Aneurysm

What is an aneurysm?

An aneurysm is when a weakened area in an artery wall bulges outwards. Many aneurysms are harmless and do not cause any symptoms, but if an aneurysm bursts (ruptures) it is a medical emergency and can be fatal.

Types of aneurysms

Aneurysms are classified according to the blood vessels in which they occur or the part of the body that they affect. The most common types of aneurysms are aortic aneurysms which affect the aorta (the largest blood vessel in the body) and cerebral aneurysms which affect the arteries that supply the brain.

Types of aneurysms include:

• abdominal aortic aneurysm (AAA) - occurs in the part of your aorta that supplies your abdomen with blood. Abdominal aortic aneurysms are six times more common in men than women
• thoracic aortic aneurysm - this type of aortic aneurysm is less common than an abdominal aortic aneurysm (AAA) and develops in the top part of your aorta, in your chest cavity (thorax)
• cerebral aneurysm (brain aneurysm) - occurs in an artery that supplies your brain. The most common type of cerebral aneurysm is a saccular (berry) aneurysm, a round blood-filled sac that bulges from the artery and resembles a berry. Brain aneurysms are more common in women
• mesenteric artery aneurysm - occurs in the mesenteric artery that supplies your intestines
• carotid aneurysm - this rare type of aneurysm forms in your carotid arteries that supply blood to your brain, neck, and face
• splenic artery aneurysm - affects the arteries that supply your spleen
• popliteal aneurysm - occurs in the popliteal artery that runs behind your knees
• common iliac aneurysm - an aneurysm in one of the iliac arteries that branch off the abdominal aorta into the pelvic area

What causes aneurysms?

It isn't always clear what causes an aneurysm to develop. Sometimes a weakness in an artery wall may be present at birth, while in other cases it develops later in life due to aortic injury or disease. 

A condition called atherosclerosis appears to be a significant cause of aneurysms as the heart has to pump harder to push blood past fatty deposits in your arteries leading to increased pressure and damage to the artery wall.

What are the risk factors for aneurysm?

Some risk factors for developing an aneurysm include:

• age
• high levels of fats in the blood (hyperlipidaemia)
• high blood pressure (hypertension)
• diabetes
• genetic factors
• family history of aneurysm
• smoking
• obesity

What are the symptoms of an aneurysm?

Aneurysms often don't have any symptoms until they leak or rupture. A ruptured aneurysm is a medical emergency and can be fatal if not treated quickly.

Unruptured aneurysms can sometimes cause symptoms if they block the circulation to other tissues. They may also cause blood clots that can lead to a stroke or other serious complications.

Fast-growing abdominal aortic aneurysms (AAA) can sometimes cause symptoms before they rupture. These symptoms can include abdominal pain, lower back pain, or a pulsating sensation in the abdomen.

Thoracic aortic aneurysms can affect the nearby nerves and blood vessels, causing symptoms such as difficulty swallowing, breathing difficulties, and pain in the chest, jaw, and upper back.

Symptoms of an unruptured splenic aneurysm may include a pulsating sensation and pain in the upper left part of your abdomen (pain may radiate to your left shoulder).

Symptoms of a ruptured aneurysm

The symptoms of a ruptured aneurysm depend on the type of aneurysm and where it is in your body. You may be able to feel (palpate) an aneurysm (like a pulsating lump) if it is close to the surface of your body. It may also be painful and appear swollen.

An aneurysm may rupture in one go, or two stages. If it ruptures in two stages, symptoms will start suddenly and then ease for a short time before your body goes into shock. If you experience symptoms of a ruptured aneurysm, seek immediate medical attention even if your symptoms improve.

Abdominal aortic aneurysm (AAA)

Symptoms of a ruptured abdominal aortic aneurysm may include:

• sudden and severe pain in your abdomen or lower bac
• sudden and significant drop in blood pressure
• feeling dizzy or lightheaded
• shortness of breath
• fast heart rate
• breaking out in a cold sweat

Thoracic aortic aneurysm

Symptoms of a ruptured thoracic aortic aneurysm may include:

• sudden and severe pain in your chest and/or back
• sudden and significant drop in blood pressure
• numbness in your arms and legs

Cerebral aneurysm

Symptoms of a ruptured cerebral aneurysm may include:

• sudden, excruciating headache (known as a ‘thunderclap headache’)
• nausea and vomiting
• changes in your vision such as double vision
• pain when looking at light
• loss of consciousness

Mesenteric artery aneurysm

Symptoms of a ruptured mesenteric artery aneurysm may include:

• sudden, intense, continuous abdominal or back pain that may radiate to your legs
• rapid heart rate
• excessive sweating and clamminess
• feeling dizzy or lightheaded
• nausea and vomiting
• a sudden, significant drop in blood pressure

Common Iliac aneurysm

Symptoms of a ruptured common iliac aneurysm may include:

• a sudden, sharp, ripping feeling in the groin 
• sudden pain in the lower abdominal, lower back, groin and/or thigh 
• a sudden, significant drop in blood pressure

Popliteal aneurysm

Symptoms of a ruptured popliteal aneurysm may include:

• swelling, pain or bruising in your leg, groin or behind your knee 
• palpable (easily felt) pulse in your groin or behind your knee
• difficulty moving your affected leg
• numbness
• your skin may feel cold to the touch

Splenic artery aneurysm

Symptoms of a ruptured splenic aneurysm may include:

• nausea and vomiting
• sudden, severe pain in your upper abdomen, just beneath your ribs
• pain in your left shoulder
• a sudden, significant drop in blood pressure
• rapid heart rate

Carotid aneurysm

Carotid aneurysms rarely rupture but may interrupt blood flow to your brain leading to a mini-stroke (transient ischemic attack or TIA) or stroke.

Both TIAs and strokes are medical emergencies that need immediate treatment. Call an ambulance or go straight to A&E if you have symptoms of a TIA or stroke, including:

• sudden, severe headache
• numbness or weakness in your face, arms, or legs, often on one side of your body
• difficulty walking
• changes to your vision or loss of vision 
• dizziness
• confusion 
• loss of coordination
• difficulty speaking, slurred or incoherent speech
• difficulty understanding what other people are saying 

In addition to TIAs and strokes, a carotid aneurysm can put pressure on nearby structures like the nerves or veins in your head or neck. This may cause symptoms including: 

• headaches
• neck pain
• facial swelling 
• a throbbing lump in your neck 
• a hoarse voice 
• difficulty swallowing
• changes in your vision 

How are aneurysms diagnosed?

Aneurysms do not usually cause any symptoms until they leak, rupture, or lead to other problems like blood clots or stroke. An aneurysm may be picked up during a screening, routine scan or during tests for another condition.

How an aneurysm is diagnosed depends on the type and location of the aneurysm.

Abdominal aortic aneurysms

Screening for abdominal aortic aneurysm (AAA) is recommended for all men aged 65 and over in the UK. Screening involves a quick, non-invasive, and painless procedure called an ultrasound scan where a probe is moved over your abdomen to check your aorta for any weaknesses in the arterial wall.

Cerebral aneurysms

There is currently no routine screening programme for cerebral aneurysms in the UK. Screening for brain aneurysms is normally only recommended for people at risk of having a brain aneurysm that may rupture in the future. You are considered at increased risk of brain aneurysm if you have two or more close (first-degree) relatives such as a mother, father, sister, or brother who have experienced a subarachnoid haemorrhage. If you think you may be at risk of developing a brain aneurysm, speak to your consultant.

A cerebral aneurysm is usually diagnosed using a procedure called angiography. During angiography, a narrow, flexible tube called a catheter is inserted into one of your blood vessels under local anaesthetic. The catheter is guided into the blood vessels in your neck using X-rays and a special dye is injected into the arteries of the brain to identify any aneurysms. 

Sometimes angiography may be performed using scans such as MRI or CT instead of X-rays. 

How is an aneurysm treated?

Most aneurysms grow slowly, around 1–2mm per year, and an aneurysm is usually only treated if it has ruptured or if there is a risk that it will rupture.

Active observation

Active observation involves having regular check-ups to monitor your aneurysm closely to check its size and assess the risk of rupture. Your consultant will also advise you about lifestyle changes such as stopping smoking, losing weight and eating a healthier diet. They may also prescribe medication to lower your blood pressure.

Surgery

If your aneurysm is large, fast-growing, causing unpleasant or dangerous symptoms, or there is a risk that it may rupture, your consultant may recommend surgery. If an aneurysm ruptures, emergency surgery is required.

Surgery for abdominal aortic aneurysm (AAA) 

There are two types of surgery used to treat abdominal aortic aneurysms (AAA):

• open repair - this type of open surgery is performed through a large incision in the abdomen and the aorta is repaired using a graft 
• endovascular aneurysm repair (EVAR) - this is a minimally invasive (keyhole) surgery that is performed through a small incision in the groin. During the procedure, special instruments are inserted via a catheter into an artery, and a stent and a graft are put in place to support the aneurysm

Surgery for cerebral aneurysms

There are two types of surgery used to treat cerebral aneurysms:

• neurosurgical clipping - a procedure where the aneurysm is sealed shut with a tiny metal clip. In some cases, blood is diverted around the clipped area using a blood vessel from another part of your body
• endovascular coiling - a thin flexible tube called a catheter is inserted into an artery in your leg or groin and guided to the aneurysm. Tiny platinum coils are then passed through the catheter to the aneurysm preventing blood from entering and sealing it.

Your consultant will decide whether clipping or coiling is the most suitable procedure for you, depending on the size, shape and location of your aneurysm.

Summary

An aneurysm is a weakening in the artery wall that can bulge out and in severe cases, may rupture, causing life-threatening internal bleeding.

Aneurysms can occur in various places around the body but are most common in the abdominal part of the aorta and the brain. Most aneurysms don't cause symptoms, but aneurysms that get very large, cause troublesome symptoms, or lead to secondary problems like blood clots can be treated with surgery.