An aneurysm (or aneurism) is a localized, blood-filled dilation (bulge) of a blood vessel caused by disease or weakening of the vessel wall. Aneurysms most commonly occur in arteries at the base of the brain (the circle of Willis) and in the aorta (the main artery coming out of the heart), a so-called aortic aneurysm. The bulge in a blood vessel can burst and lead to death at any time. The larger an aneurysm becomes, the more likely it is to burst. Aneurysms can usually be treated.
Aneurysms may involve arteries or veins and have various causes. They are commonly further classified by shape, structure and location.
Most frequent site of occurrence is in the anterior cerebral artery from the circle of Willis. The occurrence and expansion of an aneurysm in a given segment of the arterial tree involves local hemodynamic factors and factors intrinsic to the arterial segment itself.
Control of high blood pressure may help prevent some aneurysms. Following a healthy diet, getting regular exercise, and keeping your cholesterol at a healthy level may also help prevent aneurysms or their complications. Do not smoke. If you do, quitting will lower your risk of an aneurysm.