Traumatic Brain Injury

doctors review patient information

What is Traumatic Brain Injury (TBI)?

TBI is an injury to the head resulting from blunt or penetrating trauma. Depending on the type, severity, and location of the injury, the person’s symptoms may include:

  • Loss of consciousness/coma
  • Sleep disturbances
  • Confusion and disorientation
  • Dizziness/loss of balance
  • Memory loss/amnesia
  • Irritability/emotional changes
  • Fatigue
  • Headaches
  • Depression or anxiety
  • Visual problems
  • Seizures
  • Poor attention/concentration
  • Nausea/Vomiting

TBI is often described as mild, moderate or severe. A Glasgow Coma Score (GCS) is a coma score that is used to assess a patient’s level of consciousness. The GCS has three categories that are scored based on a patient’s responsiveness. The categories consist of the patient’s ability to:

  • Open his or her eyes
  • Respond appropriately to orientation questions like, “what is your name?” and “what is the date today?”
  • Follow commands like holding up two fingers or responding to painful stimulation

A number is assigned to each category based on a patient’s performance and the scores are added together to get the total GCS score. The scores range from 3 to 15 and help determine if a patient has a mild, moderate or severe brain injury.

Click to expand a topic and learn more about the different types of TBI:

Mild TBI describes patients with normal or only a little bleeding seen on brain imaging. These patients sometimes lose consciousness for a short period of time after injury and may not remember details of the event. Mild TBI is sometimes called concussion and includes those with a GCS of 13-15.

Learn more about the treatments for mild TBI.

Moderate TBI describes patients with normal or abnormal brain imaging who experience a longer time period of loss of consciousness and amnesia.  Patients with moderate TBI often have prolonged confusion and sleepiness. Moderate TBI patients score from 9-12 on the GCS score.

Severe Traumatic Brain Injury

Severe TBI describes patients that usually have abnormal brain imaging and are often in a prolonged period of unconsciousness (coma).  These patients are treated in the neuroscience  intensive care unit (NSICU). Severe TBI is a GCS score below 9.

Patients with a severe TBI often have multiple areas of primary brain injury and are at increased risk of secondary injury. Secondary injury is an injury that occurs as a result of the body’s response to the primary injury. The inflammatory response of a brain injury causes extra fluid to collect in the brain in an attempt to heal the injury. In other areas of the body, swelling (edema) is a good response, but it can be dangerous in the brain where space is limited by the skull. The swelling causes injury to parts of the brain that were not initially injured, resulting in “secondary brain injury.”

Learn more about our treatments for severe TBI.

Learn more about TBI

The initial injury is known as the primary injury. Primary injuries can affect the entire brain (diffuse injuries) or a specific section (focal injuries).

Types of diffuse injuries include:

Concussions – mild head injuries that can cause brief loss of consciousness without brain tissue injury.

Traumatic subarachnoid hemorrhage—caused from bleeding on the surface of the brain.

Diffuse axonal injury (DAI) – commonly referred to as shear injury. This is an injury that occurs when the brain quickly moves back and forth inside the skull damaging the cells that carry information throughout the brain. This disrupts how the brain normally communicates information and can result in changes in a patient’s consciousness.

Types of focal injuries include:

Cerebral contusion – a bruise on the brain tissue.

Subdural hematoma (SDH) – bleeding that occurs under the dura, or layer of tissue that surrounds the brain. Tearing of veins or vessels that deliver the blood back to the heart is often the cause this type of bleeding.

An epidural hematoma (EDH) – a blood clot that forms on top of the dura, below the skull. Arteries that supply blood from the heart most commonly cause this type of bleed. Because the blood within the arteries travels at a high pressure this bleed can grow quickly, resulting in a rapid decrease in a patient’s consciousness.

Intracranial hematoma (ICH) – is bleeding within the brain tissue.

Intraventricular hemorrhage (IVH) – is blood within the fluid filled spaces inside the brain.

picture illustrates impact injuries


Although we describe these as individual injuries, it is rare for a patient to suffer only one type of injury. It is more common for a patient to have a combination of injuries, all of which may have different levels of severity and can be in different parts of the brain. Parts of the brain have different functions, and someone that suffers a TBI may have many symptoms because of the variety of brain regions injured.

Explore the UC Neurotrauma Center