Traumatic brain injury: Causes, symptoms, and diagnosis

Traumatic brain injury can happen when a sudden, violent blow or jolt to the head results in damage to the brain. In the United States and elsewhere, it is a major cause of disability and death.

As the brain collides with the inside of the skull, there may be bruising of the brain, tearing of nerve fibers and bleeding. If the skull fractures, a broken piece of skull may penetrate the brain tissue.

Causes include falls, sports injuries, gunshot wounds, physical aggression, and road traffic accidents.

The Centers for Disease Control and Prevention (CDC) define a TBI as “a disruption in the normal function of the brain that can be caused by a bump, blow, or jolt to the head, or penetrating head injury.”

The severity of symptoms will depend on which part of the brain is affected, whether it is in a specific location or over a widespread area, and the extent of the damage.

In mild cases, temporary confusion and headache may occur. Serious TBI can result in unconsciousness, amnesia, disability, coma, and death or long-term impairment.

The CDC estimate that, in 2013, TBI contributed to the deaths of some 50,000 people. In 2012, 329,290 people aged under 19 years sought emergency treatment for a TBI resulting from a sporting or recreational activity.

Parents, guardians, and teachers should ensure that children are properly supervised and that they wear appropriate safety equipment during sporting and other activities.

A head injury or suspected TBI needs medical attention.

Fast facts on traumatic brain injury

The effect of a TBI, such as concussion, depends on the severity of the injury and where it occurs.

It is a major cause of death and disability in the United States and worldwide.

Causes include falls, road traffic accidents, and sports injuries.

Symptoms include confusion, persistent headaches, convulsions, and memory loss.

Anyone who receives a head injury, however mild, should consider seeking medical attention.


head injury
A head injury can lead to cognitive impairment.

Signs and symptoms may appear at once, within 24 hours, or they may emerge days or weeks after the injury. Sometimes the symptoms are subtle. A person may notice a problem but not relate it to the injury. Some people will appear to have no symptoms after a TBI, but their condition worsens later.

The effects can be physical and psychological.

The initial physical effects include bruising and swelling. Increased pressure in the brain can cause:

damage to brain tissue, as it presses against the skull or as one part of the brain pushes into another

pressure on blood vessels, reducing their ability to supply the brain cells with oxygen and essential nutrients

Internal bleeding

Signs of internal bleeding include bruising behind the ears (battle sign) or around the eyes (raccoon eyes). These can potentially indicate a severe or life-threatening injury. They need immediate medical attention.

Other signs that may indicate severe injury include:

a loss of consciousness

convulsions or seizures

repeated vomiting

slurred speech

weakness or numbness in the arms, legs, hands, or feet


loss of coordination

dilated pupils

inability to wake up from sleep

severe headache

weakness and numbness in hands, feet, arms or legs

The following signs and symptoms can also indicate a need for urgent attention:


changes in mood

memory problems

inability to remember what happened before or after the incident

fatigue (tiredness) and lethargy

getting lost easily

persistent headaches

persistent pain in the neck

slowness in thinking, speaking, reading or acting

moodiness, for example, suddenly feeling sad or angry for no apparent reason

sleep pattern changes, such as sleeping more or less than usual, or having trouble sleeping

light headedness, dizziness

becoming more easily distracted

increased sensitivity to light or sounds

loss of sense of smell or taste


tinnitus, or ringing in the ears

These may appear at once, within hours, or later. A person who has received a TBI but who appears to have no symptoms should be closely monitored for 24 hours, as signs of injury may not be immediate.

Anyone who experiences the above symptoms even days or weeks after a TBI should see a doctor.

[Child with headache]
A child with a TBI may become irritable and listless.

Children will have the same signs and symptoms, but they may be less likely to let others know how they feel.

If an infant has received a blow or jolt to the head and any of the following signs or symptoms occur, call a doctor:

changes in sleeping patterns

irritability and crying


loss of balance

loss of newly acquired skills, such as toilet training

changes in playing behavior changes

refusal to eat

loss of interest in favorite activities or toys


unsteady walking


If these signs are noticed, the child should see a doctor.

In sport, the participant should leave out the game and not play again until the doctor gives permission to return, whether or not they lose consciousness. Not every TBI or concussion involves a loss of consciousness.

Repeated head injuries in rapid succession can be particularly harmful to the brain in the long term.

It is important to monitor a person who has had a TBI because their condition can deteriorate rapidly and symptoms that appear mild can become severe.

Long-term effects

There is growing evidence that a TBI or repeated TBIs can have long-term effects on health, including an increased risk of dementia and other neurological and neurodegenerative disorders. Football players with high scores on tests for depression have also been found to have a larger number of concussions.

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[Brain scan showing cerebellum in red]
Swelling of the brain within the skull can put undue pressure on the surrounding tissues.

In a mild case of TBI, symptoms normally go away without treatment. However, repeated, mild TBIs can be dangerous or fatal. This is why it is essential to rest and avoid further exposure until a doctor gives the go-ahead.

More severe cases will require hospitalization, possibly with intensive care.

Emergency care aims to stabilize the patient’s condition and prevent any worsening of brain damage.

This will involve ensuring the airway is open, providing ventilation and oxygen, and maintaining blood pressure.

Medications may be used to help control symptoms.

Sedation: This can help prevent agitation and excess muscle activity and contribute to pain relief. Examples include profanol.

Pain relief: Opioids may be used.

Diuretics: These increase urine output and reduce the amount of fluid in tissue. These are administered intravenously. Mannitol is the most commonly used diuretic for TBI patients.

Anti-seizure medication: A person who has experienced moderate to severe TBI may have seizures for up to a week after the incident. Medication may help prevent further brain damage that may result from a seizure.

Coma-inducing medications: During a coma, a person needs less oxygen. Sometimes, a coma may be deliberately induced coma if the blood vessels are unable to supply adequate amounts of food and oxygen to the brain.


Surgery may be necessary in some cases.

Removing a hematoma: Internal bleeding can cause partly or fully clotted blood to pool in some part of the brain, worsening the pressure on the brain tissue. Emergency surgery can remove a hematoma from between the skull and the brain, reducing pressure inside the skull and preventing further brain damage.

Repairing a skull fracture: Any part of the skull that is fractured and pressing into the brain will need to be surgically repaired. Skull fractures that are not pressing into the brain normally heal on their own. The main concern with a skull fracture is that forces strong enough to cause it may have caused further, underlying damage.

Creating an opening in the skull: This can relieve the pressure inside the skull if other interventions have not worked.

Long-term treatment

A person who experiences a severe TBI may need rehabilitation.

Depending on the extent and type of their injury, they may need to relearn how to walk, talk, and carry out other everyday tasks.

This may include treatment in a hospital or in a specialized therapy center. It can involve a physical therapist, an occupational therapist, and others, depending on the type of injury.

Tips for recovery

Tips that can aid recovery:

Avoid activities that could cause another blow or jolt to the head.

Follow the instructions of healthcare professionals.

Do not take drugs that the physician has not approved.

Do not return to normal activities, including driving and sports participation, until the doctor agrees.

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