Elsevier

Neurochirurgie

Volume 61, Issue 6, December 2015, Pages 361-365
Neurochirurgie

Round table: Giant intracranial aneurysms
Epidemiology, genetic, natural history and clinical presentation of giant cerebral aneurysmsÉpidémiologie, génétique, histoire naturelle, physiopathologie et présentation clinique des anévrismes géants

https://doi.org/10.1016/j.neuchi.2015.08.003Get rights and content

Abstract

Giant cerebral aneurysms represent 5% of intracranial aneurysms, and become symptomatic between 40 and 70 years with a female predominance. In the paediatric population, the giant aneurysm rate is higher than in the adult population. Classified as saccular, fusiform and serpentine, the natural history of giant cerebral aneurysms is characterized by thrombosis, growth and rupture. The pathogenesis of these giant aneurysms is influenced by a number of risk factors, including genetic variables. Genome-wide association studies have identified some chromosomes highlighting candidate genes. Although these giant aneurysms can occur at the same locations as their smaller counterparts, a predilection for the cavernous location has been observed. Giant aneurysms present with symptoms caused by a mass effect depending on their location or by rupture; ischemic manifestations rarely reveal the aneurysm. If the initial clinical descriptions have been back up by imagery, the clinical context with a pertinent analysis of the risk factors remain the cornerstone for the management decisions of these lesions. Five year cumulative rupture rates for patients with giant aneurysm were 40% for those located on the anterior part of circle of Willis and 50% for those on the posterior part. The poor outcome of untreated patients justifies the therapeutic risks.

Résumé

Les anévrismes géants représentent 5 % de l’ensemble des anévrismes intracrâniens et deviennent symptomatiques entre 40 et 70 ans, avec une prépondérance féminine. Dans la population pédiatrique, la fréquence des anévrismes géants est plus élevée que chez l’adulte. L’évolution de ces anévrismes est influencée par un certain nombre de facteurs de risque, en particulier génétiques. L’histoire naturelle de ces anévrismes comprend 3 types de phénomènes : thrombose, accroissement et rupture. Ils sont classés en sacculaire, fusiforme et serpentin. Bien qu’ils se localisent aux mêmes endroits que les anévrismes classiques, les localisations intra-caverneuse et carotidienne proximale prédominent nettement. Les anévrismes géants s’expriment soit en raison de leur effet de masse, soit d’une rupture, les manifestations ischémiques étant beaucoup plus rares. Si les premières descriptions cliniques ont été dépassées par l’imagerie, le contexte clinique avec l’analyse des facteurs de risque restent essentiels pour la prise de décision thérapeutique. Le risque de rupture à 5 ans pour les patients sans antécédents d’hémorragie sous-arachnoïdienne est de 40 % pour les anévrismes de la circulation antérieure, de 50 % pour ceux de la circulation postérieure et de 6 % pour les anévrismes caverneux. Le mauvais pronostic des patients non traités justifie une prise de risque thérapeutique.

Introduction

Giant cerebral aneurysms, defined by a diameter above 25 mm, are often discovered through their mass effect or haemorrhage. If the initial clinical descriptions have been back up by imagery, the clinical context with a pertinent analysis of the risk factors remain the cornerstone for the management decisions for these lesions. The knowledge of the natural history as well as the evolutionary modalities of these aneurysms is critical in making treatment decisions.

In this chapter, epidemiologic, genetic, physiopathology, clinical and natural history of these giant aneurysms will be described, taking in account our multicentre studies and the data reported in the literature.

Section snippets

Epidemiology

The prevalence of intracranial aneurysms is estimated to be approximately 2% [1]. The aneurysm is unique (70–75%) or multiple (25–30%) [2]. The risk factors concerning the formation, growth or the rupture of aneurysms include age, sex, smoking, high blood pressure, hypercholesterolemia and atherosclerosis in general [3]. Familial aneurysms may have a larger size at rupture, and are often multiple, which suggests a genetic implication [4].

Giant cerebral aneurysms represent approximately 5% of

Genetics

The pathogenesis of intracranial aneurysms are influenced by a number of risk factors, including genetic variables as proven by higher frequency of aneurysms in some hereditary diseases, including polycystic kidney disease and familial aggregation [20]. Familial aneurysms account for 7 to 20% of patients with cerebral aneurysms [21], [22], 5.1% in our population of giant aneurysms [23]. In fact, some diseases are genetically related to cerebral aneurysms, with a majority involving connective

Physiopathology

Three types of pathological event feature in the natural history of giant aneurysms: spontaneous thrombosis, progressive growth responsible for mass effect and rupture. Giant aneurysms are classified as saccular, fusiform and serpentine.

Natural history

In the general population of all unruptured and untreated aneurysms, one third showed a gradual growth after a follow-up of 21 months [33].

The literature emphasizes the pejorative aspect of the natural history of giant aneurysms with a high mortality rate. Drake et al., in a personal retrospective cohort of 31 patients with non-treated giant aneurysms, reported a 66% mortality after 2 years, and 80% after 5 years [37]. If the aneurysms are located on the posterior circulation, mortality reaches

Clinical presentation

If giant aneurysms have the same location as the others, there is a clear predominance on the internal carotid artery, in its intracavernous and ophthalmic portions [5]. The diagnostic circumstances of giant aneurysms are most often a pseudotumoral syndrome, followed by the rupture responsible for subarachnoid or intracerebral haemorrhage. Other symptoms may exist, such as headaches, ischemic stroke, or seizures. Whatever the topography, headaches alone or in association to other symptoms are

Conclusion

The clinical presentation of giant aneurysms is different from other aneurysms, due to the high rate of pseudotumoral syndrome (mass effect). The risk of rupture increases with the size of the aneurysm, and is highest for giant aneurysms whatever the location.

From the natural history of these anomalies, one must emphasize the severity of their evolution if untreated, what justifies even risky therapeutic. As these aneurysms are seldomly encountered by a sole team, the decision must be tailored

Disclosure of interest

The authors declare that they have no competing interest.

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