Brain & Nervous System Health Center

Brain Swelling

If you bump your knee, it's likely to swell. But what if you injure your brain?

Swelling -- also called edema -- is the body's response to many types of injury. It can result from overuse or infection. Usually, swelling happens quickly and is simple to treat with some combination of rest, ice, elevation, medication, or removal of excess fluid.

Your brain can also swell as a result of injury, illness, or other reasons. Brain swelling, though, can quickly cause serious problems -- including death. It's also usually more difficult to treat. As your body's master control system, the brain is critical to overall function. Yet, the thick, bony skull that snugly protects this vital organ provides little room for the brain to swell.

What Is Brain Swelling?

Brain swelling goes by many names:

  • Brain edema
  • Elevated intracranial pressure
  • Cerebral edema

Swelling can occur in specific locations or throughout the brain. It depends on the cause. Wherever it occurs, brain swelling increases pressure inside the skull. That's known as intracranial pressure, or ICP. This pressure can prevent blood from flowing to your brain, which deprives it of the oxygen it needs to function. Swelling can also block other fluids from leaving your brain, making the swelling even worse. Damage or death of brain cells may result.

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What Causes Brain Swelling?

Injury, other health problems, infections, tumors, and even high altitudes -- any of these problems can cause brain swelling to occur. The following list explains different ways the brain can swell:

  • Traumatic brain injury (TBI): A TBI is also called a head injury, brain injury, or acquired brain injury. In TBI, a sudden event damages the brain. Both the physical contact itself and the quick acceleration and deceleration of the head can cause the injury. The most common causes of TBI include falls, vehicle crashes, being hit with or crashing into an object, and assaults. The initial injury can cause brain tissue to swell. In addition, broken pieces of bone can rupture blood vessels in any part of the head. The body's response to the injury may also increase swelling. Too much swelling may prevent fluids from leaving the brain.
  • Ischemic strokes: Ischemic stroke is the most common type of stroke and is caused by a blood clot or blockage in or near the brain. The brain is unable to receive the blood -- and oxygen -- it needs to function. As a result, brain cells start to die. As the brain responds, swelling can occur.
  • Brain (intracerebral) hemorrhages and strokes: Hemorrhage refers to blood leaking from a blood vessel. Hemorrhagic strokes are the most common type of brain hemorrhage. They occur when blood vessels anywhere in the brain rupture. As blood leaks and the body responds, pressure builds inside the brain. High blood pressure is thought to be the most frequent cause of this kind of stroke. Hemorrhages in the brain can also be due to head injury, certain medications, and unknown malformations present from birth.
  • Infections: Illness caused by an infectious organism such as a virus or bacterium can lead to brain swelling. Examples of these illnesses include:
    • Meningitis: This is an infection in which the covering of the brain becomes inflamed. It can be caused by bacteria, viruses, other organisms, and some medications.
    • Encephalitis: This is an infection in which the brain itself becomes inflamed. It is most often caused by a group of viruses and is spread usually through insect bites. A similar condition is called encephalopathy, which is due to Reye's syndrome.
    • Toxoplasmosis: This infection is caused by a parasite. Toxoplasmosis most often affects fetuses, young infants, and people with damaged immune systems.
    • Subdural empyema: Subdural empyema refers to an area of the brain becoming abscessed or filled with pus, usually after another illness such as meningitis or a sinus infection. The infection can spread quickly, causing swelling and blocking other fluid from leaving the brain.
  • Tumors: Growths in the brain can cause swelling in several ways. As a tumor develops, it can press against other areas of the brain. Tumors in some parts of the brain may block cerebrospinal fluid from flowing out of the brain. New blood vessels growing in and near the tumor can also lead to swelling.
  • High altitudes: Although researchers don't know the exact causes, brain swelling is more likely to occur at altitudes above 4,900 feet. This type of brain edema is usually associated with severe acute mountain sickness (AMS) or high-altitude cerebral edema (HACE).

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What Are the Symptoms of Brain Swelling?

Symptoms of brain swelling vary, depending on the severity and the cause. Usually they begin suddenly. You may notice any of these symptoms:

How Is Brain Swelling Diagnosed?

The steps used by your doctor to diagnose brain swelling depend on the symptoms and the suspected cause. Common exams and tests used in the diagnosis include:

  • Head and neck exam
  • Neurologic exam
  • CT scan of the head to identify the extent and location of the swelling
  • MRI of the head to identify the extent and location of the swelling
  • Blood tests to check for causes of the swelling

What Is the Treatment for Brain Swelling?

Minor cases of brain swelling due to causes such as moderate altitude sickness or a slight concussion often resolve within a few days. In most cases, however, more treatment is needed quickly.

The goal is to assure that the brain receives enough blood and oxygen to remain healthy while the swelling is relieved and any underlying causes are treated. This may require a combination of medical and surgical treatments. Prompt treatment usually results in quicker and more complete recovery. Without it, some damage may remain.

Treatment for brain edema may include any combination of the following:

  • Oxygen therapy: Providing oxygen through a respirator or other means helps make sure that the blood has enough oxygen in it. The doctor can adjust the respirator to help reduce the amount of swelling.
  • IV fluids: Giving fluids and medicine through an IV can keep blood pressure from dropping too low. This helps to make sure that the body -- including the brain -- is receiving enough blood. However, some fluids can make swelling worse. Doctors attempt to use the right amounts of the right fluids in someone with brain swelling.
  • Lowering body temperature (hypothermia): Lowering the temperature of the body and brain helps relieve swelling and allows the brain to heal. Hypothermia as a treatment for brain swelling is not widely used because it is difficult to perform correctly.
  • Medication: In some cases of brain edema, your doctor may start a drug to help relieve the swelling. Medication may also be given for other reasons, such as to slow your body's response to the swelling or to dissolve any clots. The drugs your doctor gives you depend on the cause and symptoms of brain swelling.
  • Ventriculostomy: In this procedure, a surgeon cuts a small hole in the skull and inserts a plastic drain tube. Cerebrospinal fluid is drained from inside the brain, helping to relieve the pressure.
  • Surgery: Surgery may have one or more of these goals:
    • Removing part of the skull to relieve intracranial pressure; this procedure is called decompressive craniectomy.
    • Removing or repairing the source of the swelling, such as repairing a damaged artery or vein or removing a growth

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What Are the Long-Term Effects of Brain Swelling?

It's common to have lingering effects from brain swelling. The problems you notice depend on the severity as well as the location of the injury. Symptoms may be noticed with any of the following:

Your health care team is available to help you deal with these challenges. While some problems may continue to diminish over time, others may require ongoing treatment.

How Can I Protect my Head?

To protect the brain, keep these tips in mind as you go about your daily activities:

  • Use a helmet when biking, skating, playing contact sports, or performing other activities in which you might fall and hit your head.
  • Wear seat belts properly when driving or riding in vehicles.
  • Make sure you are doing all you can to control high blood pressure and heart disease.
  • Avoid smoking.
  • When traveling to high elevations, take your time -- allow your body to adjust to the altitude.
WebMD Medical Reference Reviewed by Neil Lava, MD on September 20, 2014

Sources

SOURCES:

MedicineNet.com: "Definition of Cerebral Edema."

Hutchinson, P. Neurosurgery Focus, 2007; vol 22(5): p E14.

eMedicine.com: "Classification and Complications of Traumatic Brain Injury;" "Stroke, Ischemic;" "Stroke, Hemorrhagic;" "Cerebellar Hemorrhage;" "Pediatrics, Reye Syndrome;" "Toxoplasmosis;" "Acute Disseminated Encephalomyelitis;" Subdural Empyema;" "Cerebral Venous Thrombosis;" and "Altitude Illness - Cerebral Syndromes."

WebMD Medical Reference from Healthwise: "Meningitis - Topic Overview."

 

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