Brain Aneurysm – Symptoms and Causes
What is a Brain Aneurysm
A brain aneurysm is a bulge that forms in a blood vessel in the brain. This bulge happens when a weak spot in the vessel wall stretches outward.
Blood flow creates pressure against this weak area, causing it to balloon out over time. Many people have brain aneurysms without knowing it because small ones often cause no symptoms.
When an aneurysm breaks open (ruptures), it causes bleeding in the brain. This is a type of stroke called hemorrhagic stroke. The most common form occurs in the space between the brain and its protective covering, known as a subarachnoid hemorrhage.
While brain aneurysms are fairly common, most don’t cause problems. Doctors often discover them accidentally during tests for other conditions. However, a ruptured aneurysm is a medical emergency that needs immediate treatment.
Types of Brain Aneurysms
Brain aneurysms come in several different forms, each with distinct characteristics:
Berry Aneurysms (Saccular): These are the most common type, shaped like a round berry hanging from a stem. They form a sac-like pouch that extends from the side of a blood vessel, typically at the base of the brain.
Fusiform Aneurysms: Unlike berry aneurysms, these cause the blood vessel to bulge outward on all sides. Instead of forming a distinct pouch, the entire section of the artery expands.
Mycotic Aneurysms: These develop due to infections that weaken the blood vessel walls. When bacteria affect the arteries in the brain, they can damage the vessel structure, leading to a bulge.
Signs and Symptoms
Burst Blood Vessel
When a brain aneurysm ruptures, it typically causes a sudden, severe headache. Many people describe this as the worst headache they have ever felt. This is the main warning sign of a serious problem.
Other symptoms that may occur with a burst aneurysm include:
- Feeling sick or throwing up
- Neck stiffness
- Unclear or double vision
- Discomfort from bright lights
- Seizures
- One eyelid that droops down
- Passing out
- Feeling confused
Small Leak
Sometimes, an aneurysm may leak a small amount of blood before fully rupturing. These leaks often happen days or weeks before a major rupture occurs.
The main symptom of a leaking brain aneurysm is:
- An extremely severe headache that appears suddenly and may last for several days, up to two weeks
This type of headache should never be ignored as it may signal a more serious rupture is imminent.
Non-Burst Bulge
Many brain aneurysms that haven’t ruptured don’t cause any symptoms, especially smaller ones. These are often found accidentally during brain scans done for other reasons.
However, larger aneurysms might press against brain tissue or nerves, causing symptoms such as:
- Pain above and behind one eye
- A pupil that appears larger than normal
- Vision changes or double
- Numbness on one side of the face
When to Get Help
Seek emergency medical care immediately if you experience:
- A sudden, extremely severe headache unlike any you’ve had before
This kind of headache requires urgent attention as it may indicate a life-threatening condition.
If someone nearby has a severe headache, loses consciousness, or has a seizure, call emergency services immediately. Don’t wait to see if symptoms improve.
About 1–2% of people have aneurysms, though only a small number of these will rupture. People with certain risk factors should consider talking to their doctor about screening. These risk factors include:
- Family history of aneurysms
- Polycystic kidney disease
- Connective tissue disorders
- Smoking history
Quick treatment can save lives when an aneurysm ruptures. Modern treatments involve traditional surgery or less invasive methods that use metal coils or stents to seal damaged blood vessels from the inside.
Causes
Brain aneurysms develop when artery walls become thin and weak. These balloon-like bulges typically form at points where blood vessels branch or fork, as these areas have less structural support. The weakened spots can stretch and swell over time.
Aneurysms mostly form in the arteries at the base of the brain, but they can develop in any brain blood vessel. The natural pressure of blood flow against already weakened vessel walls contributes to their formation and potential growth.
Risk Factors
Several factors may weaken artery walls and increase the risk of developing or rupturing a brain aneurysm. Some of these factors develop over time, while others are present from birth.
Age and Gender Factors
- Adults between 30 and 60 years old face a higher risk
- Women are more likely to develop brain aneurysms than men
Lifestyle Factors That Increase Risk
- Cigarette smoking: Contributes to both aneurysm formation and rupture.
- High blood pressure: Weakens artery walls over time.
- Cocaine and other drug use: Raises blood pressure and may cause infections.
- Heavy alcohol consumption: Increases blood pressure.
Medical and Genetic Conditions
| Condition | How It Affects Aneurysm Risk |
|---|---|
| Ehlers-Danlos syndrome | Weakens blood vessels |
| Polycystic kidney disease | Raises blood pressure |
| Coarctation of the aorta | Narrows the main blood vessel from the heart |
| Brain arteriovenous malformation (AVM) | Disrupts normal blood flow |
Family History
Having family members with brain aneurysms significantly increases the risk. This is especially true if two or more first-degree relatives (parent, sibling, or child) have had brain aneurysms.
Some aneurysms may develop after head injuries or certain blood infections.
Not all aneurysms rupture, but certain factors make rupture more likely:
- Size: Larger aneurysms have a higher rupture risk
- Location: Aneurysms in certain areas of the brain are more likely to rupture.
- Smoking: Continues to damage blood vessels and increase rupture risk.
- Untreated high blood pressure: Puts additional stress on weakened artery walls.
Complications
When a brain aneurysm bursts, several serious issues can follow. These complications need quick medical attention to prevent lasting damage.
Re-bleeding
After an aneurysm ruptures, there’s a risk it might bleed again. This second bleeding episode can cause more harm to brain cells than the first rupture.
Doctors monitor patients closely during the first few days after a rupture to watch for signs of re-bleeding.
Blood Vessel Narrowing
Ruptured aneurysms can trigger nearby blood vessels to tighten and narrow, a condition called vasospasm.
This typically happens 3–14 days after the initial bleeding. When blood vessels narrow, they restrict blood flow to parts of the brain. This can lead to an ischemic stroke and additional brain damage.
Fluid Buildup
Brain aneurysm ruptures often release blood into the space surrounding the brain. This blood can block the normal flow of cerebrospinal fluid, leading to a condition called hydrocephalus.
The trapped fluid puts pressure on the brain, causing symptoms like:
- Headache
- Nausea
- Vision problems
- Confusion
- Difficulty walking
Sodium Imbalance
Bleeding in the brain can disrupt sodium levels in the blood, especially if the rupture damages the hypothalamus.
This part of the brain helps control body salt balance. When sodium levels drop too low, brain cells may swell and suffer permanent damage.
Pressure Problems
The bleeding from a ruptured aneurysm increases pressure inside the skull. High pressure can:
- Cut off blood supply to brain tissue
- Cause loss of consciousness
- Lead to respiratory failure
- Be fatal without prompt treatment
Prevention
There are steps you can take to reduce your risk of brain aneurysms, though they cannot always be prevented.
Quitting smoking is one of the most important actions you can take if you currently smoke.
Work closely with your healthcare provider to manage high blood pressure if you have this condition.
Avoid excessive alcohol consumption and steer clear of recreational drugs, especially cocaine.
These substances can increase your risk of developing or rupturing an aneurysm.
