Causes and effects of traumatic brain injury (TBI)
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.
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.
- 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.
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
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.
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.
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.
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.
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.
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.
- Get plenty of rest.
It is important to follow the doctor's instructions after a TBI, because the impact of a brain injury can be severe, and it is not always immediately apparent.
There are two major types of TBI: open and closed. In open TBI, the skull is broken. In a close TBI, it is not.
Further classifications include:
Concussion: A direct impact trauma that may or may not involve a loss of consciousness. This is the most common type of TBI. It is often mild, but it can be fatal.
Contusion: When a direct blow causes localized bleeding in the brain, possibly resulting in a blood clot.
Diffuse axonal injury: When tears occur in the brain structure due to shearing by the skull.
Penetrating injury: When a sharp object enters the brain.
TBIs can result from a range of incidents, from falls to collisions in sport.
TBI is caused by a severe jolt or blow to the head, or a head injury that penetrates and disrupts normal brain function.
The human brain is protected from jolts and bumps by the cerebrospinal fluid around it. The brain floats in this fluid inside the skull.
A violent blow or jolt to the head can push the brain against the inner wall of the skull, which can lead to the tearing of fibers and bleeding in and around the brain.
According to the CDC, the leading causes of TBI in the U.S. in 2013 were:
- Falls: Responsible for 47 percent of reported cases, notably in children aged up to 14 years and adults aged over 65 years
- Motor vehicle accidents: These accounted for 14 percent of cases, especially in the 15 to 19-year age group.
- Being struck by or colliding with an object: 15 percent of TBIs resulted from a collision with either a moving or stationery object.
Other causes include domestic violence and work-related and industrial accidents.
Apart from the immediate dangers, a TBI can have long-term consequences and complications.
Seizures: These may occur during the first week after the injury. TBIs do not appear to increase the risk of developing epilepsy, unless there have been major structural brain injuries.
Infections: Meningitis can occur if there is a rupture in the meninges, the membranes around the brain. A rupture can allow bacteria to get in. If the infection spreads to the nervous system, serious complications can result.
Nerve damage: If the base of the skull is affected, this can impact the nerves of the face, causing paralysis of facial muscles, double vision, problems with eye movement, and a loss of the sense of smell.
Cognitive problems: People with moderate to severe TBI may experience some cognitive problems, including their ability to:
- focus, reason, and process information
- communicate verbally and nonverbally
- judge situations
- remember things in the short term
- solve problems
- organize their thoughts and ideas
Personality changes: These may occur during recovery and rehabilitation. The patient's impulse control may be altered, resulting in inappropriate behavior. Personality changes can cause stress and anxiety for family members, friends, and caregivers.
Problems with the senses: These may lead to:
- tinnitus, or ringing in the ears
- difficulty recognizing objects
- clumsiness, due to poor hand-eye coordination
- double vision and blind spots
- sensing bad smells or a bitter taste
Coma: Patients who enter a coma and remain in a comatose state for a long time may eventually wake up and resume normal life, but some people will wake up with long-term problems and disabilities. Some people do not wake up at all.
A severe TBI is a medical emergency. Rapid diagnosis and treatment can prevent potentially life-threatening complications.
The Glasgow Coma Scale
The Glasgow Coma Scale (GCS) is commonly used to assess the likelihood and severity of brain damage following a head injury.
Scores are given according to verbal responses, physical responses and how easily the person can open their eyes.
- do not open
- open in response to pain
- open in response to voice
- open spontaneously
- makes no response
- makes incomprehensible sounds
- utters words or phrases
- speaks but is confused and disoriented
- communicates normally
Motor or physical response
- makes no movement
- extends arm in response to pain
- flexes arm in response to pain
- moves away in response to pain
- can pinpoint where the pain is
- obeys commands to move a part of the body
The score will be added together, and brain injury will be classified as follows:
- Coma, if the score is 8 or less
- Moderate, if the score is from 9 to 12
- Minor, if the score is 13 or more
People who score 13 to 15 on the scale when they enter the hospital are normally expected to have a good outcome.
Brain imaging is essential for assessing the internal damage.
Angiography may be used to detect any blood vessel problems, for example, after a penetrating head trauma.
Electroencephalography (EEG) measures the electrical activity within the brain. The results can show if a patient is having non-convulsive seizures.
Intracranial pressure monitoring enables the doctor to measure the pressure inside the skull. It can reveal any swelling of brain tissue.
Neurocognitive tests can help assess any loss of memory or ability to process thoughts.
Patients or caregivers should ensure that health providers know of any medications the person normally takes, especially blood thinners, such as warfarin (Coumadin), as these can increase the risk of complications.
Some tips can reduce the risk of a TBI.
Never drink and drive.
- Always use a seat belt when driving or traveling in a car
- Children should use a suitable restraint for their age and size
- Never drive after drinking alcohol
- Use a helmet when playing sports or using a vehicle where an incident could involve a head injury
- Instal grab bars in a bathroom that is used by older people
- Use nonslip mats on floors that can get wet
- Remove trip hazards, such as loose carpets and trailing wires
- Install window guards and safety gates on stairs if there are children around
- Ensure that play areas are made of a shock-absorbing surface, such as wood mulch
- Store any firearms, unloaded, in a locked safe or cabinet, and keep the bullets in a different location
Special care should be taken when supervising young children or older adults. Household adaptations, such as ramps and window guards, may be necessary.
The American Academy of Family Physicians recommends that everyone should go to a doctor after a blow to the head. If someone else hits their head and is behaving in an unusual way, the person who notices it should contact a doctor.
The Heads Up project offers advice and training on how to prevent or deal with a TBI and its effects.