Aneurysm

An aneurysm occurs when part of an artery swells. It is caused by a damaged blood vessel or a weakness in the blood vessel wall. The pressure of blood in the artery causes it to 'balloon' out at the weak point. The swelling can be small and spherical (berry-sized), normally occurring near blood vessel branches, or it can be larger and balloon-like. Large aneurysms may also extend along the arteries.

Aneurysms can occur anywhere in the body, but they are most common on the wall of the aorta, the largest artery in the body. The aorta extends from the left side of the heart, down through the chest and into the abdomen. It then divides into two branches, known as the iliac arteries. Brain aneurysms, also known as cerebral aneurysms, can occur anywhere in the brain.

Aneurysms can affect people of any age and both sexes. However, they are most common in men, people with high blood pressure (hypertension) and those over the age of 65. Cerebral aneurysms can also occur as a result of a congenital malformation (birth defect). If they burst, aneurysms can be fatal.

The symptoms of an aneurysm depend on its size, its growth rate and where it is located. A small, unchanging aneurysm will often produce no symptoms and may go unnoticed.

Large brain aneurysms can press on nerve tissue causing a loss of feeling in the face or problems with the eyes.

Immediately before a brain aneurysm ruptures, the symptoms are:

• a sudden and severe headache,
• nausea,
• vision impairment,
• vomiting,
• loss of consciousness, and
• fits or seizures.

If it ruptures, it will cause bleeding in the brain and a haemorrhagic stroke. Blood can also leak into the area surrounding the brain, causing a blood clot within the skull (intracranial haematoma).

Most aortic aneurysms occur in the abdominal aorta, below the diaphragm (the thin membrane separating the chest from the abdomen). Many people have this type of aneurysm for years before they notice any symptoms. Symptoms vary depending on the type and location of the aneurysm, but can include:

• a pulsating feeling in the abdomen,
• back pain, and
• abdominal pain (that may also spread towards the back).

Aortic aneurysms are often discovered by a GP while carrying out a routine examination of the abdomen. After carefully feeling your abdomen, your GP may find a lump, high up and a little to the right, that pulses with your heartbeat.

If an aortic aneurysm continues to increase in size, it may press on the spine and chest organs. This can cause pain, coughing, loss of voice and difficulty in swallowing and breathing.

In most cases, brain aneurysms are caused by a weakness in the artery wall that has been present from birth. However, they may also be linked to high blood pressure and arteriosclerosis, which is the formation of plaques of cholesterol, platelets, fibrin and other substances on the arterial walls.

Aneurysms that occur in larger arteries, such as the aorta, are usually due to the build-up of fatty deposits (cholesterol) on the artery walls (this is known as atherosclerosis). Anyone can develop atherosclerosis, but it is more common with increasing age. Certain 'risk factors' also increase the chance of atherosclerosis developing. These include; smoking, high blood pressure, diabetes, a raised cholesterol level, lack of exercise and obesity.

The genetic disease, Marfan syndrome, is another much less common cause of an aortic aneurysm.

Your GP may be able to feel the bulge of an aortic aneurysm during a routine examination of the abdomen.

An ultrasound scan is often used to diagnose an aortic aneurysm and usually gives a clear picture of its size. Size is an important factor when deciding on a course of treatment. Ultrasound is a safe, painless and non-invasive test.

A brain aneurysm can be detected using a special kind of X-ray called an angiogram or arteriogram. To highlight the aneurysm, a dye is injected into the bloodstream. The blood in the vessels shows up on the film as white columns. If an artery is swollen, the dye in the blood will pass into it and the X-ray will show the swelling.

A CAT scan may be used to find out if the aneurysm is affecting any of the arteries that come off the aorta. For instance, if the aneurysm involves the arteries to the kidneys, this can be detected and the information gained will be used by surgeons if they decide to operate.

Treatment of aneurysms depends on where they are located and how big they are. Not all aneurysms are treated at the time they are diagnosed. Surgery is sometimes carried out to prevent an aneurysm rupturing or, in the case of a brain aneurysm which has already ruptured, to stop the bleeding and reduce the risk of permanent brain damage.

Aortic aneurysms

Surgery to repair an aortic aneurysm is a major operation and it is not usually recommended unless the aneurysm is large (bigger than 55mm wide). The surgical procedure involves replacing the part of the aorta affected by the aneurysm with a synthetic graft. This is a tube made out of an elastic material that is very similar to a normal healthy aorta.

For small aortic aneurysms (less than 55mm wide) the risk of death from surgery is usually higher than the risk of the aneurysm rupturing. However, you must continue to have regular medical check ups to make sure the aneurysm is not growing.

Brain aneurysms

If you have a brain aneurysm, you will see a specialist to discuss the treatment options that are available to you. If it is decided that surgery is the best course of treatment, a surgical procedure called a craniotomy will be carried out to open the head.

Surgical clipping

The aneurysm is found using a microscope and a metal clip is used to clip the neck of the aneurysm. This seals it off without damaging the main artery. The aneurysm is packed with a special type of glue to encourage the blood to clot and strong tissue to form. To stop the clot dissolving and to prevent re-bleeding, antifibrinolytic drugs may be prescribed.

If a brain aneurysm ruptures, blood flows into the space surrounding the brain (known as the subarachnoid space) and this can result in a subarachnoid haemorrhage.

Following aneurysm surgery, you will usually be kept in intensive care or a specialist ward for one to two weeks to monitor your progress. It is important to avoid any strain or exertion. You will be given medicines to keep your blood pressure low. A drip will be used to make sure you get all the fluids you need.

Coil embolisation

Coil embolisation is a relatively new method of treating brain aneurysms. The advantage of coil embolisation is that, unlike surgical clipping, there is no need to open the skull.

During a coil embolisation, the surgeon will insert a small tube into a main artery, usually in the groin. The tube is guided up to the site of the aneurysm using a special X-ray scanner. A metal coil is then passed through the tube which encourages the blood to clot inside the aneurysm.

Coil embolisation is a specialised technique which is usually only available at specialist units. Therefore, you may have to travel away from your local area in order to receive treatment.

With aneurysms, rupture (bursting) is a major problem. Before an abdominal aneurysm ruptures, you are likely to experience excruciating pain in your lower abdomen and back. If an abdominal aneurysm ruptures, it will cause mass bleeding leading to shock and possibly death.

If a cerebral aneurysm bursts, it will cause serious bleeding into the fluid surrounding the brain. This is called a subarachnoid haemorrhage and causes a severe headache, usually followed by a rapid loss of consciousness. Symptoms may include; neck stiffness, vomiting, weakness or paralysis of various parts of the body and possibly death.

Sometimes a piece of a clot, within an aneurysm can come loose and can travel out into the arterial system. This clot fragment is known as a thrombosis and if it lodges in a smaller artery, it will block the flow of blood. A thrombosis can be very serious if it causes a blockage in an artery to a major organ, such as in the brain, heart or lungs.

Many aneurysms are the result of arteriosclerosis. Arteriosclerosis is a vascular disease that is caused by the build up of plaques, such as cholesterol, platelets and fibrin, on the artery walls. You can prevent an aneurysm from expanding and rupturing by taking the following steps to prevent arteriosclerosis:

• stopping smoking,
• controlling high blood pressure,
• lowering high blood cholesterol, and
• eating a healthy, balanced diet with plenty of fruit and vegetables.

Your GP may prescribe medications to lower your blood pressure and slow the growth of your aneurysm. Your GP may also monitor the size of your aneurysm using an ultrasound or CAT scan every 6-12 months.