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Ebook Handbook of cerebrovascular disease and neurointerventional technique: Part 2

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Part 2 book “Handbook of cerebrovascular disease and neurointerventional technique” has contents: Intracranial aneurysms and subarachnoid hemorrhage, arteriovenous malformations, dural arteriovenous fistulas, cavernous malformations and venous angiomas, extracranial cerebrovascular occlusive disease, and other contents. | 13. Intracranial Aneurysms and Subarachnoid Hemorrhage An aneurysm is an abnormal dilatation of an artery. In layman’s terms, an aneurysm can be thought of as a weak spot in the wall of an artery, similar to a garden hose that has been filed down on one side; water under pressure inside the hose will make the weak spot bulge out. Intracranial aneurysms can be broadly classified as saccular, fusiform, or dissecting. 13.1. Intracranial aneurysms: Pathophysiology 13.1.1. Pathology of intracranial aneurysms An aneurysm is, by definition, an arterial structure. Most saccular aneurysms share a common morphology.1-3 1. Mechanism of formation. Intracranial aneurysms appear to result from a complex series of factors including hemodynamic stress, sustained abnormal vascular remodeling, and inflammation.4,5 2. Saccular aneurysms are typically found at arterial branch points, where there is a gap in the media, although a significant percentage of aneurysms are not clearly associated with a branching vessel. 3. Gross anatomy: (a) Unruptured aneurysms may appear uniformly pink, like adjacent arteries, or they may have red areas, representing nearly translucent regions of the aneurysm dome, through which blood can be seen. Aneurysms may also have thick, atheromatous areas as well. (b) Ruptured aneurysms. Aneurysms typically rupture at the apex of the dome; a dense fibrin cap is usually found in this region during surgery. (c) Morphological features: ● Multiple lobes. Some 9% of unruptured aneurysms and 40% of ruptured aneurysms are multilobular.6 ● Daughter sac. A daughter sac was found in 57% of ruptured aneurysms and 16% of unruptured aneurysms.7 Also sometimes referred to as “Murphy’s tit.” (d) Site distribution (unruptured aneurysms in patients with no prior history of SAH).8 ● Cavernous carotid artery, 16.9%. ● ICA, 24.8%. ● Anterior communicating or ACA, 10.0%. ● MCA, 22.7%. ● Posterior communicating artery, 13.9%. ● Vertebrobasilar or PCA, 6.6%. ● Basilar artery apex,