**1. Introduction**

42 Aneurysm

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Intracranial saccular aneurysms are lesions of the arteries, the etiology of which remains controversial. Some evidence indicates that intracranial saccular aneurysms arise from a congenital deficiency of the smooth muscle of the arterial wall and local hemodynamic disorders particularly in areas of arterial bifurcation [1], [2]. These aneurysms are less commonly due to trauma, tumors, infections, use of drugs, and conditions associated with high arterial flow {e.g., arteriovenous malformations (AVM)} and connective tissue diseases [3-11]. Saccular aneurysms might be single or multiple and are mostly located in the Circle of Willis. These aneurysms are the most frequent cause of spontaneous subarachnoid hemorrhage (SAH) and primarily affect females. Patients become symptomatic after rupture, which usually occurs between ages 40 to 60 years old[12]. Because rupture is associated with high morbidity and mortality rates, appropriate treatment must be performed as soon as possible. The aim of the treatment is to exclude the aneurysm from the circulation to avoid further bleeding, while preserving the parent artery [13, 14]. Currently, two techniques are available for the treatment of saccular aneurysms: 1) microsurgery (developed by Yasargil), which is based on the placement of a metallic clip in the aneurysm neck [15], and 2) endovascular coiling (developed by Guglielmi), which is based on the introduction of platinum microcoils inside the aneurysms that induce thrombosis and thus isolate aneurysms from the circulation[16]. The continuous development of this latter technique has reduced the morbidity and mortality of the treatment of brain aneurysms [17]; however, improvement of models of experimental saccular aneurysms is needed to develop novel embolization techniques and to test new materials.

© 2012 de Oliveira, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
