Concussion grading systems

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Concussion grading systems are sets of criteria used in sports medicine to determine the severity, or grade, of a concussion, the mildest form of traumatic brain injury. At least 16 such systems exist,[1] and there is little agreement among professionals about which is the best to use.[2] Several of the systems use loss of consciousness and amnesia as the primary determinants of the severity of the concussion.[2]

The systems are widely used to determine when it is safe to allow an athlete to return to competition. Concern exists that multiple concussions received in a short time may present an added danger, since an initial concussion may leave the brain in a vulnerable state for a time. Injured athletes are prohibited from returning to play before they are symptom-free during rest and exertion and their neuropsychological tests are normal again, in order to avoid a risk of cumulative effects such as decline in mental function and second-impact syndrome, which may occur on very rare occasions after a concussion that occurs before the symptoms from another concussion have resolved.

It is estimated that over 40% of high school athletes return to action prematurely[3] and over 40,000 youth concussions occur annually.[4] Concussions account for nearly 10% of sport injuries, and are the second leading cause of brain injury for young people ages 15–24.[5]

Three grading systems are followed most widely: the first by neurosurgeon Robert Cantu, another by the Colorado Medical Society, and a third by the American Academy of Neurology.[6] The Cantu system has become somewhat outdated.

American Academy of Neurology guidelines[edit]

The guidelines devised in 1997 by the American Academy of Neurology (AAN) were based on those formulated by the Colorado Medical Society.,[7] however, in 2013 the AAN published a revised set of guidelines that moved away from concussion grading, emphasizing more detailed neurological assessment prior to return to play.[8] The guidelines emphasized that younger patients should be managed more conservatively and that risk of recurrent concussion was highest within 10 days following the initial injury. Risk of concussion was also stratified by sport, training time, and player Body Mass Index.

The guideline also called into question the existence of the "second impact syndrome," proposing instead that athletes with a previous concussion may be more vulnerable to severe injury due to decreased reaction time and coordination, symptoms of the initial injury.

Colorado Medical Society guidelines[edit]

The Colorado Medical Society guidelines were published in 1991 in response to the death of a high school athlete due to what was thought to be second-impact syndrome.[9] According to the guidelines, a grade I concussion consists of confusion only, grade II includes confusion and post-traumatic amnesia, and grade III and IV involve a loss of consciousness.[2]

By these guidelines, an athlete who has suffered a concussion may return to sports after having been free of symptoms, both at rest and during exercise, as shown in the following table:[10][11]

Colorado Medical Society guidelines for return to play
Grade First concussion Subsequent concussions
I 15 minutes 1 week
II 1 week 2 weeks, with
physician approval
IIIa (unconscious
for seconds)
1 month 6 month, with
physician approval
IIIb (unconscious
for minutes)
6 months 1 year, with
physician approval

See also[edit]


  1. ^ Hayden MG, Jandial R, Duenas HA, Mahajan R, Levy M (2007). "Pediatric Concussions in Sports: A Simple and Rapid Assessment Tool for Concussive Injury in Children and Adults". Child's Nervous System 23 (4): 431–435. doi:10.1007/s00381-006-0277-2. PMID 17219233. 
  2. ^ a b c Cantu RC (2001). "Posttraumatic Retrograde and Anterograde Amnesia: Pathophysiology and Implications in Grading and Safe Return to Play". Journal of Athletic Training 36 (3): 244–248. PMC 155413. PMID 12937491. 
  3. ^ Concussions Extra Dangerous to Teen Brains, CNN, 4 February 2010
  4. ^ Heading Off Sports Injuries, Newsweek, 5 Feb 2010
  5. ^ High School Athletes Face Serious Concussion Risks, USA Today, 4 May 2009
  6. ^ Cobb S, Battin B (2004). "Second-Impact Syndrome". The Journal of School Nursing 20 (5): 262–7. doi:10.1177/10598405040200050401. PMID 15469376. 
  7. ^ Silver JM, McAllister TW, Yudofsky SC (2005). "Textbook Of Traumatic Brain Injury". American Psychiatric Pub., Inc. ISBN 1-58562-105-6. 
  8. ^ Giza CC, Kutcher JS, Ashwal S, et al. Summary of evidence-based guideline update: evaluation and management of concussion in sports: report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology 2013;80(24):2250–7. PMC 3721093
  9. ^ Collins MW, Iverson GL, Gaetz M, Lovell MR (2006). "24: Sport-Related Concussion.". In Zasler ND, Katz DI, and Zafonte RD. Brain Injury Medicine: Principles And Practice. Demos Medical Publishing, LLC. ISBN 1-888799-93-5. 
  10. ^ "Heads Up: Concussion in High School Sports: Management of Concussion in Sports". Centers for Disease Control and Prevention. Archived from the original on 2007-10-12. Retrieved 2008-01-07. 
  11. ^ Cuccurullo S, Ed. "Table 2-16. When to Return to Play—Colorado Medical Society Guidelines.". Physical Medicine and Rehabilitation Board Review. Demos Medical Publishing, Inc. Retrieved 2008-01-09. 

External links[edit]