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