Traumatic Brain Injury

Traumatic brain injury (TBI) happens when a sudden trauma causes damage to the brain. Everyone is at risk for TBI, but children and older adults are especially vulnerable.

Traumatic Brain Injury Overview

Reviewed: May 22, 2014

Traumatic brain injury (TBI) is a form of acquired brain injury that occurs when a sudden trauma causes damage to the brain. TBI can result when the head suddenly and violently hits an object or when an object pierces the skull and enters brain tissue. Not all blows or jolts to the head result in a TBI. The severity of a TBI may range from “mild,” which usually involves a brief change in mental status or consciousness, to “severe,” which includes an extended period of unconsciousness or amnesia after the injury.

TBI is a serious public health problem in the United States and TBIs contribute to a substantial number of deaths and cases of permanent disability. Every year, millions of people in the U.S. suffer brain injuries. More than half are bad enough that people must go to the hospital. The worst injuries can lead to permanent brain damage or death. Half of all TBIs are from motor vehicle accidents. Military personnel in combat zones are also at risk for TBIs.

Symptoms of a TBI may not appear until days or weeks following the injury. A concussion is the mildest type of TBI. It can cause a headache or neck pain, nausea, ringing in the ears, dizziness, and tiredness. People with a moderate or severe TBI may have those, plus other, symptoms, including a headache that gets worse or does not go away, repeated vomiting or nausea, convulsions or seizures, inability to awaken from sleep, slurred speech, weakness or numbness in the arms and legs, and dilated eye pupils.

Healthcare professionals use a neurological exam and imaging tests to assess TBI. Serious traumatic brain injuries need emergency treatment. Treatment and outcome depend on how severe the injury is. TBI can cause a wide range of changes affecting thinking, sensation, language, or emotions. TBI can be associated with post-traumatic stress disorder. People with severe injuries usually need rehabilitation.

Traumatic Brain Injury Symptoms

Symptoms of a TBI can be mild, moderate, or severe, depending on the extent of the damage to the brain. Some signs or symptoms may appear immediately after the traumatic event, while others may appear days or weeks later.

A person with a mild TBI may remain conscious or may experience a loss of consciousness for a few seconds or minutes. Other symptoms of mild TBI include:

  • loss of consciousness for a few seconds to a few minutes
  • no loss of consciousness, but a state of being dazed, confused or disoriented
  • headache
  • confusion
  • lightheadedness
  • dizziness or loss of balance
  • blurred vision or tired eyes
  • ringing in the ears
  • bad taste in the mouth
  • fatigue or lethargy
  • a change in sleep patterns
  • behavioral or mood changes
  • feeling depressed or anxious
  • trouble with memory, concentration, attention, or thinking

A person with a moderate or severe TBI may show the same symptoms as a mild TBI but may also have the following symptoms:

  • loss of consciousness from several minutes to hours
  • a headache that gets worse or does not go away
  • repeated vomiting or nausea
  • convulsions or seizures
  • an inability to awaken from sleep
  • dilation of one or both pupils of the eyes
  • slurred speech
  • weakness or numbness in the extremities
  • loss of coordination
  • increased confusion
  • restlessness
  • agitation or combative behavior

Traumatic Brain Injury Causes

TBI is caused by a blow or other traumatic injury to the head or body. The degree of damage can depend on several factors, including the nature of the event and the force of impact.

Injury may include one or more of the following factors:

  • damage to brain cells may be limited to the area directly below the point of impact on the skull
  • a severe blow or jolt can cause multiple points of damage because the brain may move back and forth in the skull
  • a severe rotational or spinning jolt can cause the tearing of cellular structures
  • a blast, as from an explosive device, can cause widespread damage
  • an object penetrating the skull can cause severe, irreparable damage to brain cells, blood vessels, and protective tissues around the brain
  • bleeding in or around the brain, swelling, and blood clots can disrupt the oxygen supply to the brain and cause wider damage

Common events causing traumatic brain injury include the following:

  • falls
  • vehicle-related collisions
  • violence, such as gunshot wounds, domestic violence, or child abuse
  • injuries from sports, such as soccer, boxing, football, baseball, lacrosse, skateboarding, hockey, and other high-impact or extreme sports, particularly in youth
  • explosive blasts and other combat injuries

Traumatic Brain Injury Diagnosis

TBIs are usually emergencies and consequences can worsen without treatment, doctors usually need to assess the situation rapidly.

A 15-point test, called the Glasgow Coma Scale, helps a doctor or other emergency medical personnel assess the initial severity of a brain injury by checking a person's ability to follow directions and move their eyes and limbs. The coherence of speech also provides important clues. Abilities are scored numerically, and higher scores mean less severe injuries.

Answers to the following questions will also be beneficial in judging the severity of injury:

  • How did the injury occur?
  • Did the person lose consciousness?
  • How long was the person unconscious?
  • Did you observe any other changes in alertness, speaking, coordination or other signs of injury?
  • Where was the head or other parts of the body struck?
  • Can you provide any information about the force of the injury? For example, what hit the person's head, how far did he or she fall, or was the person thrown from a vehicle?
  • Was the person's body whipped around or severely jarred?

Emergency personnel may also use imaging tests to assess a TBI. A computerized tomography (CT) scan uses a series of X-rays to create a detailed view of the brain. A CT scan can quickly visualize fractures and uncover evidence of bleeding in the brain (hemorrhage), blood clots (hematomas), bruised brain tissue (contusions) and brain tissue swelling. Magnetic resonance imaging (MRI) uses powerful radio waves and magnets to create a detailed view of the brain. This test may be used after the person's condition has been stabilized.

Tissue swelling from a TBI can increase pressure inside the skull and cause additional damage to the brain. Doctors may insert a probe through the skull to monitor this pressure.

Living With Traumatic Brain Injury

Approximately half of severely head-injured patients will need surgery to remove or repair hematomas (ruptured blood vessels) or contusions (bruised brain tissue). Disabilities resulting from a TBI depend upon the severity of the injury, the location of the injury, and the age and general health of the individual. People who experience a TBI may also have an increased risk of infection, blood vessel damage, and nerve damage. Some common disabilities include problems with cognition (thinking, memory, and reasoning), sensory processing (sight, hearing, touch, taste, and smell), communication (expression and understanding), and behavior or mental health (depression, anxiety, personality changes, aggression, acting out, and social inappropriateness). More serious head injuries may result in an unresponsive state, but one in which an individual can be aroused briefly by a strong stimulus, such as sharp pain; a coma, a state in which an individual is totally unconscious, unresponsive, unaware, and unarousable; a vegetative state, in which an individual is unconscious and unaware of his or her surroundings, but continues to have a sleep-wake cycle and periods of alertness; and a persistent vegetative state, in which an individual stays in a vegetative state for more than a month.

A TBI may also increase the risk of diseases that result in the gradual degeneration of brain cells and gradual loss of brain functions, though this risk cannot yet be determined with any certainty for an individual. These include:

  • Alzheimer's disease, which primarily causes the progressive loss of memory and other thinking skills
  • Parkinson's disease, a progressive condition that causes movement problems, such as tremors, rigidity and slow movements
  • Dementia pugilistica, which is most often associated with repetitive blows to the head in career boxing and causes symptoms of dementia and movement problems

If you experience a TBI, you can aid your recovery by following these steps.

  • Get lots of rest. Do not rush back to daily activities such as work or school.
  • Avoid doing anything that could cause another blow or jolt to the head.
  • Ask your health care professional when it's safe to drive a car, ride a bike, or use heavy equipment, because your ability to react may be slower after a brain injury.
  • Take only the drugs your health care professional has approved, and do not drink alcohol until your health care professional says it's OK.
  • Write things down if you have a hard time remembering.
  • Re-learn skills that were lost. Your health care professional can help arrange for these services.

Traumatic Brain Injury Treatments

Treatment for TBI depends on the severity of the injury.

Mild TBIs usually require no treatment other than rest and over-the-counter pain relievers to treat a headache. However, a person with a mild TBI usually needs to be monitored closely at home for any persistent, worsening, or new symptoms. He or she also may have follow-up doctor appointments.

Emergency care for moderate to severe TBIs focuses on making sure the person has an adequate oxygen and blood supply, maintaining blood pressure, and preventing any further injury to the head or neck.

People with severe injuries may also have other injuries that need to be addressed. Additional treatments in the emergency room or intensive care unit of a hospital will focus on minimizing secondary damage due to inflammation, bleeding, or reduced oxygen supply to the brain.

Medications that limit secondary damage to the brain immediately after an injury may include:

  • diuretics. These drugs reduce the amount of fluid in tissues and increase urine output. Diuretics, given intravenously to people with traumatic brain injury, help reduce pressure inside the brain.
  • anti-seizure drugs. People who have had a moderate to severe TBI are at risk of having seizures during the first week after their injury. An anti-seizure drug may be given during the first week to avoid any additional brain damage that might be caused by a seizure. Additional anti-seizure treatments are used only if seizures occur.
  • coma-inducing drugs. Doctors sometimes use drugs to put people into temporary comas because a comatose brain needs less oxygen to function. This is especially helpful if blood vessels, compressed by increased pressure in the brain, are unable to deliver the usual amount of nutrients and oxygen to brain cells.

Emergency surgery may be needed to minimize additional damage to brain tissues. Surgery may be used to remove clotted blood (hematomas), repair skull fractures, or relieve pressure inside the skull.

Most people who have had a significant brain injury will require rehabilitation. They may need to relearn basic skills, such as walking or talking. The goal is to improve their abilities to perform daily activities.