Outcome in familial subarachnoid hemorrhage

Screening for Intracranial Aneurysms in Individuals with a Positive First-Degree Family History: A Systematic Review

BACKGROUND

Subarachnoid hemorrhage secondary to rupture of an intracranial aneurysm (IA) is a devastating condition with high morbidity and mortality. Individuals with a positive family history of aneurysmal subarachnoid hemorrhage (aSAH) or IA can have an increased risk for aSAH or IA themselves. Screening is currently recommended in families with ≥2 affected first-degree relatives. We sought to assess the usefulness and cost-effectiveness of IA screening in individuals with a positive first-degree family history, relative to the number of family members affected.

METHODS

We performed a systematic literature search using PubMed and Google Scholar and identified additional studies by reviewing reference lists. Only original studies and review papers were considered. We excluded genetic diseases associated with IA and studies with unclear data concerning the number of first-versus second-degree relatives affected.

RESULTS

This review included 37 articles. Individuals with ≥2 affected first-degree relatives had a greater prevalence of IA (average 13.1% vs. 3% in the general population). Similarly, we found a greater prevalence of IA in individuals with ≥1 affected first-degree relative (average 4.8%, up to 19% in individuals with additional risk factors). The risk of aSAH also was increased in both categories. Recent studies stressed the importance of serial screening over time and suggested that such screening can be cost-effective in persons with only one first-degree relative with IA or aSAH.

CONCLUSIONS

While current guidelines do not recommend screening individuals with ≥1 first-degree relative affected, we found strong arguments in favor of this approach.

Patient and aneurysm characteristics in familial intracranial aneurysms. A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Patient and aneurysm characteristics have been reported to differ between patients with familial and non-familial intracranial aneurysms (IAs), although results are inconsistent. We systematically reviewed and meta-analyzed the literature to identify and quantify patient- and aneurysm characteristics associated with familial IAs.

METHODS

We searched PubMed and EMBASE for case-control and cohort studies comparing patient- and aneurysm characteristics between familial and non-familial IAs. Two observers independently assessed study eligibility and appraised quality with the Newcastle Ottawa Scale. With univariable weighted linear regression analysis we calculated β-coefficients with corresponding 95% confidence intervals (CIs) for ruptured and unruptured IAs combined and for ruptured IAs only. Heterogeneity was assessed with Higgins I2.

RESULTS

A total of 15 articles were included in the meta-analysis in which 16,346 patients were analyzed with a total of 14,225 IAs. For ruptured and unruptured IAs combined, multiple IAs were more prevalent in familial (28.5%) than in non-familial IAs (20.4%; β = 0.10, 95% CI, 0.04 to 0.16; I2 0%). For ruptured IAs only, in familial patients IAs were more prevalent on the middle cerebral artery (41.1% versus 29.5%; β = 0.12, 95% CI, 0.01 to 0.24; I2 12%) and ruptured at a younger age (46.5 years versus 50.8 years; β = -5.00, 95% CI, -9.31 to -0.69; I2 98%) than in non-familial patients. No significant differences were found for the proportion of women, size of the aneurysm at time of rupture, smoking or hypertension.

CONCLUSION

These results suggest that characteristics of familial and non-familial IAs show considerable overlap, yet differ on specific aspects. However, results for age at rupture showed considerable heterogeneity. These findings should be taken into consideration for future etiological research into IAs.

A Review of the Genetics of Intracranial Berry Aneurysms and Implications for Genetic Counseling

Here we review the current understanding of the genetic architecture of intracranial berry aneurysms (IBA) to aid in the genetic counseling of patients at risk for this condition. The familial subtype of IBA, familial intracranial aneurysms (FIA), is associated with increased frequency of IBA, increased risk of rupture, and increased morbidity and mortality after rupture. Family history is the strongest predictor for the development of IBA. However, a genetic test is not yet available to assess risk within a family. Studies using linkage analysis, genome-wide association, and next-generation sequencing have found several candidate loci and genes associated with disease onset, but have not conclusively implicated a single gene. In addition to family history, a separate or concurrent diagnosis of autosomal dominant polycystic kidney disease is a strong genetic risk factor for IBA formation. We also discuss the relative risk for developing IBA in several Mendelian syndromes including vascular Ehlers-Danlos syndrome, Marfan syndrome, Neurofibromatosis Type I, and Loeys-Dietz syndrome.

Twin-like appearance of an unruptured intracerebral anterior communicating artery (ACom) aneurysm in a male sibling of a patient with a ruptured ACom aneurysm

BACKGROUND

Increased risk of intracranial aneurysm rupture with subsequent subarachnoid haemorrhage (SAH) is related to several possible factors, including first-grade familial aneurysms.

METHODS AND RESULTS

Here we present a case of one ruptured and one unruptured identical twin-like anterior communicating artery (ACom) aneurysm present in two male siblings, without any proven genetic predisposition. According to evidence-based scores, aneurysm rupture risk for the younger (51 years old) sibling (with an unruptured ACom aneurysm) would be low, leaving the decision for either treatment or clinical follow-up to the discretion of the treating physician.

CONCLUSIONS

From a clinical neurosurgical perspective, however, especially since his older brother suffered an aneurysmal SAH at age 57 (i.e. 6 life-years later) from a twin-like-appearing ACom aneurysm, in our opinion rupture seems almost inevitable, thus prompting treatment at an early stage.

The case for family screening for intracranial aneurysms

Given that relatives of patients with intracranial aneurysms (IAs) or subarachnoid hemorrhage have a greater risk of harboring an aneurysm, family screening has become a common practice in neurosurgery. Unclear data exist regarding who should be screened and at what age and interval screening should occur. Multiple factors including the natural history of IAs, the risk of treatment, the cost of screening, and the psychosocial impact of finding an aneurysm should be taken into account when family screening is considered. In this paper, the authors review the current literature regarding risk factors and natural history of sporadic and familial aneurysms. Based on these data the authors assess current recommendations for screening and propose their own recommendations.

Familial intracranial aneurysms

OBJECTIVE

Numerous studies have compared the characteristics of familial intracranial aneurysms with those of non-familial aneurysms. To better understand familial subarachnoid hemorrhage (SAH), we studied a series of patients with SAH who had at least one first-degree relative with SAH, and compared our results with those of previous studies.

METHODS

We identified patients treated for SAH at our hospital between January 1993 and October 2006 and analyzed those patients with one or more first-degree relatives with SAH. We retrospectively collected data from patients with a family history and searched for patients who had relatives with aneurysms or who had been treated at other hospitals for SAH.

RESULTS

We identified 12 patients from six families with at least two first-degree relatives with SAH. All patients had affected first-degree relatives; in five families, they were siblings. The mean age at the time of rupture was 49.75 years; in four families, the age difference was within 5 years. In five patients (42%), the aneurysm was located in the middle cerebral artery. Only one patient had an aneurysm in the anterior communicating artery.

CONCLUSION

In agreement with previous studies, our results showed that familial aneurysms, in comparison with non-familiar aneurysms, ruptured at a younger age and smaller size, had a high incidence in the middle cerebral artery, and were underrepresented in the anterior communicating artery. Interestingly, the age at the time of rupture was similar between relatives. Screening should be considered in the fifth or sixth decade for those who have a sibling with SAH.

Unruptured intracranial aneurysms: using evidence and outcomes to guide patient teaching

It is estimated that approximately 10 to 15 million Americans have intracranial aneurysms. Intracranial aneurysms are classified as either unruptured or ruptured. Advances in knowledge and technology are enhancing diagnosis, management, and outcomes associated with unruptured intracranial aneurysms. Optimal outcomes are achieved when aneurysms are treated before they rupture. If the aneurysm ruptures, the mortality rate ranges from 30% to 60%. A review of evidence regarding aneurysms, including the pathogenesis, risk factors, treatment options, and outcomes, is presented. Treatment options addressed include surgical clipping, endovascular coiling, or watchful waiting. Current evidence supports aggressive treatment for patients with previously ruptured aneurysms, large or symptomatic aneurysms, a family history of aneurysm rupture, a long life expectancy, and aneurysms demonstrating growth. Factors that favor watchful waiting include aneurysms that are small or located in the anterior circulation and in patients with a short life expectancy or comorbid medical conditions. Nurses are in an ideal position to use evidence and outcomes to provide accurate and current information on how to reduce the risks for rupture and evaluate treatment options.

Hypertensive heart disease

Left ventricular hypertrophy (LVH) and diastolic dysfunction (CHF-D) are the early manifestations of cardiovascular target organ damage in patients with arterial hypertension and signify hypertensive heart disease. Identification of hypertensive heart disease is critical, as these individuals are more prone to congestive heart failure, arrhythmias, myocardial infarction and sudden cardiac death. Regression of left ventricular (LV) mass with antihypertensive therapy decreases the risk of future cardiovascular events. The goal of antihypertensive therapy is to both lower blood pressure (BP) and interrupt BP-independent pathophysiologic processes that promote LVH and CHF-D. The purpose of this review is to summarize current and emerging approaches to the pathophysiology and treatment of hypertensive heart disease.

Subarachnoid hemorrhage: neurointensive care and aneurysm repair

Aneurysmal subarachnoid hemorrhage (SAH) is often a neurologic catastrophe. Diagnosing SAH can be challenging, and treatment is complex, sophisticated, multidisciplinary, and rarely routine. This review emphasizes treatment in the intensive care unit, surgical and endovascular therapeutic options, and the current state of treatment of major complications such as cerebral vasospasm, acute hydrocephalus, and rebleeding. Outcome assessment in survivors of SAH and controversies in screening of family members are discussed.

Antihypertensive drugs and the heart

Left ventricular hypertrophy (LVH) and diastolic dysfunction (CHF-D) are early signs of cardiac end-organ damage (hypertensive heart disease) in patients with arterial hypertension. The presence of LVH or CHF-D confers increased risk of cardiovascular morbidity and mortality in patients with hypertension. Regression of left ventricular mass with antihypertensive therapy is associated with reduction in cardiovascular events. Antihypertensive therapy should be geared to both lower blood pressure and specifically reverse the pathophysiologic processes that may be independent of actual blood pressure. This review summarizes current and emerging approaches to the treatment of individuals with hypertensive heart disease.

Regression of left ventricular hypertrophy: are there preferred drugs?

The presence of left ventricular hypertrophy (LVH) confers markedly increased risk of cardiovascular morbidity and mortality in patients with hypertension. Regression of left ventricular (LV) mass with antihypertensive therapy is associated with reduction in cardiovascular events. In studies based on monotherapy, among the classes of antihypertensive drugs that have been adequately tested, diuretics and angiotensin-converting enzyme inhibitors appear to be the most effective agents for reducing LV mass. New avenues of research, based on combination antihypertensive therapy and on a more sophisticated understanding of the molecular mechanisms of LVH, may yield new pharmacologic approaches to regressing LV mass.

Molecular pathogenesis of subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) results from leakage of blood into the subarachnoid space and carries high morbidity and mortality. However, there is limited understanding to date, of the risk factors, cellular, intermediate biochemical and genetic traits predisposing to SAH. Nevertheless, in conjunction with improved methods of diagnostic imaging and less invasive approaches to preventing aneurysmal rupture, there may be utility in gaining a better understanding of the pathogenesis and in identifying pre-disease markers. Additionally, it is not impossible that drugs of value (e.g. matrix or endothelial modifiers) could become available. Several different clinical subtypes can be recognised, distinguished by arterial or venous involvement, presence of unruptured arterial aneurysms, and apparently "sporadic" and "familial" occurrences. Epidemiological risk factors include alcohol consumption and smoking: hypertension is a risk factor for rupture. About 10% seem to reflect strong family history and this subset may be particularly illuminating with respect to the molecular pathogenesis. Haemodynamic stress and poor vascular structure may be the main mechanisms of pathogenesis. The epidemiological and statistical evidence for familial megaphenic genes and modifier genes is reviewed. This review focuses on the pathogenesis, as opposed to inflammatory response to SAH. It sets in context the roles of specific genes and their protein products, such as polycystin (PKD1), fibrillin (FBN1), collagen III (COL3A1), elastin (ELN), collagen IV, protease inhibitor or alpha1-antitrypsin (PI) and proteases. These considerations illustrate the shortfalls in current knowledge, the needs of future biochemical and cellular research and their potential implications for future prevention of this often fatal condition.

Familial aggregation of intracranial aneurysms in an Inuit patient population in Kalaallit Nunaat (Greenland)

OBJECTIVE

The incidence of subarachnoid hemorrhage (SAH) and intracranial aneurysm (IA) has been reported to be higher in Greenlandic Inuits than in Caucasian Danes, but the rate of familial aggregation in Inuits is unknown.

METHODS

This study retrospectively compared the rate of familial aggregation of SAH and IA (at least one first- or second-degree relative with presumed SAH and/or IA) in 120 Inuit patients from Greenland admitted to the Copenhagen University Hospital in Copenhagen, Denmark, from 1978 to 1998 with a diagnosis of ruptured IA with that in 1,037 Caucasian Danes admitted from 1978 to 1983.

RESULTS

Inuit patients had a much higher rate of familial history of SAH (23.1%) and of IA (9.6%) than Danish patients (4.3 and 1.6%, respectively). In both populations, familial SAH was associated with lower age at the time of aneurysm rupture. Danish patients with familial SAH showed a higher rate of middle cerebral artery aneurysms (40 versus 26% in sporadic SAH). In Inuit patients with familial and nonfamilial SAH, 42 and 38% of the aneurysms originated from the middle cerebral artery. The overall rate of multiple aneurysms was highest among Inuits, and in both populations, it was increased in the presence of a positive family history.

CONCLUSION

The rate of a positive family history of presumed SAH and IA is high among Inuits who present with SAH compared with Caucasian Danes who present with SAH. This finding, coupled with a higher rate of multiple aneurysms and younger age at presentation, suggests a potential genetic influence among Inuit families.

The detection and management of unruptured intracranial aneurysms

The incidence of subarachnoid haemorrhage (SAH) is 6-8 per 100 000 person years, peaking in the sixth decade. SAH, mostly due to rupture of an intracranial aneurysm, accounts for a quarter of cerebrovascular deaths. Aneurysms increase in frequency with age beyond the third decade, are 1.6 times more common in women and are associated with a number of genetic conditions. Prospective autopsy and angiographic studies indicate that between 3.6 and 6% of the population harbour an intracranial aneurysm. Studies have found an increased rate of SAH in first degree relatives of SAH patients (relative risk 3.7-6.6). In affected families, the most frequent relationship between sufferers is sibling to sibling. The rupture rate of asymptomatic aneurysms was thought to be 1-2% per annum, but the recent International Study of Unruptured Intracranial Aneurysms found that the rupture rate of small aneurysms was only 0.05% per annum in patients with no prior SAH, and 0.5% per annum for large (>10 mm diameter) aneurysms and for all aneurysms in patients with previous SAH. Non-invasive tests such as magnetic resonance angiography (MRA), computed tomographic angiography (CTA) and transcranial Doppler (TCD) have been advocated as alternatives to intra-arterial digital subtraction angiography to screen for aneurysms. Although all are promising techniques, the quality of data testing their accuracy is limited. Overall reported sensitivity for CTA and MRA (TCD is poorer) was 76-98% and specificity was 85-100%, but many subjects had an aneurysm or recent SAH, which could overestimate accuracy. CTA and MRA are much poorer methods for the detection of aneurysms <5 mm diameter, which account for up to one-third of unruptured aneurysms. Elective surgical clipping of asymptomatic aneurysms has a morbidity of 10.9% and mortality of 3. 8%. Treatment of aneurysms by Guglielmi coils, for which there is less long-term follow-up available, has a 4% morbidity and 1% mortality, but only achieves complete aneurysm occlusion in 52-78% of cases. There has been interest in screening for aneurysms, but the indication for, and cost effectiveness of screening are unclear because aneurysm prevalence varies, rupture rate is low, non-invasive imaging tests are not yet accurate enough to exclude small aneurysms and the morbidity and mortality for elective surgical treatment of unruptured aneurysms is high. There may be a limited role for investigation of high risk subgroups. Ideally, screening in such subgroups should be tested in a randomized trial. The avoidance of risk factors for aneurysms such as smoking, hypertension and hypercholesterolaemia should be part of the management of at-risk subjects.

Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage: follow up study based on national registries in Denmark

OBJECTIVE

To estimate the risk of occurrence of subarachnoid haemorrhage in first degree relatives (parents, siblings, children) of patients with subarachnoid haemorrhage.

DESIGN

Population based cohort study using data from the Danish National Discharge Registry and the Central Person Registry.

SUBJECTS

Incident cases of subarachnoid haemorrhage admitted to hospital from 1977 to 1995 (9367 patients) and their first degree relatives (14 781).

MAIN OUTCOME MEASURES

The incidence rate of subarachnoid haemorrhage was determined for the relatives and compared with that of the entire population, standardised for age, sex, and calendar period. This process was repeated for patients discharged from neurosurgery units, as diagnoses from these wards had high validity (93%).

RESULTS

18 patients had a total of 19 first degree relatives with subarachnoid haemorrhage during the study period, corresponding to a standardised incidence ratio of 2.9 (95% confidence interval 1.9 to 4.6). Patients discharged from neurosurgery wards had a higher standardised incidence ratio (4.5, 2.7 to 7.3).

CONCLUSIONS

First degree relatives of patients with subarachnoid haemorrhage have a threefold to fivefold increased risk of subarachnoid haemorrhage compared with the general population.

Asymptomatic familial cerebral aneurysms

PURPOSE

We evaluated the prevalence and features of cerebral aneurysms in the family members of people with asymptomatic aneurysms among 8680 participants undergoing magnetic resonance angiography.

METHODS

Of the 8680 participants, 380 had family histories of aneurysms and 8300 did not. The prevalence and features of asymptomatic aneurysms were compared in these two subgroups. In addition, the prevalence in all living first- or second-degree relatives was evaluated in 20 families.

RESULTS

The prevalence of asymptomatic aneurysms was 7.0% (606 of 8680 participants) overall and 10.5% (40 of 380 participants) and 6.8% (566 of 8300 participants) in the subgroups with and without family histories of aneurysms, respectively. The prevalence in the female participants with family histories of aneurysms (12.3%, 28 of 228 participants) was higher than that in the male participants with family histories of aneurysms (7.9%, 12 of 152 participants) (P < 0.0001). Compared with the entire group, this subgroup more commonly showed aneurysms situated at the junction of the internal carotid and posterior communicating arteries (P < 0.0005) and at the middle cerebral artery (P < 0.0001). The prevalence of aneurysms in 115 members of the 20 families was 33.9%. Although the members of 14 families with aneurysmal subarachnoid hemorrhage showed higher prevalence of ruptured and asymptomatic aneurysms (42.1%) than did the members of 6 families with only asymptomatic aneurysms (17.9%), the former had very low prevalence of asymptomatic aneurysms.

CONCLUSION

The prevalence of aneurysms is significantly elevated in family members of people with asymptomatic aneurysms. It is suggested that familial asymptomatic aneurysms are more likely to rupture in families having members with aneurysmal subarachnoid hemorrhage than in those without.

Familial cerebral aneurysms

Familial cerebral aneurysms are currently the subject of burgeoning interest. We review the pertinent, recent reports on this topic in the light of our study of 17 families with familial cerebral aneurysms. The prevalence of familial cerebral aneurysms ranges from 5-28%. The sex distribution displays a female bias. Mothers are more often affected than fathers and daughters more than sons. There is no site predilection for familial cerebral aneurysms but they tend to occur at the same (or mirror) site within families. The age at rupture of familial cerebral aneurysms is younger, especially in females, than for sporadic aneurysms. They tend to rupture within the same decade in families, and within five years of each other in identical twins. The size of ruptured familial cerebral aneurysms appears to be smaller, especially in women, than sporadic aneurysms. The pattern of inheritance is unknown. A poor outcome of rupture is more frequent in familial cerebral aneurysms cases than in sporadic ones. Angiographic screening of family members at risk, especially first degree relatives, appears justified.

Genetics of intracranial aneurysms

The etiology and pathogenesis of intracranial aneurysms are clearly multifactorial, with genetic factors playing an increasingly recognized role. Intracranial aneurysms have been associated with numerous heritable connective tissue disorders, which account for at least 5% of cases. Of these disorders, the most important are Ehlers-Danlos syndrome Type IV, Marfan's syndrome, neurofibromatosis Type 1, and autosomal dominant polycystic kidney disease; the association with intracranial aneurysms, however, has been firmly established only for polycystic kidney disease. Familial intracranial aneurysms are not rare but account for 7 to 20% of patients with aneurysmal subarachnoid hemorrhage and are generally not associated with any of the known heritable connective tissue disorders. First-degree relatives of patients with aneurysmal subarachnoid hemorrhage are at an approximately fourfold increased risk of suffering ruptured intracranial aneurysms, compared to the general population. Various possible modes of inheritance have been identified in families with intracranial aneurysms, suggesting genetic heterogeneity. Although the benefits have never been quantified, screening for asymptomatic intracranial aneurysms should be considered in families with two or more affected members. The yield of such a screening program may approximate 10%. Although it is unlikely that there is a single gene with major effect, much effort is currently being directed at locating intracranial aneurysm genes.

Family history of subarachnoid haemorrhage: supplemental value of scrutinizing all relatives

OBJECTIVE AND METHODS

To assess the validity of the family history obtained at the bedside of patients with recent subarachnoid haemorrhage by subsequently contacting all first and second degree relatives, with verification from medical record data.

RESULTS

In a prospectively collected series of 163 patients with recent subarachnoid haemorrhage the history or cause of death could be ascertained in 1259 (98%) of the first degree relatives and in 3038 (85%) of the second degree relatives. For first degree relatives only, the sensitivity of the family history at the bedside was 0.75 (95% confidence interval (95% CI) 0.35-0.97) and the positive predictive value was 0.55 (95% CI 0.23-0.83); for first and second degree relatives together the sensitivity was 0.58 (95% CI 0.28-0.85) and the positive predictive value was 0.64 (95% CI 0.31-0.89).

CONCLUSION

The accuracy of the family history taken at the bedside is modest; a more thorough collection of data is crucial if the decision is taken to screen relatives based on the family history.

Familial subarachnoid hemorrhage: distinctive features and patterns of inheritance

To delineate the distinctive features of familial subarachnoid hemorrhage, we compared gender and age at the time of subarachnoid hemorrhage, as well as site and number of aneurysms, in patients with familial subarachnoid hemorrhage (at least 1 first-degree relative with subarachnoid hemorrhage) and patients with sporadic subarachnoid hemorrhage (no subarachnoid hemorrhage in first- or second-degree relatives), in a prospective, hospital-based series of patients. In addition we studied the pattern of inheritance in 17 families with familial subarachnoid hemorrhage. Mean age at the time of hemorrhage in patients with the familial form was 6.8 years lower than that in those with the sporadic form, and middle cerebral artery aneurysms occurred more often in patients with familial disease. Sex distribution and number of aneurysms were similar in the two groups. Inheritance was compatible with autosomal dominant transmission in some families, and with autosomal recessive or multifactorial transmission in others. In our 5 families as well as in all 18 previously reported families with two affected generations, the age at the time of subarachnoid hemorrhage was invariably lower in later generations, which is suggestive of anticipation. We conclude that familial subarachnoid hemorrhage is a separate entity with occurrence at a young age, predilection for aneurysms of the middle cerebral artery, and variable modes of inheritance, including autosomal dominant inheritance with possible anticipation.