Early elevation of serum tumor necrosis factor-α is associated with poor outcome in subarachnoid hemorrhage

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

BACKGROUND

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

MATERIALS AND METHODS

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

DISCUSSION

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

TRIAL REGISTRATION

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

Association Between High Preoperative White Blood Cell-to-Hemoglobin Ratio and Postoperative Symptomatic Cerebral Vasospasm in Patients With Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (ASAH) is a serious complication and has a strong relationship with systemic inflammatory responses. Given previously reported relationships between leukocytosis and anemia with ASAH-related cerebral vasospasm, this study examined the association between the preoperative white blood cell-to-hemoglobin ratio (WHR) and postoperative symptomatic cerebral vasospasm (SCV) in patients with ASAH.

METHODS

Demographic, preoperative (comorbidities, ASAH characteristics, laboratory findings), intraoperative (operation and anesthesia), and postoperative (SCV, other neurological complications, clinical course) data were retrospectively analyzed in patients with ASAH who underwent surgical or endovascular treatment of the culprit aneurysm. Patients were divided into high-WHR (n=286) and low-WHR (n=257) groups based on the optimal cutoff value of preoperative WHR (0.74), and stabilized inverse probability weighting was performed between the 2 groups. The predictive power of the WHR and other preoperative systemic inflammatory indices (neutrophil-to-albumin, neutrophil-to-lymphocyte, platelet-to-lymphocyte, platelet-to-neutrophil, platelet-to-white blood cell ratios, and systemic immune-inflammation index) for postoperative SCV was evaluated.

RESULTS

Postoperative SCV was more frequent in the high-WHR group than in the low-WHR group before (33.2% vs. 12.8%; P<0.001) and after (29.4% vs. 19.1%; P=0.005) inverse probability weighting. Before weighting, the predictive power for postoperative SCV was the highest for the WHR among the preoperative systematic inflammatory indices investigated (area under receiver operating characteristics curve 0.66, P<0.001). After weighting, preoperative WHR ≥0.74 was independently associated with postoperative SCV (odds ratio 1.76; P=0.006).

CONCLUSIONS

High preoperative WHR was an independent predictor of postoperative SCV in patients with ASAH.

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

Background

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

Methods

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

Results

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

Conclusion

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

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

Background

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

Materials and methods

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

Discussion

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

Trial registration

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

Common Data Elements for Disorders of Consciousness: Recommendations from the Working Group on Biospecimens and Biomarkers

BACKGROUND

In patients with disorders of consciousness (DoC), laboratory and molecular biomarkers may help define endotypes, identify therapeutic targets, prognosticate outcomes, and guide patient selection in clinical trials. We performed a systematic review to identify common data elements (CDEs) and key design elements (KDEs) for future coma and DoC research.

METHODS

The Curing Coma Campaign Biospecimens and Biomarkers work group, composed of seven invited members, reviewed existing biomarker and biospecimens CDEs and conducted a systematic literature review for laboratory and molecular biomarkers using predetermined search words and standardized methodology. Identified CDEs and KDEs were adjudicated into core, basic, supplemental, or experimental CDEs per National Institutes of Health classification based on level of evidence, reproducibility, and generalizability across different diseases through a consensus process.

RESULTS

Among existing National Institutes of Health CDEs, those developed for ischemic stroke, traumatic brain injury, and subarachnoid hemorrhage were most relevant to DoC and included. KDEs were common to all disease states and included biospecimen collection time points, baseline indicator, biological source, anatomical location of collection, collection method, and processing and storage methodology. Additionally, two disease core, nine basic, 24 supplemental, and 59 exploratory biomarker CDEs were identified. Results were summarized and generated into a Laboratory Data and Biospecimens Case Report Form (CRF) and underwent public review. A final CRF version 1.0 is reported here.

CONCLUSIONS

Exponential growth in biomarkers development has generated a growing number of potential experimental biomarkers associated with DoC, but few meet the quality, reproducibility, and generalizability criteria to be classified as core and basic biomarker and biospecimen CDEs. Identification and adaptation of KDEs, however, contribute to standardizing methodology to promote harmonization of future biomarker and biospecimens studies in DoC. Development of this CRF serves as a basic building block for future DoC studies.

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.

Cortical Spreading Depolarization and Delayed Cerebral Ischemia; Rethinking Secondary Neurological Injury in Subarachnoid Hemorrhage

Poor outcomes in Subarachnoid Hemorrhage (SAH) are in part due to a unique form of secondary neurological injury known as Delayed Cerebral Ischemia (DCI). DCI is characterized by new neurological insults that continue to occur beyond 72 h after the onset of the hemorrhage. Historically, it was thought to be a consequence of hypoperfusion in the setting of vasospasm. However, DCI was found to occur even in the absence of radiographic evidence of vasospasm. More recent evidence indicates that catastrophic ionic disruptions known as Cortical Spreading Depolarizations (CSD) may be the culprits of DCI. CSDs occur in otherwise healthy brain tissue even without demonstrable vasospasm. Furthermore, CSDs often trigger a complex interplay of neuroinflammation, microthrombi formation, and vasoconstriction. CSDs may therefore represent measurable and modifiable prognostic factors in the prevention and treatment of DCI. Although Ketamine and Nimodipine have shown promise in the treatment and prevention of CSDs in SAH, further research is needed to determine the therapeutic potential of these as well as other agents.

Early Systemic Glycolytic Shift After Aneurysmal Subarachnoid Hemorrhage is Associated with Functional Outcomes

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) leads to a robust systemic inflammatory response. We hypothesized that an early systemic glycolytic shift occurs after aSAH, resulting in a unique metabolic signature and affecting systemic inflammation.

METHODS

Control patients and patients with aSAH were analyzed. Samples from patients with aSAH were collected within 24 h of aneurysmal rupture. Mass spectrometry-based metabolomics was performed to assess relative abundance of 16 metabolites involved in the tricarboxylic acid cycle, glycolysis, and pentose phosphate pathway. Principal component analysis was used to segregate control patients from patients with aSAH. Dendrograms were developed to depict correlations between metabolites and cytokines. Analytic models predicting functional outcomes were developed, and receiver operating curves were compared.

RESULTS

A total of 122 patients with aSAH and 38 control patients were included. Patients with aSAH had higher levels of glycolytic metabolites (3-phosphoglycerate/2-phosphoglycerate, lactate) but lower levels of oxidative metabolites (succinate, malate, fumarate, and oxalate). Patients with higher clinical severity (Hunt-Hess Scale score ≥ 4) had higher levels of glyceraldehyde 3-phosphate and citrate but lower levels of α-ketoglutarate and glutamine. Principal component analysis readily segregated control patients from patients with aSAH. Correlation analysis revealed distinct clusters in control patients that were not observed in patients with aSAH. Higher levels of fumarate were associated with good functional outcomes at discharge (odds ratio [OR] 1.76, 95% confidence interval [CI] 1.15-2.82) in multivariable models, whereas higher levels of citrate were associated with poor functional outcomes at discharge (OR 0.36, 95% CI 0.16-0.73) and at 3 months (OR 0.35, 95% CI 0.14-0.81). No associations were found with delayed cerebral ischemia. Levels of α-ketoglutarate and glutamine correlated with lower levels of interleukin-8, whereas fumarate was associated with lower levels of tumor necrosis factor alpha.

CONCLUSIONS

Aneurysmal subarachnoid hemorrhage results in a unique pattern of plasma metabolites, indicating a shift toward glycolysis. Higher levels of fumarate and lower levels of citrate were associated with better functional outcomes. These metabolites may represent targets to improve metabolism after aSAH.

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.

The minor allele of rs17427875 in long non-coding RNA-HOXA11-AS influences the prognosis of subarachnoid hemorrhage (SAH) via modulating miR-15a and STAT3 expression

Background: HOAX11-AS was reported to promote the progression of liver cancer via the signaling pathway of miR-15a-3p/STAT3. In this study, we investigated the effect of rs17427875 on the prognosis of subarachnoid hemorrhage (SAH) and its underlying molecular mechanisms.

Methods: 158 SAH patients were recruited and grouped according to their genotypes rs17427875. Peripheral blood and cerebrospinal fluid (CSF) samples were collected for subsequent analysis. Quantitative real-time PCR, luciferase assays, Western blot and ELISA were performed to analyze the correlations between the expression of lncRNA-HOXA11-AS, miR-15a, TNF-α and NF-κB.

Results: The survival rate was remarkably higher in SAH patients carrying the AA genotype of rs17427875 when compared with those carrying the AT genotype. The expression of miR-15a was significantly repressed in the peripheral blood and CSF of SAH patients carrying the AT allele when compared with that in patients carrying the AA allele. MiR-15a showed a remarkable efficacy in inhibiting the luciferase activity of wild type lncRNA-HOXA11-AS and STAT3 in THP-1 cells. P-HOXA11-AS-T showed a stronger ability to suppress the expression of miR-15a and activate the expression of STAT3, TNF-α and NF-κB in THP-1 cells when compared with P-HOXA11-AS-A.

Conclusions: The findings demonstrated that the presence of the minor allele of rs17427875 in lncRNA-HOXA11-AS could increase the expression level of lncRNA-HOXA11-AS, thus elevating the expression level of STAT3 via down-regulating miR-15a, and increased STAT3 expression could aggravate inflammation to cause poor prognosis of SAH. Therefore, the rs17427875 polymorphism can be used as a potential biomarker for the prognosis of SAH.

2-PMAP Ameliorates Cerebral Vasospasm and Brain Injury after Subarachnoid Hemorrhage by Regulating Neuro-Inflammation in Rats

A subarachnoid hemorrhage (SAH), leading to severe disability and high fatality in survivors, is a devastating disease. Neuro-inflammation, a critical mechanism of cerebral vasospasm and brain injury from SAH, is tightly related to prognoses. Interestingly, studies indicate that 2-[(pyridine-2-ylmethyl)-amino]-phenol (2-PMAP) crosses the blood-brain barrier easily. Here, we investigated whether the vasodilatory and neuroprotective roles of 2-PMAP were observed in SAH rats. Rats were assigned to three groups: sham, SAH and SAH+2-PMAP. SAHs were induced by a cisterna magna injection. In the SAH+2-PMAP group, 5 mg/kg 2-PMAP was injected into the subarachnoid space before SAH induction. The administration of 2-PMAP markedly ameliorated cerebral vasospasm and decreased endothelial apoptosis 48 h after SAH. Meanwhile, 2-PMAP decreased the severity of neurological impairments and neuronal apoptosis after SAH. Furthermore, 2-PMAP decreased the activation of microglia and astrocytes, expressions of TLR-4 and p-NF-κB, inflammatory markers (TNF-α, IL-1β and IL-6) and reactive oxygen species. This study is the first to confirm that 2-PMAP has vasodilatory and neuroprotective effects in a rat model of SAH. Taken together, the experimental results indicate that 2-PMAP treatment attenuates neuro-inflammation, oxidative stress and cerebral vasospasm, in addition to ameliorating neurological deficits, and that these attenuating and ameliorating effects are conferred through the TLR-4/NF-κB pathway.

Systemic immune-inflammation index predicts the outcome after aneurysmal subarachnoid hemorrhage

Systemic inflammatory response is closely related to the pathogenesis and prognosis in critical patients. Recently, systemic immune-inflammation index (SII), an indicator of systemic inflammatory response, was proved to predict the outcome in cancerous and non-cancerous diseases. The aim of this study is to investigate the association between SII on admission and 6-month outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). The clinical data and prognosis of 76 patients with aSAH were analyzed. The 6-month outcome was assessed by the modified Rankin scale(mRS). The unfavorable outcome was defined as mRS score ≥ 3. In addition, multivariate analysis was conducted to investigate factors independently associated with the favorable outcome. Receiver operating characteristic (ROC) curve analysis was undertaken to identify the best cut-off value of SII for the discriminate between favorable and unfavorable outcome in these patients. Thirty-six patients (47.4%) in our study had an unfavorable outcome (mRS ≥ 3) at 6 months, and twenty-four (66.7%) of them were in the high-SII group. A significantly higher SII on admission was observed in patients with unfavorable functional outcome at 6 months. Binary logistic regression analysis showed that there was an independent association between SII on admission and 6-month clinical outcome (adjusted OR = 4.499, 95%CI: 1.242-16.295, P < 0.05). The AUC of the SII for predicting unfavorable outcome was 0.692 (95% CI: 0.571-0.814, P < 0.05). Systemic immune-inflammation index (SII) could be a novel independent prognostic factor for aSAH patients at the early stage of the disease.

CSF lipocalin-2 increases early in subarachnoid hemorrhage are associated with neuroinflammation and unfavorable outcome

Lipocalin-2 mediates neuro-inflammation and iron homeostasis in vascular injuries of the central nervous system (CNS) and is upregulated in extra-CNS systemic inflammation. We postulate that cerebrospinal fluid (CSF) and blood lipocalin-2 levels are associated with markers of inflammation and functional outcome in subarachnoid hemorrhage (SAH). We prospectively enrolled 67 SAH subjects, serially measured CSF and plasma lipocalin-2, matrix metallopeptidase 9 (MMP-9), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) on post-SAH days 1-5 and assessed outcome by modified Rankin Scale (mRS) every 3 months. Unfavorable outcome is defined as mRS > 2. Twenty non-SAH patients undergoing lumbar drain trial were enrolled as controls. Lipocalin-2 was detectable in the CSF and significantly higher in SAH compared to controls (p < 0.0001). Higher CSF LCN2 throughout post-SAH days 1-5 was associated with unfavorable outcome at 3 (p = 0.0031) and 6 months (p = 0.014). Specifically, higher CSF lipocalin-2 on post-SAH days 3 (p = 0.036) and 5 (p = 0.016) were associated with unfavorable 3-month outcome. CSF lipocalin-2 levels positively correlated with CSF IL-6, TNF-α and MMP-9 levels. Higher plasma lipocalin-2 levels over time were associated with worse 6-month outcome. Additional studies are required to understand the role of lipocalin-2 in SAH and to validate CSF lipocalin-2 as a potential biomarker for SAH outcome.

Early Inflammatory Cytokine Expression in Cerebrospinal Fluid of Patients with Spontaneous Intraventricular Hemorrhage

We investigated cerebrospinal fluid (CSF) expression of inflammatory cytokines and their relationship with spontaneous intracerebral and intraventricular hemorrhage (ICH, IVH) and perihematomal edema (PHE) volumes in patients with acute IVH. Twenty-eight adults with IVH requiring external ventricular drainage for obstructive hydrocephalus had cerebrospinal fluid (CSF) collected for up to 10 days and had levels of interleukin-1α (IL-1α), IL-1β, IL-6, IL-8, IL-10, tumor necrosis factor-α (TNFα), and C-C motif chemokine ligand CCL2 measured using enzyme-linked immunosorbent assay. Median [IQR] ICH and IVH volumes at baseline (T0) were 19.8 [5.8–48.8] and 14.3 [5.3–38] mL respectively. Mean levels of IL-1β, IL-6, IL-10, TNF-α, and CCL2 peaked early compared to day 9–10 (p < 0.05) and decreased across subsequent time periods. Levels of IL-1β, IL-6, IL-8, IL-10, and CCL2 had positive correlations with IVH volume at days 3–8 whereas positive correlations with ICH volume occurred earlier at day 1–2. Significant correlations were found with PHE volume for IL-6, IL-10 and CCL2 at day 1–2 and with relative PHE at days 7–8 or 9–10 for IL-1β, IL-6, IL-8, and IL-10. Time trends of CSF cytokines support experimental data suggesting association of cerebral inflammatory responses with ICH/IVH severity. Pro-inflammatory markers are potential targets for injury reduction.

The Pathogenesis of Hydrocephalus Following Aneurysmal Subarachnoid Hemorrhage

Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage (aSAH) and reportedly contributes to poor neurological outcomes. In this review, we summarize the molecular and cellular mechanisms involved in the pathogenesis of hydrocephalus following aSAH and summarize its treatment strategies. Various mechanisms have been implicated for the development of chronic hydrocephalus following aSAH, including alterations in cerebral spinal fluid (CSF) dynamics, obstruction of the arachnoid granulations by blood products, and adhesions within the ventricular system. Regarding molecular mechanisms that cause chronic hydrocephalus following aSAH, we carried out an extensive review of animal studies and clinical trials about the transforming growth factor-β/SMAD signaling pathway, upregulation of tenascin-C, inflammation-dependent hypersecretion of CSF, systemic inflammatory response syndrome, and immune dysregulation. To identify the ideal treatment strategy, we discuss the predictive factors of shunt-dependent hydrocephalus between surgical clipping and endovascular coiling groups. The efficacy and safety of other surgical interventions including the endoscopic removal of an intraventricular hemorrhage, placement of an external ventricular drain, the use of intraventricular or cisternal fibrinolysis, and an endoscopic third ventriculostomy on shunt dependency following aSAH were also assessed. However, the optimal treatment is still controversial, and it necessitates further investigations. A better understanding of the pathogenesis of acute and chronic hydrocephalus following aSAH would facilitate the development of treatments and improve the outcome.

Interleukin 6 and Aneurysmal Subarachnoid Hemorrhage. A Narrative Review

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

Significance of changes in the concentration of inflammatory factors in blood or cerebrospinal fluid in evaluating the severity and prognosis of spontaneous cerebral hemorrhage: A systematic review and meta-analysis

OBJECTIVE

Spontaneous intracerebral hemorrhage (SICH) often leads to severe disability, while inflammation plays an important role in SICH-induced secondary brain injury. The purpose of this study was to investigate the value of inflammatory factors as a means of evaluating the prognosis of SICH and to investigate the relationship between inflammatory factors and the severity and prognosis of SICH.

METHODS

The articles published before November 1 2020 were searched through PubMed, EMBASE, Cochrane library and web of science. Revman5.3 was used, using the inverse variance model to pool the SMD of TNF-a and interleukin concentration.

RESULTS

A total of 25 studies involving 3333 subjects were included in this paper. The concentration of TNF-α in the blood or cerebrospinal fluid of severe SICH patients was significantly higher than that of milder SICH patients or healthy population; SICH patients with high TNF-α concentration had a 1.06 times greater odds of poor outcomes than patients with low TNF-α concentration, odds ratio (OR) = 1.06[95% CI, 1.01-1.12]. The concentration of interleukin-6 (IL-6) in severe SICH patients was significantly higher than that in milder SICH patients; patients with high IL-6 concentration had a 2.61 times greater odds of poor outcomes than patients with low IL-6 concentration, OR = 2.61[95% CI, 1.79-3.80].

CONCLUSIONS

The detection of concentrations of TNF-α and IL-6 in peripheral blood may be helpful for the objective and quantitative assessment of the severity and prognosis of patients with SICH, and have certain significance for the selection of appropriate treatment options.

Association between inflammatory response and outcome after subarachnoid haemorrhage

Objectives

Recent reports suggest an association between the inflammatory response after aneurysmal subarachnoid haemorrhage (aSAH) and patients' outcome. The primary aim of this study was to identify a potential association between the inflammatory response after aSAH and 1‐year outcome. The secondary aim was to investigate whether the inflammatory response after aSAH could predict the development of delayed cerebral ischaemia (DCI).

Materials and methods

This prospective observational pilot study included patients with an aSAH admitted to Sahlgrenska University Hospital, Gothenburg, Sweden, between May 2015 and October 2016. The patients were stratified according to the extended Glasgow Outcome Scale (GOSE) as having an unfavourable (score: 1–4) or favourable outcome (score: 5–8). Furthermore, patients were stratified depending on development of DCI or not. Patient data and blood samples were collected and analysed at admission and after 10 days.

Results

Elevated serum concentrations of inflammatory markers such as tumour necrosis factor‐α and interleukin (IL)‐6, IL‐1Ra, C‐reactive protein and intercellular adhesion molecule‐1 were detected in patients with unfavourable outcome. When adjustments for Glasgow coma scale were made, only IL‐1Ra remained significantly associated with poor outcome (p = 0.012). The inflammatory response after aSAH was not predictive of the development of DCI.

Conclusion

Elevated serum concentrations of inflammatory markers were associated with poor neurological outcome 1‐year after aSAH. However, inflammatory markers are affected by many clinical events, and when adjustments were made, only IL‐1Ra remained significantly associated with poor outcome. The robustness of these results needs to be tested in a larger trial.

The role of immune inflammation in aneurysmal subarachnoid hemorrhage

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

TNF-R1 Correlates with Cerebral Perfusion and Acute Ischemia Following Subarachnoid Hemorrhage

BACKGROUND

Early cerebral hypoperfusion and ischemia occur after subarachnoid hemorrhage (SAH) and influence clinical prognosis. Pathophysiological mechanisms possibly involve inflammatory mediators. TNF-α has been associated with complications and prognosis after SAH. We investigated the relation of perfusion parameters and ischemic lesions, with levels of TNF-α main receptor, TNF-R1, after SAH, and their association with prognosis.

METHODS

We included consecutive SAH patients admitted within the first 72 h of SAH onset. Blood samples were simultaneously collected from a peripheral vein and from the parent artery of the aneurysm. Levels of TNF-R1 were measured using ELISA (R&D Systems Inc., USA). CT perfusion and MRI studies were performed in the first 72 h. Correlation and logistic regression analysis were used to identify outcome predictors.

RESULTS

We analyzed 41 patients. Increased levels of TNF-R1 correlated with increased T_max (arterial: r = -0.37, p = 0.01) and prolonged MTT (arterial: r = 0.355, p = 0.012; venous: r = 0.306, p = 0.026). Increased levels of both arterial and venous TNF-R1 were associated with increased number of lesions on DWI (p = 0.006). In multivariate analysis, venous TNFR1 levels > 1742.2 pg/mL (OR 1.78; 95%CI 1.18-2.67; p = 0.006) and DWI lesions (OR 14.01; 95%CI 1.19-165.3; p = 0.036) were both independent predictors of poor outcome (mRS ≥ 3) at 6 months.

CONCLUSION

Increased levels of TNF-R1 in arterial and venous blood correlate with worse cerebral perfusion and with increased burden of acute ischemic lesions in the first 72 h after SAH. Venous levels of TNF-R1 and DWI lesions were associated with poor outcome at 6 months. These results highlight the pathophysiological role of TNF-α pathways in SAH and suggest a possible role of combined imaging and laboratorial markers in determining prognosis in acute SAH.

The Role of Long Non-Coding RNAs in Intracranial Aneurysms and Subarachnoid Hemorrhage

Intracranial aneurysms (IAs) represent the most complex and relevant problem of modern neurology and neurosurgery. They serve as one of the main causes of non-traumatic subarachnoid hemorrhage (SAH), causing up to 85% of all cases of intracranial hemorrhage, which is associated with frequent disability and high mortality among patients. Unfortunately, the molecular mechanisms of the development and rupture of IAs are still under study. Long non-coding RNAs (lncRNAs) are non-coding RNAs that typically have a length of more than 200 nucleotides. It is known that lncRNAs regulate many processes, such as transcription, translation, cell differentiation, regulation of gene expression, and regulation of the cell cycle. In recent years, a lot of evidence has established their role in human diseases from oncology to cardiovascular disease. Recent studies have shown that lncRNAs may be involved in the pathogenesis of IAs. The study of lncRNAs and its targets in various pathological conditions of a person is a rapidly developing field, and it is likely that the knowledge obtained from these studies regarding the pathogenesis of intracranial aneurysms will have the potential to use lncRNAs in therapy, as well as in the diagnosis and prediction of high aneurysms risk of rupture.

Preliminary results in the analysis of the immune response after aneurysmal subarachnoid hemorrhage

Cerebral vasospasm (VSP) is a common phenomenon after aneurysmal subarachnoid hemorrhage (aSAH) and contributes to neurocognitive decline. The natural history of the pro-inflammatory immune response after aSAH has not been prospectively studied in human cerebrospinal fluid (CSF). In this pilot study, we aimed to identify specific immune mediators of VSP after aSAH. Peripheral blood (PB) and CSF samples from patients with aSAH were prospectively collected at different time-points after hemorrhage: days 0–1 (acute); days 2–4 (pre-VSP); days 5–9 (VSP) and days 10 + (post-VSP peak). Presence and severity of VSP was assessed with computed tomography angiography/perfusion imaging and clinical examination. Cytokine and immune mediators’ levels were quantified using ELISA. Innate and adaptive immune cells were characterized by flow cytometry, and cell counts at different time-points were compared with ANOVA. Confocal immunostaining was used to determine the presence of specific immune cell populations detected in flow cytometry. Thirteen patients/aneurysms were included. Five (38.5%) patients developed VSP after a mean of 6.8 days from hemorrhage. Flow cytometry demonstrated decreased numbers of CD45+ cells during the acute phase in PB of aSAH patients compared with healthy controls. In CSF of VSP patients, NK cells (CD3-CD161 +) were increased during the acute phase and progressively declined, whereas CD8+CD161+ lymphocytes significantly increased at days 5–9. Microglia cells (CD45dimCD11b +) increased over time after SAH. This increase was particularly significant in patients with VSP. Levels of VEGF and MMP-9 were consistently higher in VSP patients, with the highest difference occurring at the acute phase. Confocal immunostaining demonstrated the presence of CD8+CD161+ lymphocytes in the arterial wall of two unruptured intracranial aneurysms. In this preliminary study, human CSF showed active presence of innate and adaptive immune cells after aSAH. CD8+CD161+ lymphocytes may have an important role in the inflammatory response after aneurysmal rupture and were identified in the aneurysmal wall of unruptured brain aneurysms. Microglia activation occurs 6 + days after aSAH.

Soluble vascular endothelial-cadherin in CSF after subarachnoid hemorrhage

OBJECTIVE

To determine if CSF and plasma levels of soluble vascular endothelial (sVE)-cadherin are associated with functional outcome after subarachnoid hemorrhage (SAH) and to investigate sVE-cadherin effects on microglia.

METHODS

Serial CSF and plasma were collected from prospectively enrolled patients with nontraumatic SAH from a ruptured aneurysm in the anterior circulation and who required an external ventricular drain for clinical indications. Patients with normal-pressure hydrocephalus without SAH served as controls. For prospective assessment of long-term outcomes at 3 and 6 months after SAH, modified Rankin Scale scores (mRS) were obtained and dichotomized into good (mRS ≤ 2) vs poor (mRS > 2) outcome groups. For SAH severity, Hunt and Hess grade was assessed. Association of CSF sVE-cadherin levels with long-term outcomes, HH grade, and CSF tumor necrosis factor (TNF)-α levels were evaluated. sVE-cadherin effects on microglia were also studied.

RESULTS

sVE-cadherin levels in CSF, but not in plasma, were higher in patients with SAH and were associated with higher clinical severity and higher CSF TNF-α levels. Patients with SAH with higher CSF sVE-cadherin levels over time were more likely to develop worse functional outcome at 3 months after SAH. Incubation of cultured microglia with sVE-cadherin resulted in increased inducible nitric oxide synthase, interleukin-1β, reactive oxygen species, cell soma size, and metabolic activity, consistent with microglia activation. Microinjection of sVE-cadherin fragments into mouse brain results in an increased number of microglia surrounding the injection site, compared to injection of denatured vascular endothelial-cadherin fragments.

CONCLUSIONS

These results support the existence of a novel pathway by which sVE-cadherin, released from injured endothelium after SAH, can shift microglia into a more proinflammatory phenotype and contribute to neuroinflammation and poor outcome in SAH.

Biospecimens and Molecular and Cellular Biomarkers in Aneurysmal Subarachnoid Hemorrhage Studies: Common Data Elements and Standard Reporting Recommendations

INTRODUCTION

Development of clinical biomarkers to guide therapy is an important unmet need in aneurysmal subarachnoid hemorrhage (SAH). A wide spectrum of plausible biomarkers has been reported for SAH, but none have been validated due to significant variabilities in study design, methodology, laboratory techniques, and outcome endpoints.

METHODS

A systematic review of SAH biomarkers was performed per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The panel's recommendations focused on harmonization of (1) target cellular and molecular biomarkers for future investigation in SAH, (2) standardization of best-practice procedures in biospecimen and biomarker studies, and (3) experimental method reporting requirements to facilitate meta-analyses and future validation of putative biomarkers.

RESULTS

No cellular or molecular biomarker has been validated for inclusion as "core" recommendation. Fifty-four studies met inclusion criteria and generated 33 supplemental and emerging biomarker targets. Core recommendations include best-practice protocols for biospecimen collection and handling as well as standardized reporting guidelines to capture the heterogeneity and variabilities in experimental methodologies and biomarker analyses platforms.

CONCLUSION

Significant variabilities in study design, methodology, laboratory techniques, and outcome endpoints exist in SAH biomarker studies and present significant barriers toward validation and translation of putative biomarkers to clinical use. Adaptation of common data elements, recommended biospecimen protocols, and reporting guidelines will reduce heterogeneity and facilitate future meta-analyses and development of validated clinical biomarkers in SAH.

Recent Advances in Stem Cell Research in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke with significant morbidity and mortality, and it often leads to poor clinical outcome. Although great efforts have been made toward animal and clinical studies, optimal therapy of SAH remains a challenge for scientists and clinicians. Increasing evidence suggests that stem-cell-based therapies may provide innovative approaches for treatment of SAH-related disability. In this review, we summarized the recent advances in stem cell research in SAH. Neuroregeneration after SAH could be conducted by the activation of endogenous neural stem cells (NSCs), transplantation of external stem cells, or reprogramming non-neuronal cell to neurons. The potential mechanism and signaling pathways, as well as the efficiency and safety of these stem cell treatments, were discussed in detail. Although lots of challenges remain for translating the laboratory findings and technologies into clinical therapies, these research studies provided the foundation and guidance for using different resources of stem cells as a brain repair strategy after SAH.

Systemic High-Mobility Group Box-1: A Novel Predictive Biomarker for Cerebral Vasospasm in Aneurysmal Subarachnoid Hemorrhage

OBJECTIVES

To investigate the release of proinflammatory damage-associated molecular pattern molecule "high-mobility group box-1" in the serum of patients after aneurysmal subarachnoid hemorrhage and its association with cerebral vasospasm.

DESIGN

Retrospective observational study.

SETTING

University hospital.

PATIENTS

Aneurysmal subarachnoid hemorrhage patients admitted within 24 hours of ictus.

INTERVENTIONS

Standard subarachnoid hemorrhage treatment after clipping or coiling of aneurysm.

MEASUREMENTS AND MAIN RESULTS

We enrolled 53 aneurysmal subarachnoid hemorrhage patients from which peripheral venous blood was withdrawn on days 1, 3, 5, 7, 9, 11, and 13 and once from the controls to obtain the serum. Serum high-mobility group box-1 concentration was quantified by enzyme-linked immunosorbent assay. Serum interleukin-6 and peripheral blood leukocytes were also determined over the first 2 weeks after subarachnoid hemorrhage. Patients' data were recorded prospectively. Serum high-mobility group box-1 was significantly elevated in subarachnoid hemorrhage patients from day 1 to day 13 when compared with nonsubarachnoid hemorrhage patients (p < 0.05). Patients with cerebral vasospasm showed significantly higher high-mobility group box-1 starting from day 1 to day 13 when compared with patients without cerebral vasospasm. Cumulative levels of high-mobility group box-1 showed significant correlation with peripheral blood leukocytes and interleukin-6 levels (p < 0.05). Receiver operating characteristic curve analysis showed that serum high-mobility group box-1 level at admission may be a predictive biomarker for cerebral vasospasm with a sensitivity of 59% and a specificity of 82% at a cutoff value of 5.6 ng/mL.

CONCLUSIONS

Serum high-mobility group box-1 is differentially elevated after subarachnoid hemorrhage. Serum high-mobility group box-1 levels were elevated early after subarachnoid hemorrhage (day 1) and remained significantly high until day 13 in patients who developed cerebral vasospasm. Our data suggest that serum high-mobility group box-1 may be a predictive biomarker for the detection of CVS.

Role of ATP-sensitive potassium channels and inflammatory response of basilar artery smooth muscle cells in subarachnoid hemorrhage of rabbit and immune-modulation by shikonin

OBJECTIVE

To investigate the role of inflammatory response, oxidative damage and changes of ATP-sensitive potassium channels (sK_ATP) in basilar artery (BA) smooth muscle cells (SMCS) of rabbits in subarachnoid hemorrhage (SAH) model.

METHODS

Time course studies on inflammatory response by real-time PCR, oxidative process and function of isolated basilar artery after SAH in New Zealand White rabbits were performed. Basilar artery smooth muscle cells (BASMCs) in each group were obtained and whole-cell patch-clamp technique was applied to record cell membrane capacitance and K_ATP currents. The morphologies of basal arteries were analyzed. Protective effect of shikonin were also determine by same parameters.

RESULTS

Inflammatory cytokines levels were highest at 24h compare to 72h after SAH whereas the oxidative damage and cell death marker were at highest peak at 72h. Oxidative damage peak coincided with significant alterations in cell membrane capacitance, K_ATP currents and morphological changes in basilar arteries. Shikokin pretreatment attenuated early inflammatory response at 24h and associated oxidative damage at 72h. Finally, shikonin attenuated morphological changes in basilar arteries and dysfunction.

CONCLUSION

Currents of ATP-sensitive potassium channels in basilar smooth muscle cells decreased after SAH by putative oxidative modification from immediate inflammatory response and can be protected by shikonin pretreatment.

Systemic inflammation in hemorrhagic strokes - A novel neurological sign and therapeutic target?

Growing evidences suggest that stroke is a systemic disease affecting many organ systems beyond the brain. Stroke-related systemic inflammatory response and immune dysregulations may play an important role in brain injury, recovery, and stroke outcome. The two main phenomena in stroke-related peripheral immune dysregulations are systemic inflammation and post-stroke immunosuppression. There is emerging evidence suggesting that the spleen contracts following ischemic stroke, activates peripheral immune response and this may further potentiate brain injury. Whether similar brain-immune crosstalk occurs in hemorrhagic strokes such as intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) is not established. In this review, we systematically examined animal and human evidence to date on peripheral immune responses associated with hemorrhagic strokes. Specifically, we reviewed the impact of clinical systemic inflammatory response syndrome (SIRS), inflammation- and immune-associated biomarkers, the brain-spleen interaction, and cellular mediators of peripheral immune responses to ICH and SAH including regulatory T cells (Tregs). While there is growing data suggesting that peripheral immune dysregulation following hemorrhagic strokes may be important in brain injury pathogenesis and outcome, details of this brain-immune system cross-talk remain insufficiently understood. This is an important unmet scientific need that may lead to novel therapeutic strategies in this highly morbid condition.

Resveratrol reduces brain injury after subarachnoid hemorrhage by inhibiting oxidative stress and endoplasmic reticulum stress

Previous studies have shown that resveratrol, a bioactive substance found in many plants, can reduce early brain injury after subarachnoid hemorrhage, but how it acts is still unclear. This study explored the mechanism using the experimental subarachnoid hemorrhage rat model established by injecting autologous blood into the cerebellomedullary cistern. Rat models were treated with an intraperitoneal injection of 60 mg/kg resveratrol 2, 6, 24 and 46 hours after injury. At 48 hours after injury, their neurological function was assessed using a modified Garcia score. Brain edema was measured by the wet-dry method. Neuronal apoptosis in the prefrontal cortex was detected by terminal deoxyribonucleotidyl transferase-mediated biotin-16-dUTP nick-end labeling assay. Levels of reactive oxygen species and malondialdehyde in the prefrontal cortex were determined by colorimetry. CHOP, glucose-regulated protein 78, nuclear factor-erythroid 2-related factor 2 and heme oxygenase-1 mRNA expression levels in the prefrontal cortex were measured by reverse transcription polymerase chain reaction. Tumor necrosis factor-alpha content in the prefrontal cortex was detected by enzyme linked immunosorbent assay. Immunohistochemical staining was used to detect the number of positive cells of nuclear factor-erythroid 2-related factor 2, heme oxygenase 1, glucose-regulated protein 78, CHOP and glial fibrillary acidic protein. Western blot assay was utilized to analyze the expression levels of nuclear factor-erythroid 2-related factor 2, heme oxygenase 1, glucose-regulated protein 78 and CHOP protein expression levels in the prefrontal cortex. The results showed that resveratrol treatment markedly alleviated neurological deficits and brain edema in experimental subarachnoid hemorrhage rats, and reduced neuronal apoptosis in the prefrontal cortex. Resveratrol reduced the levels of reactive oxygen species and malondialdehyde, and increased the expression of nuclear factor-erythroid 2-related factor 2, heme oxygenase-1 mRNA and protein in the prefrontal cortex. Resveratrol decreased glucose-regulated protein 78, CHOP mRNA and protein expression and tumor necrosis factor-alpha level. It also activated astrocytes. The results suggest that resveratrol exerted neuroprotective effect on subarachnoid hemorrhage by reducing oxidative damage, endoplasmic reticulum stress and neuroinflammation. The study was approved by the Animals Ethics Committee of Shandong University, China on February 22, 2016 (approval No. LL-201602022).

Red Cell Distribution Width After Subarachnoid Hemorrhage

BACKGROUND

High red cell distribution width (RDW) values have been associated with increased hospital mortality in critically ill patients, but few data are available for subarachnoid hemorrhage (SAH).

METHODS

We analyzed an institutional database of adult (>18 y) patients admitted to the Department of Intensive Care after nontraumatic SAH between January 2011 and May 2016. RDW (normal value, 10.9% to 13.4%) was obtained daily from admission for a maximum of 7 days, from routine blood analysis. We recorded the occurrence of delayed cerebral ischemia (DCI), and neurological outcome (assessed using the Glasgow Outcome Scale [GOS]) at 3 months.

RESULTS

A total of 270 patients were included (median age 54 y-121/270 male [45%]), of whom 96 (36%) developed DCI and 109 (40%) had an unfavorable neurological outcome (GOS, 1 to 3). The median RDW on admission was 13.8 [13.3 to 14.5]% and the highest value during the intensive care unit (ICU) stay 14.2 [13.6 to 14.8]%. The RDW was high (>13.4%) in 177 patients (66%) on admission and in 217 (80%) at any time during the ICU stay. Patients with a high RDW on admission were more likely to have an unfavorable neurological outcome. In multivariable regression analysis, older age, a high WFNS grade on admission, presence of DCI or intracranial hypertension, previous neurological disease, vasopressor therapy and a high RDW (OR, 1.1618 [95% CI, 1.213-2.158]; P=0.001) during the ICU stay were independent predictors of unfavorable neurological outcome.

CONCLUSIONS

High RDW values were more likely to result in an unfavorable outcome after SAH. This information could help in the stratification of SAH patients already on ICU admission.

The role of inflammation and potential use of sex steroids in intracranial aneurysms and subarachnoid hemorrhage

Background

Aneurysmal subarachnoid hemorrhage (aSAH) continues to be a devastating neurological condition with a high risk of associated morbidity and mortality. Inflammation has been shown to increase the risk of complications associated with aSAH such as vasospasm and brain injury in animal models and humans. The goal of this review is to discuss the inflammatory mechanisms of aneurysm formation, rupture and vasospasm and explore the role of sex hormones in the inflammatory response to aSAH.

Methods

A literature review was performed using PubMed using the following search terms: "intracranial aneurysm," "cerebral aneurysm," "dihydroepiandrosterone sulfate" "estrogen," "hormone replacement therapy," "inflammation," "oral contraceptive," "progesterone," "sex steroids," "sex hormones" "subarachnoid hemorrhage," "testosterone." Only studies published in English language were included in the review.

Results

Studies have shown that administration of sex hormones such as progesterone and estrogen at early stages in the inflammatory cascade can lower the risk and magnitude of subsequent complications. The exact mechanism by which these hormones act on the brain, as well as their role in the inflammatory cascade is not fully understood. Moreover, conflicting results have been published on the effect of hormone replacement therapy in humans. This review will scrutinize the variations in these studies to provide a more detailed understanding of sex hormones as potential therapeutic agents for intracranial aneurysms and aSAH.

Conclusion

Inflammation may play a role in the pathogenesis of intracranial aneurysm formation and subarachnoid hemorrhage, and administration of sex hormones as anti-inflammatory agents has been associated with improved functional outcome in experimental models. Further studies are needed to determine the therapeutic role of these hormones in the intracranial aneurysms and aSAH.

Unique Contribution of Haptoglobin and Haptoglobin Genotype in Aneurysmal Subarachnoid Hemorrhage

Survivors of cerebral aneurysm rupture are at risk for significant morbidity and neurological deficits. Much of this is related to the effects of blood in the subarachnoid space which induces an inflammatory cascade with numerous downstream consequences. Recent clinical trials have not been able to reduce the toxic effects of free hemoglobin or improve clinical outcome. One reason for this may be the inability to identify patients at high risk for neurologic decline. Recently, haptoglobin genotype has been identified as a pertinent factor in diabetes, sickle cell, and cardiovascular disease, with the Hp 2-2 genotype contributing to increased complications. Haptoglobin is a protein synthesized by the liver that binds free hemoglobin following red blood cell lysis, and in doing so, prevents hemoglobin induced toxicity and facilitates clearance. Clinical studies in patients with subarachnoid hemorrhage indicate that Hp 2-2 patients may be a high-risk group for hemorrhage related complications and poor outcome. We review the relevance of haptoglobin in subarachnoid hemorrhage and discuss the effects of genotype and expression levels on the known mechanisms of early brain injury (EBI) and cerebral ischemia after aneurysm rupture. A better understanding of haptoglobin and its role in preventing hemoglobin related toxicity should lead to novel therapeutic avenues.

Levels of Interleukin-1β, Interleukin-18, and Tumor Necrosis Factor-α in Cerebrospinal Fluid of Aneurysmal Subarachnoid Hemorrhage Patients May Be Predictors of Early Brain Injury and Clinical Prognosis

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe cerebrovascular accident with high morbidity and mortality. The aim of this study is to investigate the relationship between level of inflammatory cytokines in cerebrospinal fluid (CSF) of aSAH patients, the severity of aSAH, and the outcome of aSAH patients.

METHODS

aSAH patients were prospectively included and followed-up for 6 months. CSF samples were collected at 1-3, 4-6, and 7-9 days after aSAH onset. Levels of interleukin (IL)-1β, IL-18, and tumor necrosis factor-α (TNF-α) in the CSF of aSAH patients were measured by enzyme-linked immunosorbent assay.

RESULTS

Eighty-one aSAH patients were enrolled. The levels of IL-1β, IL-18 and TNF-α in the CSF were especially higher in the group of aSAH patients with cerebral edema, cerebral vasospasm, and a high grade on Hunt-Hess scale, the high World Federation of Neurological Surgeons grades, and Fisher grade (P < 0.01). Higher levels of plasma C-reactive protein in the blood were correlated with poor outcome. The areas under the receiver operating characteristic curves for the levels of inflammatory cytokines in CSF were 0.85, 0.84, and 0.95, respectively. Clinical features (age, Hunt-Hess grade, etc.) were positively correlated with poor outcomes (P < 0.05).

CONCLUSIONS

The levels of IL-1β, IL-18, and TNF-α in CSF were elevated in aSAH patients and were positively associated with cerebral edema and acute hydrocephalus. Our findings suggest that CSF inflammatory cytokines might be biomarkers to assess severity and predict outcomes.

The Role of Platelet Activation and Inflammation in Early Brain Injury Following Subarachnoid Hemorrhage

BACKGROUND

Early brain injury (EBI) following aneurysmal subarachnoid hemorrhage (SAH) is an important predictor of poor functional outcome, yet the underlying mechanism is not well understood. Animal studies suggest that platelet activation and inflammation with subsequent microthrombosis and ischemia may be a mechanism of EBI.

METHODS

A prospective, hypothesis-driven study of spontaneous, SAH patients and controls was conducted. Platelet activation [thromboelastography maximum amplitude (MA)] and inflammation [C-reactive protein (CRP)] were measured serially over time during the first 72 h following SAH onset. Platelet activation and inflammatory markers were compared between controls and SAH patients with mild [Hunt-Hess (HH) 1-3] versus severe (HH 4-5) EBI. The association of these biomarkers with 3-month functional outcomes was evaluated.

RESULTS

We enrolled 127 patients (106 SAH; 21 controls). Platelet activation and CRP increased incrementally with worse EBI/HH grade, and both increased over 72 h (all P < 0.01). Both were higher in severe versus mild EBI (MA 68.9 vs. 64.8 mm, P = 0.001; CRP 12.5 vs. 1.5 mg/L, P = 0.003) and compared to controls (both P < 0.003). Patients with delayed cerebral ischemia (DCI) had more platelet activation (66.6 vs. 64.9 in those without DCI, P = 0.02) within 72 h of ictus. At 3 months, death or severe disability was more likely with higher levels of platelet activation (mRS4-6 OR 1.18, 95 % CI 1.05-1.32, P = 0.007) and CRP (mRS4-6 OR 1.02, 95 % CI 1.00-1.03, P = 0.041).

CONCLUSIONS

Platelet activation and inflammation occur acutely after SAH and are associated with worse EBI, DCI and poor 3-month functional outcomes. These markers may provide insight into the mechanism of EBI following SAH.

The Role of Thromboinflammation in Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a major determinant of patient outcome following aneurysmal subarachnoid hemorrhage. Although the exact mechanisms leading to DCI are not fully known, inflammation, cerebral vasospasm, and microthrombi may all function together to mediate the onset of DCI. Indeed, inflammation is tightly linked with activation of coagulation and microthrombi formation. Thromboinflammation is the intersection at which inflammation and thrombosis regulate one another in a feedforward manner, potentiating the formation of thrombi and pro-inflammatory signaling. In this review, we will explore the role(s) of inflammation and microthrombi in subarachnoid hemorrhage (SAH) pathophysiology and DCI, and discuss the potential of targeting thromboinflammation to prevent DCI after SAH.

Curcumin mitigates cerebral vasospasm and early brain injury following subarachnoid hemorrhage via inhibiting cerebral inflammation

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH)-induced cerebral vasospasm and early brain injury is a fatal clinical syndrome. Cerebral vasospasm and early brain injury are associated with inflammatory response and oxidative stress. Whether curcumin, which plays important roles to regulate inflammatory cytokines and inhibit oxidative stress, inhibits SAH-induced inflammation and oxidative stress are largely unknown.

METHODS

Adult male rats underwent autologous blood injection into prechiasmatic cistern to induce SAH. Curcumin (150 mg/kg) was administered at 0.5, 24 and 48 hr post-SAH. Mortality calculation and neurological outcomes as well as morphological vasospasm of anterior cerebral artery were studied. Superoxide dismutase, lipid peroxidation, and inflammatory cytokines (MCP-1 and TNF-α) expression in prefrontal region were quantified. Furthermore, p65 and phosphor-p65 were quantitatively analyzed.

RESULTS

Curcumin remarkedly reduced mortality and ameliorated neurological deficits after SAH induction (p < .05); morphological results showed that cerebral vasospasm in curcumin-treated group was mitigated (p < .05). SAH-induced MCP-1 and TNF-α overexpression were inhibited in curcumin-treated group (p < .05). Importantly, phosphor-p65 was significantly inhibited after curcumin treatment (p < .05).

CONCLUSIONS

Curcumin can inhibit SAH-induced inflammatory response via restricting NF-κB activation to alleviate cerebral vasospasm and early brain injury.

Emerging Markers of Early Brain Injury and Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage is characterized by a highly complex pathophysiology and results in neurologic deterioration after the inciting bleed. Despite its significant consequences, prompt diagnosis can be elusive and treatment is often administered too late. Early brain injury, which occurs within the first 72 hours after ictus, may be an important factor for delayed cerebral ischemia and poor overall outcome. Here, we explore the purported clinical and pathologic manifestations of early brain injury to identify biomarkers that could have prognostic value.

METHODS

We review the literature and discuss potential emerging markers of delayed cerebral ischemia in the context of early brain injury.

RESULTS

The following clinical features and biomarkers were examined: global cerebral edema, ictal loss of consciousness, ultra early angiographic vasospasm, continuous electroencephalogram monitoring, systemic inflammatory response syndrome, cellular mediators of the inflammatory response, and hematologic derangements.

CONCLUSIONS

Some of these markers possess independent value for determining the risk of complications after aneurysmal subarachnoid hemorrhage. However, their use is limited because of a variety of factors, but they do provide an avenue of further study to aid in diagnosis and management.

Heparin and Heparin-Derivatives in Post-Subarachnoid Hemorrhage Brain Injury: A Multimodal Therapy for a Multimodal Disease

Pharmacologic efforts to improve outcomes following aneurysmal subarachnoid hemorrhage (aSAH) remain disappointing, likely owing to the complex nature of post-hemorrhage brain injury. Previous work suggests that heparin, due to the multimodal nature of its actions, reduces the incidence of clinical vasospasm and delayed cerebral ischemia that accompany the disease. This narrative review examines how heparin may mitigate the non-vasospastic pathological aspects of aSAH, particularly those related to neuroinflammation. Following a brief review of early brain injury in aSAH and heparin’s general pharmacology, we discuss potential mechanistic roles of heparin therapy in treating post-aSAH inflammatory injury. These roles include reducing ischemia-reperfusion injury, preventing leukocyte extravasation, modulating phagocyte activation, countering oxidative stress, and correcting blood-brain barrier dysfunction. Following a discussion of evidence to support these mechanistic roles, we provide a brief discussion of potential complications of heparin usage in aSAH. Our review suggests that heparin’s use in aSAH is not only safe, but effectively addresses a number of pathologies initiated by aSAH.

Neuroinflammation responses after subarachnoid hemorrhage: A review

Subarachnoid hemorrhage (SAH) is an important cause of stroke mortality and morbidity, especially in the young stroke population. Recent evidences indicate that neuroinflammation plays a critical role in both early brain injury and the delayed brain deterioration after SAH, including cellular and molecular components. Cerebral vasospasm (CV) can lead to death after SAH and independently correlated with poor outcome. Neuroinflammation is evidenced to contribute to the etiology of vasospasm. Besides, systemic inflammatory response syndrome (SIRS) commonly occurs in the SAH patients, with the presence of non-infectious fever and systematic complications. In this review, we summarize the evidences that indicate the prominent role of inflammation in the pathophysiology of SAH. That may provide the potential implications on diagnostic and therapeutic strategies.

Ethyl Pyruvate Attenuates Early Brain Injury Following Subarachnoid Hemorrhage in the Endovascular Perforation Rabbit Model Possibly Via Anti-inflammation and Inhibition of JNK Signaling Pathway

Early brain injury (EBI) following subarachnoid hemorrhage (SAH) is the main cause to poor outcomes of SAH patients, and early inflammation plays an important role in the acute pathophysiological events. It has been demonstrated that ethyl pyruvate (EP) has anti-inflammatory and neuroprotective effects in various critical diseases, however, the role of EP on EBI following SAH remains to be elucidated. Our study aimed to evaluate the effects of EP on EBI following SAH in the endovascular perforation rabbit model. All rabbits were randomly divided into three groups: sham, SAH + Vehicle (equal volume) and SAH + EP (30 mg/kg/day). MRI was performed to estimate the reliability of the EBI at 24 and 72 h after SAH. Neurological scores were recorded to evaluate the neurological deficit, ELISA kit was used to measure the level of tumor necrosis factor-α (TNF-α), and western blot was used to detect the expression of TNF-α, tJNK, pJNK, bax and bcl-2 at 24 and 72 h after SAH. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Fluoro-jade B (FJB) staining were used to detect neuronal apoptosis and neurodegeneration respectively, meanwhile hematoxylin and eosin (H&E) staining was used to assess the degree of vasospasm. Our results demonstrated that EP alleviated brain tissue injury (characterized by diffusion weighted imaging and T2 sequence in MRI scan), and significantly improved neurological scores at 72 h after SAH. EP decreased the level of TNF-α and downregulated pJNK/tJNK and bax/bcl-2 in cerebral cortex and hippocampus effectively both at 24 and 72 h after SAH. Furthermore, EP reduced TUNEL and FJB positive cells significantly. In conclusion, the present study supported that EP afforded neuroprotective effects possibly via reducing TNF-α expression and inhibition of the JNK signaling pathway. Therefore, EP may be a potent therapeutic agent to attenuate EBI following SAH.

Inhibition of the Receptor for Advanced Glycation End-Products (RAGE) Attenuates Neuroinflammation While Sensitizing Cortical Neurons Towards Death in Experimental Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a threatening and devastating neurological insult with high mortality and morbidity rates. Despite considerable efforts, the underlying pathophysiological mechanisms are still poorly understood. The receptor for advanced glycation end products (RAGE) is a multiligand receptor that has been implicated in various pathological conditions. We previously showed that RAGE was upregulated and may be involved in pathophysiology of SAH. In the current study, we investigated its potential role in SAH. We found that the upregulation of RAGE after SAH was NF-κB-dependent positive feedback regulation. Further, pharmacological inhibition of RAGE attenuated neuroinflammation, indicating a possible contributive role of RAGE in inflammation-associated brain injury after SAH. Conversely, however, inhibition of RAGE sensitized neurons, exacerbating cell death, which correlated with augmented apoptosis and diminished autophagy, suggesting that activation of RAGE may protect against SAH-induced neuronal injury. Furthermore, we demonstrate that inhibition of RAGE significantly reduced brain edema and improved neurological function at day 1 but not at day 3 post-SAH. Taken together, these results suggest that RAGE exerts dual role after SAH. Our findings also suggest caution should be exercised in setting RAGE-targeted treatment for SAH.

Risk Factors for Cerebral Vasospasm Following Aneurysmal Subarachnoid Hemorrhage: A Review of the Literature

OBJECTIVE

To examine the literature on risk factors for cerebral vasospasm (CV), one of the most serious complications following aneurysmal subarachnoid hemorrhage (SAH), with special reference to the definition of CV.

METHODS

Using standard search engines, including PubMed, the medical literature on risk factors for CV after SAH was reviewed, and the best definition representative of CV was searched.

RESULTS

Severe SAH evident on computed tomography scan was the only consistent risk factor for CV after SAH. Effects of risk factors on CV, including age, clinical grade, rebleeding, intraventricular or intracerebral hemorrhage on computed tomography scan, acute hydrocephalus, aneurysm site and size, leukocytosis, interleukin-6 level, and cardiac abnormalities, appeared to be associated with the severity of SAH rather than each having a direct effect. Cigarette smoking, hypertension, and left ventricular hypertrophy on electrocardiogram were associated with CV without any relationship to SAH severity. With regard to parameters representative of CV, the grade of angiographic vasospasm (i.e., the degree of arterial narrowing evident on angiography) was the most adequate. Nevertheless, few reports on the risk factors associated with angiographic vasospasm grade have been reported to date.

CONCLUSIONS

Severe SAH evident on computed tomography scan appears to be a definite risk factor for CV after SAH, followed by cigarette smoking, hypertension, and left ventricular hypertrophy on electrocardiogram. To understand the pathogenesis of CV, further studies on the relationships between risk factors, especially factors not related to the severity of SAH, and angiographic vasospasm grade are necessary.

Microglia inflict delayed brain injury after subarachnoid hemorrhage

Inflammatory changes have been postulated to contribute to secondary brain injury after aneurysmal subarachnoid hemorrhage (SAH). In human specimens after SAH as well as in experimental SAH using mice, we show an intracerebral accumulation of inflammatory cells between days 4 and 28 after the bleeding. Using bone marrow chimeric mice allowing tracing of all peripherally derived immune cells, we confirm a truly CNS-intrinsic, microglial origin of these immune cells, exhibiting an inflammatory state, and rule out invasion of myeloid cells from the periphery into the brain. Furthermore, we detect secondary neuro-axonal injury throughout the time course of SAH. Since neuronal cell death and microglia accumulation follow a similar time course, we addressed whether the occurrence of activated microglia and neuro-axonal injury upon SAH are causally linked by depleting microglia in vivo. Given that the amount of neuronal cell death was significantly reduced after microglia depletion, we conclude that microglia accumulation inflicts secondary brain injury after SAH.