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

"A proportion of these patients will go on to have a rupture. And the challenge with rupture is that it's unpredictable."

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

"The typical presentation is somebody who has the worst headache of their life."

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.