TBI is a sudden injury from an external force that affects the functioning of the brain. It can be caused by a bump or blow to the head (closed head injury) or by an object penetrating the skull (called a penetrating injury).
Some TBIs result in mild, temporary problems, but a more severe TBI can lead to serious physical and psychological symptoms, coma, and even death.
TBI includes (but is not limited to) several types of injury to the brain:
- Skull fracture occurs when the skull cracks. Pieces of broken skull may cut into the brain and injure it, or an object such as a bullet may pierce the skull and enter the brain.
- Contusion is a bruise of the brain, in which swollen brain tissue mixes with blood released from broken blood vessels. A contusion can occur from the brain shaking back and forth against the skull, such as from a car collision or sports accident or in shaken baby syndrome.
- Intracranial hematoma occurs when damage to a major blood vessel in the brain or between the brain and the skull causes bleeding.
- Anoxia absence of oxygen to the brain, causes damage to the brain tissue.
The most common form of TBI is concussion. A concussion can happen when the head or body is moved back and forth quickly, such as during a motor vehicle accident or sports injury. Concussions are often called “mild TBI” because they are usually not life-threatening. However, they still can cause serious problems, and research suggests that repeated concussions can be particularly dangerous.
A person who has a TBI may have some of the same symptoms as a person who has a non-traumatic brain injury. Unlike TBI, this type of injury is not caused by an external force, but is caused by an internal problem, such as a stroke or infection. Both types of injury can have serious, long-term effects on a person’s cognition and functioning.
TBI can happen to anyone, but certain groups face a greater risk for TBI than others. TBI among members of the military has become a particular concern in recent years because many military personnel in Iraq and Afghanistan have been exposed to such TBI hazards as improvised explosive devices. Head and neck injuries, including severe brain trauma, have been reported in 1 out of 4 military members who were evacuated from those conflicts.
Symptoms of a TBI
TBI symptoms vary depending on the extent of the injury and the area of the brain affected. Some symptoms appear immediately; others may appear several days or even weeks later. A person with TBI may or may not lose consciousness—loss of consciousness is not always a sign of severe TBI.
Symptoms of Mild TBI
A person with a mild TBI may experience:
- Blurred vision
- Ringing in the ears
- Tiredness or sleepiness
- A bad taste in the mouth
- A change in sleep habits
- Behavior or mood changes
- Trouble with memory, concentration, attention, or thinking
- Loss of consciousness lasting a few seconds to minutes
- Sensitivity to light or sound
- Nausea or vomiting
Symptoms of Moderate or Severe TBI
A person with moderate or severe TBI may have some of the symptoms listed above. In addition, the person may experience any of the following:
- Headache that gets worse or won’t go away
- Repeated vomiting or nausea
- Slurred speech
- Convulsions or seizures
- An inability to wake up from sleep
- Enlargement of the pupil (dark center) of one or both eyes
- Numbness or tingling of arms or legs
- Loss of coordination
- Increased confusion, restlessness, or agitation
- Loss of consciousness lasting a few minutes to hours3
A person who suffers a blow to the head or another trauma that may have caused a TBI should seek medical attention
Risk Factors for TBI
According to the CDC, approximately 1.7 million people experience a TBI in the U.S. each year. This number does not include injuries seen at military or Veterans Health Administration health facilities.
Anyone can experience TBI because it is caused by common events such as car crashes, sports injuries, and falls.
Causes of a TBI
A TBI is caused by an external force that injures the brain. It can occur when a person’s head is hit, bumped, or jolted. It also can occur when an object, such as a bullet, pierces the skull, or when the body is shaken or hit hard enough to cause the brain to slam into the skull. The leading causes of TBI are falls, motor vehicle crashes and traffic-related incidents, collisions with an object, and assaults. Half of TBI incidents involve alcohol use.
Sports and recreational activities are also a significant cause of TBI, especially among young people. The activities associated with the greatest number of emergency department visits for TBI include bicycling, football, playground activities, basketball, and soccer.
In the military, the leading causes of TBI are bullets, fragments, blasts, falls, motor vehicle crashes, and assaults.
Some causes of TBI are avoidable. The list below offers some ways to help prevent TBI.
- Always wear a seat belt when riding in a motor vehicle.
- Make sure a child in a car is protected with a child safety seat and/or seat belt.
- Never drive while under the influence of alcohol or drugs.
- Wear a helmet and make sure children wear the appropriate helmets for such activities as bike-riding, skateboarding, and playing certain sports.
- Make living areas safer for older people with measures such as removing rugs and other tripping hazards and improving lighting throughout the home.
- Install window guards to keep young children from falling out of windows, and use safety gates at the top and bottom of stairs when young children are around.
- Avoid falls by using a step-stool with a grab bar to reach objects on high shelves; installing handrails on stairways.
- Make sure the surface on your child's playground is made of shock-absorbing material (e.g., hardwood mulch, sand).
Diagnosing a TBI
To diagnose TBI, health care providers may use one or more tests that assess a person’s physical injuries, brain and nerve functioning, and level of consciousness. Some of these tests are described below.
Glascow Coma Scale (GCS)
The GCS measures a person’s functioning in three areas:
- Ability to speak, such as whether the person speaks normally, speaks in a way that doesn't make sense, or doesn't speak at all
- Ability to open eyes, including whether the person opens his or her eyes only when asked
- Ability to move, ranging from moving one’s arms easily to not moving even in response to painful stimulation
A health care provider rates a person’s responses in these categories and calculates a total score. A score of 13 and higher indicates a mild TBI, 9 through 12 indicates a moderate TBI, and 8 or below indicates severe TBI.1 However, there may be no correlation between initial GCS score and the person’s short- or long-term recovery or abilities.
Measurements for Level of TBI
Health care providers sometimes rank the person’s level of consciousness, memory loss, and GCS score.
A TBI is considered mild if:
- The person was not unconscious or was unconscious for less than 30 minutes.
- Memory loss lasted less than 24 hours.
- The GCS was 13 to15.
A TBI is considered moderate if:
- The person was unconscious for more than 30 minutes and up to 24 hours.
- Memory loss lasted anywhere from 24 hours to 7 days.
- The GCS was 9 to 12.
A TBI is considered severe if:
- The person was unconscious for more than 24 hours.
- Memory loss lasted more than 7 days.
- The GCS was 8 or lower.
Speech and Language Tests
- A speech-language pathologist completes a formal evaluation of speech and language skills, including an oral motor evaluation of the strength and coordination of the muscles that control speech, understanding and use of grammar and vocabulary, as well as reading and writing.
- Social communication skills are evaluated with formal tests and role-playing scenarios.
- If a patient has problems with swallowing, the speech-language pathologist will make recommendations regarding management and treatment to ensure that the individual is able to swallow safely and receive adequate nutrition.
Cognition and Neuropsychological Tests
- Cognition describes the processes of thinking, reasoning, problem solving, information processing, and memory.
- Most patients with severe TBI suffer from cognitive disabilities, including the loss of many higher level mental skills.
- Neuropsychological assessments are often used to obtain information about cognitive capabilities.
- These tests are specialized task-oriented evaluations of human brain-behavior relationships, evaluating higher cognitive functioning as well as basic sensory-motor processes.
- Testing by a neuropsychologist can assess the individual's cognitive, language, behavioral, motor, and executive functions and provide information regarding the need for rehabilitative services.
- For this assessment, a neuropsychologist reviews the case history and hospital records of the patient, and interviews the patient and his/her family.
- The neuropsychologist acquires information about the “person” the individual was before the injury, based on aspects like school performance, habits, and lifestyle, in order to detail which abilities remain unchanged as well as areas of the brain that are adversely affected by the injury and how the injury is expected to impact the individual’s life.
Health care providers may also use tests that take images of a person’s brain. These include, but are not limited to:
- Computerized tomography (CT). A CT (or “cat”) scan takes X-rays from many angles to create a complete picture. It can quickly show bleeding in the brain, bruised brain tissue, and other damage.
- Magnetic resonance imaging (MRI). MRI uses magnets and radio waves to produce more detailed images than CT scans. An MRI likely would not be used as part of an initial TBI assessment because it takes too long to complete. It may be used in follow-up examinations, though.
- Intracranial pressure (ICP) monitoring. Sometimes, swelling of the brain from a TBI can increase pressure inside the skull. The pressure can cause additional damage to the brain. A health care provider may insert a probe through the skull to monitor this swelling. In some cases, a shunt or drain is placed into the skull to relieve ICP.
Tests for Assessing TBI in Military Settings
A severe trauma may be obvious in a military situation, but a milder TBI may not be as easy to identify. The U.S. Department of Defense and Department of Veterans Affairs have therefore established procedures to assess quickly whether the person suffered:
- A loss of consciousness
- Memory problems
- Neurologic symptoms, such as confusion or poor coordination
This assessment, combined with other measures, helps determine the type of care necessary, including evacuation for a higher level of treatment.
Possible Effects of TBI
The effects of TBI range in duration and seriousness, depending on the extent of the injury and its location. According to the CDC, nearly 45% of people who are hospitalized after a TBI have a related disability one year after the injury.
Sometimes, a person will have medical complications as a result of TBI, and the risk of these problems increases with the severity of the injury. Some complications of TBI include seizures, nerve damage, blood clots, contraction of a blood vessel, stroke, coma, and infections in the brain.1 The risks of many of these problems decrease as more time passes from the initial TBI and as the person’s condition stabilizes.
Longer-term Effects of TBI
TBI may cause problems with various brain functions. The types and extent of these problems depend on where the brain was injured.
Possible problems from TBI include:
- Cognition, such as difficulty learning, remembering, making decisions, and reasoning
- Senses, such as double vision, a consistent bitter taste in the mouth or a loss of the sense of taste, ringing in the ears, and tingling or pain
- Communication, such as trouble talking, reading, writing, and explaining feelings or thoughts
- Behavior, including difficulty with social situations, relationships, and self-control, or aggression
- Emotions, including depression, anxiety, mood swings, and irritability
Degenerative Effects of TBI
Research suggests that having one or more TBIs may increase the risk of diseases that cause the degeneration, or break down, of brain cells. Some evidence indicates that TBI is associated with:
- Alzheimer’s disease, which impairs memory, emotions, and thinking skills
- Parkinson’s disease, which causes the loss of motor skills and control over motor skills
- Chronic traumatic encephalopathy which often affects athletes involved in sports with head impacts, including boxing, football, and hockey, and causes problems with memory, thinking, and motor skills
Reference: National Institutes of Child Health and Human Development