A cerebral aneurysm (also called an intracranial aneurysm or brain aneurysm) is a bulging, weakened area in the wall of an artery in the brain, resulting in an abnormal ballooning of the artery that is at risk for rupturing. A cerebral aneurysm more often happens in an artery located in the front part of the brain that supplies oxygen-rich blood to the brain tissue. Arteries anywhere in the brain can develop aneurysms. A normal artery wall is made up of 3 layers. The wall where the aneurysm forms is thin and weak because of an abnormal loss or absence of the muscular layer of the artery wall, leaving only 2 layers. There are several types of aneurysms:
Most cerebral aneurysms present without any symptoms and are small in size (less than 10 millimeters, or less than four-tenths of an inch, in diameter). Smaller aneurysms may have a lower risk of rupture.
Currently, the cause of cerebral aneurysms is not clearly understood. Brain aneurysms are associated with several factors. This includes smoking, high blood pressure, and family history (genetic). The ultimate cause of a brain aneurysm is an abnormal breaking down and weakening in the wall of an artery, and the effects of pressure from the pulsations of blood being pumped forward through the arteries in the brain. Certain locations of an aneurysm may create greater pressure on the aneurysm, such as the area where the artery divides into smaller branches.
Inherited risk factors associated with aneurysm formation may include the following:
Acquired risk factors associated with aneurysm formation may include the following:
Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop disease and have no known risk factors. Knowing your risk factors to any disease can help to guide you into the appropriate actions. These include changing behaviors and being monitored for the disease.
The presence of a cerebral aneurysm may not be known until it ruptures. Most cerebral aneurysms have no symptoms and are small in size (less than 10 millimeters, or less than four-tenths of an inch, in diameter). Smaller aneurysms may have a lower risk of rupture.
However, occasionally there may be symptoms that happen before a rupture due to a small amount of blood that may leak. This is called "sentinel hemorrhage" into the brain. Some aneurysms are symptomatic because they press on adjacent structures, such as nerves to the eye. They can cause visual loss or diminished eye movements, even if the aneurysm has not ruptured.
The symptoms of an unruptured cerebral aneurysm include the following:
The first evidence of a cerebral aneurysm is most often a subarachnoid hemorrhage (SAH), due to rupture of the aneurysm. This may cause symptoms such as:
The symptoms of a cerebral aneurysm may resemble other problems or medical conditions. Always talk with your healthcare provider for a diagnosis.
A cerebral aneurysm is often discovered after it has ruptured or by chance during diagnostic exam, such as computed tomography (CT scan), magnetic resonance imaging (MRI), or angiography that are being done for other reasons.
In addition to a complete medical history and physical exam, diagnostic procedures for a cerebral aneurysm may include:
Your healthcare provider will figure out the best treatment for you based on:
Depending on your situation, the healthcare provider will make recommendations for the intervention that is appropriate. Whichever intervention is chosen, the main goal is to decrease the risk of subarachnoid hemorrhage, either initially or from a repeated episode of bleeding.
Many factors are considered when making treatment decisions for a cerebral aneurysm. The size and location of the aneurysm, the presence or absence of symptoms, the person’s age and medical condition, and the presence or absence of other risk factors for aneurysm rupture are considered. In some cases, the aneurysm may not be treated and the person will be closely followed by a healthcare provider. In other cases, surgical treatment may be indicated.
There are two primary surgical treatments for a cerebral aneurysm:
Although a cerebral aneurysm may be present without symptoms, the most common initial symptom of a cerebral saccular aneurysm is a sudden headache from a subarachnoid hemorrhage (SAH) or bleeding in the space between the brain and the membranes that cover the brain. Minor subarachnoid hemorrhage most often happens after head injury. Major subarachnoid hemorrhage is most commonly from a ruptured cerebral saccular aneurysm. A sudden headache associated with SAH is a medical emergency.
Increased risk for aneurysm rupture is associated with aneurysms that are over 10 millimeters (less than four-tenths of an inch) in diameter, in a particular location (circulation in the back portion of the brain), and/or previous rupture of another aneurysm. A significant risk of death is associated with the rupture of a cerebral aneurysm.
Hemorrhagic strokes happen when a blood vessel that supplies the brain ruptures and bleeds. When an artery bleeds into the brain, brain cells and tissues do not receive oxygen and nutrients. In addition, pressure builds up in surrounding tissues and irritation and swelling happens. About 20% of strokes are caused by hemorrhagic bleeding.
Controlling your risk factors may decrease your risk of having an aneurysm. These risk factors include:
Although these risk factors increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop the disease. Others develop the disease and have no known risk factors. Knowing your risk factors to any disease can help to guide you into the appropriate actions. These include changing behaviors and being clinically monitored for the disease.
Any person experiencing some or all of the following symptoms, regardless of age, should undergo immediate and careful evaluation by a healthcare provider:
Ruptured brain aneurysms usually result in a subarachnoid hemorrhage (SAH). This is defined as bleeding into the space around the brain called the subarachnoid space. A SAH can be life-threatening.
You should seek medical attention immediately if you are experiencing some or all of these symptoms:
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