Brain aneurysms can be similar to heart attacks. Just like a person may have no warning of an impending heart attack, there almost is never a warning that a brain aneurysm is about to rupture. Fortunately, through imaging screening techniques, individuals at high risk of harboring a brain aneurysm can be identified easily with non-invasive imaging tests.
Risk factors for developing brain aneurysms include cigarette use, disorders of the body’s structural proteins (Ehlers-Danlos syndrome, Marfan syndrome), fibromuscular dysplasia, chronic hypertension, history of cerebral aneurysms in closely related family members, use of cocaine, crack or amphetamines and polycystic kidney disease.
Screening in the setting of a family history of fusiform aneurysm:
In the case of a first degree relative with a known intracranial fusiform aneurysm, it is unclear if screening is recommended, but there are several reports of fusiform aneurysms occurring in a family. Some doctors would recommend screening.
Screening in the setting of a family history of saccular aneurysm:
If one member of the family is known to be affected with saccular aneurysm, then screening of other family members is not clearly recommended since the occurrence of an aneurysm with screening is approximately the same or only slightly higher than the general population. This is a somewhat controversial issue, and family members will understandably not infrequently ask to be screened, and screening with either brain MRA or brain CTA could readily be performed if that would be their preference. It is important that the patient understands the potential implications of screening should an aneurysm or some other unexpected finding be detected (i.e., life and health insurance issues, etc.). Even in the setting of only one affected member of the family, some doctors do recommend screening of first degree relatives (siblings, parents, children), and there are some data, (unpublished at this point) which suggest that the occurrence in these first degree relatives may be higher than previously thought.
If two or more members of the family are affected with brain aneurysms, then aneurysm screening (with brain MRA or brain CTA) is usually recommended for at least the first degree relatives over the age of 25 of those affected. Our recommendation is for any individual who has two or more relatives (e.g. mother, father, brother, sister, aunt, uncle, grandparent, cousins) with a brain aneurysm be screened for aneurysms starting in their twenties and then every 5 to 10 years thereafter. It is thought that patients with a family history of aneurysm may develop them at a younger age in subsequent generations. Those with a family history of aneurysms are more likely to have multiple aneurysms and those aneurysms are more likely to rupture at a smaller size. The risk of aneurysm detection in these family members is increased in women, those with hypertension, and in cigarette smokers. If your family has a history of aneurysms, it is imperative for you to be screened by MRA or CTA when you are in your twenties. Early detection saves lives as aneurysms most often times can be treated.
Two quick and safe ways to screen for aneurysms include MRI with MRA (Magnetic Resonance Imaging with angiography) and CT with CTA (Computed Tomography with Angiography). Images that are obtained during these studies will reliably detect aneurysms as small as 2 mm. There are advantages and disadvantages of each of these types of studies.
MRA images are generated as a result of disturbances in a strong magnetic field. Excellent pictures of the brain itself are obtained and reasonably good pictures of the major arteries are as well. This is a good way to do an initial “screen”. These are very safe tests as no radiation is used, but the quality and detail of the images are not as good as CTA or catheter angiography. In addition, it might take as long as 40 minutes for a patient to complete one of these studies, and patients who are claustrophobic frequently need to be sedated, as the confines of the machine induce a sense of claustrophobia.
CTA images are created by injecting an iodine-based dye into the vein of the arm. As it passes from the vein to the heart and then pumped to the brain, X-rays are passed through the head and images are created. This is a very fast test that takes only a few minutes to perform and the quality and detail of the images are excellent. The down side is that it does expose the patient to X-ray radiation and iodine which in some patients can lead to an allergic reaction. Usually, CTA is reserved as a follow-up study to a MRA study if an aneurysm is detected and there is a need to collect more information on the aneurysm. This additional information allows for a more detailed conversation with the physician on the need for treatment and what type of treatment options are available.
Catheter-based angiography is not a good initial test for screening as the small risk of this procedure does not justify its use when MRA and CTA are effective in this role.