What Is a Brain Aneurysm? | Keck Medicine of USC

What Is a Brain Aneurysm?

Being diagnosed with a brain aneurysm is serious — and more common than one might think. Here’s what you should know about this condition and who’s at risk.

Just hearing the word “aneurysm” can trigger concerns and many questions. But knowing more about them and if you’re at risk can empower you to make the right decisions for your health.

A brain aneurysm is a weakness in a blood vessel in the brain. Blood collects in this weak spot, causing the blood vessel to enlarge.

Unfortunately, brain aneurysms themselves are asymptomatic. You can lead a normal life and not even know you have a brain aneurysm — in fact, one in 50 people have an unruptured brain aneurysm.

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However, as the vessel continues to increase in size, you could experience symptoms caused by the enlarged vessel pressing against nerves in the brain. Speak with your doctor if you experience these warning signs:

  • Headaches
  • Dilated pupils
  • Blurred vision
  • Facial numbness

In more serious cases, the affected blood vessel weakens and balloons. This can cause a leak or rupture, leading to a subarachnoid hemorrhage, also known as bleeding in the brain.

A ruptured brain aneurysm occurs in about one out of 30,000 people every year in the United States. It’s a serious condition: 40% of ruptured brain aneurysms are fatal, and 66% of patients who survive a rupture experience permanent neurological impairment.

What are the warning signs for a ruptured brain aneurysm?

When a brain aneurysm ruptures, blood leaks out of the blood vessels and into the surrounding membrane, triggering a severe headache. Immediately seek medical attention if you have one or all of these systems:

  • Loss of consciousness
  • Drowsiness
  • Loss of balance
  • Dilated pupils
  • Sensitivity to light
  • Blurred vision
  • Diminished mental awareness
  • Seizure
  • Nausea and vomiting

“The classic presentation is the worst headache of your life. They call it a ‘thunder clap’ headache,” says Jonathan J. Russin, MD, an assistant professor of clinical neurological surgery at the Keck School of Medicine of USC and neurosurgeon with USC Neurosciences at Keck Medicine of USC.

Russin explains this may be preceded by a smaller bad headache, sort of like the foreshock to the bigger event. “There is something called a sentinel hemorrhage, where people will have a really quick onset of a bad headache where they don’t necessarily pass out but may experience nausea or vomiting. But generally that’ll happen a couple of weeks before they have their big hemorrhage, and it’s only generally in retrospect that you pick it up.”

Who is at risk?

A brain aneurysm occurs where there is weakness in the blood vessels, usually where these blood vessels divide or branch off. A few causes known to weaken blood vessels and increase your risk for an aneurysm include:

  • Family history of brain aneurysms
  • Aging, with those over 40 at a higher risk
  • Gender – more women than men are reported to have brain aneurysms
  • Smoking
  • High blood pressure
  • Head injury

Even if none of these risk factors apply to you, it’s best to be on guard if you exhibit the aforementioned symptoms. According to Russin, being predisposed to an aneurysm doesn’t necessarily mean that you’re going to have one, and you can still have an aneurysm if you don’t carry any of those risk factors — it could just be bad luck.

Can a brain aneurysm be treated?

Yes. Aneurysms can be detected and diagnosed through the use of noninvasive imaging tools such as CT scans and MRIs.

An unruptured aneurysm can be treated with blood pressure medication and surgical procedures to prevent a future rupture. High blood pressure and stimulants can cause an aneurysm to burst. If an aneurysm ruptures, options include surgery or an endovascular approach to reduce or block the flow of blood into the area of the aneurysm.

by Heidi Tyline King

If you think you might be at risk or are experiencing symptoms of a brain aneurysm, consult the experts at Keck Medicine of USC. If you are in the Los Angeles area and are looking for exceptional care, schedule an appointment by calling  (800) USC-CARE (800-872-2273) or visiting https://neuro.keckmedicine.org/request-an-appointment/.