An aneurysm is a weak area in the wall of a blood vesel that causes the blood vessel to bulge or balloon out. When an aneurysm occurs in a blood vessel of the brain, it is called a cerebral aneurysm.
Aneurysms in the brain occur when there is a weakened area in the wall of a blood vessel. An aneurysm may be present from birth (congenital) or it may develop later in life, such as after a blood vessel is injured.
There are many different types of aneurysms. A berry aneurysm can vary in size from a few millimeters to over a centimeter. Giant berry aneurysms can reach well over 2 centimeters. These are more common in adults. Multiple berry aneurysms are inherited more often than other types of aneurysms.
Other types of cerebral aneurysm involve widening of an entire blood vessel, or they may appear as a "ballooning out" of part of a blood vessel. Such aneurysms can occur in any blood vessel that supplies the brain. Atherosclerosis, trauma, and infection, which can injure the blood vessel wall, can cause cerebral aneurysms.
About 5% of the population has some type of aneurysm in the brain, but only a small number of these aneurysms cause symptoms or rupture. Risk factors include a family history of cerebral aneurysms, and certain medical problems such as polycystic kidney disease, coarctation of the aorta, and high blood pressure.
A person may have an aneurysm without having any symptoms. This kind of aneurysm may be found when an MRI or CT scan of the brain is done for another reason.
A cerebral aneurysm may begin to "leak" a small amount of blood. This may cause a severe headache that a patient may describe as "the worst headache of my life." Another phrase used to describe this is a sentinel headache. This means the headache could be a warning sign of a rupture days or weeks after the headache first happens.
Symptoms may also occur if the aneurysm pushes on nearby structures in the brain or breaks open (ruptures) and causes bleeding into the brain.
Symptoms depend on the location of the aneurysm, whether it breaks open, and what part of the brain it is pushing on, but may include:
A sudden, severe headache is one symptom of an aneurysm that has ruptured. Other symptoms of an aneurysm rupture may include:
NOTE: A ruptured aneurysm is a medical emergency. Seek immediate medical help.
An eye exam may show evidence of increased pressure in the brain (raised intracranial pressure), including swelling of the optic nerve or bleeding into the retina of the eye. A brain and nervous system (neurological) exam may show abnormal eye movement, speech, strength, or sensation.
The following tests may be used to diagnose cerebral aneurysm and determine the cause of bleeding in the brain:
Two common methods are used to repair an aneurysm:
If an aneurysm in the brain ruptures, it is an emergency that needs medical treatment and often requires surgery. Endovascular repair is more often used when this happens.
Even if there are no symptoms, your doctor may order treatment to prevent a future, possibly fatal rupture.
Not all aneurysms need to be treated right away. Those that are very small (less than 3 mm) are less likely to break open.
Your doctor will help you decide whether it is safer to have surgery to block off the aneurysm before it can break open (rupture).
Someone may be too ill to have surgery, or it may be too dangerous to treat the aneurysm because of its location.
Treatment may involve:
Once the aneurysm is repaired, prevention of stroke from blood vessel spasm may be necessary. This may include intravenous fluids, certain medications, and letting the blood pressure get high.
The outcome varies. Patients who are in deep comas after an aneurysm rupture generally do not do as well as those with less severe symptoms.
Ruptured cerebral aneurysms are often deadly. About 25% of people die within 1 day, and another 25% die within about 3 months. Of those who survive, about 25% will have some sort of permanent disability.
Go to the emergency room or call the local emergency number (such as 911) if you have a sudden or severe headache, especially if you also have nausea, vomiting, seizures, or any other neurological symptoms.
Also call if you have a headache that is unusual for you, especially if it is severe or your worst headache ever.
There is no known way to prevent the formation of a berry aneurysm. Treating high blood pressure may reduce the chance that an existing aneurysm will rupture. Controlling risk factors for atherosclerosis may reduce the likelihood of some types of aneurysms.
If unruptured aneurysms are discovered in time, they can be treated before causing problems.
The decision to repair an unruptured cerebral aneurysm is based on the size and location of the aneurysm, and the patient's age and general health. The risks involved in both operating and watchful waiting must be carefully considered.
Aneurysm - cerebral; Cerebral aneurysm
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Reviewed by: Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital; and David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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