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.

The falling rates of hospital admission, case fatality, and population-based mortality for subarachnoid hemorrhage in England, 1999-2010

OBJECTIVE In this study, the authors examined trends in population-based hospital admission rates, patient-level case fatality rates (CFRs), and population-based mortality rates for nontraumatic (spontaneous) subarachnoid hemorrhage (SAH) in England. METHODS Population-based admission and mortality data (59,599 people admitted to a hospital with SAH, 1999-2010; 37,836 people whose death certificates mentioned SAH, 1995-2010) were analyzed. RESULTS Hospital admission rates for SAH per million population declined by 18.3%, from 100.4 (95% CI 97.6-103.1) in 1999 to 82.0 (95% CI 79.7-84.4) in 2010. CFRs at less than 30 days per 100 patients decreased by 18.2%, from 29.7 (95% CI 28.5-31.0) in 1999 to 24.3 (95% CI 23.2-25.5) in 2010. Population-based mortality rates per million population, where SAH was recorded as underlying cause of death on the death certificate, declined by 39.8%, from 41.2 (95% CI 39.5-43.0) in 1999 to 24.8 (95% CI 23.6-26.1) in 2010. CONCLUSIONS Population-based hospital admission rates, patient-level CFRs, and population-based mortality rates all declined between 1999 and 2010. Part of the decline in mortality rates for SAH is likely to be attributable to a decline in incidence. It is also, in part, attributable to increased survival after SAH. The available data do not allow us to compare the effects of different treatment methods for SAH on case fatality and mortality. During the period of study, mortality rates declined by almost 40%, and it is likely that there are a number of factors contributing to this substantial improvement in outcomes for SAH patients in England.

Evaluating innovation. Part 2: Development in neurosurgery

OBJECT Patients, practitioners, payers, and regulators are advocating for reform in how medical advances are evaluated. Because surgery does not adhere to a standardized developmental pathway, how the medical community accepts a procedure remains unclear. The authors developed a new model, using publication data and patterns, that quantifies this process. Using this technique, the authors identified common archetypes and influences on neurosurgical progress from idea inception to acceptance. METHODS Seven neurosurgical procedures developed in the past 15-25 years were used as developmental case studies (endovascular coil, deep brain stimulation, vagus nerve stimulation, 1,3-bis(2-chloroethyl)-l-nitrosourea wafer, and 3 radiosurgery procedures), and the literature on each topic was evaluated. A new metric the authors termed "progressive scholarly acceptance" (PSA) was used as an end point for community acceptance. PSA was reached when the number of investigations that refine or improve a procedure eclipsed the total number of reports assessing initial efficacy. Report characteristics, including the number of patients studied, study design, and number of authoring groups from the first report to the point of PSA, were assessed. RESULTS Publication data implicated factors that had an outsized influence on acceptance. First, procedural accessibility to investigators was found to influence the number of reports, number of patients studied, and number of authoring groups contributing. Barriers to accessibility included target disease rarity, regulatory restrictions, and cost. Second, the ease or difficulty in applying a randomized controlled trial had an impact on study design. Based on these 2 factors, 3 developmental archetypes were characterized to generally describe the development of surgery. CONCLUSIONS Common surgical development archetypes can be described based on factors that impact investigative methods, data accumulation, and ultimate acceptance by society. The approach and proposed terminologies in this report could inform future procedural development as well as any attempts to regulate surgical innovation.

Sinus pericranii: diagnosis and management in 21 pediatric patients

OBJECT

Sinus pericranii (SP) is a rare venous anomaly abnormally connecting the intracranial dural sinuses with the epicranial veins. In the present study the authors aimed to clarify this clinicoradiological entity, define the role of angiography in its preoperative assessment, and suggest a diagnostic-therapeutic flow chart for management purposes.

METHODS

The authors retrospectively reviewed the clinical charts and neuroimages of 21 patients with SP. All patients underwent brain MRI, MR venography, and craniocerebral CT. Diagnostic digital subtraction angiography was performed in 19 of 21 patients, and the SPs were categorized as dominant (draining the majority of the intracranial venous outflow) or accessory (draining only a minority of the intracranial venous outflow).

RESULTS

SP was median or paramedian in 20 patients and lateral in 1 patient. There were 5 dominant and 14 accessory SPs. The dominant SPs were not treated. Among the patients with accessory SP, 4 were not treated, 2 underwent surgical ligature, and 8 were treated endovascularly (with either transvenous or percutaneous embolization). No complications were observed, and symptoms disappeared after treatment in all cases.

CONCLUSIONS

Accepted guidelines or recommendations concerning the management, diagnosis, and treatment of SP are still lacking. The authors define here a diagnostic-therapeutic flow chart, in which angiography plays a crucial role in the classification of SP and choice of the optimal treatment. Only accessory SP is amenable to treatment, whereas dominant SP must be preserved. The endovascular approach is becoming increasingly relevant and has proven to be safe and effective.