Cerebral edema facts for kids

Kids Encyclopedia Facts

Quick facts for kids Cerebral edema
Synonyms	Brain edema, Cerebral oedema, Brain swelling

Skull MRI (T2 flair) of a brain metastasis with accompanying edema
Symptoms	Headache, nausea, vomiting, decreased consciousness, seizures
Similar conditions	ischemic stroke, subdural hematoma, epidural hematoma, intracerebral hematoma, intraventricular hemorrhage, subarachnoid hemorrhage, hydrocephalus, traumatic brain injury, brain abscess, brain tumor, hyponatremia, hepatic encephalopathy
Frequency	Lua error in Module:PrevalenceData at line 4: attempt to index field 'wikibase' (a nil value).

Cerebral edema is when too much fluid builds up in the brain. This extra fluid can be inside or outside the brain cells. It's like a sponge soaking up too much water.

When this happens, it can make it hard for your brain to work properly. It also increases pressure inside your skull. This pressure can push on brain tissue and blood vessels.

Symptoms can include headaches, feeling sick, throwing up, or feeling very sleepy. Sometimes, it can cause seizures or problems with vision. In very serious cases, it can lead to a coma.

Brain swelling can happen after many types of brain injuries. These include strokes, head injuries, or brain tumors. It can also be caused by infections or low salt levels in the blood. Doctors diagnose it using symptoms and brain scans like CT or MRI.

Treatment for brain swelling depends on what caused it. It often involves watching the patient closely. Doctors might use special medicines or even surgery. Brain swelling is a big reason for brain damage. It can be very serious, especially after strokes or head injuries.

What Are the Signs of Brain Swelling?

The signs of brain swelling depend on what caused it. They also depend on how much fluid has built up. But generally, they are linked to a quick rise in pressure inside the skull.

Your skull is a hard, fixed space. So, extra fluid can push on important brain parts. It can also squeeze blood vessels and the fluid around your brain. This is explained by something called the Monro-Kellie doctrine.

High pressure inside the skull is a serious emergency. Signs include headaches, nausea, and throwing up. You might also feel less awake or aware. Vision problems like blurry sight or dizziness can also happen.

Sometimes, your body tries to fight this pressure. Your blood pressure might go up to keep blood flowing to your brain. If this happens with slow heart rate and odd breathing, it's called the Cushing reflex. This reflex means the brain is being squeezed. It can lead to less blood flow to the brain, which is very dangerous.

What Causes Brain Swelling?

Brain swelling often happens after sudden brain injuries. Here are some common causes:

Head injuries
Strokes
Brain tumors
Infections, like a brain abscess or meningitis
Liver problems (hepatic encephalopathy)
Low sodium levels in the blood (hyponatremia)
Swelling from high altitudes

Things That Increase Risk

Many common brain problems can lead to brain swelling. The risk factors depend on the cause. For example, in strokes, some things make early brain swelling more likely:

Being younger
Having more severe stroke symptoms
Signs of current brain damage on exam
Feeling less awake
Certain signs on CT scans
Higher blood sugar levels

Types of Brain Swelling

Doctors usually divide brain swelling into two main types: cytotoxic and vasogenic. This helps them decide on the best treatment. But there are other types too, like interstitial, osmotic, and hydrostatic edema. Sometimes, a person can have several types at once.

Here are the main types:

Cytotoxic Edema

Cytotoxic edema is often linked to brain cell damage. It happens when brain cells swell up too much. For example, after a stroke, blood flow decreases. This means cells don't get enough energy.

When cells run out of energy, their pumps stop working. These pumps usually keep sodium out of the cells. So, sodium builds up inside. Water then rushes into the cells, making them swell. This can cause the cells to die. The main sign of this type is that the cells themselves swell.

You might see cytotoxic edema in:

Head injuries
Bleeding in the brain
The early stages of a stroke
Severe liver failure, where toxins like ammonia build up. Ammonia makes brain cells swell.
Exposure to certain toxic chemicals.
Lack of oxygen to the brain.

Vasogenic Edema

Vasogenic edema happens when the blood–brain barrier becomes leaky. The blood–brain barrier is like a protective wall around your brain. It's made of special cells joined tightly together.

If this barrier gets damaged, fluid, salts, and proteins can leak out. They go into the space between brain cells. This extra fluid increases brain volume and pressure. This leads to the symptoms of brain swelling.

Vasogenic edema can be seen in:

Brain tumors
Infections like meningitis or encephalitis
Inflammatory brain diseases
Bleeding in the brain
Head injuries
Later stages of a stroke
High blood pressure emergencies
Damage from radiation therapy.

Ionic (Osmotic) Edema

In ionic edema, the brain has a higher concentration of certain substances than the blood. This creates an imbalance. Water then moves into the brain through a process called osmosis. The blood-brain barrier is still intact here.

This can happen if:

You get too much fluid through an IV that's not balanced correctly.
You drink too much water, or your body holds onto too much water.
Blood sugar levels drop too fast, like in diabetes.
Sodium levels in the blood become very low (hyponatremia).

Interstitial Edema

Interstitial edema is often seen in a condition called hydrocephalus. This is when there's a blockage in the flow of cerebrospinal fluid (CSF). CSF is the fluid that cushions your brain and spinal cord.

When CSF can't flow properly, pressure builds up. This pressure pushes CSF out of its normal pathways. It then leaks into the spaces between brain cells. This fluid is similar to CSF.

Hydrostatic Edema

Hydrostatic edema is usually caused by very high blood pressure. When blood pressure is too high, water and small substances can be pushed out of blood vessels. They go into the brain tissue. The blood-brain barrier is usually still working. The amount of swelling depends on how high the blood pressure is.

Brain Swelling from High Altitudes

If you go to high altitudes too quickly, you might not get enough oxygen. This can lead to altitude sickness. A severe form is called high-altitude cerebral edema (HACE).

HACE happens when fluid leaks from tiny blood vessels in the brain. This is due to low oxygen affecting the blood-brain barrier. It's a type of vasogenic edema. Symptoms include feeling confused and having trouble walking straight.

To prevent altitude sickness, climb slowly. Medicines like acetazolamide can also help. If symptoms get worse, you must go down to a lower altitude right away.

Brain Swelling from Tumors

This type of brain swelling is common in people with brain tumors. It's a serious problem. It happens because the blood-brain barrier is damaged. This leads to vasogenic edema.

Cancer cells in the brain might release a substance called VEGF. This substance can make the blood-brain barrier leaky. Doctors sometimes use medicines like steroids to help reduce this swelling.

How Do Doctors Diagnose Brain Swelling?

Brain swelling is common in many brain injuries. So, it can be tricky to know how much it's affecting someone. Doctors watch patients very closely. They check how awake they are and if they have new problems. Often, patients need to be in the intensive care unit (ICU).

If brain swelling causes high pressure and pushes on the brain, it's an emergency. Doctors need to act fast to prevent more damage or even death. Catching brain swelling early and treating it quickly can save lives.

Doctors use these methods to diagnose brain swelling:

Brain Scans

Doctors use brain scans like CT and MRI. These scans help them see if there's bleeding, large growths, or hydrocephalus. They also show how much swelling there is. Scans can even give clues about the type of swelling.

CT scans are often used first. They are quick and widely available. But sometimes, MRI scans are better. MRI can tell the difference between cytotoxic and vasogenic edema. This helps guide treatment.

Monitoring Pressure Inside the Skull

Measuring the pressure inside the skull (ICP) is very important. Especially for people with head injuries. Doctors might recommend ICP monitoring if a patient is very sleepy or has abnormal CT scans.

For other brain injuries, there are no clear rules for ICP monitoring. But many doctors suggest it if there's a risk of high pressure. Early monitoring helps doctors make treatment decisions. It can also spot dangerous brain squeezing early.

How Is Brain Swelling Treated?

The main goal of treatment is to control the pressure inside the skull. Doctors also want to make sure the brain gets enough blood and oxygen. They also try to balance the fluid and salt levels.

General Ways to Help

Head Position

It's important to position the head correctly. This helps blood flow out of the brain. It also lowers pressure from the fluid around the brain. Doctors usually raise the head of the bed to about 30 degrees. This helps blood flow to the brain and controls pressure. Also, avoid tight neckwear that could block blood flow.

Breathing and Oxygen

Low oxygen and high carbon dioxide in the blood can make brain swelling worse. They make blood vessels in the brain widen. Doctors try to avoid this. If someone is very sleepy, they might need a breathing tube. This helps keep oxygen and carbon dioxide levels normal.

Fluid Management

Keeping the right amount of fluid in the body is key. Doctors avoid dehydration. They also avoid fluids that could make brain swelling worse. They try to keep blood salt levels normal or a bit high. Special salt solutions can help reduce brain swelling.

Blood pressure needs to be high enough to keep blood flowing to the brain. Medicines can help keep blood pressure stable.

Seizure Prevention

Seizures can make brain swelling worse. They can also increase pressure in the skull. Doctors might use medicines to treat seizures. Sometimes, they use them to prevent seizures, but this depends on the situation.

Fever Control

Fever can increase the brain's need for oxygen. This can make blood flow to the brain increase and raise pressure. So, keeping body temperature normal is important. Doctors might use fever-reducing medicines or cooling methods.

Blood Sugar Control

High blood sugar can make brain injury and swelling worse. It's linked to poorer outcomes. Doctors try to keep blood sugar levels normal.

Sedation

Pain and agitation can increase pressure in the skull. Doctors use pain medicines to keep patients comfortable. If a patient needs a breathing tube, they will get sedatives. Some sedatives can also help control pressure and reduce brain activity.

Nutrition

People with brain injuries need good nutrition. Feeding through a tube is often preferred. Doctors pay attention to the type of food given. They want to avoid anything that could worsen brain swelling.

Specific Treatments

While general treatments help, the best treatment depends on the cause of the swelling.

Osmotic Therapy

This treatment aims to draw water out of the brain. It works by making the blood more concentrated with salts. This pulls water from the brain into the blood vessels. The water can then be removed by the body.

Hypertonic saline is a strong salt solution given through an IV. It works quickly to reduce pressure. It can last for several hours. It's often very effective.
Mannitol is another medicine that draws water out of the brain. It also helps blood flow better. A common side effect is low blood pressure.

Steroids

Medicines like dexamethasone (a type of steroid) can help stabilize the blood-brain barrier. They are mainly used for swelling caused by brain tumors or radiation. Steroids are not helpful for strokes or head injuries. They can also have side effects, so doctors use them carefully.

Hyperventilation

Breathing faster can lower carbon dioxide in the blood. This makes blood vessels in the brain narrow. This can reduce pressure. But this effect is short-lived. Too much hyperventilation can reduce blood flow too much. This could cause a stroke. So, doctors use it carefully and for short times.

Barbiturates

Doctors can use strong medicines called barbiturates to put a patient into a coma. This can help reduce very high pressure that doesn't respond to other treatments. But these medicines have risks. They can lower blood pressure and weaken the immune system.

Cooling the Body

Controlling body temperature can reduce the brain's need for oxygen. In adults with head injuries, cooling the body might help. But for children, it might not be helpful and can even be risky. Cooling can cause serious side effects like infections. So, it's usually only used in special cases.

Surgery

Since the skull is a fixed space, surgery can help. Doctors might remove a piece of the skull bone. This allows the swollen brain to expand. This surgery is called a decompressive craniectomy. It can reduce the risk of death. However, it doesn't always improve how well a person recovers.

The best time for surgery is often before the brain is severely squeezed. Surgery can have complications. These include infection or needing a breathing tube or feeding tube afterward.

What Are the Outcomes?

Brain swelling is a serious problem after brain injuries. It's a major cause of death and long-term problems.

Brain swelling causes death in about 5% of all stroke patients. For large strokes with swelling, the death rate is about 20-30%. Swelling usually appears a few days after a stroke. Large strokes can lead to very bad swelling. If not treated aggressively, the death rate can be 50-80%. People with brain swelling after a stroke often have worse recovery.
Mild head injuries are very common. But even mild brain swelling after a head injury can increase the risk of death in the hospital. This is true for all levels of head injury. Swelling, both early and later, is linked to worse recovery. Children with head injuries and brain swelling also have worse outcomes.

How Common Is Brain Swelling?

It's hard to say exactly how common brain swelling is. This is because it happens with so many different brain problems. But it's seen in most cases of head injuries, brain tumors, strokes, and bleeding in the brain.

For example, one study found brain swelling in 28% of stroke patients. Another study found it in 22.7% of stroke cases. Overall, about 31% of people affected by strokes develop brain swelling.

In head injuries, brain swelling was found in over 60% of cases with large lesions. It was also seen in 15% of cases that looked normal on the first CT scan.

Research on Brain Swelling

Scientists are still learning about how brain swelling happens. Especially after head injuries or bleeding in the brain. Current treatments help reduce pressure. But it's not always clear how much they help with long-term recovery. Also, treatments can affect people differently. This depends on things like age, type of injury, and genes.

There are many tiny pathways in the body that cause brain swelling. Many of these are still unknown. Researchers believe future treatments will come from understanding these pathways better. Improving brain scans and other tests is also important.

Scientists have also studied the physical properties of brain swelling. They use computer models to understand how pressure changes. Other research looks at how heat moves through brain tissue. This is related to how much water is in the tissue.