Reviewed personally by Dr. Sunkara · Written for Brain Aneurysm & AVM · Updated September 2026
Quick Answer
A brain aneurysm is a weak, bulging spot on a blood vessel wall inside the brain, shaped like a small balloon filled under pressure. Most stay silent for years and are found only on a scan done for something else. A related but separate condition, an AVM, is a tangle of blood vessels rather than a single bulge.
Most people assume an aneurysm forms overnight. It doesn't. Constant blood flow presses against a naturally thin point in an artery wall, and over years that spot stretches outward, the way a worn tyre bulges before it fails. Most brain aneurysms never rupture, and honestly, that surprises most people when they first hear it. The ones that do tend to sit where arteries branch at the base of the brain, where blood pushes hardest and turns most sharply.
Brain aneurysms become more common with age and show up more often in women than men. An AVM, by contrast, is usually present from birth. Not every brain aneurysm needs surgery. Many are simply watched, with regular scans tracking whether they change over time.
Your scan report will usually name one of the first three. The last card, an AVM, is a different blood vessel problem, but it's often confused with an aneurysm, so it helps to tell them apart.
A sudden, violent headache unlike anything you've felt before, often called the worst headache of your life, is the single most important warning sign. Don't wait to see if it passes. Call for emergency help immediately and get to a hospital with neurosurgery capability.
Call For Emergency Help If You Have:
01
If you come in with a sudden severe headache or an aneurysm is suspected for another reason, a CT scan is usually the first test, since it's fast and widely available in an emergency.
02
A detailed scan that maps the brain's blood vessels using a contrast dye, showing the aneurysm's exact size, shape, and location well enough to plan treatment around it, without an invasive procedure.
03
The gold standard test, a catheter threaded through a blood vessel captures the most detailed picture of an aneurysm, usually reserved for cases where surgery or coiling is already being planned.
Treatment depends on the aneurysm's size, location, and whether it has ruptured, not on a single fixed rule. Many small, unruptured aneurysms are simply watched rather than treated right away.
Regular MRI or CT angiography on a set schedule to track a small, unruptured aneurysm's size and shape over time, stepping in only if it changes.
A catheter is guided up to the aneurysm, then filled with soft platinum coils that encourage clotting and seal it off from blood flow.
See Neurovascular Surgery →A small metal clip is placed across the aneurysm's neck during open surgery, permanently closing it off while leaving the healthy artery intact.
See Neurovascular Surgery →Targeted radiation delivered over one or a few sessions gradually closes off a small AVM's abnormal vessels, an option when open removal carries too much risk.
See Stereotactic Radiosurgery →Often, yes. Once coiling or clipping seals an aneurysm off, it rarely causes trouble again, though scans keep an eye on it over the years. A small one that's only being watched isn't cured, but many never grow or bleed. Many patients arrive expecting a ticking time bomb and leave with a calmer plan.
What can you actually control once you've been diagnosed with a brain aneurysm?
QUIT SMOKING
The single biggest change you can make. Smoking accelerates aneurysm growth and raises rupture risk more than almost any other factor you control.
CONTROL BLOOD PRESSURE
Keeping blood pressure in a healthy range, with medication if needed, reduces the ongoing stress on artery walls, both treated and untreated.
KEEP SCHEDULED SCANS
For a watched aneurysm, missing a follow-up scan means losing track of whether it's changing, which is the one thing that decides treatment.
TELL YOUR FAMILY
A first-degree relative's history matters for screening decisions, so it's worth letting close family know if you've been diagnosed with an aneurysm.
Is my aneurysm's size and shape considered high risk for rupture?
Would you recommend watching this aneurysm, or treating it now?
If treatment is needed, would coiling or clipping suit my case better?
How often will I need follow-up scans if we choose to watch it?
Should any of my close family members be screened as well?
Bring your scan images to a consultation, and Dr. Sunkara will walk through what they mean for your specific case.
A brain aneurysm is a weak, bulging spot on a blood vessel wall in the brain. Most stay silent for years and are found by accident, though a ruptured one is an emergency.
Bring your scan report for a second opinion, or book a consultation to talk through whether watching, coiling, or clipping is right for you.
Written & reviewed by Dr. Raveesh Sunkara, Senior Consultant Neurosurgeon & Spine Surgeon · Last updated September 2026 · Next review due March 2027