Brain Aneurysm

Medically Reviewed by Nayana Ambardekar, MD on September 18, 2022
7 min read

brain aneurysm is a weak spot in the wall of a blood vessel inside the brain that can sometimes burst and cause a subarachnoid hemorrhage (SAH).Think of a weak spot in a balloon and how it feels stretched out and thin. A brain aneurysm is like that.

That area of the blood vessel gets worn out from constant flow of blood and bulges out, almost like a bubble. It can grow to the size of a small berry. There are different types:

Saccular aneurysms are the most common type of brain aneurysm. They bulge out in a dome shape. They’re connected to the artery by a narrow “neck.”

Fusiform aneurysms aren’t as common as saccular aneurysms. They don’t pouch out in a dome shape. Instead, they make a widened spot in the blood vessel.

Although brain aneurysms sound alarming, most don’t cause symptoms or health problems. You can enjoy a long life without ever realizing that you have one.
But in rare cases, aneurysms can grow big, leak, or explode. Bleeding in the brain, known as a hemorrhagic stroke, is serious, and you’ll need medical care right away.

The type of symptoms you have from a brain aneurysm depend on whether it ruptures or not.

Ruptured brain aneurysm symptoms

You need emergency care if you suddenly get an intensely painful headache, lose consciousness, or have any of these other symptoms of an aneurysm rupture:

  • Intense headache that comes on suddenly
  • Loss of consciousness
  • Nausea and vomiting
  • Drowsiness
  • Loss of balance in things like walking and normal coordination
  • Stiff neck
  • Dilated pupils
  • Sensitivity to light
  • Sudden blurred or double vision
  • Drooping eyelid
  • Confusion or trouble with mental awareness
  • Seizure

Although brain aneurysms usually don’t show symptoms, they can press on the brain and nerves as they get bigger.

Unruptured brain aneurysm symptoms

See a doctor at once if you’re having a new headache or pain above or behind your eye. Call 911.  Other symptoms of an unruptured aneurysm are:

  • Dilated pupils
  • Blurred or double vision
  • Drooping eyelid
  • A hard time speaking
  • Weakness and numbness in one side of your face

A sudden and intense headache can also be a sign you have a leaking aneurysm (sentinel bleed). This can be a warning sign you’ll soon have a full rupture.

Brain aneurysms usually develop as people age, becoming more common after 40. It’s also possible to have a blood vessel defect at birth.

Women tend to have higher rates of aneurysms than men.

Aneurysms tend to form at the fork of blood vessels, places where they branch off, because those sections tend to be weaker. They are most commonly found at the base of the brain.

If your brain aneurysm ruptures or leaks and causes a hemorrhagic stroke, you’ll need medical treatment right away. This is rare but can be life-threatening.

Your doctor usually won’t know why your brain aneurysm ruptured. But experts know a few reasons that could heighten your risk of bleeding:

High blood pressure. This is the most common factor that leads to a ruptured brain aneurysm.

Heavy lifting or straining. Your brain aneurysm may rupture because of pressure from lifting or straining.

Strong emotions. If you’re very upset or angry, this can raise your blood pressure and lead to a ruptured aneurysm.

Medications. Blood thinners including warfarin (Coumadin, Jantoven) and other medicines or prescription drugs, such as diet pills like ephedrine and amphetamines, can cause an aneurysm to bleed.

Illegal drugs. Harmful drugs, like cocaine, can cause your aneurysm to rupture.

Smoking and high blood pressure are the things that put you at the most risk of having a brain aneurysm. But several other things in your medical history and lifestyle also increase your odds.

Medical history

Things in your medical history that can play a role include:

  • High blood pressure
  • Atherosclerosis, a disease in which fat builds up inside the walls of your arteries (blood vessels that deliver oxygen-rich blood throughout your body)
  • Diseases affecting your blood or blood vessels:
  • Injury or trauma to your head
  • Infection
  • Cancer or tumors in your head and neck
  • Abnormalities at birth, such as tangled blood vessels in your brain, abnormally narrow aorta (coarctation of the aorta), or cerebral arteriovenous malformation (brain AVM)
  • Family history of brain aneurysms


Rarely, kids under 18 can have a brain aneurysm. Boys are eight times more likely to get them than girls. Of the few cases in children, about 20% are “giant” aneurysms (larger than 2.5 centimeters).

Aneurysms in kids can come on for no reason. But they’re also sometimes related to:

  • Head trauma
  • Connective tissue disorders
  • Infection
  • Genetic disorders
  • Family history

Several types of scans and tests can be used to figure out whether you have a brain aneurysm. They include:

CT scan: This exam creates images of your brain. You will lie on a table that slides into a CT scanner. A technician will inject contrast dye into one of your veins to make it easier to see the blood flow and spot aneurysms in your brain.

MRI: This exam is similar in that you lie on a table that slides into a scanner. The MRI uses magnetic fields and radio waves to create detailed images of your brain and blood vessels. MRIs and CT scans can detect aneurysms larger than 3 to 5 millimeters.

The following tests are more invasive than CT or MRI scans. But they could give you and your doctors a more complete picture of what’s going on:

Angiogram: This test, considered the most reliable way to detect aneurysms, shows the weak spots in your blood vessels. During the test, you lie on an X-ray table, and you will be given something to numb any pain. Your doctor will insert a small flexible tube through a blood vessel in the leg. They’ll guide that tube, called a catheter, into the blood vessels in your neck that reach the brain. Then they’ll inject a contrast dye into you, and X-rays will be taken that show all the blood vessels in the brain. This gives your doctor a map of your blood vessels, pinpointing the aneurysm.

Cerebrospinal fluid test: Your doctor may order this test if they think an aneurysm may have ruptured.

You’ll be given something to block any pain. A technician will put a needle into you to draw spinal fluid. That fluid is tested to see whether it contains blood, which could mean an aneurysm has ruptured.

Ruptured brain aneurysm treatment

You need treatment as soon as possible if you have a ruptured brain aneurysm, because it’s likely that it will bleed again. Treatment involves stopping the blood flow into the aneurysm.

The procedures carry risks. Your doctor will figure out which treatment works best based on your health, and the size, type, and location of the aneurysm.

Surgical clipping: A section of your skull is removed to locate the aneurysm. A metal clip is placed on the opening of the aneurysm to cut off the blood flow. Your skull is then sealed shut.

Endovascular coiling: This doesn’t require surgery that opens the skull. Your doctor will insert a catheter into your groin to reach the affected blood vessel where the aneurysm is located.

The doctor will send tiny platinum coils through the tube and place them inside the aneurysm. The coils conform to the shape of the aneurysm, stopping the blood flow there. This may be safer than surgical clipping, but it has a higher chance of the aneurysm bleeding again.

Flow diverter surgery: This option is for larger brain aneurysms in which neither clipping nor coiling would work. In this procedure, your doctor inserts a stent, usually made of metal mesh, inside the artery. It becomes a wall inside the vessel to divert blood away from the aneurysm.

To help manage symptoms and prevent complications of an aneurysm, your doctor may suggest:

  • Pain relievers such as acetaminophen
  • Medications called calcium channel blockers that help prevent blood vessels from narrowing
  • Treatments to prevent a stroke, such as drugs that widen the blood vessels so blood will flow through narrowed blood vessels, or a procedure called an angioplasty that uses a small balloon to widen blood vessels
  • Anti-seizure medication
  • Ventricular or lumbar draining catheters to reduce pressure on the brain
  • Shunt surgery
  • Rehabilitative therapy to help you relearn skills you may have lost from damage to your brain

Unruptured brain aneurysm treatment

Small aneurysms that haven’t ruptured and aren’t causing symptoms may not need treatment. But this depends on your health and the aneurysm. You can talk this all over with your doctors.

A ruptured brain aneurysm can be life-threatening and lead to:

Once your doctor finds an aneurysm, it’s very unlikely that it’ll heal on its own. The good news is you can take steps to stop it from growing or leaking. There are also things you can do lower the risk of a new aneurysm:

  • Stop smoking.
  • Eat a balanced diet.
  • Work out regularly and avoid constant heavy lifting (stick with moderate exercise).
  • Don’t use cocaine or other stimulant drugs.
  • Get help for any alcohol or drug use problems.
  • Keep your high blood pressure in control with medicine and lifestyle changes.

You may never know that you have an unruptured brain aneurysm. If it doesn’t rupture, you may live your entire life without any issues. But there’s always a risk that it’ll bleed.

If this happens, you’ll need immediate medical help. The longer you wait, the worse your outcome could be. Your chances of death or disability go up as more time passes after your aneurysm ruptures.

Around 75% of people with a ruptured brain aneurysm will live longer than 24 hours. But a fourth of these people could have fatal complications within the next 6 months.

If your doctor doesn’t treat your aneurysm quickly enough you might bleed again from the same area. So, it’s important to get help as soon as possible if you think you have symptoms of a brain aneurysm.

Show Sources


Brain Aneurysm Foundation: “Brain Aneurysm,” “Warning Signs/Symptoms,” “Pediatric Aneurysm.”

U.S. National Library of Medicine -- Medline Plus: “Brain Aneurysm.”

Mayo Clinic: “Brain Aneurysm.”

National Institute of Neurological Disorders and Stroke: “Cerebral Aneurysm Fact Sheet.”

American Stroke Association: “What You Should Know About Cerebral Aneurysms.”

Cedars-Sinai: “Vasospasm.”

National Institute of Neurological Disorders and Stroke: “Hydrocephalus.”

Stanford Health Care: “Brain Aneurysms.”

UCLA Neurosurgery: “Brain Aneurysms.”

U.S. National Library of Science: “Arteries.”

National Institutes of Health, National Heart, Lung and Blood Institute: “Stents.” “Cerebral Angiography.”

Cleveland Clinic: “Brain Aneurysm.”

Johns Hopkins Medicine: “Subarachnoid Hemorrhage.”

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