Aneurysm, Brain

An aneurysm is an abnormal widening or ballooning of a portion of a blood vessel. A cerebral aneurysm refers to a blood vessel within your brain that weakens over time and undergoes such widening. This usually occurs at the junctions of the large arteries at the base of your brain, in an area called the Circle of Willis.

As the blood vessel weakens, it begins to bulge out like a balloon. Often, as an aneurysm develops, it forms a neck with an associated dome, or balloonlike structure. The larger the balloon becomes, the greater the risk it may burst. You would then bleed into your brain.

Autopsy studies have revealed that 3-6% of adults in the United States have aneurysms inside their brains. Fortunately, many of these aneurysms are small and not at risk to break. The rates of aneurysms found by accident when other studies are performed suggest that 8-10 million Americans have brain aneurysms. About 20-30% of people with an aneurysm will have more than 1. Each year, for every 100 people with an aneurysm, roughly 1 of them will suffer a rupture or break—a condition known as subarachnoid hemorrhage.

Currently no one can predict which aneurysms will rupture. Data suggest that aneurysms that rupture tend to be larger than 10 mm (0.4 in). About 25,000-30,000 cases of ruptured aneurysms occur in the US each year. About 40% of the people who suffer bleeding from an aneurysm die within the first month. Approximately another one third have residual major nervous system problems but survive.

Many are left with long-term memory problems. They may have difficulty in the following: thinking, perception, and performing simple daily activities.

People who have survived a rupture of a brain aneurysm are twice as likely as the general population to develop another aneurysm. If a second aneurysm occurs, these people are 6 times more likely to have another ruptured aneurysm and bleeding in their brain.

Aneurysms in the brain are considered to be acquired problems. They are not present at birth. Rather, they develop over a lifetime.

Other evidence indicates that genetic factors make some people more likely to develop brain aneurysms. The exact pattern of inheritance is not clear.

• According to several studies, up to 20% of people with bleeding from an aneurysm have a first- or second-degree relative with a brain aneurysm.
  
  
• These relatives are at higher risk for bleeding in the brain.
  
  
• In most families with brain aneurysms, the condition affects only 2-3 members of the extended family, and the method of inheritance is not apparent.

Associated conditions - A number of conditions are associated with brain aneurysms, as follows:

• Polycystic kidney disease - A genetic disorder characterized by the growth of numerous cysts in the kidneys
  
  
• Ehlers-Danlos syndrome - A group of inherited connective tissue disorders characterized by extreme flexibility of joints, easily stretched skin and easily damaged tissue
  
  
• Marfan syndrome – An inherited disorder of connective tissue, the glue and the scaffolding of your body, which leads to tissue with less strength and that can rupture easier 
  
  
• Neurofibromatosis – A group of 8 genetic disorders of the nervous system that primarily affect the development and growth of nerve cell tissues (These disorders cause tumors to grow on nerves and produce other abnormalities such as skin changes and bone deformities.)

Environmental factors: Significant evidence suggests that environmental factors make some people more likely to develop brain aneurysms.

• Brain aneurysms are very rare in children.
  
  
• The likelihood of having an aneurysm increases throughout life.
  
  
• Tobacco
  
  
  • Cigarette smoking is the only factor that has been consistently demonstrated to increase the risk of ruptured aneurysm.
    
    
  • Sustaining a rupture of a brain aneurysm is about 10 times more likely in a smoker than in a nonsmoker.
    
    
  • The more cigarettes smoked, the higher the risk.
  
  
• High blood pressure
  
  
  • Several studies have shown an increased risk for the development and rupture of brain aneurysms in people with high blood pressure.
    
    
  • Most experts believe that high blood pressure remains a risk factor but not to the extent that cigarette smoking is a risk.
  
  
• High cholesterol
  
  
  • The effect of high cholesterol remains unclear.
    
    
  • Three studies have looked at high cholesterol as a risk factor for aneurysm and rupture. Two studies showed no association and one study showed a relationship.
  
  
• Alcohol consumption
  
  
  • A moderate to high level of alcohol use is considered a risk factor for the rupture of a brain aneurysm.
    
    
  • It is unclear if alcohol use increases the risk of developing an aneurysm.
    
    
  • Binge drinking appears to dramatically increase the risk of subarachnoid hemorrhage from a ruptured aneurysm.

The initial symptom of a brain aneurysm may be a sudden, severe, catastrophic headache.

Most people will not be aware that they have an aneurysm in the brain until the aneurysm ruptures, causing the severe headache. For the majority of people, symptoms do not come directly from the aneurysm, but rather from the following:

• Symptoms of a ruptured aneurysm 
  
  
  • Severe headache
    
    
    • If you have a history of headaches, such as migraine or tension headaches, you may experience a headache uniquely different from your normal pattern.
      
      
    • You should consider any severe headache different from your customary headache as suspicious for a ruptured aneurysm. You may experience the worst headache of your life, which may also be a sign of a stroke.
      
      
    • Up to 50% of people with a ruptured aneurysm will suffer a warning (prodromal) headache several days or even weeks before the rupture. The average is about 2 weeks.
      
      
    • This warning headache is thought to be due to minor blood leakage, without rupture of the aneurysm, and is commonly referred to as a "sentinel headache."
    
    
  • Neck stiffness
    
    
  • Nausea
    
    
  • Vomiting
    
    
  • Sensitivity to light
  
  
• These symptoms may be followed rapidly by an alteration in mental status ranging from confusion to coma.
  
  
• Seizures occur in about 25% of people with a ruptured aneurysm.
  
  
• Some people will have symptoms of an enlarging, unruptured aneurysm.
  
  
  • A dilated pupil in 1 eye
    
    
  • Visual field defects: This refers to the inability to see objects that are in the direction you are looking. For instance, if you are looking directly at a large screen TV, you may not be able to see the whole screen at once. There may be a "hole" in the center or off to the sides that you simply cannot see while looking straight ahead.
    
    
  • Inability to move 1 eye in all directions
    
    
  • Pain above or behind the eye
    
    
  • Pain in the temple, in the back of the skull, or the neck, depending on the location of the aneurysm

Call your doctor at once. Evaluation for a suspected rupture of a brain aneurysm must be performed immediately, most appropriately in a hospital's emergency department.

• If you have any questions about whether or not there is cause for concern, call your doctor for advice. The doctor most likely will advise you to seek care in a hospital’s emergency department.



• If you are a close relative of someone with a known aneurysm, or ruptured aneurysm, inform your doctor. Your doctor will want to be aware of such information. You should realize, though, that you seldom need to be screened for an aneurysm unless you are having symptoms.

A ruptured aneurysm is a life-threatening event. Any headache that is severe and comes on suddenly should prompt immediate evaluation by a doctor, particularly if the headache is associated with any of the following:

• Seizure



• Vomiting



• Alteration in consciousness



• Neurological defects such as inability to speak, to move an extremity, walk, severe dizziness, changes in your vision



• This evaluation most appropriately occurs in the emergency department.



• Rupture of an aneurysm frequently occurs at times of stress or physical exertion. Any severe headache, with or without the symptoms described here, should be investigated immediately.



• People who experience migraine headaches with an established headache pattern should seek evaluation for any headache that is severe, comes on suddenly, and is different from their usual headache pattern. This might include the following:
  
  
  • A much more intense headache
  
  
  
  • A headache of maximum intensity at the onset
  
  
  
  • A headache without forewarning, among other symptoms


• Family members, particularly siblings, of people with known aneurysms or a history of ruptured aneurysm are at higher risk for rupture and should seek care promptly for any of these symptoms:
  
  
  • Unusual headache
  
  
  
  • Head pain
  
  
  
  • Eye pain
  
  
  
  • Visual disturbances


• Anyone who has survived a ruptured aneurysm should be especially concerned and seek care immediately for any new or suspicious headache.

If the doctor suspects a ruptured aneurysm, you will have a complete physical exam, with particular attention to the neurologic exam.

• The doctor will be very concerned about your level of consciousness and the presence or absence of localized nerve problems.
  
  
• The doctor will seek a quick focused history from you, or from family members if you are unable to give information.
  
  
• The doctor quickly will try to determine the likelihood that you have a ruptured aneurysm as opposed to other causes of headache or alterations of consciousness.
  
  
• Your physical examination and the history of the event will guide further diagnostic testing.
  
  
• Any time you become unstable, such as changes in blood pressure, decreasing level of alertness, or difficulty breathing, the doctor may perform life-saving maneuvers. Such maneuvers might include placing a tube down your throat to protect your airway and provide adequate breathing.
  
  
• If you have no symptoms, the doctor may include in your workup many of the following tests, although the tests may be performed on an outpatient basis.
  
  
  • A CT scan of your brain: A CT scan will detect acute bleeding from a ruptured aneurysm about 90% of the time.
    
    
    • Aside from the bleeding, CT scans are able to detect some complications of a ruptured aneurysm such as swelling of the brain.
      
      
    • A plain CT scan is not a good test to use to detect aneurysms that have not ruptured.
    
    
  • A lumbar puncture (spinal tap): If the CT scan shows no evidence of bleeding in your brain, the doctor may perform a lumbar puncture.
    
    
    • This procedure involves placing a needle into your spinal canal in the low back, below the level at which the spinal cord ends.
      
      
    • The doctor will collect spinal fluid and send it to the lab to look for the presence of blood.
      
      
    • If blood is present, particularly if the spinal fluid is yellow, you have bleeding in the brain and the workup proceeds further.
    
    
  • Cerebral angiography: The doctor likely will perform this test next.
    
    
    • The doctor places a catheter into your groin while you are under local anesthesia. It is threaded up toward your brain and then injects an x-ray contrast dye into your arteries.
      
      
    • The doctor will take several x-rays to be reviewed by neurosurgeon and a radiologist.
      
      
    • These x-rays help the neurosurgeon locate the aneurysm and determine how to manage it.
      
      
    • They also will show the presence of other aneurysms.
    
    
  • Magnetic resonance angiography: Like an MRI, this test is very useful for detecting unruptured aneurysms and for screening high-risk patients.
    
    
    • It is noninvasive and virtually risk-free.
      
      
    • Doctors consider the test inadequate for planning surgery.
    
    
  • Helical CT angiography: This test is a recent addition to the diagnostic possibilities.
    
    
    • It does involve administering x-ray contrast dye and is not risk-free.
      
      
    • It has the potential to aid in surgical planning in that it demonstrates the relation of the aneurysm to bony structures of the skull base.

|Self-Care at Home|

A suspected rupture of a brain aneurysm is a true medical emergency. No specific treatment can be given at home.

|Medical Treatment|

• Ruptured brain aneurysm
  
  
  • Doctors locate the aneurysm with cerebral angiography and then surgically clip it.
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  • Doctors generally perform the clipping within 72 hours because an aneurysm has a 30% risk of rebleeding. This risk peaks at 7 days and carries with it a 60% risk of poor outcome or death.
    
    
  • For people with severe symptoms such as a coma, doctors often delay surgery and instead use other options.
    
    
  • Options include interventional radiologic procedures such as placing a coil inside the blood vessel during the cerebral angiography. You can think of the coil as a clip placed within the aneurysm, rather than on the outside.
    
    
  • Either the surgical clip or placing a coil effectively removes the aneurysm from your blood circulation system and eliminates the risk of rebleeding.
    
    
  • Clipping also allows the doctor to more aggressively manage the associated spasm of your arteries that is likely to follow.
    
    
  • Virtually all people with a brain aneurysm will receive nimodipine (Nimotop), a calcium channel blocker that helps prevent the blood vessel spasm that regularly accompanies ruptured aneurysms.
    
    
    • Additional methods of treating vessel spasm include inducing high blood pressure with fluids and medications in an effort to increase blood flow through areas of spasm and narrowing.
      
      
    • Doctors will use a special ultrasound exam, a transcranial Doppler ultrasound, to assess the degree of spasm and help guide treatment.
    
    
  • Additional treatments that may be required depend on the severity of your symptoms and information obtained by diagnostic studies. These may include the following:
    
    
    • A drainage device may be placed through your skull to allow drainage of fluid and decrease pressure within your brain.
      
      
    • Antiseizure medications may prevent seizures that frequently accompany ruptured aneurysms.
      
      
    • Glucocorticoids, anti-inflammatory steroids, occasionally used to help control swelling in the brain, remain controversial because no proven benefit has been shown.
      
      
    • Antifibrinolytic agents may be used to stabilize the clot within an aneurysm in people who cannot undergo a clipping procedure. Increasing numbers of people develop delayed strokes, so doctors now use antifibrinolytic agents infrequently.
  
  
• Unruptured brain aneurysm
  
  
  • The best treatment would be to prevent rupture of an aneurysm once it is discovered.
    
    
  • Larger aneurysms are more likely to bleed than smaller ones.
    
    
  • Currently there is no reliable method of determining which aneurysms will rupture. For this reason doctors offer a variety of opinions on how to treat an intact aneurysm once it is discovered.
    
    
  • Treatment most likely will be a surgical clipping procedure or placement of a coil in the aneurysm similar to those in a ruptured aneurysm.

|Follow-up|

• After you have been diagnosed with a cerebral aneurysm, your doctor will advise you to modify any risk factors you may have.
  
  
  • This may mean quitting the use of alcohol and tobacco.
    
    
  • Your doctor likely will follow your blood pressure closely.
    
    
  • Your doctor may add medications to help control your blood pressure.
  
  
• Your doctor probably will recommend that you have regular physical examinations to monitor for symptoms of an enlarging aneurysm.
  
  
  • The doctor will be particularly interested in changes in your vision, headache patterns, and examination of your eyes.
    
    
  • An examination of your nerve functions likely will be performed.

|Prevention|

• At this time doctors do not recommend screening family members for aneurysms that show no symptoms.
  
  
  • If you have 1 close family member who has had a rupture of an aneurysm, your lifetime risk of a ruptured aneurysm is about 1% at age 50 years and 2% at age 70 years.
  
  
  
  • The risk of surgery to repair an aneurysm that exists but has no symptoms is 2-5%, which is clearly greater than the risk of hemorrhage into the brain for such people.


• Screening is recommended for families who show no symptoms but who have 2 members with a ruptured aneurysm.
  
  
  • Siblings over age 30 years are at particularly high risk and should be screened.
  
  
  
  • Current recommendations are that family members have an MRI angiography or helical CT angiography every 5 years.


• The major modifiable risk factors for rupture of an aneurysm are the following. You can influence 2 of these directly. In cooperation with your doctor, you nearly always can control your blood pressure as well.
  
  
  • Do not smoke cigarettes.
  
  
  
  • Control high blood pressure.
  
  
  
  • Avoid binge drinking.
  
  
  
  • Additionally, the use of amphetamines (speed), cocaine, and even most medications for the common cold can all dramatically increase blood pressure and increase the risk of rupture in people with brain aneurysms.

|Outlook|

Most aneurysms show no symptoms until they rupture. The single most important predictor of the outcome of the subarachnoid hemorrhage is your physical condition when you arrive at the hospital.

• Once an aneurysm has ruptured, recovery depends on the degree of bleeding and associated problems.
  
  
  • Rebleeding
    
    
  • Increased pressure within your brain
    
    
  • Subsequent artery spasms and narrowing of the arteries of your brain
  
  
• Doctors direct treatment at the time your rupture is diagnosed toward preventing these complications.
  
  
• Once you are diagnosed with an unruptured aneurysm the main question is what to do about it.
  
  
  • Most experts agree that for aneurysms smaller than 10 mm (0.4 in), if you have no history of bleeding into your brain, the risks of surgery outweigh the potential benefits.
    
    
    • Factors that would favor surgery are high blood pressure that is poorly controlled and symptoms related to compression of nerve tissue by the aneurysm.
      
      
    • Factors weighing against surgery include location of the aneurysm in a surgically difficult area and co-existing illnesses that would increase your risk of surgery.
    
    
  • A promising treatment for brain aneurysms involves placing a metallic coil inside the aneurysm. The coil causes a clot to form inside, and the clot blocks the aneurysm from your circulation system.
    
    
    • This markedly decreases the chance of rupture.
      
      
    • The risks of the procedure are much lower than for surgery, but the long-term outcomes are not yet known.
      
      
    • Current experience indicates that this technique works best for smaller aneurysms. It may, in fact, cause an increased risk of rupture when used in very large aneurysms.

Brain Aneurysm Foundation
12 Clarendon Street
Boston, MA 02116
(617) 723-3870

NIH Neurological Institute
PO Box 5801
Bethesda, MD 20824
(800) 352-9424

|Web Links|

National Institute of Neurological Disorders and Stroke, Cerebral Aneurysm Information Page

Wake Forest University School of Medicine, Department of Neurosurgery, Brain Aneurysm/Subarachnoid Hemorrhage

American Society of Interventional & Therapeutic Neuroradiology, Brain Aneurysm Resources

brain aneurysm, intracranial aneurysm, Berry aneurysm, saccular aneurysm, cerebral aneurysm, ballooned vessel, subarachnoid hemorrhage, bleeding in the brain, worst headache of your life, severe headache, aneurysm, Circle of Willis, polycystic kidney disease, Ehlers-Danlos syndrome, Marfan syndrome, neurofibromatosis, stroke, warning headache, prodromal headache, sentinel headache, unruptured brain aneurysm, ruptured brain aneurysm, brain swelling

Author: Nicholas Y Lorenzo, MD, Chief Editor, Neurology; Consulting Staff, Neurology Specialists and Consultants.

Coauthor(s): William R Fraser, DO, Associate Clinical Professor, Department of Emergency Medicine, Ohio University College of Osteopathic Medicine; Program Director, Department of Emergency Medicine, Doctors Hospital.

Editors: Alan D Forker, MD, Program Director of Cardiovascular Fellowship, Professor of Medicine, Department of Internal Medicine, University of Missouri at Kansas City School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, ; Anthony Anker, MD, FAAEM, Attending Physician, Emergency Department, Mary Washington Hospital, Fredericksburg, VA.