An abnormal widening or ballooning of a portion of a blood vessel. The blood vessel wall becomes weaker in this location. Aneurysms can occur in any artery in the body.

Some common locations for aneurysms include:

• Abdominal aortic aneurysm
• Thoracic aortic aneurysm
• Cerebral aneurysm
• Popliteal artery (leg) aneurysm
• Mesenteric artery (intestine) aneurysm
• Splenic artery aneurysm

Aneurysms are either congenital or acquired. It is not clear exactly what causes aneurysms. In certain cases (abdominal aortic aneurysms), hypertension is thought to be a contributing factor.

Atherosclerotic disease (cholesterol buildup in arteries) may contribute to the formation of certain types of aneurysms. Pregnancy is often associated with the formation and/or rupture of splenic artery aneurysms.

Swelling with a pulsatile (throbbing) mass at the site of the aneurysm are often seen.

In the case of rupture, hypotension (low blood pressure), high heart rate, and lightheadedness are seen. The risk of death from rupture is high.

Physical exam, ultrasound examination, and CT scan are used to evaluate aneurysms.

Surgical excision is generally recommended. The timing and indications for surgery differ depending on the type of aneurysm.

With successful surgical repair, the prognosis is excellent.

The main complications of aneurysm include rupture, infection and compression of local structures. Rupture of the aneurysm, with massive bleeding, which is often fatal-this is seen with abdominal aortic aneurysms, mesenteric artery aneurysms, and splenic artery aneurysms.

Infection of the aneurysm, which sometimes follows infection at other sites of the body, can lead to systemic illness and rupture. Thrombosis of the aneurysm occurs when blood clots inside the aneurysm, blocking further blood flow past the site of the aneurysm and depriving tissues of blood supply.

In certain cases, aneurysms can compress neighboring structures such as nerves, leading to neurologic deficits such as weakness and numbness. This can occur with popliteal artery aneurysms.

Call your physician for any new mass, whether or not it is pulsatile.

Control of high blood pressure may help prevent some aneurysms. Control of all risk factors associated with atherosclerotic disease (diet exercise, cholesterol control) may help prevent aneurysms or their complications.