Brain Aneurysm: What It Is, Warning Signs, Risk Factors, and When Surgery Is Needed
By Apex Hospitals 11th April, 2026 3 min read
Most people have never thought about the blood vessels in their brain, until something goes wrong. A brain aneurysm is one of those conditions that can exist silently for years, and in some cases, it can become a medical emergency with little warning.
This article explains what a brain aneurysm is, what signs to watch out for, who is at higher risk, and when surgery is the right step.
What Is a Brain Aneurysm?
A brain aneurysm (also called an intracranial aneurysm) is a weak spot in the wall of a blood vessel in the brain that balloons outward and fills with blood. Think of it like a small bubble forming on the side of a pipe where the wall has become thin.
Most aneurysms are small and do not cause any symptoms. They are often discovered by accident during a brain scan done for another reason. However, if an aneurysm grows large enough, or if it ruptures (bursts), it can cause a life-threatening condition called a subarachnoid hemorrhage, where blood leaks into the space around the brain.
Brain aneurysms can occur at any age, but they are most common in adults between 30 and 60 years of age, and slightly more common in women than men.
Signs and Symptoms of a Brain Aneurysm
Unruptured Aneurysm — Often No Symptoms
Many brain aneurysms cause no symptoms at all. When they do, it is usually because the aneurysm has grown large enough to press on nearby nerves or brain tissue. Symptoms of an unruptured aneurysm may include:
• Pain above or behind one eye
• A drooping eyelid
• Blurred or double vision
• Numbness or weakness on one side of the face
• Difficulty speaking
These symptoms should not be ignored. If you experience any of them without a clear reason, see a doctor promptly.
Ruptured Aneurysm — A Medical Emergency
A ruptured brain aneurysm is a medical emergency. The most recognizable symptom is described by patients and doctors as the "worst headache of your life", sudden, severe, and unlike anything felt before. Other signs include:
• A sudden, extremely severe headache
• Nausea and vomiting
• Stiff neck
• Sensitivity to light
• Sudden blurred or double vision
• Loss of consciousness or confusion
• Seizures
If you or someone around you experiences these symptoms, especially a sudden, thunderclap-type headache, call for emergency help immediately. Minutes matter.
Who Is at Risk?
Some people are more likely to develop a brain aneurysm than others. Key risk factors include:
Factors You Cannot Change
• Family history — if a close relative has had a brain aneurysm, your risk is higher
• Certain genetic conditions, such as polycystic kidney disease or connective tissue disorders
• Age — risk increases after 40
• Gender — women are at slightly higher risk, particularly after menopause
Factors You Can Manage
• High blood pressure (hypertension) — the most significant modifiable risk factor
• Smoking — weakens blood vessel walls and dramatically increases risk
• Heavy alcohol use
• Drug use, particularly cocaine and amphetamines
• Head injury
Controlling blood pressure and quitting smoking are the two most impactful things a person can do to reduce their risk.
How Is a Brain Aneurysm Diagnosed?
Because most aneurysms cause no symptoms, they are often found incidentally. When a doctor suspects an aneurysm, or when symptoms are present, the following tests are used:
• CT scan (Computed Tomography) — usually the first test done in an emergency to check for bleeding
• CT Angiography (CTA) — uses contrast dye to give a detailed view of blood vessels
• MRI and MR Angiography (MRA) — provides detailed images without radiation, used for monitoring
• Cerebral Angiogram (DSA) — the gold standard for precise diagnosis; a catheter is used to inject dye directly into the blood vessels
• Lumbar puncture — if CT is normal but a rupture is still suspected, a small sample of spinal fluid is tested
When Is Surgery Needed?
Not every brain aneurysm requires surgery. The decision depends on several factors, the size of the aneurysm, its location, whether it has ruptured, and the overall health of the patient.
Surgery Is Usually Needed When:
• The aneurysm has ruptured — this is always an emergency requiring immediate treatment
• The aneurysm is large (typically greater than 7 mm) and at high risk of rupturing
• The aneurysm is growing — confirmed by repeat imaging over time
• The patient has symptoms that suggest pressure on nearby brain structures
• The patient is young and the lifetime risk of rupture is significant
Monitoring Without Surgery ("Watch and Wait")
Smaller, unruptured aneurysms in older patients or those with significant health conditions may be managed with regular monitoring, blood pressure control, and lifestyle changes. Not all aneurysms need to be treated immediately, but all of them need to be watched.
Surgical Options
When treatment is required, the two main approaches are:
• Surgical Clipping — a neurosurgeon places a tiny metal clip at the base of the aneurysm to stop blood flow into it. This is done under general anaesthesia through an opening in the skull.
• Endovascular Coiling (or Flow Diversion) — a minimally invasive procedure where a catheter is guided through the blood vessels. Tiny coils or a mesh stent are placed inside the aneurysm to block blood flow and allow it to clot safely. No incision in the skull is required.
The choice between these depends on the aneurysm's size, shape, and location, and is made by a team of neurologists and neurosurgeons based on what is safest for the individual patient.
Final Word
A brain aneurysm is not always dangerous, but it is always something to take seriously. The earlier it is found and assessed, the more options are available. If you have a family history of aneurysms, persistent headaches, or any of the symptoms described here, speak with a neurologist.
At Apex Hospitals, our neuroscience team includes specialists in cerebrovascular conditions who work with patients to assess risk, monitor aneurysms, and recommend the right course of treatment, whether that is regular observation or surgical intervention.