Evidence of Concussion Signs in National Rugby League Match Play: a Video Review and Validation Study

Gardner et al. Sports Medicine - Open (2017) 3:29 DOI 10.1186/s40798-017-0097-9 ORIGINAL RESEARCH ARTICLE Open Access Evidence of Concussion Signs in National Rugby League Match Play: a Video Review and Validation Study Andrew J. Gardner1,9*, David R. Howell3,4,5, Christopher R. Levi1,2 and Grant L. Iverson6,7,8 Abstract Background: Many professional sports have introduced sideline video review to help recognise concussions. The reliability and validity of identifying clinical and observable signs of concussion using video analysis has not been extensively explored. This study examined the reliability and validity of clinical signs of concussion using video analysis in the National Rugby League (NRL). Methods: All 201 professional NRL matches from the 2014 season were reviewed to document six signs of possible concussion (unresponsiveness, slow to get up, clutching/shaking head, gait ataxia, vacant stare, and seizure). Results: A total of 127,062 tackles were reviewed. Getting up slowly was the most common observable sign (2240 times in the season, 1.8% of all tackles) but only 223 times where it appeared to be a possible concussion (0.2% of all tackles and 10.0% of the times it occurred). Additionally, clutching/shaking the head occurred 361 times (on 212 occasions this sign appeared to be due to a possible concussion), gait ataxia was observed 102 times, a vacant stare was noted 98 times, unresponsiveness 52 times, and a possible seizure 4 times. On 383 occasions, one or more of the observable signs were identified and deemed associated with a possible concussion. There were 175 incidences in which a player appeared to demonstrate two or more concussion signs, and 54 incidences where a player appeared to demonstrate three or more concussion signs. A total of 60 diagnosed concussions occurred, and the concussion interchange rule was activated 167 times. Intra-rater reliability (κ = 0.65–1.00) was moderate to perfect for all six video signs; however, the inter-rater reliability was not as strong (κ = 0.22–0.76). Most of the signs had relatively low sensitivity (0.18–0.75), but high specificity (0.85–1.00). Conclusions: Using video replay, observable signs of concussion appear to be sensitive to concussion diagnoses when reviewing known injuries among professional rugby league players. When reviewing an entire season, however, certain signs occur very commonly and did not identify concussion. Thus, the implementation of video review in the NRL is challenging, but can provide a useful addition to sideline concussion identification and removal from play decisions. Keywords: Concussion, Video analysis, Injury management, Return to play * Correspondence: 1 Centre for Stroke and Brain Injury, School of Medicine and Public Health, University of Newcastle, Callaghan, Australia 9 Priority Research Centre for Stroke and Brain Injury, Level 5, McAuley Building, Calvary Mater Hospital, Waratah, NSW 2298, Australia Full list of author information is available at the end of the article © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Gardner et al. Sports Medicine - Open (2017) 3:29 Key Points  The addition of video review to the assessment of concussion injury events may help improve consistency in the management of players, as well as assist in diagnostic decision-making in cases where signs may be transient and resolved by the time of the medical assessment.  The signs of concussion appear to be quite sensitive to concussion when reviewing known injuries; however, when reviewing an entire season, some signs occur very commonly and usually do not reflect a concussive injury.  Most signs of concussion had high specificity but low sensitivity when examining all tackles across a sporting season. Background Participation in many full contact and collision sports, such as rugby league, carries with it a risk of concussion [10]. In-game concussion diagnosis, however, remains a highly challenging task for the athletic trainer and sports medicine physician. On-field or sideline clinical assessments can be challenging due to the heterogeneous presentation of an athlete following a head impact, the non-specific nature of many of the clinical signs and symptoms of concussion [29], the absence of a reliable concussion biomarker [40], and the regularity with which some concussion signs emerge and evolve over time [31]. Recognising a potential concussion and removing an athlete from play is understood to be an important intervention for reducing the risk of a worse clinical outcome following injury [31]. However, it is acknowledged that in some instances, concussions may be missed from the sideline [25]. This may occur for a variety of reasons, but commonly the transient early physical signs may resolve before the player can be removed from play and assessed [25]. Some prior studies suggest that worse outcomes following concussion are associated with on-field signs and symptoms, such as loss of consciousness [28], amnesia [8, 28], mental status change for more than 5 min [8], and dizziness [23]. It is important to appreciate that the literature on the association between on-field signs and symptoms is mixed. For example, loss of consciousness has been associated with worse clinical outcomes in some [1, 4, 15, 28, 35, 39], but not in most studies [2, 3, 5, 8, 9, 16, 18, 22, 27, 30, 32, 36–38, 42, 43]. The vast majority of studies examining loss of consciousness base this finding on a questionnaire or interview completed with the athlete, not video review of the injury event for confirmation. Similarly, post-traumatic amnesia has been associated with worse clinical outcomes in some [15, 24, 28], but not in most studies [1–3, 8, 16, 18, 23, 27, 30, Page 2 of 10 34, 37, 38, 42]. Dizziness has been observed as an onfield symptom associated with a protracted recovery of greater than 21 days (6.34 time more likely) [23], but assessing dizziness is subjective and may or may not manifest as an objective sign (e.g., gait ataxia). Thus, video review may allow for the quantification of objective concussion signs, but not subjective symptoms. In the sport of rugby league, the concussion incidence rates have been reported to vary widely depending on the level of competition [10]. In one study of three National Rugby League (NRL) clubs, a concussion incidence rate of 14.8 concussions per 1000 player match hours was reported [13], while a rate of 28.3 concussion per 1000 player match hours were reported from one NRL club over a 15-year (1998–2012) period [41]. The use of video footage on the sideline for reviewing a concus (...truncated)