What is a Traumatic Brain Injury?

Traumatic brain injury (TBI) is any injury to the brain caused by trauma to the head. If there is trauma to the brain but the skull is not broken, the TBI is known as a closed head injury. This could occur, for example, if a person in an automobile accident hits his head on the steering wheel but doesn’t have a skull fracture. If an object such as a bullet penetrates the skull and injures the brain, the TBI is known as a penetrating head injury.

TBI is considered a "sterile" injury .

What Are the Signs and Symptoms of TBI?

Mild TBI

Symptoms of mild TBI include headache, confusion, lightheadedness, dizziness, blurred vision or tired eyes, ringing in the ears, bad taste in the mouth, fatigue, a change in sleep patterns, mood changes, and trouble with memory, concentration, attention, or thinking. The injury may or may not result in a brief period of unconsciousness. Most(over 70%) brain injury cases are classified as mild.

Moderate or Severe TBI

Symptoms of mild to moderate TBI can include a headache that gets worse or does not go away, repeated vomiting or nausea, convulsions or seizures, inability to awaken from sleep, dilation of one or both pupils of the eyes, slurred speech, weakness or numbness in the arms or legs, loss of coordination, increased confusion, restlessness, or agitation.

Symptoms in Children

While children with a TBI may have the same symptoms as adults, there are some symptoms unique to young children, including persistent crying and refusing to nurse or eat.

What Are the Causes of TBI?

Half of all TBIs are due to accidents involving automobiles, motorcycles, bicycles, and pedestrians. Motor vehicle accidents are the major cause of TBI in people under age 75. For those 75 and older, falls cause the majority of TBIs. Approximately twenty percent of TBIs are due to violence, such as gunshots and child abuse. About three percent are due to sports injuries. Alcohol use is associated with half of all TBIs. Learn ways to prevent traumatic brain injuries.

What Are the Different Types of TBI?


A concussion is the most minor and common type of TBI. Doctors define a concussion as a short loss of consciousness following a head injury, but many people now refer to any minor injury to the head or brain as a concussion.

The signs of a person with a concussion are:

  1. Blank stare-the lack of facial expression.
  2. Delayed verbal response-the inability to respond questions or other stimuli quickly, such as verbal or written instructions.
  3. Unable to focus or concentrate-the inability to concentrate or pay attention for periods of time. The person’s attention is shifting from one thing to another.
  4. Disorientation-the lack of coordination when walking or doing other activities, not cognizant of time, days or places.
  5. Slurred speech-displaying the inability to pronounce words and at times slurring one’s speech. The person may become easily distraught, agitated and may start to withdrawal from friends or family members.
  6. Memory discrepancy-the individual’s memory is affected to the point that short-term or even long-term memory loss may become a temporary affliction or permanent. The loss of consciousness due for any period of time may also result in temporary too permanent memory loss.

In certain cases cortical neurological deficiencies such as global amnesia or cortical blindness may occur.

Skull Fracture

Skull fractures occur when the skull cracks or breaks. A depressed skull fracture occurs when pieces of broken skull press into the tissue of the brain. A penetrating skull fracture occurs when something pierces the skull and injures the brain.


A contusion is bruising of the brain. The bruised area swells and bleeds like bruises we can see in the skin or muscle. Contusions often occur with skull fractures. However, even when the outside of the skull is struck by an object and does not break, the impact may be hard enough to cause the brain to bounce off the inside of the skull and suffer a contusion. Contusions can also happen when the head doesn’t strike anything. For example, contusions often occur in car accidents after high-speed stops or collisions. In these cases the abrupt forward movement of the head with a sudden stop followed by the head rapidly recoiling backwards causes the brain to bounce off the skull (often it bounces off more than one side of the skull). Shaking a baby violently can cause the same kind of injury. These type of injuries are often called coup and contrecoup injuries.


A hematoma is a collection of blood inside the body. The brain is surrounded by a tough outer sheath called the dura. Bleeding in the area between the dura and the skull is called an epidural (above the dura) hematoma. There is an inner sheath that also surrounds the brain that is called the arachnoid membrane. Bleeding between the outer sheath (the dura) and the inner membrane (the arachnoid) is called a subdural (beneath the dura) hematoma. Bleeding inside the brain itself is called an intracerebral hematoma traumatic brain injuries are diagnosed and treated.