National Football League (NFL), National Hockey League (NHL), Chronic Traumatic Encephalopathy (CTE), Sport Concussion Assessment Tool (SCAT)

Hockey players are tough and gritty athletes. Ask any veteran – hockey encourages a “warrior mentality” in which players are respected for masking pain through crashes, body-checks, and fighting. What are the consequences of this hardy style of play? The topic of concussion in the National Football League (NFL) has made headway in the media over the past decade after class-action lawsuits were filed against the concealment of the traumatic effects of NFL head injuries [1]. However, less attention has been addressed to the incidence and long-term consequences of concussion in the National Hockey League (NHL).

In February of 2015, 10-year veteran NHL defense man Steve Montador was found deceased in his home at the age of 35 years old [2]. A brain autopsy revealed Chronic Traumatic Encephalopathy (CTE), a disease associated with memory loss, dementia, and depression. Steve Montador is likely not alone in this development amongst NHL athletes. Montador was the fifth NHL player to be diagnosed post-mortem with CTE, which supports academic claims that repeat concussion places hockey players at high risk of developing CTE [1,3-5]. Concussion has been defined as a pathophysiological brain response presenting with one or more of the following symptoms: headache, dizziness, vomiting, cognitive dysfunction, gait disturbance, loss of memory, ringing in the ears, blurred vision, fatigue, and irritability [4-6]. The predominant mechanism of concussion is described as a biomechanical force to the head, neck or face in which a shearing force causes rapid compression and deformation of the brain [7,18-20]. As an aggressive sport with player speeds measured as high as 30 kilometers per hour [11], ice hockey has demonstrated the highest concussion rates across contact sports [7,11-12]. Concussion incidence alone accounts for 2-14% of total hockey injuriesacross all ages [7,13-16]. The NHL made its first attempt to monitor concussion rates by launching the Concussion Program in 1997 to diagnose, assess, and track concussion in professional North American hockey [5-7]. Given its persistent impairment to professional careers, publicized primarily among elite players like Sidney Crosby [3], it is worthwhile to question what improvement the NHL has made with concussion.

The 1997 NHL Concussion Program required all NHL teams to submit standardized injury reports to document concussions diagnosed by team physicians [5-7]. A systematic review of seven independent studies reportedreportedan increasing mean number of concussions per NHL hockey season, from 11.6 concussions per season during the 1986-1996 seasons to a range of44 – 97 concussions per season in the 1996-2012 seasons [7]. Since the enactment of the 1997 Concussion Program,NHL concussions have risen from 2.5 of every 100 NHL games in 1997-98 to 4.9 of every 100 NHL games in 2011-12 [5]. Rule 48 was created during the 2010-11 season and made body-checks to the head illegal; however, concussion rates have not decreased since its implementation [5,7,8]. Why might NHL concussion rates be on the rise? Currently, we do not seem to have an answer.

Positive risk factors for concussion have been defined as player fatigue [21], playing the forward position [6], age [21], and an overall increase in athlete size, speed, and strength of NHL players [6]. However, perhaps the greatest challenge in concussion assessment in the NHL is the ambiguity of outcome measurement (i.e. diagnosis) by medical professionals and researchers [7]. With regard to reporting concussion incidence, the NHL has not disclosed concussion data publically under the protection of medical confidentiality [6,7,9]. Since the adoption of the 1997 NHL Concussion Program, only two studies from data collected directly from team physicians have been reported [7]. The first was an abstract by Meeuwisse, Burke and Benson (2003), which released data from the first five years following the program commencement. It reported a mean of 97 concussions/season and a median of two games missed following each concussion [17]. The second study was aprospective case series across the 1997-2004 seasons by Benson et al. in which NHL physicians reported an average of 80 concussions/season with a median of six days lost from play per concussion [6].

As the Concussion Program continues to adapt with new knowledge regarding concussion in contact sports, the NHL should seek to establish a common protocol in the way concussions are both diagnosed and reported. Current methodology of concussion in the NHL may be skewed by player underreporting of their symptoms and inaccurate diagnosis due to broadly defined criteria for concussion [6,7]. The NHL has not developed a standardized concussion diagnosis protocol. Its current definition of concussion includes a broad spectrum of symptoms open to the interpretation of individual team physicians who are under salary of the National Hockey League [6]. The issues regarding concussion reporting and the limited public access to concussion data have created challenges in collecting consistent concussion data. Independent researchers have used a variety of ways to study concussion, ranging from media collection of sport websites such as Roto world or The Hockey News [6,9-10] to reviews of digital videos of game play [8,16]. Standardization of NHL concussion diagnosis and reporting protocol would likely reduce concussion outcome bias due to these discrepancies.

Conclusions

Standardization of NHL concussion diagnosis is recommended, either through a third-party physician or by using established protocol such as the Sport Concussion Assessment Tool (SCAT). Possible solutions include implementing concussion grade scales for team physicians and an NHL concussion database that can be accessed with permission from the NHL for research purposes. These modifications should be considered before making formal changes to the rules of hockey, such as eliminating body-checking or changing the dimensions of ice rinks. These improvements would clarify our understanding of concussion trends in the NHL and help determine whether hockey is becoming more dangerous, or rather has an inherent concussion risk that participants must acknowledge before play.

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