Intracerebral Aneurysm

ExitCare ImageAn intracerebral aneurysm is a small, thin, walled out-pouching or enlargement of one of the large blood vessels that supply blood to the brain. Aneurysms are a risk to health because they may leak or break and bleed into the brain. They often occur where the larger vessels branch near the base of the brain. Leaking or rupture can also occur into the fluid-filled spaces that surround the brain (the subarachnoid space).

Rupture of an aneurysm leads to subarachnoid hemorrhage (SAH). This occurs most often in patients between 40 and 60 years of age. It occurs equally between men and women. Cigarette smoking and excess alcohol use has been shown to increase the risk of rupture. Intracerebral aneurysms are associated with other kidney, blood vessel, and muscle diseases. High blood pressure is also a risk factor, but it seems to be less important, since aneurysms often occur in persons with normal blood pressure. Pregnancy has not been associated with an increased incidence of this problem.


  • An accident (trauma), infection, or cancer disease.

  • A problem with development of the lining of the artery. This causes a thinning that is weaker than the rest of the artery. This can rupture or leak.

  • A small percentage the problem is passed down from parents (hereditary).


  • Prior to rupture, most aneurysms produce no problems. Sometimes, if the aneurysm is getting large, it may cause problems due to increased pressure on the brain. Some of these problems may be:

  • Double vision.

  • Loss of vision.

  • Numbness or pain in the face.

  • Enlarged pupil size.

  • A drooping eyelid.

  • Headache.

  • Usually, patients who have an aneurysm rupture experience sudden onset of a severe headache, often described as "the worst headache of my life." This can happen along with the loss of consciousness (fainting) and sometimes vomiting. A stiff neck often follows.

  • Rupture of an aneurysm usually occurs while the person is active rather than during sleep. In as many as half of cases, patients experience a warning headache due to a small leakage of blood. This can precede a major bleed by several hours to several weeks.

  • These milder headaches are often associated with feeling sick to your stomach (nausea) and vomiting. These warning headaches may be mistaken for migraine headaches.


  • A CT scan of the head will usually confirm blood within the brain or in the space surrounding the brain. The blood will show up if an aneurysm has already bled or ruptured.

  • If the results of the CT scan are not certain, a spinal tap is sometimes used. This test looks for blood in the fluid which surrounds the brain and spinal cord (cerebrospinal fluid).

  • One way to diagnose an intracerebral aneurysm is to perform a test called Carotid and vertebral angiography. This is a test in which a liquid called a "contrast material" is injected into one of the arteries leading to your head. The contrast material makes the arteries look bright white on x-rays. The outlines of the arteries and any aneurysm will show up clearly. Angiography can be done in the CT scanner (CT Angiography) or by puncturing the artery in the groin, advancing a catheter, and then injecting the contrast material.

  • Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) are also used in detection of aneurysms.


  • If rupture occurs, about ½ of the patients survive. The best predictor of risk of rupture is the size of the aneurysm.

  • A guide to the likely outcome (prognosis) is determined by the patient's level of consciousness and neurologic problems when first examined upon arrival to the hospital.

After a rupture of an intracerebral aneurysm, the following may occur:

  • The cerebral blood vessels get smaller in size (cerebral vasospasm). This can decrease the blood supply to parts of the brain, causing a stroke.

  • Re-bleeding from the aneurysm.

  • Swelling of the ventricles in the brain (hydrocephalus).

  • Seizures (convulsions).

  • Rupture of an aneurysm can also affect heart and lung function. If these problems develop, they are assessed and treated.

All patients are monitored for the possible development of these problems. Treatment varies depending on what complications do or do not develop.


  • Treatment of aneurysms is done with either conventional surgery or by an endovascular procedure.

  • Timing of treatment is an important factor in the prevention of complications. Successful early treatment of a ruptured aneurysm (within the first 3 days of a bleed) helps to prevent re-bleeding and vasospasm.

  • In some cases, there may be a reason to treat later (10-14 days after a rupture). Many things are considered when making this decision. These include an assessment of how much brain swelling is present. Each case is handled individually.


Treatment of an aneurysm that is causing no problems (asymptomatic aneurysm), but was discovered by chance is complex. Many things must be considered. These include the size and exact location of the aneurysm. Small aneurysms in certain locations of the brain have a very low chance of bleeding or rupturing. Other things to consider are the patient's age, overall health, and their feelings and personal preferences. Each individual case is different. In general, if someone has an aneurysm that has not bled in the past, the risk of an operation is greater than the risk of watching and monitoring. In those cases, the risk of an operation increases as the patient gets older. Surgery is usually recommended for large, easy to reach surgically, unruptured aneurysms. Again, each case must be assessed individually.