What is an aneurysm? An aneurysm is an abnormal widening or ballooning of an artery due to weakness in the wall of the blood vessel. Aneurysms are dangerous because they may burst, spilling blood in the area surrounding the blood vessel. The disease can occur in the aorta, in a blood vessel in the brain, or in a peripheral blood vessel. An aneurysm can occur in any artery in the body but commonly occurs in the aorta, the largest artery in the body, which leads from the heart into the abdomen. Aortic aneurysms are most commonly found in the abdominal cavity (known as abdominal aortic aneurysms) but may also occur in the chest or thoracic cavity, where they are known as thoracic aortic aneurysms. Most commonly, people who develop aortic aneurysms are Caucasian, male, older than 60 years, and have high blood pressure, atherosclerosis, or a family history of aneurysm. Cigarette smoking is also a known risk factor for the development of aortic aneurysm. Abdominal aortic aneurysms are estimated to occur in 1.3% of men aged 45 to 54 years of age and 12.5% of men between 75 and 84 years of age in the United States (Source: CDC). Brain aneurysms are estimated to occur in approximately 30,000 people in the United States (Source: AANS). Peripheral artery aneurysms most commonly occur in the popliteal artery (behind the knees), the mesenteric artery (intestine), femoral artery (groin) and splenic artery (spleen). The signs and symptoms of an aneurysm depend on its location. The disease course varies among individuals. Some people with an aneurysm have no symptoms at all, but if the aneurysm ruptures, internal bleeding occurs, potentially causing pain, low blood pressure, a rapid heartbeat, and lightheadedness. When an aneurysm bursts inside the skull (intracranial aneurysm), individuals report ”the worst headache of their life” followed by rapidly progressive rapid decline in alertness, mental function, and other neurologic functions. If the aneurysm occurs near the surface of the skin, pain and swelling with a throbbing mass are often felt. Fortunately, aneurysms can be treated successfully with a range of options such as lifestyle changes, high blood pressure management, or surgery. Left untreated, an aneurysm may rupture. Rupture of an artery can result in life-threatening bleeding. Seek immediate medical care (call 911) if you, or someone you are with, have symptoms of a ruptured aneurysm, such as severe back pain, sudden severe headache, rapid heart rate, difficulty swallowing, blurred vision, cold skin, or loss of consciousness.