What is a brain aneurysm?
A brain or intracranial aneurysm is an abnormal focal dilation of an artery in the brain that results from the weakening of the inner muscular layer (the intima) of the wall of a blood vessel. The vessel develops a “blister-like” dilation that can thin and rupture without warning. The resulting bleeding into the space around the brain is called a subarachnoid hemorrhage (SAH). This type of bleeding can lead to stroke, coma, and/or death.
Aneurysms are typically established at the base of the brain, just inside the brain, in an area called the subarachnoid space. 90 percent of SAH are attributed to ruptured brain aneurysms, and the two terms are often used synonymously.
Aneurysms range in size from small (about 1/8 inch) to almost an inch. Aneurysms larger than one inch are called giant aneurysms, they are particularly high risk and difficult to treat. The exact mechanisms by which brain aneurysms develop, grow, and fracture is unknown.
Symptoms of a brain aneurysm
Sudden, severe pain is the key sign of a ruptured aneurysm. This headache is regularly defined as the “worst headache” ever experienced.
Corporate signs and symptoms of a ruptured aneurysm include:
- Sudden and extremely severe headache
- Nausea and vomiting
- Stiff neck
- Blurred or double vision
- Sensitivity to light
- A droopy eyelid
- Loss of consciousness
In some cases, an aneurysm can lose a small amount of blood. This leak (sentinel bleeding) can cause only:
- Sudden and extremely severe headache
- A more severe rupture often follows a leak
An unruptured brain aneurysm may not cause symptoms, especially if it is small. However, a larger unruptured aneurysm can press on the tissues and nerves of the brain, possibly causing:
- Pain above and behind one eye
- Dilated pupil
- Change in vision or double vision
- Numbness on one side of the face
Causes of a brain aneurysm
Any condition that causes the walls of the arteries to weaken can lead to one. The most common culprits are atherosclerosis and high blood pressure. Deep wounds and infections can also lead to an aneurysm. Or you can be born with a weakness in one of your artery walls.
Risk factors for brain aneurysm
Several factors can contribute to the weakness of an artery wall and increase the risk of a brain aneurysm or aneurysm rupture. Brain aneurysms are more common in adults than children and more common in women than men.
Some of these risk factors change over time others are present-day at birth.
Risk factors that develop over time. These include:
- Advanced age
- Smoking cigarettes
- High blood pressure (hypertension)
- Drug abuse, particularly cocaine use
- Excessive alcohol consumption
Some types of aneurysms can occur after a head injury (dissecting aneurysm) or certain blood infections (fungal aneurysm).
Risk factors present at birth
Selected conditions dating from birth may be associated with an elevated risk of developing a brain aneurysm. These include:
- Hereditary connective tissue disorders, such as Ehlers-Danlos syndrome, which weaken blood vessels.
- Polycystic kidney disease, an inherited disorder that produces fluid-filled sacs in the kidneys and usually increases blood pressure.
- Abnormally narrow aorta (coarctation of the aorta), the large blood vessel that carries oxygen-rich blood from the heart to the body.
- Cerebral arteriovenous malformation (cerebral AVM), an abnormal connection between arteries and veins in the brain that interrupts the normal flow of blood between them.
- Family past of brain aneurysm, particularly a first-degree relative, such as a parent, brother, sister, or child.
Diagnosis of a brain aneurysm
If you experience a sudden, severe headache or other symptoms possibly related to a ruptured aneurysm, you will undergo a test or series of tests to determine if you have bled into the space between the brain and surrounding tissues (subarachnoid hemorrhage). or possibly another type of stroke.
If bleeding has occurred, your emergency care team will determine if the cause is a ruptured aneurysm.
If you show symptoms of an unruptured brain aneurysm, such as pain behind the eye, vision changes, or double vision, you will also have some tests to identify the causative aneurysm.
Diagnostic tests include:
Computed tomography (CT): A CT scan, an expert X-ray exam, is usually the first test used to determine if you have bleeding in the brain. The test produces images that are two-dimensional “parts” of the brain.
With this test, you may also undergo an injection of a dye that makes it easier to see blood flow in the brain and can indicate the presence of an aneurysm. This difference in the test is called CT angiography.
Cerebrospinal fluid test: If you’ve had a subarachnoid hemorrhage, there are most likely red blood cells in the fluid that surrounds your brain and spine (cerebrospinal fluid). Your doctor will order a cerebrospinal fluid test if you have symptoms of a ruptured aneurysm, but a CT scan has shown no evidence of bleeding.
The procedure to remove cerebrospinal fluid from the back with a needle is called a lumbar puncture (lumbar puncture).
Magnetic resonance imaging (MRI): An MRI uses a magnetic field and radio waves to create detailed images of the brain, either in 2-D slices or 3-D images.
A type of MRI that evaluates the arteries in detail (magnetic resonance angiography) can detect the presence of an aneurysm.
Cerebral angiogram: During this procedure, also called a cerebral arteriogram, your doctor inserts a thin, flexible tube (catheter) into a large artery, usually in the groin, and passes it through the heart into the arteries in the brain. A special dye that is injected into the catheter travels to arteries throughout the brain.
A series of X-ray images can reveal details about the conditions of your arteries and detect an aneurysm. This test is more invasive than others and is generally used when other diagnostic tests do not provide enough information.
Treatment for brain aneurysm
There are two common treatment choices for a ruptured brain aneurysm.
- Surgical trimming is a procedure to close an aneurysm. The neurosurgeon gets rid of a section of your skull to access the aneurysm and finds the blood vessel that foods the aneurysm. Then, he places a small metal clip on the neck of the aneurysm to stop the flow of blood.
- Endovascular coiling is a less invasive procedure than the surgical clip. The surgeon inserts a hollow plastic tube (catheter) into an artery, usually in the groin, and passes it through your body to the aneurysm.
Next, he uses a guide wire to push a soft platinum wire to complete the catheter and into the aneurysm. The wire coils inside the aneurysm interrupt blood flow and essentially seals the aneurysm from the artery.
Both of these procedures present potential risks, particularly bleeding in the brain or loss of blood flow to the brain. Endovascular coiling is less invasive and may be safer initially, but may have a slightly higher risk of needing a repeat procedure in the future due to the reopening of the aneurysm.
Newer treatments available for brain aneurysm include flow diverters, tubular stent-shaped implants that work by diverting blood flow away from the aneurysm sac. Bypassing stops the movement of blood within the aneurysm and thus stimulates the body to heal the site, which encourages reconstruction of the mother artery. Flow diverters can be above all useful in larger aneurysms that cannot be safely treated with other options.
Your neurosurgeon or interventional neuroradiologist, in collaboration with your neurologist, will make a commendation based on the size, location, and general appearance of the brain aneurysm, your ability to undergo a procedure, and other factors.
Other treatments (ruptured aneurysms)
Other treatments for ruptured brain aneurysms aim to relieve symptoms and control complications.
- Pain relievers, such as acetaminophen (Tylenol, others), can be used to treat headaches.
- Calcium channel blockers prevent calcium from entering the cells of the blood vessel walls. These medications can decrease the erratic narrowing of the blood vessels (vasospasm) that can be a complication of a ruptured aneurysm.
One of these drugs, nimodipine has been shown to decrease the risk of late brain damage caused by insufficient blood flow after subarachnoid hemorrhage from a ruptured aneurysm.
- Interventions to prevent a stroke due to insufficient blood flow include intravenous injections of a drug called a vasopressor, which raises blood pressure to overawed the resistance of narrowed blood vessels. An alternative intervention to prevent a stroke is angioplasty. In this procedure, a surgeon uses a catheter to inflate a small balloon that expands a narrow blood vessel in the brain. A medicine known as a vasodilator can also be used to expand the blood vessels in the affected area.
- Anti-seizure medications can be used to treat seizures related to a broken aneurysm. These medicines include levetiracetam phenytoin (Dilantin, Phenytek, others), valproic acid (Depakene), and others. Its use has been debated by various experts and is generally subject to the discretion of the caregiver, depending on the medical needs of each patient.
- Ventricular or lumbar drainage catheters and bypass surgery can lower pressure on the brain from excess cerebrospinal fluid (hydrocephalus) associated with a ruptured aneurysm. A catheter may be placed into the fluid-filled spaces within the brain (ventricles) or around your brain and spinal cord to drain excess fluid into an external bag. Sometimes it may be necessary to insert a shunt system, which consists of a flexible silicone rubber tube (shunt) and a valve, which creates a drainage channel that begins in your brain and ends in your abdominal cavity.
- Rehabilitation therapy: Damage to the brain from a subarachnoid hemorrhage can result in the need for physical, speech, and occupational therapy to relearn skills.
When a brain aneurysm ruptures, the bleeding usually lasts for only a few seconds. Blood can cause direct damage to surrounding cells, and bleeding can damage or destroy other cells. It also increases the pressure inside the skull.
If the pressure becomes too high, the supply of blood and oxygen to the brain can be cut off to the point of loss of consciousness or even death.
Complications that can develop after an aneurysm ruptures include:
- New bleeding. An aneurysm that has ruptured or leaks is at risk of bleeding again. Re bleeding can cause more damage to brain cells.
- Vasospasm. After a brain aneurysm ruptures, the blood vessels in the brain can narrow erratically (vasospasm). This situation can limit blood flow to brain cells (ischemic stroke) and cause added cell damage and loss.
- Hydrocephalus. When a ruptured aneurysm causes bleeding into the space between the brain and surrounding tissue (subarachnoid hemorrhage), more often, the blood can block the circulation of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid). This condition can result in excess cerebrospinal fluid that increases pressure on the brain and can damage tissues (hydrocephalus).
- Hyponatremia. Subarachnoid hemorrhage from a ruptured brain aneurysm can upset the sodium balance in the blood. This can occur from damage to the hypothalamus, an area near the base of the brain.
A decrease in sodium levels in the blood (hyponatremias) can lead to inflammation of brain cells and permanent damage.
If you have an enraptured brain aneurysm, you can reduce your risk of rupturing by making these lifestyle changes:
- Don’t smoke or use recreational drugs. If you smoke or use recreational drugs, talk with your doctor about strategies or an appropriate treatment program to help you quit smoking.
- Eat a healthy diet and exercise. Changes in diet and exercise can help lower blood pressure. Talk to your doctor about the changes that are right for you.
Departments to consult for this condition
- Department of Neurology