Vital Insights
An MRI for a brain aneurysm takes detailed pictures of the brain and its blood vessels. It can find a weak, bulging artery and show its size and position.
Many brain aneurysms cause no symptoms at all. They are often found by chance when a person has a brain scan for something else.
A brain aneurysm is a weak spot in the wall of an artery in the brain. Blood pressure pushes the weak spot outwards, so it bulges like a small balloon.
They are more common than most people think. A review of studies worldwide found unruptured brain aneurysms in about 3.2% of adults, roughly 1 in 30, with an average age of 50. They were about 3.4 times more common in people with an affected close relative, and about 7 times more common in people with polycystic kidney disease (Vlak et al., Lancet Neurology 2011).
Most aneurysms stay small and never cause a problem. Some grow, and a few burst. When an aneurysm bursts, blood leaks into the space around the brain. This is called a subarachnoid haemorrhage, and it is a life-threatening emergency.
Most small aneurysms that have not burst cause no signs. A larger one can press on nearby nerves and cause:
Pain above or behind one eye.
Blurred or double vision.
A drooping eyelid, or a pupil that is larger on one side.
Numbness on one side of the face.
Trouble moving one eye.
These are the main unruptured brain aneurysm symptoms. They have many other causes too, so they do not mean you have an aneurysm, but they do need a doctor's check soon.
A burst brain aneurysm is a medical emergency. The classic sign is a thunderclap headache: a sudden, severe headache that reaches its full strength within one minute. People often describe it as the worst headache of their life.
Other warning signs may come with it:
Vomiting.
A stiff neck.
Sensitivity to light.
Sudden changes in vision.
A seizure.
Fainting or confusion.
Sudden weakness or trouble speaking.
Call 108 or 112 at once. Do not wait for an MRI appointment or try to treat it at home. Some people get a smaller "warning" headache days or weeks before a major bleed, so any sudden, unusually severe headache needs urgent care, even if it eases.
An MRI uses a strong magnet and radio waves, not X-rays, to take pictures of the brain. To look at the arteries, doctors use a special MRI called MR angiography (MRA). It shows the blood vessels clearly, usually without any injection or dye, and can show an aneurysm's size, shape and exact position.
MRA is accurate. A review of studies found it detected 95% of aneurysms that were present (Sailer et al., Stroke 2014). Very small aneurysms, only a few millimetres across, are the ones most likely to be missed.
No. If a doctor thinks an aneurysm has burst, the first test is usually a CT scan, because it is fast and shows bleeding quickly. A CT angiogram (CTA), using a dye injection, then shows the arteries and the aneurysm.
MRI and MRA are mainly used to look for aneurysms that have not burst: for screening, for checking symptoms, and for follow-up scans.
Sometimes doctors need a catheter angiogram, in which a thin tube is passed through an artery to the brain and dye is injected. It gives the most detailed view and is used to plan treatment.
Screening people with no symptoms is not recommended for everyone, because most aneurysms never burst and finding one can lead to worry and further tests.
But experts do consider screening for people at higher risk (Rinkel and Ruigrok, International Journal of Stroke 2022):
Two or more close relatives (parents, brothers, sisters or children) who have had a brain aneurysm or a bleed from one.
People with polycystic kidney disease (ADPKD), an inherited kidney condition.
Some experts also consider screening for people with one affected close relative, and for adults over 35 who smoke or have smoked and have high blood pressure.
If any of these apply to you, talk to a neurologist or neurosurgeon about whether an MRA is right for you.
Ask about your symptoms and history: headaches, eye problems, blood pressure, smoking and family history.
Choose a scan: CT or CTA in an emergency; MRI with MRA for unburst aneurysms or screening.
Read the scan: a radiologist reviews the pictures and writes a report.
Assess the aneurysm: if one is found, doctors look at its size, shape and position, and your age and health, to judge the chance of it bursting.
Plan the care: regular monitoring scans, treatment, or referral to a neurosurgeon or neurointerventional specialist.
Treatment depends on the aneurysm's size, shape and position, the chance of it bursting, and the person's age and general health. There are three main options.
1. Regular scans and checkups (monitoring). Many small aneurysms have a low chance of bursting, and treatment carries its own risks. So doctors often recommend watching the aneurysm with regular MRA scans, together with:
Keeping blood pressure under control.
Stopping smoking.
Attending every follow-up visit and scan. Do not skip them; a change in size or shape can change the advice.
2. Treatment through a blood vessel (endovascular treatment). A thin tube is passed into an artery, usually at the groin or wrist, and guided up to the aneurysm. Tiny platinum coils, or other small devices such as a stent or flow diverter, are used to stop blood flowing into it. This is often called coiling. It avoids opening the skull, but it is still a procedure with risks.
3. Brain surgery (clipping). A neurosurgeon opens the skull and places a tiny metal clip across the neck of the aneurysm, sealing it off from the artery.
When there is time, the doctor will explain the options, benefits and risks of each before deciding.
Yes. Many aneurysms that have not burst are safely monitored without any procedure, with regular scans and good blood pressure control. Coiling is also an option without open surgery. A specialist must decide which approach is safe for you.
A burst aneurysm is different: it needs emergency hospital care and usually a procedure to seal the aneurysm and stop further bleeding.
There is no proven home remedy that closes a brain aneurysm. Do not start or stop any medicine, including blood thinners, without talking to your doctor.
An aneurysm that has not burst may never cause a serious problem. The risk depends on its size, position and the person's health.
A burst aneurysm is far more serious. These are the published figures (Brain Aneurysm Foundation):
These are averages, and the brain aneurysm survival rate for one person depends on how much bleeding there is, how quickly treatment starts, their age and their health. The figures are the strongest reason to treat a sudden severe headache as an emergency.
Recovery after a bleed can take weeks to months. It may include hospital care, physiotherapy, speech therapy and help with memory or daily tasks. Many people do return to independent life. Ask the medical team about the outlook in each case.
Not every brain aneurysm can be prevented, but these steps lower the risk of one forming, growing or bursting:
Keep your blood pressure under control. High blood pressure strains weak artery walls. Have it checked regularly.
Stop smoking, and avoid other people's smoke. Smoking is one of the strongest risk factors for aneurysms and for rupture.
Avoid cocaine and other stimulant drugs, which cause sudden spikes in blood pressure.
Limit alcohol, especially heavy drinking.
Tell your doctor about your family history. If two or more close relatives have had an aneurysm, ask whether screening is right for you.
Go for follow-up scans if you already have an aneurysm.
Treat a sudden, severe headache as an emergency. Call 108 or 112.
These steps lower some risks, but they cannot promise that an aneurysm will never form or burst.
Vital Insights is a performance and longevity lab in Chennai offering MRI scans and other health tests. If your doctor advises a brain MRI or MRA, we can do the scan and send the radiologist's report to your doctor.
We offer MR angiography (MRA), scanner field strength with detailed report. We offer aneurysm screening for people with a strong family history.
Talk to a qualified doctor first: they can decide whether you need an MRI, MRA, CT scan or another test. Learn more at vitalinsights.in.
A brain aneurysm is a weak, bulging spot in a brain artery. About 3 in 100 adults have one, most never cause symptoms, and most never burst.
MRI with MRA can find aneurysms without radiation or dye and is used to monitor them over time. Treatment ranges from regular scans to coiling or clipping. If you have a strong family history, ask your doctor whether screening is right for you.
Remember: a sudden, severe headache, the worst of your life, can mean a burst aneurysm. Call 108 or 112 straight away.
Vlak MHM, Algra A, Brandenburg R, Rinkel GJE. Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systematic review and meta-analysis. Lancet Neurol. 2011;10(7):626–636.
Sailer AMH, Wagemans BAJM, Nelemans PJ, de Graaf R, van Zwam WH. Diagnosing intracranial aneurysms with MR angiography: systematic review and meta-analysis. Stroke. 2014;45(1):119–126.
Rinkel GJE, Ruigrok YM. Preventive screening for intracranial aneurysms. Int J Stroke. 2022;17(1):30–36.
Brain Aneurysm Foundation. Statistics and facts. 2024.
Thunderclap headache. Life in the Fast Lane.
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