What it is
A cerebral aneurysm is a weakened, outpouching area in the wall of an artery supplying the brain. They are more common than most people realize — roughly 2–5% of adults have one. The vast majority never rupture.
When an aneurysm does rupture, the result is a subarachnoid hemorrhage: blood spilling into the space around the brain. This is a medical emergency with significant risk of death and permanent neurological injury. Severe sudden-onset headache — "the worst headache of my life" — is the hallmark and warrants immediate evaluation.
Risk of rupture and treatment decisions
Not all aneurysms need treatment. The annual rupture risk for most small, incidentally discovered aneurysms is low — well under 1% per year. Treatment carries its own risks. The decision to treat versus observe is based on a careful analysis of:
- Size and shape — larger aneurysms and those with irregular or multilobulated contours carry higher rupture risk
- Location — some locations are higher risk than others
- Patient age and health — younger patients have more cumulative lifetime rupture risk; treatment risk must be weighed against this
- Prior rupture — a ruptured aneurysm has a high early re-rupture risk and is treated urgently
Treatment options
Two well-established treatments are available:
- Surgical clipping — a craniotomy is performed and a titanium clip is placed across the aneurysm neck, permanently excluding it from circulation. Durable. Appropriate when anatomy favors a surgical approach.
- Endovascular coiling or flow diversion — a catheter-based approach through the femoral artery fills the aneurysm with coils or uses a mesh device to redirect blood flow away from the aneurysm. Less invasive. Performed by an interventional neuroradiologist.
The choice between clipping and coiling depends on aneurysm anatomy, location, and patient factors, and is best made through a multidisciplinary discussion.