Intracranial aneurysms and heredity

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.

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.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Intracranial Aneurysms: Pathology, Genetics, and Molecular Mechanisms

Intracranial aneurysms (IA) are local dilatations in cerebral arteries that predominantly affect the circle of Willis. Occurring in approximately 2-5% of adults, these weakened areas are susceptible to rupture, leading to subarachnoid hemorrhage (SAH), a type of hemorrhagic stroke. Due to its early age of onset and poor prognosis, SAH accounts for > 25% of years lost for all stroke victims under the age of 65. In this review, we describe the cerebrovascular pathology associated with intracranial aneurysms. To understand IA genetics, we summarize syndromes with elevated incidence, genome-wide association studies (GWAS), whole exome studies on IA-affected families, and recent research that established definitive roles for Thsd1 (Thrombospondin Type 1 Domain Containing Protein 1) and Sox17 (SRY-box 17) in IA using genetically engineered mouse models. Lastly, we discuss the underlying molecular mechanisms of IA, including defects in vascular endothelial and smooth muscle cells caused by dysfunction in mechanotransduction, Thsd1/FAK (Focal Adhesion Kinase) signaling, and the Transforming Growth Factor β (TGF-β) pathway. As illustrated by THSD1 research, cell adhesion may play a significant role in IA.

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.

Pediatric Intracranial Aneurysms: Favorable Outcomes Despite Rareness and Complexity

OBJECTIVE

Pediatric intracranial aneurysms (IAs) are rare and differ from their adult counterparts in terms of their aneurysmal characteristics, presentation, treatment, and outcomes. Their treatment is often more difficult and complex compared with that of adults. However, studies outlining the clinical effect of pediatric IAs remain sparse.

METHODS

We retrospectively reviewed the data from patients aged ≤18 years admitted to our hospital from 2000 to 2017 with a diagnosis of IAs.

RESULTS

From the sample of 8207 patients with an IA diagnosis, 26 patients with 33 IAs were involved. Our cohort included 17 males and 9 females, with a mean age of 12.5 years. The mean follow-up duration was 4 years and 3 months. Seven patients (26.92%) were assumed to have a traumatic origin for their IAs. Ruptured aneurysms were more common than unruptured ones (61.53% vs. 38.46%). Complex features were observed in 14 aneurysms (42.42%). Initially, microsurgical and endovascular treatment were both performed in 10 patients (38.46%). A good recovery was obtained in 16 patients (61.54%) as determined by the Glasgow outcome scale scores at the 6-month follow-up visits. The complete obliteration of aneurysms was observed in 17 patients (65.38%). Endovascular treatment was the initial treatment in 3 patients with incomplete obliteration.

CONCLUSIONS

The treatment of pediatric IAs is challenging and technically demanding owing to their discrete nature compared with adult IAs and the need for greater surgical skills. We found a male predominance, with internal carotid artery bifurcation as the most frequent location of the aneurysms. Despite the greater incidence of ruptured and complex aneurysm cases, many patients had experienced a good recovery at the 6-month follow-up examinations.

Unruptured intracranial aneurysms: An updated review of current concepts for risk factors, detection and management

The management of patients with unruptured intracranial aneurysms (UIAs) is a complex clinical challenge and constitutes an immense field of research. While a preponderant proportion of these aneurysms never rupture, the consequences of such an event are severe and represent an important healthcare problem. To date, however, the natural history of UIAs is not completely understood and there is no accurate means to discriminate the UIAs that will rupture from those that will not. Yet, a good understanding of the recent evidence and future perspectives is needed when advising a patient with IA to tailor any information to the given patient's level of risk and psychoaffective status. Thus, this review addresses the current concepts of epidemiology, risk factors, detection and management of UIAs.

Management of aneurysmal subarachnoid hemorrhage: State of the art and future perspectives

Background:

Aneurysmal subarachnoid hemorrhage (SAH) accounts for 5% of strokes and carries a poor prognosis. It affects around 6 cases per 100,000 patient years occurring at a relatively young age.

Methods:

Common risk factors are the same as for stroke, and only in a minority of the cases, genetic factors can be found. The overall mortality ranges from 32% to 67%, with 10–20% of patients with long-term dependence due to brain damage. An explosive headache is the most common reported symptom, although a wide spectrum of clinical disturbances can be the presenting symptoms. Brain computed tomography (CT) allow the diagnosis of SAH. The subsequent CT angiography (CTA) or digital subtraction angiography (DSA) can detect vascular malformations such as aneurysms. Non-aneurysmal SAH is observed in 10% of the cases. In patients surviving the initial aneurysmal bleeding, re-hemorrhage and acute hydrocephalus can affect the prognosis.

Results:

Although occlusion of an aneurysm by surgical clipping or endovascular procedure effectively prevents rebleeding, cerebral vasospasm and the resulting cerebral ischemia occurring after SAH are still responsible for the considerable morbidity and mortality related to such a pathology. A significant amount of experimental and clinical research has been conducted to find ways in preventing these complications without sound results.

Conclusions:

Even though no single pharmacological agent or treatment protocol has been identified, the main therapeutic interventions remain ineffective and limited to the manipulation of systemic blood pressure, alteration of blood volume or viscosity, and control of arterial dioxide tension.

THSD1 (Thrombospondin Type 1 Domain Containing Protein 1) Mutation in the Pathogenesis of Intracranial Aneurysm and Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

A ruptured intracranial aneurysm (IA) is the leading cause of a subarachnoid hemorrhage. This study seeks to define a specific gene whose mutation leads to disease.

METHODS

More than 500 IA probands and 100 affected families were enrolled and clinically characterized. Whole exome sequencing was performed on a large family, revealing a segregating THSD1 (thrombospondin type 1 domain containing protein 1) mutation. THSD1 was sequenced in other probands and controls. Thsd1 loss-of-function studies in zebrafish and mice were used for in vivo analyses and functional studies performed using an in vitro endothelial cell model.

RESULTS

A nonsense mutation in THSD1 was identified that segregated with the 9 affected (3 suffered subarachnoid hemorrhage and 6 had unruptured IA) and was absent in 13 unaffected family members (LOD score 4.69). Targeted THSD1 sequencing identified mutations in 8 of 507 unrelated IA probands, including 3 who had suffered subarachnoid hemorrhage (1.6% [95% confidence interval, 0.8%-3.1%]). These THSD1 mutations/rare variants were highly enriched in our IA patient cohort relative to 89 040 chromosomes in Exome Aggregation Consortium (ExAC) database (P<0.0001). In zebrafish and mice, Thsd1 loss-of-function caused cerebral bleeding (which localized to the subarachnoid space in mice) and increased mortality. Mechanistically, THSD1 loss impaired endothelial cell focal adhesion to the basement membrane. These adhesion defects could be rescued by expression of wild-type THSD1 but not THSD1 mutants identified in IA patients.

CONCLUSIONS

This report identifies THSD1 mutations in familial and sporadic IA patients and shows that THSD1 loss results in cerebral bleeding in 2 animal models. This finding provides new insight into IA and subarachnoid hemorrhage pathogenesis and provides new understanding of THSD1 function, which includes endothelial cell to extracellular matrix adhesion.

Familial Intracranial Aneurysms in Saudi Arabia: What Do We Need To Do?

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating event with significant morbidity and mortality. The incidence of SAH might be influenced by environmental factors but genetic predisposition is evolving as an important effector in the risk of development of intracranial aneurysms and rupture of aneurysms. This requires strategies for effective screening of family members at risk of developing such a phenotype, in order to deliver preventive treatment to these target lesions. We discuss the potential for implementing these strategies in the Saudi Arabian health system and the future implications on our care for such a vulnerable group of subjects.

Concordant Symptomatic Intracranial Aneurysm in a Monozygotic Twin: A Case Report and Review of the Literature

The development of an intracranial aneurysm (IA) is a multifactorial process, involving genetic and environmental factors. The presence of IA or aneurysmal subarachnoid hemorrhage (aSAH) in twins is particularly interesting, since both genetic and environmental factors can be studied. It also raises the question of whether, when one twin is affected, the other asymptomatic twin should be examined for an IA. We report on a monozygotic (MZ) twin-pair with aSAH in both twins and we review all reported cases of IA in MZ twins. Including our case, we found only 14 MZ twin-pairs in which both twins harbored an IA, suggesting a heavy underreporting in the medical literature. In this small group, a high concordance was noted in the sites of IAs. In MZ twins, the preferred sites for IAs are the branching arteries, while aneurysms arising from fusion arteries are rare. These sites differ from the preferential sites seen in series of familial IAs and series of sporadic IAs. We therefore hypothesize that the twinning process might play a significant role in the development of IAs in MZ twins. To further explore and substantiate this, the large twin registries should be studied. Although IAs in MZ twins with a negative family history for IAs should not be regarded as familial IAs, screening of the asymptomatic twin should be seriously considered if one MZ twin presents with an aSAH or an IA, because of the high fatality rates reported in asymptomatic (and not screened) MZ twin-halves.

[Treatment of grade 0 intracranial aneurysms: Retrospective study of 79 cases]

AIM

Without precise international recommendations, despite the advances of the ISUAA study, the superiority of microsurgery or endovascular treatment for unruptured intracranial aneurysm (UIA) over the natural history of this disease has not been proved. In this context, the authors evaluate their experience with the aim of assessing the results and risks of the different therapeutics and comparing them with the natural risk of this disease.

MATERIAL AND METHOD

From January 1993 to July 2000, 79 patients harboring 110 UIAs were treated. These patients were divided retrospectively into two groups. Group A included 45 operated patients. Group B included 37 patients treated with endovascular coiling. The therapeutic choice was not randomized and was approved by a multidisciplinary neurovascular staff.

RESULTS

The two populations were homogeneous in terms of age and sex. In group A, 12 patients presented early complications (26.6 %), with one death. In group B, 15.6 % of the patients presented an ischemic complication. After 1 year of follow-up, morbidity was 11.4 % in group A and 4.8 % for group B. Angiography found a partial recanalization in 12.5 % of the operated patients and in 33 % of the patients treated with endovascular coiling.

DISCUSSION

Many factors are involved in the therapeutic decision: UIA location and size and individual risks. Progress in both surgery and interventional neuroradiology has led to good results conforming with the data reported in the literature but does not demonstrate the superiority of one technique over another.

Epidemiology of intracranial aneurysms of Mississippi: a 10-year (1997-2007) retrospective study

BACKGROUND

Despite massive efforts, progress so far has been modest in isolating the genetic determinants for intracranial aneurysm (IA). More detailed epidemiology data might be essential for successful genome-wide association study. Here, we aimed to investigate epidemiology and identify the key risk factors associated with the pathogenesis of IA in a large specific population.

METHODS

We investigated the epidemiology and analyzed the risk factors of IA pathogenesis by using an International Classification of Diseases, Ninth Revision database search of the patients treated at the University of Mississippi Medical Center, Jackson, MS, within the past 10-year period (1998-2007). All recruited patients were interviewed to assess multiple risk factors and comorbidities (hypertension, tobacco abuse, females sex, diabetes mellitus, coronary artery disease, coronary obstructive pulmonary disease, alcohol abuse, stroke, hyperlipidemia, illicit drug use, and family history).

RESULT

In this retrospective study, we identified several significant risk factors among well-defined human subjects. The 3 major risk factors identified for our IA population are hypertension, tobacco abuse, and female sex. However, African American race was not a significant risk factor in our study. Furthermore, top two risk factors (hypertension, tobacco abuse) were found to be highly associated with familial cases.

CONCLUSIONS

In this study, using a specific and well-defined large population, we reported that some key risk factors were further confirmed to be strongly associated with the pathogenesis of IA whereas further investigation into racial factors is apparently needed. Our finding of the confounding effects of top risks with familial cases further complicated the genetic analysis of IA.

Molecular Genetics of Human Intracranial Aneurysms

Intracranial aneurysms (IAs) are the dilatations of blood vessels in the brain and pose potential risk of rupture leading to subarachnoid hemorrhage. Although the genetic basis of IAs is poorly understood, it is well-known that genetic factors play an important part in the pathogenesis of IAs. Therefore, the identifying susceptible genetic variants might lead to the understanding of the mechanism of formation and rupture of IAs and might also lead to the development of a pharmacological therapy. To elucidate the molecular pathogenesis of diseases has become a crucial step in the development of new treatment strategies. Although extensive genetic research and its potential implications for future prevention of this often fatal condition are urgently needed, efforts to elucidate the susceptibility loci of IAs are hindered by the issues bewildering the most common and complex genetic disorders, such as low penetrance, late onset, and uncertain modes of inheritance. These efforts are further complicated by the fact that many IA lesions remain asymptomatic or go undiagnosed. In this review, we present and discuss the current status of genetic studies of IAs and we recommend comprehensive genome-wide association studies to identify genetic loci that underlie this complex disease.

Risks of subarachnoid hemorrhage in siblings: a nationwide epidemiological study from Sweden

This nationwide study aimed to enhance available data by determining sibling risks of subarachnoid hemorrhage in a total population. The MigMed database at the Karolinska Institute, Stockholm, was used to identify all cases of subarachnoid hemorrhage diagnosed in Sweden between 1987 and 2001. Incidence ratios standardized for age, region, and socioeconomic status (SIRs) were calculated for persons with at least 1 sibling with subarachnoid hemorrhage. The reference group consisted of persons whose siblings had no subarachnoid hemorrhage. A total of 90 affected siblings were identified; their SIR of subarachnoid hemorrhage was 2.75. The risk decreased with increasing age in both men and women. Within the limits of the sample size, no sex differences could be observed. The relatively high sibling risks are likely to be due to heritable causes and shared environmental factors. Genetic causes possibly weigh more in early- than late-onset cases. This study shows the feasibility of carrying out nationwide family studies on subarachnoid hemorrhage.

Familial occurrence of brain arteriovenous malformations: a systematic review

BACKGROUND

Brain arteriovenous malformations (BAVMs) are thought to be sporadic developmental vascular lesions, but familial occurrence has been described. We compared the characteristics of patients with familial BAVMs with those of patients with sporadic BAVMs.

METHODS

We systematically reviewed the literature on patients with familial BAVMs. Three families that were found in our centre were added. Age, sex distribution and clinical presentation of the identified patients were compared with those in population based series of patients with sporadic BAVMs. Furthermore, we calculated the difference in mean age at diagnosis of parents and children to study possible anticipation.

RESULTS

We identified 53 patients in 25 families with BAVMs. Mean age at diagnosis of patients with familial BAVMs was 27 years (range 9 months to 58 years), which was younger than in the reference population (difference between means 8 years, 95% CI 3 to 13 years). Patients with familial BAVMs did not differ from the reference populations with respect to sex or mode of presentation. In families with BAVMs in successive generations, the age of the child at diagnosis was younger than the age of the parent (difference between means 22 years, 95% CI 13 to 30 years), which suggests clinical anticipation.

CONCLUSIONS

Few patients with familial BAVMs have been described. These patients were diagnosed at a younger age than sporadic BAVMs whereas their mode of presentation was similar. Although there are indications of anticipation, it remains as yet unclear whether the described families represent accidental aggregation or indicate true familial occurrence of BAVMs.

Evidence in favor of the contribution of genes involved in the maintenance of the extracellular matrix of the arterial wall to the development of intracranial aneurysms

Intracranial aneurysm is probably a complex disease with both genetic and non-genetic or environmental risk factors contributing to the etiology of the disease. A disruption of the extracellular matrix (ECM) of the arterial wall is a likely factor in the pathogenesis of intracranial aneurysms. We analyzed 44 potential candidate genes involved in the maintenance of the integrity of the ECM in 382 Dutch Caucasian patients with intracranial aneurysms and 609 Dutch Caucasian controls for 384 tag single nucleotide polymorphisms (SNPs) using the GoldenGate assay on an Illumina BeadStation 500 GX. We identified SNPs that were associated with intracranial aneurysms (P<0.01) in six of these 44 genes: serpine1 (SERPINE1, P=0.0008), transforming growth factor beta induced (TGFBI, P=0.0026), perlecan (HSPG2, P=0.0044), fibronectin (FN1, P=0.0069), fibrillin 2 (FBN2, P=0.0077) and alpha 1 type IV collagen (COL4A1, P=0.0087). In a second independent cohort of 310 Dutch Caucasian intracranial aneurysm patients and 336 Dutch Caucasian controls, the association for the HSPG2 gene [combined odds ratio (OR) 1.33, 95% confidence interval (CI) 1.13-1.57, P=6 x 10(-4)] was replicated. The population attributable risk (PAR) for this SNP is 19%. Combining the two cohorts still showed association for the SERPINE1 (combined OR 1.27, 95% CI 1.07-1.50, P=0.004, PAR 6%), FBN2 (combined OR 1.37, 95% CI 1.07-1.75, P=0.01, PAR 3%) and COL4A1 (combined OR 1.22, 95% CI 1.05-1.42, P=0.007, PAR 7%) genes. These PARs are likely to be overestimates as they are calculated from the joint analyses combining stages 1 and 2 of our association study. Our findings indicate that variation in genes involved in the maintenance of the integrity of the ECM of the arterial wall plays a role in susceptibility to intracranial aneurysms. These findings further support our hypothesis that diminished maintenance of the ECM of the arterial wall is important in the development of intracranial aneurysms.

Clinical features of familial moyamoya disease

OBJECTS

This study aims to clarify the genetic background of moyamoya disease by comparing clinical features between familial and sporadic cases to reveal the responsible genes for familial moyamoya disease.

METHODS

This study included 155 Japanese patients with moyamoya disease, which included 24 familial cases (10 family pedigrees) and 131 sporadic cases. Clinical features were compared between the familial and sporadic cases.

RESULTS AND CONCLUSION

A female preponderance was significantly more prominent in the familial than in the sporadic group (P=0.0421). Mean age at onset was significantly lower in familial than in sporadic cases (P=0.004). In eight parent-offspring pairs, mean age at onset was significantly lower in the second than in the first generation (P<0.0001). These results suggest that familial moyamoya disease is associated with genetic anticipation and female predominance and that a genetic analysis study focused on expanded triplet repeats may clarify the pathogenesis of the disease.

Anévrismes intracrâniens non rompus : que proposer ?

Intracranial unruptured aneurysm (ICUA) has become a common condition for patient consultation. The mortality rate after fissuration is estimated to be between 52% and 85.7%. The final therapeutic decision results from a balance between the risk of rupture and risks related to the aneurysmal exclusion. Analysis of the risk of rupture risk enables a classification of risk factors. Depending on the circumstances of diagnosis, we considered the ICUA at high risk of rupture for incidental ICUA larger than 7 mm and in the event of associated aneurysms. Classifying by morphologic features, high-risk ICUA were located in the vertebrobasilar system (RR: 4.4; 95%CI: 2.7-6.8), those with a size between 7 and 12 mm (RR: 3.3; 95%CO: 1.3-8.2), larger than 12 mm (RR: 17; 95%CI: 8-36.1), those that were multilobular or a larger size and those ones with a index P/L superior to 3.4 (risk x20). Familial ICUA would expose to a major rupture risk (2 to 7 times sporadic ICUA). Some systemic factors were related to ICUA rupture: arterial hypertension (RR: 1.46; 95%CI: 1.01-2.11) and smoking addiction (RR: 3.04; 95%CI: 1.21-7.66). After microsurgical exclusion, the morbidity and mortality rates were 10% and 2% respectively. Some microsurgical morbidity factors were identified: age (32%>65 years), size (14%>15 mm), vertebrobasilar location and temporary occlusion. The rupture incidence after microsurgical exclusion was estimated 0.26%/year. After endovascular exclusion, the morbidity and mortality rates were 8% and 1% respectively. The complete exclusion rate varied between 47% and 67%. The rupture risk was estimated at 0.9%/year. Treatment recommendations were classified into 3 categories.

Lack of an association between the angiotensin-converting enzyme insertion/deletion polymorphism and intracranial aneurysms in a Caucasian population in the United States

OBJECT

The identification of polymorphisms associated with an increase in the risk of developing disease is integral to the development of genetic biomarkers to identify individuals at risk. Based on reports indicating a role for angiotensin-converting enzyme (ACE) in the pathogenesis of intracranial aneurysms (IAs) as well as hypertension, an independent risk factor for IAs, the authors investigated the association between an insertion/deletion (I/D) polymorphism in the ACE gene and IAs in a Caucasian population in the US.

METHODS

The patient population consisted of 162 randomly selected Caucasian patients who underwent surgical repair of an IA at Memorial-Hermann Hospital (Houston, TX) and had no family history of the disease. The ACE I/D polymorphism was typed using polymerase chain reaction amplification of genomic DNA, and allele and genotype frequencies were compared between the patients with IAs and 143 healthy Caucasian volunteers (control group) by performing logistic regression and chi-square tests. The ACE I/D allele frequencies did not differ significantly between the patient and control populations. There were similar allele and genotype frequencies in male and female study participants in both patient and control populations. The authors found no evidence of an association between the allelic or genotypic distribution of the ACE I/D polymorphism and aneurysmal subarachnoid hemorrhage or unruptured IAs.

CONCLUSIONS

Contrary to findings in two European Caucasian populations (one British and one Polish), this polymorphism did not contribute to the risk of developing IAs in a Caucasian population in the US.

Anticipation and phenotype in familial intracranial aneurysms

BACKGROUND

In familial intracranial aneurysms there is evidence for genetic heterogeneity, probably from mutations at separate loci.

OBJECTIVES

To compare demographic and clinical features in patients of families with familial intracranial aneurysm and different patterns of inheritance; and to compare the ages of patients with subarachnoid haemorrhage (SAH) in affected parent-child pairs to determine whether there is anticipation.

METHODS

Pedigrees for 53 families with familial intracranial aneurysms were constructed, divided into patterns of inheritance suggestive or not suggestive of autosomal dominant transmission. Demographic and clinical features were compared. The age at time of SAH in affected parent-child pairs was compared using the Wilcoxon test.

RESULTS

No differences in demographic or clinical features were found between families compatible with an autosomal dominant pattern of inheritance and those with a non-dominant pattern. In families with affected members in two successive generations the age at time of SAH in parents was 55.2 years and in children 35.4 years (mean difference, 19.8 years, p<0.001).

CONCLUSIONS

Phenotypes are similar in families with and without a probable autosomal dominant pattern of inheritance. Thus in future genetic studies on familial intracranial aneurysms, stratification according to phenotype is not likely to be useful. Anticipation probably occurs, as affected parents are significantly older at the time of SAH than their affected children.

Unruptured intracranial aneurysms: benign curiosity or ticking bomb?

15 years ago, the treatment of incidentally discovered intracranial aneurysms was straightforward with a good evidence base behind it. When intracranial aneurysms were identified, people were referred to neurosurgeons who would offer surgical repair if the patient was in reasonable health and had a good life expectancy. Since that time, several studies have given contradictory evidence for what should be done with these lesions, and a new technique for the repair of aneurysms, endovascular coil embolisation, has been developed. Here we review the research and make several recommendations. First, incidentally discovered aneurysms in the anterior circulation less than 7 mm in size in people with no personal or family history of subarachnoid haemorrhage should be left untreated. Second, people with remaining life expectancy of less than 20 years or so (ie, those over age 60 years) should be informed that from a statistical point of view the benefits of treatment do not outweigh the risks. Third, in all other cases treatment with surgical clipping or coil embolisation should be advised. And finally, if surgical treatment is not feasible then medical hypotensive treatment may be a viable alternative.

Familial association of basilar bifurcation aneurysm and moyamoya disease--four case reports

Four patients presented with familial intracranial aneurysms and familial moyamoya disease, including one patient with both familial intracranial aneurysm and moyamoya disease. Basilar bifurcation aneurysms were present in two patients, moyamoya disease in one, and both basilar bifurcation aneurysm and moyamoya disease in one. These events are most likely to arise from different genetic abnormalities associated with basilar bifurcation aneurysm and moyamoya disease.

Incidence of familial intracranial aneurysms in 200 patients: comparison among Caucasian, African-American, and Hispanic populations

OBJECTIVE

Although the cause of cerebral aneurysms remains unclear, there is clear evidence that genetic predisposition plays a role. Ten percent of patients report an aneurysm in a first-degree family member. However, studies to date have largely involved Caucasian populations. Our goal was to characterize the familial aggregation of intracranial aneurysms in different ethnic groups.

METHODS

We began a prospective, single-center study on patients treated for intracranial aneurysms. Consenting subjects completed a detailed questionnaire regarding the medical history of family members. In families with two or more affected members, asymptomatic first-degree relatives were screened using computed tomographic or magnetic resonance angiography.

RESULTS

In a 2-year period, 292 patients with intracranial aneurysms were treated and 200 were enrolled; these included 124 Caucasians (62%), 34 African-Americans (17%), 38 Hispanics (19%), and 4 Asian-Americans (2%). Forty patients had a family history (20%). The incidence of family history among the different ethnic groups was similar; it was 19.4% in Caucasians, 20.6% in African-Americans, and 21.6% in Hispanics. One Asian-American patient had a family history. Visual inspection of the pedigrees supported autosomal-dominant inheritance with variable penetrance in all ethnic groups.

CONCLUSION

This study examined the incidence of familial cerebral aneurysms in three ethnic groups common to the United States: Caucasian, African-American, and Hispanic. We noted an equivalent rate of familial aneurysms, a finding that has immediate clinical implications. In families that have two or more members with cerebral aneurysms, screening of asymptomatic members should be recommended, regardless of ethnic background.

Familial intracranial aneurysms: an analysis of 346 multiplex Finnish families

BACKGROUND AND PURPOSE

Genetic risk factors are considered important in the development, growth, and rupture of intracranial aneurysms; however, few have been identified. We analyzed intracranial aneurysm families with at least 2 affected persons and determined relationships between affected persons and assessed the inheritance patterns of aneurysms.

METHODS

Families with > or =2 members with verified diagnoses of intracranial aneurysms were recruited from Kuopio and Helsinki, Finland. Families with a diagnosis of other heritable disorders that have associated intracranial aneurysms, such as autosomal dominant polycystic kidney disease, were excluded.

RESULTS

We identified 346 Finnish multiplex families with 160 (46.2%) male and 186 (53.8%) female index cases. There were a total of 937 aneurysm cases, with an average of 2.7 cases per family. The majority of the families had only 2 affected relatives (n=206; 59.5%), although there were families with up to 6 (n=10), 7 (n=1), 8 (n=1), or 10 (n=2) affected persons. The affected relatives of the index cases included 108 sisters, 116 brothers, 105 parents, 30 children, 15 grandparents, 102 aunts or uncles, and 64 cousins. Of the 937 affected persons, 569 (60.7%) were alive and available for genetic analysis. Inheritance patterns consistent with autosomal recessiveness were observed in 198 (57.2%), autosomal dominance in 126 (36.4%), and autosomal dominance with incomplete penetrance in 19 (5.5%) of the families.

CONCLUSIONS

The collection is the most extensive published to date and extends previous observations of familial aggregation that are consistent with a major gene effect.

Elastin polymorphism haplotype and intracranial aneurysms are not associated in Central Europe

BACKGROUND AND PURPOSE

The occurrence of intracranial aneurysms and of aneurysmal subarachnoid hemorrhage are influenced by genetic factors. Recent genomic studies in Japan have defined 3 chromosomal loci and 1 haplotype of elastin polymorphisms as important risk factors, both for affected sib pairs and sporadic patients.

METHODS

We have genotyped 2 single nucleotide polymorphisms in the elastin gene and evaluated their allelic association with intracranial aneurysm in a Central European sample of 30 familial and 175 sporadic patients and 235 population controls.

RESULTS

We found no allelic association between this elastin polymorphism haplotype and intracranial aneurysm.

CONCLUSIONS

Our data probably reflect increased genetic heterogeneity of intracranial aneurysm in Europe compared with Japan.

Family history and risk of subarachnoid hemorrhage: a case-control study in Nagoya, Japan

BACKGROUND AND PURPOSE

We sought to examine the relation between a family history of subarachnoid hemorrhage (SAH) and the risk of SAH by using a case-control study.

METHODS

Case subjects consisted of a consecutive series of 195 patients with spontaneous SAH, aged 30 to 79 years, with aneurysms confirmed by angiography and/or CT scan. Hospital and community control subjects were identified and matched to each case by sex and age (+/-2 years). Multiple conditional logistic regression was used to calculate the odds ratio (OR) and 95% interval (CI) adjusted for potential confounders.

RESULTS

Having a family member with SAH was significantly associated with an increased risk of SAH (OR, 4.0, 95% CI, 2.0 to 8.0), after adjusting for potential confounders. The risk for a positive family history of SAH was similar for men and women and was inversely related to the SAH patient's age. A maternal positive SAH history (OR, 5.4; 95% CI, 1.8 to 16.0) posed a much greater risk than a paternal positive history (OR, 3.2, 95% CI, 1.1 to 13.4).

CONCLUSIONS

A positive family history of SAH was significantly and strongly associated with the risk of SAH. To prevent the onset of SAH at a younger age, much more attention should be given to individuals with any family member (first-degree relatives) suffering SAH episodes.

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.

Search for intracranial aneurysm susceptibility gene(s) using Finnish families

BACKGROUND

Cerebrovascular disease is the third leading cause of death in the United States, and about one-fourth of cerebrovascular deaths are attributed to ruptured intracranial aneurysms (IA). Epidemiological evidence suggests that IAs cluster in families, and are therefore probably genetic. Identification of individuals at risk for developing IAs by genetic tests will allow concentration of diagnostic imaging on high-risk individuals. We used model-free linkage analysis based on allele sharing with a two-stage design for a genome-wide scan to identify chromosomal regions that may harbor IA loci.

METHODS

We previously estimated sibling relative risk in the Finnish population at between 9 and 16, and proceeded with a genome-wide scan for loci predisposing to IA. In 85 Finnish families with two or more affected members, 48 affected sibling pairs (ASPs) were available for our genetic study. Power calculations indicated that 48 ASPs were adequate to identify chromosomal regions likely to harbor predisposing genes and that a liberal stage I lod score threshold of 0.8 provided a reasonable balance between detection of false positive regions and failure to detect real loci with moderate effect.

RESULTS

Seven chromosomal regions exceeded the stage I lod score threshold of 0.8 and five exceeded 1.0. The most significant region, on chromosome 19q, had a maximum multipoint lod score (MLS) of 2.6.

CONCLUSIONS

Our study provides evidence for the locations of genes predisposing to IA. Further studies are necessary to elucidate the genes and their role in the pathophysiology of IA, and to design genetic tests.

Influence of smoking, hypertension, and sex on the phenotypic expression of familial intracranial aneurysms in siblings

OBJECTIVE

To investigate the effects of smoking, hypertension, and sex on the phenotypic expression of familial intracranial aneurysms (FIAs).

METHODS

We retrospectively reviewed the case records of 806 consecutive patients undergoing aneurysm surgery at our institution (1986-1995) and discovered 24 families with at least two affected siblings. Prevalence rates for the smoking, hypertension, and sex risk factors in these nuclear families were compared with those of patients with sporadic intracranial aneurysms (SIAs) and population-based control patients.

RESULTS

Affected family members with FIAs exhibited prevalence rates of smoking and hypertension (74% and 43%, respectively) that tended to be higher than those of population-based control patients (52% [P < 0.005] and 36% [P = not significant (NS)], respectively) and comparable to those of patients with SIAs (64% [P = NS] and 40% [P = NS], respectively). A positive association existed between FIA formation and female sex but was somewhat less strong than that observed in the SIAs (59% FIAs, 71% SIAs, 50% control patients). In addition, the prevalence rates of smoking, hypertension, and female sex were higher in affected family members with FIAs than in their unaffected siblings (58% [P < 0.05], 28% [P = 0.06], and 39% [P < 0.05], respectively). Individuals in families with expressed FIAs who had high aneurysmal penetrance had a greater tendency to be smokers, hypertensive, and female (74%, 59%, and 55%, respectively) than did their low-penetrance counterparts (61% [P = 0.1], 27% [P < 0.05], and 45% [P = NS], respectively).

CONCLUSION

Together these data suggest that hypertension, smoking, and female sex increase the likelihood that a member of a family with an expressed FIA will have an aneurysm. These observations may prove helpful in guiding the use of screening studies and encouraging education about the potential risks of continued tobacco use and untreated hypertension in this patient cohort.

Subarachnoid haemorrhage: epidemiology, risk factors, and treatment options

The present review focuses on subarachnoid haemorrhage (SAH) secondary to the rupture of an intracranial aneurysm, a condition with a high case fatality rate. Additionally, many of the surviving patients are left with significant disabilities. Risk factors for aneurysmal SAH include both genetic and acquired conditions. The most common presenting symptom is sudden onset of severe headache. Since headache is very common in the general population, it is not unusual that SAH is misdiagnosed at its onset with often catastrophic consequences. Unlike other acute neurological disorders such as brain injury, in which patient outcome is closely related to the extent of the injury occurring at the time of the trauma, patients with aneurysmal SAH are at risk of subsequent deterioration from 'avoidable' complications such as rebleed, vasospasm, hydrocephalus, and several other non-neurological general medical complications. Thus, the critical care management of the patient with SAH is of utmost importance in order to maximise the chances of satisfactory recovery. Although surgical clipping of the ruptured aneurysm remains the gold standard therapy, with the continuing refinement of endovascular techniques, a new, 'less invasive' option is now available, especially for patients considered poor surgical candidates.

Intracranial aneurysms and arterial hypertension: a review and hypothesis

BACKGROUND

Intracranial aneurysms and systemic arterial hypertension coexist in a high percentage of patients. The relationship between intracranial aneurysms and hypertension is poorly defined.

METHODS

Therefore, we reviewed the role of hypertension in the pathogenesis of saccular aneurysms as previously reported in clinical, experimental, and autopsy studies.

RESULTS

Among 24 relevant clinical and/or autopsy studies, the mean incidence of pre-existing hypertension was 43.5% in aneurysm patients compared to 24.4% in the normal population. Although definitive evidence is lacking, data from multiple types of investigations indicate that systemic arterial hypertension creates a greater risk for the development of intracranial aneurysms than previously believed. The underlying pathophysiological mechanism(s) are also poorly defined.

CONCLUSIONS

We propose a unifying hypothesis: Endothelial injury, occlusion of the vasa vasorum, and disruption of the synthesis of collagen and elastin are likely the most important factors in initiating the development of aneurysms. Chronic hypertension potentially affects all of these factors. Consequently, chronic hypertension may cause intimal thickening, necrosis of the tunica media, changes in the compositional matrix, and degeneration of the internal elastic lamina to develop in the arterial wall. These structural changes could cause a focal weakening in the arterial wall with resultant bulging. This theory accounts for the high incidence of intracranial aneurysms in the absence of any known associated hereditary or connective-tissue disease. Nor does it exclude the possibility of other etiological factors. From the perspective of prevention, however, it offers clear opportunities for prophylaxis.

Clinical features of intracranial aneurysms in siblings

OBJECTIVE

Among the family members of patients with aneurysmal subarachnoid hemorrhage (SAH), siblings have been documented to be at high risk of SAH and to have a high prevalence of unruptured aneurysms. We studied the distinctive features of aneurysms in siblings and attempted to determine the risk of rupture.

METHODS

We analyzed detailed data on 159 patients with siblings who had ruptured and unruptured aneurysms in 77 families from throughout Japan.

RESULTS

Seventy-three percent of the patients were female, and the mean age at the time of rupture was 55.6 years. In 39 families, two or more siblings had SAH. Eighty of 107 patients with ruptured aneurysms and 28 of 52 with unruptured aneurysms had a family history of SAH in siblings (P = 0.0082). Multiple and mirror-image aneurysms were found in 42 and 21 patients, respectively. Among 218 aneurysms, middle cerebral artery aneurysms were the most common type (43%). Anterior communicating artery aneurysms were underrepresented (15%). There were significantly more ruptured than unruptured anterior communicating artery aneurysms, compared with other aneurysms (P = 0.01).

CONCLUSION

The clinical features of aneurysms in siblings in this population agreed well with those reported for familial intracranial aneurysms and SAH, except for the age at the time of rupture. It is suggested that the risk of rupture is greater when patients with unruptured aneurysms have siblings with aneurysmal SAH and/or anterior communicating artery aneurysms.

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.

Inflammation and intracranial aneurysms

OBJECTIVE

An intracranial aneurysm is an important acquired cerebrovascular disease that can cause a catastrophic subarachnoid hemorrhage. Despite modern therapy, most patients die or are left disabled as a direct result of a severe initial hemorrhage. The development of more effective treatment strategies depends on understanding the fundamental biology of cerebral aneurysms. The purpose of the present study is to determine whether inflammation or immunological reaction occurs in cerebral aneurysms.

METHODS

Aneurysm tissue was collected at the time of microsurgical repair from 23 unruptured and 2 ruptured aneurysms (25 patients) and compared with 11 control basilar arteries harvested at autopsy. Immunohistochemistry was used to localize complement (C3c, C9), immunoglobulins (IgG, IgM), vascular cell adhesion molecule-1, macrophages and monocytes (CD68), T lymphocytes (CD3), and B lymphocytes (CD20).

RESULTS

Complement (C3c, P < 0.0001; C9, P = 0.0017), immunoglobulin (IgG, P = 0.0013; IgM, P = 0.031), vascular cell adhesion molecule-1 (P = 0.0022), macrophages (CD68, P = 0.004), and T lymphocytes (CD3, P = 0.0004) were all frequently present in the wall of aneurysm tissue but were rarely identified in control basilar arteries. A few B lymphocytes (CD20, P = 0.41) were found in aneurysm tissue, but none were found in the basilar arteries.

CONCLUSION

Extensive inflammatory and immunological reactions are common in unruptured intracranial aneurysms and may be related to aneurysm formation and rupture.

Management of intracranial aneurysms

Intracranial aneurysms are lesions commonly encountered by neurosurgeons, usually as a result of subarachnoid hemorrhage. The preferred treatment of these aneurysms is either surgical clipping or endovascular coiling, both of which eliminate the aneurysm from the normal circulation to prevent aneurysmal enlargement or additional hemorrhage. Despite advances over the last several decades in the understanding of intracranial aneurysms, morbidity from treatment of these lesions remains significant. This review will discuss the epidemiology, anatomy and pathophysiology, clinical and radiographic diagnosis, various treatment options, and potential complications from aneurysm treatment.

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.

Genetics of stroke--a review

Evidence from twin and family shows that genetic factors contribute to the risk of stroke and that their role may be at least as important in stroke as in coronary heart disease. Additional support for the significance of genetic factors comes from other findings such as epidemiological data showing phenotypic heterogeneity of stroke, genetic influence on many of the risk factors for stroke, and racial and geographic differences in morbidity and mortality in stroke victims. Yet, apart from the reported associations of a small number of cases with Mendelian cerebrovascular diseases, only a few studies have directly investigated gene markers or molecular genetics of stroke. This review presents the existing evidence on the genetic background of stroke and discusses results from the genetic studies of stroke published to date.