Brain aneurysm symptoms: what a rupture feels like

Most brain aneurysms cause no symptoms at all until they rupture. When one ruptures, the classic symptom is a sudden, severe headache that people often describe as the worst headache of their life, sometimes with a stiff neck, vomiting, confusion or loss of consciousness. A suspected rupture is a medical emergency: call 911 or your local emergency number right away.

When should you call emergency services?

Call 911 or your local emergency number immediately if you or someone near you has:

• a sudden, severe headache that reaches full strength within seconds to a minute (often called a thunderclap headache)
• a headache that feels like the worst of your life, even if it starts to ease
• a sudden headache with a stiff neck, nausea or vomiting, sensitivity to light, confusion or fainting
• a seizure, especially with a severe headache
• sudden double vision, a drooping eyelid or a widened pupil in one eye
• signs of stroke, such as face drooping, arm or leg weakness, or trouble speaking

Do not drive yourself to the hospital, and do not wait to see whether the headache passes. Fast treatment can save a life.

What are the symptoms of a brain aneurysm?

An unruptured brain aneurysm usually causes no symptoms and is often found by chance on a scan done for another reason. A brain aneurysm is a weak spot in an artery wall that bulges outward like a small balloon.

Larger aneurysms can press on nearby nerves or brain tissue and cause:

• pain above or behind one eye
• double vision or blurred vision
• a drooping eyelid or a dilated pupil
• numbness or weakness on one side of the face

These symptoms deserve prompt medical attention, because they can mean an aneurysm is growing.

What does a brain aneurysm feel like when it ruptures?

A ruptured aneurysm usually feels like a sudden, explosive headache unlike anything the person has felt before. Many people describe it as being hit on the head. It may come with nausea, vomiting, a stiff neck, light sensitivity, confusion, a seizure or collapse.

Some people have a smaller warning headache in the days or weeks before a major rupture, sometimes called a sentinel headache. It may come from a small leak of blood. Any sudden, unusually severe headache should be checked urgently.

What happens when a brain aneurysm ruptures?

When an aneurysm ruptures, blood spills into the space around the brain, a type of bleeding called subarachnoid hemorrhage. The blood raises pressure inside the skull and irritates the brain and its blood vessels.

The danger does not end with the first bleed. In the days and weeks that follow, doctors watch for:

• Rebleeding, which is most likely soon after the first bleed and is a main reason the aneurysm is treated quickly.
• Vasospasm, a narrowing of brain arteries that typically develops a few days after the bleed and can cause a stroke.
• Hydrocephalus, a buildup of fluid in the brain that may need a drain.
• Seizures and changes in the body's salt balance.

Treatment usually means sealing the aneurysm with surgical clipping or endovascular coiling, followed by close monitoring in intensive care.

What is the survival rate of a ruptured brain aneurysm?

Roughly half of ruptured brain aneurysms are fatal, and some people die before reaching the hospital. Survival has improved with faster diagnosis and modern treatment, and outcomes depend heavily on how severe the bleed is and how quickly care begins.

Among survivors, recovery varies widely. Some return to their previous lives, while many live with lasting effects such as fatigue, memory problems, headaches, anxiety or physical disability. Doctors often describe long-term function with the modified Rankin Scale, which runs from no symptoms to severe disability.

What causes brain aneurysms?

Brain aneurysms form when an artery wall weakens and bulges, usually over many years rather than from birth. Factors linked to a higher risk include:

• smoking
• high blood pressure
• a family history of brain aneurysms, especially in two or more close relatives
• inherited conditions such as polycystic kidney disease and some connective tissue disorders
• heavy alcohol use and stimulant drugs such as cocaine
• older age and female sex

How common are brain aneurysms?

Brain aneurysms are fairly common: large studies estimate that around 3 percent of adults have one. Most are small and never rupture. Rupture is much rarer than the aneurysms themselves, and the yearly risk for a typical small aneurysm is generally considered low.

How are brain aneurysms detected?

Brain aneurysms are detected with imaging of the blood vessels. The main tests are:

• CT angiography, a CT scan with contrast dye.
• MR angiography, an MRI scan of the blood vessels, often done without dye.
• Catheter angiography, the most detailed test, in which dye is injected through a thin tube in an artery.

When a rupture is suspected, a CT scan of the head is usually the first test. If it is normal but suspicion remains, a lumbar puncture can look for blood in the spinal fluid. Screening of people without symptoms is usually reserved for those at higher risk, such as people with a strong family history.

Brain aneurysm vs stroke: what is the difference?

A brain aneurysm is a bulge in an artery, while a stroke is brain injury from interrupted blood flow or bleeding. A ruptured aneurysm causes a type of hemorrhagic (bleeding) stroke.

The more common ischemic stroke, caused by a blocked artery, usually starts with sudden weakness, numbness, face drooping or trouble speaking, often without a severe headache. A ruptured aneurysm more often starts with an explosive headache. Both are emergencies.

What should you avoid if you have a brain aneurysm?

If you have an unruptured aneurysm, the most important steps are to stop smoking and keep your blood pressure well controlled. Avoid cocaine, amphetamines and other stimulants, and limit alcohol. Ask your doctor before starting or stopping blood thinners, and ask whether any limits on heavy lifting or intense exertion apply to you, since advice differs between specialists.

Not every aneurysm needs treatment. Small aneurysms are often monitored with periodic scans, while others are treated with clipping or coiling. Coiled aneurysms are followed over time because some refill, a process called recanalization. Uncommon giant intracranial aneurysms, 25 mm or larger, can require complex surgery, sometimes including a bypass to reroute blood flow. Researchers are building models that compare treatment strategies for these large aneurysms, such as this giant aneurysm strategy tool.

Frequently asked questions

Can you feel a brain aneurysm before it ruptures?

Usually not. Most unruptured aneurysms cause no sensation at all. Larger ones can cause eye pain, vision changes or a drooping eyelid by pressing on nerves.

Can stress or exertion cause an aneurysm to rupture?

Sudden spikes in blood pressure, such as during intense straining or exertion, have been reported as possible triggers for rupture. Many ruptures, however, happen during ordinary activity or rest. Long-term blood pressure control matters more than avoiding everyday stress.

Can a brain aneurysm go away on its own?

Brain aneurysms generally do not disappear on their own. Many small aneurysms stay stable for years, which is why monitoring is often a reasonable option.

Do all brain aneurysms need treatment?

No. The decision depends on the aneurysm's size, shape and location, your age and health, and risk factors such as smoking or a prior bleed. A specialist team weighs the risk of rupture against the risk of treatment.