Sex Differences in the Formation of Intracranial Aneurysms and Incidence and Outcome of Subarachnoid Hemorrhage: Review of Experimental and Human Studies

Abstract

Intracranial aneurysms are defined as pathological dilatations of cerebral arteries and rupture of intracranial aneurysms leads to subarachnoid hemorrhage (SAH). The goal of this review was to outline the sex differences in the formation and progression of intracranial aneurysms as well as sex-related differences in incidence and outcome of SAH. The literature review was performed using PubMed with a combination of these search terms: "subarachnoid hemorrhage," "incidence," "outcome," "sex," "gender," "male," "female," "experimental," "mice," and "rats." Studies written in English were used. Female sex is thought to be a risk factor for aneurysm formation, especially in postmenopausal age populations, suggesting the potential protective involvement of sex steroids. Female sex is also considered a risk factor for SAH occurrence. Although incidence and mortality are confirmed to be higher in females in most studies, they elucidated no clear differences in the functional outcome among SAH survivors. The effect of gender on the pathophysiology of SAH is not very well understood; nevertheless, the majority of pre-clinical studies suggest a beneficial effect of sex steroids in experimental SAH. Moreover, conflicting results exist on the role and effect of hormone replacement therapies and oral contraceptive pills on the incidence and outcome of human SAH. Sex differences exist in the formation of aneurysms as well as the incidence and mortality of SAH. Potential therapeutic effects of sex steroids have been replicated in many animal studies, but their potential use in the treatment of acute SAH in human populations needs more future study.

Aneurysmal isolated intracerebral hemorrhage and/or intraventricular hemorrhage without subarachnoid hemorrhage: a rare and perplexing scenario in neurosurgical practice

“…The hyperintensity appearance on noncontrast head CT is a reflection of electron density, and there is a linear relationship to the hematocrit and hemoglobin concentration [8]. The preliminary statistical analysis of our review showed that 57 % (12/21) of the patients were female, which is in accordance with the sex differences in the incidence of aSAH [12]. This might imply that sex does not play an important role in the incidence of this specific entity.…”

Extracellular Mitochondria in Cerebrospinal Fluid and Neurological Recovery After Subarachnoid Hemorrhage

“…Optimizing age-appropriate thresholds may eventually be necessary to better assess clinical outcomes in wider cohorts of patients. Additionally, other factors such as gender 18–21 and genetic background 22 may also influence SAH outcome. Future studies should further validate CSF JC1 endpoints in larger and separate patient cohorts.…”

The cerebral basal arterial network: morphometry of inflow and outflow components

“…; D'Souza, ; Turan et al. ). Variations in the anatomy of cerebral arteries are another important factor (Alnæs et al., ; Brown & Broderick, ).…”

“…Cerebrovascular accidents are the second leading cause of death (Feigin et al 2014) with increasing mortality and morbidity rates worldwide (D' Souza, 2015), including Australia and Sweden (Hankey et al 2002;Nieuwkamp et al 2014). Cerebrovascular aneurysms are associated with many factors such as tobacco smoking, hypertension, female sex and family history of cerebrovascular diseases (Ellamushi et al 2001;D'Souza, 2015;Turan et al 2016). Variations in the anatomy of cerebral arteries are another important factor (Alnaes et al, 2007;Brown & Broderick, 2014).…”