Editing Concussion (section)

==== Historical information on grading systems ====
In the past, the decision to allow athletes to return to participation was frequently based on the grade of concussion.<ref>{{cite web |title=Returning to Sports and Activities {{!}} HEADS UP {{!}} CDC Injury Center |url=https://www.cdc.gov/headsup/basics/return_to_sports.html |website=www.cdc.gov |access-date=14 November 2022 |language=en-us |date=12 February 2019}}</ref> However, current research and recommendations by professional organizations including the [[National Athletic Trainers' Association]] recommend against such use of these grading systems.{{Citation needed|date=May 2020}} Currently, injured athletes are prohibited from returning to play before they are symptom-free during both rest and exertion and until results of the [[neuropsychological test]]s have returned to pre-injury levels.<ref name="pmid24665227">{{cite journal | vauthors = Purcell LK | title = Sport-related concussion: Evaluation and management | journal = Paediatrics & Child Health | volume = 19 | issue = 3 | pages = 153–165 | date = March 2014 | pmid = 24665227 | pmc = 3959977 | doi = 10.1093/pch/19.3.153 }}</ref>
Three grading systems have been most widely followed: by Robert Cantu, the [[Colorado Medical Society]], and the [[American Academy of Neurology]].<ref name="cobb" /> Each employs three grades, as summarized in the following table:<ref name="cantu01" />
{| class="wikitable" style="margin: 1em auto 1em auto; text-align:center"
|+Comparison of historic concussion grading scales – not currently recommended for use by medical professionals
! Guidelines&nbsp;!! Grade&nbsp;I !! Grade&nbsp;II !! Grade&nbsp;III
|-
! Cantu
| width="25%" | Post-traumatic amnesia <30&nbsp;minutes, no loss of consciousness || width="25%" | Loss of consciousness <5&nbsp;minutes or amnesia lasting 30&nbsp;minutes–24&nbsp;hours || width="25%" | Loss of consciousness >5&nbsp;minutes or amnesia >24&nbsp;hours
|-
! Colorado Medical Society
| Confusion, no loss of consciousness || Confusion, post-traumatic amnesia, no loss of consciousness || Any loss of consciousness
|-
! American Academy of Neurology
| Confusion, symptoms last <15&nbsp;minutes, no loss of consciousness || Symptoms last >15&nbsp;minutes, no loss of consciousness || Loss of consciousness (IIIa, coma lasts seconds, IIIb for minutes)
|}
At least 41 systems measure the severity, or grade, of a mild head injury,<ref name="AndersonT" /> and there is little agreement about which is best.<ref name="cantu01" /> In an effort to simplify, the 2nd International Conference on Concussion in Sport, meeting in Prague in 2004, decided that these systems should be abandoned in favor of a 'simple' or 'complex' classification.<ref>{{cite journal | vauthors = McCrory P, Johnston K, Meeuwisse W, Aubry M, Cantu R, Dvorak J, Graf-Baumann T, Kelly J, Lovell M, Schamasch P | display-authors = 6 | title = Summary and agreement statement of the 2nd International Conference on Concussion in Sport, Prague 2004 | journal = British Journal of Sports Medicine | volume = 39 | issue = 4 | pages = 196–204 | date = April 2005 | pmid = 15793085 | pmc = 1725173 | doi = 10.1136/bjsm.2005.018614 }}</ref> However, the 2008 meeting in Zurich abandoned the simple versus complex terminology, although the participants did agree to keep the concept that most (80–90%) concussions resolve in a short period (7–10 days) and although the recovery time frame may be longer in children and adolescents.<ref name="2008 Consensus Statement" /><ref name="pmid23855364">{{cite journal | vauthors = McCrory P, Meeuwisse WH, Aubry M, Cantu RC, Dvořák J, Echemendia RJ, Engebretsen L, Johnston K, Kutcher JS, Raftery M, Sills A, Benson BW, Davis GA, Ellenbogen R, Guskiewicz KM, Herring SA, Iverson GL, Jordan BD, Kissick J, McCrea M, McIntosh AS, Maddocks D, Makdissi M, Purcell L, Putukian M, Schneider K, Tator CH, Turner M | display-authors = 6 | title = Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport, Zurich, November 2012 | journal = Journal of Athletic Training | volume = 48 | issue = 4 | pages = 554–575 | date = 2013 | pmid = 23855364 | pmc = 3715021 | doi = 10.4085/1062-6050-48.4.05 }}</ref>