Brain aneurysm bulges out of a weakened spot in an artery wall. The weakening results from an abnormal loss of the tissue making up the muscular layer of the artery. If that weak area ruptures, blood flows into the brain cutting off oxygen to brain cells, a situation that can cause permanent disability or even be fatal.
it 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.
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.
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.
In most cases, screening for a brain aneurysm occurs only after it ruptures or produces other symptoms. Otherwise, it may only be discovered during scans of the brain prescribed for other purposes. Following a subarachnoid hemorrhage, doctors may choose from several tests to confirm the presence of the aneurysm and to gain information about its nature and the best treatment option.