It’s hard not to feel paranoid about brain aneurysms. Here’s what you need to know about them.

Each time a public figure dies unexpectedly from a brain aneurysm, not only is the news upsetting and jarring, but it is also nearly impossible not to feel somewhat paranoid. After all, this fatal condition seems to occur out of nowhere.

According to the National Institute of Neurological Disorders and Stroke, a brain aneurysm (also referred to as a cerebral aneurysm) is a weak spot on an artery in the brain that balloons out and fills with blood. If the bulging aneurysm puts pressure on the nerves or brain tissue, it may rupture and spill blood into the surrounding tissue, a phenomenon known as a hemorrhage. A ruptured aneurysm can cause critical health problems, including a hemorrhagic stroke, brain damage, coma and even death.

Two doctors explain the likelihood of a scary health issue like this happening and what the risk factors are, as well as any possible warning signs.

How common are brain aneurysms?

“It’s difficult to know how common cerebral aneurysms are, as most are found postmortem, but studies estimate between 0.2% and 8%,” Dr. Karishma Patwa, a cardiologist with Manhattan Cardiology and a contributor to Lab Finder, tells Yahoo Life.

The Brain Aneurysm Foundation reports that 1 in 50 people in the U.S. has an unruptured or intact aneurysm (an aneurysm in the brain that is not bleeding). However, the annual rate of an aneurysm rupturing is much less common — it occurs in approximately every 8 to 10 per 100,000 people — and is responsible for 3% to 5% of all new strokes. Brain aneurysms are most common in adults between the ages of 30 and 60 and are more likely to affect women than men, according to the National Institute.

“Overall, the vast majority of brain aneurysms have no symptoms and do not rupture,” Dr. Michael Alexander, director of the Cedars-Sinai Neurovascular Center, tells Yahoo Life. The Brain Aneurysm Foundation also states that most aneurysms are small — about one-eighth inch to nearly 1 inch — and an estimated 50% to 80% of all aneurysms never rupture.

What typically causes a brain aneurysm?

The cause of aneurysms is multifactorial, says Patwa. “There seems to be an interaction between hypertension, coronary artery disease and a genetic predisposition to congenital diseases that are associated with vascular abnormalities,” she explains.

Alexander adds that since most ruptured brain aneurysms are spontaneous, there is not an actual cause: “Although there can be a hereditary risk, most [ruptured] aneurysms occur with no apparent genetic component.”

Patwa notes that adults with certain genetic conditions, such as lupus, Marfan syndrome, Ehlers-Danlos syndrome and polycystic kidney disease, can have a higher risk of developing a cerebral aneurysm.

“Smoking and uncontrolled high blood pressure are suspected to increase risk for aneurysm growth and rupture, but do not cause the aneurysm,” explains Alexander. Hypertension makes blood push harder against blood vessel walls, and certain circumstances — ongoing stress; a sudden burst of anger; struggling to lift, carry or push heavy objects — can raise unmanaged blood pressure levels even more and possibly result in a ruptured aneurysm, according to the Cleveland Clinic.

Other possible risk factors that can weaken artery walls and may contribute to developing a brain aneurysm include obesity, excessive alcohol consumption and illegal substance abuse (usually cocaine), says Patwa.

Are there any warning signs?

Small aneurysms that are stable in size usually do not produce any symptoms. “However, if aneurysms are growing, patients may experience sudden headaches, nausea, vomiting and loss of consciousness,” says Patwa. “Unfortunately, some large aneurysms produce no symptoms at all.”

Other possible signs of a nonruptured brain aneurysm include double vision, gradual loss of vision, a droopy eyelid on one side with an enlarged pupil or problems walking or with balance, says Alexander. “However, if an aneurysm bleeds or ruptures, the symptoms are not subtle,” he says. “A ruptured aneurysm may cause the worst headache of a person’s life — and it may last a few weeks.” It can also cause “sensitivity of the eyes to light, neck stiffness — like with meningitis — and sometimes nausea and vomiting,” he says.

Can a brain aneurysm be treated?

If a brain aneurysm is suspected, it can be diagnosed through imaging exams, such as CT scans (X-rays that can show bleeding in the brain), an MRI (magnetic resonance imaging, which creates a detailed image of the brain) and an MRA (magnetic resonance angiography, a type of MRI that examines the blood vessels), according to Brigham and Women’s Hospital. “If an aneurysm that has not ruptured is detected, treatment will focus on reducing risk of rupture and possibly surgery to prevent rupture,” says Patwa.

Whether or not an aneurysm will rupture depends on its size and location, as well as the general health of a patient, she notes. Unfortunately, both Patwa and Alexander say the prognosis for a ruptured brain aneurysm is bleak — there is a 50% to 60% chance of death, and nearly 25% of deaths happen within the first 24 hours.

If there’s a possibility that you or a loved one is experiencing a ruptured cerebral aneurysm, Patwa stresses the importance of calling 911 immediately and heading to the emergency room to undergo rapid and early imaging.

“Once diagnosed,” says Patwa, “patients will be immediately stabilized and sent for emergency surgery with either surgical clipping” — where a neurosurgeon places a metal clip at the neck of the aneurysm to stop blood flow — “or endovascular coiling” — where a catheter is threaded through a blood vessel to act as a stent to the aneurysm.