Table 2

Key components for identifying a concussion—comparison of different definitions*

Organisation, year publishedDefinition of concussionDomains assessedKey featuresDefinition mTBI? Link concussion - TBI?Notes
Concussion in sports group,12 28–30
2002, 2005, 2009, 2013
‘A complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces’ that ‘may be caused by a direct blow to the head, face, neck or elsewhere in the body with an impulsive force transmitted to the head’.
Common features include:
  • Rapid onset of short-lived impairment of neurological function that resolves spontaneously

  • May result in neuropathological changes, but the acute clinical symptoms largely reflect a functional disturbance rather than a structural injury

  • Graded set of neurological syndromes that may or may not involve an LOC. Resolution of the clinical and cognitive features typically follows a sequential course. In some cases symptoms may be prolonged.

  • Typically associated with grossly normal structural neuroimaging studies.

  • Clinical symptoms (physical, cognitive, emotional)

  • Physical signs

  • Cognitive impairment

  • Neurobehavioural features

  • Sleep disturbances

Onset: rapid
Duration: short-lived
Mechanism of impairment: functional disturbance rather than structural injury
LOC: may or may not
Resolution: sequential
Neuroimaging: no abnormalities on standard structural neuroimaging
No (concussion is considered as subset of TBI)This definition also comments on typical neuroimaging features in concussion.
American Medical Society for Sports Medicine,31
2013
‘A concussion is defined as a traumatically induced transient disturbance of brain function and is caused by a complex pathophysiological process. Concussions have also been referred to as mild traumatic brain injuries (mTBI). While all concussions are mTBIs, not all mTBIs are concussions. Concussions are a subset of mTBIs, on the less-severe end of the brain injury spectrum and are generally self-limited in duration and resolution’.
  • Symptoms and signs (physical, cognitive, emotional, sleep)

Onset: not specified
Duration: transient, self-limited
Mechanism of impairment: functional disturbance
LOC: may or may not
Resolution: not specified
Neuroimaging: not specified
No (concussion is considered as subset of mTBI)
National Athletic Trainers' Association,33 34
2004, 2014
‘Trauma-induced alteration in mental status that may or may not involve loss of consciousness’
  • Not specified

Onset: not specified
Duration: not specified
Mechanism of impairment: not specified
LOC: may or may not
Resolution: not specified
Neuroimaging: not specified
No (concussion and mTBI are used interchangeably)
American Academy of Neurology,32 46
1997, 2013
‘Concussion is a trauma-induced alteration in mental status that may or may not involve loss of consciousness. Confusion and amnesia are the hallmarks of concussion. The confusional episode and amnesia may occur immediately after the blow to the head or several minutes later’.
  • Clinical symptoms (physical, cognitive, emotional)

  • Physical signs

  • Cognitive impairment

  • Sleep disturbances

Onset: immediate or within mins
Duration: not specified
Mechanism of impairment: not specified
LOC: may or may not
Resolution: not specified
Neuroimaging: not specified
No (concussion and mTBI are used interchangeably)1997 definition was used as the 2013 revision provided a shortened definition only.
Team Physician Consensus statements (AAFP, AAOS, ACSM, AMSSM, AOSSM, AOASM),35 36
2006, 2011
‘Concussion or mild traumatic brain injury (mTBI) is a pathophysiological process affecting the brain induced by direct or indirect biomechanical forces’.
Common features include:
  • Rapid onset of usually short-lived neurological impairment, which typically resolves spontaneously

  • Acute clinical symptoms that usually reflect a functional disturbance rather than structural injury

  • A range of clinical symptoms that may or may not involve LOC

  • Routine neuroimaging studies are typically normal

  • Clinical symptoms and signs (cognitive, somatic, affective, sleep disturbances)

Onset: rapid
Duration: short-lived
Mechanism of impairment: functional disturbance rather than structural injury
LOC: may or may not
Resolution: spontaneous
Neuroimaging: no abnormalities on standard structural neuroimaging
Combined definition for mTBI and concussionThis definition also comments on typical neuroimaging features in concussion.
Congress of Neurological Surgeons,37
1966
‘a clinical syndrome characterized by the immediate and transient post-traumatic impairment of neural function such as alteration of consciousness, disturbance of vision or equilibrium due to mechanical forces'.
  • Not specified

Onset: immediate
Duration: transient
Mechanism of impairment: not specified
LOC: may or may not
Resolution: not specified
Neuroimaging: not specified
Not specified
  • *In case of revised concussion definitions from the same group, the most recent version was considered if not stated otherwise.

  • AAFP, American Academy of Family Physicians; AAOS, American Academy of Orthopaedic Surgeons; ACSM, American College of Sports Medicine; AMSSM, American Medical Society for Sports Medicine; AOSSM, American Orthopaedic Society for Sports Medicine; AOASM, American Osteopathic Academy of Sports Medicine; LOC, loss of consciousness; mTBI, mild traumatic brain injury.