What Is a Brain Aneurysm?
A brain aneurysm, also called a cerebral or intracranial aneurysm, is an outpouching from an artery wall inside the skull. The most common type is a saccular or berry aneurysm, which looks like a small balloon arising from a vessel branch point.
The danger is rupture. When an aneurysm bursts, blood escapes into the space around the brain, causing subarachnoid hemorrhage. This can lead to coma, stroke, hydrocephalus, vasospasm, seizures or death if not treated urgently.
An unruptured aneurysm is a risk-management problem. A ruptured aneurysm is an emergency. Treatment decisions for unruptured aneurysms should be careful and individualized; treatment for ruptured aneurysms is urgent because the risk of rebleeding is highest early.
Rupture Symptoms: When to Seek Emergency Care
Sudden, explosive, worst headache of life. This is the classic warning sign of aneurysm rupture.
Blood irritates the meninges, causing severe nausea, vomiting, light sensitivity and neck stiffness.
Some patients faint, become confused, have seizures or arrive in coma.
A posterior communicating artery aneurysm can compress the third nerve, causing eye movement problems and a dilated pupil.
A sudden worst headache, especially with vomiting, collapse, seizure, neck stiffness, drowsiness or neurological deficit, requires emergency evaluation immediately. Do not wait for symptoms to settle.
Rupture Risk: What Factors Matter?
Not every aneurysm needs treatment. Some are safer to observe. Others should be treated before rupture. Risk is estimated from multiple factors, not size alone.
| Factor | Lower Concern | Higher Concern |
|---|---|---|
| Size | Very small and stable | Larger, growing, or symptomatic |
| Location | Some anterior circulation sites | Posterior circulation, posterior communicating artery, basilar tip |
| Shape | Smooth, regular dome | Irregular, daughter sac, wide neck, lobulated shape |
| History | No prior rupture or family history | Previous aneurysm rupture, strong family history, multiple aneurysms |
| Patient Factors | Controlled blood pressure, non-smoker | Smoking, high blood pressure, connective tissue disease, polycystic kidney disease |
An aneurysm that grows on follow-up imaging is treated more seriously, even if it is still relatively small. Growth suggests wall instability.
Diagnosis: CT, CTA, MRA and DSA
- 1
Non-Contrast CT Brain - First test in suspected rupture. It detects subarachnoid blood quickly, especially early after headache onset.
- 2
CT Angiography (CTA) - Fast, widely available test that shows aneurysm location, size, neck, calcification and branch anatomy.
- 3
MR Angiography (MRA) - Useful for screening and follow-up of selected unruptured aneurysms without radiation.
- 4
Digital Subtraction Angiography (DSA) - Catheter angiography remains the most detailed test and is often used when treatment is planned or noninvasive imaging is unclear.
- 5
Lumbar Puncture - May be considered if rupture is strongly suspected but CT is negative, depending on timing and clinical judgment.
Observation and Risk Reduction
Small, low-risk, unruptured aneurysms may be followed with periodic CTA or MRA. Observation is active management: blood pressure control, smoking cessation, cholesterol and diabetes management, and attention to family history all matter.
Small, stable, asymptomatic aneurysms in lower-risk locations, especially when treatment risk exceeds rupture risk.
Growth, irregular shape, symptoms, family history, prior rupture from another aneurysm, high-risk location, or patient preference after counseling.
Microsurgical Clipping
Clipping is open microsurgery. Through a craniotomy, the surgeon exposes the aneurysm and places a tiny titanium clip across its neck, excluding it from blood flow while preserving the parent artery and branches.
Often provides long-term durable closure, especially for middle cerebral artery aneurysms, wide-neck aneurysms, branch-incorporating aneurysms and some complex anatomy.
Risks include stroke, bleeding, seizure, infection, swelling, cranial nerve injury, memory or speech problems, CSF leak and anaesthesia complications. Risk varies by aneurysm site and rupture status.
Endovascular Coiling, Stents and Flow Diversion
Endovascular treatment is performed from inside the blood vessels, usually through the wrist or groin. A catheter is navigated into the brain arteries under X-ray guidance.
Soft platinum coils fill the aneurysm sac, encouraging clotting inside it and reducing rupture risk.
Used for wide-neck aneurysms to keep coils inside the sac and preserve the parent artery.
A dense stent redirects blood flow away from the aneurysm, useful for selected wide-neck, fusiform or sidewall aneurysms.
Stents and flow diverters usually require antiplatelet medicines, which affects timing and suitability, especially after rupture.
Ruptured Aneurysm: Subarachnoid Hemorrhage Care
After rupture, the first priority is to secure the aneurysm by clipping or coiling to prevent rebleeding. Care continues in a neuro-ICU because complications can develop over days.
| Problem | Why It Matters | Management |
|---|---|---|
| Rebleeding | Highest early risk and often catastrophic | Urgent clipping or coiling. |
| Hydrocephalus | Blood blocks CSF pathways causing pressure buildup | External ventricular drain or shunt if needed. |
| Vasospasm | Arteries narrow days after bleeding, causing stroke risk | ICU monitoring, nimodipine, blood flow support, endovascular treatment if severe. |
| Seizures and ICU complications | Can worsen brain injury | Medication, monitoring and rehabilitation planning. |
Recovery and Follow-Up
After Unruptured Aneurysm Treatment
Recovery after elective clipping or coiling is usually smoother than after rupture. Follow-up imaging checks whether the aneurysm remains closed and whether other aneurysms exist.
After Rupture
Recovery can take months and may include fatigue, headache, memory problems, mood changes, weakness, speech difficulty or hydrocephalus. Rehabilitation is often essential.
Long-Term Surveillance
Coiled, stented or flow-diverted aneurysms require imaging follow-up. Some clipped aneurysms also need surveillance, especially if complex, residual or multiple aneurysms are present.
Watch: Brain Aneurysm Clipping and Coiling Explained
Use this video section for patient-friendly explanations of aneurysm rupture, clipping, coiling, flow diversion and ICU recovery.
Watch on YouTube →Questions to Ask Your Neurosurgeon
- 1
Is my aneurysm ruptured or unruptured? - This completely changes urgency and treatment strategy.
- 2
What are the size, location, neck width and shape? - These details drive rupture risk and treatment choice.
- 3
Is observation reasonable, and what imaging schedule should I follow? - Ask what would trigger treatment later.
- 4
Which is better for me: clipping, coiling, stent-assisted coiling or flow diversion? - The best option depends on anatomy and team expertise.
- 5
Will I need antiplatelet medicines? - Important for stents and flow diverters, and for planning other procedures.
- 6
If ruptured, what is the plan for hydrocephalus and vasospasm monitoring? - ICU care is as important as securing the aneurysm.
- 7
How many aneurysm cases does your center treat? - Experience matters for both microsurgical and endovascular treatment.
For unruptured aneurysms, a second opinion can be very useful because observation, clipping, coiling and flow diversion each have different risks and durability. For ruptured aneurysms, treatment should not be delayed.
