Early events after aneurysmal subarachnoid hemorrhage

Early Hydrogen-Oxygen Gas Mixture Inhalation in Patients with Aneurysmal Subarachnoid Hemorrhage (HOMA): study protocol for a randomized controlled trial

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening neurosurgical emergency with a high mortality rate. Delayed cerebral ischemia (DCI) and cerebral vasospasm (CVS) are delayed products of early brain injury (EBI), which may constitute the principal determinant of an unfavorable patient prognosis. Consequently, the mitigation of DCI and CVS assumes paramount significance in the pursuit of enhanced patient outcomes. However, except for oral nimodipine, there is no effective therapy available in the current guideline. Hence, the exigency arises to proffer novel treatment paradigms. The diversity of hydrogen therapeutic targets has been largely reported in basic research, unveiling its latent capacity to ameliorate EBI in aSAH patients.

METHODS

Early Hydrogen-Oxygen Gas Mixture Inhalation in Patients with Aneurysmal Subarachnoid Hemorrhage (HOMA), a single-center, prospective, open-labeled, randomized controlled clinical trial, endeavors to evaluate the efficacy and safety of hydrogen-oxygen gas mixture inhalation therapy in aSAH patients. A cohort of 206 patients will be randomized to either hydrogen-oxygen gas mixture inhalation group (8 h per day, 3 L/min, hydrogen concentration of 67%, oxygen concentration of 33%) or oxygen inhalation group (8 h per day, 3 L/min, oxygen concentration of 33%) within 72 h after aSAH and treated for 7 days in the ICU ward. The primary outcomes are the incidence of DCI and CVS during hospitalization.

DISCUSSION

The HOMA aims to evaluate the effectiveness of hydrogen-oxygen gas mixture inhalation therapy in preventing DCI or CVS and improving outcomes in aSAH patients. Notably, this is the first large-scale trial of hydrogen therapy in aSAH patients. Given that the Chinese population represents a significant portion of the global population and the increasing incidence of stroke due to aging, optimizing patient care is vital. Given the current challenges in aSAH patient outcomes, initiating more prospective clinical trials is essential. Recent research has shown hydrogen's therapeutic potential, aligning with EBI in aSAH, driving our exploration of hydrogen therapy's mechanisms in post-aneurysm rupture damage.

ETHICS AND DISSEMINATION

The protocol for the HOMA study was approved by the Ethics Committee of Beijing Tiantan Hospital, Capital Medical University (KY 2022-020-02). All results of the present study will be published in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05282836. Registered on March 16, 2022.

The association between hemoglobin concentration and clinical outcomes after aneurysmal subarachnoid hemorrhage: Insights from the LongTEAM registry

OBJECTIVE

The aim of this study is to explore whether preoperative hemoglobin levels could serve as a prospective biomarker for early brain injury in patients with aneurysmal subarachnoid hemorrhage (aSAH). This investigation seeks to discern its association with postoperative complications and unfavorable clinical outcomes.

METHODS

We conducted a comprehensive analysis of data derived from the LongTeam registry, including patients with aSAH diagnosed between January 2015 and September 2021. These patients were stratified into three distinct groups based on their hemoglobin levels: anemic, standard, and elevated HGB. We employed logistic models featuring spline transformations to assess the relationship between HGB levels and in-hospital complications. Furthermore, a multivariate Cox proportional hazard model was employed to estimate the impact of elevated hemoglobin levels on the hazard function, which was elucidated through Kaplan-Meier curves.

RESULTS

Our study comprised a total of 988 patients, among whom 115 (11.6%) presented preoperative anemia, and 63 (6.4%) exhibited elevated preoperative HGB levels. Following adjustments for potential confounding factors, no significant disparity in risk was evident between anemic patients and those with standard HGB levels. However, individuals with elevated HGB levels displayed a heightened incidence and an increased risk of developing deep vein thrombosis (DVT, odds ratio [OR] = 2.39, 95% confidence interval [CI] = 1.16-4.91, p = 0.018; hazard ratio [HR] = 2.05, 95% CI 1.08-3.92, p = 0.015). Aberrant HGB concentrations did not demonstrate an association with other clinical outcomes.

CONCLUSION

Our findings emphasize that abnormal HGB levels show no association with adverse outcomes at the 90 days mark after accounting for clinical confounding factors in patients with aSAH. Simultaneously, the study illuminates the potential of HGB as an early indicator for identifying patients at a heightened risk of developing DVT.

A 90-Day Prognostic Model Based on the Early Brain Injury Indicators after Aneurysmal Subarachnoid Hemorrhage: the TAPS Score

This study aimed to establish a new scoring model based on the early brain injury (EBI) indicators to predict the 90-day functional outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). We retrospectively enrolled 825 patients and prospectively enrolled 108 patients with aSAH who underwent surgical clipping or endovascular coiling (derivation cohort = 640; validation cohort = 185; prospective cohort = 108) in our institute. We established a logistic regression model based on independent risk factors associated with 90-day unfavorable outcomes. The discrimination of the prognostic model was assessed by the area under the curve in a receiver operating characteristic curve analysis. The Hosmer-Lemeshow goodness-of-fit test and a calibration plot were used to evaluate the calibration of the prediction model. The developed scoring model named "TAPS" (total score, 0-7 points) included the following admission variables: age > 55 years old, WFNS grade of 4-5, mFS grade of 3-4, Graeb score of 5-12, white blood cell count > 11.28 × 10⁹/L, and surgical clipping. The model showed good discrimination with the area under the curve in the derivation, validation, and prospective cohorts which were 0.816 (p < 0.001, 95%CI = 0.77-0.86), 0.810 (p < 0.001, 95%CI = 0.73-0.90), and 0.803 (p < 0.001, 95%CI = 0.70-0.91), respectively. The model also demonstrated good calibration (Hosmer-Lemeshow goodness-of-fit test: X² = 1.75, df = 8, p = 0.988). Compared with other predictive models, TAPS is an easy handle tool for predicting the 90-day unfavorable outcomes of aSAH patients, which can help clinicians better understand the concept of EBI and quickly identify those patients at risk of poor prognosis, providing more positive treatment strategies. Trial registration: NCT04785976. Registered 5 March 2021-retrospectively registered, http://www.clinicaltrials.gov .

A Pooled Analysis of Preoperative Inflammatory Biomarkers to Predict 90-Day Outcomes in Patients with an Aneurysmal Subarachnoid Hemorrhage: A Single-Center Retrospective Study

An inflammatory response after an aneurysmal subarachnoid hemorrhage (aSAH) has always been in the spotlight. However, few studies have compared the prognostic impact of inflammatory biomarkers. Moreover, why these inflammatory biomarkers contribute to a poor prognosis is also unclear. We retrospectively reviewed aSAH patients admitted to our institution between January 2015 and December 2020. The 90-day unfavorable functional outcome was defined as a modified Rankin scale (mRS) of ≥ 3. Independent inflammatory biomarker-related risk factors associated with 90-day unfavorable outcomes were derived from a forward stepwise multivariate analysis. Receiver operating characteristic curve analysis was conducted to identify the best cut-off value of inflammatory biomarkers. Then, patients were divided into two groups according to each biomarker's cut-off value. To eliminate the imbalances in baseline characteristics, propensity score matching (PSM) was carried out to assess the impact of each biomarker on in-hospital complications. A total of 543 patients were enrolled in this study and 96 (17.7%) patients had unfavorable 90-day outcomes. A multivariate analysis showed that the white blood cell (WBC) count, the systemic inflammation response index, the neutrophil count, the neutrophil-to-albumin ratio, the monocyte count, and the monocyte-to-lymphocyte ratio were independently associated with 90-day unfavorable outcomes. The WBC count showed the best predictive ability (area under the curve (AUC) = 0.710, 95% CI = 0.652-0.769, p < 0.001). After PSM, almost all abnormal levels of inflammatory biomarkers were associated with a higher incidence of pneumonia during hospitalization. The WBC count had the strongest association with poor outcomes. Similar to nearly all other inflammatory biomarkers, the cause of poor prognosis may be the higher incidence of in-hospital pneumonia.

Predictive Values of White Blood Cell Count in Peripheral Blood at Admission on In-Hospital Complications and 90-Day Outcomes of Patients with Aneurysmal Subarachnoid Hemorrhage: Insights from the LongTEAM Registry

PURPOSE

This study aimed to explore the relationship between white blood cells (WBCs) at admission and clinical outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH).

PATIENTS AND METHODS

We analyzed data from patients with aSAH between January 2015 and September 2021 who were included in the LongTEAM (Long-term Prognosis of Emergency Aneurysmal Subarachnoid Hemorrhage) registry study. WBC is classified into four groups according to the quartile. We used the logistic model for in-hospital complications, mortality, modified Rankin scale (mRS) at discharge and 90 days to examine the relationship between WBC and clinical outcomes. We used WBC levels near odds ratio (OR) = 1 (Q1) in restricted cubic splines as the reference to evaluate whether there is a nonlinear relationship between WBC and clinical outcomes. Another Kaplan-Meier method was used to analyze the relationship between WBC levels and the risk of developing pneumonia.

RESULTS

Of the 988 patients included, the results showed that compared with patients in the Q1 group, patients in the highest quartile (Q4) had an increased incidence of 90-day unfavorable outcomes after adjusting the confounders (adjusted OR = 1.81, 95% CI = 1.02-3.20, p = 0.042), which may be caused by the increased incidence and risk of pneumonia (adjusted OR = 2.06, 95% CI = 1.30-3.29, p = 0.002; adjusted hazard ratio [HR]=1.63, 95% CI = 1.13-2.36, p < 0.001). The restricted cubic spline indicated that the incidence of developing pneumonia and 90-day unfavorable outcomes rises with increasing WBC levels (p for nonlinear = 0.135 and 0.113).

CONCLUSION

Patients with higher WBC at admission were associated with an increased incidence of 90-day unfavorable outcomes, which might be related to pneumonia.

Aneurysmal Subarachnoid Hemorrhage: an Overview of Inflammation-Induced Cellular Changes

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating disease that leads to poor neurological outcomes and is characterized by both vascular and neural pathologies. Recent evidence demonstrates that inflammation mediates many of the vascular and neural changes observed after SAH. Although most studies focus on inflammatory mediators such as cytokines, the ultimate effectors of inflammation in SAH are parenchymal brain and peripheral immune cells. As such, the present review will summarize our current understanding of the cellular changes of both CNS parenchymal and peripheral immune cells after SAH.

Carnosic Acid Mitigates Early Brain Injury After Subarachnoid Hemorrhage: Possible Involvement of the SIRT1/p66shc Signaling Pathway

Carnosic acid (CA) has been reported to exhibit a variety of bioactivities including antioxidation, neuroprotection, and anti-inflammation; however, the impact of CA on subarachnoid hemorrhage (SAH) has never been elucidated. The current study was undertaken to explore the role of CA in early brain injury (EBI) secondary to SAH and the underlying mechanisms. Adult male Sprague-Dawley rats were perforated to mimic a clinical aneurysm with SAH. CA or vehicle was administered intravenously immediately after the SAH occurred. Mortality, SAH grade, neurologic function scores, brain water content, Evans blue extravasation, and the levels of reactive oxygen species (ROS) levels in the ipsilateral cortex were determined 24 h after the SAH occurred. Western blot, immunofluorescence, Fluoro-Jade C (FJC) and TUNEL staining were also performed. Our results showed that CA decreased ROS levels, alleviated brain edema and blood-brain barrier permeability, reduced neuronal cell death, and promoted neurologic function improvement. To probe into the potential mechanisms. We showed that CA increased SIRT1, MnSOD, and Bcl-2 expression, as well as decreased p66shc, Bax, and cleaved caspase-3 expression. Interestingly, sirtinol, a selective inhibitor of SIRT1, abolished the anti-apoptotic effects of CA. Taken together, these data revealed that CA has a neuroprotective role in EBI secondary to SAH. The potential mechanism may involve suppression of neuronal apoptosis through the SIRT1/p66shc signaling pathway. CA may provide a promising therapeutic regimen for management of SAH.

Fluoxetine-enhanced autophagy ameliorates early brain injury via inhibition of NLRP3 inflammasome activation following subrachnoid hemorrhage in rats

Background

The NLRP3 inflammasome is a multiprotein complex that regulates the innate immune inflammatory response by activating caspase-1 and subsequent IL-1β and IL-18. Fluoxetine has been shown to have the anti-inflammatory properties in many disease models. However, the effects and mechanisms of these effects of fluoxetine in early brain injury after subarachnoid hemorrhage (SAH) have not been defined.

Methods

The SAH model was induced by an endovascular perforation in adult male Sprague-Dawley (SD) rats weighing 300–320 g. N-Ac-Tyr-Val-Ala-Asp-chloromethyl ketone (AC-YVAD-CMK) was injected intraperitoneally (5 mg/kg) 1 h after SAH. Fluoxetine was administered via intravenous route 6 h after SAH. 3-Methyladenine (3-MA) was intracerebroventricularly injected 20 min before SAH. SAH grade, neurological function, brain water content, propidium iodide (PI) staining, western blot, double immunostaining, and transmission electron microscopy were performed.

Results

Expression of caspase-1 increased and peaked at 24 h after SAH. Caspase activation was along with the increased necrotic cells, which occurred mainly in neurons. Necrotic cell death of microglia and astrocyte were also found. Administration of AC-YVAD-CMK, a caspase-1 inhibitor, reduced the expression of IL-1β and IL-18 and the number of PI-positive cells, attenuated brain edema, and improved neurological function, which was also observed in fluoxetine-treated rats. Furthermore, fluoxetine treatment significantly decreased the expression of NLRP3 and cleaved caspase-1 and upregulated the expression of beclin-1, a marker for autophagy. Finally, the effects of fluoxetine in NLRP3 inflammasome activation were reversed by additional 3-MA administration.

Conclusions

Together, our present study indicated that NLRP3 inflammasome and caspase-1 activation play a deleterious role in early brain injury and fluoxetine mitigates NLRP3 inflammasome and caspase-1 activation through autophagy activation after SAH, providing a potential therapeutic agent for SAH treatment.

Electronic supplementary material

The online version of this article (10.1186/s12974-017-0959-6) contains supplementary material, which is available to authorized users.