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Each year, nearly half a million people worldwide die from brain aneurysms. In the U.S., an estimated 6.7 million people have an unruptured brain aneurysm, which means about 1 in 50 people might have one.

A brain aneurysm, also called a cerebral aneurysm, is a bulge or ballooning in a blood vessel in the brain. Dr. Chris Fox, a Mayo Clinic neurosurgeon, says there are two broad categories of aneurysms: ruptured aneurysms, which are neurosurgical emergencies, and unruptured aneurysms, where there is time to establish a treatment plan that may involve multiple options.

"For unruptured aneurysms, we have the ability to plan and make a decision on the best treatment upfront in a nonemergent situation," says Dr. Fox.

But when a ruptures, prompt medical attention is required.

"Typically, when we see a patient with a , we treat it as quickly as possible. That's usually within a matter of hours because there's a risk that the aneurysm can rerupture," he says.

Symptoms

Symptoms of a ruptured aneurysm can include severe head pain, nausea, vomiting, confusion and loss of consciousness.

"The classic presentation for a ruptured aneurysm is a patient has the worst headache of their life," Dr. Fox says.

Brain aneurysms are more common in women, and there may be a because aneurysms can run in families.

"But smoking and are two of the biggest risk factors for causing an aneurysm or having an aneurysm form," says Dr. Fox.