Traumatic Brain Injury

Matthew E. Peters, M.D., Vani Rao, M.D.


  • Traumatic brain injury (TBI) is most simply defined as damage to the brain from trauma to the head from a source outside of the brain.
  • The Centers for Disease Control and Prevention (CDC) defines the cause of TBI as a bump, blow, or jolt to the head or a penetrating head injury that disrupts the normal function of the brain (
    • It is important to remember that not all blows or jolts to the head result in a TBI.
  • Severity of TBI is rated at the time of injury/initial assessment as mild, moderate, or severe according to Glasgow Coma Scale (GSW), duration of loss of consciousness (LOC), and/or duration of posttraumatic amnesia (PTA) (see Table Severity of TBI)[1].
    • Importantly, the severity rating of the TBI itself does not necessarily correspond to the severity of the resulting psychiatric phenomena.
Severity of TBI

Injury Characteristic

Mild TBI

Moderate TBI

Severe TBI

Loss of consciousness (LOC)

< 30 minutes

30 minutes - 24 hours

>24 hours

Posttraumatic amnesia (PTA)

< 24 hours

24 hours - 7 days

>7 days

Disorientation and confusion at initial assessment

(Gasgow Coma Scale Score)

13-15 (not below

13 at 30 minutes)



  • Psychiatric disorders that may result from TBI are wide-ranging and include mood disturbances, psychosis, cognitive disturbances, and behavioral disturbances.
    • Certain symptoms such as sleep disturbances, fatigue, apathy, and pathological laughter / crying may occur in isolation rather than as part of a psychiatric syndrome.
  • Although as described below TBI can have a number of psychiatric sequalae, the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) only includes cognitive impairment due to TBI, which is classified in the neurocognitive disorders (NCDs) section[1].

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Last updated: March 1, 2017