A brain aneurysm occurs when a weak spot in your brain’s arterial wall bulges and fills with blood. It may also be called an intracranial aneurysm or cerebral aneurysm.
A brain aneurysm is a potentially life-threatening condition that can affect a person at any age. If a brain aneurysm bursts, it’s an emergency situation that can result in a stroke, brain damage, and even death if not treated immediately.
Not all aneurysms will rupture. Around 6 million people in the United States have aneurysms that haven’t ruptured, according to the Brain Aneurysm Foundation. An estimated 50 to 80 percent of all aneurysms never rupture in a person's lifetime.
Only about 30,000 of people in the United States experience ruptured aneurysms each year. Forty percent of ruptured aneurysms are fatal.
Brain aneurysms can take several forms. Stanford Health Care states that almost 90 percent are saccular, or "berry," aneurysms. This type forms a sac outside the artery that looks like a berry.
A fusiform aneurysm is an uncommon aneurysm that causes the artery to bulge all the way around.
A dissecting aneurysm is a tear in one of an artery’s several linings. It can leak blood into the other layers and balloon out or block the artery.
Some events encourage the development or rupture of an aneurysm in the brain. A study in the American Heart Association's journal Stroke concluded that the following factors may trigger the rupture of an existing aneurysm:
- excessive exercise
- coffee or soda consumption
- straining during bowel movements
- intense anger
- sexual intercourse
Some aneurysms develop over the course of a person’s lifetime, some are inherited, and some result from brain injuries.
Autosomal dominant polycystic kidney disease (ADPKD) is an inherited condition that affects kidney function. It also produces cobweb-like, fluid-filled pockets (cysts) in brain tissue. The condition raises blood pressure, which weakens blood vessels in the brain and elsewhere in the body.
Marfan’s syndrome is also inherited and affects the genes that control the formation of the body’s connective tissue. Damage to the structure of the arteries creates weaknesses that can lead to brain aneurysms.
A traumatic brain injury can tear the tissue and create what’s known as a dissecting aneurysm. A serious infection in the body can lead to an aneurysm if the infection damages the arteries. Smoking and chronic high blood pressure are also sources of many brain aneurysms.
Brain aneurysms can affect anyone, but people with atherosclerosis (hardening of the arteries) are at high risk of forming brain aneurysms.
The Brain Aneurysm Foundation also states that brain aneurysms are most common in people between 35 and 60 years old. Women are more likely to get aneurysms than men due to low estrogen levels after menopause. If aneurysms run in your immediate family, your risk of having one is higher.
Other risk factors for brain aneurysms include:
- older age
- drug abuse, especially cocaine
- alcohol abuse
- congenital problems that affect the arterial walls, such as Ehlers-Danlos syndrome
- head injury
- cerebral arteriovenous malformation
- congenital narrowing of the aorta known as coarctation
Aneurysms are unpredictable and may not show any symptoms until they rupture. Large or ruptured aneurysms will usually show definite symptoms and require emergency medical care.
The symptoms and warning signs of an aneurysm vary based on whether it’s ruptured or not.
Symptoms of an unruptured aneurysm include:
- headache or pain behind or above the eye, which can be mild or severe
- blurred or double vision
- visual deficits
See your doctor as soon as possible if you experience any of these symptoms.
Symptoms of a ruptured aneurysm include:
- sudden, severe headache, "the worst headache of my life"
- neck stiffness
- blurry or double vision
- sensitivity to light
- drooping eyelid
- trouble speaking or a change in awareness and mental state
- trouble walking or dizziness
- nausea or vomiting
- seizure (convulsion)
- loss of consciousness
If you have an aneurysm that is "leaking," you may only experience a sudden, severe headache.
Seek emergency medical attention right away if you experience one or more of these symptoms.
Unless an aneurysm ruptures, it may be difficult to diagnose the condition. Doctors can use certain tests to locate aneurysms in people who have family histories of the condition, risk factors, and inherited, aneurysm-related health issues.
CT and MRI scans take pictures of the brain tissues and arteries. CT scans take several X-rays and then provide a 3-D image of your brain on a computer. MRI scans work by scanning your brain with radio waves and magnetic fields and creating images.
CT scans are better at revealing bleeding that may already be present. A spinal tap, where a doctor draws fluid from the spine, can check for signs of bleeding in the brain. Cerebral angiograms can also check for bleeding and any abnormalities in the brain arteries.
If the aneurysm is accessible, surgery can repair or cut off blood flow to the aneurysm. This can prevent further growth or a rupture. Some surgeries include:
- surgical clipping, in which an aneurysm is closed using a metal clip
- endovascular coiling, in which a catheter is inserted through an artery to your aneurysm and blood flow is blocked, which ultimately closes off the aneurysm
Several lifestyle changes can help you manage aneurysms, including:
- quitting smoking
- eating a diet of fruit, vegetables, whole grains, lean meat, and low-fat dairy products
- exercising regularly, but not excessively
- managing high blood pressure or high cholesterol
Pressure from the blood leaking into your brain from a ruptured aneurysm can build up quickly. If the pressure becomes too high, you can lose consciousness. Death can occur in some cases.
After a brain aneurysm ruptures, it can rupture again at any time, even after treatment. Your brain’s blood vessels can also become narrow without warning (vasospasms) in response to elevated pressure around the brain.
Other complications include:
- hydrocephalus, in which cerebrospinal fluid circulation is impaired
- hyponatremia, or low sodium levels due to the brain injury
Be vigilant in monitoring an aneurysm for signs of rupture. If you get immediate treatment for a rupture, your survival and recovery rates are much higher than if you don’t seek emergency medical care right away.
Recovery in the hospital from surgery on an unruptured aneurysm is usually quick. For surgeries involving a ruptured aneurysm, maximum recovery can take weeks to months, and it’s possible you may never fully recover, depending on the severity of the damage.
Be alert about warning signs. If you have any risk factors, see your doctor immediately for an examination. Unruptured brain aneurysms are serious and need to be addressed as soon as possible once they are discovered. Leaking or ruptured brain aneurysms are a medical emergency and require critical care management from experienced physicians in order to ensure the best possible outcome.
Written by: Brindles Lee Macon, Tim Jewell and Matthew Solan
Medically reviewed on Sep 01, 2016 by Graham Rogers, MD