Brain aneurysm

Brain aneurysm

Definition:

A brain aneurysm (AN-u-rizm) is a bulge or ballooning in a blood vessel in the brain. It often looks like a berry hanging on a stem.

A brain aneurysm can leak or rupture, causing bleeding into the brain (hemorrhagic stroke). Most often a ruptured brain aneurysm occurs in the space between the brain and the thin tissues covering the brain. This type of hemorrhagic stroke is called a subarachnoid hemorrhage. A ruptured aneurysm quickly becomes life-threatening and requires prompt medical treatment.

Most brain aneurysms, however, don't rupture, create health problems or cause symptoms. Such aneurysms are often detected during tests for other conditions. Treatment for an unruptured brain aneurysm may be appropriate in some cases and may prevent a rupture in the future.

Symptoms:

Ruptured aneurysm
A sudden, severe headache is the key symptom of a ruptured aneurysm. This headache is often described as the "worst headache" ever experienced. Common signs and symptoms of a ruptured aneurysm include:

• Sudden, extremely severe headache
• Nausea and vomiting
• Stiff neck
• Blurred or double vision
• Sensitivity to light
• Seizure
• A drooping eyelid
• Loss of consciousness
• Confusion

'Leaking' aneurysm
In some cases, an aneurysm may leak a slight amount of blood. This leaking (sentinel bleed) may cause only a:

• Sudden, extremely severe headache

A more severe rupture almost always follows leaking.

Unruptured aneurysm
An unruptured brain aneurysm may produce no symptoms, particularly if it's small. However, a large unruptured aneurysm may press on brain tissues and nerves, possibly causing:

• Pain above and behind an eye
• A dilated pupil
• Change in vision or double vision
• Numbness, weakness or paralysis of one side of the face
• A drooping eyelid

When to see a doctor
A ruptured aneurysm is a medical emergency. In about 30 percent of cases, ruptured brain aneurysms are fatal.

Seek immediate medical attention if you develop a:

• Sudden, extremely severe headache

If you're with someone who complains of a sudden, severe headache or who loses consciousness or has a seizure, call 911 or your local emergency number.


Causes:

Brain aneurysms develop as a result of thinning and degenerating artery walls. Aneurysms often form at forks or branches in arteries because those sections of the vessel are weaker. Although aneurysms can appear anywhere in the brain, they are most common in arteries at the base of the brain.

Complications:

When a brain aneurysm ruptures, the bleeding usually lasts only a few seconds. The blood can cause direct damage to surrounding cells, and the bleeding can damage or kill other cells. It also increases pressure inside the skull. If the pressure becomes too elevated, the blood and oxygen supply to the brain may be disrupted to the point that loss of consciousness or even death may occur.
Complications that can develop after the rupture of an aneurysm include:

• Re-bleeding. An aneurysm that has ruptured or leaked is at risk of bleeding again. Re-bleeding can cause further damage to brain cells.
  
• Vasospasm. After a brain aneurysm ruptures, blood vessels in your brain may narrow erratically (vasospasm). This condition can limit blood flow to brain cells (ischemic stroke) and cause additional cell damage and loss.
  
• Hydrocephalus. When an aneurysm rupture results in bleeding in the space between the brain and surrounding tissue (subarachnoid hemorrhage) — most often the case — the blood can block circulation of the fluid surrounding the brain and spinal cord (cerebrospinal fluid). This condition can result in hydrocephalus, an excess of cerebrospinal fluid that increases pressure on the brain and can damage tissues.
  
• Hyponatremia. Subarachnoid hemorrhage from a ruptured brain aneurysm can disrupt the balance of sodium in the blood supply. This may occur from damage to the hypothalamus, an area near the base of the brain. A drop in blood sodium levels (hyponatremia) can lead to swelling of brain cells and permanent damage.

Treatments and drugs:


Surgery
There are two common treatment options for a ruptured brain aneurysm.

• Surgical clipping is a procedure to close off an aneurysm. The neurosurgeon removes a section of your skull to access the aneurysm and locates the blood vessel that feeds the aneurysm. Then he or she places a tiny metal clip on the neck of the aneurysm to stop blood flow to it.
  
• Endovascular coiling is a less invasive procedure than surgical clipping. The surgeon inserts a hollow plastic tube (catheter) into an artery, usually in your groin, and threads it through your body to the aneurysm. He or she then uses a guide wire to push a soft platinum wire through the catheter and into the aneurysm. The wire coils up inside the aneurysm, disrupts the blood flow and causes blood to clot. This clotting essentially seals off the aneurysm from the artery.

Both procedures pose risks, particularly bleeding in the brain or loss of blood flow to the brain. The endovascular coil is less invasive and may be initially safer, but it also has a higher risk of subsequent re-bleeding, and additional procedures may be necessary. Your neurosurgeon will make a recommendation based on the size of the brain aneurysm, your ability to undergo surgery and other factors.

Other treatments
Other treatments for ruptured brain aneurysms are aimed at relieving symptoms and managing complications.

• Pain relievers, such as acetaminophen (Tylenol, others), may be used to treat headache pain.
  
• Calcium channel blockers prevent calcium from entering cells of the blood vessel walls. These medications may lessen vasospasm, the erratic narrowing of blood vessels that may be a complication of a ruptured aneurysm. One of these medications, nimodipine, has been shown to reduce the risk of delayed brain injury caused by insufficient blood flow after subarachnoid hemorrhage of a ruptured aneurysm.
  
• Interventions to prevent stroke from insufficient blood flow include intravenous injections of a drug called a vasopressor, which elevates blood pressure to overcome the resistance of narrowed blood vessels. An alternative intervention to prevent stroke is angioplasty. In this procedure, a surgeon uses a catheter to inflate a tiny balloon that expands a narrowed blood vessel in the brain. A catheter may also be used to deliver to the brain a drug called a vasodilator, which causes blood vessels to expand.
  
• Anti-seizure medications may be used to treat seizures related to a ruptured aneurysm. These medications include levetiracetam (Keppra), phenytoin (Dilantin, Phenytek, others) and valproic acid (Depakene).
  
• Ventricular or lumbar draining catheters and shunt surgery can lessen pressure on the brain from excess cerebrospinal fluid (hydrocephalus) associated with a ruptured aneurysm. A catheter may be placed in the spaces filled with fluid inside of the brain (ventricles) or surrounding your brain and spinal cord to drain the excess fluid into an external bag. Sometimes, it may then be necessary to introduce a shunt system — which consists of a flexible silicone rubber tube (shunt) and a valve — that creates a drainage channel starting in your brain and ending in your abdominal cavity.
  
• Rehabilitative therapy. Damage to the brain from a subarachnoid hemorrhage usually results in the need for physical, speech and occupational therapy to relearn skills.

Treating unruptured brain aneurysms
Surgical clipping or endovascular coiling can be used to seal off an unruptured brain aneurysm and help prevent a future rupture. However, the known risks of the procedures may outweigh the potential benefit.

A neurologist and a neurosurgeon can help you determine whether the treatment is appropriate for you. Factors that they would consider in making a recommendation include:

• The size and location of the aneurysm
• Your age and general health
• Family history of ruptured aneurysms
• Congenital conditions that increase the risk of a ruptured aneurysm

If you have high blood pressure, talk to your doctor about medication to manage the condition. If you have a brain aneurysm, proper control of blood pressure may lower the risk of rupture.