systematic review and meta-analysis

BACKGROUND

There is an elevated risk of rebleeding when the aneurysm is left untreated in patients diagnosed with aneurysmal subarachnoid hemorrhage (SAH). Occlusion of the lumen of the aneurysm using endovascular coiling is a common method to prevent rebleeding by occluding the aneurysm. This study aims to evaluate the efficacy and safety of endovascular coiling in patients with aneurysmal SAH.

METHODS

A systematic search for relevant articles will be performed in 4 English electronic databases, including MEDLINE (from 1966 to October 2020), EMBASE (from 1980 to October 2020), the Cochrane Library (from 2020, issue 10), Scopus (from 1823 to October 2020), and 3 Chinese electronic databases, including Chinese Biomedical Literature Database (from 1995 to October 2020), WanFang (last searched October 2020), and China National Knowledge Infrastructure (last searched October 2020). This study will comprise randomized controlled trials (RCTs) that evaluate the effectiveness and safety of using endovascular coiling in the treatment of aneurysmal SAH. The articles in the databases will be independently screened by 2 authors to select potential studies, extract data, and evaluate the bias risk in the selected studies. This study will use suitable statistical methods to merge result data.

RESULTS

The results of this study will be useful in determining the efficacy and safety of endovascular coiling for treating patients with aneurysmal SAH.

CONCLUSION

The findings of this study will summarize the most recent evidence on the effectiveness and safety of using endovascular coiling to treat aneurysmal SAH.

ETHICS AND DISSEMINATION

The present work does not involve any humans or animals; therefore, ethical approval is not needed.

SYSTEMATIC REVIEW REGISTRATION

December 2, 2020.osf.io/yj4gq (https://osf.io/yj4gq/).

Vasomodulatory effects of the angiotensin II type 1 receptor antagonist losartan on experimentally induced cerebral vasospasm after subarachnoid haemorrhage

BACKGROUND

Cerebral vasospasm following subarachnoid haemorrhage (SAH) remains one of the major factors contributing to poor overall patient outcome. Prostaglandin F2-alpha (PGF2a) induces vasoconstriction. After SAH, PGF2a leads to cerebral inflammation and enhanced vasoconstriction, resulting in cerebral vasospasm. Losartan is already known to have beneficial effects in stroke models and also on several cerebral inflammatory processes. Therefore, the aim of the study was to analyse the effect of losartan on PGF2a-enhanced vasoconstriction after SAH.

METHODS

To investigate the effect of losartan on PGF2a-enhanced vasoconstriction after SAH, cerebral vasospasm was induced by a double-haemorrhage model. Rats were killed on day 3 and 5 after SAH followed by measurement of the isometric force of basilar artery ring segments in an organ bath.

RESULTS

PGF2a induced a dose-dependent contraction. After pre-incubation with losartan, the maximum contraction (E_max) for sham-operated animals was significantly lowered [E_max 6% in losartan 3 × 10^-4 molar (M) vs. 56% without losartan]. Also, after induced SAH, PGF2a induced no vasoconstriction in pre-incubated vessels with losartan 3 × 10^-4 M on day 3 (d3) as well as on day 5 (d5). For the vasorelaxative investigations, vessel segments were pre-incubated with PFG2a. Cumulative application of losartan completely resolved the pre-contraction in sham-operated animals (non SAH: 95% relaxation). After SAH, losartan not only resolved the pre-contraction (d5: 103%), but also exceeded the pre-contraction (d3: 119%). Therefore, a statistically significantly increased and earlier relaxation was calculated for all losartan concentrations [E_max (d3/d5) and pD₂ (d3/d5)] compared with the solvent control group.

CONCLUSION

In a physiological and pathophysiological setup, losartan reduces a PGF2-induced vasoconstriction and reverses a PGF2a-precontraction completely. This fact can be integrated in pushing forward further concepts trying to antagonise/prevent cerebral vasospasm after SAH.

Ethyl pyruvate attenuates delayed experimental cerebral vasospasm following subarachnoid haemorrhage in rats: possible role of JNK pathway

The pathophysiology of delayed cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is multifaceted and involves endothelial apoptosis and inflammation. Ethyl pyruvate (EP) could attenuate early brain injury following SAH via anti-inflammation and inhibition of the c-Jun N-terminal kinase (JNK) signalling pathway. However, the role of EP in the delayed CVS has yet to be determined. In this study, we examined the effect of EP on endothelial apoptosis and inflammation and explore possible signalling pathways. We found that EP could significantly attenuate the delayed CVS. Possible mechanisms include a decrease in the endothelial cell apoptosis of the basilar artery and alleviation of endothelial inflammation. The JNK signalling pathway may play an important role in the neuroprotective effects of EP on delayed CVS. The results suggest that EP may be a possible therapy for delayed CVS, and the JNK signalling pathway should be targeted for therapeutic purposes in the future.

The pathophysiology of delayed cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is multifaceted and involves endothelial apoptosis and inflammation.

Levosimendan, a new therapeutic approach to prevent delayed cerebral vasospasm after subarachnoid hemorrhage?

BACKGROUND

Under physiological cerebral conditions, levosimendan, a calcium-channel sensitizer, has a dose-dependent antagonistic effect on prostaglandin F2alpha (PGF)-induced vasoconstriction. This circumstance could be used in antagonizing delayed cerebral vasospasm (dCVS), one of the main complications after subarachnoid hemorrhage (SAH), leading to delayed cerebral ischemia and ischemic neurological deficits. Data already exist that identified neuroprotective effects of levosimendan in a traumatic brain injury model and additionally, it has been proven that this compound prevents narrowing of the basilar artery (BA) luminal area after SAH in an in vitro rabbit model. Takotsubo cardiomyopathy, a severe ventricular dysfunction, is also a well-known complication after SAH, associated with pulmonary edema and prolonged intubation.

METHODS

The polypeptide endothelin-1 (ET-1) plays a key role in the development of dCVS after SAH. Therefore, the aim of the present investigation was to detect functional interactions between the calcium-sensitizing and the ET-1-dependent vasoconstriction after experimental-induced SAH; interactions between levosimendan and a substrate-specific vasorelaxation in the BA were also examined. It was reviewed whether levosimendan has a beneficial influence on endothelin(A) and/or endothelin(B₁) receptors (ET-(A) and ET-(B₁) receptors) in cerebral vessels after SAH. We also examined whether this drug could have antagonistic effects on a PGF-induced vasoconstriction.

RESULTS

Under treatment with levosimendan after SAH, the endothelin system seems to be affected. The ET-1-induced contraction is decreased, not significantly. In addition, we detected changes in the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway. Preincubation with levosimendan causes a modulatory effect on the ET-(B₁) receptor-dependent vasorelaxation. It induces an upregulation of the NO-cGMP pathway with a significantly increased relaxation. Even after PGF-induced precontraction a dose-dependent relaxation was registered, which was significantly higher (E_max) and earlier (pD₂) compared to the concentration-effect curve without levosimendan.

CONCLUSIONS

After experimental-induced dCVS, levosimendan seems to restore the well-known impaired function of the vasorelaxant ET-(B₁) receptor. Levosimendan also reversed the PGF-induced contraction dose-dependently. Both of these mechanisms could be used for antagonizing dCVS in patients suffering SAH. Levosimendan could even be used additionally in treating patients developing takotsubo cardiomyopathy.

Aneurysmal Subarachnoid Hemorrhage and Neuroinflammation: A Comprehensive Review

Aneurysmal subarachnoid hemorrhage (SAH) can lead to devastating outcomes including vasospasm, cognitive decline, and even death. Currently, treatment options are limited for this potentially life threatening injury. Recent evidence suggests that neuroinflammation plays a critical role in injury expansion and brain damage. Red blood cell breakdown products can lead to the release of inflammatory cytokines that trigger vasospasm and tissue injury. Preclinical models have been used successfully to improve understanding about neuroinflammation following aneurysmal rupture. The focus of this review is to provide an overview of how neuroinflammation relates to secondary outcomes such as vasospasm after aneurysmal rupture and to critically discuss pharmaceutical agents that warrant further investigation for the treatment of subarachnoid hemorrhage. We provide a concise overview of the neuroinflammatory pathways that are upregulated following aneurysmal rupture and how these pathways correlate to long-term outcomes. Treatment of aneurysm rupture is limited and few pharmaceutical drugs are available. Through improved understanding of biochemical mechanisms of injury, novel treatment solutions are being developed that target neuroinflammation. In the final sections of this review, we highlight a few of these novel treatment approaches and emphasize why targeting neuroinflammation following aneurysmal subarachnoid hemorrhage may improve patient care. We encourage ongoing research into the pathophysiology of aneurysmal subarachnoid hemorrhage, especially in regards to neuroinflammatory cascades and the translation to randomized clinical trials.

Multimodal MRI characterization of experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is associated with significant morbidity and mortality. We implemented an in-scanner rat model of mild SAH in which blood or vehicle was injected into the cistern magna, and applied multimodal MRI to study the brain prior to, immediately after (5min to 4h), and upto 7days after SAH. Vehicle injection did not change arterial lumen diameter, apparent diffusion coefficient (ADC), T2, venous signal, vascular reactivity to hypercapnia, or foot-fault scores, but mildly reduce cerebral blood flow (CBF) up to 4h, and open-field activity up to 7days post injection. By contrast, blood injection caused: (i) vasospasm 30min after SAH but not thereafter, (ii) venous abnormalities at 3h and 2days, delayed relative to vasospasm, (iii) reduced basal CBF and to hypercapnia 1-4h but not thereafter, (iv) reduced ADC immediately after SAH but no ADC and T2 changes on days 2 and 7, and (v) reduced open-field activities in both SAH and vehicle animals, but no significant differences in open-field activities and foot-fault tests between groups. Mild SAH exhibited transient and mild hemodynamic disturbances and diffusion changes, but did not show apparent ischemic brain injury nor functional deficits.

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.

Aneurysmal subarachnoid hemorrhage: pathobiology, current treatment and future directions

Aneurysmal subarachnoid hemorrhage is the most devastating form of stroke. Many pathological mechanisms ensue after cerebral aneurysm rupture, including hydrocephalus, apoptosis of endothelial cells and neurons, cerebral edema, loss of blood-brain barrier, abnormal cerebral autoregulation, microthrombosis, cortical spreading depolarization and macrovascular vasospasm. Although studied extensively through experimental and clinical trials, current treatment guidelines to prevent delayed cerebral ischemia is limited to oral nimodipine, maintenance of euvolemia, induction of hypertension if ischemic signs occur and endovascular therapy for patients with continued ischemia after induced hypertension. Future investigations will involve agents targeting vasodilation, anticoagulation, inhibition of apoptosis pathways, free radical neutralization, suppression of cortical spreading depolarization and attenuation of inflammation.

Rat cisterna magna double-injection model of subarachnoid hemorrhage - background, advantages/limitations, technical considerations, modifications, and outcome measures

The pathophysiological changes following aneurysmal subarachnoid hemorrhage (SAH) are commonly divided into early consequences (developing shortly after the bleeding) and delayed consequences of the bleeding. The development of delayed injury mechanisms, e.g., reduced cerebral blood flow (CBF) caused by cerebral vasospasm (CVS) or development of delayed ischemic neurological deficits (DIND), seem mainly to depend on the amount and duration of the subarachnoid blood clot. CVS may progress to cerebral ischemia and infarction, and therefore lead to delayed neurological deterioration. The rat double-hemorrhage model reproduces the time course of the delayed pathophysiological consequences of CVS, which imitates the clinical setting more precisely than other rodent models. Furthermore, this model is adjustable via various technical considerations or modifications. Therefore, the double-hemorrhage model is predisposed to be used to mimic the delayed effects of SAH and to investigate the use of drugs on morphological ischemic, functional, and vasospastic effects.