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What is a brain aneurysm?
A brain aneurysm is a bulge in the wall of an artery inside or near the brain. This usually happens because part of the blood vessel wall is weak, which lets blood fill up in a balloon-like pouch. Most aneurysms have no symptoms or cause no problems.
But in some cases, the wall of the aneurysm becomes too thin and the pouch can burst. This ruptured brain aneurysm causes bleeding around the brain and can cause symptoms like a severe headache. It can cause brain damage and be life-threatening. It requires immediate treatment at the ER.
Fortunately, a brain aneurysm that bursts is very rare. But aneurysms happen to about 1% to 2% of all people.
Most common symptoms
If you have a headache, there is an overwhelming chance that it is not due to an aneurysm. Headache from a ruptured aneurysm is very characteristic: it is sudden, severe, described as a “thunderclap,” and is often associated with nausea and vomiting. —Dr. Brian Walcott
The vast majority of brain aneurysms have no symptoms at all. They usually only cause problems or symptoms if they burst, or if they become so large that they press on nerves near the brain.
If an aneurysm bursts, it will cause a severe and sudden headache that does not get better. People often describe it as the “worst headache of their life.”
Neck stiffness and sensitivity to bright lights are also common symptoms. Sometimes, people get drowsy along with the headache. If the bleeding is very bad, it can cause someone to have trouble breathing or fall into a coma (become unconscious).
- Sudden and severe headache
- Nausea and/or vomiting
- Sensitivity to light
- Neck stiffness
Other symptoms you may have
If the aneurysm does not burst but grows large enough to press on nerves (which is rare), you may have:
- Double vision
- Blurry vision
- Difficulty with balance and walking
There are a few things that feel similar to an aneurysm rupture, such as very bad tension-type headaches or migraines. Even a sinus infection can sometimes cause a headache that is similar to an aneurysm rupture. Rarely, meningitis (inflammation in the brain and spine) can also cause similar symptoms.
If you normally get headaches or migraines, you wouldn’t go to the ER unless a headache felt very different or a lot more intense than your typical headache.
If a severe headache—the worst of your life—hits you very suddenly, call 911 or go to the ER immediately. If it is a brain aneurysm, immediate medical attention is needed to help prevent life-threatening complications.
At the hospital, it is especially important to be screened for a brain aneurysm if you have two or more first-degree relatives (parents, siblings, or children) who have had one.
Brain aneurysm treatment
Many people think that all aneurysms need to be repaired. For small aneurysms, sometimes the safest thing to do is to observe them, since the risk of bleeding is very close to zero. —Dr. Walcott
If you have symptoms of an aneurysm that’s pressing on a nerve, or if one shows up unexpectedly on a brain scan (like for a concussion), there are several treatment options or you may take a wait-and-see approach. If an aneurysm ruptures, it is almost always repaired with surgery to prevent another episode of bleeding.
If you have a small aneurysm that is not likely to burst, your doctors will want to see you periodically for observation, to keep track of the aneurysm’s size. You probably will not need surgery.
If the aneurysm is at a high risk for bursting, you might need a procedure to repair the blood vessel and prevent bleeding. One option is surgery to open the skull (craniotomy for aneurysm clipping). Another is a procedure where the doctor will go inside the blood vessel to repair it (endovascular coiling or stenting).
- Craniotomy. The surgeon will repair the aneurysm by using a microscope to place a clip across the bottom of the bulge to seal it off. The surgery is done under general anesthesia and you will stay in the hospital for a few days after the surgery. Most people feel a mild to moderate headache afterward, and they are given pain medication for it. You might have some swelling in the scalp and around the eye during the healing process. This will get better with time.
- Endovascular repair. To repair the aneurysm, the surgeon will place metallic coils or a metallic mesh basket inside of the aneurysm. Sometimes it’s repaired with a stent that redirects blood flow away from the aneurysm. Every aneurysm and every person is different. You’ll just stay in the hospital one night after the procedure.
If an aneurysm ruptures, it is almost always repaired with surgery to prevent another episode of bleeding. You can expect to be in the hospital for about two weeks. The doctors will want to monitor you since you will be at a high risk for delayed stroke complications.
There are no specific medications to make an aneurysm smaller or keep it from bursting. If your doctor suggests endovascular repair, you may be required to take blood thinners afterward to prevent clotting and stroke. These may include aspirin or prescription blood thinners such as clopidogrel (Plavix), prasugrel (Effient), or ticagrelor (Brilinta).
Follow-up depends on the type of brain aneurysm and treatment. If the aneurysm is small and the doctors decide to monitor it, they’ll probably suggest you get MRI or CT scans annually or every other year. Sometimes they will want to do a test called an angiogram—essentially an X-ray movie of blood flow in the brain—to get the most detailed picture possible.
If you have had treatment for an aneurysm, you’ll need follow-up to make sure it doesn’t grow back. This follow-up can include MRI scans, CT scans, or an angiogram.
What can cause a brain aneurysm?
There are actually two new ways to treat aneurysms that have been approved by the FDA in recent years: flow diverting stents and intrasaccular flow diversion. —Dr. Walcott
Doctors don’t know what exactly causes a brain aneurysm, but they seem to be more common as we get older. That suggests that aneurysms develop over time, probably from a weakness in the wall of a blood vessel.
Since there is high pressure from blood flow inside your arteries (compared with lower pressure in veins), a small spot of weakness in the wall of an artery can make that area bulge out.
Researchers are still looking for answers about who is most at risk for a brain aneurysm, and who is at risk for having an aneurysm burst. Aneurysms are much more common in people who smoke cigarettes or have high blood pressure. Smoking raises blood pressure and high blood pressure puts more stress on the walls of your arteries.
But brain aneurysms do sometimes happen to people who don’t smoke and who have healthy blood pressure levels.
Brain aneurysms are also more commonly found in people with polycystic kidney disease. Very rarely, aneurysms can occur frequently in families, so there might be a genetic link.
Doctors don’t know how to prevent a brain aneurysm. But they do know that cigarette smoking and high blood pressure are two of the biggest risk factors seen in research studies.
You can lower your risk of developing an aneurysm by quitting smoking and getting your blood pressure to a healthy level.
Dr. Walcott is a dual fellowship trained neurosurgeon that specializes in neurovascular disease. His clinical interests are in the management of patients with stroke, brain aneurysms, arteriovenous malformations, cavernous malformations, carotid artery disease, moyamoya disease, brain tumors, and spinal cord tumors. He performs both surgery and minimally invasive, endovascular procedures.
Dr. Walcott received his undergraduate degree from Seton Hall University. He then went on to graduate from medical school at Loyola University Chicago, where he was inducted into the Alpha Omega Alpha honor society. He completed a residency in neurological surgery at Harvard Medical School & the Massachusetts General Hospital. Following residency, Dr. Walcott joined the faculty at Harvard Medical School as an attending neurosurgeon at the Massachusetts General Hospital. He then went on to complete a fellowship in neurovascular surgery at the University of California San Francisco, with an emphasis on cerebrovascular bypass and minimally invasive skull base surgery. Additionally, he completed a fellowship in endovascular neurosurgery at the University of Southern California. His research interests are focused on investigating the genetic and molecular basis of vascular malformations, brain edema, and cerebral ischemia. He has authored over 150 peer-reviewed scientific publications and his research been funded by the Brain Aneurysm Foundation, the Congress of Neurological Surgeons, and the National Institutes of Health. Dr. Walcott is a member of the American Association of Neurological Surgeons, the Congress of Neurological Surgeons, and the Society of Neurointerventional Surgery.