What is a Brain Aneurysm?
A brain aneurysm is a bulge or ballooning in a blood vessel in the brain. Brain aneurysms — also called cerebral aneurysm or intracranial aneurysm — form within the wall of an artery in the brain due to a weakness in the blood vessel. Over time, the weak area becomes thinner and bulges out due to blood flowing and pounding against the vessel wall. As time passes and the bulging artery becomes thinner, the aneurysm can rupture, causing bleeding into the brain.
Types of Brain Aneurysms
There are two types of aneurysms that can occur in the brain:
- Saccular Aneurysm: The most common type of aneurysm, this is also called a "berry aneurysm" because of its shape. A saccular aneurysm looks like a sac or berry that forms most commonly at an intersection, or "Y," in the network of arteries located in the base of the brain (also called the circle of Willis).
- Fusiform Aneurysm: A less common type of aneurysm, a fusiform aneurysm looks like a widening of the entire arterial wall in the area of weakness.
Unruptured Aneurysms & Ruptured Aneurysms
Most brain aneurysms form without any symptoms. An unruptured brain aneurysm may be found during brain imaging — such as an MRI — when a patient is being screened for another condition. If an aneurysm is discovered, it's important to see a neurosurgeon who is an expert in diagnosing, managing, and treating brain aneurysms. Certain people may be at a higher risk for brain aneurysm. If you discover that you are at a high risk, it's important to discuss screening tests with your doctor.
A ruptured brain aneurysm is a serious condition and requires immediate medical attention. Symptoms of a ruptured aneurysm most often include sudden onset of a severe headache most patients describe as the worst headache they have felt in their life.
Brain Aneurysm Facts
- An estimated 6 million people in the United States have an unruptured brain aneurysm — one in 50 people.
- Brain aneurysms are more common in women than men — 3:2 ratio.
- About 10–15% of patients diagnosed with a brain aneurysm will have more than one aneurysm.
- Brain aneurysms occur most commonly in adults aged 35–60 but also can occur in children. Most aneurysms develop after age 40 and have no symptoms.
- Early and accurate diagnosis and treatment are critical to assuring good patient outcomes and survival.