Brain Aneurysm
(Cerebral Aneurysm)

What Is It?

A brain aneurysm, or cerebral aneurysm, is an abnormal bulging out of the wall of a blood vessel that brings blood to the brain. Over time, the blood pressure inside the aneurysm can lead to expansion and eventual rupture of the aneurysm.

There are probably several reasons that a brain aneurysm can develop but one of the most commonly cited is high blood pressure. Because the wall of the aneurysm is under pressure, it gets thinned out and can be prone to bleeding. While aneurysms can occur any time in life, the majority of them present in late adulthood.

Aneurysms of the brain blood vessels are not uncommon, but many people have then and never know it. For some percentage of people with aneurysm, the aneurysm leads to symptoms or ruptures, bringing it to medical attention.

When a brain aneurysm ruptures, the most common effect is something called subarachnoid hemorrhage. The subarachnoid space is a fluid-filled space between the arachnoid membrane, one of the coverings of the brain and spinal cord, and the surface of the brain. Because the blood vessels to the brain run through this area, when an aneurysm ruptures, it typically bleeds into this space, spreading out through the cerebrospinal fluid.

What Types of Symptoms Are Typical?

The most common presentation of a brain aneurysm is rupture, causing subarachnoid hemorrhage. The classic presentation of this bleeding is a sudden onset of a severe, excruciating headache. Patients often describe it as the "worst headache of my life" and say it is unlike any other headaches they have had. I comes on quickly and is often described as a severe stabbing or shock-like pain.

The headache can be accompanied by other signs of irritation of the nervous system including stiff neck, pain with bright lights, nausea and vomiting. In severe cases, hemorrhage can lead to a depressed level of consciousness, coma or even sudden death. In fact, a significant percentage of victims of a ruptured brain aneurysm died before getting to the hospital.

Occasionally, the aneurysm itself can cause symptoms if it pushes on nervous system structures as it grows. This can lead to various abnormalities depending on the location of the aneurysm.

How Is The Diagnosis Typically Made?

Many brain aneurysms first present themselves when they rupture, presenting with sudden onset of severe headache, neck stiffness, and/or depressed level of consciousness. This presentation usually leads to work-up with a CT scan which can reveal the subarachnoid blood. In some cases where CT is either not available or does not show any obvious blood, a lumbar puncture (spinal tap) is performed to obtain cerebrospinal fluid to analyze it for blood or blood breakdown products. This involves inserting a small needle into the spinal canal through the low back to remove a small amount of cerebrospinal fluid.

In some patients, a brain aneurysm may be diagnosed prior to rupture. This can happen incidentally. For example, if a patient is having headaches or some other unrelated symptom that prompts a CT scan or MRI scan, the aneurysm may be found on that scan. Some aneurysms that are causing neurological symptoms may also prompt one of these neurological tests which reveal the aneurysm.

In either case, the definitive diagnosis of a cerebral aneurysm is usually confirmed on some form of cerebral angiogram. A traditional angiogram involves placing a catheter through an artery in the leg up into an artery that supplies the brain. Contrast dye which can be seen on x-ray is then injected to visualize the blood vessels in the head while x-rays are taken. This allows a very detailed analysis of the anatomy of the brain blood vessels and can reveal an aneurysm as well as other forms of cerebrovascular disease such as an arteriovenous malformation.

Some hospitals now use a less invasive form of angiography called a CT-Angiogram. In this study, contrast dye is simply injected into a normal vein IV and a CT scan of the head is performed at the same time. This allows visualization of the blood vessels as well and a three dimensional reconstruction can be viewed on a computer to see the detailed anatomy of the brain's blood supply.

What Are Some Common Treatments?

Treatment for a brain aneurysm is highly variable, depending on the type and location of the aneurysm, whether it has ruptured or not and details of the patient's condition. Each case should be evaluated by that patient's own physicians to determine the best course of action.

That being said, there are generally a few options for treatment of an aneurysm. Aymptomatic, unruptured aneurysms are sometimes just watched. Alternatively, they may be treated as described below. Again, this decision is made by the patient while discussing the appropriate options with their physician.

In the case that treatment is planned for a ruptured or un-ruptured aneurysm, there are generally two primary forms of treatment for most basic aneurysms, although some special cases may require other types of treatment. For ruptured aneurysms, treatment is generally recommended if the patient's condition is stable to help prevent re-bleeding, which can occur in the acute period following a bleed.

The traditional way to treat an aneurysm is by a surgery called clipping. The aneurysm is exposed through an opening in the head. The base of the aneurysm, where it bulges off of the normal blood vessel, called the aneurysm neck, is clipped with a special metallic device called an aneurysm clip. This closes the opening into the aneurysms so that blood cannot get into the sac. This clip is left in place permanently. If properly place, it prevents any further enlargement or rupture of the aneurysm.

A newer treatment, called coiling, can be done without an open surgical procedure. It is an endovascular treatment which means that it is performed completely from within the blood vessel. A catheter is placed into a large artery, usually in the leg, and a small catheter is maneuvered up into the head and into the aneurysm. Tiny metallic coils are then deployed into the aneurysm which slowly fill the aneurysm from the inside. This is aimed at causing occlusion of the aneurysm so that blood cannot enter it.

There is much debate about which treatment for cerebral aneurysm is best, surgical clipping or endovascular coiling. Both have some advantages and disadvantages so no generalization can be made about which is best in all cases. The decision for each patient is made individually based on the specifics of each case and a discussion of the patient or patient's family with their treating physicians.

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Important Note: This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.

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