A brain aneurysm is an abnormal bulge in a brain artery that develops where the blood vessel wall is weakened. About 1.5 to 5 percent of the general population has or will develop a cerebral aneurysm.
That’s about 3 to 5 million people in the United States, but most don’t show any symptoms. A small percentage may suffer from bleeding.
However, an aneurysm can produce symptoms as it enlarges, including headaches or localized pain. If an aneurysm gets very large, it may produce pressure on the normal brain tissue or adjacent nerves. This pressure can cause difficulty with vision, numbness or weakness of an arm or leg, difficulty with memory or speech, or seizures.