Genetics and Aneurysm Formation

Shedding the Light on the Natural History of Intracranial Aneurysms: An Updated Overview

The exact molecular pathways underlying the multifactorial natural history of intracranial aneurysms (IAs) are still largely unknown, to the point that their understanding represents an imperative challenge in neurovascular research. Wall shear stress (WSS) promotes the genesis of IAs through an endothelial dysfunction causing an inflammatory cascade, vessel remodeling, phenotypic switching of the smooth muscle cells, and myointimal hyperplasia. Aneurysm growth is supported by endothelial oxidative stress and inflammatory mediators, whereas low and high WSS determine the rupture in sidewall and endwall IAs, respectively. Angioarchitecture, age older than 60 years, female gender, hypertension, cigarette smoking, alcohol abuse, and hypercholesterolemia also contribute to growth and rupture. The improvements of aneurysm wall imaging techniques and the implementation of target therapies targeted against inflammatory cascade may contribute to significantly modify the natural history of IAs. This narrative review strives to summarize the recent advances in the comprehension of the mechanisms underlying the genesis, growth, and rupture of IAs.

Molecular basis and genetic predisposition to intracranial aneurysm

Intracranial aneurysms, also called cerebral aneurysms, are dilatations in the arteries that supply blood to the brain. Rupture of an intracranial aneurysm leads to a subarachnoid hemorrhage, which is fatal in about 50% of the cases. Intracranial aneurysms can be repaired surgically or endovascularly, or by combining these two treatment modalities. They are relatively common with an estimated prevalence of unruptured aneurysms of 2%-6% in the adult population, and are considered a complex disease with both genetic and environmental risk factors. Known risk factors include smoking, hypertension, increasing age, and positive family history for intracranial aneurysms. Identifying the molecular mechanisms underlying the pathogenesis of intracranial aneurysms is complex. Genome-wide approaches such as DNA linkage and genetic association studies, as well as microarray-based mRNA expression studies, provide unbiased approaches to identify genetic risk factors and dissecting the molecular pathobiology of intracranial aneurysms. The ultimate goal of these studies is to use the information in clinical practice to predict an individual's risk for developing an aneurysm or monitor its growth or rupture risk. Another important goal is to design new therapies based on the information on mechanisms of disease processes to prevent the development or halt the progression of intracranial aneurysms.

Systemic connective tissue abnormalities in patients with saccular intracranial aneurysms

OBJECTIVES

Our purpose was to identify the incidence and significance of markers of systemic connective tissue abnormalities (CTA) in patients with saccular intracranial aneurysms (SIA).

MATERIALS AND METHODS

This prospective case-control study included 199 consecutive patients with SIA (103 women and 96 men, mean age - 43.2 years) and 194 control patients - blood donors (108 - men, 86 - women, mean age - 38.4 years). Aneurysms were verified by conventional cerebral angiography. All patients were examined by the first author using a specially designed questionnaire and a standardized physical examination with special emphasis on systemic CTA.

RESULTS

Twelve markers of systemic CTA were significantly higher in patients with SIA than in controls: visible vessels on face and chest (59.8%), scoliosis (44.7%), varicose veins in legs (39.7%), flatfoot (34.6%), hyperextensibility of the skin (33.6%), spontaneous epistaxis (25.6%), easy bruising (20.6%), abdominal hernia (13.6%), periodontal disease (10.5%), chest deformations (7.5%), abdominal striae (3.5%), joint hypermobility (2.5%). A blinded validation study in a subset of 43 patients showed similar results. Among patients with SIA, 125 of 199 patients (62.8%) had at least three markers of systemic CTA compared with 23 (11.8%) of the controls (P < 0.0001, OR = 12.5, 95% CI 7.45-21.1). The mean number of markers of systemic CTA in patients with SIA was 3.07 and 1.17 in controls.

CONCLUSION

Patients with SIA have multiple markers of systemic connective tissue abnormalities. Systemic weakness of connective tissue represents a risk factor for development of SIA. Identification of these markers may help in detection of high-risk patients.

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.

Intracranial aneurysm and arachnoid cyst: a rare association between two cerebral malformations

Intracranial aneurysms and arachnoid cysts are cerebral disorders of a high prevalence. However, association between both malformations is a rare finding. The aim was to analyse this association with regard to the different clinical presentations according to the haemorrhage types, as well as the pathogenesis of this association. We searched the English language literature in MEDLINE database in order to include all manuscripts in which this association was found. A new case of a 55-year-old man with a large posterior communicating artery aneurysm and a middle cranial fossa arachnoid cyst presenting with headache and seizure was added to review of the literature and presented as an illustrative case. Nine cases were found. Six were male and three were female. The mean age was 42 years (range 29-66 years). All but one arachnoid cysts were located at middle cranial fossa, aneurysms arose from middle cerebral artery in three cases, internal carotid artery bifurcation in two cases, posterior communicating segment of carotid artery in two cases, anterior communicating artery in one case and azygos pericallosal artery in one case. Clinical presentation was related to aneurysmal rupture in six cases (subarachnoid haemorrhage in four, subdural haematoma in one and intracystic haematoma in two) and related to arachnoid cysts in three cases, where the most common symptoms were seizures and headache. Association between intracranial aneurysms and arachnoid cysts is a rare finding that can present with signs and symptoms related to aneurysm rupture, or with mass effect and seizures related to the cyst. The aneurysmal haemorrhage may be atypical, since it can be into the subarachnoid space, into the arachnoid cyst, or into the subdural space.

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.

Screening for brain aneurysm in the Familial Intracranial Aneurysm study: frequency and predictors of lesion detection

OBJECT

Approximately 20% of patients with an intracranial saccular aneurysm report a family history of intracranial aneurysm (IA) or subarachnoid hemorrhage. A better understanding of predictors of aneurysm detection in familial IA may allow more targeted aneurysm screening strategies.

METHODS

The Familial Intracranial Aneurysm (FIA) study is a multicenter study, in which the primary objective is to define the susceptibility genes related to the formation of IA. First-degree relatives (FDRs) of those affected with IA are offered screening with magnetic resonance (MR) angiography if they were previously unaffected, are > or = 30 years of age, and have a history of smoking and/or hypertension. Independent predictors of aneurysm detection on MR angiography were determined using the generalized estimating equation version of logistic regression.

RESULTS

Among the first 303 patients screened with MR angiography, 58 (19.1%) had at least 1 IA, including 24% of women and 11.7% of men. Ten (17.2%) of 58 affected patients had multiple aneurysms. Independent predictors of aneurysm detection included female sex (odds ratio [OR] 2.46, p = 0.001), pack-years of cigarette smoking (OR 3.24 for 20 pack-years of cigarette smoking compared with never having smoked, p < 0.001), and duration of hypertension (OR 1.26 comparing those with 10 years of hypertension to those with no hypertension, p = 0.006).

CONCLUSIONS

In the FIA study, among the affected patients' FDRs who are > 30 years of age, those who are women or who have a history of smoking or hypertension are at increased risk of suffering an IA and should be strongly considered for screening.

Distal anterior cerebral artery aneurysms: endovascular or surgical treatment? A case report

Cerebral aneurysms are occasionally associated with anomalies of the cerebral arteries. Most reports on anomalies of the anterior cerebral artery have been concerned with hypoplasia, fenestration and the infra-optic course of the A1, variant A1 perforators or Heubner's artery, multi-channeled anterior communicating artery, and azygos anterior cerebral artery. Distal anterior cerebral artery (ACA) aneurysms are known to have a poor clinical course and prognosis compared to other supratentorial aneurysms. The presence of the unpaired, distal, postcommunicating (A2) segment of the ACA is very rare in adults. We describe a patient with a ruptured aneurysm arising from the proximal end of the azygos ACA, first surgically treated with clipping and then with endovascular coiling. A 37-year-old woman at 34 weeks' gestation was transferred to our emergency room with sudden onset of severe headache and vomiting. Computed tomography (CT) revealed subarachnoid hemorrhage in the basal cisterna and the sylvian and interhemispheric fissures. Cerebral angiography showed an azygos ACA, a saccular aneurysm at the junction of the azygos ACA and the right A1 segment. A right fronto-temporal craniotomy was performed in the day of admission, and the neck of the aneurysm was clipped. One year later, an angiographic control examination revealed a regrowth of the aneurysm. The patient underwent endovascular treatment with coiling. Aneurysms of the azygos ACA are rare and their pathogenesis and course are still a matter of discussion. Developmental abnormalities or dynamic vessel wall stresses can explain the high incidence of aneurysms in these cases. The association of a rare anatomical variant with an aneurysm in the same location may suggest an embryogenesis alteration in the Willis circulation.

The role of MMP-2 and MMP-9 polymorphisms in sporadic intracranial aneurysms

Object

Matrix metalloproteinases (MMPs) are a family of endopeptidases that mediate vascular remodeling by degrading extracellular matrix components, such as collagen and elastin. On the basis of accumulating evidence that implicates increased MMP-2 (gelatinase A) and MMP-9 (gelatinase B) amounts and activity in the pathogenesis of aneurysms, the authors investigated the genetic association between polymorphisms in MMP-2 and MMP-9 and sporadic intracranial aneurysms.

Methods

Eight polymorphisms located in MMP-2 and MMP-9 were genotyped, and the association of these variations with disease was assessed in a Caucasian population consisting of 125 patients with intracranial aneurysms and 234 ethnically matched healthy volunteers.

Polymorphisms in the MMP-2 gene and the haplotypes generated from these polymorphisms were not associated with the occurrence of intracranial aneurysms. However, a polymorphism located in the 3′ untranslated region of MMP-9 showed a significant association with disease in the study population, with individuals carrying the TT genotype at increased risk for developing intracranial aneurysms (odds ratio 1.91, p = 0.005). Haplotypes containing the T allele of this polymorphism also showed a comparable association with disease. Similar results were obtained in an analysis of these polymorphisms in a subgroup of patients who presented with ruptured aneurysms.

Conclusions

The study findings support a role for MMP-9, but not MMP-2, in the pathogenesis of intracranial aneurysms.

Association of a polymorphism of the ACVRL1 gene with sporadic arteriovenous malformations of the central nervous system

OBJECT

Important central nervous system (CNS) manifestations in patients with hereditary hemorrhagic telangiectasia (HHT) include arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). Hereditary hemorrhagic telangiectasia is caused by germline mutations of two genes: ENG (HHT Type 1) and ACVRL1 (HHT Type 2). The ENG gene variations have been associated with the formation of intracranial aneurysms. The authors studied whether sequence variations in ACVRL1 or ENG are associated with the development of clinically sporadic arteriovenous dysplasias and aneurysms of the CNS.

METHODS

The coding sequence (in 44 patients with AVMs and 27 with aneurysms) and the 5' end and the polyA site (in 53 patients with AVMs) of the ACVRL1 gene were analyzed for sequence variations using direct sequencing and single-strand conformational polymorphism analysis. One ENG and three ACVRL1 gene polymorphisms were genotyped using restriction enzyme-based analysis in 101 patients with sporadic AVMs and DAVFs of the CNS, 79 patients treated for intracranial aneurysms, and 202 control volunteers. The authors identified a statistically significant association between the IVS3 -35A/T polymorphism in intron 3 of the ACVRL1 gene and the development of AVMs and DAVFs (p = 0.004; odds ratio [OR] 1.73; 95% confidence interval [CI] 1.19-2.51; after adjustments for age and sex), but not aneurysms (crude OR 0.82; 95% CI 0.55-1.18).

CONCLUSIONS

The results of this study link ACVRL1 (HHT Type 2 gene) to the formation of the clinically sporadic variants of vascular malformations of the CNS most commonly seen in patients with HHT, that is, AVMs and DAVFs.

Deficiencies in estrogen-mediated regulation of cerebrovascular homeostasis may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in menopausal and postmenopausal women

Despite the catastrophic consequence of ruptured intracranial aneurysms, very little is understood regarding their pathogenesis, and there are no reliable predictive markers for identifying at-risk individuals. Few studies have addressed the molecular pathological basis and mechanisms of intracranial aneurysm formation, growth, and rupture. The pathogenesis and rupture of cerebral aneurysms have been associated with inflammatory processes, and these have been implicated in the digestion and breakdown of vascular wall matrix. Epidemiological data indicate that the risk of cerebral aneurysm pathogenesis and rupture in women rises during and after menopause as compared to premenopausal women, and has been attributed to hormonal factors. Moreover, experimental evidence supports a role for estrogen in the modulation of each phase of the inflammatory response implicated in cerebral aneurysm pathogenesis and rupture. While the risk of aneurysm rupture in men also increases with age, this increased risk has been attributed to other recognized risk factors including cigarette smoking, use of alcohol, and history of hypertension, all of which are more common in men than women. We hypothesize, therefore, that decreases in both circulating estrogen levels and cerebrovascular estrogen receptor density may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in women during and after menopause. To test our hypothesis, experiments are needed to identify genes regulated by estrogen and to evaluate gene expression and intracellular mechanisms in cells/tissues exposed to varying concentrations and duration of treatment with estrogen, metabolites of estrogen, and selective estrogen receptor modulators (SERMs). Furthermore, it is not likely that the regulation of cerebrovascular homeostasis is due to the actions of estrogen alone, but rather the interplay of estrogen and other hormones and their associated receptor expression. The potential interactions of these hormones in the maintenance of normal cerebrovascular tone need to be elucidated. Additional studies are needed to define the role that estrogen and other sex hormones may play in the cerebrovascular circulation and the pathogenesis and rupture of cerebral aneurysms. Efforts directed at understanding the basic pathophysiological mechanisms of aneurysm pathogenesis and rupture promise to yield dividends that may have important therapeutic and clinical implications. The development of non-invasive tools such as molecular MRI for the detection of specific cells, molecular markers, and tissues may facilitate early diagnosis of initial pathophysiological changes that are undetectable by clinical examination or other diagnostic tools, and can also be used to evaluate the state of activity of cerebral aneurysm pathogenesis before, during, and after treatment.

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.

Role of apoptosis in intracranial aneurysm rupture

OBJECT

Mechanisms involved in the rupture of intracranial aneurysms remain unclear, and the literature on apoptosis in these lesions is extremely limited. The hypothesis that apoptosis may reduce aneurysm wall resistance, thus contributing to its rupture, warrants investigation. The authors in this study focused on the comparative evaluation of apoptosis in ruptured and unruptured intracranial aneurysms. Peripheral arteries in patients harboring the aneurysms and in a group of controls were also analyzed.

METHODS

Between September 1999 and February 2002, specimens from 27 intracranial aneurysms were studied. In 13 of these patients apoptosis was also evaluated in specimens of the middle meningeal artery (MMA) and the superficial temporal artery (STA). The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling technique was used to study apoptosis via optical microscopy; electron microscopy evaluation was performed as well. Apoptotic cell levels were related to patient age and sex, aneurysm volume and shape, and surgical timing. Significant differences in apoptosis were observed when comparing ruptured and unruptured aneurysms. High levels of apoptosis were found in 88% of ruptured aneurysms and in only 10% of unruptured lesions (p < 0.001). Elevated apoptosis levels were also detected in all MMA and STA specimens obtained in patients harboring ruptured aneurysms, whereas absent or very low apoptosis levels were observed in MMA and STA specimens from patients with unruptured aneurysms. A significant correlation between aneurysm shape and apoptosis was found.

CONCLUSIONS

In this series, aneurysm rupture appeared to be more related to elevated apoptosis levels than to the volume of the aneurysm sac. Data in this study could open the field to investigations clarifying the causes of aneurysm enlargement and rupture.

Multiple intracranial aneurysms. Angiographic study and endovascular treatment

SUMMARY

We evaluate endovascular treatment (EVT) as an option to deal with multiple intracranial aneurysms(MA). From 1994 to 2001, 24 patients underwent EVT for 59 MA. Patients were followed- up clinically and angiographically in a period ranging from 6 to 93 months (mean time of 22.2) and from 4 to 69 months (mean time of 19.3), respectively. Ten patients (41.6%) were treated either by EVT (n=7, 29,16%) or by mixed treatment (EVT and surgery; n=3, 12.5%). Reasons for treating just ruptured aneurysms: six (25%) had aneurysms smaller than 5 mm; three (12.5%) deaths; two (8.33%) were in the subacute period; two (8.33%) lost to follow-up; one (4.17%) authorised no procedure. No rebleeding was detected at the clinical follow-up, but there were five deaths.At immediate arteriographic control: 28 (85%) aneurysms were fully occluded, four (12%) with neck flow and one (03%) with sac flow. For 20 aneurysms followed-up: stability of occlusion was reached in seven cases (35%) and repermeabilization in 13 (65%). Management of recanalization was close arteriography in seven (54%), re-embolization in five (38%) and surgery in one (08%). When treating MA, EVT is advisable either alone or in mixed therapy. As a high degree of repermeabilization was disclosed, strict arteriographic control is required. The mechanisms underlying aneurysmal formation may be also involved in the recanalization phenomenon , a possible new manifestation of the fragility of the arterial wall.

Aneurysmal subarachnoid haemorrhage in pregnancy

Although uncommon, aneurysmal subarachnoid haemorrhage (SAH) in pregnancy can be devastating for both mother and baby. It is the leading cause of other indirect maternal death in England and Wales accounting for 60 deaths in the decade 1988-1999. No single obstetric or neurosurgical unit has sufficiently large database or experience in managing this condition in pregnancy. With significant improvements in antenatal care and management of deliveries, non-obstetric causes of maternal death such as aneurysmal subarachnoid haemorrhage are likely to become increasingly significant. The clinical features of aneurysmal subarachnoid haemorrhage closely resemble those of other commoner conditions seen in pregnancy. It is therefore imperative that awareness by obstetricians and other frontline staff is increased so that a high index of suspicion is maintained when pregnant women present with unique headaches. Prompt neurosurgical referral is vital and early involvement of an experienced neuroradiologist essential. It is only when an early diagnosis is made and an aggressive treatment instituted that the bleak case-fatality figure associated with aneurysmal subarachnoid haemorrhage in pregnancy can be improved. This review, by a multidisciplinary and multicenter team, provides a comprehensive update on the epidemiology, aetiology, clinical presentation, diagnosis and the complexities of the multidisciplinary management of this serious and potentially fatal condition when it occurs in pregnancy.

Racial Disparities in Subarachnoid Hemorrhage Mortality: Los Angeles County, California, 1985–1998

We examined the racial distribution of subarachnoid hemorrhage (SAH) mortality in a unique multiracial community. Mortality rates for SAH among the residents of Los Angeles County were calculated from death certificate data (1985-1998). Residential postal zones were classified into three strata as a measure of socioeconomic status. The number of SAH deaths was 2,897. The age-adjusted SAH mortality rate was 1.9 in whites, 2.7 in Hispanics, 3.0 in Asians and 3.7 in blacks. In those younger than 70 years of age, the SAH mortality rate among blacks was 2.2 times that of whites and 1.8 times that of Hispanics and Asians. The SAH mortality rate declines after age 70 in blacks. The SAH mortality rate was higher in women than in men in all races and it was highest in elderly Asian women (23.5 per 100,000). An inverse relationship was observed between income and SAH mortality rates in all racial groups except whites.

Multi-detector CT angiography of the intra-cranial circulation: normal anatomy and pathology with angiographic correlation

Multidetector computed tomography angiography (MD-CTA) of the intra-cranial circulation shows great potential in the evaluation of intra-cranial vascular disease. Interpreting these studies requires a detailed knowledge of the technique, its advantages and disadvantages, as well as a strong understanding of normal intra-cranial vascular anatomy. The purpose of this review is to describe the technique for MD-CTA, demonstrate normal anatomy, anatomic variants and vascular pathology with an emphasis on aneurysms.

Major risk factors for aneurysmal subarachnoid hemorrhage in the young are modifiable

BACKGROUND AND PURPOSE

To identify risk factors for subarachnoid hemorrhage (SAH) and intracerebral hemorrhage, we designed a case-control study of men and women 18 to 49 years of age (the Hemorrhagic Stroke Project [HSP]). This report focuses on SAH.

METHODS

Patients were recruited from 44 hospitals in the United States. Cases with SAH must have had a ruptured aneurysm documented by angiography or surgery. Two controls, identified by random digit dialing and matched to each patient for age, sex, race, and telephone exchange, were sought for each case subject.

RESULTS

Between 1994 and 1999, 425 patients with SAH were enrolled in HSP, and 312 cases met the criteria for aneurysmal SAH. The present analyses also included 618 matched controls. Of the 312 cases, 66% were current cigarette smokers compared with 30% of controls (adjusted odds ratio [OR], 3.73; 95% CI, 2.67 to 5.21). Cocaine use within the previous 3-day period was reported by 3% of cases and no controls (bivariate exact OR, 24.97; 95% exact CI, 3.95 to infinity; adjusted estimate not calculable). Other independent risk factors in the multivariable model included hypertension (adjusted OR, 2.21; 95% CI, 1.48 to 3.29), low body mass index (OR, 1.59; 95% CI, 1.08 to 2.35), primary family history of hemorrhagic stroke (OR, 3.83; 95% CI, 1.73 to 8.46), caffeine in pharmaceutical products (OR, 2.48; 95% CI, 1.19 to 5.20), lower educational achievement (OR, 2.36; 95% CI, 1.44 to 3.87), and nicotine in pharmaceutical products (adjusted estimate not calculable).

CONCLUSIONS

Aneurysmal SAH may be largely a preventable disease among the young and middle-aged because several prevalent risk factors can be modified by medication (eg, hypertension) or behavioral change (eg, cigarette smoking, cocaine use). The association of caffeine and nicotine in pharmaceutical products and aneurysmal SAH warrants further study.

Recurrent torticollis caused by dissecting vertebral artery aneurysm in a pediatric patient: results of endovascular treatment by use of coil embolization: case report

OBJECTIVE AND IMPORTANCE

Torticollis is a symptom that can be related to different pathological mechanisms ranging from simple to life-threatening conditions. We report a child with recurrent torticollis caused by an intracranial dissecting vertebral artery aneurysm. This is a very rare condition in childhood, and it was resolved successfully with endovascular treatment.

CLINICAL PRESENTATION

The patient was a 10-year-old boy with a 4-year history of left recurrent torticollis, followed by hemiparesis, dysarthria, dysmetria, and tremor. Brain magnetic resonance imaging and digital angiography detected a dissecting aneurysm involving the fourth segment of the left vertebral artery.

INTERVENTION

The patient underwent endovascular treatment. Coil embolization, followed by histoacryl injection into the lesion, provided complete obliteration of the aneurysmal sac.

CONCLUSION

The patient's postoperative course was characterized by a dramatic disappearance of symptoms and signs within a few hours of the intervention. No relapses of symptoms occurred during a follow-up period of 18 months. This is the first report of a child in whom recurrent torticollis was related to a dissecting vertebral artery aneurysm. Although long-term results of vertebral artery coil embolization remain to be elucidated, the method seems reliable and effective in treatment of these vascular lesions in pediatric patients.

A 10-year-old boy with Marfan syndrome exhibiting cerebrovascular abnormalities

A young male with Marfan syndrome, diagnosed at the age of 10 years, presented with conspicuous elongation and tortuosity of the internal carotid, middle cerebral, vertebral and basilar arteries on cranial magnetic resonance and computed tomography angiography. There is a little mention of cerebral blood vessel examinations in the guidelines of the American Academy of Pediatrics for Marfan syndrome. Guidelines may be provided for the evaluation of cerebrovascular system for the patients with Marfan syndrome who have family history of Marfan syndrome as well as a family history of death from subarachnoid hemorrhage.

Molecular anatomy of an intracranial aneurysm: coordinated expression of genes involved in wound healing and tissue remodeling

BACKGROUND AND PURPOSE

Approximately 6% of human beings harbor an unruptured intracranial aneurysm. Each year in the United States, >30 000 people suffer a ruptured intracranial aneurysm, resulting in subarachnoid hemorrhage. Despite the high incidence and catastrophic consequences of a ruptured intracranial aneurysm and the fact that there is considerable evidence that predisposition to intracranial aneurysm has a strong genetic component, very little is understood with regard to the pathology and pathogenesis of this disease.

METHODS

To begin characterizing the molecular pathology of intracranial aneurysm, we used a global gene expression analysis approach (SAGE-Lite) in combination with a novel data-mining approach to perform a high-resolution transcript analysis of a single intracranial aneurysm, obtained from a 3-year-old girl.

RESULTS

SAGE-Lite provides a detailed molecular snapshot of a single intracranial aneurysm. These data suggest that, at least in this specific case, aneurysmal dilation results in a highly dynamic cellular environment in which extensive wound healing and tissue/extracellular matrix remodeling are taking place. Specifically, we observed significant overexpression of genes encoding extracellular matrix components (eg, COL3A1, COL1A1, COL1A2, COL6A1, COL6A2, elastin) and genes involved in extracellular matrix turnover (TIMP-3, OSF-2), cell adhesion and antiadhesion (SPARC, hevin), cytokinesis (PNUTL2), and cell migration (tetraspanin-5).

CONCLUSIONS

Although these are preliminary data, representing analysis of only one individual, we present a unique first insight into the molecular basis of aneurysmal disease and define numerous candidate markers for future biochemical, physiological, and genetic studies of intracranial aneurysm. Products of these genes will be the focus of future studies in wider sample sets.

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.

Functional polymorphism in the matrix metalloproteinase-9 promoter as a potential risk factor for intracranial aneurysm

BACKGROUND AND PURPOSE

There is convincing evidence that susceptibility to intracranial aneurysms (ICAs) has a genetic component. However, few studies have sought to identify functional variation in specific candidate genes that may predispose individuals to develop an ICA.

METHODS

ICA cases and controls were genotyped for a simple length polymorphism in the promoter of matrix metalloproteinase-9 (MMP-9) to test for association between variation in the promoter and the occurrence of ICA. Alternative alleles were cloned into an in vitro reporter vector, transfected into human HT1080 fibroblasts, and assayed for promoter activity by beta-gal and luciferase assays. Electrophoretic gel shift assays were used to assess nuclear factor binding.

RESULTS

A length polymorphism in the promoter of MMP-9 was nonrandomly associated with the occurrence of ICA in a case-control study. This polymorphism was shown, by direct sequencing of 36 individuals, to be the only sequence variation within a 736-base pair region proximal to the transcriptional start site of the gene. Variation in the length of this repetitive element was shown to modulate promoter activity in an in vitro reporter assay, with the highest promoter activity being observed in constructs bearing the longest [(CA)23] element. Electrophoretic mobility shift assays were used to show that the (CA) element is bound by a sequence-specific DNA-binding protein.

CONCLUSIONS

Genetic variation in the promoter of the MMP-9 gene results in variation in its expression at the level of transcription. This may result in subtle differences in MMP-9 activity within the circle of Willis, leading to increased susceptibility to ICA formation.

Screening for intracranial aneurysms in patients with isolated polycystic liver disease

OBJECT

Isolated polycystic liver disease, that is, polycystic liver disease without kidney cysts, is an entity distinct from polycystic kidney disease. It is not known whether patients with isolated polycystic liver disease are at an increased risk for developing intracranial aneurysms, similar to patients with polycystic kidney disease. The authors screened individuals for intracranial aneurysms in a family in which isolated polycystic liver disease occurred to study the relationship between these two disorders.

METHODS

Six siblings requested screening for intracranial aneurysms. Their father had died of a middle cerebral artery aneurysm. Isolated polycystic liver disease was found at autopsy. Their paternal aunt had died of a basilar artery aneurysm, but no autopsy had been performed in that case. Screening with magnetic resonance (MR) angiography and subsequent conventional angiography showed a 5-mm posterior communicating artery aneurysm in one sibling in whom abdominal ultrasound examination yielded normal findings and a posterior communicating artery infundibulum in another sibling in whom an ultrasound examination detected isolated polycystic liver disease. Screening did not detect aneurysms or polycystic liver disease in the other siblings. Thus, of the two patients with isolated polycystic liver disease in this family, one had a ruptured aneurysm and the other had an infundibulum.

CONCLUSIONS

Findings in this family suggest an association between isolated polycystic liver disease and intracranial aneurysms. However, because of the delay in onset of the appearance of liver cysts in individuals who carry the disease gene, abdominal ultrasonography is not a useful method to exclude those family members at risk for aneurysm development.