Definition of a Brain Aneurysm

Brain aneurysms are a frightening health risk. It has been estimated that 1 in 15 Americans will develop an aneurysm in their lifetime. A brain aneurysm produces very few symptoms until it becomes a serious problem. Aneurysms usually lead to brain damage and often death. Because they are so serious, it is important to understand what an aneurysm is and to understand their causes and effects.

What Is a Brain Aneurysm?

• Brainaneurysm.com defines a brain aneurysm as "...an abnormal bulging outward of one of the arteries in the brain." These bulges form when the artery walls weaken. Aneurysms occur most commonly in arteries in the brain and in the main artery of the heart, called the aorta. If left untreated, an aneurysm can burst, causing massive internal bleeding, brain damage and even death.

How Aneurysms Form

• An aneurysm starts small. It begins as a small bulge in the blood vessel that is hardly noticeable in X-rays. The afflicted person is unaware that he is developing an aneurysm. There is no pain or suffering associated with a small aneurysm. Sometimes, an aneurysm can stay small for long periods of time without growing. As time passes, more and more blood collects in the vessel, causing it to grow larger and larger until it bursts. This will cause massive internal bleeding.

Where Do Brain Aneurysms Form?

• The most common place for a brain aneurysm to form is at the base of the brain, called the Circle of Willis, which is the main system of arteries that supplies blood to the brain. It has been estimated that 85 percent of brain aneurysms form here. Other common locations include the anterior cerebral artery, the internal carotid, the posterior communicating artery and the middle cerebral artery.

Effects of an Aneurysm

• An aneurysm can often stay small for years. These small aneurysms are harmless and produce no symptoms or side effects. According to the Mayo Clinic, "Most brain aneurysms, however, don't rupture, create health problems or cause symptoms. Such aneurysms are often detected during tests for other conditions. Treatment for an unruptured brain aneurysm may be appropriate in some cases and may prevent a rupture in the future." However, many aneurysms will continue to grow and many will burst. Just before it bursts, the afflicted person may experience an extremely severe headache, nausea, vision loss, vomiting and unconsciousness. Sometimes the person feels no symptoms until the aneurysm bursts. The burst aneurysm usually comes on quickly and surprises an apparently healthy person. The blood loss in an aneurysm can be severe, and will usually lead to brain damage and death.

Aneurysm Causes

• Genetics plays a part in the development of an aneurysm. It has been estimated that 20 percent of people with a burst or bleeding aneurysm had a close relative who suffered from the same condition. However, there is some uncertainty as to the exact role of genetics with regard to aneurysms. Though an obvious family link has been noted, a pattern has not been detected. Two or three people in a family may suffer from aneurysms, but the genetic links between these family members are often indirect. Many diseases have been linked to aneurysms, including polycystic kidney disease, Ehlers-Danos Syndrome, Marfan Syndrome, and Neurofibromatosis.