Introduction to Blister (Brain) Aneurysm

When people think of brain aneurysms, the common “berry” or saccular aneurysm often comes to mind. However, there’s another, far rarer form known as a blister aneurysm - small, fragile, and highly prone to rupture. Because of their delicate structure and unpredictable behaviour, blister aneurysms require early detection and expert management.

What is a blister aneurysm? A blister aneurysm (or blood blister-like aneurysm or dissecting aneurysm) is a tiny, thin-walled outpouching that forms on a weakened area of a brain artery - most commonly along the internal carotid artery. Instead of forming a well-outlined sac, they appear as a small, fragile blisters or ulcers on a weakened section of the vessel wall. This structural difference makes them extremely fragile. Even when small, blister aneurysms can rupture suddenly, leading to potentially life-threatening bleeding around the brain.

This article is part of our guide to understanding brain aneurysm types. For a full overview of all types and how they differ, visit: Understanding the Types of Brain Aneurysms. You might also be interested understanding brain aneurysms in our article, Brain Aneurysm: What You Should Know.

Why Blister Aneurysms Are Concerning and What Makes Them Unique

According to NIH, blood blister-like aneurysms (BBAs) are a rare type of intracranial aneurysm, typically accounting for less than 2% of all intracranial aneurysms. Some sources report their prevalence as approximately 0.3%–1% of all intracranial aneurysms or 1%–2% of all aneurysmal subarachnoid hemorrhages.

Blister aneurysms are unstable, fast-changing, and at high risk of rupture. When rupture occurs, it often results in a subarachnoid hemorrhage, a serious type of brain bleed that requires immediate medical attention. Their structure lacks the normal muscular and elastic layers found in healthy arteries, leaving them particularly vulnerable to tearing or bleeding. Because of their delicate nature and tiny size, they can be difficult to identify on imaging scans, often requiring advanced diagnostic techniques and expert interpretation. Visit our, Are Small Brain Aneurysms Dangerous?, to learn more.

Possible Causes and Risk Factors

The exact cause of blister aneurysm formation is still not fully understood. However, several factors may contribute to their development, including:

• Chronic high blood pressure (hypertension)
• Atherosclerosis (hardening or thickening of the arteries)
• Inflammation or injury to the arterial wall
• Connective tissue disorders that weaken blood vessels
• Stress or trauma to the vessel (head or neck)
• In some cases, no clear cause can be identified.

These aneurysms can form spontaneously, making awareness and early screening even more important for individuals with vascular risk factors.

Recognising the Symptoms of a Ruptured Blister Aneurysm

The symptoms of a ruptured blister aneurysm are often sudden and severe. Common warning signs include:

• An abrupt, intense headache (often described as “the worst headache of your life”)
• Neck pain or stiffness
• Nausea and vomiting
• Loss of consciousness or confusion
• Blurred or double vision
• Weakness, numbness, or speech difficulties

Anyone experiencing these symptoms should seek emergency medical care immediately. Rapid intervention is critical to reduce the risk of permanent damage or death. Visit, Brain Aneurysm Symptoms and Rupture: What to Watch For, to learn more.

How Blister Aneurysms Are Diagnosed

Because blister aneurysms are small, irregular, and fragile, they can be challenging to detect using standard brain scans. Accurate diagnosis often requires a combination of advanced neuroimaging techniques performed by an experienced neurointerventional specialist.

CT Scan and CT Angiography (CTA)

A CT scan is usually the first imaging test done when a brain bleed is suspected. It helps identify signs of subarachnoid hemorrhage - bleeding around the brain that can occur when an aneurysm ruptures. To get a clearer view of the blood vessels, a CT angiography (CTA) may follow. This test uses contrast dye to produce detailed 3D images of the brain’s arteries, allowing doctors to detect aneurysms or abnormal vessel structures.

Cerebral Angiogram

Cerebral angiogram is considered the gold standard for diagnosing small or complex aneurysms, including blister aneurysms. During this procedure, a thin catheter is inserted through an artery in the groin or wrist and guided to the brain’s blood vessels. A contrast dye is then injected, and X-ray images are taken to precisely map the arteries.

Because blister aneurysms are often tiny and irregularly shaped, repeat or high-resolution imaging may be necessary to confirm the diagnosis. In Singapore, these advanced imaging tests are typically performed in specialized neurointervention and vascular centers to ensure accurate detection and effective treatment planning.

Treatment and Management Options in Singapore

Because of their instability, blister aneurysms often require individualized treatment plans. Options may include:

• Endovascular treatments, such as flow-diverting stents, to redirect blood flow and promote vessel healing.
• Surgical approaches, including microsurgical clipping or wrapping in carefully selected cases.
• The expertise of a brain aneurysm specialist combined with multi-disciplinary approach to ensure the safest possible outcome.

Early recognition and precise imaging play a crucial role in achieving good results.

Protecting Your Brain Health 

Blister aneurysms are rare but potentially life-threatening. They may be rare, but their delicate nature means every moment counts. Recognizing the signs, seeking early evaluation, and consulting a specialist are key to preventing serious complications. Their fragile structure means they can rupture without warning. If you experience sudden, severe headaches or have risk factors such as hypertension, atherosclerosis, or a family history of aneurysms, don’t delay, consult a brain aneurysm specialist for proper evaluation.  If you’re unsure where to begin, you may explore our step-by-step guide to understanding your brain aneurysm journey. 

At the Supreme Vascular and Interventional Clinic, our specialized brain aneurysm clinic in Singapore, Dr. Manish Taneja offers advanced diagnostic imaging and minimally invasive treatment for all types of brain aneurysms, including rare and complex cases like blister aneurysms. Your brain health deserves the highest level of care - timely diagnosis and expert management can make all the difference. We invite you to schedule a consultation today. 

Brain Aneurysm Resources

Explore our brain aneurysm resources. Understanding a brain aneurysm often involves learning across several areas.

Brain Aneurysm Coiling and Stent

Types of Brain Aneurysm Headaches

Put Brain Aneurysm on Your Health Radar

Did you experience the worst headache of your life? Thoughts could be racing through your mind. A brain aneurysm is a weak spot in a blood vessel in the brain that can change over time. The key concern is when an aneurysm ruptures, which can disrupt blood flow, affect brain tissue, and lead to serious brain damage. Controllable conditions like high blood pressure can increase this risk and treatment options can depend on the condition. Surgical clipping is one option that prevents blood from entering the weakened area. In many cases, minimally invasive treatments can also be used to restore normal blood flow and reduce risk. We have created structured guides to help you explore each stage in more detail:

A simple (computed tomography) CT scan could be just what the doctor ordered and the first step in early detection and prevention of a brain aneurysm. Come in for an easy consultation with our brain aneurysm specialist in Singapore to be on your health radar. 

Other Health Conditions

Venous Diseases (Varicose Veins)

The Supreme Vascular and Interventional Clinic is your “go-to” facility for various conditions and treatments. To arrange an appointment with Dr. Manish Taneja, our brain aneurysm specialist, contact us. You can also call us at (+65) 6904 8084 for a consultation.