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Australian radio host Kyle Sandilands announced on air yesterday that he and needs urgent brain surgery.

Typically an aneurysm occurs when a part of the wall of an artery (a type of blood vessel) becomes stretched and bulges out.

You can get an aneurysm , but they are most common in the brain’s arteries and the aorta, the large artery that leaves the heart.

Many people can have a brain aneurysm and never know. But a brain (or aortic) aneurysm that ruptures and bursts can be fatal.

So, what causes a brain aneurysm? And what’s the risk of rupture?

Weakness in the artery wall

Our arteries need strong walls because blood is constantly pumped through them and pushed against the walls.

An can develop if there is a weak part of an artery wall.

The walls of arteries are made of three layers: an inner lining of cells, a middle layer of muscle and elastic fibres, and a tough outer layer of mostly collagen (a type of protein). Damage to any of these layers causes the wall to become thin and stretched. It can then balloon outward, leading to an aneurysm.

and can cause weak artery walls and brain aneurysms in some people.

For all of us, our artery walls become weaker as we age, and brain aneurysms are more common as we get older. The to be detected is 50 (Sandilands is 53).

Females have a higher risk of brain aneurysm than males . Declining oestrogen around menopause reduces the collagen in the artery wall, causing it to become weaker.

High blood pressure can increase the risk of a brain aneurysm. In someone with high blood pressure, blood inside the arteries is pushed against the walls with greater force. This can .

Another called atherosclerosis can also . In atherosclerosis, plaques made mostly of fat build up in arteries and stick to the artery walls. This directly damages the cell lining, and weakens the muscle and elastic fibres in the middle layer of the artery wall.

Several lifestyle factors increase risk

Anything that increases inflammation or causes atherosclerosis or high blood pressure in turn increases your risk of a brain aneurysm.

affect all of these, and nicotine the artery wall.

Sandilands mentioned in discussing his diagnosis. He said:

The facts are, a life of cocaine abuse and partying are not the way to go.

Indeed, cocaine abuse . It causes very high blood pressure because it causes arteries to spasm and constrict. Cocaine use is also if a brain aneurysm ruptures.

and a also increase inflammation. can also cause atherosclerosis. And increases your blood pressure.

of more than 60,000 people found smoking and high blood pressure were the strongest risk factors for a brain aneurysm.

Is it always a medical emergency?

About will have a brain aneurysm, varying in size from in diameter. The majority are only discovered while undergoing imaging for something else (for example, head trauma), because small aneurysms may not cause any symptoms.

Larger aneurysms can cause symptoms because they can .

Sandilands described “” leading up to his diagnosis. Headaches can be due to from the aneurysm. They indicate a risk of the aneurysm rupturing in subsequent days or weeks.

Less than , often called a “brain bleed”. This causes a , which is a .

If it does occur, rupture of a brain aneurysm is : nearly one in four people will die within 24 hours, and one in two within three months.

If someone’s brain aneurysm ruptures, they usually experience a sudden, severe headache, often described as a “”. They may also have such as changes in vision, loss of movement, nausea, vomiting and loss of consciousness.

Surgery can prevent a rupture

Whether surgery will be used to treat a brain aneurysm depends on its size and location, as well as the age and health of the patient. The medical team will balance the potential benefits with the risks of the surgery.

A small aneurysm with low risk of rupture will usually .

However, once a brain aneurysm reaches , surgery is generally needed.

In , the surgeon will temporarily remove a small part of the skull, then cut through the coverings of the brain to place a tiny metal clip to close off the bulging part of the aneurysm.

Another option is (meaning within the vessel) coiling. A surgeon can pass a catheter into the femoral artery in the thigh, through the aorta to the brain. They can then place a coil inside the aneurysm which forms a clot to close off the aneurysm sac.

, usually the person will stay in hospital for up to a week. It can take for full recovery, though doctors may continue monitoring with annual imaging tests for a few years afterwards.

You can by not smoking, moderating alcohol intake, eating a healthy diet, exercising regularly and maintaining a healthy weight.

, Associate Professor of Medical Sciences, and , Senior Lecturer in Medical Sciences (Neuroscience),

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