Relationship between Postmenopausal Estrogen Deficiency and Aneurysmal Subarachnoid Hemorrhage

Subarachnoid haemorrhage and intracranial aneurysms in Greenland in the period 2018-2021: incidence, outcome and familial disposition

Subarachnoid haemorrhages (SAH) caused by rupture of intracranial aneurysms (IA) are a severe condition. Earlier studies found a higher incidence of SAH in Greenlandic patients compared to Danish patients, with familial aggregation also higher in Greenland. However, updated data is lacking. To investigate the contemporary incidence, outcome, and familial disposition of SAH/IA in Greenlandic patients in 2018-2021. Greenlandic patients diagnosed with ruptured or unruptured IA (UIA) during 2018-2021 were included. Data was obtained from patient files, x-ray department, and discharge registry. Incidence rates were estimated as cases/100,000/year. Direct age-standardised incidence rates were calculated using WHO 2000-2025 as standards. Of 30 SAH patients, 20 (66.7%) were females, 10 (33.3%) males. Of 36 UIA patients, 27 (75.0%) were females, 9 (25.0%) males. For SAH, crude incidence was 13.4/100,000/year, age-standardised incidence was 10.8/100,000/year. Familial history was observed in 30.0% of SAH patients. 5 patients (16.7%) died before treatment, 28-day case-fatality rate (CFR) for all patients was 23.3%. Overall and age-standardised incidence rates were similar to previous studies but higher among females and compared to neighbouring countries. A high occurrence of familial history was reported. SAH remains a serious condition in Greenland, as evidenced by five fatalities before treatment was administered.

Hormone Concentration Measurement in Intracranial Dural Arteriovenous Fistulae

OBJECTIVE

Intracranial dural arteriovenous fistulae (DAVFs) represent a subset of cerebral vascular malformations associated with significant morbidity and mortality. In Japan, DAVF exhibits sex-based differences in anatomical distribution, with female predominance in the cavernous sinus (CS) and male predominance in the transverse sinus (TS). Nevertheless, the pathophysiology of DAVF is not fully understood, and hormonal influences are hypothesized to play a role in its development. This study aimed to investigate changes in the concentrations of sex steroid hormones between intracranial and peripheral sampling sites in patients with CS- and TS-DAVF.

METHODS

We recruited 19 patients with CS-DAVF (n = 12) and TS-DAVF (n = 7) in this study. Blood hormone measurements were obtained from peripheral and jugular bulb samples during endovascular intervention. Hormone concentrations were analyzed using enzyme-linked immunosorbent assay kits, and statistical analyses were performed.

RESULTS

Our study revealed a higher prevalence of CS-DAVF in females and TS-DAVF in males, which is consistent with previous studies. Estradiol concentration was significantly lower in the jugular bulb compared with in the periphery in both patients with CS- and TS-DAVF. This decrease in estradiol was observed irrespective of the patient's sex and independent of follicle-stimulating hormone levels.

CONCLUSIONS

These findings indicate a local decrease in estradiol levels within the intracranial vasculature of patients with DAVF. This suggests a potential multifactorial role of estradiol in the pathomechanism of DAVFs, warranting further investigation to understand its influence on DAVF formation and potential targeted therapies, thereby enhancing patient outcomes.

Exploring the potential of VGLL3 methylation as a prognostic indicator for intracranial aneurysm with gender-specific considerations

DNA methylation is widely recognized to play a role in intracranial aneurysm (IA) pathogenesis. We investigated the levels of methylation of vestigial-like 3 (VGLL3) in IA and explored its potential as a prognostic indicator. A total of 48 patients with IA and 48 healthy controls were included in the present study. Methylation levels of CpG sites were assessed using bisulfite pyrosequencing, and levels of VGLL3, TEAD, and YAP in the blood were measured by real-time quantitative polymerase chain reaction testing. VGLL3 methylation was significantly higher in controls than in IA patients (P=0.001), and this phenomenon was more pronounced in females (P<0.001). Compared with the control group, the expression levels of VGLL3 and TEAD in the blood of IA patients were significantly increased, while YAP was significantly decreased. VGLL3 methylation was positively correlated with HDL (P=0.003) and female Lpa concentration (r = 0.426, P=0.03), and was also negatively correlated with age (P=0.003), APOE (P=0.005), and VGLL3 mRNA expression (P<0.001). Methylation and mRNA expression of VGLL3 may serve as indicators of IA risk in females (AUC = 0.810 and 0.809). VGLL3 methylation may participate in the pathogenesis of IA by regulating the expression of the VGLL3/TEAD/YAP pathway, and its gene methylation and expression levels have IA risk prediction value.

Sex differences in patients with and without high-risk factors associated with aneurysmal subarachnoid hemorrhage

BACKGROUND

Controversy remains regarding the appropriate screening for intracranial aneurysms or for the treatment of aneurysmal subarachnoid hemorrhage (aSAH) for patients without known high-risk factors for rupture. This study aimed to assess how sex affects both aSAH presentation and outcomes for aSAH treatment.

METHOD

A retrospective cohort study was conducted of all patients treated at a single institution for an aSAH during a 12-year period (August 1, 2007-July 31, 2019). An analysis of women with and without high-risk factors was performed, including a propensity adjustment for a poor neurologic outcome (modified Rankin Scale [mRS] score > 2) at follow-up.

RESULTS

Data from 1014 patients were analyzed (69% [n = 703] women). Women were significantly older than men (mean ± SD, 56.6 ± 14.1 years vs 53.4 ± 14.2 years, p < 0.001). A significantly lower percentage of women than men had a history of tobacco use (36.6% [n = 257] vs 46% [n = 143], p = 0.005). A significantly higher percentage of women than men had no high-risk factors for aSAH (10% [n = 70] vs 5% [n = 16], p = 0.01). The percentage of women with an mRS score > 2 at the last follow-up was significantly lower among those without high-risk factors (34%, 24/70) versus those with high-risk factors (53%, 334/633) (p = 0.004). Subsequent propensity-adjusted analysis (adjusted for age, Hunt and Hess grade, and Fisher grade) found no statistically significant difference in the odds of a poor outcome for women with or without high-risk factors for aSAH (OR = 0.7, 95% CI = 0.4-1.2, p = 0.18).

CONCLUSIONS

A higher percentage of women versus men with aSAH had no known high-risk factors for rupture, supporting more aggressive screening and management of women with unruptured aneurysms.

Sex-related differences in symptom presentation of patients with aneurysmal subarachnoid hemorrhage

Background: In patients with myocardial infarction, atypical symptoms at onset have been demonstrated in women. We aimed to investigate the presence of sex-related differences in symptom presentation in patients with aneurysmal subarachnoid hemorrhage (aSAH) to enable earlier diagnosis and treatment. Methods: We assessed symptoms on admission to hospital in 343 patients with aSAH in this retrospective single-center cohort-study. Univariate statistical analysis was performed by comparing sexes including the whole study population and subgroups (dichotomized using Fisher scale 1-2 vs. 3-4, WFNS grade 1-3 vs. 4-5, and anterior vs. posterior circulation aneurysms, respectively). Results: The majority of patients was female (63.6%, n=218, vs. 36.4%, n=125), the mean age 57.4 years (standard deviation (SD) 13.3) with older women compared to men (59.2, SD 13.8, vs. 54.4, SD 11.6; p=0.003). Anterior communicating artery (AcomA) aneurysms were most common (30.9%, n=106), predominantly in men (43.2%, n=54, vs. 23.9%, n=52; p=0.0002), whereas posterior communicating artery (PcomA) aneurysms were more frequent in women (19.3%, n=42, vs. 8.8%, n=11; p=0.005). Exercise-induced headache was more often reported by men (10.4%, n=13, vs. 5%, n=11; p=0.04) in all patients as well as in the subgroup of WFNS 1-3. Anisocoria was more frequent in women within the subgroup of severely impaired consciousness (WFNS 4-5; 25.3%, n=22, vs. 10.7%, n=6; p=0.032). For all other symptoms, there was no evidence for sex-specific differences in the whole study group as well as in subgroups. Conclusion: Our results show no evidence for relevant sex-related differences in symptom presentation at onset in aSAH patients. Women presenting with an acute onset anisocoria should be screened even more carefully for an underlying ruptured Pcom aneurysm.

Integrated analysis identifies the IL6/JAK/STAT signaling pathway and the estrogen response pathway associated with the pathogenesis of intracranial aneurysms

Objective

We intended to identify the potential key biomarker and pathways that correlated with infiltrating immune cells during the pathogenesis of intracranial aneurysms (IA), to develop a diagnostic model, and to predict therapeutic drugs.

Methods

Three datasets containing intracranial aneurysm tissue samples and normal artery control samples from Gene Expression Omnibus (GEO) were included. Gene-set variation analysis(GSVA) and gene set enrichment analysis (GSEA) were conducted to find the significant differentially expressed pathways in IA formation. The least absolute shrinkage and selection operator (LASSO) regression and the multivariate logistic regression analysis were performed to identify the characteristic genes in the IL6/JAK/STAT signaling pathway (ISP) and the estrogen response pathway (ERP). A diagnostic model was constructed. xCell was used to identify immune cell types in IA pathogenesis. We used the weighted gene co-expression network analysis (WGCNA) algorithm to explore the correlations between the key modules and the four traits. Potential therapeutic drugs were investigated in Enrichr and Drugbank database.

Results

The ISP is significant positively correlated with IA onset. The biological function of the ISP is positively correlated with that of the ERP, and is significantly associated with immune cells activities. CSF2RB, FAS, IL6, PTPN1, STAT2, TGFB1 of the ISP gene set and ALDH3A2, COX6C, IGSF1, KRT18, MICB, NPY1R of the ERP gene set were proved to be the characteristic genes. The STAT2 gene can be the potential biomarker of IA onset. The immune score of IA samples was significantly higher than the controls. The STAT2 gene expression is associated with infiltration of immune cells. The WGCNA results were consistent with our finds. Acetaminophen can be a potential therapeutic drug for IA targeting STAT2.

Conclusions

We identified that the ISP was one of the most significant positively correlated pathways in IA onset, and it was activated in this process concordant with the ERP and immune responses. Except for beneficial effects, complex and multiple roles of estrogen may be involved in IA formation. STAT2 could be a potential biomarker and a promising therapeutic target of IA pathogenesis.

Association of Reproductive Life Span and Age at Menopause With the Risk of Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND OBJECTIVES

Subarachnoid hemorrhage from cerebral aneurysm remains a devastating disease with high mortality and morbidity. Cerebral aneurysm and its rupture are more prevalent in postmenopausal women and have been postulated to be hormonally influenced. The goal of this study was to investigate the associations of female-specific factors, including reproductive life span, age at menarche, and age at menopause, with the incidence of aneurysmal subarachnoid hemorrhage (aSAH) in women.

METHODS

Participants in the Nurses' Health Study were followed up from 1980 or the time of reaching menopause until 2018. Only women with natural menopause or surgical menopause due to bilateral oophorectomy were included. Reproductive life span was defined by subtracting the age at menarche from the age at menopause. Multivariable-stratified proportional hazards models were used to study reproductive life span, age at menarche, and age at menopause with the incidence of aSAH. Multivariable models were adjusted for age, race, smoking, hysterectomy, hypertension, hyperlipidemia, body mass index, hormone therapy use, oral contraceptive use, and parity.

RESULTS

A total of 97,398 postmenopausal women with reproductive life span data were included; 138 participants developed aSAH, which was confirmed on medical record review by a physician. A shorter reproductive life span (≤35 years) was associated with a 2-fold higher incidence of aSAH after multivariable adjustment (hazard ratio [HR] 2.0 [95% CI 1.4-2.8]). Early age at menopause (age <45 years) was similarly associated with a higher risk of aSAH (HR 2.1 [95% CI 1.4-3.1]), but age at menarche was not. Use of oral contraceptives and postmenopausal hormone therapy was not associated with the incidence of aSAH.

DISCUSSION

An earlier age at menopause and a shorter reproductive life span duration (≤35 years) were associated with a higher risk of incident aSAH in women. No associations were noted for age at menarche, parity, oral contraceptive use, or postmenopausal therapy use.

Angiotensin-(1-7) as a Potential Therapeutic Strategy for Delayed Cerebral Ischemia in Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a substantial cause of mortality and morbidity worldwide. Moreover, survivors after the initial bleeding are often subject to secondary brain injuries and delayed cerebral ischemia, further increasing the risk of a poor outcome. In recent years, the renin-angiotensin system (RAS) has been proposed as a target pathway for therapeutic interventions after brain injury. The RAS is a complex system of biochemical reactions critical for several systemic functions, namely, inflammation, vascular tone, endothelial activation, water balance, fibrosis, and apoptosis. The RAS system is classically divided into a pro-inflammatory axis, mediated by angiotensin (Ang)-II and its specific receptor AT₁R, and a counterbalancing system, presented in humans as Ang-(1-7) and its receptor, MasR. Experimental data suggest that upregulation of the Ang-(1-7)/MasR axis might be neuroprotective in numerous pathological conditions, namely, ischemic stroke, cognitive disorders, Parkinson's disease, and depression. In the presence of SAH, Ang-(1-7)/MasR neuroprotective and modulating properties could help reduce brain damage by acting on neuroinflammation, and through direct vascular and anti-thrombotic effects. Here we review the role of RAS in brain ischemia, with specific focus on SAH and the therapeutic potential of Ang-(1-7).

Sex Differences in Cerebral Aneurysms and Subarachnoid Hemorrhage

Sex differences in cerebral aneurysm occurrence and characteristics have been well described. Although sex differences in outcomes following ischemic stroke have been identified, the effect of sex on outcomes following hemorrhagic stroke, and in particular, aneurysm treatment has been less studied. We describe the current state of knowledge regarding the impact of sex on treatment and outcomes of cerebral aneurysms. Although prior studies suggest that aneurysm prevalence and progression may be related to sex, we did not find clear evidence that outcomes following subarachnoid hemorrhage vary based on sex. Last, we identify areas for future research that could enhance understanding of the role sex plays in this context.

RNA Sequencing Data from Human Intracranial Aneurysm Tissue Reveals a Complex Inflammatory Environment Associated with Rupture

BACKGROUND

Intracranial aneurysm (IA) rupture leads to deadly subarachnoid hemorrhages. However, the mechanisms leading to rupture remain poorly understood. Altered gene expression within IA tissue is linked to the pathobiology of aneurysm development and progression. Here, we analyzed expression patterns of control tissue samples and compared them to those of unruptured and ruptured IA tissue samples using data from the Gene Expression Omnibus (GEO).

METHODS

FASTQ files for 21 ruptured IAs, 21 unruptured IAs, and 16 control tissue samples were accessed from the GEO database. DESeq2 was used for differential expression analysis in three comparisons: unruptured IA versus control, ruptured IA versus control, and ruptured versus unruptured IA. Genes that were differentially expressed in multiple comparisons were evaluated to find those progressively increasing/decreasing from control to unruptured to ruptured. Significance was tested by either analysis of variance/Gabriel or Brown-Forsythe/Games Howell (p < 0.05 was considered significant). We used additional RNA sequencing and proteomics datasets to evaluate if our differentially expressed genes (DEGs) were present in other studies. Bioinformatics analyses were performed with g:Profiler and Ingenuity Pathway Analysis.

RESULTS

In total, we identified 1768 DEGs, of which 318 were found in multiple comparisons. Unruptured versus control reflected vascular remodeling processes, while ruptured versus control reflected inflammatory responses and cell activation/signaling. When comparing ruptured to unruptured IAs, we found massive activation of inflammation, inflammatory responses, and leukocyte responses. Of the 318 genes in multiple comparisons, 127 were found to be significant in the multi-cohort correlation analysis. Those that progressively increased (70 genes) were associated with immune system processes, while those that progressively decreased (38 genes) did not return any gene ontology terms. Many of our DEGs were also found in the other IA tissue sequencing studies.

CONCLUSIONS

We found unruptured IAs relate more to remodeling processes, while ruptured IAs reflect more inflammatory and immune responses.

Kisspeptin-54 attenuates oxidative stress and neuronal apoptosis in early brain injury after subarachnoid hemorrhage in rats via GPR54/ARRB2/AKT/GSK3β signaling pathway

Oxidative stress-induced neuron apoptosis plays a crucial role in the early brain injury (EBI) after subarachnoid hemorrhage (SAH). Kisspeptin has been reported as antioxidant to reduce oxidative stress-induced neuronal cell death through G protein-coupled receptor 54 (GPR54). The goal of this study was to determine the neuroprotection of the Kisspeptin/GRP54 signaling pathway against EBI after SAH. Two hundred and ninety-two Sprague Dawley male rats were used and SAH was induced by the endovascular perforation. Exogenous Kisspeptin 54 (KP54) was delivered intranasally. Small interfering ribonucleic acid (siRNA) for endogenous KISS1, a selective GPR54 antagonist kisspeptin 234, or β-arrestin 2 siRNA for ARRB2 (a functional adaptor of GPR54) were administered intracerebroventricularly. Post-SAH evaluations included neurobehavioral tests, SAH grade, Western blot, immunofluorescence, Fluoro-Jade C, TUNEL, and Nissl staining. The results showed that endogenous KISS1 knockdown aggravated but exogenous KP54 (1.0 nmol/kg) treatment attenuated neurological deficits, brain oxidative stress, and neuronal apoptosis at 24 h after SAH. The benefits of KP54 persisted to 28 days after SAH, which significantly improved cognitive function in SAH rats. The GPR54 blockade or the ARRB2 knockout offset the neuroprotective effects of KP54 in SAH rats. In conclusion, our results suggested that administration of KP54 attenuated oxidative stress, neuronal apoptosis and neurobehavioral impairments through GPR54/ARRB2/AKT/GSK3β signaling pathway after SAH in rat. Thus, KP54 may provide an effective treatment strategy for SAH patients.

Subacute phase of subarachnoid haemorrhage in female rats: Increased intracranial pressure, vascular changes and impaired sensorimotor function

OBJECTIVE

Early brain injury (EBI) and delayed cerebral ischemia (DCI) after subarachnoid haemorrhage (SAH) has devastating consequences but therapeutic options and the underlying pathogenesis remain poorly understood despite extensive preclinical and clinical research. One of the drawbacks of most preclinical studies to date is that the mechanisms behind DCI after SAH are studied only in male animals. In this study we therefore established a female rat model of SAH in order to determine subacute pathophysiological changes that may contribute to DCI in females.

METHODS

Experimental SAH was induced in female rats by intracisternal injection of 300 μL of autologous blood. Sham operation served as a control. Neurological deficits and intracranial pressure measurements were evaluated at both 1 and 2 days after surgery. Additionally, changes in cerebral vascular contractility were evaluated 2 days after surgery using wire myography.

RESULTS

SAH in female rats resulted in sensorimotor deficits and decreased general wellbeing on both day 1 and day 2 after SAH. Intracranial pressure uniformly increased in all rats subjected to SAH on day 1. On day 2 the intracranial pressure had increased further, decreased slightly or remained at the level seen on day 1. Furthermore, female rats subjected to SAH developed cortical brain edema. Cerebral arteries, isolated 2 days after SAH, exhibited increased vascular contractions to endothelin-1 and 5-carboxamidotryptamine.

CONCLUSION

In the subacute phase after SAH in female rats, we observed increased intracranial pressure, decreased wellbeing, sensorimotor deficits, increased vascular contractility and cortical brain edema. Collectively, these pathophysiological changes may contribute to DCI after SAH in females. Previous studies reported similar pathophysiological changes for male rats in the subacute phase after SAH. Thus, prevention of these gender-independent mechanisms may provide the basis for a universal treatment strategy for DCI after SAH. Nevertheless, preclinical studies of potential therapies should employ both male and female SAH models.

Cerebrovascular disease in women

Cerebrovascular disease is a major cause of morbidity, mortality, and disability in women. The spectrum of disease differs between men and women, with women being particularly vulnerable to certain conditions, especially during specific periods of life such as pregnancy. There are several unique risk factors for cerebrovascular disease in women, and the influence of some traditional risk factors for stroke is stronger in women. Moreover, disparities persist in representation of women in clinical trials, acute intervention, and stroke outcomes. In this review, we aimed to explore the epidemiology, etiologies, and management of cerebrovascular disease in women, highlighting some of these differences and the growing need for sex-specific management guidelines and health policies.

Association between Anemia and Stroke in Females: A Nationwide, Population-Based Cohort Study in Taiwan

Optimal stroke prevention strategies for women should take into account specific sex-related stroke risk factors. Anemia is a common medical condition in females, particularly in women of reproductive age. This study investigated whether anemia is an independent risk factor for stroke in females in a population-based cohort study. We investigated newly diagnosed anemic female patients with no history of central nervous system disease, psychiatric disorders, traumatic brain injury, major operations or hemorrhagic diseases identified from the Taiwan National Health Insurance Research Database. Non-anemic matched controls (1:1) were selected based on a propensity score estimated using a logistic regression model that included demographic characteristics and comorbidities. A competing risk analysis was applied to estimate the stroke risk in anemic patients compared to that of their matched controls. In our study, the adjusted sub-distribution hazard ratios (aSHRs) of overall, hemorrhagic and ischemic stroke in anemic female patients aged <50 years were 1.35 (95% confidence interval (CI): 1.19-1.52, p < 0.001), 1.31 (95% CI, 1.09-1.56, p < 0.003), and 1.35 (95% CI, 1.15-1.58, p < 0.001), respectively, compared to non-anemic female controls. However, a positive association between anemia and stroke was not found for those aged ≥50 years. Similar results were observed when the follow-up age was limited to 50 years to reduce the potential effects of menopause on stroke. In conclusion, the present population-based cohort study found that anemia is a potential risk factor for overall, hemorrhagic and ischemic stroke in females of reproductive age.

Clinical analysis of young adult patients with ruptured intracranial aneurysms: a single-center study of 113 consecutive patients

OBJECTIVE

Intracranial aneurysm most frequently occurs in old aged patients; however, aneurysmal subarachnoid hemorrhage (SAH) has been occasionally reported in young adults. This study aimed to compare patients with intracranial aneurysms younger than 40 years with those ≥40 years and investigates the characteristics of their ruptured aneurysm.

METHODS

We retrospectively collected the data of 389 patients (103 patients aged 20 to 39 years; 286 patients aged above 40 years) who were treated for ruptured cerebral aneurysms between January 2008 and December 2018 at our institution.

RESULTS

The young adult patients were more often men and were smokers as compared to controls (63.1% vs. 39.2%, 40.5% vs. 36.0%, respectively). The young adult patients showed a tendency for lower Hunt and Hess grade, modified Fisher grade, less postoperative morbidity, and better clinical outcome. Aneurysm ruptures occurred most frequently in the anterior cerebral artery in both groups, but aneurysms ruptures in the internal carotid artery and posterior circulation was infrequent among young adult patients. The aneurysms in young adult patients were more often elongated or irregularly shaped (82.5% vs. 64.0%, respectively) and were significantly smaller (5.9 mm) than that in controls (6.8 mm).

CONCLUSIONS

Ruptured aneurysms of young adult patients have unique characteristics with regard to its preponderance in male smoker, elongated or irregular shape and relatively smaller size.

Role of pregnancy and female sex steroids on aneurysm formation, growth, and rupture: a systematic review of the literature

OBJECTIVE

Women have been shown to have a higher risk of cerebral aneurysm formation, growth, and rupture than men. The authors present a review of the recently published neurosurgical literature that studies the role of pregnancy and female sex steroids, to provide a conceptual framework with which to understand the various risk factors associated with cerebral aneurysms in women at different stages in their lives.

METHODS

The PubMed database was searched for "("intracranial" OR "cerebral") AND "aneurysm" AND ("pregnancy" OR "estrogen" OR "progesterone")" between January 1980 and February 2019. A total of 392 articles were initially identified, and after applying inclusion and exclusion criteria, 20 papers were selected for review and analysis. These papers were then divided into two categories: 1) epidemiological studies about the formation, growth, rupture, and management of cerebral aneurysms in pregnancy; and 2) investigations on female sex steroids and cerebral aneurysms (animal studies and epidemiological studies).

RESULTS

The 20 articles presented in this study include 7 epidemiological articles on pregnancy and cerebral aneurysms, 3 articles reporting case series of cerebral aneurysms treated by endovascular therapies in pregnancy, 3 epidemiological articles reporting the relationship between female sex steroids and cerebral aneurysms through retrospective case-control studies, and 7 experimental studies using animal and/or cell models to understand the relationship between female sex steroids and cerebral aneurysms. The studies in this review report similar risk of aneurysm rupture in pregnant women compared to the general population. Most ruptured aneurysms in pregnancy occur during the 3rd trimester, and most pregnant women who present with cerebral aneurysm have caesarean section deliveries. Endovascular treatment of cerebral aneurysms in pregnancy is shown to provide a new and safe form of therapy for these cases. Epidemiological studies of postmenopausal women show that estrogen hormone therapy and later age at menopause are associated with a lower risk of cerebral aneurysm than in matched controls. Experimental studies in animal models corroborate this epidemiological finding; estrogen deficiency causes endothelial dysfunction and inflammation, which may predispose to the formation and rupture of cerebral aneurysms, while exogenous estrogen treatment in this population may lower this risk.

CONCLUSIONS

The aim of this work is to equip the neurosurgical and obstetrical/gynecological readership with the tools to better understand, critique, and apply findings from research on sex differences in cerebral aneurysms.

Recanalization of Embolized Endovascular Intracranial Aneurysms and Changes in the Blood Viscosity: A Pilot Study

Background

The purpose of our research was to evaluate the relationships between blood viscosity and recanalization of coiled intracranial aneurysms.

Material/Methods

The study included consecutives patients treated endovascularly by a team of experienced neurosurgeons and neuroradiologists due to brain aneurysm. A total of 50 patients (the average age was 57.48 years, SD=13.71) were assigned to 2 groups: group A with recanalization (4 male and 8 female patients) and group B without recanalization (10 male and 28 female patients) were examined. All patients underwent a 6-month follow-up of the whole-blood viscosity test with a Brookfield DV III+pro cone-plate viscometer using the Rheocalc program. Differences between groups were assessed using the Statistica 12 computer program (StatSoft Inc., Tulsa, OK, USA).

Results

Studies have shown no significant difference in the age range between group A and B (P=0.31). In group A, higher viscosity values were found for whole blood [median: 4.14 dyn×sec/cm² (mPa×sec) quartile range 0.42], compared to group B [median: 3.92 dyn×sec/cm² (mPa×sec); quartile range 0.40; (P=0.04)]. This difference was significant (P=0.04). Additionally, the level of hematocrit was positively related with recanalization, the higher the hematocrit, the more frequent recanalization. A very strong and statistically significant relationship occurred between the frequency of recanalization and smoking (P<0.001).

Conclusions

The occurrence of higher values of whole blood viscosity which increase turbulent flow through the vessels may be a risk for recanalization of the coiled intracranial aneurysm.

Sex-related differences in wall remodeling and intraluminal thrombus resolution in a rat saccular aneurysm model

OBJECTIVE

Intracranial aneurysms (IAs) are more often diagnosed in women. Hormones and vessel geometry, which influences wall shear stress, may affect pathophysiological processes of the arterial wall. Here, the authors investigated sex-related differences in the remodeling of the aneurysm wall and in intraluminal thrombus resolution.

METHODS

A well-characterized surgical side-wall aneurysm model was used in female, male, and ovariectomized rats. Decellularized grafts were used to model highly degenerated and decellularized IA walls and native grafts to model healthy IA walls. Aneurysm growth and thrombus composition were analyzed at 1, 7, 14, and 28 days. Sex-related differences in vessel wall remodeling were compared with human IA dome samples of men and pre- and postmenopausal women.

RESULTS

At 28 days, more aneurysm growth was observed in ovariectomized rats than in males or non-ovariectomized female rats. The parent artery size was larger in male rats than in female or ovariectomized rats, as expected. Wall inflammation increased over time in all groups and was most severe in the decellularized female and ovariectomized groups at 28 days compared with the male group. Likewise, in these groups the most elastin fragmentation was seen at 28 days. In female rats, on days 1, 7, and 14, the intraluminal thrombus was mainly composed of red blood cells and fibrin. On days 14 and 28, macrophage and smooth muscle cell invasion inside the thrombus was shown, leading to the removal of red blood cells and deposition of collagen and elastin. On days 14 and 28, similar profiles of thrombus reorganization were observed in male and ovariectomized female rats. However, collagen content in thrombi and vessel wall macrophage content were higher in aneurysms of male rats at 28 days than in those of female rats. On day 28, thrombus coverage by endothelial cells was lower in ovariectomized than in female or male rats. Finally, analysis of human IA domes showed that endothelial cell coverage was lower in men and postmenopausal women than in younger women.

CONCLUSIONS

Aneurysm growth and intraluminal thrombus resolution show sex-dependent differences. While certain processes (endothelial cell coverage and collagen deposition) point to a strong hormonal dependence, others (wall inflammation and aneurysm growth) seem to be influenced by both hormones and parent artery size.

Sex differences in risk factors for aneurysmal subarachnoid haemorrhage: Systematic review and meta-analysis

BACKGROUND

Aneurysmal subarachnoid haemorrhage (aSAH) disproportionally affects women. We conducted a systematic review and meta-analysis to explore sex differences in aSAH risk factors.

METHODS

Case-control/cohort studies were searched to November 2017 with sex-specific risk factors for aSAH. Meta-analysis was performed when a risk factor was reported in ≥2 studies.

RESULTS

Of 31 studies, 22 were eligible for meta-analysis. Female sex was associated with greater odds of aSAH (HR_adjusted 1.90 [1.47-2.46]. There was no detectable difference between the sexes for hypertension (OR_adjusted: men 3.13 [2.26-4.34]; women 3.65 [2.87-4.63], p = .18), smoking (OR_adjusted: men 2.96 [1.68-5.21]; women 3.11 [1.21-7.97], p = .95), aSAH family history, systolic blood pressure, age and some genetic variations. Alcohol (OR_adjusted: men 1.50 [1.04-2.17]; women 0.83 [0.48-1.45], p = .003), high alanine aminotransferase levels, and some gene variants increased the risk of aSAH in men. Reproductive factors, divorce and some genetic variations increased the risk in women. High aspartate aminotransferase levels in men and, diabetes (OR_adjusted: men 0.57 [0.32-1.01]; women 0.24 [0.13-0.43], p = .01) and parity in women reduced aSAH risk.

CONCLUSION

We recommend sex-specific re-analysis of existing studies of aSAH risk factors. Known aSAH risk factors (hypertension, smoking and alcohol consumption) should be targeted to prevent aSAH in men and women. Registration PROSPERO (ID: CRD42018091521).

Age-Dependent Radiographic Vasospasm and Delayed Cerebral Ischemia in Women After Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

Recent literature suggests there are sex differences in delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Our study serves to compare sex differences in radiographic vasospasm, DCI, and clinical outcome after aSAH, and to determine whether there are age-dependent differences.

METHODS

A total of 328 patients with ruptured cerebral aneurysms were evaluated for radiographic vasospasm, clinical deterioration, cerebral infarction, and modified Rankin Scale-determined clinical outcome at 6 months to 1 year after rupture. Multivariate regression analyses were performed to evaluate the associations between these outcome measures and sex, adjusting for age, hypertension, aneurysm location, admission Hunt and Hess grade, and modified Fisher grade.

RESULTS

After multivariate adjustment, women had higher rates of radiographic vasospasm (β = 0.35; 95% confidence interval [CI], 0.068-0.63; P = 0.015), clinical deterioration (odds ratio [OR], 2.8; 95% CI, 1.3-6.0; P = 0.008) and cerebral infarction (OR, 2.4; 95% CI, 1.0-5.5; P = 0.039), but no difference was observed in follow-up modified Rankin Scale (mRS) outcome score at 6 months to 1 year (P = 0.96). Older women (age >55 years) have a higher rate of clinical deterioration than men in the same age group (OR, 3.5; 95% CI, 1.0-12; P = 0.043). In contrast, younger women (age ≤55 years) had increased radiographic vasospasm (β = 0.55; 95% CI, 0.17-0.93; P = 0.005) and worse mRS outcome score (β = 0.042; 95% CI, -0.021 to 1.1; P = 0.042) compared with men.

CONCLUSIONS

Female sex is associated with a higher risk of radiographic vasospasm, clinical deterioration, and cerebral infarction. Furthermore, this association appears to be age-dependent. This study further supports the unique role of sex, and highlights the need to better understand the possible role of female hormones in the development of complications of subarachnoid hemorrhage.

Delayed development of a de novo contralateral middle cerebral artery aneurysm in a patient with hyperimmunoglobulin E syndrome: A case report

A 50-year-old female patient with hyperimmunoglobulin E syndrome (HIES) presented initially at the age of 48 years with subarachnoid hemorrhage (SAH) from a ruptured left middle cerebral artery (MCA) bifurcation aneurysm, which was treated successfully with coiling and microsurgical clipping. Angiography and cross-sectional imaging did not indicate evidence of any additional intracranial aneurysm. However, the patient presented two years later with SAH secondary to a new ruptured right MCA bifurcation aneurysm, which was treated successfully with microsurgical clipping. This case provides further evidence that HIES places the cerebral vasculature at increased risk for cerebral aneurysm formation and that special considerations are indicated in managing and monitoring these patients.

Cerebral Aneurysms Differ in Patients with Hysterectomies

OBJECTIVE

Female sex is a well-known risk factor for aneurysm formation. Although the role of the ovaries and estrogen in aneurysm development has been supported, other organ-hormone pairs unique between sexes also may be implicated. In this study, we aimed to determine whether intracranial aneurysms microsurgically clipped in patients with previous hysterectomies exhibit any unique aneurysm characteristics from those without hysterectomies.

METHODS

Solitary aneurysms microsurgically treated by the senior author (M.T.L.) were included from a database of patients treated between January 2010 and April 2013 at a tertiary academic medical center. Only female patients and patients equal or older in age to the youngest patient in the hysterectomy group were included in the control group. Patient and aneurysm characteristics were compared using the χ² test for categorical variables and the independent t test analysis for continuous variables.

RESULTS

A total 233 patients were included in the study. Forty-three patients (19%) had undergone a previous hysterectomy; none had oophorectomies recorded. No difference in mean age (P = 0.89), hypertension (P = 0.38), alcohol use (P = 0.87), tobacco use (P = 0.22), or aneurysm location (P = 1) existed. However, patients in the hysterectomy group more often presented in a good neurologic condition before surgery (88% vs. 74%, P = 0.04) and had fewer large aneurysms (8% vs. 24%, P = 0.03). Also, fewer presented with a ruptured aneurysm (28%) then the nonhysterectomy group (51%) (P = 0.004).

CONCLUSIONS

Female patients with a surgical history of a hysterectomy have a lower rate of large aneurysms, present in better neurologic condition, and are less likely to present with a ruptured aneurysm than females without a hysterectomy.

Sex differences in delayed cerebral ischemia after subarachnoid hemorrhage

OBJECTIVE

In this study the authors sought to investigate the sex differences in the risk of delayed cerebral ischemia (DCI), delayed cerebral infarction, and the role of hormonal status.

METHODS

Ten studies included in the SAHIT (SAH International Trialists) repository were analyzed using a fitting logistic regression model. Heterogeneity between the studies was tested using I2 statistics, and the results were pooled using a random-effects model. Multivariable analysis was adjusted for the effects of neurological status and fixed effect of study. An additional model was examined in which women and men were split into groups according to an age cut point of 55 years, as a surrogate to define hormonal status.

RESULTS

A pooled cohort of 6713 patients was analyzed. The risk of DCI was statistically significantly higher in women than in men (OR 1.29, 95% CI 1.12–1.48); no difference was found with respect to cerebral infarction (OR 1.17, 95% CI 0.98–1.40). No difference was found in the risk of DCI when comparing women ≤ 55 and > 55 years (OR 0.87, 95% CI 0.74–1.02; p = 0.08) or when comparing men ≤ 55 and > 55 years (p = 0.38). Independent predictors of DCI were World Federation of Neurosurgical Societies (WFNS) grade, Fisher grade, age, and sex. Independent predictors of infarction included WFNS grade, Fisher grade, and aneurysm size.

CONCLUSIONS

Female sex is associated with a higher risk of DCI. Sex differences may play a role in the pathogenesis of DCI but are not associated with menopausal status. The predictors of DCI and cerebral infarction were identified in a very large cohort and reflect experience from multiple institutions.

Vasospasm-related complications after subarachnoid hemorrhage: the role of patients' age and sex

BACKGROUND

Outcome of aneurysmal subarachnoid hemorrhage (SAH) depends strongly on occurrence of symptomatic vasospasm (SV) leading to delayed cerebral ischemia (DCI). Various demographic, radiographic, and clinical predictors of SV have been reported so far, partially with conflicting results. The aim of this study was to analyze the role of patients' age and sex on SV/DCI risk, especially to identify age and sex-specific risk groups.

METHODS

All patients admitted with acute SAH during a 14-year-period ending in 2016 were eligible for this study. The study endpoints were the following: SV requiring spasmolysis, occurrence of DCI in follow-up computed tomography scans and unfavorable outcome at 6 months (modified Rankin scale > 2).

RESULTS

Nine hundred ninety-four patients were included in this study. The majority was female (666; 67%). SV, DCI, and unfavorable outcomes were observed in 21.5, 21.8, and 43.6% of the patients, respectively. Younger age (p < 0.001; OR = 1.03 per year decrease) and female sex (p = 0.025; OR = 1.510) were confirmed as independent predictors of SV. Regarding the sex differences, there were three age groups for SV/DCI risk ≤ 54, 55-74, and ≥ 75 years. Male patients showed earlier decrease in SV risk (at ≥ 55 vs. ≥ 75 years in females). Therefore, SAH females aged between 55 and 74 years were at the highest risk for DCI and unfavorable outcome, as compared to younger/older females (p = 0.001, OR = 1.77/p = 0.001, OR = 1.80). In contrast, their male counterparts did not show these risk alterations (p = 0.445/p = 0.822).

CONCLUSION

After acute SAH, female and male patients seem to show different age patterns for the risk of SV and DCI. Females aged between 55 and 74 years are at particular risk of vasospasm-related SAH complications, possibly due to onset of menopause.

CLINICAL TRIAL REGISTRATION NUMBER

DRKS, Unique identifier: DRKS00008749.

The Incidence and Characteristics of Patients with Small Ruptured Aneurysms (<5 mm) in Subarachnoid Hemorrhage

OBJECTIVE

Small unruptured aneurysms (<5 mm) are known for their very low risk of rupture, and are recommended to be treated conservatively. However, we encounter many patients with small ruptured aneurysms in the clinical practice. We aimed to investigate the incidence and characteristics of patients with small ruptured aneurysms.

METHODS

We reviewed all patients admitted to our hospital with subarachnoid hemorrhage from January 2005 to December 2015. The patients were divided into two groups: those with aneurysms <5 mm (group S) and those with aneurysms ≥5 mm (group L). The patient's age and sex, size and location of aneurysms, and risk factors such as hypertension, diabetes, alcohol use, and smoking were compared between the two groups.

RESULTS

Eight-hundred eleven patients were diagnosed with ruptured aneurysms, and 337 (41.6%) were included in group S. The mean size of all aneurysms was 6.10±2.99 mm (range, 0.7-37.7); aneurysms with a diameter of 4-5 mm accounted for the largest subgroup of all aneurysms. Female sex was significantly associated with the incidence of small ruptured aneurysms (odds ratio [OR] 1.50, 95% confidence intervals [CI] 1.02-2.19, p=0.037). Despite female predominance in the incidence of small ruptured aneurysms, the proportion of small ruptured aneurysms in young (<50 years) men was high. In men, there were no significant differences regarding the location of the aneurysms between group S and group L (p=0.267), with the most frequent location being the anterior communicating artery (ACoA) in both group S (50.9%) and group L (51.4%). However, in women, there were significant differences regarding the location of the aneurysms between group S and group L (p=0.023), with the most frequent locations being the ACoA (33.0%) in group S, and the posterior communicating artery (30.6%) in group L. In women, two locations were significantly associated with small (<5 mm) ruptured aneurysms: the ACoA (OR 2.14, 95% CI 1.01-4.54, p=0.047) and anterior cerebral artery (OR 3.54, 95% CI 1.19-10.54, p=0.023). Multiplicity and smoking were significantly associated with large (≥5 mm) ruptured aneurysms in women. The use of alcohol was related to small ruptured aneurysms in men over 50 years of age (OR 2.23, 95% CI 1.03-4.84, p=0.042).

CONCLUSION

In this study, small (<5 mm) ruptured aneurysms exhibited different incidences by age, sex, location, and risk factors such as multiplicity, smoking, and alcohol use.

MRI Characterization in the Acute Phase of Experimental Subarachnoid Hemorrhage

A number of mechanisms have been proposed for the early brain injury after subarachnoid hemorrhage (SAH). In this study, we investigated the radiographic characteristics and influence of gender on early brain injury after experimental SAH. SAH was induced by endovascular perforation in male and female rats. Magnetic resonance imaging was performed in a 7.0-T Varian MR scanner at 24 h after SAH. The occurrence and size of T2 lesions, ventricular dilation, and white matter injury (WMI) were determined on T2-weighted images (T2WI). The effects of SAH on heme oxygenase-1 and fibrin/fibrinogen were examined by Western blotting and immunohistochemistry. SAH severity was assessed using a MRI grading system, and neurological function was evaluated according to a modified Garcia's scoring system. T2 hyperintensity areas and enlarged ventricles were observed in T2WI coronal sections 24 h after SAH. The overall incidence of T2 lesions, WMI, and hydrocephalus was 54, 20, and 63%, respectively. Female rats had a higher incidence of T2 hyperintensity lesions and hydrocephalus, as well as larger T2 lesion volumes and higher average ventricular volume. SAH rats graded at 3-4 (our previously validated MRI grading scale) had larger T2 lesion volumes, more hydrocephalus, and worse neurological function compared with those graded at 0-2. In conclusion, T2 lesion, WMI, and hydrocephalus were the most prevalent MRI characteristics 24 h after experimental SAH. The T2 lesion area matched with fibrinogen/fibrin positive staining in the acute phase of SAH. SAH induced more severe brain injury in females compared to males in the acute phase of SAH.

A higher aneurysmal subarachnoid hemorrhage incidence in women prior to menopause: a retrospective analysis of 4,895 cases from eight hospitals in China

BACKGROUND

Subarachnoid hemorrhage (SAH) from a ruptured cerebral aneurysm is a devastating disease. Despite the risk factors, including hypertension, cigarette smoking and alcohol use, are more common in men, aneurysmal SAH belongs to a few diseases which the incidence is higher in women than in men. Sex hormones, especially estrogen, might be protective against this condition. Hormone replacement therapy (HRT) seems to be associated with a reduced risk for aneurysmal SAH. This study aims to know the prevalence of aneurysmal SAH of men and women at different ages.

METHODS

The age and gender information of 4,895 case of aneurysmal SAH (3,016 females, 1,879 males) were collected retrospectively from eight institutions in mainland China. The prevalence of aneurysmal SAH of men and women at different ages was analyzed.

RESULTS

The data showed women had a higher incidence of aneurysmal SAH than men starting at late thirties, and men might have a higher incidence of aneurysmal SAH than women only before 37-year-old.

CONCLUSIONS

Menopause may not be the only dominant factor causing higher incidence of aneurysmal SAH in women than in men.