PDF version: Traumatic Brain Injury (pdf, 631 kb)
A traumatic brain injury (TBI) can be caused by a forceful bump, blow, or jolt to the head or body, or from an object that pierces the skull and enters the brain. Not all blows or jolts to the head result in a TBI.
Some types of TBI can cause temporary or short-term problems with normal brain function, including problems with how the person thinks, understands, moves, communicates, and acts. More serious TBI can lead to severe and permanent disability, and even death.
Some injuries are considered primary, meaning the damage is immediate. Other outcomes of TBI can be secondary, meaning they can occur gradually over the course of hours, days, or appear weeks later. These secondary brain injuries are the result of reactive processes that occur after the initial head trauma. There are two broad types of head injuries: penetrating and non-penetrating.
Some accidents such as explosions, natural disasters, or other extreme events can cause both penetrating and non- penetrating TBI in the same person.
Seek immediate medical attention if you experience any of the following physical, cognitive/behavioral, or sensory symptoms, especially within the first 24 hours after a TBI:
Headache, dizziness, confusion, and fatigue tend to start immediately after an injury, but resolve over time. Emotional symptoms such as frustration and irritability tend to develop during recovery.
Children might be unable to let others know that they feel different following a blow to the head. A child with a TBI may display the following signs or symptoms:
A TBI can cause problems with consciousness, awareness, alertness, and responsiveness. Generally, there are four abnormal states that can result from a severe TBI:
TBI-related damage can be confined to one area of the brain, known as a focal injury, or it can occur over a more widespread area, known as a diffuse injury. The type of injury also affects how the brain is damaged.
Primary effects on the brain include various types of bleeding and tearing forces that injure nerve fibers and cause inflammation, metabolic changes, and brain swelling.
Secondary damage can include:
Other secondary damage can be caused by infections to the brain, low blood pressure or oxygen flow as a result of the injury, hydrocephalus (a buildup of fluid in the brain that can increase pressure on brain tissue), and seizures.
Falls. According to data from the Centers for Disease Control and Prevention (CDC), falls are the most common cause of TBIs and occur most frequently among the youngest and oldest age groups. From 2006 to 2010 alone, falls caused more than half (55 percent) of TBIs among children aged 14 and younger. Among Americans age 65 and older, falls accounted for more than two-thirds (81 percent) of all reported TBIs.
Blunt trauma accidents. Accidents that involve being struck by or against an object, particularly sports-related injuries, are a major cause of TBI. Anywhere from 1.6 million to 3.8 million sports- and recreation-related TBIs are estimated to occur in the United States annually.
Vehicle-related injuries. Pedestrian-involved accidents, as well as accidents involving motor vehicles and bicycles, are the third most common cause of TBI. In young adults aged 15 to 24 years, motor vehicle accidents are the most likely cause of TBI.
Assaults/violence. Assaults include abuse related TBIs, such as head injuries that result from domestic violence or shaken baby syndrome, and gunshot wounds to the head. TBI-related deaths in children age 4 and younger are most likely the result of assault.
Explosions/blasts. TBIs caused by blast trauma from roadside bombs became a common injury to service members in recent military conflicts. The majority of these TBIs were classified as mild head injuries.
Adults age 65 and older are at greatest risk for being hospitalized and dying from a TBI, most likely from a fall. In every age group, serious TBI rates are higher for men than for women. Men are more likely to be hospitalized and are nearly three times more likely to die from a TBI than women.
Additional information about TBI and its causes can be found on the U.S. Centers for Disease Control and Prevention TBI website: http://www.cdc.gov/TraumaticBrainInjury/.
All TBIs require immediate assessment by a professional who has experience evaluating head injuries. A neurological exam will judge motor and sensory skills and test hearing and speech, coordination and balance, mental status, and changes in mood or behavior, among other abilities. Screening tools for coaches and athletic trainers can identify the most concerning concussions for medical evaluation.
Initial assessments may rely on standardized instruments such as the Acute Concussion Evaluation (ACE) form from the Centers for Disease Control and Prevention or the Sport Concussion Assessment Tool 2, which provide a systematic way to assess a person who has suffered a mild TBI. Reviewers collect information about the characteristics of the injury, the presence of amnesia (loss of memory) and/or seizures, as well as the presence of physical, cognitive, emotional, and sleep-related symptoms. The ACE is also used to track symptom recovery over time. It also takes into account risk factors (including concussion, headache, and psychiatric history) that can impact how long it takes to recover from a TBI.
Diagnostic imaging. When necessary, medical providers will use brain scans to evaluate the extent of the primary brain injuries and determine if surgery will be needed to help repair any damage to the brain. The need for imaging is based on a physical examination by a doctor and a person’s symptoms.
Neuropsychological tests to gauge brain functioning are often used in conjunction with imaging in people who have suffered mild TBI. Such tests involve performing specific cognitive tasks that help assess memory, concentration, information processing, executive functioning, reaction time, and problem solving. The Glasgow Coma Scale is the most widely used tool for assessing the level of consciousness after TBI. The standardized 15-point test measures a person’s ability to open his or her eyes and respond to spoken questions or physical prompts for movement. A total score of 3-8 indicates a severe head injury; 9-12 indicates moderate injury; and 13-15 is classified as mild injury. (For more information about the scale, see http://glasgowcomascale.org/).
Many athletic organizations recommend establishing a baseline picture of an athlete’s brain function at the beginning of each season, ideally before any head injuries have occurred. Baseline testing should begin as soon as a child begins a competitive sport. Brain function tests yield information about an individual’s memory, attention, and ability to concentrate and solve problems. Brain function tests can be repeated at regular intervals (every 1 to 2 years) and also after a suspected concussion. The results may help health care providers identify any effects from an injury and allow them to make more informed decisions about whether a person is ready to return to their normal activities.
Many factors, including the size, severity, and location of the brain injury, influence how a TBI is treated and how quickly a person might recover. One of the critical elements to a person’s prognosis is the severity of the injury. Although brain injury often occurs at the moment of head impact, much of the damage related to severe TBI develops from secondary injuries which happen days or weeks after the initial trauma. For this reason, people who receive immediate medical attention at a certified trauma center tend to have the best health outcomes.
Some people with mild TBI such as concussion may not require treatment other than rest and over-the-counter pain relievers. Treatment should focus on symptom relief and “brain rest.” Monitoring by a healthcare practitioner is important to note any worsening of symptoms or new ones.
Children and teens who have a sports-related concussion should stop playing immediately and return to play only after being approved by a concussion injury specialist.
Preventing future concussions is critical. While most people recover fully from a first concussion within a few weeks, the rate of recovery from a second or third concussion is generally slower.
Even after symptoms resolve entirely, people should return to their daily activities gradually once they are given permission by a doctor. There is no clear timeline for a safe return to normal activities although there are guidelines such as those from the American Academy of Neurology and the American Medical Society for Sports Medicine to help determine when athletes can return to practice or competition. Further research is needed to better understand the effects of mild TBI on the brain and to determine when it is safe to resume normal activities.
People with a mild TBI should:Make an appointment for a follow-up visit with their healthcare provider to confirm the progress of their recovery.
These symptoms may be related even if they occurred several weeks after the injury.
Medications to treat some of the symptoms of TBI may include:
Immediate treatment for someone who has suffered a severe TBI focuses on preventing death; stabilizing the person’s spinal cord, heart, lung, and other vital organ functions; ensuring proper oxygen delivery and breathing; controlling blood pressure; and preventing further brain damage. Emergency care staff also will monitor the flow of blood to the brain, brain temperature, pressure inside the skull, and the brain’s oxygen supply.
Surgery may be needed to for emergency medical care and to treat secondary damage, including:
In-hospital strategies for managing people with severe TBI aim to prevent conditions including:
People with TBIs may need nutritional supplements to minimize the effects that vitamin, mineral, and other dietary deficiencies may cause over time. Some individuals may even require tube feeding to maintain the proper balance of nutrients.
After the acute care period of in-hospital treatment, people with severe TBI are often transferred to a rehabilitation center where a multidisciplinary team of health care providers help with recovery.
The rehabilitation team includes neurologists, nurses, psychologists, nutritionists, as well as physical, occupational, vocational, speech, and respiratory therapists.
Therapy is aimed at improving the person’s ability to handle activities of daily living and to address cognitive, physical, occupational, and emotional difficulties. Treatment may be needed only short-term or throughout a person’s life. Some therapy is provided through outpatient services.
Cognitive rehabilitation therapy (CRT) is a strategy aimed at helping individuals regain their normal brain function through an individualized training program. Using this strategy, people may also learn compensatory strategies for coping with persistent deficiencies involving memory, problem solving, and the thinking skills to get things done. CRT programs tend to be highly individualized and their success varies. A 2011 Institute of Medicine report concluded that cognitive rehabilitation interventions need to be developed and assessed more thoroughly.
Genetics may play a role in how quickly and completely a person recovers from a TBI. For example, researchers have found that apolipoprotein E ε4 (ApoE4) — a genetic variant associated with higher risks for Alzheimer’s disease — is associated with worse health outcomes following a TBI. Much work remains to be done to understand how genetic factors, as well as how specific types of head injuries, affect recovery. This research may lead to new treatment strategies and improved outcomes for people with TBI.
Studies suggest that age and the number of head injuries a person has suffered over his or her lifetime are two critical factors that impact recovery. For example, TBI-related brain swelling in children can be very different from the same condition in adults, even when the primary injuries are similar. Brain swelling in newborns, young infants, and teenagers often occurs much more quickly than it does in older individuals. Evidence from very limited CTE studies suggest that younger people (ages 20 to 40) tend to have behavioral and mood changes associated with CTE, while those who are older (ages 50+) have more cognitive difficulties.
Compared with younger adults with the same TBI severity, older adults are likely to have less complete recovery. Older people also have more medical issues and are often taking multiple medications that may complicate treatment (e.g., blood-thinning agents when there is a risk of bleeding into the head). Further research is needed to determine if and how treatment strategies may need to be adjusted based on a person’s age.
Researchers are continuing to look for additional factors that may help predict a person’s course of recovery.
The best treatment for TBI is prevention. Unlike most neurological disorders, head injuries can be prevented. According to the CDC, doing the following can help prevent TBIs:
The mission of the National Institute on Neurological Disorders and Stroke (NINDS) is to seek fundamental knowledge about the brain and nervous system and use that knowledge to reduce the burden of neurological disease. The NINDS is a component of the National Institutes of Health (NIH), the leading supporter of biomedical research in the world.
NINDS supports research across the full range of TBI severity, in animal models and people, from children to adults. Projects focus on the mechanisms that result in immediate and delayed damage to the brain, on the processes that underlie recovery, and developing better diagnostic tools and more effective treatments.
Among NINDS research efforts:
In addition to NINDS, other NIH Institutes fund research on TBI. Research projects on TBI and other disorders can be found using NIH RePORTER (http://projectreporter.nih.gov), a searchable database of current and past research projects supported by NIH and other federal agencies. RePORTER also includes links to publications from these projects and other resources.
Despite recent progress in understanding what happens in the brain following TBI, more than 30 large clinical trials have failed to identify specific treatments that make a dependable and measurable difference in people with TBI. A key challenge facing doctors and scientists is the fact that each person with a TBI has a unique set of circumstances based on such multiple variables as the location and severity of the injury, the person’s age and overall heath, and the time between the injury and the initiation of treatment. These factors, along with differences in care across treatment centers, highlight the importance of coordinating research efforts so that the results of potential new treatments can be confidently measured.
NINDS co-leads the Strategies to Innovate EmeRgENcy Care Clinical Trials (SIREN) network, with projects that include TBI trials — one of which is looking at brain tissue oxygen monitoring to improve neurologic outcome in the most severely injured people with TBI.
Harnessing the efforts of the many physicians and scientists working on developing better treatments for TBI requires everyone to collect the same types of information from people, including details about injuries and treatment results. To lay the groundwork for these studies, NINDS started the Common Data Elements project. This effort brings the research community together to develop data collection standards.
NINDS — in coordination with the European Commission (that also supports brain health) — brings together studies through the International Initiative for TBI research (InTBIR) to collect data and encourage new collaborations to improve diagnosis and evaluate which types of care are associated with the best outcomes in children and adults.
NIH and the Department of Defense together lead the Federal Interagency TBI Research (FITBIR) database, which includes both new observational studies and other studies, such as the Child Health After Injury Study.
NIH investigators along with the Food and Drug Administration, are active collaborators in the Department of Defense-led TBI Endpoints Initiative to advance diagnosis and treatment of TBI.
NINDS also works with Department of Defense and the Departments of Health and Human Services, Veterans Affairs, and Education to coordinate TBI research for military members. This National Research Action Plan (NRAP) aims to improve prevention, diagnosis, and treatment of TBI and other mental health conditions such as PTSD that affect veterans and their families. The findings resulting from NRAP will be rapidly translated into new effective prevention strategies and clinical innovations, as well as identify biomarkers to detect these disorders early and accurately.
If you or someone you know has been diagnosed with a TBI, enrolling in a clinical trial or brain bank are the best ways to support research toward new and better treatment options.
Clinical trials are research studies that involve people. Studies involving individuals with TBI and healthy individuals offer researchers the opportunity to greatly increase our knowledge of TBI and find better ways to safely detect, treat, and ultimately prevent TBI. By participating in a clinical study, healthy individuals and those with TBI can greatly benefit the lives of those living with this disorder. Talk with your doctor about clinical studies and help to make the difference in the quality of life for all people with TBI. Trials take place at medical centers across the United States and elsewhere. For information about NINDS-funded studies on TBI, see www.clinicaltrials.gov and search for “TBI AND NINDS.” For additional studies on TBI and information about participating in clinical studies, visit the “NIH Clinical Trials and You” website. Always talk with your health care provider before enrolling in a clinical trial.
People with a TBI also can support TBI research by designating the donation of brain tissue before they die. The study of human brain tissue is essential to increasing the understanding of how the nervous system functions.
The NIH NeuroBioBank is an effort by the National Institutes of Health to coordinate the network of brain banks it supports in the United States to advance research through the collection and distribution of post-mortem brain tissue. Stakeholder groups include brain and tissue repositories, researchers, NIH program staff, information technology experts, disease advocacy groups, and most importantly individuals seeking information about opportunities to donate. It ensures protection of the privacy and wishes of donors. Creating a network of these centers makes it more likely that precious tissue can be made available to the greatest number of scientists.
For more information on neurological disorders or research programs funded by the National Institute of Neurological Disorders and Stroke, contact the Institute's Brain Resources and Information Network (BRAIN) at:
P.O. Box 5801
Bethesda, MD 20824
Information also is available from the following organizations:
Brain Injury Association of America
1608 Spring Hill Road, Suite 110
Vienna, VA 22182
Brain Injury Resource Center
P.O. Box 84151
Seattle, WA 98124
Brain Trauma Foundation
1 Broadway, 6th Floor
New York, NY 10004-1007
Uniformed Services University of the Health Sciences (USUHS)
Center for Neuroscience and Regenerative Medicine (CNRM)
NIH-USUHS TBI Center
4301 Jones Bridge Road
Bethesda, MD 20814-4799
Defense and Veterans Brain Injury Center
7700 Arlington Blvd. Suite 5101
Falls Church, VA 22041
U.S. Centers for Disease Control and Prevention
Heads Up to Concussion
National Center for Injury Prevention and Control (NCIPC)
Division of Unintentional Injury Prevention
1600 Clifton Road
Atlanta, GA 30329-4027
National Rehabilitation Information Center
8400 Corporate Drive, Suite 500
Landover, MD 20785
National Injury Prevention Foundation
1801 N. Mill Street, Suite F
Naperville, IL 60563
National Library of Medicine
National Institutes of Health
8600 Rockville Pike
Bethesda, MD 20894
"Traumatic Brain Injury Hope Through Research", NINDS, Publication date February 2020.
NIH Publication No. 20-NS-158
Publicaciones en Español
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.