Dr. Aaron Cohen-Gadol is a neurosurgeon with Methodist Hospital and the Indianapolis Neurosurgical Group.

Question: How common are brain aneurysms?

Answer: About 1 to 2 percent of the population suffers from brain aneurysms. There are familial forms of aneurysms. Brain aneurysms most commonly occur in people age 50 and older. It can happen in younger people, especially the familial form.

Q: What is a brain aneurysm?

A: A brain aneurysm is a weakening in a blood vessel’s wall that eventually causes an out-pouching or ballooning at one of the branches of the blood vessels in the brain. This out-pouching harbors a thin wall and can rupture and hemorrhage into or around the brain.

Q: What are the symptoms?

A: A severe headache. People commonly say it’s the worst headache of their life. People may pass out, have nausea, vomiting. Up to 30 to 40 percent of people die on the spot after their hemorrhage.

Q: Can this be treated for people who do not die on the spot?

A: It can be treated as long as it is diagnosed. Any ruptured aneurysm should be treated.

One treatment is an endovascular technique. Platinum coils are placed into the aneurysm through a catheter that is placed in the vessels of the body.

The other way is by brain surgery, where you place a clip across the aneurysm, so there is no more blood flow through it.

Q: Do all aneurysms require treatment?

A: Aneurysms present in two forms. Number-one is a hemorrhage. If it’s hemorrhage, it can re-bleed, so we like to treat it within 24 hours. A rehemorrhage would likely cause death. If it has not hemorrhaged, there’s no urgency to treat.

Q: What symptoms will you have if it has not hemorrhaged?

A: Headaches, visual difficulties, double vision, balance difficulty — but those are rare.

Most commonly, these aneurysms are found because the patient had an MRI for another reason — like regular headaches. If the aneurysm is less than seven millimeters, treatment has to be individualized, but most commonly we observe it.

Q: What can a person do to lower his or her risk of developing an aneurysm?

A: Avoid smoking, keep blood pressure under control and live a healthy life. If they have two first-degree close family members who have a history of known aneurysms, they should undergo imaging.