Traumatic Brain Injury

sec_arr Appendix A: Overview and Case Definitions

Appendix A: Overview and Case Definitions

Traumatic brain injury (TBI) has been classified since the 1980s using the Glasgow Coma Score (GCS).13,14 As the name and objective physical findings imply, the initial GCS was proposed to standardize assessment of the comatose patient, not patients with transient or brief loss of conscious. Despite this and several other limitations, GCS is used in the United States to clinically classify head injury into 3 categories: 1) mild, 13-15; 2) moderate, 9-12; and 3) severe, 3-8. In some epidemiological and research settings, additional data is used to determine TBI severity (see Table A-1). It is important to identify and understand the diagnostic criteria used to define the severity of the injury in order to interpret the TBI literature.15 This is easier said than done, as several clinical specialties have assumed ownership of patients with TBI resulting in conflicting case definitions.

Table A-1. Traumatic Brain Injury Definitions16

TBI Severity

Structural Imaging

Loss of Consciousness

Post-traumatic Amnesia

Glasgow Coma Scale

Abbreviated Injury Score



<30 minutes

0-1 day





30 minutes to 24 hours

1 to 7 days





>24 hours

>7 days



Based on hospital data, the U.S. Centers for Disease Control and Prevention (CDC) estimates that 55% of all TBIs presenting to the emergency department occur in the working-age population (age 15-64), with 50% attributed to motor vehicle collision and falls. Of those, 85% are treated and released. Given today’s standard of care, patients with a moderate or severe TBI should be admitted to an acute care hospital for initial management. Therefore, a reasonable assumption is that 15% of TBIs in the working-age population are moderate or severe injuries.18

The research on mild traumatic brain injury (including concussion) is limited due to the various mechanism of injury, limitations of objective testing, and non-specific clinical symptoms. The peer-reviewed literature contains numerous articles on cohorts of college and professional athletes participating in numerous, varied sports activities after head injuries.5-9 This demonstrates that, in many cases, the LEO who has recovered from a concussion or traumatic brain injury will be able to perform his/her essential job functions in the same fashion that an athlete returns to practice and competition. In both cases, the athlete and the LEO have been cleared by their primary provider to return to the activity in question, presumably based on objective physical findings, post-injury rehabilitation timing and pathways, and the individual’s desire to return to that activity. Therefore, there should be minimal differences in assessing the ability to return to a field sport for an athlete and return to duty for the LEO.

Despite the wealth of literature on sport-related concussion (SRC), there are important limitations to consider when using SRC research to inform on the LEO’s ability to return to unrestricted duty, including:

  • SRC research relies on pre- and post-injury assessment which allows researchers to compare current subjective symptoms and objective findings against the individual’s baseline. This data is not available in most post-injury care settings, thus determining return to baseline function for non-sports related concussions (nSRC) relies heavily on the patient’s self-reported symptoms and return-to-baseline.
  • Return-to-sport typically has athletes return to modified practice and training activities under the supervision of coaches and trainers. Well-defined training activities and expert observers are typically not available in most agencies.
  • SRC research is heavily skewed towards adolescents and young adults, particularly male football players. Their recovery timeline may not be the same as the older population, particularly older patients with pre-existing or concomitant injuries.
  • SRC research does not account for other unique mechanisms of traumatic brain injury, including diffuse axonal injury, high-velocity motor vehicle accidents, penetrating head trauma and injuries associated with substance abuse.

Patients who have been admitted to an acute care hospital as a result of their TBI should be evaluated as if they have had a moderate or severe TBI regardless of their self-report diagnosis. Admission or transfer for observation and/or treatment for TBI injury to an acute care hospital is driven by the presence of specific symptoms (i.e., nausea, vomiting, dizziness, prolonged loss of consciousness, pre- and post-traumatic amnesia) and/or findings on imaging suggesting diffuse axonal injury, coup/contra-coup injuries, hemorrhage, and skull fractures. (Note: Imaging can be used to add diagnostic and prognostic information but is not used as part of the case definition for TBI with the exception of penetrating head trauma).


Traumatic brain injury – A disruption in the normal function of the brain that can be caused by a bump, blow, or jolt to the head. At least one of the following findings should be present after the initial event:

  • A period of altered consciousness
  • Any period of loss of consciousness
  • Any loss of memory for events immediately before (pre- or retrograde amnesia) of after the injury (post-traumatic amnesia)
  • Neurologic deficits such as muscle weakness, loss of balance and coordination, disruption of vision (including nausea and dizziness associated with eye movements), change in speech and language, or sensory loss.
  • Alteration in mental state at the time of injury such as confusion, disorientation, slowed thinking or difficulty with concentration.

Mild traumatic brain injury/concussion (all of the following should be present)

  • Loss of consciousness <30 minutes and
  • Post-traumatic amnesia lasting <24 hours and
  • Best available GCS in 24 hours between 13-15

Moderate traumatic brain injury (any of the following should be present)

  • Loss of consciousness >30 minutes but less than 24 hours or
  • Post-traumatic amnesia lasting >24 hours up to 1 week or
  • Best available GCS in 24 hours between 9-12

Severe traumatic brain injury (any of the following should be present)

  • Loss of consciousness >24 hours or
  • Post-traumatic amnesia lasting >7 days or
  • Best available GCS in 24 hours between 3-8

Other Terminology

Blunt traumatic brain injury – a concussive mechanical force is imparted to the head through direct contact with a blunt object, an inert broad surface or a rapidly expanding fluid wave.19

Cervicogenic headache – headache caused by a disorder of the cervical spine and its component bony, disc and/or soft tissue elements, usually but not invariably accompanied by neck pain.

Diagnostic criteria:

  • Any headache fulfilling criterion C (see below)
  • Clinical and/or imaging evidence of a disorder or lesion within the cervical spine or soft tissues of the neck, known to be able to cause headache
  • Evidence of causation demonstrated by at least two of the following:
    • headache has developed in temporal relation to the onset of the cervical disorder or appearance of the lesion
    • headache has significantly improved or resolved in parallel with improvement in or resolution of the cervical disorder or lesion
    • cervical range of motion is reduced, and headache is made significantly worse by provocative maneuvers
    • headache is abolished following diagnostic blockade of a cervical structure or its nerve supply
  • Not better accounted for by another International Headache Society Classification ICHD-3 diagnosis20

Migraine Headache

Migraine without aura – a recurrent headache disorder manifesting in attacks lasting 4 to 72 hours. Typical characteristics of the headache are unilateral location, pulsating quality, moderate or severe intensity, aggravation by routine physical activity and association with nausea and/or photophobia and phonophobia.

Diagnostic criteria:

  • At least 5 attacks fulfilling criterion B-D
  • Headache attacks lasting 4-72 hours (untreated or unsuccessfully treated)
  • Headache has at least 2 of the following four characteristics:
    • unilateral location
    • pulsating quality
    • moderate or severe pain intensity
    • aggravation by or causing avoidance of routine physical activity (e.g., walking, climbing stairs)
  • During headache at least one of the following:
    • nausea and/or vomiting
    • photophobia and phonophobia
  • Not better accounted for by another International Headache Society Classification (ICHD-3) diagnosis20

Migraine with aura – Recurrent attacks, lasting minutes, of unilateral fully reversible visual, sensory or other central nervous system symptoms that usually develop gradually and are usually followed by headache and associated migraine symptoms.

Diagnostic criteria:

  • At least 2 attacks fulfilling criteria B and C
  • One or more of the following fully reversible aura symptoms:
    • visual
    • sensory
    • speech and/or language
    • motor
    • brainstem
    • retinal
  • At least 2 of the following 4 characteristics:
    • at least 1 aura symptom spreads gradually over ≥5 minutes, and/or 2 or more symptoms occur in succession
    • each individual aura symptom lasts 5-60 minutes
    • at least one aura symptom is unilateral
    • the aura is accompanied, or followed within 60 minutes, by headache
  • Not better accounted for by another International Headache Society Classification (ICHD-3) diagnosis20

Penetrating head injury – Missile and non-missile injuries to the head that expose the cranial vault to the external environment. Also called open head injuries. By definition, penetrating head injury involves penetration through the dura mater.19

Post-traumatic epilepsy – Post-traumatic epilepsy (PTE) is defined as recurring seizures occurring more than 7 days after traumatic brain injury.21

Vestibulo-ocular dysfunction (VOD) – Patients with more than 1 subjective complaint of intermittent blurred or double vision; visual disturbance; difficulty concentrating, focusing, or reading; dizziness; or motion sensitivity AND the presence of more than 1 objective physical examination findings: abnormal near-point convergence (NPC), abnormal extraocular movements or smooth pursuit, vertical saccades, or vestibule-ocular reflexes.22

In addition, refer to the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders. 5th ed., for the following definitions23:

  • Mild or Major Neurocognitive Disorder Due to Brain Injury (DSM-5)
  • Mild Neurocognitive Disorder (DSM-5)
  • Major Neurocognitive Disorder (DSM-5)