What Is a Brain Aneurysm? (Plain Language)
An aneurysm is a bulge that forms at a weakened point in the wall of a blood vessel and can balloon outward over time. In the brain's vessels it most often appears as a sac (berry) shape and usually forms where vessels branch. In many people an aneurysm sits for years without any symptoms and is often noticed by chance on a brain MRI or CT taken for another reason. Having an aneurysm does not by itself mean it will 'burst'; most aneurysms stay silent for life. What matters is that how it should be managed is assessed by a physician according to the aneurysm's features.
Risk Factors and Symptoms
The best-known and modifiable risk factors for developing an aneurysm are smoking and uncontrolled high blood pressure; older age and excessive alcohol use also play a part. In some families and certain inherited conditions (e.g. polycystic kidney disease) they may occur more often. The great majority of aneurysms cause no symptoms. A large aneurysm pressing on neighbouring structures may cause symptoms such as a drooping eyelid, double vision or a change in vision. The truly dangerous situation is when an aneurysm ruptures and bleeds around the brain; this is the emergency described below.
Emergency Warning Signs — Call Emergency Services Now
A ruptured aneurysm is a life-threatening emergency, and a rapid response saves lives. The most typical sign is a sudden, extremely severe headache that begins within seconds and that people often describe as 'the worst headache of my life' or 'something burst in my head'. It may be accompanied by neck stiffness, nausea-vomiting, extreme sensitivity to light, double vision, fainting or confusion. In such a situation, call your local emergency number without delay and go to the nearest emergency department. This content is not a diagnostic tool; the sudden severe headache described above always requires emergency assessment.
How Is It Diagnosed? (General Information)
When an aneurysm is suspected, evaluation begins with the history and an examination; the diagnosis is made with imaging. Aneurysms that cause no symptoms are mostly seen by chance on a brain MRI taken for another reason. To examine the vessels in detail, MR angiography (MRA) or CT angiography (CTA) is used; in some cases the most detailed method, catheter (DSA) angiography, may be needed. A physician decides which test is needed and who is suitable for screening. Screening may be considered in people with a family history of more than one aneurysm or brain haemorrhage; this too is determined by a physician's assessment.
An Overview of Treatment Options
Surgery is not always required for a brain aneurysm. For many small, low-risk aneurysms the most appropriate approach is regular imaging follow-up together with control of risk factors (stopping smoking, managing blood pressure). When treatment is needed, there are two main methods: a closed method from within the vessel (reaching the aneurysm through the groin and filling it from the inside) and open surgery (placing a small clip across the neck of the aneurysm). The decision about which aneurysm should simply be watched and which should be treated by which method rests entirely with the physician and is made according to the aneurysm's size and location and the person's general condition. The information here provides a general framework; the decision specific to you is made by the physician who examines you.
Myths and Misconceptions
One of the most common misconceptions is the belief that 'if you have an aneurysm it will definitely burst'; in fact, most aneurysms stay silent for life. Another is the worry that 'every headache is a warning of an aneurysm'; tension headache and migraine are far more common, but the sudden, worst-of-your-life headache described above is different and is an emergency. Generalisations such as 'an aneurysm always needs surgery' or 'the closed method is always better than open surgery' are also untrue; the right option differs from person to person. Accurate information reduces panic; if you have doubts, consult your physician rather than online comments.