Swelling of the brain


Cerebral Edema: What You Need to Know About Brain Swelling

Anyone with a brain injury is at risk for cerebral edema. Here’s everything you need to know about symptoms, treatment, and prevention of this condition.

Cerebral edema, or brain swelling, is an increase of pressure in your head that may disrupt the blood-brain barrier. Alamy

If you bump your elbow, you can simply apply ice and the swelling will disappear. But what happens when you hit your head, and your brains starts to swell?

Cerebral edema, or brain swelling, is an increase of pressure in your head that may disrupt the blood-brain barrier. It is the body’s way of responding to trauma, stroke, or infection. Because the brain is encased in a rigid skull, increased intracranial pressure, or ICP, can prevent oxygen-rich blood from flowing to the brain, block fluids from leaving the brain, and even damage or kill brain cells. (1)

A person suffering from cerebral edema may experience uncomfortable symptoms, like a headache, nausea, memory loss, or loss of consciousness. (2)

Cerebral edema is a life-threatening condition that can cause permanent brain damage or death if not treated quickly.

What Causes Your Brain to Swell?

Head trauma, infections, and a number of other neurological conditions can cause the brain to swell as pressure increases and compresses brain tissue. The typical causes of brain swelling include:

  • Traumatic Brain Injury (TBI) A TBI is a blow to the head that can result in bleeding, bruising, or swelling of the brain. Common causes of TBI include falls, car crashes, sports, domestic violence, or combat injuries. The increase in intracranial pressure can cause brain tissue to swell. (3,4)
  • Infections A few different types of infections can result in brain swelling, including encephalitis and meningitis. Encephalitis is inflammation of the brain typically caused by a viral infection. It can lead to headache, fever, loss of consciousness, seizures, and more. Meningitis is an infection of the meninges that surround the brain and spinal cord. Typical causes include viral, bacterial, parasitic, or fungal infections.
  • Tumors A brain tumor is an abnormal growth of cells inside the brain or skull. It can compress or displace brain tissue or block cerebrospinal fluid, which can increase pressure and cause swelling. (5)
  • Stroke About 80 percent of strokes are ischemic strokes caused by blockages in the arteries in the brain, which in turn prevent oxygenated blood from reaching brain cells. Injured brain cells typically swell and can block the drainage of cerebrospinal fluid from the brain, driving pressure even higher. (6,7)
  • Brain Hemorrhage An intracranial hemorrhage is bleeding within or around the brain, and a hemorrhagic stroke involves death of brain cells as a result of a ruptured or torn blood vessel in the brain. Both of these conditions can cause brain swelling. (8)
  • High Altitudes You can develop high-altitude cerebral edema (HACE) about two days after from climbing above 4,000 meters (13,123 feet). This type of brain swelling occurs alongside acute mountain sickness (AMS), ataxia (loss of control of body movements), fatigue, and altered mental state. It can progress to a coma or death within 24 hours if not treated. (9)

Types of Brain Swelling

There are five main types of cerebral edema. The type a person may be suffering from is dependent on the cause of injury.

  • Cytotoxic This type of cerebral edema is the most common form of cerebral edema, and it results from an accumulation of sodium and water within the cells that leads to cellular failure. The main causes of this type of edema include traumatic brain injury, metabolic disease, infections like encephalitis or meningitis, or the ingestion of chemicals like methanol or ecstasy. (1,2)
  • Vasogenic If you have a stroke, there’s a chance your brain could swell due to a blood clot or a lack of oxygen. This causes a disruption of the blood-brain barrier that allows fluid to leak and pressure to build inside the brain. This form of cerebral edema is most commonly seen in people with brain tumors, but it can also be caused by too much carbon dioxide in the blood, metabolic disease, lead toxicity, and high altitude cerebral edema (HACE). (10)
  • Interstitial The main cause of this type of edema is obstructive hydrocephalus, which is the accumulation of cerebrospinal fluid from an abnormal widening of the ventricles that increases pressure in the brain. Obstructive hydrocephalus results from a genetic defect, developmental disorder, meningitis, tumor, traumatic brain injury, or hemorrhage. (11)
  • Hydrostatic Hydrostatic edema is the accumulation of interstitial fluid, which is the fluid in between the small, narrow spaces between tissues. Chronic venous obstruction or heart failure can elevate capillary hydrostatic pressure and cause the brain to swell. (12,13)
  • Osmotic “Cells have water inside and outside, and water can pass through their semipermeable membranes,” says Ram Balu, MD, PhD, an assistant professor of neurology at the University of Pennsylvania in Philadelphia. “This process is called osmosis. Sometimes, there can be a buildup of electrolytes inside the cell, and this causes a high concentration of water to move into the cells.” This imbalance osmolality is usually caused by serum osmolality from inappropriate antidiuretic hormone (SIADH) secretion or a TBI and leads to abnormal pressure, fluid, and swelling in the brain. (1)

Signs and Symptoms to Look Out For

“Generally, suspected edema is not the symptom that will bring someone into the hospital,” says Dr. Balu. “People will either have a TBI, a stroke, or experience a range of neurological symptoms before brain swelling is determined. Cerebral edema is a consequence of an underlying condition.”

The symptoms of cerebral edema vary widely based on the cause and can be extremely painful. Patient age, brain size, and edema location can also affect symptom severity. Typical signs of brain swelling include:

  • Headache is the most common symptom any time the brain starts to swell, according to Balu.
  • Dizziness
  • Nausea
  • Mood changes, such as depression, anxiety, or aggression as a result of a brain injury (14)
  • Memory loss
  • Altered consciousness
  • Seizure
  • Intoxication
  • Lack of coordination
  • Intestinal obstruction (volvulus, intussusception)
  • Numbness or weakness that can be generalized or localized. For example, if the brain swelling is caused by a tumor and swelling on the left side of the brain, you could experience weakness or numbness on the right side of the body, Balu says.
  • Double visión due to inability to fully move one of your eyes in a particular direction
  • Macrocephaly (children with a head circumference greater than the 98th percentile) (2)

How Doctors Diagnose Brain Swelling

“If a patient comes in with a TBI, stroke, or acute brain injury, there’s almost always brain swelling,” says Balu. “They’ll be immediately admitted to the ICU, and then we perform a neurological and physical exam.” According to Balu, “the clinical neurological exam tests brain function and level of consciousness to see if there’s brain damage.” Any slight change in level of consciousness may indicate brain damage. (15)

“Signs we look out for include increases in intracranial pressure in the head, sleepiness, responsiveness, and problems with vision,” Balu says. Health providers may also look at:

  • Mentation The ability to focus, comprehend, and remember information
  • Motor Function The ability to coordinate and execute movements
  • Sensory Function Level of pain and sense of touch, sight, and sound
  • Vital Signs and Patterns of Breathing
  • Pupillary Function How your pupils react to light (15)

When a person is admitted to the hospital for a brain injury, sometimes neurologists will place a device directly into the brain itself to monitor intracranial pressure, Balu says.

“Next, we’ll do either a scan to see what’s causing the swelling and neurological symptoms and where it’s located. We’ll either perform a CT scan or an MRI, but often we do MRIs because they tell us more about the brain swelling and give us a picture of the type of neurological problem, whether it’s a stroke, bleeding, or tumor.”

Treatment Options for Cerebral Edema

Those who are experiencing brain swelling should be closely monitored during the first 48 to 72 hours after the injury or infection. The speed at which a patient receives treatment can affect recovery and improve outcome. (15)

“Once we determine what’s going on, patients will be monitored in the hospital for complications from the swelling itself, and we’ll treat the neurological condition that’s causing the edema,” Balu says. “Treatment is dictated by the type of neurologic injury.”

According to Balu, if the cause is cytotoxic, doctors will look to reverse the underlying medical condition first, with acute treatments — for example, an intravenous (IV) delivery of hypertonic saline that increase electrolytes in the blood and pulls water out of the brain. “Same for bleeding in the brain or TBI. We don’t necessarily treat the swelling right away because it’s less of a concern. Though in extreme cases, we’ll have our colleagues do a craniectomy and take a portion of the skull off to let the brain swell out.” And if a patient comes in with acute symptoms of a stroke, Balu says they first work to get blood flow to the brain, Balu says.

Once cerebral edema has been diagnosed through a scan, a doctor may help relieve pressure by:

  • Keeping the hospital bed elevated 30 or 45 degrees. According to Balu, when the head is flat, it can increase pressure in the brain, so it’s best to keep the head up.
  • Maintaining normal body temperature with antipyretics
  • Maintaining a calm environment with low lighting to avoid agitation
  • Monitoring fluid and electrolyte levels
  • Administering anticonvulsants for seizure prevention
  • Prescribing pain relievers to increase comfort
  • Draining CSF fluid by inserting a catheter into the ventricle
  • Administering neuromuscular blockades
  • Offering hyperosmolar therapy (2,15)

In extreme cases, your doctor may consider a craniectomy to relieve pressure. Controlled hyperventilation, high-dose barbiturate therapy, and moderate hypothermia are other treatments for reducing swelling. (2,15)

According to Balu, initial treatment of brain swelling are often drugs, like:

Alternative interventions and medication may be issued to treat the underlying cause of your cerebral edema, such as if you had a stroke, diabetic ketoacidosis, or metabolic disease.

If left untreated, cerebral edema can lead to permanent brain damage or result in a wide range of complications, like vision loss, headaches, cerebral atrophy, cognitive decline, altered mental status, depression, sleep problems, epilepsy, or even brain death. (2)

How to Prevent Cerebral Edema

Preventing cerebral edema involves taking measures to protect your head. Some options include:

  • Using a helmet during sports or physical activities to prevent unexpected brain injury
  • Controlling your blood pressure and cholesterol to prevent heart disease and stroke
  • Wearing seat belts when traveling in a vehicle
  • Slowly ascending to high elevations to avoid HACE
  • Avoiding smoking to reduce the oxidative and inflammatory risk for stroke. (15)
  • Monitoring your blood pressure and cholesterol to reduce your risk of a stroke.

Intracranial hypertension

Causes of chronic intracranial hypertension

Possible causes of chronic intracranial hypertension (IH) include:

  • a blood clot on the surface of your brain, known as a chronic subdural haematoma
  • a brain tumour
  • an infection in your brain, such as meningitis or encephalitis
  • hydrocephalus, where fluid builds up around and inside your brain
  • abnormal blood vessel, such as an arteriovenous fistula or arteriovenous malformation
  • a blood clot in one of the veins of your brain, known as a venous sinus thrombosis

Rare causes include a blockage in the circulation of fluid at the bottom of the skull (Chiari malformation), inflammation of the blood vessels in the brain (vasculitis) and abnormal skull growth in children (craniosynostosis).

Idiopathic IH

In many cases, the cause of chronic IH is unclear. This is known as idiopathic IH, or sometimes benign IH.

It mainly affects women in their 20s and 30s, and has been associated with:

  • being overweight or obese – most cases happen in overweight women, although it’s not clear why
  • hormone problems such as Cushing’s syndrome, hypoparathyroidism, an underactive thyroid (hypothyroidism) or an overactive thyroid (hyperthyroidism)
  • certain medicines including some antibiotics, steroids and the combined contraceptive pill
  • a lack of red blood cells (iron deficiency anaemia) or too many red blood cells (polycythaemia)
  • chronic kidney disease
  • lupus – a problem with the immune system

But these are only linked with idiopathic IH, they’re not necessarily causes.

Cerebral Edema

Brain swelling can become a life-threatening condition. It should be treated immediately. Treatment options are meant to restore blood flow and oxygen to the brain while reducing the swelling.

It’s also important to treat the underlying cause to prevent any further damage.

There are six common treatment options.

1. Medication

Depending on the severity of your condition and the underlying cause, doctors may prescribe you medication to help reduce swelling and prevent blood clots.

2. Osmotherapy

When your brain swells, it accumulates excess fluid. Osmotherapy is a technique meant to draw water out of the brain. This is done using osmotic agents such as mannitol, or high-salt saline. Osmotic therapy also helps improve blood circulation. This will help reduce swelling and ICP in the skull.

3. Hyperventilation

Some doctors may perform a controlled hyperventilation to help lower your ICP. Hyperventilation causes you to exhale more than you inhale, lowering the amount of carbon dioxide in your bloodstream. Proper blood flow in your brain is dependent upon carbon dioxide. Controlling this process lowers the blood flow in your brain and reduces ICP.

4. Hypothermia

Another treatment method includes inducing hypothermia. Lowering the body temperature decreases metabolism in the brain and can also reduce swelling.

Though there’ve been some success stories with this method, controlled hypothermia is still being researched.

5. Ventriculostomy

This is a more invasive procedure that involves draining fluid from the brain. A doctor will make a small incision in the skull and insert a tube as a drain. This method will relieve ICP pressure.

6. Surgery

In more severe cases of cerebral edema, you may need surgery to relieve ICP. This surgery could mean removing part of the skull or removing the source of the swelling, such as in the case of a tumor.

Brain Swelling

What is brain swelling?

A variety of conditions are known to cause brain swelling, which is enlargement of the brain due to excessive fluid collection in the chambers, or ventricles, of the brain or the accumulation of fluid within the brain tissue itself.

Excess fluid in the ventricles of the brain leads to a condition known as hydrocephalus. The fluid exerts outward pressure on the brain tissue, pressing it into the skull. In the skull of an infant or small child, where there are soft areas known as fontanelles and sutures between the bony plates that have not yet hardened, the head can increase in size.

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Fluid collection within the brain tissue, called cerebral edema, can result from numerous causes, including infections, trauma, stroke, brain tumors, certain toxic substances, complications of diabetes, chemical imbalances, abuse of opioids, extreme high blood pressure (malignant hypertension), or high altitude sickness.

Symptoms of brain swelling include headache, dizziness, nausea, numbness or weakness, loss of coordination or balance, loss of the ability to see or speak, seizures, lethargy, memory loss, incontinence, or altered level of consciousness. In infants, the fontanelles (“soft spots”) may bulge, the head may increase in size, cries may be high-pitched or shrill, and irritability or feeding difficulties may occur.

Brain swelling causes ongoing damage to the brain tissue, so it needs to be treated as quickly as possible to save as much brain tissue as possible. Seek immediate medical care (call 911) for head trauma, significant high altitude sickness, high fever accompanied by neck stiffness or rigidity, severe headache, known ingestion of toxins, bites from poisonous animals or insects, or symptoms suggestive of brain swelling.

What other symptoms might occur with brain swelling?

Brain swelling may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the brain may also involve other body systems.

Symptoms of infection that may occur along with brain swelling

Brain swelling may occur as a result of an infection. Other symptoms suggestive of infection that are known to cause brain swelling include:

  • Confusion or loss of consciousness

  • Fever

  • Gait abnormality

  • Headache

  • Imbalance

  • Malaise or lethargy

  • Neck stiffness or rigidity

  • Rash

  • Seizures

Symptoms of chemical imbalances or toxic exposures that may occur along with brain swelling

Brain swelling may occur as a result of toxic exposures or chemical imbalances. Other symptoms of toxic exposures or chemical imbalances that could accompany brain swelling include:

  • Abdominal pain

  • Abnormal heart rhythm such as rapid heart rate (tachycardia) or slow heart rate (bradycardia)

  • Confusion or loss of consciousness

  • Difficulty breathing or rapid breathing

  • Difficulty speaking

  • Dry skin or changes in skin color

  • Feeling very thirsty

  • Frequent urination

  • Fruity breath

  • Hallucinations

  • Muscle weakness

  • Nausea with or without vomiting

Other symptoms that may occur along with brain swelling

Depending upon the age of the individual and the cause of the swelling, brain swelling may accompany other symptoms including:

  • Bulging of the soft spots on top of the head (fontanelles) in infants or small children

  • Difficulty with memory, thinking, talking, comprehension, writing or reading

  • Dizziness

  • Droopy eyelid

  • Flaccid limbs

  • High-pitched or shrill cries in infants or small children

  • Impaired balance and coordination

  • Increased head size in infants or small children

  • Irritability, fussiness, poor feeding, and sleepiness in infants and young children

  • Lethargy

  • Loss of vision or changes in vision

  • Muscle weakness

  • Numbness or tingling in arms or legs

  • Paralysis

Serious symptoms that might indicate a life-threatening condition

Brain swelling may be a symptom of a life-threatening condition that should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Abnormal pupil size or nonreactivity to light

  • Change in level of consciousness or alertness such as passing out or unresponsiveness

  • Change in mental status or sudden behavior change such as confusion, delirium, lethargy, hallucinations or delusions

  • Flaccid limbs

  • Garbled or slurred speech or inability to speak

  • High fever (higher than 101 degrees Fahrenheit)

  • High-pitched, shrill cries in an infant or small child

  • Irritability, fussiness, poor feeding, and unusual sleepiness in infants and young children

  • Paralysis or inability to move a body part

  • Seizure

  • Stiff or rigid neck

  • Sudden change in vision, loss of vision, or eye pain

  • Trauma to the head

  • Worst headache of your life

What causes brain swelling?

A variety of different conditions are known to cause brain swelling, and, in some instances, the cause may not be known. Brain swelling can take two forms, hydrocephalus, in which fluid collects in the ventricles and the swelling occurs from the inside outward, and cerebral edema, in which the fluid collects in the brain tissue and the swelling is generalized.

Causes of brain swelling related to hydrocephalus

The causes of brain swelling in which excess fluid collects in the ventricles of the brain (hydrocephalus) are not always known but may include:

  • Birth defects
  • Brain or spinal cord injury
  • Brain or spinal cord tumor
  • Complications of birth
  • Cysts or tumors
  • Genetic abnormalities
  • Infection
  • Normal pressure hydrocephalus

Causes of brain swelling related to cerebral edema

Brain swelling related to cerebral edema can be caused by a number of conditions including:

  • Brain tumors
  • Chemical imbalances
  • Diabetic ketoacidosis (a life-threatening complication of diabetes)
  • Exposure to certain toxins
  • Head trauma
  • High altitude sickness
  • Infection
  • Malignant hypertension (severe high blood pressure)
  • Opioid abuse
  • Stroke

Serious or life-threatening causes of brain swelling

In some cases, brain swelling may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Brain or spinal cord injury
  • Brain or spinal cord tumor
  • Diabetic ketoacidosis (a life-threatening complication of diabetes)
  • Exposure to certain toxins
  • Head trauma
  • High altitude sickness
  • Infection
  • Malignant hypertension (severe high blood pressure)
  • Opioid abuse
  • Stroke

Questions for diagnosing the cause of brain swelling

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your brain swelling including:

  • What specific symptoms have you noticed?
  • Did anything such as an injury or illness precede the symptoms?
  • Have you checked your blood sugar?
  • Have you been exposed to any toxic substances?
  • Have you recently traveled from a low altitude to a higher altitude?
  • What medications are you taking?

What are the potential complications of brain swelling?

Because brain swelling can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Cognitive impairment
  • Developmental delay
  • Learning disability
  • Loss or alteration of sensation
  • Muscle weakness
  • Paralysis
  • Personality changes
  • Physical disability
  • Unconsciousness and coma

Increased Intracranial Pressure (ICP) Headache

How is ICP treated?

Increased intracranial pressure is an emergency. Treatment might include:

  • Medicine to reduce swelling
  • Draining extra cerebrospinal fluid or bleeding around the brain
  • Removing part of the skull (craniotomy) to ease swelling (though this is rare)

You may also be treated for the underlying cause of your intracranial pressure, which could be an infection, high blood pressure, tumor, or stroke.

What are the complications of ICP?

ICP has serious complications, such as:

  • Seizures
  • Stroke
  • Neurological damage
  • Death

Can ICP be prevented?

You can reduce your risk of certain underlying conditions that may lead to ICP such as high blood pressure, stroke or infection. If you have any of the symptoms, get medical attention immediately.

When should I call my healthcare provider?

Call your doctor or 911 if you have any of the symptoms listed:

  • Severe headache
  • Blurred vision
  • Feeling less alert than usual
  • Vomiting
  • Changes in your behavior
  • Weakness or problems with moving or talking
  • Lack of energy or sleepiness
  • Seizure

Key points about increased intracranial pressure (ICP)

  • ICP is a dangerous condition.
  • It is an emergency and requires immediate medical attention.
  • Increased intracranial pressure from bleeding in the brain, a tumor, stroke, aneurysm, high blood pressure, brain infection, etc. can cause a headache and other symptoms.
  • Treatment includes relieving the brain of the increased pressure.
  • ICP has serious complications including death.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.

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).

Scientists pinpoint brain-swelling mechanism

By turning off a single gene, scientists from the Djavad Mowafaghian Centre for Brain Health (DMCBH), a partnership of UBC and Vancouver Coastal Health, were able to successfully stop swelling in rodent brains.

Brain swelling is a gradual process that becomes life-threatening within days of the injury, and is caused by sodium chloride drawing water into the nerve cells. This swelling–known as cytotoxic edema–eventually kills brain cells.

“We’ve known for years that sodium chloride accumulation in neurons is responsible for brain swelling, but now we know how it’s getting into cells, and we have a target to stop it,” explains brain researcher Brian MacVicar, co-director of DMCBH with the Vancouver Coastal Health Research Institute and the study’s principal investigator.

The team, including Terrance Snutch, director of translational neuroscience at the DMCBH, developed several novel technological approaches to identify the cascade of events that took place within individual brain cells as they swelled.

They then switched off the expression of different genes and were able to pinpoint a single protein–SLC26A11–that acts as a channel for chloride to enter nerve cells. By turning off the chloride channel, the accumulation of fluid into the cells was halted, and nerve cells no longer died.

“It was quite a surprising result, because we had few indications as to what this protein did in the brain,” says Ravi Rungta, then a graduate student in the MacVicar lab and the paper’s lead author.

Though the technique used by the researchers to block swelling and cell death is unlikely to work quickly enough to mitigate swelling in the case of real head trauma, the discovery has provided a target for drug development.

“This discovery is significant because it gives us a specific target — now that we know what we’re shooting at, we just need the ammunition,” says MacVicar. “That’s what we’re doing now: looking for drugs to inhibit the chloride channel.”

Traumatic brain injury


Traumatic brain injury (TBI) is sudden damage to the brain caused by a blow or jolt to the head. Common causes include car or motorcycle crashes, falls, sports injuries, and assaults. Injuries can range from mild concussions to severe permanent brain damage. While treatment for mild TBI may include rest and medication, severe TBI may require intensive care and life-saving surgery. Those who survive a brain injury can face lasting effects in their physical and mental abilities as well as emotions and personality. Most people who suffer moderate to severe TBI will need rehabilitation to recover and relearn skills.

What is a traumatic brain injury?

TBI is an injury to the brain caused by a blow or jolt to the head from blunt or penetrating trauma. The injury that occurs at the moment of impact is known as the primary injury. Primary injuries can involve a specific lobe of the brain or can involve the entire brain. Sometimes the skull may be fractured, but not always. During the impact of an accident, the brain crashes back and forth inside the skull causing bruising, bleeding, and tearing of nerve fibers (Fig. 1). Immediately after the accident the person may be confused, not remember what happened, have blurry vision and dizziness, or lose consciousness. At first the person may appear fine, but their condition can decline rapidly. After the initial impact occurs, the brain undergoes a delayed trauma – it swells – pushing itself against the skull and reducing the flow of oxygen-rich blood. This is called secondary injury, which is often more damaging than the primary injury.

Figure 1. During impact to the head, the soft brain crashes back and forth against the inside of the hard skull causing bruising, bleeding, and shearing of the brain.

Traumatic brain injuries are classified according to the severity and mechanism of injury:

  • Mild: person is awake; eyes open. Symptoms can include confusion, disorientation, memory loss, headache, and brief loss of consciousness.
  • Moderate: person is lethargic; eyes open to stimulation. Loss of consciousness lasting 20 minutes to 6 hours. Some brain swelling or bleeding causing sleepiness, but still arousable.
  • Severe: person is unconscious; eyes do not open, even with stimulation. Loss of consciousness lasting more than 6 hours.

Types of traumatic brain injuries

  • Concussion is a mild head injury that can cause a brief loss of consciousness and usually does not cause permanent brain injury.
  • Contusion is a bruise to a specific area of the brain caused by an impact to the head; also called coup or contrecoup injuries. In coup injuries, the brain is injured directly under the area of impact, while in contrecoup injuries it is injured on the side opposite the impact.
  • Diffuse axonal injury (DAI) is a shearing and stretching of the nerve cells at the cellular level. It occurs when the brain quickly moves back and forth inside the skull, tearing and damaging the nerve axons. Axons connect one nerve cell to another throughout the brain, like telephone wires. Widespread axonal injury disrupts the brain’s normal transmission of information and can result in substantial changes in a person’s wakefulness.
  • Traumatic Subarachnoid Hemorrhage (tSAH) is bleeding into the space that surrounds the brain. This space is normally filled with cerebrospinal fluid (CSF), which acts as a floating cushion to protect the brain. Traumatic SAH occurs when small arteries tear during the initial injury. The blood spreads over the surface of the brain causing widespread effects.
  • Hematoma is a blood clot that forms when a blood vessel ruptures. Blood that escapes the normal bloodstream starts to thicken and clot. Clotting is the body’s natural way to stop the bleeding. A hematoma may be small or it may grow large and compress the brain. Symptoms vary depending on the location of the clot. A clot that forms between the skull and the dura lining of the brain is called an epidural hematoma. A clot that forms between the brain and the dura is called a subdural hematoma. A clot that forms deep within the brain tissue itself is called an intracerebral hematoma. Over time the body reabsorbs the clot. Sometimes surgery is performed to remove large clots.

Although described as individual injuries, a person who has suffered a TBI is more likely to have a combination of injuries, each of which may have a different level of severity. This makes answering questions like “what part of the brain is hurt?” difficult, as more than one area is usually involved.

Secondary brain injury occurs as a result of the body’s inflammatory response to the primary injury. Extra fluid and nutrients accumulate in an attempt to heal the injury. In other areas of the body, this is a good and expected result that helps the body heal. However, brain inflammation can be dangerous because the rigid skull limits the space available for the extra fluid and nutrients. Brain swelling increases pressure within the head, which causes injury to parts of the brain that were not initially injured. The swelling happens gradually and can occur up to 5 days after the injury.

What are the symptoms?

Depending on the type and location of the injury, the person’s symptoms may include:

  • Loss of consciousness
  • Confusion and disorientation
  • Memory loss / amnesia
  • Fatigue
  • Headaches
  • Visual problems
  • Poor attention / concentration
  • Sleep disturbances
  • Dizziness / loss of balance
  • Irritability / emotional disturbances
  • Feelings of depression
  • Seizures
  • Vomiting

Diffuse injuries (such as a concussion or diffuse axonal injury) will typically cause an overall decreased level of consciousness. Whereas, focal injuries (such as an ICH or a contusion) will have symptoms based on the brain area affected (Fig. 2).

Figure 2. The brain is composed of three parts: the brainstem, cerebellum, and cerebrum, which is divided into lobes. The table lists the lobes of the brain and their normal functions as well as problems that may occur when injured. While an injury may occur in a specific area, it is important to understand that the brain functions as a whole by interrelating its component parts.

Every patient is unique and some injuries can involve more than one area or a partial section, making it difficult to predict which specific symptoms the patient will experience.

What are the causes?

Common causes include falls, car or motorcycle crashes, vehicular accidents involving pedestrians, athletics, and assaults with or without a weapon.

Who is affected?

Approximately 1.5 to 2 million adults and children suffer a traumatic brain injury (TBI) each year in the United States. Most people who experience a head injury, about 1.1 million, will have a mild injury that does not require an admission to the hospital. Another 235,000 individuals will be hospitalized with a moderate to severe head injury, and approximately 50,000 will die.

How is a diagnosis made?

When a person is brought to the emergency room with a head injury, doctors will learn as much as possible about his or her symptoms and how the injury occurred. The person’s condition is assessed quickly to determine the extent of injury.

The Glasgow Coma Score (GCS) is a 15-point test used to grade a patient’s level of consciousness. Doctors assess the patient’s ability to 1) open his or her eyes, 2) ability to respond appropriately to orientation questions, (“What is your name? What is the date today?”), and 3) ability to follow commands (“Hold up two fingers, or give a thumbs up”). If unconscious or unable to follow commands, his or her response to painful stimulation is checked. A number is taken from each category and added together to get the total GCS score. The score ranges from 3 to 15 and helps doctors classify an injury as mild, moderate, or severe. Mild TBI has a score of 13-15. Moderate TBI has a score of 9-12, and severe TBI has a score of 8 and below.

Diagnostic imaging tests will be performed:

Figure 3. CT scan shows a blood clot (hematoma) collecting under the bone (red arrows) and displacing brain (yellow arrow) to the other side of the skull.

  • Computed Tomography (CT) is a noninvasive X-ray that provides detailed images of anatomical structures within the brain. A CT scan of the head is taken at the time of injury to quickly identify fractures, bleeding in the brain, blood clots (hematomas) and the extent of injury (Fig. 3). CT scans are used throughout recovery to evaluate the evolution of the injury and to help guide decision-making about the patient’s care.
  • Magnetic Resonance Imaging (MRI) is a noninvasive test that uses a magnetic field and radiofrequency waves to give a detailed view of the soft tissues of the brain. A dye (contrast agent) may be injected into the patient’s bloodstream. MRI can detect subtle changes in the brain that cannot be seen on a CT scan.
  • Magnetic Resonance Spectroscopy (MRS) gives information about the metabolism of the brain. The numbers generated from this scan provide a general prognosis about the patient’s ability to recover from the injury.

What treatments are available?

Mild TBI usually requires rest and medication to relieve headache. Moderate to severe TBI require intensive care in a hospital. Bleeding and swelling in the brain can become an emergency that requires surgery. However, there are times when a patient does not require surgery and can be safely monitored by nurses and physicians in the neuroscience intensive care unit (NSICU).

The goals of treatment are to resuscitate and support the critically ill patient, minimize secondary brain injury and complications, and facilitate the patient’s transition to a recovery environment. Despite significant research, doctors only have measures to control brain swelling, but do not have a way to eliminate swelling from occurring.

Neurocritical care
Neurocritical care is the intensive care of patients who have suffered a life-threatening brain injury. Many patients with severe TBI are comatose or paralyzed; they also may have suffered injuries in other parts of the body. Their care is overseen by a neurointensivist, a specialty-trained physician who coordinates the patient’s complex neurological and medical care. Patients are monitored and awakened every hour for nursing assessments of their mental status or brain function.

Figure 4. In the NSICU, the patient is connected to numerous machines, tubes, and monitors. The monitoring equipment provides information about body functions and helps guide care. Some equipment may take over certain functions, such as breathing, nutrition, and urination, until the patient’s body is able to do these things on its own.

Seeing a patient who has suffered a severe TBI can be shocking. It is possible that your loved one’s appearance will be altered because of facial injury and equipment that is used for monitoring. Numerous tubes, lines, and equipment may be used to closely monitor his or her heart rate, blood pressure, and other critical body functions. (Fig. 4)

Figure 5. A brain oxygen and cerebral blood flow monitor is inserted into the brain tissue and secured to the skull with a bolt. A catheter is inserted into the ventricle of the brain to monitor intracranial pressure (ICP). If pressure is too high, the CSF fluid can be drained from the ventricles.

  • Intracranial pressure (ICP) monitor. A catheter is placed through a small hole in the skull and positioned inside the ventricle (fluid-filled area deep within the brain) to measure pressure inside the head (Fig. 5). The ICP monitor allows the NSICU team to intervene quickly if the pressure becomes too high. Typical intracranial pressure is less than 20 mmHg. However, there are times when a higher number is safe and acceptable.
  • Brain oxygen monitor (Licox). A catheter is placed through a small hole in the skull and positioned within the brain tissue. The Licox measures the oxygen level and temperature within the brain. Adjustments in the amount of oxygen given to the patient are often made to maximize the brain’s oxygen level. A cerebral blood flow monitor, called a Hemedex, is a newer monitor that is placed with the Licox and helps the NSICU team evaluate blood flow through the brain.
  • Ventilator. Some patients may require a ventilator, a machine that helps them breathe. The ventilator is connected to the patient by the endotracheal tube, or ET tube. The tube is placed into the patient’s mouth and down into the trachea, or windpipe. The tube allows the machine to push air into and out of the lungs, thereby helping the patient breathe.
  • Feeding tube. When patients are on a ventilator or have a decreased level of alertness, they may not be able to eat or get sufficient nutrition to meet their needs. A nasal-gastric feeding tube may be inserted through the patient’s nose and passed down the throat into the stomach. It delivers liquid nutrition as well as any medication that is required.
  • Seizures and EEG monitoring. A seizure is an abnormal electrical discharge from the brain. Approximately 24% of patients who suffer a TBI will have a seizure that is undetected unless they are monitored by an electroencephalogram (EEG). Seizures that are not visible to the human eye are referred to as non-convulsive seizures. Because these seizures are serious, all patients with a severe TBI are monitored with continuous EEG for 24 to 72 hours after injury.


  • Sedation and pain. After a head injury it may be necessary to keep the patient sedated with medications. These medications can be turned off quickly in order to awaken the patient and check their mental status. Because patients often have other injuries, pain medication is given to keep them comfortable.
  • Controlling intracranial pressure. Hypertonic saline is a medication used to control pressure within the brain. It works by drawing the extra water out of the brain cells into the blood vessels and allowing the kidneys to filter it out of the blood.
  • Preventing seizures. Patients who’ve had a moderate to severe traumatic brain injury are at higher risk of having seizures during the first week after their injury. Patients are given an anti-seizure medication (levetiracetam or phenytoin) to prevent seizures from occurring.
  • Preventing infection. Although every attempt is made to prevent infection, the risk is always present. Any device placed within the patient has the potential to introduce a microbe. If an infection is suspected, a test will be sent to a laboratory for analysis. If an infection is present, it will be treated with antibiotics.


Surgery is sometimes necessary to repair skull fractures, repair bleeding vessels, or remove large blood clots (hematomas). It is also performed to relieve extremely high intracranial pressure.

  • Craniotomy involves cutting a hole in the skull to remove a bone flap so that the surgeon can access the brain. The surgeon then repairs the damage (e.g., skull fracture, bleeding vessel, remove large blood clots). The bone flap is replaced in its normal position and secured to the skull with plates and screws.

Figure 6. A large decompressive craniectomy is removed and the dura is opened to allow the brain to expand. Blood clots are removed and bleeding vessels are repaired. The bone flap is frozen and replaced about 6 weeks later.

  • Decompressive craniectomy involves removing a large section of bone so that the brain can swell and expand. This is typically performed when extremely high intracranial pressure becomes life threatening. At that time the patient is taken to the operating room where a large portion of the skull is removed to give the brain more room to swell (Fig. 6). A special biologic tissue is placed on top of the exposed brain and the skin is closed. The bone flap is stored in a freezer. One to 3 months after the swelling has resolved and the patient has stabilized from the injury, the bone flap is replaced in another surgery, called cranioplasty.

Other surgical procedures may be performed to aid in the patient’s recovery:

  • Tracheotomy involves making a small incision in the neck to insert the breathing tube directly into the windpipe. The ventilator will then be connected to this new location on the neck and the old tube is removed from the mouth.
  • Percutaneous Endoscopic Gastrostomy Tube (PEG) is a feeding tube inserted directly into the stomach through the abdominal wall. A small camera is placed down the patient’s throat into the stomach to aid with the procedure and to ensure correct placement of the PEG tube (see Surgical Procedures for Accelerated Recovery).

Clinical trials

Clinical trials are research studies in which new treatments—drugs, diagnostics, procedures, and other therapies—are tested in people to see if they are safe and effective. Research is always being conducted to improve the standard of medical care. Information about current clinical trials, including eligibility, protocol, and locations, are found on the Web. Studies can be sponsored by the National Institutes of Health (see clinicaltrials.gov) as well as private industry and pharmaceutical companies (see www.centerwatch.com).

Recovery & prevention

The recovery process varies depending on the severity of the injury, but typically progresses through stages: coma, confusion / amnesia, and recovery.

  • When a patient is in a coma, his or her eyes are closed and they show minimal reaction when spoken to or stimulated. Movements that may be seen at this time are basic reflexes or automatic responses to a stimulus. The brain wave activity in a comatose person is very different from that of a sleeping person.
  • When a patient begins to awaken, the first natural response is that of bodily protection. Patients at this stage will move away from any stimulus or tend to pull at items attached to them in an attempt to remove anything that is uncomfortable or irritating. His or her eyes may be open more often, but they may not be aware of their behavior or be able to interact in a meaningful way. It is common for a patient to respond to each stimulus (hearing, seeing, or touching) in the same way. Responses may include increased rate of breathing, moaning, moving, sweating, or a rise in blood pressure.
  • As the patient continues to wake up, their interactions may become more purposeful. They may look at a person and follow them around the room with their eyes, or follow simple commands such as “Hold up your thumb.” Patients tend to be confused and may have inappropriate or agitated behaviors.

Not all head injuries are the same. Patients recover at different rates and to varying degrees. It is difficult to determine at what point a patient will start understanding and interacting with their caregivers or family in a meaningful way. It is important to have patience; recovery from a brain injury can take weeks, months, or even years.

The Family’s Role
Many family members express feelings of helplessness when their loved one is in the NSICU. You are not alone. Please take care of yourself and use your energy wisely.

Visiting hours are limited in the NSICU. Too much stimulation can agitate the patient and raise his or her blood pressure. You can most effectively convey your concern by sitting quietly and holding your loved one’s hand. Be aware that the patient, though silent, may hear anything you say. Never speak as if the patient were not there.

As patients recover, they need help understanding what has happened to them during this “lost period of time.” Keep in mind that the recovery of consciousness is a gradual process – not just a matter of waking up. Progress is usually tracked in three areas: movement, thinking, and interacting. You can help by keeping a diary of their progress. Family photos may help with regaining memory.

Most patients are discharged from the hospital when their condition has stabilized and they no longer require intensive care. A social worker will work closely with the family as preparations are made for a return home or for transfer to a long-term care or rehabilitation center.

  • A long-term acute care (LTAC) facility is a place for patients who have stabilized from their initial injury but who still require a ventilator or frequent nursing care. Many patients are discharged to an LTAC to continue being weaned from the ventilator. Once off the ventilator, they can be moved to a rehabilitation or skilled nursing facility.
  • A rehabilitation facility is a place for patients who do not require a ventilator but who still require help with basic daily activities. Physical and occupational therapists work with patients to help them achieve their maximum potential for recovery. Rehab facilities are either Acute Inpatient Rehab that require patients to participate in 3 hours or more of rehab a day or a Skilled Nursing Facility (SNF) that provide 1-3 hours of rehab a day depending on what the patient can tolerate.

Recovering from a brain injury relies on the brain’s plasticity—the ability for undamaged areas of the brain to take over functions of the damaged areas. It also relies on regeneration and repair of nerve cells. And most importantly, on the patient’s hard work to relearn and compensate for lost abilities.

  • A physical therapist helps patients rebuild and maintain strength, balance, and coordination. They can work with the patient in any facility.
  • An occupational therapist helps patients to perform activities of daily living, such as dressing, feeding, bathing, toileting, and transferring themselves from one place to another. They also provide adaptive equipment if a patient has difficultly performing a task.
  • A speech therapist helps patients by monitoring their ability to safely swallow food and helping with communication and cognition.
  • A neuropsychologist helps patients relearn cognitive functions and develop compensation skills to cope with memory, thinking, and emotional needs.


Tips to reduce the risk for a head injury:

  • Always wear your helmet when riding a bicycle, motorcycle, skateboard, or all-terrain vehicle.
  • Never drive under the influence of alcohol or drugs.
  • Always wear your seat belt and ensure that children are secured in the appropriate child safety seats.
  • Avoid falls in the home by keeping unsecured items off the floor, installing safety features such as non-slip mats in the bathtub, handrails on stairways, and keeping items off of stairs.
  • Avoid falls by exercising to increase strength, balance, and coordination.
  • Store firearms in a locked cabinet with bullets in a separate location.
  • Wear protective headgear while playing sports.

Sources & links

If you have questions, please contact Mayfield Brain & Spine at 513-221-1100.

Support groups provide an opportunity for patients and their families to share experiences, receive support, and learn about advances in treatments and medications.


  1. Brain Trauma Foundation: Guidelines for the Management of Severe Traumatic Brain Injury. J Neurotrauma 24 Suppl 1:S1-106, 2007
  2. Johnson G. Traumatic Brain Injury Survival Guide, 2004. www.tbiguide.com

Brain Injury Association of America, www.biausa.org
Brain Injury Association of Ohio, www.biaoh.org
Brain Trauma Foundation, www.braintrauma.org


closed head injury: brain injury from an external impact that does not break the skull.

coma: a state of unconsciousness from which the person cannot be aroused; Glasgow Coma Scale score of 8 or less.

concussion: widespread injury to the brain caused by a hard blow or violent shaking, causing a sudden and temporary impairment of brain function, such as a short loss of consciousness or disturbance of vision and equilibrium.

contusion: a bruise to a specific area of the brain; caused by an impact and broken blood vessels.

diffuse axonal injury (DAI): injury to the nerve cell axons from rapid rotational or deceleration of the brain. DAI is often seen in motor vehicle accidents or shaking injuries. The nerve axons, which compose the white matter of the brain, are twisted or torn by shearing forces.

edema: tissue swelling caused by the accumulation of fluid.

hematoma: a blood clot.

hydrocephalus: an abnormal build-up of cerebrospinal fluid usually caused by a blockage of the ventricular system of the brain. Increased intracranial pressure can compress and damage brain tissue. Also called “water on the brain.”

intracranial pressure (ICP):pressure within the skull. Normal ICP is 20mm HG.

ischemia: a low oxygen state usually due to obstruction of the arterial blood supply or inadequate blood flow in the tissue.

open head injury: penetration of the skull pushing skull fragments or objects (bullet) into the brain.

ventricles: hollow areas in the center of the brain containing cerebrospinal fluid. There are four ventricles: two lateral ventricles (one on each side of the brain), the third ventricle, and the fourth ventricle.

updated > 7.2018
reviewed by > Dale Horne, MD, PhD, Michael Kachmann, MD, Mayfield Clinic, Cincinnati, Ohio

Mayfield Certified Health Info materials are written and developed by the Mayfield Clinic. We comply with the HONcode standard for trustworthy health information. This information is not intended to replace the medical advice of your health care provider.

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