A brain aneurysm — also known as a cerebral or intracranial aneurysm — occurs when a blood vessel in the brain develops a weak, bulging spot that looks like a “berry” hanging from a stem. While many aneurysms remain harmless and never cause symptoms, a rupture can lead to a life-threatening hemorrhagic stroke within minutes.

Understanding the signs, risks, and complications can save lives. Here’s what every person should know.

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What Is a Brain Aneurysm?

A brain aneurysm forms when constant blood pressure pushes against a weakened area of an artery wall, causing it to balloon outward. If the aneurysm leaks or bursts, blood spills into the space surrounding the brain — a dangerous condition known as a subarachnoid hemorrhage.

Most aneurysms are small and do not rupture. Many are discovered accidentally during scans done for unrelated health issues. But a ruptured aneurysm is a medical emergency requiring immediate treatment.

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Types of Brain Aneurysms

✅ Saccular (Berry) Aneurysm

The most common type. A round, blood-filled sac bulges from an artery, usually near the base of the brain.

✅ Fusiform Aneurysm

The artery expands outward on all sides, creating a spindle-shaped dilation.

✅ Mycotic Aneurysm

Caused by an infection that weakens the arterial wall.

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Symptoms of a Ruptured Aneurysm

A ruptured brain aneurysm typically causes a sudden, severe headache — often described as:

“The worst headache of my life.”

Other symptoms may include:

• Nausea and vomiting

• Stiff neck

• Blurred or double vision

• Sensitivity to light

• Seizures

• Loss of consciousness

• Confusion or disorientation

This is a medical emergency. Call 911 immediately.

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Symptoms of a “Leaking” Aneurysm

Sometimes a small amount of blood escapes before a major rupture. Warning signs may appear days or even weeks beforehand.

Common symptom:

• A sudden, intense headache that persists for days.

This should be treated as a red flag.

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Symptoms of an Unruptured Aneurysm

Many unruptured aneurysms cause no symptoms unless they are large enough to press on nerves or brain tissue.

Possible signs include:

• Pain above or behind one eye

• Dilated pupil

• Blurred or double vision

• Numbness on one side of the face

• Seizures

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When to Seek Medical Care

Get emergency help immediately if:

• You or someone nearby experiences a sudden, severe headache

• Someone loses consciousness

• A seizure occurs

Time is critical. Fast treatment can prevent fatal complications.

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What Causes Brain Aneurysms?

Aneurysms form when artery walls weaken. They most often occur at branching points of arteries at the base of the brain.

Several factors increase the risk, including:

✅ Lifestyle & Medical Factors

• Smoking

• High blood pressure

• Heavy alcohol use

• Use of stimulant drugs (especially cocaine)

• Certain blood infections

• Head injuries

✅ Inherited or Genetic Conditions

• Ehlers–Danlos syndrome and other connective-tissue disorders

• Polycystic kidney disease

• Brain arteriovenous malformations (AVMs)

• Narrowing of the aorta (coarctation)

• Family history of brain aneurysm — especially two or more first-degree relatives

Aneurysms most commonly occur in adults aged 30–60, and women are affected more frequently than men.

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Risk Factors for Rupture

Some aneurysms are more likely to burst:

• Large size

• Irregular shape or “daughter sac”

• Certain locations in the brain

• Smoking

• Uncontrolled high blood pressure

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Complications After a Rupture

A ruptured aneurysm may stop bleeding quickly, but even a brief hemorrhage can cause serious damage.

Possible complications include:

🔴 Rebleeding

The aneurysm may bleed again, causing further brain injury.

🔴 Vasospasm

Blood vessels constrict after a hemorrhage, cutting off blood flow and leading to ischemic stroke.

🔴 Hydrocephalus

Blood blocks normal cerebrospinal fluid drainage, causing a dangerous buildup of fluid and pressure in the brain.

🔴 Electrolyte Imbalance

Bleeding may lower sodium levels, resulting in brain swelling and permanent damage.

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Prevention: What You Can Do

While not all aneurysms can be prevented, certain habits significantly reduce risk:

✅ Quit smoking
✅ Control blood pressure
✅ Limit alcohol
✅ Avoid drug use, particularly cocaine
✅ Manage chronic medical conditions with your doctor

If you have a strong family history of aneurysms, talk to your healthcare provider about screening.

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Final Thoughts

Brain aneurysms are often silent — until they’re not. Recognizing early warning signs, understanding your risk, and seeking immediate help for severe, sudden headaches can save your life or the life of someone you love.