Brain Aneurysm

Most people with brain aneurysms won't experience symptoms until the aneurysm bursts and causes a hemorrhage. The most common scenario is for the brain aneurysm to rupture during physical exertion or stress, but it can happen at any time of day, under any circumstances.

Typically, the patient will experience a sudden, severe headache. Unfortunately, the headache is often not recognized as being related to a brain aneurysm by patients or physicians. There may also be nausea, vomiting, neck pain and loss of consciousness. In some cases, the blood which leaks into the spinal fluid may circulate down the spine and cause severe pain in the lower back and in both legs. Some brain aneurysms are quite large, and may press on the surrounding brain or on the nerves. When this occurs, it can cause the eyelid to droop and the pupil to enlarge.

There are also some aneurysms that contain a blood clot within them, and this increases the potential for stroke. However, this is quite uncommon. Occasionally, an enlarging brain aneurysm can cause symptoms through the compression of surrounding neurologic structures (e.g., visual changes, seizures and facial pain). Unfortunately, symptoms frequently do not appear until the aneurysm has ruptured (bled). The rupture of a brain aneurysm is usually sudden and occurs without any warning. Symptoms of a ruptured brain aneurysm may include loss of consciousness, severe headache with nausea or vomiting, stiff neck, difficulty moving any part of the body, numbness or decreased sensation in any part of the body, blurred vision, drooping eyelids, seizure and/or a change in mental status (such as a person becoming extremely lethargic).

Once a brain aneurysm ruptures, blood accumulates between the brain and the subarachnoid space (a thin wall surrounding the brain), resulting in a subarachnoid hemorrhage (SAH). As blood collects in this space, it compresses and damages the surrounding brain tissue. The tissue injury causes the surrounding blood vessels to be susceptible to vasospasm (an abnormal constriction of the blood vessels of the brain, which can result in additional tissue damage through diminished blood flow to the brain). The combined effect of bleeding and vasospasm can result in serious neurologic impairment or even death.

Screening for brain aneurysms before they rupture is extremely important, because once a rupture occurs the prognosis is poor. However, treating a brain aneurysm that's been detected early is quite possible, and can usually be done with little risk. Even if we do detect an aneurysm in its early stages, we have no way of predicting its risk of future bleeding. However, it appears that the size of the aneurysm is an important factor in the risk of future bleeding, as smaller ones are less likely to bleed.

We strongly recommend screening for individuals who are at high risk. If you have two first-degree relatives (parents, siblings and children) who have brain aneurysms, the chances are about 1 in 10 of finding an aneurysm prior to bleeding. Occasionally, screening may be recommended for persons who have only one family member with a brain aneurysm. To discuss your options contact the main switchboard: (310) 4-CEDARS (423-3277)

There are three commonly-used techniques for diagnosing the presence of a brain aneurysm: angiography, MRI angiography, and spiral CT (CAT) scans.

• Conventional angiography is the method of choice for detecting a brain aneurysm. A dye, which is visible on x-rays, is injected in an artery that supplies blood to the brain. The dye will follow the path of the brain's blood flow, and show any obstructions or leakage.

• An MRI scan is another method, and is especially useful for detecting the presence of a blood clot within a brain aneurysm.

• A CT scan (CAT scan) can detect bleeding in the artery after the aneurysm has burst. Occasionally, the CT scan will appear normal, and if a subarachnoid hemorrhage is still suspected, a sample of spinal fluid would be examined for the presence of blood.

The ultimate goal of brain aneurysm treatment is to prevent any future bleeding while preserving the artery from which the brain aneurysm originates.

Currently, there are two major treatments:

The placement of a metal clip across the base of the expanded, balloon-like aneurysm is the most definitive treatment, and the success rate is excellent. Over the last 20 years, surgical techniques for repairing brain aneurysms have improved tremendously, and "microsurgical clipping" can be carried out with very little risk.

Some aneurysms however, cannot be safely clipped and require more sophisticated surgical techniques such as vascular bypass grafting, whereby a vein is taken from the leg and hooked up between an artery in the neck and an artery in the brain.

Very rarely, the patient's heart has to be stopped and the body cooled down in order to treat an aneurysm safely.

Endovascular therapy treatment of brain aneurysms is emerging as a promising alternative to microsurgical clipping. Endovascular therapy involves the placement of small metal coils within the aneurysm. These coils cause the aneurysms to clot and solidfy and prevent further bleeding. This is still an experimental treatment, and early experience suggests that it is safe and effective . But the long-term consequences have not yet been evaluated.

Brain Aneurysm Causes

---

Brain aneurysms have no one single cause, but there are several risk factors that can contribute to brain aneurysms. These factors can be divided into genetic and environmental factors:

Genetic Factors:

Although people are not born with brain aneurysms, there is considerable evidence that there are some genetic factors involved. Brain aneurysms often run in families. Recent studies have shown that about 1 out of 5 patients with ruptured brain aneurysms will have a close family relative who's also had one. Research also shows that brothers, sisters, children and parents of a patient with a ruptured brain aneurysm are about four times more likely to have a brain aneurysm than the general population. It's also interesting to note that compared to brain aneurysms in the general population, those that occur within a family are smaller when they burst, burst at a younger age, and are more likely to be followed by the development of a new brain aneurysm.

Several specific genetic disorders have been identified which are associated with an increased risk of developing a brain aneurysm. The most common is polycystic kidney disease. Others include Ehlers-Danlos syndrome type IV, neurofibromatosis type I and Marfan syndrome. It is not unusual for a patient to be completely unaware of having one of these genetic diseases until the brain aneurysm occurs.

Environmental Factors:

Environmental factors are important in the development of brain aneurysms. One way that we've determined this is that brain aneurysms are extremely rare in children, and the risk of a ruptured brain aneurysm increases with age until at least age 80. This suggests that exposure to the environment over the years has an impact.

Of the various environmental factors, the primary culprit is cigarette smoking. Smokers are about 3 to 10 times more likely to have ruptured brain aneurysms than non-smokers, and the risk increases with the number of cigarettes smoked. Patients who continue to smoke after a ruptured brain aneurysm are at high risk for developing another aneurysm. High blood pressure has been extensively studied as a risk factor, and although it does pose an increased risk, it is less of a risk than cigarette smoking.

Hormones:

We believe that hormones may play a role in the development of brain aneurysms. Unlike other types of strokes, women, after menopause, are more commonly affected by brain aneurysms than men. However, prior to menopausal age, it's men who are more commonly affected. Low-dose oral contraceptives do not increase the risk of a ruptured brain aneurysm, and in fact may even decrease the risk. In post-menopausal women, the use of hormone replacement therapy also appears to decrease the risk.

Alcohol:

Heavy alcohol consumption is an important risk factor for ruptured brain aneurysms, particularly with binge drinking. However, low-levels of alcohol consumption (1 or 2 drinks a day) may actually lower the risk of a ruptured brain aneurysm.

Ruptured brain aneurysm complications

---

The most important complication after a brain aneurysm has burst is the chance of it bleeding even more and not re-sealing itself. This is most common within the first 24 hours of the subarachnoid hemorrhage and the danger remains fairly high for another two weeks. It's generally recommended to treat the brain aneurysm early after it has caused a subarachnoid hemorrhage.

Once an aneurysm bursts and causes a subarachnoid hemorrhage, about 1 out of 8 patients will die before receiving any medical attention. One-half of patients die within one month after the brain aneurysm bursts, and of those who do survive, less than 1 in 3 will be able to live normal lives.

The Maxine Dunitz Neurosurgical Institute

---

Offering a complete range of brain aneurysm treatments. To discuss your options contact the main switchboard: (310) 4-CEDARS (423-3277)

Back to Top

---

---

1111

Content Last Updated on Feb. 5, 2003
© Copyright  2000-2001 Cedars-Sinai Health System. All rights reserved.
Terms and Conditions