How do health care providers diagnose traumatic brain injury (TBI)?

To diagnose TBI, health care providers may use one or more tests that assess a person's physical injuries, brain and nerve functioning, and level of consciousness. Some of these tests are described below.

Glasgow Coma Scale (GCS)

The GCS measures a person's functioning in three areas:

  • Ability to speak, such as whether the person speaks normally, speaks in a way that doesn't make sense, or doesn't speak at all
  • Ability to open eyes, including whether the person opens his or her eyes only when asked
  • Ability to move, ranging from moving one's arms easily to not moving even in response to painful stimulation

A health care provider rates a person's responses in these categories and calculates a total score. A score of 13 and higher indicates a mild TBI, 9 through 12 indicates a moderate TBI, and 8 or below indicates severe TBI.1 However, there may be no correlation between initial GCS score and the person's short- or long-term recovery or abilities.2

Measurements for Level of TBI

Health care providers sometimes rank the person's level of consciousness, memory loss, and GCS score.

A TBI is considered mild if:

  • The person was not unconscious or was unconscious for less than 30 minutes.
  • Memory loss lasted less than 24 hours.
  • The GCS was 13 to15.

NICHD-supported research has found, however, that diagnosis of mild TBI (concussion), in practice, uses inconsistent criteria and relies heavily on patients' self-reported symptoms.3

A TBI is considered moderate if:

  • The person was unconscious for more than 30 minutes and up to 24 hours.
  • Memory loss lasted anywhere from 24 hours to 7 days.
  • The GCS was 9 to 12.

A TBI is considered severe if:

  • The person was unconscious for more than 24 hours.
  • Memory loss lasted more than 7 days.
  • The GCS was 8 or lower.4

Speech and Language Tests

  • A speech-language pathologist completes a formal evaluation of speech and language skills, including an oral motor evaluation of the strength and coordination of the muscles that control speech, understanding and use of grammar and vocabulary, as well as reading and writing.5
    • Social communication skills are evaluated with formal tests and role-playing scenarios.
    • If a patient has problems with swallowing, the speech-language pathologist will make recommendations regarding management and treatment to ensure that the individual is able to swallow safely and receive adequate nutrition.

Cognition and Neuropsychological Tests

  • Cognition describes the processes of thinking, reasoning, problem solving, information processing, and memory.
    • Most patients with severe TBI suffer from cognitive disabilities, including the loss of many higher level mental skills.
  • Neuropsychological assessments are often used to obtain information about cognitive capabilities.
    • These tests are specialized task-oriented evaluations of human brain-behavior relationships, evaluating higher cognitive functioning as well as basic sensory-motor processes.6
    • Testing by a neuropsychologist can assess the individual's cognitive, language, behavioral, motor, and executive functions and provide information regarding the need for rehabilitative services.1
    • For this assessment, a neuropsychologist reviews the case history and hospital records of the patient, and interviews the patient and his/her family.
    • The neuropsychologist acquires information about the "person" the individual was before the injury, based on aspects like school performance, habits, and lifestyle, in order to detail which abilities remain unchanged as well as areas of the brain that are adversely affected by the injury and how the injury is expected to impact the individual's life.6

Imaging Tests

Health care providers may also use tests that take images of a person's brain. These include, but are not limited to:

  • Computerized tomography (CT). A CT (or "cat") scan takes X-rays from many angles to create a complete picture. It can quickly show bleeding in the brain, bruised brain tissue, and other damage.
  • Magnetic resonance imaging (MRI). MRI uses magnets and radio waves to produce more detailed images than CT scans. An MRI likely would not be used as part of an initial TBI assessment because it takes too long to complete. It may be used in follow-up examinations, though.6
  • Intracranial pressure (ICP) monitoring. Sometimes, swelling of the brain from a TBI can increase pressure inside the skull. The pressure can cause additional damage to the brain. A health care provider may insert a probe through the skull to monitor this swelling.2 In some cases, a shunt or drain is placed into the skull to relieve ICP.

Tests for Assessing TBI in Military Settings

A severe trauma may be obvious in a military situation, but a milder TBI may not be as easy to identify. The U.S. Department of Defense and Department of Veterans Affairs have therefore established procedures to assess quickly whether the person suffered:

  • A loss of consciousness
  • Memory problems
  • Neurologic symptoms, such as confusion or poor coordination

This assessment, combined with other measures, helps determine the type of care necessary, including evacuation for a higher level of treatment.7 Read more about TBI in the military External Web Site Policy and assessing mild TBI in combat and among veterans External Web Site Policy.


  1. National Institute of Neurological Disorders and Stroke. (2017). Traumatic brain injury: Hope through research. Retrieved April 9, 2018, from
  2. Brain Injury Association of America. About brain injury. Retrieved June 13, 2012, from External Web Site Policy
  3. Duhaime, A. C., Beckwith, J. G., Maerlender, A. C., McAllister, T. W., Crisco, J. J., Duma, S. M., Brolinson, P. G., Rowson, S., Flashman, L. A., Chu, J. J., & Greenwald, R. M. (2012). Spectrum of acute clinical characteristics of diagnosed concussions in college athletes wearing instrumented helmets: clinical article. Journal of Neurosurgery, 117, 1092–1099.
  4. Centers for Disease Control and Prevention. Glasgow Coma Scale. Atlanta, GA: U.S. Department of Health and Human Services. Retrieved on May 4, 2018, from (PDF - 74.5 KB) External Web Site Policy
  5. American Speech-Language-Hearing Association. Traumatic brain injury. Retrieved May 4, 2018, from External Web Site Policy
  6. Brain Injury Association of America. Diagnosing brain injury. Retrieved June 13, 2012, from External Web Site Policy
  7. Defense and Veterans Brain Injury Center. (2011). Concussion/mTBI screening. Retrieved June 13, 2012, from External Web Site Policy

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