An aneurysm is a ballooning at a weak spot in an artery wall. An aneurysm's walls can be thin enough to rupture. The illustration shows an individual with an unruptured aneurysm. The inset shows what happens when the aneurysm ruptures.
Aneurysms can lurk without symptoms, but screening can save lives. Spinal Claudication
A brain aneurysm (AN-yoo-riz-um) — also known as a cerebral aneurysm or intracranial aneurysm — is a bulge or ballooning in a blood vessel in the brain. An aneurysm often looks like a berry hanging on a stem.
Experts think brain aneurysms form and grow because blood flowing through the blood vessel puts pressure on a weak area of the vessel wall. This can increase the size of the brain aneurysm. If the brain aneurysm leaks or ruptures, it causes bleeding in the brain, known as a hemorrhagic stroke.
Most often, a ruptured brain aneurysm occurs in the space between the brain and the thin tissues covering the brain. This type of hemorrhagic stroke is called a subarachnoid hemorrhage.
Brain aneurysms are common. But most brain aneurysms aren't serious, especially if they're small. Most brain aneurysms don't rupture. They usually don't cause symptoms or cause health problems. In many cases, brain aneurysms are found during tests for other conditions.
However, a ruptured aneurysm quickly becomes life-threatening and requires medical treatment right away.
If a brain aneurysm hasn't ruptured, treatment may be appropriate in some cases. Treatment of an unruptured brain aneurysm may prevent a rupture in the future. Talk with your health care provider to make sure you understand the best options for your specific needs.
A saccular aneurysm is known as a berry aneurysm. It's the most common type of brain aneurysm. It looks like a berry hanging from a vine. Another type of aneurysm is a fusiform aneurysm. It causes ballooning or bulging of the artery.
Most brain aneurysms that haven't ruptured don't cause symptoms. This is especially true if they're small. Brain aneurysms may be found during imaging tests that are done for other conditions.
However, a ruptured aneurysm is a very serious condition, typically causing a severe headache. And if an unruptured aneurysm presses against brain tissue or nerves, it may cause pain and other symptoms.
A sudden, severe headache is the key symptom of a ruptured aneurysm. This headache is often described by people as the worst headache they've ever experienced.
In addition to a severe headache, symptoms of a ruptured aneurysm can include:
In some cases, an aneurysm may leak a slight amount of blood. When this happens, a more severe rupture often follows. Leaks may happen days or weeks before a rupture.
Leaking brain aneurysm symptoms may include:
An unruptured brain aneurysm may not have any symptoms, especially if it's small. However, a larger unruptured aneurysm may press on brain tissues and nerves.
Symptoms of an unruptured brain aneurysm may include:
Seek immediate medical attention if you develop a:
If you're with someone who complains of a sudden, severe headache or who loses consciousness or has a seizure, call 911 or your local emergency number.
Vivien Williams: An aneurysm is an abnormal bulge or ballooning in the wall of a blood vessel.
Bernard Bendok, M.D., Neurosurgery, Mayo Clinic: A portion of these patients will go on to have a rupture. And the challenge with rupture is that it's unpredictable.
Vivien Williams: Dr. Bernard Bendok says a ruptured aneurysm is a medical emergency that can cause life-threatening bleeding in the brain.
Dr. Bendok: The typical presentation is somebody who has the worst headache of their life.
Vivien Williams: Fast treatment is essential. It includes open surgery or less-invasive options, such as sealing the ruptured artery from within the blood vessel with metal coils and/or stents.
Dr. Bendok says 1 to 2 percent of the population have aneurysms and only a small percentage of that group will experience a rupture. People who have a family history of aneurysms, have polycystic kidney disease, connective tissue disease, and people who smoke are at increased risk of rupture and should consider screening. If a rupture happens, fast treatment can save lives.
For the Mayo Clinic News Network, I'm Vivien Williams.
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Brain aneurysms are caused by thinning artery walls. Aneurysms often form at forks or branches in arteries because those areas of the vessels are weaker. Although aneurysms can appear anywhere in the brain, they're most common in arteries at the base of the brain.
Several factors can contribute to weakness in an artery wall. These factors may increase the risk of a brain aneurysm or aneurysm rupture.
Some of these risk factors develop over time. But some conditions present at birth can increase the risk of developing a brain aneurysm.
Some types of aneurysms may occur after a head injury or from certain blood infections.
There are some factors that make it more likely an aneurysm will rupture. They include:
When a brain aneurysm ruptures, the bleeding usually lasts only a few seconds. However, the blood can cause direct damage to surrounding cells and can kill brain cells. It also increases pressure inside the skull.
If the pressure becomes too high, it may disrupt the blood and oxygen supply to the brain. Loss of consciousness or even death may occur.
Complications that can develop after the rupture of an aneurysm include:
In many cases, brain aneurysms can't be prevented. But there are some changes you can make to lower your risk. They include quitting smoking if you smoke. Also work with your health care provider to lower your blood pressure if it's high. Don't drink large amounts of alcohol or use drugs such as cocaine.
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