Traumatic brain injury (TBI), also called acquired brain injury or head injury, occurs when a sudden trauma causes damage to the brain that results in a change in mental status, the duration of which depends on the severity of the injury.


  • Impact to the head
  • Falls
  • Collisions involving cars, motorcycles and bicycles
  • Assaults – gunshot wounds, child abuse
  • Entry of an object into the skull that enters brain tissue (e.g. bullet, piece of bone)
  • Forceful motion of the head


  • The risk of traumatic brain injury is highest in young men ages 15 to 24.
  • The head injury is often missed at the time of the initial injury. 
  • 15% of people with mild TBI have symptoms that last one year or more. Moderate to severe TBIs can result in permanent neurobiological damage that can produce lifelong deficits to varying degrees. 
  • Disabilities depend upon the severity of the injury, the location of the injury, and the age and general health of the individual. They can include problems with the senses, cognition, communication, and behavior. Severe head injuries may result in coma or a persistent vegetative state. 


Depending on the extent of damage to the brain, the symptoms of TBI can be mild to severe. Certain symptoms reflect injury to specific areas of the brain: damage to the frontal lobes will cause loss of higher cognitive functions, such as loss of inhibitions leading to inappropriate social behavior; damage to the cerebellum will cause loss of coordination and balance; damage to the brainstem could affect breathing, heart rate and arousal.

Mild symptoms may be subtle and not perceptible at the time of the injury.

  • No loss of consciousness or duration of loss of consciousness of less than 30 minutes
  • Swelling, intracranial pressure
  • Amnesia for events immediately before and after the injury
  • Headache, lightheadedness
  • Confusion, getting lost 
  • Visual disturbances, sensitivity to light, blurred vision, eyes that tire easily
  • Ringing in the ears, sensitivity to sounds
  • Nausea, bad taste in the mouth
  • Fatigue, lethargy, lack of motivation 
  • A change in sleep patterns
  • Irritability, mood changes 
  • Depression 
  • Memory or concentration problems

Moderate or severe TBI symptoms may be the same as those for mild TBI, but the symptoms may be harsher. With a moderate brain injury, the patient loses consciousness up to 6 hours: with a severe brain injury, loss of consciousness is greater than 6 hours.

  • Persistent headache 
  • Repeated vomiting or nausea 
  • Convulsions or seizures 
  • An inability to awaken from sleep
  • Dilation of one or both pupils of the eyes 
  • Speech problems including slurred speech, difficulty understanding the spoken word and difficulty speaking 
  • Reading and writing problems 
  • Weakness or numbness in the extremities 
  • Loss of stamina and coordination 
  • Dizziness 
  • Lack of motivation 
  • Increased confusion, restlessness, agitation or combativeness


If the head injury is mild or moderate, and the patient has other life threatening injuries, the head injury may be missed while other injuries are being treated. Only when the patient resumes normal activities and begins to have problems with social situations or easy tasks, does one suspect TBI. Diagnosis would then include:

  • A detailed neurological examination The neurological assessment may include a standardized exam called the Glasgow Coma Scale. This 15-point test helps assess the severity of a brain injury by checking your ability to follow directions, to blink your eyes or to move extremities. The coherence of your speech also provides important clues. Your abilities are scored numerically. Higher scores mean milder injuries. 
  • Brain imaging with CAT scan or MRI
  • Cognitive evaluation by a neuropsychologist with formal neuropsychological testing 
  • Evaluations by physical, occupational 


  • Medical attention as soon as possible which includes stabilizing an individual with TBI and preventing further injury. Primary concerns include insuring proper oxygen supply to the brain and the rest of the body, maintaining adequate blood flow, and controlling blood pressure.
  • Medication to help reduce brain swelling or to control seizures
  • Surgery to remove or repair blood clots or bruised brain tissue or to relieve pressure inside the brain 
  • Rehabilitation: individually tailored treatment programs in the areas of physical therapy, occupational therapy, speech/language therapy, physiatry (physical medicine), psychology/psychiatry, and social support. 


  • Wear a seat belt. 
  • Wear a helmet for appropriate sporting activities including skiing, cycling, football, ice-hockey, horseback riding, batting in baseball. 
  • Avoid falls by removing tripping hazards in the home, using mats under area rugs to make the rugs non-slip and using non slip mats in bathtubs and showers.
  • Use safety gates at tops and bottoms of stairs to protect young children. 
  • Store unloaded firearms in a locked cabinet with bullets locked elsewhere.
  • Always drive sober. 

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Content generated and provided by Joshua B. Bederson, MD, Professor and Chairman of the Department of Neurosurgery at The Mount Sinai Health System. Some of the information contained in this article was adapted from the National Institutes of Health. Last reviewed October 2011 by the Department of Neurosurgery at The Mount Sinai Health System.