Vivien Williams: An aneurysm is an abnormal bulge or ballooning in the wall of a blood vessel.

Bernard Bendok, M.D., Neurosurgery, Mayo Clinic: A portion of these patients will go on to have a rupture. And the challenge with rupture is that it's unpredictable.

Vivien Williams: Dr. Bernard Bendok says a ruptured aneurysm is a medical emergency that can cause life-threatening bleeding in the brain.

Dr. Bendok: The typical presentation is somebody who has the worst headache of their life.

Vivien Williams: Fast treatment is essential. It includes open surgery or less-invasive options, such as sealing the ruptured artery from within the blood vessel with metal coils and/or stents.

Dr. Bendok says 1 to 2 percent of the population have aneurysms and only a small percentage of that group will experience a rupture. People who have a family history of aneurysms, have polycystic kidney disease, connective tissue disease, and people who smoke are at increased risk of rupture and should consider screening. If a rupture happens, fast treatment can save lives.

For the Mayo Clinic News Network, I'm Vivien Williams.