Sex-Related Differences in Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage

Development of a 3D Brain Model to Study Sex-Specific Neuroinflammation After Hemorrhagic Stroke

Subarachnoid hemorrhage (SAH) accounts for 5% of stroke, with women having a decreased inflammatory response compared to men; however, this mechanism has yet to be identified. One hurdle in SAH research is the lack of human brain models. Studies in murine models are helpful, but human models should be used in conjunction for improved translatability. These observations lead us to develop a 3D system to study the sex-specific microglial and neuroglial function in a novel in vitro human SAH model and compare it to our validated in vivo SAH model. Our lab has developed a 3D, membrane-based in vitro cell culture system with human astrocytes, microglia, and neurons from both sexes. The 3D cultures were incubated with male and female cerebrospinal fluid from SAH patients in the Neuro-ICU. Furthermore, microglial morphology, erythrophagocytosis, microglial inflammatory cytokine production, and neuronal apoptosis were studied and compared with our murine SAH models. The human 3D system demonstrated intercellular interactions and proportions of the three cell types similar to the adult human brain. In vitro and in vivo models of SAH showed concordance in male microglia being more inflammatory than females via morphology and flow cytometry. On the contrary, both in vitro and in vivo models revealed that female microglia were more phagocytic and less prone to damaging neurons than males. One possible explanation for the increased phagocytic ability of female microglia was the increased expression of CD206 and MerTK. Our in vitro, human, 3D cell culture SAH model showed similar results to our in vivo murine SAH model with respect to microglial morphology, inflammation, and phagocytosis when comparing the sexes. A human 3D brain model of SAH may be a useful adjunct to murine models to improve translation to SAH patients.

Macrophage Lyn Kinase Is a Sex-Specific Regulator of Post-Subarachnoid Hemorrhage Neuroinflammation

BACKGROUND

Lyn kinase is a member of the Src family of tyrosine kinases, primarily known for its role in regulating immune cell signaling. It can phosphorylate and modulate the activity of various proteins involved in immune responses, including Toll-like receptor 4 (TLR4). TLR4-mediated inflammatory pathways have been extensively studied; however, the sex-specific interaction of TLR4 and Lyn in neuroinflammation after aneurysmal subarachnoid hemorrhage (SAH) has yet to be investigated. SAH occurs due to a ruptured aneurysm, and the consequences often lead to neuroinflammation and cognitive impairments. In our study, we investigated the sex-specific involvement of Lyn kinase in regulating TLR4 signaling to understand the TLR4-mediated inflammatory response after SAH.

METHODS

Cell-specific Lyn knockout mice of both sexes were used for this study. Wild-type and conditional knockout mouse brains were analyzed by multicolor flow cytometry, immunohistochemistry, and western blotting at postoperative day 7 following SAH surgery. An unbiased spatial transcriptomic analysis was performed with the frozen mouse brain tissues. A 3-dimensional brain stroke model and cerebrospinal fluid samples of patients with SAH were also used for this study.

RESULTS

Our overall animal and patient data from flow cytometry, immunohistochemistry, western blot, cognitive function tests, and spatial transcriptomic data revealed that Lyn kinase is a sex-specific regulator in inflammatory cytokine production, red blood cell phagocytosis, neuronal apoptosis, and cognitive function, as well as a negative regulator of TLR4 signaling pathways.

CONCLUSIONS

Our results highlight sex-specific modulation of Lyn kinase activity in TLR4 signaling after hemorrhagic stroke and indicate that successful treatment of neuroinflammation may require sex-specific treatments.

A National Cohort with Aneurysmal Subarachnoid Hemorrhage-Patient Characteristics, Choice of Treatment, Clinical Outcome, and Factors of Prognostic Importance

OBJECTIVE

To study associations of clinical characteristics and treatment choice with functional outcome, mortality, and time to death in a national sample of aneurysmal subarachnoidal hemorrhage patients.

METHODS

Data were extracted from a prospective nationwide multicenter study performed in September 2014 to March 2018. Glasgow Outcome Scale Extended (GOSE) grade, 1-year mortality, and survival probability were assessed at one year after ictus. Logistic univariate, multivariate, and Cox regression analyses were used to study the variables' associations with the outcomes.

RESULTS

Unfavorable dichotomized GOSE (dGOSE; grades 1-4) was observed in 35.4% of patients. Microsurgery was preferred for middle cerebral artery aneurysms and Fisher grade 4. Treatment modality was not associated with any outcome measure. Dichotomized World Federation of Neurosurgical Societies (dWFNS), age, and delayed ischemic neurological deficit (DIND) showed significant correlations with dGOSE and 1-year mortality in multivariate regression analyses. Pupil dilatation was associated with a 1-year mortality outcome. Cox regression analysis showed lower survival probability for pupil dilatation (hazard ratio [HR]: 3.546), poor dWFNS (HR: 3.688), higher age (HR: 1.051), and DIND occurrence (HR: 2.214).

CONCLUSIONS

The patient selection in Sweden after aneurysmal subarachnoidal hemorrhage showed similar values for dGOSE, 1-year mortality, and survival probability between patients treated with microsurgery or endovascular technique. Poor dWFNS, higher age, and DIND were significantly associated with unfavorable dGOSE, mortality, and survival probability. Pupil dilatation was significantly associated with mortality and survival probability.

The urotensin II receptor triggers an early meningeal response and a delayed macrophage-dependent vasospasm after subarachnoid hemorrhage in male mice

Subarachnoid hemorrhage (SAH) can be associated with neurological deficits and has profound consequences for mortality and morbidity. Cerebral vasospasm (CVS) and delayed cerebral ischemia affect neurological outcomes in SAH patients, but their mechanisms are not fully understood, and effective treatments are limited. Here, we report that urotensin II receptor UT plays a pivotal role in both early events and delayed mechanisms following SAH in male mice. Few days post-SAH, UT expression is triggered by blood or hemoglobin in the leptomeningeal compartment. UT contributes to perimeningeal glia limitans astrocyte reactivity, microvascular alterations and neuroinflammation independent of CNS-associated macrophages (CAMs). Later, CAM-dependent vascular inflammation and subsequent CVS develop, leading to cognitive dysfunction. In an SAH model using humanized UTh+/h+ male mice, we show that post-SAH CVS and behavioral deficits, mediated by UT through Gq/PLC/Ca2+ signaling, are prevented by UT antagonists. These results highlight the potential of targeting UT pathways to reduce early meningeal response and delayed cerebral ischemia in SAH patients.

Sex-Related Differences in Mortality, Delayed Cerebral Ischemia, and Functional Outcomes in Patients with Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

Background/Objective: Sex-related differences among patients with aneurysmal subarachnoid hemorrhage (aSAH) and their potential clinical implications have been insufficiently investigated. To address this knowledge gap, we conduct a comprehensive systematic review and meta-analysis. Methods: Sex-specific differences in patients with aSAH, including mortality, delayed cerebral ischemia (DCI), and functional outcomes were assessed. The functional outcome was dichotomized into favorable or unfavorable based on the modified Rankin Scale (mRS), Glasgow Outcome Scale (GOS), and Glasgow Outcome Scale Extended (GOSE). Results: Overall, 2823 studies were identified in EMBASE, MEDLINE, PubMed, and by manual search on 14 February 2024. After an initial assessment, 74 studies were included in the meta-analysis. In the analysis of mortality, including 18,534 aSAH patients, no statistically significant differences could be detected (risk ratio (RR) 0.99; 95% CI, 0.90-1.09; p = 0.91). In contrast, the risk analysis for DCI, including 23,864 aSAH patients, showed an 11% relative risk reduction in DCI in males versus females (RR, 0.89; 95% CI, 0.81-0.97; p = 0.01). The functional outcome analysis (favorable vs. unfavorable), including 7739 aSAH patients, showed a tendency towards better functional outcomes in men than women; however, this did not reach statistical significance (RR, 1.02; 95% CI, 0.98-1.07; p = 0.34). Conclusions: In conclusion, the available data suggest that sex/gender may play a significant role in the risk of DCI in patients with aSAH, emphasizing the need for sex-specific management strategies.

Comparison of sex differences on outcomes after aneurysmal subarachnoid hemorrhage: a propensity score-matched analysis

OBJECTIVE

Sex differences in outcomes of patients with aneurysmal subarachnoid hemorrhage (aSAH) remain controversial. Therefore, the aim of this study was to investigate the sex differences in the prognosis of patients with aSAH.

METHODS

This study retrospectively analyzed the clinical data of aSAH patients admitted to the Department of Neurosurgery of General Hospital of Northern Theater Command, from April 2020 to January 2022. The modified Rankin Scale (mRS) was used to evaluate outcomes at 3-month post-discharge. Baseline characteristics, in-hospital complications and outcomes were compared after 1:1 propensity score matching (PSM).

RESULTS

A total of 665 patients were included and the majority (63.8%) were female. Female patients were significantly older than male patients (59.3 ± 10.9 years vs. 55.1 ± 10.9 years, P < 0.001). After PSM, 141 male and 141 female patients were compared. Comparing postoperative complications and mRS scores, the incidence of delayed cerebral ischemia (DCI) and hydrocephalus and mRS ≥ 2 at 3-month were significantly higher in female patients than in male patients. After adjustment, the analysis of risk factors for unfavorable prognosis at 3-month showed that age, sex, smoking, high Hunt Hess grade, high mFisher score, DCI, and hydrocephalus were independent risk factors.

CONCLUSION

Female patients with aSAH have a worse prognosis than male patients, and this difference may be because females are more vulnerable to DCI and hydrocephalus.

Sex Differences in Case Fatality of Aneurysmal Subarachnoid Hemorrhage: A Systematic Review

INTRODUCTION

Aneurysmal subarachnoid hemorrhage (SAH) is more common in women than in men, contrary to most cardiovascular diseases. However, it is unclear whether the case fatality rate (CFR) of SAH also differs by sex. Thus, we performed a systematic review to address the relationship between sex and SAH CFRs.

METHODS

We conducted a systematic literature search in PubMed, Scopus, and Cochrane library databases. We focused on population-based studies that included both nonhospitalized and hospitalized SAHs and had either reported 1-month (28-31 day) SAH CFRs separately for men and women or calculated risk estimates for SAH CFR by sex. For quality classification, we used the Cochrane Collaboration Handbook and Critical Appraisal Skills Program guidelines. We pooled the study cohorts and calculated relative risk ratios (RRs) with 95% confidence intervals (CIs) for SAH death between women and men using a random-effects meta-analysis model.

RESULTS

The literature search yielded 5,592 initial publications, of which 33 study cohorts were included in the final review. Of the 33 study cohorts, only three reported significant sex differences, although the findings were contradictory. In the pooled analysis of all 53,141 SAH cases (60.3% women) from 26 countries, the 1-month CFR did not differ (RR = 0.99 [95% CI: 0.93-1.05]) between women (35.5%) and men (35.0%). According to our risk-of-bias evaluation, all 33 study cohorts were categorized as low quality. The most important sources of bias risks were related to the absence of proper confounding control (all 33 study cohorts), insufficient sample size (27 of 33 study cohorts), and poor/unclear diagnostic accuracy (27 of 33 study cohorts).

CONCLUSION

Contrary to SAH incidence rates, the SAH CFRs do not seem to differ between men and women. However, since none of the studies were specifically designed to examine the sex differences in SAH CFRs, future studies on the topic are warranted.

Sex and hypertensive organ damage: stroke

Stroke is a common cause of death and disability in both men and women. Differences in the incidence, presenting features and outcome after stroke have been reported between men and women. The global lifetime risk of stroke of approximately 25% is similar in men and women, although in women, the first cardiovascular event is more likely to be stroke than in men. Concerningly, there are reports of underuse of some treatments in women, although these differences may be diminishing over time. In addition, there are specific clinical challenges that can arise in women with stroke, such as stroke in people taking hormonal therapy, and stroke during pregnancy and stroke in the post-partum period. This review will cover these areas highlighting important differences and areas for future research. We found there are important differences in incidence of stroke, which differ by age. Further, there is concerning evidence that some treatments such as intravenous thrombolysis are underused in women. While there may be some differences in the relative effectiveness of treatments such as antiplatelet therapy and blood pressure reduction between men and women, for most aspects of stroke care, benefit is clear in both men and women and the emphasis must be on more equitable access. There is limited evidence to inform decision making during pregnancy and the post-partum period, but guidelines now exist and further research is needed in these areas.

Sex-related differences in postoperative complications following elective craniotomy for intracranial lesions: An observational study

INTRODUCTION

The integration of sex-related differences in neurosurgery is crucial for new, possible sex-specific, therapeutic approaches. In neurosurgical emergencies, such as traumatic brain injury and aneurysmal subarachnoid hemorrhage, these differences have been investigated. So far, little is known concerning the impact of sex on frequency of postoperative complications after elective craniotomy. This study investigates whether sex-related differences exist in frequency of postoperative complications in patients who underwent elective craniotomy for intracranial lesion.

MATERIAL AND METHODS

All consecutive patients who underwent an elective intracranial procedure over a 2-year period at our center were eligible for inclusion in this retrospective study. Demographic data, comorbidities, frequency of postoperative complications at 24 hours following surgery and at discharge, and hospital length of stay were compared among females and males.

RESULTS

Overall, 664 patients were considered for the analysis. Of those, 339 (50.2%) were females. Demographic data were comparable among females and males. More females than males suffered from allergic, muscular, and rheumatic disorders. No differences in frequency of postoperative complications at 24 hours after surgery and at discharge were observed among females and males. Similarly, the hospital length of stay was comparable.

CONCLUSIONS

In the present study, no sex-related differences in frequency of early postoperative complications and at discharge following elective craniotomy for intracranial lesions were observed.

Comparison of Sex Differences in Outcomes of Patients With Aneurysmal Subarachnoid Hemorrhage: A Single-Center Retrospective Study

BACKGROUND

Sex differences in the outcomes of patients with aneurysmal subarachnoid hemorrhage (aSAH) remain controversial. The aim of this study was to evaluate sex differences in the outcomes of patients with aSAH.

METHOD

This study retrospectively analyzed the clinical data of consecutive patients with aSAH, admitted to the Department of Neurosurgery, Wuhan University Zhongnan Hospital, from May 1, 2020 to December 31, 2020. The modified Rankin Scale (mRS) score was used to evaluate the prognosis of patients at discharge. Outcome indicators included cerebral ischemia, hydrocephalus, and mRS ≥ 2 at discharge.

RESULTS

The majority (65%) of the 287 patients with aSAH included in the study were females. Patients were divided into female (n = 184) and male (n = 99) groups; the female patients were significantly older than the male patients (61.3 ± 8.5 years vs. 60.0 ± 8.5 years, p = 0.032). The incidence of comorbidities (hypertension, diabetes, and heart disease) was higher in the female group than in the male group, but the difference was not statistically significant. Although more female patients than male patients underwent endovascular treatment, there was no statistical difference in the treatment approach between the two groups. Comparison of post-operative complications and mRS scores at discharge revealed that the rate of cerebral ischemia and mRS ≥ 2 at discharge were significantly higher among female patients than among male patients. Moreover, this difference persisted after propensity adjustment for age and treatment approach. Analysis of risk factors for poor prognosis at discharge in both pre- and post-adjustment patients revealed cerebral ischemia and high mFisher score (mFisher = 3/4) to be independent risk factors.

CONCLUSION

Female patients with aSAH have a worse prognosis than male patients, and this difference may be because women are more susceptible to cerebral ischemia.

Unfavorable Outcome After Good Grade Aneurysmal Subarachnoid Hemorrhage: Exploratory Analysis

OBJECTIVE

Patients with good-grade aneurysmal subarachnoid hemorrhage (aSAH) are thought to recover well, yet some do not. This work sought to identify predictors of unfavorable functional outcome after good-grade aSAH.

METHODS

We performed a post-hoc analysis of the CONSCIOUS-1 trial. Patients with World Federation of Neurosurgical Societies grades I or II aSAH were included. The primary outcome was unfavorable functional outcome (defined as a modified Rankin Scale score >2) at 12 weeks. Parametric and nonparametric testing were used as appropriate. Variables were classified as modifiable or nonmodifiable, depending on whether they were present at patient admission. Stepwise logistic regression models were created for modifiable and nonmodifiable predictors of outcome. Independent predictors in the respective multivariate analyses were combined into a final multivariate regression model.

RESULTS

We included 301 patients, 67 of whom (22%) had an unfavorable outcome. Of the nonmodifiable predictors, higher admission systolic blood pressure (P = 0.002) and female sex (P = 0.011) were independently associated with unfavorable outcome. Potentially modifiable independent predictors of outcome were delayed cerebral ischemia (P = 0.039), higher maximum temperature (0.036), suffering a respiratory system complication (P = 0.004), and suffering an intracranial hemorrhagic complication (P = 0.022). All variables found to be independently predictive of poor outcome in their respective models retained statistical significance in the combined multivariate analysis.

CONCLUSIONS

About 1 in 5 good-grade aSAH patients enrolled in CONSCIOUS-1 suffered an unfavorable functional outcome. Admission systolic blood pressure, female sex, hyperthermia, delayed cerebral ischemia, respiratory complications, and intracranial hemorrhagic complications may be predictive of outcome.

Sex differences in aneurysmal subarachnoid haemorrhage (aSAH): aneurysm characteristics, neurological complications, and outcome

BACKGROUND

Women are over-represented in aSAH cohorts, but whether their outcomes differ to men remains unclear. We examined if sex differences in neurological complications and aneurysm characteristics contributed to aSAH outcomes.

METHODS

In a retrospective cohort (2010-2016) of all aSAH cases across two hospital networks in Australia, information on severity, aneurysm characteristics and neurological complications (rebleed before/after treatment, postoperative stroke < 48 h, neurological infections, hydrocephalus, seizures, delayed cerebral ischemia [DCI], cerebral infarction) were extracted. We estimated sex differences in (1) complications and aneurysm characteristics using chi square/t-tests and (2) outcome at discharge (home, rehabilitation or death) using multinomial regression with and without propensity score matching on prestroke confounders.

RESULTS

Among 577 cases (69% women, 84% treated) aneurysm size was greater in men than women and DCI more common in women than men. In unadjusted log multinomial regression, women had marginally greater discharge to rehabilitation (RRR 1.15 95% CI 0.90-1.48) and similar likelihood of in-hospital death (RRR 1.02 95% CI 0.76-1.36) versus discharge home. Prestroke confounders (age, hypertension, smoking status) explained greater risk of death in women (rehabilitation RRR 1.13 95% CI 0.87-1.48; death RRR 0.75 95% CI 0.51-1.10). Neurological complications (DCI and hydrocephalus) were covariates explaining some of the greater risk for poor outcomes in women (rehabilitation RRR 0.87 95% CI 0.69-1.11; death RRR 0.80 95% CI 0.52-1.23). Results were consistent in propensity score matched models.

CONCLUSION

The marginally poorer outcome in women at discharge was partially attributable to prestroke confounders and complications. Improvements in managing complications could improve outcomes.

Sex differences in stroke

Sex disparities within the field of stroke, including subarachnoid hemorrhages (SAHs), have been in focus during the last 2 decades. It is clear that stroke incidence is higher in men, and also that men have their first stroke earlier than women. On the other hand, women have more severe strokes, mainly because cardioembolic strokes are more common in women. This leads to higher case fatality and worse functional outcome in women. It has often been pointed out that women more often have nontraditional stroke symptoms, and therefore may seek medical help later. After discharge from the hospital, female stroke survivors live alone in many cases and are dependent on external care. Therefore, these women frequently rate their quality of life (QoL) lower than men do. Female spouses more often provide help to their male stroke survivors than the reverse, and they accept a heavier burden. These caregivers are at high risk for depression, low QoL, and low psychologic wellbeing. SAH is a special form of stroke, often caused by a ruptured aneurysm. It is about 20% more common in women. The case fatality is high, but does not differ between the sexes.

The Factors Associated with Outcomes in Surgically Managed Ruptured Cerebral Aneurysm

Background

Ruptured cerebral aneurysm is a life-threatening condition that requires urgent medical attention. In Malaysia, a prospective study by the Umum Sarawak Hospital, Neurosurgical Center, in the year 2000-2002 revealed an average of two cases of intracranial aneurysms per month with an operative mortality of 20% and management mortality of 25%. Failure to diagnose, delay in admission to a neurosurgical centre, and lack of facilities could have led to the poor surgical outcome in these patients. The purpose of this study is to identify the factors that significantly predict the outcome of patients undergoing a surgical clipping of ruptured aneurysm in the local population.

Material and Method

A single center retrospective study with a review of medical records was performed involving 105 patients, who were surgically treated for ruptured intracranial aneurysms in the Sultanah Aminah Hospital, in Johor Bahru, from July 2011 to January 2016. Information collected was the patient demographic data, Glasgow Coma Scale (GCS) prior to surgery, World Federation of Neurosurgical Societies Scale (WFNS), subarachnoid hemorrhage (SAH) grading system, and timing between SAH ictus and surgery. A good clinical grade was defined as WFNS grade I-III, whereas, WFNS grades IV and V were considered to be poor grades. The outcomes at discharge and six months post surgery were assessed using the modified Rankin's Scale (mRS). The mRS scores of 0 to 2 were grouped into the "favourable" category and mRS scores of 3 to 6 were grouped into the "unfavourable" category. Only cases of proven ruptured aneurysmal SAH involving anterior circulation that underwent surgical clipping were included in the study. The data collected was analysed using the Statistical Package for Social Sciences (SPSS). Univariate and multivariate analyses were performed and a P-value of < 0.05 was considered to be statistically significant.

Result

A total of 105 patients were included. The group was comprised of 42.9% male and 57.1% female patients. The mean GCS of the patients subjected to surgical clipping was 13, with the majority falling into the good clinical grade (78.1%). The mean timing of the surgery after SAH was 5.3 days and this was further categorised into early (day one to day three, 45.3%), intermediate (day four to day ten, 56.2%), and late (after day ten, 9.5%). The total favourable outcome achieved at discharge was 59.0% as compared to 41.0% of the unfavourable outcome, with an overall mortality rate of 10.5%. At the six-month post surgery review (n = 94), the patients with a favourable outcome constituted 71.3% as compared to 28.7% with an unfavourable outcome. The mortality, six months post surgery was 3.2%. On a univariate analysis of early surgical clipping, patients with a better GCS and good clinical grade had a significantly better outcome at discharge. Based on the univariate study, six months post surgery, the timing of the surgery and the clinical grade remained significant predictors of the outcome. On the basis of the multivariate analysis, male patients of younger age, with a good clinical grade, were associated with favourable outcomes, both at discharge and six months post surgery.

Conclusion

In this study, we concluded that younger male patients with a good clinical grade were associated with a favourable outcome both at discharge and six months post surgery. We did not find the timing of the surgery, size of the aneurysm or duration of surgery to be associated with a patient's surgical outcome. Increasing age was not associated with the surgical outcome in a longer term of patient's follow up.

Rupture of a non-traumatic anterior communicating artery aneurysm: Does location of aneurysm associate with functional independence following post-acute in-patient neurorehabilitation?

OBJECTIVE

Patients with non-traumatic rupture of an aneurysm located at the anterior communicating artery (ACoA) often experience cognitive disabilities. It is unknown whether location of aneurysm also affects the possibility for improvement in functional independence compared to patients with an aneurysmal subarachnoid hemorrhage (a-SAH) located elsewhere. The aim was to explore the association between location of aneurysm (ACoA versus other) and level of functional independence, measured by Functional Independence Measure (FIM), at discharge from rehabilitation. Additionally, age and FIM at admission were explored.

METHOD

Historical cohort study among 107 patients with a-SAH based on data from a clinical database and a population-based register. Data were analyzed using multivariable logistic regression.

RESULTS

Patients with ACoA were admitted with poorer cognitive FIM (median 6 (IQR 5-14) compared to patients with aneurysms located elsewhere (median 12 (IQR 6-23) (p = 0.0129); no difference at discharge. No association between aneurysm location and functional independence was observed. Higher age was associated with poorer outcome in bowel management OR 0.54 (95% CI 0.31-0.92), bladder management OR 0.59 (95% CI 0.35-0.98), comprehension OR 0.53 (95% CI 0.30-0.94), and memory OR 0.48 (95% CI 0.25-0.93). Overall, FIM at admission was associated with functional independence at discharge with the exception of stair walking and bladder management which did not reach statistical significance.

CONCLUSION

ACoA was not associated with poorer level of functional independence compared to patients with a-SAH located elsewhere. Higher age was associated with poorer outcome in continence, comprehension, and memory, whereas higher FIM was associated with better functional independence across items at discharge.