Inflammation, vasospasm, and brain injury after subarachnoid hemorrhage

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.

Predictive value of cerebrovascular time constant for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Time constant of the cerebral arterial bed (τ) is a transcranial Doppler (TCD) based metric that is expected to quantify the transit time of red blood cells from the insonation point to the arteriole-capillary boundary during a cardiac cycle. This study aims to assess the potential of τ as an early predictor of delayed cerebral ischemia (DCI). Consecutive patients (56 ± 15 years) treated for aneurysmal subarachnoid haemorrhage were included in the study. τ was assessed through a modelling approach that involved simultaneous recordings of arterial blood pressure and cerebral blood flow velocity (CBFV) from TCD's first recordings. 71 patients were included. 17 patients experienced DCI. τ was significantly shorter in patients who later developed DCI: 187 ± 64 ms vs. 249 ± 184 ms; p = 0.040 with moderate effect size (rG = 0.24). Logistic regression showed that there was a significant association between increased CBFV, shortened τ, and the development of DCI (χ2 = 11.54; p = 0.003) with AUC for the model 0.75. Patients who had both shortened τ and increased CBFV were 20 times more likely to develop DCI (OR = 20.4 (2.2-187.7)). Our results suggest that early alterations in τ are associated with DCI after aSAH. The highest performance of the model including both CBFV and τ may suggest the importance of both macrovascular and microvascular changes assessment.

A Mediation Analysis of the Association Between Systemic Inflammation Response Index, in-Hospital Complications, and Poor Long-Term Functional Outcomes in Patients with Aneurysmal Subarachnoid Hemorrhage: Insights from a Large Prospective Cohort Study

Purpose

Early systemic inflammatory changes are increasingly recognized as factors influencing outcomes after aneurysmal subarachnoid hemorrhage (aSAH). Systemic inflammation response index (SIRI), an inflammation biomarker, was thought to be associated with adverse outcomes in many other diseases. However, in aSAH, research on SIRI remains limited. Thus, our objective was to investigate the association between SIRI and poor long-term functional outcomes while evaluating the mediating role of in-hospital complications in this association.

Patients and Methods

SIRI was defined as neutrophil count × monocyte count/lymphocyte count. Patients were categorized according to SIRI quartiles. Stabilized inverse probability of treatment weighting (sIPTW) was utilized to minimize group differences. The association between SIRI and in-hospital complications as well as poor 90-day functional outcomes (mRS 3-6) was estimated by multivariable logistic regression analyses. Mediation analysis was performed to investigate the relationship between SIRI and poor functional outcomes mediated by in-hospital complications.

Results

A total of 650 patients were prospectively included. After sIPTW, compared to the lowest quartile, an elevated SIRI was associated with delayed cerebral ischemia (DCI) (OR 2.12, 95% CI 1.20-3.74), post-operative pneumonia (POP) (OR 2.16, 95% CI 1.29-3.62) and poor 90-day functional outcomes (OR 3.03, 95% CI 1.55-5.91). In-hospital complications including DCI (mediation proportion, 18.18% before sIPTW and 20.0% after sIPTW) and POP (mediation proportion, 18.18% before sIPTW and 26.7% after sIPTW) partially mediated the association between SIRI and poor 90-day functional outcomes. Mediation analysis yielded comparable results in subgroups stratified by age and sex.

Conclusion

In this study, SIRI was associated with poor long-term functional outcomes in aSAH, which was partially mediated by DCI and POP with a mediation proportion exceeding 18%. Our findings might underscore the potential utility of SIRI in prompting physicians to address systemic inflammatory status timely to prevent in-hospital complications, including DCI and POP, and ultimately improve long-term functional outcomes.

Intestinal flora influences the progression of subarachnoid hemorrhage by affecting peripheral and central inflammatory pathways

Subarachnoid hemorrhage (SAH) is a debilitating condition that leaves survivors with neurological disability for the rest of their lives. No effective treatment for early brain injury (EBI) has been developed. Gut microbiome (GM) impact the host immune system and can influence disease processes in several organs, including the brain. However, it remains unclear whether the GM has an impact on the outcome of SAH brain injury. Here, we wondered whether microbiota could relieve the injury. We changed the microbiota of 8-week-old male rats by administering antibiotic-containing water for 2 weeks. Composition of the GM was profiled by using 16S rRNA. We induced SAH by puncture the internal carotid artery of control rats and rats with altered GM. Additionally, we studied inflammatory cells using HE stains, Intestinal lymphocyte flow cytometry, and Neuroinflammatory factor WB. SAH was significantly averted by alterations in GM using antibiotics. The altered GM significantly increased the intestinal and intracranial inflammation after SAH. This was manifested by Mosin (MSN) inflammatory cytokines. Our findings demonstrated that the brain injury following SAH is associated with GM.

Validation of a Simplified Model for Subarachnoid Hemorrhage in Mice

BACKGROUND

Subarachnoid hemorrhage (SAH) represents a severe injury to the brain and is associated with a high mortality (40%). Several experimental SAH models are described in the literature requiring specialized equipment and a high degree of surgical expertise. Our goal was to validate a simplified, cost-effective model to permit future studies of SAH.

METHODS

SAH was induced by injection of homologous blood into the cisterna magna. Perfusion-fixation then perfusion of gelatinous India ink was performed. Brains and brainstems were collected and imaged for analysis of cerebral vasospasm. Triphenyl tetrazolium chloride (TTC) staining was used to analyze brain tissue cell death 24 hours following stroke. A composite neuroscore was utilized to assess SAH-related neurologic deficits.

RESULTS

Anterior cerebral artery and basilary artery diameters were significantly reduced at 24 hours post SAH induction. Middle cerebral artery diameter was also reduced; however, the results were not significant. TTC staining showed no infarcted tissue. Neuroscores were significantly lower in the SAH mice, indicating the presence of functional deficits.

CONCLUSIONS

This simplified model of SAH elicits pathological changes consistent with those described for more complex models in the literature. Therefore, it can be used in future preclinical studies examining the pathophysiology of SAH and novel treatment options.

Advances in biomarkers for vasospasm - Towards a future blood-based diagnostic test

Objective

Cerebral vasospasm and the resultant delayed cerebral infarction is a significant source of mortality following aneurysmal SAH. Vasospasm is currently detected using invasive or expensive imaging at regular intervals in patients following SAH, thus posing a risk of complications following the procedure and financial burden on these patients. Currently, there is no blood-based test to detect vasospasm.

Methods

PubMed, Web of Science, and Embase databases were systematically searched to retrieve studies related to cerebral vasospasm, aneurysm rupture, and biomarkers. The study search dated from 1997 to 2022. Data from eligible studies was extracted and then summarized.

Results

Out of the 632 citations screened, only 217 abstracts were selected for further review. Out of those, only 59 full text articles met eligibility and another 13 were excluded.

Conclusions

We summarize the current literature on the mechanism of cerebral vasospasm and delayed cerebral ischemia, specifically studies relating to inflammation, and provide a rationale and commentary on a hypothetical future bloodbased test to detect vasospasm. Efforts should be focused on clinical-translational approaches to create such a test to improve treatment timing and prediction of vasospasm to reduce the incidence of delayed cerebral infarction.

The impact of pre-ictal statin use on vasospasm and outcome in aneurysmal subarachnoid hemorrhage

BACKGROUND

Pleiotropic effects of statins may be beneficial in alleviating cerebral vasospasm (VS) and improving outcome after aneurysmal subarachnoid hemorrhage (aSAH). Initiation of statin treatment at aSAH is not recommended; however, the effect of pre-ictal and continued statin use is not fully investigated.

METHODS

Retrospective study comparing aSAH patients admitted in 2012 to 2021 with pre-ictal statin use versus those not using statins. Patient entry variables, radiological/sonological VS, symptomatic VS, and radiologically documented delayed cerebral ischemia (DCI) were registered. Outcome was scored in terms of mortality, modified Rankin score, Glasgow outcome score extended, and levels of fatigue. Patients were compared on group level and in a case-control design.

RESULTS

We included 961 patients, with 204 (21.2%) statin users. Statin users were older and had more often hypertension. Severe radiological/sonological VS, symptomatic VS, and DCI were less frequent in statin users, and their length of stay was shorter. Mortality, functional outcome, and levels of fatigue were similar in both groups. When analyzing 89 pairs of statin users and non-statin users matched for age, aSAH severity, gender, and hypertension, we confirmed decreased radiological/sonological and symptomatic VS as well as shorter length of stay in statin users. They also had more often a favorable functional outcome and lower levels of fatigue.

CONCLUSIONS

Patients with pre-ictal and continued use of statins have a reduced occurrence of radiological/sonological and symptomatic VS, shorter length of stay, and more often favorable functional outcome, whereas mortality is similar to non-statin users. Even though larger multicenter studies with common, strict protocols for prevention, diagnosis, and treatment of vasospasm are needed to finally establish the value of statins in aSAH, continuation of pre-ictal statin use seems worthwhile.

Circulating Extracellular Vesicles in Subarachnoid Hemorrhage Patients: Characterization and Cellular Effects

Circulating extracellular vesicles (EVs) may play a pathophysiological role in the onset of complications of subarachnoid hemorrhage (SAH), potentially contributing to the development of vasospasm (VP). In this study, we aimed to characterize circulating EVs in SAH patients and examine their effects on endothelial and smooth muscle cells (SMCs). In a total of 18 SAH patients, 10 with VP (VP), 8 without VP (NVP), and 5 healthy controls (HC), clinical variables were recorded at different time points. EVs isolated from plasma samples were characterized and used to stimulate human vascular endothelial cells (HUVECs) and SMCs. We found that EVs from SAH patients expressed markers of T-lymphocytes and platelets and had a larger size and a higher concentration compared to those from HC. Moreover, EVs from VP patients reduced cell viability and mitochondrial membrane potential in HUVECs and increased oxidants and nitric oxide (NO) release. Furthermore, EVs from SAH patients increased intracellular calcium levels in SMCs. Altogether, our findings reveal an altered pattern of circulating EVs in SAH patients, suggesting their pathogenic role in promoting endothelial damage and enhancing smooth muscle reactivity. These results have significant implications for the use of EVs as potential diagnostic/prognostic markers and therapeutic tools in SAH management.

Combined stent retriever angioplasty and continuous intra-arterial nimodipine infusion as salvage therapy for cerebral vasospasm and delayed cerebral ischemia after subarachnoid hemorrhage: illustrative case

BACKGROUND

Delayed cerebral ischemia (DCI) and cerebral vasospasm (CV) are severe complications of spontaneous subarachnoid hemorrhage (SAH) contributing to an inferior outcome. Rescue therapies include intra-arterial balloon angioplasty and repetitive and finally continuous intra-arterial nimodipine infusion.

OBSERVATIONS

In the presented case, a young female patient with fulminant refractory DCI and CV, despite induced hypertension and nimodipine application, was treated with three-vessel continuous intra-arterial infusion and additional repetitive angioplasty of the basilar and middle cerebral arteries using a stent retriever, leading to a good clinical outcome. Additional stent retriever dilatation to continuous intra-arterial nimodipine application in three vessel territories may represent a further escalation step in the rescue therapy for severe CV and DCI after SAH. Montreal Cognitive Assessment and SF-36 testing showed satisfactory results 3 months after initial treatment with intra-arterial nimodipine catheters in three vessel territory circulations and additional stent retriever vasodilation of severe CV.

LESSONS

We report a unique rescue strategy involving implantation of an additional intra-arterial catheter into the vertebral artery and repetitive stent retriever dilatations of the middle cerebral and basilar arteries as an extra therapy for continuous intra-arterial nimodipine vaspospasmolytic therapy in three vessel territories, resulting in a very good clinical outcome.

The Role of Early Serum Biomarkers and Clinical Rating Scales in the Prediction of Delayed Cerebral Ischaemia and Short-Term Outcome after Aneurysmal Subarachnoid Haemorrhage: Single Centre Experience

Considering the variety of complications that arise after aneurysmal subarachnoid haemorrhage (aSAH) and the complex pathomechanism of delayed cerebral ischaemia (DCI), the task of predicting the outcome assumes a profound complexity. Therefore, there is a need to develop early predictive and decision-making models. This study explores the effect of serum biomarkers and clinical scales on patients' outcomes and their interrelationship with DCI and systemic complications in aSAH. This was a retrospective analysis including aSAH patients admitted to the Wroclaw University Hospital (Wrocław, Poland) from 2011 to 2020. A good outcome was defined as a modified Rankin Scale (mRS) score of 0-2. The prediction of the development of DCI and poor outcome was conducted using logistic regression as a standard model (SM) and random forest as a machine learning method (ML). A cohort of 174 aSAH patients were included in the analysis. DCI was diagnosed in 79 (45%) patients. Significant differences between patients with poor vs. good outcome were determined from their levels of albumin (31 ± 7 vs. 35 ± 5 (g/L); p < 0.001), D-dimer (3.0 ± 4.5 vs. 1.5 ± 2.8 (ng/mL); p < 0.001), procalcitonin (0.2 ± 0.4 vs. 0.1 ± 0.1 (ng/mL); p < 0.001), and glucose (169 ± 69 vs. 137 ± 48 (nmol/L); p < 0.001). SM for DCI prediction included the Apache II scale (odds ratio [OD] 1.05; 95% confidence interval [CI] 1.00-1.09) and albumin level (OD 0.88; CI 0.82-0.95). ML demonstrated that low albumin level, high Apache II scale, increased D-dimer and procalcitonin levels had the highest predictive values for DCI. The integration of clinical parameters and scales with a panel of biomarkers may effectively facilitate the stratification of aSAH patients, identifying those at high risk of secondary complications and poor outcome.

The effect of induced hypertension in aneurysmal subarachnoid hemorrhage: A narrative review

Aneurysmal subarachnoid hemorrhage ‎(aSAH) ‎accounts for 2-5% of all strokes, and 10%-15% of ‎aSAH patients will not survive until hospital admission. Induced hypertension (IH) is an emerging therapeutic option being used for the treatment of vasospasm in ‎aSAH. For patients with cerebral vasospasm (CVS) consequent to SAH, IH is implemented to increase systolic blood pressure (SBP) in order to optimize cerebral blood flow (CBF) and prevent delayed cerebral ischemia (DCI). Prophylactic use of IH has been associated with the development of vasospasm and cerebral ischemia in SAH patients. Various trials have defined several different parameters to help clinicians decide when to initiate IH in a SAH patient. However, there is insufficient evidence to recommend therapeutic IH in aSAH due to the possible serious complications like myocardial ischemia, development of posterior reversible encephalopathy syndrome (PRES), pulmonary edema, and even rupture of another unsecured aneurysm. This narrative review showed the favorable impact of IH therapy on aSAH patients; however, it is crucial to conduct further clinical and molecular experiments to shed more light on the effects of IH in aSAH.

Systemic Inflammation after Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is one of the most severe neurological disorders, with a high mortality rate and severe disabling functional sequelae. Systemic inflammation following hemorrhagic stroke may play an important role in mediating intracranial and extracranial tissue damage. Previous studies showed that various systemic inflammatory biomarkers might be useful in predicting clinical outcomes. Anti-inflammatory treatment might be a promising therapeutic approach for improving the prognosis of patients with aSAH. This review summarizes the complicated interactions between the nervous system and the immune system.

Anti-Inflammatory Drug Therapy in Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis of Prospective Randomized and Placebo-Controlled Trials

Emerging evidence suggests that neuroinflammation may play a potential role in aneurysmal subarachnoid hemorrhage (aSAH). We aim to analyze the influence of anti-inflammatory therapy on survival and outcome in aSAH. Eligible randomized placebo-controlled prospective trials (RCTs) were searched in PubMed until March 2023. After screening the available studies for inclusion and exclusion criteria, we strictly extracted the main outcome measures. Dichotomous data were determined and extracted by odds ratio (OR) with 95% confidence intervals (CIs). Neurological outcome was graded using the modified Rankin Scale (mRS). We created funnel plots to analyze publication bias. From 967 articles identified during the initial screening, we included 14 RCTs in our meta-analysis. Our results illustrate that anti-inflammatory therapy yields an equivalent probability of survival compared to placebo or conventional management (OR: 0.81, 95% CI: 0.55-1.19, p = 0.28). Generally, anti-inflammatory therapy trended to be associated with a better neurologic outcome (mRS ≤ 2) compared to placebo or conventional treatment (OR: 1.48, 95% CI: 0.95-2.32, p = 0.08). Our meta-analysis showed no increased mortality form anti-inflammatory therapy. Anti-inflammatory therapy in aSAH patients tends to improve the neurological outcome. However, multicenter, rigorous, designed, prospective randomized studies are still needed to investigate the effect of fighting inflammation in improving neurological functioning after aSAH.

Ravoxertinib Improves Long-Term Neurologic Deficits after Experimental Subarachnoid Hemorrhage through Early Inhibition of Erk1/2

Extracellular signal-regulated kinase 1 and 2 (Erk1/2) signaling has been shown to be involved in brain injury after subarachnoid hemorrhage (SAH). A first-in-human phase I study reported that ravoxertinib hydrochloride (RAH), a novel Erk1/2 inhibitor, has an acceptable safety profile and pharmacodynamic effects. Here, we showed that the level of Erk1/2 phosphorylation (p-Erk1/2) was significantly increased in the cerebrospinal fluid (CSF) of aneurysmal subarachnoid hemorrhage (aSAH) patients who developed poor outcomes. In a rat SAH model that was produced by the intracranial endovascular perforation method, western blot observed that the level of p-Erk1/2 was also increased in the CSF and basal cortex, showing a similar trend with aSAH patients. Immunofluorescence and western blot indicated that RAH treatment (i.c.v injection, 30 min post-SAH) attenuates the SAH-induced increase of p-Erk1/2 at 24 h in rats. RAH treatment can improve experimental SAH-induced long-term sensorimotor and spatial learning deficits that are evaluated by the Morris water maze, rotarod test, foot-fault test, and forelimb placing test. Moreover, RAH treatment attenuates neurobehavioral deficits, the blood-brain barrier damage, and cerebral edema at 72 h after SAH in rats. Furthermore, RAH treatment decreases the SAH-elevated apoptosis-related factor active caspase-3 and the necroptosis-related factor RIPK1 expression at 72 h in rats. Immunofluorescence analysis showed that RAH attenuated neuronal apoptosis but not neuronal necroptosis in the basal cortex at 72 h after SAH in rats. Altogether, our results suggest that RAH improves long-term neurologic deficits through early inhibition of Erk1/2 in experimental SAH.

Neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios and prognosis after aneurysmal subarachnoid hemorrhage: a cohort study

BACKGROUND

 Subarachnoid hemorrhage (SAH) prognosis remains poor. Vasospasm mechanism might be associated with inflammation. Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been studied as inflammation markers and prognostic predictors.

OBJECTIVE

 We aimed to investigate NLR and PLR in admission as predictors of angiographic vasospasm and functional outcome at 6 months.

METHODS

 This cohort study included consecutive aneurysmal SAH patients admitted to a tertiary center. Complete blood count was recorded at admission before treatment. White blood cell count, neutrophil count, lymphocyte count, platelet count, NLR, and PLR were collected as independent variables. Vasospasm occurrence-modified Rankin scale (mRS), Glasgow outcome scale (GOS), and Hunt-Hess score at admission and at 6 months were recorded as dependent variables. Multivariable logistic regression models were used to adjust for potential confounding and to assess the independent prognostic value of NLR and PLR at admission.

RESULTS

 A total of 74.1% of the patients were female, with mean age of 55.6 ± 12.4 years. At admission, the median Hunt-Hess score was 2 (interquartile range [IQR] 1), and the median mFisher was 3 (IQR 1). Microsurgical clipping was the treatment for 66.2% of the patients. Angiographic vasospasm incidence was 16.5%. At 6 months, the median GOS was 4 (IQR 0.75), and the median mRS was 3 (IQR 1.5). Twenty-one patients (15.1%) died. Neutrophil-to-lymphocyte ratio and PLR levels did not differ between favorable and unfavorable (mRS > 2 or GOS < 4) functional outcomes. No variables were significantly associated with angiographic vasospasm.

CONCLUSION

 Admission NLR and PLR presented no value for prediction of functional outcome or angiographic vasospasm risk. Further research is needed in this field.

Compartmental Cerebrospinal Fluid Events Occurring after Subarachnoid Hemorrhage: An "Heparin Oriented" Systematic Review

Subarachnoid hemorrhage (SAH) represents a severe acute event with high morbidity and mortality due to the development of early brain injury (EBI), secondary delayed cerebral ischemia (DCI), and shunt-related hydrocephalus. Secondary events (SSE) such as neuroinflammation, vasospasm, excitotoxicity, blood-brain barrier disruption, oxidative cascade, and neuronal apoptosis are related to DCI. Despite improvement in management strategies and therapeutic protocols, surviving patients frequently present neurological deficits with neurocognitive impairment. The aim of this paper is to offer to clinicians a practical review of the actually documented pathophysiological events following subarachnoid hemorrhage. To reach our goal we performed a literature review analyzing reported studies regarding the mediators involved in the pathophysiological events following SAH occurring in the cerebrospinal fluid (CSF) (hemoglobin degradation products, platelets, complement, cytokines, chemokines, leucocytes, endothelin-1, NO-synthase, osteopontin, matricellular proteins, blood-brain barrier disruption, microglia polarization). The cascade of pathophysiological events secondary to SAH is very complex and involves several interconnected, but also distinct pathways. The identification of single therapeutical targets or specific pharmacological agents may be a limited strategy able to block only selective pathophysiological paths, but not the global evolution of SAH-related events. We report furthermore on the role of heparin in SAH management and discuss the rationale for use of intrathecal heparin as a pleiotropic therapeutical agent. The combination of the anticoagulant effect and the ability to interfere with SSE theoretically make heparin a very interesting molecule for SAH management.

Post-Intensive Care Syndrome in Patients Suffering From Acute Subarachnoid Hemorrhage: Results From an Outpatient Post-ICU Aftercare Clinic

Introduction Survivors of an acute subarachnoid hemorrhage (aSAH) may suffer from a long-term neurological disability, cognitive impairment, anxiety, and depression, which can also be related to post-intensive care syndrome (PICS). The aim of this study was to examine the prevalence of PICS symptoms in post-intensive care (ICU) aftercare aSAH patients. Methods We conducted an observational cohort study in aSAH patients from a post-ICU aftercare clinic (ICU-AC). PICS symptoms were evaluated using the Impact of Event Scale-Revised (IES-R), Hospital Anxiety and Depression Scale (HADS), and a medical questionnaire for physical and cognitive functioning. Results A total of 110 patients were included. The prevalence of anxiety and depressive symptoms was 23.6% and 19.1%, respectively. Post-traumatic stress disorder (PTSD) was seen in 26.4%. Cognitive complaints were lack of concentration (63.6%), short-term memory loss (45.8%), and reduced speed of thinking (60.9%). The most reported physical complaints were fatigue (73.6%), limitations in daily activity (72.7%), muscle weakness (41.8%), pain (36.4%), and weight loss (30.9%). PICS symptoms related to all three domains were present in 30% of patients. Conclusion The prevalence of PICS in patients after aSAH is high. Even in patients without aSAH-related neurological impairment who were discharged home, a high prevalence of PICS symptoms was reported. Early screening for PICS should comprise all three domains and is important to facilitate a better tailored rehabilitation of these patients.

Peripheral eosinophil trends and clinical outcomes after non-traumatic subarachnoid hemorrhage

Background/objective

Uncontrolled systemic inflammation after non-traumatic subarachnoid hemorrhage (SAH) is associated with worse outcomes. Changes in the peripheral eosinophil count have been linked to worse clinical outcomes after ischemic stroke, intracerebral hemorrhage, and traumatic brain injury. We aimed to investigate the association of eosinophil counts with clinical outcomes after SAH.

Methods

This retrospective observational study included patients with SAH admitted from January 2009 to July 2016. Variables included demographics, modified Fisher scale (mFS), Hunt-Hess Scale (HHS), global cerebral edema (GCE), and the presence of any infection. Peripheral eosinophil counts were examined as part of routine clinical care on admission and daily for 10 days after aneurysmal rupture. Outcome measures included dichotomized discharge mortality, modified Ranked Scale (mRS) score, delayed cerebral ischemia (DCI), vasospasm, and need for ventriculoperitoneal shunt (VPS). Statistical tests included the chi-square test, Student's t-test, and multivariable logistic regression (MLR) model.

Results

A total of 451 patients were included. The median age was 54 (IQR 45, 63) years, and 295 (65.4%) were female patients. On admission, 95 patients (21.1%) had a high HHS (>4), and 54 (12.0%) had GCE. A total of 110 (24.4%) patients had angiographic vasospasm, 88 (19.5%) developed DCI, 126 (27.9%) had an infection during hospitalization, and 56 (12.4%) required VPS. Eosinophil counts increased and peaked on days 8-10. Higher eosinophil counts on days 3-5 and day 8 were seen in patients with GCE (p < 0.05). Higher eosinophil counts on days 7-9 (p < 0.05) occurred in patients with poor discharge functional outcomes. In multivariable logistic regression models, higher day 8 eosinophil count was independently associated with worse discharge mRS (OR 6.72 [95% CI 1.27, 40.4], p = 0.03).

Conclusion

This study demonstrated that a delayed increase in eosinophils after SAH occurs and may contribute to functional outcomes. The mechanism of this effect and the relationship with SAH pathophysiology merit further investigation.

Corticosteroid-Dependent Leukocytosis Masks the Predictive Potential of White Blood Cells for Delayed Cerebral Ischemia and Ventriculoperitoneal Shunt Dependency in Aneurysmatic Subarachnoid Hemorrhage

A multitude of pathological and inflammatory processes determine the clinical course after aneurysmal subarachnoid hemorrhage (aSAH). However, our understanding of predictive factors and therapeutic consequences is limited. We evaluated the predictive value of clinically relevant factors readily available in the ICU setting, such as white blood cell (WBC) count and CRP, for two of the leading comorbidities, delayed cerebral ischemia (DCI) and ventriculoperitoneal (VP) shunt dependency in aSAH patients with and without corticosteroid treatment. We conducted a retrospective analysis of 484 aSAH patients admitted to our institution over an eight-year period. Relevant clinical factors affecting the risk of DCI and VP shunt dependency were identified and included in a multivariate logistic regression model. Overall, 233/484 (48.1%) patients were treated with corticosteroids. Intriguingly, predictive factors associated with the occurrence of DCI differed significantly depending on the corticosteroid treatment status (dexamethasone group: Hunt and Hess grade (p = 0.002), endovascular treatment (p = 0.016); no-dexamethasone group: acute hydrocephalus (p = 0.018), peripheral leukocyte count 7 days post SAH (WBC at day 7) (p = 0.009)). Similar disparities were found for VP shunt dependency (dexamethasone group: acute hydrocephalus (p = 0.002); no-dexamethasone group: WBC d7 (p = 0.036), CRP peak within 72 h (p = 0.015)). Our study shows that corticosteroid-induced leukocytosis negates the predictive prognostic potential of systemic inflammatory markers for DCI and VP shunt dependency, which has previously been neglected and should be accounted for in future studies.

Cannabidiol’s Multifactorial Mechanisms Has Therapeutic Potential for Aneurysmal Subarachnoid Hemorrhage: a Review

Subarachnoid hemorrhage (SAH) is a major health burden that accounts for approximately 5% of all strokes. The most common cause of a non-traumatic SAH is the rupture of a cerebral aneurysm. The most common symptom associated with SAH is a headache, often described as “the worst headache of my life.” Delayed cerebral ischemia (DCI) is a major factor associated with patient mortality following SAH and is often associated with SAH-induced cerebral vasospasm (CV). Cannabidiol (CBD) is emerging as a potential drug for many therapeutic purposes, including epilepsy, anxiety, and pain relief. We aim to review the potential use of CBD as a treatment option for post-SAH critically ill patients. Through a literature review, we evaluated the known pharmacology and physiological effects of CBD and correlated those with the pathophysiological outcomes associated with cerebral vasospasm following subarachnoid hemorrhage. Although overlap exists, data were formatted into three major categories: anti-inflammatory, vascular, and neuroprotective effects. Based on the amount of information known about the actions of CBD, we hypothesize the anti-inflammatory effects are likely to be the most promising therapeutic mechanism. However, its cardiovascular effects through calcium regulation and its neuroprotective effects against cell death, excitotoxicity, and oxidative stress are all plausible mechanisms by which post-SAH critically ill patients may benefit from both early and late intervention with CBD. More research is needed to better understand if and how CBD might affect neurological and vascular functions in the brain following injury such as subarachnoid hemorrhage.

Prognostic significance of combined score of fibrinogen and neutrophil-lymphocyte ratio for functional outcome in patients with aneurysmal subarachnoid hemorrhage

Objective

To explore the relationship between fibrinogen and neutrophil to lymphocyte ratio (F-NLR) score and functional outcomes after aneurysmal subarachnoid hemorrhage (aSAH).

Method

A retrospective study was conducted that involved all consecutive patients with aSAH admitted to our institution from March 2018 to October 2021. Factors, such as demographics, comorbidities, clinical characteristics, neuroradiological data, and laboratory parameters, were collected from institutional databases. All patients achieved neurological assessment using the modified Rankin Scale (mRS) score 3 months after discharge to clarify the functional outcomes. The results were classified as favorable (mRS score 0–2) and unfavorable (mRS score 3–6). Univariate and multivariable analyses were performed to identify the relevant factors between inflammatory markers and functional outcomes after aSAH. Subsequently, a receiver operating characteristic (ROC) curve analysis was conducted to evaluate the predicting performance of variables. A propensity score match (PSM) was performed to correct imbalances in patients' baseline characteristics.

Results

Finally, 256 patients with aSAH were included in the study cohort. A total of 94 (36.7%) patients had an unfavorable outcome. F-NLR scores were 0 [interquartile range (IQR) 0–1] and 1 (IQR 1–2) in patients with favorable and unfavorable outcomes, respectively (p < 0.001). After adjustment, the F-NLR score on admission remained significantly associated with unfavorable outcomes in patients with aSAH. In the multivariable analysis, the F-NLR score was regarded as an independent risk factor of unfavorable outcomes [odds ratio (OR) 3.113, 95% CI 1.755–5.523, p < 0.001]. In ROC analysis, the optimal cutoff value of the F-NLR score was 0.5 points. Two cohorts (n = 86 in each group) obtained from PSM with low F-NLR scores (0 points) and high F-NLR scores (1–2 points) were used for analysis. A significantly higher unfavorable functional outcome rate was observed in patients with high F-NLR scores (33.7 vs. 9.3%, p < 0.001). The area under the curve (AUC) values of F-NLR scores before and after PSM were 0.767 and 0.712, respectively.

Conclusion

Fibrinogen and neutrophil to lymphocyte ratio score was an independent risk parameter associated with unfavorable functional outcomes at 3 months after aSAH. A higher F-NLR score predicts the occurrence of poor functional outcomes.

Systemic inflammatory markers of persistent cerebral edema after aneurysmal subarachnoid hemorrhage

Background

Cerebral edema (CE) at admission is a surrogate marker of ‘early brain injury’ (EBI) after subarachnoid hemorrhage (SAH). Only recently has the focus on the changes in CE after SAH such as delayed resolution or newly developed CE been examined. Among several factors, an early systemic inflammatory response has been shown to be associated with CE. We investigate inflammatory markers in subjects with early CE which does not resolve, i.e., persistent CE after SAH.

Methods

Computed tomography scans of SAH patients were graded at admission and at 7 days after SAH for CE using the 0–4 ‘subarachnoid hemorrhage early brain edema score’ (SEBES). SEBES ≤ 2 and SEBES ≥ 3 were considered good and poor grade, respectively. Serum samples from the same subject cohort were collected at 4 time periods (at < 24 h [T1], at 24 to 48 h [T2]. 3–5 days [T3] and 6–8 days [T4] post-admission) and concentration levels of 17 cytokines (implicated in peripheral inflammatory processes) were measured by multiplex immunoassay. Multivariable logistic regression analyses were step-wisely performed to identify cytokines independently associated with persistent CE adjusting for covariables including age, sex and past medical history (model 1), and additional inclusion of clinical and radiographic severity of SAH and treatment modality (model 2).

Results

Of the 135 patients enrolled in the study, 21 of 135 subjects (15.6%) showed a persistently poor SEBES grade. In multivariate model 1, higher Eotaxin (at T1 and T4), sCD40L (at T4), IL-6 (at T1 and T3) and TNF-α (at T4) were independently associated with persistent CE. In multivariate model 2, Eotaxin (at T4: odds ratio [OR] = 1.019, 95% confidence interval [CI] = 1.002–1.035) and possibly PDGF-AA (at T4), sCD40L (at T4), and TNF-α (at T4) was associated with persistent CE.

Conclusions

We identified serum cytokines at different time points that were independently associated with persistent CE. Specifically, persistent elevations of Eotaxin is associated with persistent CE after SAH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02564-1.

High Expression of PDK4 Could Play a Potentially Protective Role by Attenuating Oxidative Stress after Subarachnoid Hemorrhage

Pyruvate dehydrogenase (PDH), a key enzyme on the mitochondrial outer membrane, has been found to decrease activity notably in early brain injury (EBI) after subarachnoid hemorrhage (SAH). It has been demonstrated that PDH is associated with the production of reactive oxygen species (ROS) and apoptosis. Hence, in this study, we aimed to determine the cause of the decreased PDH activity and explore the potential role of PDH in EBI. We investigated the expression changes of PDH and pyruvate dehydrogenase kinase (PDK) in vivo and in vitro. Then, we explored the possible effects of PDH and ROS after SAH. The results showed that early overexpression of PDK4 promoted the phosphorylation of PDH, inhibited PDH activity, and may play a protective role after SAH in vivo and in vitro. Finally, we investigated the levels of PDK4 and pyruvate, which accumulated due to decreased PDH activity, in the cerebrospinal fluid (CSF) of 34 patients with SAH. Statistical analysis revealed that PDK4 and pyruvate expression was elevated in the CSF of SAH patients compared with that of controls, and this high expression correlated with the degree of neurological impairment and long-term outcome. Taken together, the results show that PDK4 has the potential to serve as a new therapeutic target and biomarker for assisting in the diagnosis of SAH severity and prediction of recovery.

Inflammation and the role of infection: Complications and treatment options following neurotrauma

Traumatic brain injury can have devastating consequences for patients and extended hospital stays and recovery course. Recent data indicate that the initial insult causes profound changes to the immune system and leads to a pro-inflammatory state. This alteration in homeostasis predisposes patients to an increased risk of infection and underlying autoimmune conditions. Increased emphasis has been placed on understanding this process both in the clinical and preclinical literature. This review highlights the intrinsic inflammatory conditions that can occur within the initial hospital stay, discusses long-term immune consequences, highlights emerging treatment options, and delves into important pathways currently being investigated with preclinical models.

2-Methoxyestradiol Alleviates Neuroinflammation and Brain Edema in Early Brain Injury After Subarachnoid Hemorrhage in Rats

Objective

Numerous studies have shown that neuroinflammation and brain edema play an important role in early brain injury (EBI) after subarachnoid hemorrhage (SAH). 2-Methoxyestradiol (2-ME) has been shown to have anti-inflammatory and anti-angiogenic effects. This study aimed to investigate the effects of 2-ME on neuroinflammation and brain edema after SAH and its underlying mechanism of action.

Methods

Rats were used to produce an endovascular puncture model of SAH. 2-ME or the control agent was injected intraperitoneally 1 h after SAH induction. At 24 h after surgery, the neurological score, SAH grading, brain water content, and blood–brain barrier (BBB) permeability were examined. The microglial activation level in the rat brain tissue was determined using immunofluorescence staining, whereas the cell apoptosis in the rat brain tissue was assessed using terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, the levels of Interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were measured by enzyme linked immunosorbent assay, and the expression levels of ZO-1, occludin, hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and matrix metallopeptidase (MMP)-9 in the rat brain tissue were determined using western blotting.

Results

Twenty-four hours after SAH, brain water content, BBB permeability, microglial activation, and cell apoptosis were significantly increased, whereas neurological function deteriorated significantly in rats. Treatment with 2-ME significantly decreased brain water content, BBB permeability, microglial cell activation, and cell apoptosis and improved neurological dysfunction in rats. Treatment with 2-ME reduced the expression levels of inflammatory factors (IL-1β, IL-6, and TNF-α), which were significantly elevated 24 h after SAH. Treatment with 2-ME alleviated the disruption of tight junction proteins (ZO-1 and occludin), which significantly decreased 24 h after SAH. To further determine the mechanism of this protective effect, we found that 2-ME inhibited the expression of HIF-1α, MMP-9, and VEGF, which was associated with the inflammatory response to EBI and BBB disruption after SAH.

Conclusion

2-ME alleviated neuroinflammation and brain edema as well as improved neurological deficits after SAH in rats. The neuroprotective effect of 2-ME on EBI after SAH in rats may be related to the inhibition of neuroinflammation and brain edema.

Role of Dexmedetomidine in Aneurysmal Subarachnoid Hemorrhage: A Comprehensive Scoping Review

Dexmedetomidine (DEX), an α2-adrenergic agonist, has been widely used for anesthesia, pain control, and intensive care unit sedation. Besides sleep-like sedation, DEX has many other beneficial effects, such as anti-inflammation, antioxidation, and anticell death. Subarachnoid hemorrhage (SAH), a severe and potentially fatal form of stroke, is a complex disease that is divided into 2 phases: early brain injury and delayed cerebral ischemia. In each phase, several pathologic changes are involved, including disturbed intracranial homeostasis, metabolic failure, blood-brain barrier damage, vasospasm, microthrombosis, and cortical spreading depolarization. DEX has been shown to have an effect on these SAH-related pathologic processes. Research shows that DEX could serve as a protective therapy for patients with SAH due to its ability to maintain stable intracerebral homeostasis, balance coagulation-fibrinolysis, repair a damaged blood-brain barrier as well as prevent vasospasm and suppress cortical spreading depolarization by anti-inflammatory, antioxidative, antiapoptotic, and vasoconstriction-dilation effects. In this scoping review, we critically assess the existing data on the potential protective effect of DEX after SAH. So far, only 1 retrospective clinical trial assessing the effect of DEX on clinical outcomes after SAH has been performed. Hence, more trials are still needed as well as translational research bringing results from bench to bedside.

Assessment of Sustained Systemic Inflammatory Response Syndrome and CSF Markers as Predictive Values Associated with Shunt-Dependent Hydrocephalus after Aneurysmal Subarachnoid Hemorrhage

Aim of the study: This study was conducted to detect incidence and risk factors of shunt-dependent hydrocephalus, including Systemic Inflammatory Response Syndrome. Patients and methods: After obtaining ethical approval from the research ethics committee of Cairo University, this study was conducted in two phases, phase I in the form of follow up study to detect the incidence of shunt dependent hydrocephalus in patients with ruptured subarachnoid aneurysm then phase II in the form of comparative one to detect the risk factors of acquisition of shunt dependent hydrocephalus and detect the predictive role of SIRS in SDH. The study included 90 patients with ruptured subarachnoid aneurysms followed up in the department of neurosurgery of Cairo university hospital from April 2018 to April 2020. Results: The incidence of shunt-dependent hydrocephalus was 28% among the studied patients with significant association with high-grade SIRS, Fisher score, Hunt and Hess score, and leukocytosis. The CSF white blood cells and protein were significantly higher in the hydrocephalus group. Also, there was significant hypernatremia among the hydrocephalic group. Conclusion: Despite the study's analytical design, we observed a link between high fisher, SIRS, hypernatremia, and shunt-dependent hydrocephalus in aneurysmal SAH patients. Serum sodium, CSF WBCs, and protein may all be used to predict HC.

Heparin in the treatment of aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

OBJECTIVE

Cerebral vasospasm and the resulting infarction remain the most devastating complications of aneurysmal subarachnoid hemorrhage (aSAH). Limited treatment options are available, with nimodipine as the only approved prophylactic medication. In addition to its anticoagulant properties, heparin also has a pleiotropic and anti-inflammatory effect that could be beneficial in vasospasm. In this study, the authors sought to evaluate the efficacy and safety of heparin in the treatment of aSAH.

METHODS

The PubMed, EBSCOhost, Europe PMC, and Cochrane Central databases were searched to find studies including patients with aSAH who were treated with intravenous unfractionated heparin (UFH) after an aneurysm-securing procedure. Studies that did not include a comparison with UFH or low-molecular-weight heparin in deep vein thrombosis prophylactic doses were excluded. The primary outcome was cerebral vasospasm, and the secondary outcomes were cerebral infarction, clinical deterioration caused by delayed cerebral ischemia, bleeding complications, and thromboembolism complications.

RESULTS

Overall, 5 nonrandomized studies were included; 4 studies evaluated the safety and 3 studies evaluated the efficacy of intravenous heparin. From the analysis of 3 studies with a total of 895 patients, administration of intravenous UFH for > 48 hours was related to a significantly lower rate of cerebral infarction (OR 0.44, 95% CI 0.25–0.79). No significant association was found with other efficacy outcomes. Regarding cognitive outcome, one study found a significant improvement in Montreal Cognitive Assessment scores; however, the functional outcome as indicated by the modified Rankin Scale score was not improved by heparin administration. From the analysis of 4 studies with 1099 patients, no significant increases in bleeding and other complications were found.

CONCLUSIONS

Administration of intravenous UFH for more than 48 hours reduced the rate of cerebral infarction with a good safety profile. This result supports the ongoing clinical trial.

Leukocytosis and C-Reactive Protein May Predict Development of Secondary Cerebral Vasospasm in Patients with Aneurysmal Subarachnoid Hemorrhage

Background and Objectives: Secondary cerebral vasospasm (CV) with subsequent delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) remains an unpredictable pathology. The aim of this retrospective study was to investigate the association between inflammatory parameters, white blood cell (WBC) count, and C-reactive protein plasma levels (CRP) and the occurrence of secondary CV in patients with aSAH. Materials and Methods: The medical records of 201 Intensive Care Unit patients in Riga East University Hospital with aSAH were retrospectively reviewed in a 24-month period. WBC count and CRP values were observed at admission to the hospital and on the third day. According to the inclusion criteria, 117 (48 males) participants were enrolled for further analysis, with average age of 56 ± 15 years (mean ± SD). In total, secondary CV was diagnosed in 21.4% of cases, and DCI in 22.4% of cases. The patients were classified into three groups: SAH-CV group (n = 25), SAH-DCI group (n = 12), and SAH or control group (n = 80), for comparative analysis. Results: We found that SAH-CV patients demonstrated notably higher inflammatory parameters compared to controls: WBC 13.2 ± 3.3 × 10⁹/L vs. 11.2 ± 3.7 × 10⁹/L; p = 0.01 and CRP median 9.3 mg/L vs. 1.9 mg/L; p < 0.001, respectively. We found that the odds of developing CV increased by 5% for each CRP increase of 1 mg/L at admission (OR, 1.05; CI, 1.014–1.087; p = 0.006). Concomitantly, the odds increased by 16% for every rise in WBC count of 1 × 10⁹/L (OR, 1.16; CI, 1.02–1.32; p = 0.02). WBC count was associated with the occurrence of CV with 96% sensitivity and 40% specificity, with a cut off level of 10.015 × 10⁹/L and AUC 0.683; p = 0.006. CRP displayed 54% sensitivity and 90% specificity with a cut off value of 8.9 mg/L and AUC 0.751; p < 0.001. Moreover, higher values of inflammatory parameters at admission correlated with a longer stay in ICU (r = 0.3, p = 0.002 for WBC count and r = 0.305, p = 0.002 for CRP values), and poor outcome (death) was significantly associated with higher CRP values at admission and on the third day (16.1. vs. 2.2. and 57.4. vs. 11.1, p < 0.001, respectively). Higher mortality was detected in SAH-CV patients (32%) compared to controls (6.3%; p < 0.001). Conclusions: Inflammatory parameters such as WBC count and CRP values at admission might be helpful to predict the development of secondary CV.

Using a Transection Paradigm to Enhance the Repair Mechanisms of an Investigational Human Cell Therapy

One promising strategy in cell therapies for Parkinson’s disease (PD) is to harness a patient’s own cells to provide neuroprotection in areas of the brain affected by neurodegeneration. No treatment exists to replace cells in the brain. Thus, our goal has been to support sick neurons and slow neurodegeneration by transplanting living repair tissue from the peripheral nervous system into the substantia nigra of those with PD. Our group has pioneered the transplantation of transection-activated sural nerve fascicles into the brain of human subjects with PD. Our experience in sural nerve transplantation has supported the safety and feasibility of this approach. As part of a paradigm to assess the reparative properties of human sural nerve following a transection injury, we collected nerve tissue approximately 2 weeks after sural nerve transection for immunoassays from 15 participants, and collected samples from two additional participants for single nuclei RNA sequencing. We quantified the expression of key neuroprotective and select anti-apoptotic genes along with their corresponding protein levels using immunoassays. The single nuclei data clustered into 10 distinctive groups defined on the basis of previously published cell type-specific genes. Transection-induced reparative peripheral nerve tissue showed RNA expression of neuroprotective factors and anti-apoptotic factors across multiple cell types after nerve injury induction. Key proteins of interest (BDNF, GDNF, beta-NGF, PDGFB, and VEGF) were upregulated in reparative tissue. These results provide insight on this repair tissue’s utility as a neuroprotective cell therapy.

Exploration of treatments for subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) continues to be a leading cause of morbidity and mortality, with cerebral vasospasm as a common etiology of worse clinical progression. The purpose of this study was to evaluate and review the current literature concerning the effective treatment of SAH. The treatment options for SAH are expanding as new therapeutic targets are identified. Nimodipine is the primary medication prescribed due to its neuroprotective properties. In addition, certain drugs can enhance lymphatic flow and influence the recovery process, such as Dexmedetomidine, SSRIs, and DL-3-n-butylphthalide. Vasospastic and ischemic patients commonly undergo transluminal balloon angioplasty. Clinical trials have not yet provided conclusive evidence to support the use of magnesium or statins. Moreover, other agents such as calcium channel blockers, milrinone, hydrogen sulfide, exosomes, erythropoietin, cilostazol, fasudil, albumin, Eicosapentaenoic acid, corticosteroids, minocycline, and stellate ganglion blockade should be investigated further.

Increased Systemic Immune-Inflammation Index Is Associated With Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage Patients

Background: Systemic immune-inflammation index (SII) is a novel biomarker that reflects the state of a patient's inflammatory and immune status. This study aimed to determine the clinical significance of SII as a predictor of delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (SAH).

Methods: Retrospective data were collected from aneurysmal SAH patients who had been admitted to our hospital between January 2015 and October 2019. Both univariate and multivariate analyses were performed to investigate whether SII was an independent predictor of DCI. In addition, the receiver operating characteristic (ROC) curve and area under the curve (AUC) were also evaluated.

Results: There were 333 patients with aneurysmal SAH included in this study. Multivariate logistic analysis revealed that a modified Fisher grade 3 and 4 score [odds ratio (OR) = 7.851, 95% confidence interval (CI): 2.312–26.661, P = 0.001] and elevated SII (OR = 1.001, 95% CI: 1.001–1.002, P < 0.001) were independent risk factors for DCI. ROC curves showed that SII could predict DCI with an AUC of 0.860 (95% CI: 0.818–0.896, P < 0.001). The optimal cut-off value for SII to predict DCI was 1,424, and an SII ≥ 1,424 could predict DCI with a sensitivity of 93.1% and a specificity of 68.1%. Patients with higher SII value on admission tended to have higher incidence of acute hydrocephalus and DCI, greater modified Fisher and Hunt-Hess scales, and poorer outcomes.

Conclusions: SII is an independent predictor of DCI in patients with aneurysmal SAH. The SII system can be implemented in a routine clinical setting to help clinicians diagnose patients with high risk of DCI.

Hydrogen gas post-conditioning alleviates cognitive dysfunction and anxiety-like behavior in a rat model of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) results in high rates of mortality and lasting disability. Hydrogen gas (H2) is an antioxidant with demonstrated neuroprotective efficacy. The present study examined the therapeutic efficacy of H2 inhalation on early brain injury following experimental SAH in rats and the potential underlying molecular mechanisms. The rats were randomly separated into three groups (n=36 per group): Sham, SAH and SAH + H2. Endovascular perforation of the right internal carotid artery was used to establish SAH. After perforation, rats in the SAH + H2 group inhaled 2.9% H2 with regular oxygen for 2 h. Then, 24 h post-SAH, TUNEL staining was used to detect apoptotic neurons, and both immunostaining and western blotting were conducted to examine changes in p38 MAPK activity and the expression levels of apoptotic regulators (Bcl-2, Bax and cleaved caspase-3) in the ventromedial prefrontal cortex. Then, 30 day post-SAH, Nissl staining was performed to detect neuronal injury, brain MRI was conducted to detect gross changes in brain structure and metabolism, the open field test was used to assess anxiety and the novel object recognition test was performed to assess memory. H2 inhalation following experimental SAH stabilized brain metabolites, improved recognition memory and reduced anxiety-like behavior, the neuronal apoptosis rate, phosphorylated p38 MAPK expression, cleaved caspase-3 expression and the Bax/Bcl-2 ratio. Collectively, the present results suggested that H2 inhalation can alleviate SAH-induced cognitive impairment, behavioral abnormalities and neuronal apoptosis in rats, possibly via inhibition of the p38 MAPK signal pathway.

MicroRNAs as Biomarkers for Predicting Complications following Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a high mortality hemorrhagic stroke that affects nearly 30,000 patients annually in the United States. Approximately 30% of aSAH patients die during initial hospitalization and those who survive often carry poor prognosis with one in five having permanent physical and/or cognitive disabilities. The poor outcome of aSAH can be the result of the initial catastrophic event or due to the many acute or delayed neurological complications, such as cerebral ischemia, hydrocephalus, and re-bleeding. Unfortunately, no effective biomarker exists to predict or diagnose these complications at a clinically relevant time point when neurologic injury can be effectively treated and managed. Recently, a number of studies have demonstrated that microRNAs (miRNAs) in extracellular biofluids are highly associated with aSAH and complications. Here we provide an overview of the current research on relevant human studies examining the correlation between miRNAs and aSAH complications and discuss the potential application of using miRNAs as biomarkers in aSAH management.

Intracerebral Iron Accumulation may be Associated with Secondary Brain Injury in Patients with Poor Grade Subarachnoid Hemorrhage

BACKGROUND

The amount of intracranial blood is a strong predictor of poor outcome after subarachnoid hemorrhage (SAH). Here, we aimed to measure iron concentrations in the cerebral white matter, using the cerebral microdialysis (CMD) technique, and to associate iron levels with the local metabolic profile, complications, and functional outcome.

METHODS

For the observational cohort study, 36 patients with consecutive poor grade SAH (Hunt & Hess grade of 4 or 5, Glasgow Coma Scale Score ≤ 8) undergoing multimodal neuromonitoring were analyzed for brain metabolic changes, including CMD iron levels quantified by graphite furnace atomic absorption spectrometry. The study time encompassed 14 days after admission. Statistical analysis was performed using generalized estimating equations.

RESULTS

Patients were admitted in a poor clinical grade (n = 26, 72%) or deteriorated within 24 h (n = 10, 28%). The median blood volume in the subarachnoid space was high (SAH sum score = 26, interquartile range 20-28). Initial CMD iron was 44 µg/L (25-65 µg/L), which significantly decreased to a level of 25 µg/L (14-30 µg/L) at day 4 and then constantly increased over the remaining neuromonitoring days (p < 0.01). A higher intraventricular hemorrhage sum score (≥ 5) was associated with higher CMD iron levels (Wald-statistic = 4.1, df  = 1, p = 0.04) but not with the hemorrhage load in the subarachnoid space (p = 0.8). In patients developing vasospasm, the CMD iron load was higher, compared with patients without vasospasm (Wald-statistic = 4.1, degree of freedom = 1, p = 0.04), which was not true for delayed cerebral infarction (p = 0.4). Higher iron concentrations in the brain extracellular fluid (34 µg/L, 36-56 µg/L vs. 23 µg/L, 15-37 µg/L) were associated with mitochondrial dysfunction (CMD lactate to pyruvate ratio > 30 and CMD-pyruvate > 70 µM/L, p < 0.001). Brain extracellular iron load was not associated with functional outcome after 3 months (p > 0.5).

CONCLUSIONS

This study suggests that iron accumulates in the cerebral white matter in patients with poor grade SAH. These findings may support trials aiming to scavenger brain extracellular iron based on the hypothesis that iron-mediated neurotoxicity may contribute to acute and secondary brain injury following SAH.

The emerging roles of absent in melanoma 2 (AIM2) inflammasome in central nervous system disorders

As a double-stranded DNA (dsDNA) sensor, the PYHIN family member absent in melanoma 2 (AIM2) is an essential component of the inflammasome families. Activation of AIM2 by dsDNA leads to the assembly of cytosolic multimolecular complexes termed the AIM2 inflammasome, resulting in activation of caspase-1, the maturation and secretion of pro-inflammatory cytokines interleukin (IL)-1β and IL-18, and pyroptosis. Multiple central nervous system (CNS) diseases are accompanied by immune responses and inflammatory cascade. As the resident macrophage cells, microglia cells act as the first and main form of active immune defense in the CNS. AIM2 is highly expressed in microglia as well as astrocytes and neurons and is essential in neurodevelopment. In this review, we highlight the recent progress on the role of AIM2 inflammasome in CNS disorders, including cerebral stroke, brain injury, neuropsychiatric disease, neurodegenerative diseases, and glioblastoma.

Differential polarization and activation dynamics of systemic T helper cell subsets after aneurysmal subarachnoid hemorrhage (SAH) and during post-SAH complications

Aneurysmal subarachnoid hemorrhage (SAH) is associated with high morbidity and mortality. Devastating post-SAH complications, such as cerebral vasospasm (CVS), delayed cerebral ischemia or seizures to mention a few, are mainly responsible for the poor clinical outcome. Inflammation plays an indispensable role during early brain injury (EBI) and delayed brain injury (DBI) phases over which these complications arise. T helper cells are the major cytokine secreting cells of adaptive immunity that can polarize to multiple functionally unique sub-populations. Here, we investigate different CD4+ T cell subsets during EBI and DBI phases after SAH, and their dynamics during post-SAH complications. Peripheral venous blood from 15 SAH patients during EBI and DBI phases, was analyzed by multicolour flowcytometry. Different subsets of CD3+ CD4+ T cells were characterized by differential cell surface expression of CXCR3 and CCR6 into Th1, Th2, Th17, whereas Tregs were defined by CD25^hiCD127^lo. The analysis of activation states was done by the expression of stable activation markers CD38 and HLA-DR. Interestingly, compared to healthy controls, Tregs were significantly increased during both EBI and DBI phases. Different activation states of Tregs showed differential significant increase during EBI and DBI phases compared to controls. HLA-DR− CD38+ Tregs were significantly increased during DBI phase compared to EBI phase in SAH patients developing CVS, seizures and infections. However, HLA-DR− CD38− Tregs were significantly reduced during EBI phase in patients with cerebral ischemia (CI) compared to those without CI. HLA-DR− CD38− Th2 cells were significantly increased during EBI phase compared to controls. A significant reduction in Th17/Tregs and HLA-DR− CD38+ Th17/Tregs ratios was observed during both EBI and DBI phases compared to controls. While HLA-DR− CD38− Th17/Tregs and HLA-DR− CD38− Th1/Th2 ratios were impaired only during EBI phase compared to controls. In conclusion, CD4+ T cell subsets display dynamic and unique activation patterns after SAH and during the course of the manifestation of post-SAH complications, which may be helpful for the development of precision neurovascular care. However, to claim this, confirmatory studies with larger patient cohorts, ideally from different ethnic backgrounds, are required. Moreover, our descriptive study may be the grounds for subsequent lab endeavors to explore the underlying mechanisms of our observations.

Cerebrovascular Anomalies: Perspectives From Immunology and Cerebrospinal Fluid Flow

Appropriate vascular function is essential for the maintenance of central nervous system homeostasis and is achieved through virtue of the blood-brain barrier; a specialized structure consisting of endothelial, mural, and astrocytic interactions. While appropriate blood-brain barrier function is typically achieved, the central nervous system vasculature is not infallible and cerebrovascular anomalies, a collective terminology for diverse vascular lesions, are present in meningeal and cerebral vasculature supplying and draining the brain. These conditions, including aneurysmal formation and rupture, arteriovenous malformations, dural arteriovenous fistulas, and cerebral cavernous malformations, and their associated neurological sequelae, are typically managed with neurosurgical or pharmacological approaches. However, increasing evidence implicates interacting roles for inflammatory responses and disrupted central nervous system fluid flow with respect to vascular perturbations. Here, we discuss cerebrovascular anomalies from an immunologic angle and fluid flow perspective. We describe immune contributions, both common and distinct, to the formation and progression of diverse cerebrovascular anomalies. Next, we summarize how cerebrovascular anomalies precipitate diverse neurological sequelae, including seizures, hydrocephalus, and cognitive effects and possible contributions through the recently identified lymphatic and glymphatic systems. Finally, we speculate on and provide testable hypotheses for novel nonsurgical therapeutic approaches for alleviating neurological impairments arising from cerebrovascular anomalies, with a particular emphasis on the normalization of fluid flow and alleviation of inflammation through manipulations of the lymphatic and glymphatic central nervous system clearance pathways.

Pregabalin Protects Brain Tissue from Subarachnoid Hemorrhage by Enhancing HIF-1α/eNOS Signaling and VEGF Production

OBJECTIVE

We investigated the effects of different doses of pregabalin on the pathophysiologic changes in early brain injury after subarachnoid hemorrhage (SAH) in rats.

METHODS

Thirty-eight Wistar albino rats were divided into 4 groups: control (n = 8), SAH (n = 10), SAH plus 30 mg/kg/day of pregabalin (n = 10), and SAH plus 60 mg/kg/day of pregabalin (n = 10). SAH was induced with 0.3 mL of autologous blood injected to the cisterna magna of rats. Pregabalin was administered intraperitoneally. Oxidative stress markers, mRNA expression of endothelial nitric oxide synthase, hypoxia-inducible factor-1α, and vascular endothelial growth factor, and histopathological changes were evaluated.

RESULTS

Pregabalin increased mRNA expression of endothelial nitric oxide synthase, hypoxia-inducible factor-1α, and vascular endothelial growth factor in a dose-dependent manner. Significant improvement in the histopathological parameters was observed at 60 mg/kg, including a decrease in diffuse hemorrhagic areas, edema and apoptotic bodies in the associated cortical area, evident vacuolization in the hippocampal area, and apoptotic bodies. However, these improvements were not observed with the lower dose (30 mg/kg). In contrast, the antioxidant effect was greater with 30 mg/kg of pregabalin than with 60 mg/kg.

CONCLUSIONS

Although the antioxidant effect was significant with the lower dose of pregabalin, the anti-inflammatory effects via vasodilatation were more marked with the higher dose. Significant improvements in the histopathological changes were observed with the higher dose of pregabalin. The dose-dependent effects of pregabalin on SAH should be evaluated in animal studies as a function of time and in the acute and chronic phases.

Toll-Like Receptor Signaling Pathways: Novel Therapeutic Targets for Cerebrovascular Disorders

Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.

The Role of NLRP3 Inflammasome in Cerebrovascular Diseases Pathology and Possible Therapeutic Targets

Cerebrovascular diseases are pathological conditions involving impaired blood flow in the brain, primarily including ischaemic stroke, intracranial haemorrhage, and subarachnoid haemorrhage. The nucleotide-binding and oligomerisation (NOD) domain-like receptor (NLR) family pyrin domain (PYD)-containing 3 (NLRP3) inflammasome is a protein complex and a vital component of the immune system. Emerging evidence has indicated that the NLRP3 inflammasome plays an important role in cerebrovascular diseases. The function of the NLRP3 inflammasome in the pathogenesis of cerebrovascular diseases remains an interesting field of research. In this review, we first summarised the pathological mechanism of cerebrovascular diseases and the pathological mechanism of the NLRP3 inflammasome in aggravating atherosclerosis and cerebrovascular diseases. Second, we outlined signalling pathways through which the NLRP3 inflammasome participates in aggravating or mitigating cerebrovascular diseases. Reactive oxygen species (ROS)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), ROS/thioredoxin-interacting protein (TXNIP) and purinergic receptor-7 (P2X7R) signalling pathways can activate the NLRP3 inflammasome; activation of the NLRP3 inflammasome can aggravate cerebrovascular diseases by mediating apoptosis and pyroptosis. Autophagy/mitochondrial autophagy, nuclear factor E2-related factor-2 (Nrf2), interferon (IFN)-β, sirtuin (SIRT), and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) reportedly alleviate cerebrovascular diseases by inhibiting NLRP3 inflammasome activation. Finally, we explored specific inhibitors of the NLRP3 inflammasome based on the two-step activation of the NLRP3 inflammasome, which can be developed as new drugs to treat cerebrovascular diseases.

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/).

A Highly Predictive MicroRNA Panel for Determining Delayed Cerebral Vasospasm Risk Following Aneurysmal Subarachnoid Hemorrhage

Approximately one-third of aneurysmal subarachnoid hemorrhage (aSAH) patients develop delayed cerebral vasospasm (DCV) 3-10 days after aneurysm rupture resulting in additional, permanent neurologic disability. Currently, no validated biomarker is available to determine the risk of DCV in aSAH patients. MicroRNAs (miRNAs) have been implicated in virtually all human diseases, including aSAH, and are found in extracellular biofluids including plasma and cerebrospinal fluid (CSF). We used a custom designed TaqMan Low Density Array miRNA panel to examine the levels of 47 selected brain and vasculature injury related miRNAs in CSF and plasma specimens collected from 31 patients with or without DCV at 3 and 7 days after aSAH, as well as from eight healthy controls. The analysis of the first 18-patient cohort revealed a striking differential expression pattern of the selected miRNAs in CSF and plasma of aSAH patients with DCV from those without DCV. Importantly, this differential expression was observed at the early time point (3 days after aSAH), before DCV event occurs. Seven miRNAs were identified as reliable DCV risk predictors along with a prediction model constructed based on an array of additional 19 miRNAs on the panel. These chosen miRNAs were then used to predict the risk of DCV in a separate, testing cohort of 15 patients. The accuracy of DCV risk prediction in the testing cohort reached 87%. The study demonstrates that our novel designed miRNA panel is an effective predictor of DCV risk and has strong applications in clinical management of aSAH patients.

Development of the Cerebrospinal Fluid in Early Stage after Hemorrhage in the Central Nervous System

Extravasation of blood in the central nervous system (CNS) represents a very strong damaged associated molecular patterns (DAMP) which is followed by rapid inflammation and can participate in worse outcome of patients. We analyzed cerebrospinal fluid (CSF) from 139 patients after the CNS hemorrhage. We compared 109 survivors (Glasgow Outcome Score (GOS) 5-3) and 30 patients with poor outcomes (GOS 2-1). Statistical evaluations were performed using the Wilcoxon signed-rank test and the Mann–Whitney U test. Almost the same numbers of erythrocytes in both subgroups appeared in days 0–3 (p = 0.927) and a significant increase in patients with GOS 2-1 in days 7–10 after the hemorrhage (p = 0.004) revealed persistence of extravascular blood in the CNS as an adverse factor. We assess 43.3% of patients with GOS 2-1 and only 27.5% of patients with GOS 5-3 with low values of the coefficient of energy balance (KEB < 15.0) in days 0–3 after the hemorrhage as a trend to immediate intensive inflammation in the CNS of patients with poor outcomes. We consider significantly higher concentration of total protein of patients with GOS 2-1 in days 0–3 after hemorrhage (p = 0.008) as the evidence of immediate simultaneously manifested intensive inflammation, swelling of the brain and elevation of intracranial pressure.

How to diagnose delayed cerebral ischaemia and symptomatic vasospasm and prevent cerebral infarction in patients with subarachnoid haemorrhage

PURPOSE OF REVIEW

Delayed cerebral ischaemia (DCI) complicates the clinical course of patients with subarachnoid haemorrhage (SAH) in 20--30% and substantially worsens outcome. In this review, we describe a multimodal diagnostic approach based on underlying mechanisms of DCI and provide treatment options with a special focus on the most recently published literature.

RECENT FINDINGS

Symptomatic vasospasm refers to clinical deterioration in the presence of vasospasm whereas DCI constitutes multiple causes. Pathophysiologic mechanisms underlying DCI range beyond large vessel vasospasm from neuroinflammation, to microthromboembolism, impaired cerebral autoregulation, cortical spreading depolarizations and many others. The current definition of DCI can be challenged by these mechanisms. We propose a pragmatic approach using a combination of clinical examination, cerebral ultrasonography, neuroimaging modalities and multimodal neuromonitoring to trigger therapeutic interventions in the presence of DCI. In addition to prophylactic nimodipine and management principles to improve oxygen delivery and decrease the brain metabolic demand, other specific interventions include permissive hypertension, intra-arterial application of calcium channel blockers and in selected patients angioplasty.

SUMMARY

The complex pathophysiology underlying DCI urges for a multimodal diagnostic approach triggering targeted interventions. Novel treatment concepts still have to be proven in large trials.

Low-Dose IL-2 Treatment Affords Protection against Subarachnoid Hemorrhage Injury by Expanding Peripheral Regulatory T Cells

Subarachnoid hemorrhage (SAH) is considered a devastating disease, leaving survivors with lifelong neurological impairment. With increased knowledge that regulatory T cells (Tregs) provide protection against stroke, novel agents which could expand Treg populations have been assessed in terms of the potential clinical neuroprotection effect. Using a rat SAH model, we investigated the number variation of Tregs induced by SAH and the protective effect of low-dose interleukin-2 (IL-2) treatment on the SAH model. We observed that the number of peripheral Tregs significantly decreased soon after SAH, accompanying with reactivity recovery after 3 days. Our results also revealed that low-dose IL-2 treatment not only elevated Tregs numbers but significantly reduced neuronal injury and improved neurological functions up to 21 days (d) after SAH. Furthermore, compared with PBS-treatment group, cerebral proinflammatory factors and peripheral neutrophils were significantly suppressed by low-dose IL-2 after SAH. Therefore, the results suggest that low-dose IL-2 treatment is a novel and clinically feasible immunotherapy to improve long-term outcomes after SAH, perhaps via up-regulating Treg population to suppress neuroinflammation induced by SAH.

The Role of Tenascin-C in Tissue Injury and Repair After Stroke

Stroke is still one of the most common causes for mortality and morbidity worldwide. Following acute stroke onset, biochemical and cellular changes induce further brain injury such as neuroinflammation, cell death, and blood-brain barrier disruption. Matricellular proteins are non-structural proteins induced by many stimuli and tissue damage including stroke induction, while its levels are generally low in a normal physiological condition in adult tissues. Currently, a matricellular protein tenascin-C (TNC) is considered to be an important inducer to promote neuroinflammatory cascades and the resultant pathology in stroke. TNC is upregulated in cerebral arteries and brain tissues including astrocytes, neurons, and brain capillary endothelial cells following subarachnoid hemorrhage (SAH). TNC may be involved in blood-brain barrier disruption, neuronal apoptosis, and cerebral vasospasm via the activation of mitogen-activated protein kinases and nuclear factor-kappa B following SAH. In addition, post-SAH TNC levels in cerebrospinal fluid predicted the development of delayed cerebral ischemia and angiographic vasospasm in clinical settings. On the other hand, TNC is reported to promote fibrosis and exert repair effects for an experimental aneurysm via macrophages-induced migration and proliferation of smooth muscle cells. The authors review TNC-induced inflammatory signal cascades and the relationships with other matricellular proteins in stroke-related pathology.

Resolvin D1 Attenuates Innate Immune Reactions in Experimental Subarachnoid Hemorrhage Rat Model

Excessive inflammation is a major cause contributing to early brain injury (EBI) and is associated with negative or catastrophic outcomes of subarachnoid hemorrhage (SAH). Resolvin D1 (RvD1) exerts strong anti-inflammatory and pro-resolving effects on either acute or chronic inflammation of various origin. Henceforth, we hypothesized that RvD1 potentially attenuates excessive inflammation in EBI following SAH. Therefore, we generated a filament perforation SAH model and administered 3 different doses (0.3, 0.6, and 1.2 nmol) of RvD1 after experimental SAH. Neurological scores, brain edema, and blood-brain barrier integrity were evaluated; besides, neutrophil infiltration, neuronal deaths, and microglial pro-inflammatory polarization were observed using histopathology or immunofluorescence staining, western blots, and qPCR. After confirming the effectiveness of RvD1 in SAH, we administered the FPR2-specific antagonist Trp-Arg-Trp-Trp-Trp-Trp-NH2 (WRW4) 30 min before SAH establishment to observe whether this compound could abolish the anti-inflammatory effect of RvD1. Altogether, our results showed that RvD1 exerted a strong anti-inflammatory effect and markedly reduced neutrophil infiltration and microglial pro-inflammatory activation, leading to remarkable improvements in neurological function and brain tissue restoration. After addition of WRW4, the anti-inflammatory effects of RvD1 were abolished. These results indicated that RvD1 could exert a good anti-inflammatory effect and alleviate EBI, which suggested that RvD1 might be a novel therapeutic alternative for SAH-induced injury.