What is a Brain Aneurysm?

A brain aneurysm, also known as an intracranial aneurysm, is a weak area in the wall of a brain artery that gradually bulges outwards, rather like a small balloon. Most aneurysms develop over many years as a result of weakening of the blood vessel wall.

Many brain aneurysms cause no symptoms and are discovered incidentally during brain imaging performed for another reason. Less commonly, an aneurysm may cause symptoms by pressing on nearby nerves or brain structures. The most serious complication occurs when an aneurysm ruptures, causing bleeding around the brain (subarachnoid haemorrhage), which is a medical emergency.

Most aneurysms develop sporadically and are not inherited. Factors associated with aneurysm formation include cigarette smoking, high blood pressure, increasing age, a family history of aneurysms and certain inherited conditions such as polycystic kidney disease.

Although a diagnosis of a brain aneurysm can be unexpected and concerning, it is important to remember that most unruptured aneurysms never rupture or require treatment. The challenge is determining which aneurysms are likely to remain stable and which are most likely to benefit from intervention.

​What Happens if a Brain Aneurysm is Left Untreated? 

One of the first questions after being diagnosed with a brain aneurysm is whether it will eventually rupture.

For most aneurysms, the answer is no.

Many aneurysms remain stable throughout life without causing problems, while others enlarge over time and carry an increasing risk of rupture.

Published studies suggest that the annual risk of rupture for most unruptured aneurysms is relatively low, although the risk varies considerably between patients.

Factors influencing rupture risk include:

• Aneurysm size
• Aneurysm location
• Irregular aneurysm shape
• Previous aneurysm growth
• Cigarette smoking
• High blood pressure
• Family history
• Patient age

No single factor determines rupture risk. Careful assessment of the aneurysm together with the patient’s overall health, life expectancy and personal circumstances is essential before deciding whether treatment is appropriate.

How is a Brain Aneurysm Diagnosed?

Brain aneurysms are usually identified on CT angiography (CTA) or MR angiography (MRA).

For some aneurysms, cerebral angiography (digital subtraction angiography, DSA) provides additional information regarding the aneurysm’s size, shape, neck configuration and relationship to nearby blood vessels. This information can be invaluable when deciding whether observation, microsurgical clipping or endovascular treatment is the most appropriate option.

​Do All Brain Aneurysms Need Treatment?

Not every brain aneurysm requires treatment.

For many patients, careful observation with periodic imaging provides the safest long-term strategy. For others, the lifetime risk of rupture outweighs the risks associated with treatment.

The decision to intervene requires careful consideration of the aneurysm’s characteristics together with the patient’s age, medical history, overall health, life expectancy and personal goals.

Every treatment recommendation should therefore be individualised.

What Are the Treatment Options?

Several treatment options are available, and many patients benefit from assessment by a multidisciplinary cerebrovascular team involving cerebrovascular neurosurgeons and interventional neuroradiologists.

Observation

Many unruptured aneurysms can be managed safely with regular clinical review and imaging surveillance.

Microsurgical Clipping

Microsurgical clipping involves placing a titanium clip across the neck of the aneurysm to permanently exclude it from the circulation while preserving the parent artery.

When complete clipping is achieved, it provides the most durable long-term protection against future rupture and recurrence. Microsurgical clipping remains the preferred treatment for many aneurysms, particularly in younger patients and for aneurysms with anatomy less suited to endovascular treatment.

Endovascular Treatment

Endovascular treatment is performed from inside the blood vessel using catheters passed through the arteries.

Depending on the aneurysm, treatment may involve:

• Coil embolisation
• Stent-assisted coiling
• Flow-diverting stents
• Intrasaccular devices

These minimally invasive techniques have transformed aneurysm treatment and are particularly suitable for selected aneurysms.

Which Treatment is Best?

There is no single treatment that is appropriate for every brain aneurysm.

The most appropriate management depends on the aneurysm’s size, location, neck anatomy, relationship to nearby blood vessels, patient age, overall health and long-term outlook.

Some aneurysms are best managed with microsurgical clipping, others with endovascular treatment, while many are safest managed with careful observation.

The goal is not simply to treat the aneurysm, but to recommend the strategy that offers the greatest long-term benefit while minimising treatment-related risk.

Why Seek an Early Specialist Opinion?

Every newly diagnosed brain aneurysm deserves careful specialist assessment.

Early review helps determine the individual’s risk of rupture, explains the available treatment options and establishes whether observation or treatment is the most appropriate strategy.

Many aneurysms benefit from discussion within a multidisciplinary cerebrovascular team, ensuring every appropriate treatment option has been carefully considered before recommending the most suitable management plan.

Why Choose Professor Lai?

Brain aneurysms are among the most common cerebrovascular conditions encountered in neurosurgery, yet every aneurysm is unique. Successful management depends on accurately assessing the natural history of the aneurysm, balancing the risks of treatment against the lifetime risk of rupture, and selecting the most appropriate management strategy for each individual patient.

Professor Lai has extensive experience in the assessment and management of both ruptured and unruptured brain aneurysms, with particular expertise in microsurgical aneurysm clipping. Many aneurysms can be managed safely with careful observation, while others are better treated with microsurgery or endovascular intervention. Determining the most appropriate approach requires careful assessment of the aneurysm together with each patient’s individual risk factors, overall health and long-term goals.

Working closely with experienced interventional neuroradiologists as part of a multidisciplinary cerebrovascular team, Professor Lai ensures that every appropriate treatment option—including observation, microsurgical clipping and endovascular therapy—is carefully considered before making an individualised recommendation. Patients are referred from across Melbourne, regional Victoria, throughout Australia and overseas for both primary treatment and complex second opinions.

Every recommendation is guided by sound clinical judgement, the best available evidence and a commitment to recommending the right treatment for the right patient.