Proceedings from the Ice Hockey Summit III: Action on Concussion

An objective neurophysiological study of subconcussion in female and male high school student athletes

Emerging evidence from neurophysiological brain vital sign studies show repeatable sensitivity to cumulative subconcussive impairments over a season of contact sports. The current study addressed the need for research comparing a low-contact control group to high-contact group. Importantly, the study also expanded the scope of neurophysiological changes related to repetitive head impacts to include female athletes in addition to male athletes. In total, 89 high school student athletes underwent 231 brain vital sign scans over a full calendar year. The results replicated prior subconcussive cognitive impairments (N400 delays) and sensory impairments (N100 amplitude reductions) in male athletes and demonstrated similar subconcussive impairments for the first time in female athletes. While there was no significant subconcussive difference between female and male athletes, female athletes show overall larger responses in general. The findings demonstrated that subconcussive impairments are detectable in a controlled experimental comparison for both female and male high school athletes. The study highlights the opportunity to monitor subconcussive changes in cognitive processing for both female and male athletes to help advance prevention, mitigation and management efforts aimed at reducing athletes' risk of potential long-term negative health outcomes related to cumulative exposure to repetitive head impacts.

Fighting in professional ice hockey: it's time for a change

Ice hockey has long been defined by a level of violence not seen in other sports. The rough-and-tough vigilante nature of the game was often employed as a method of enticing fans. Play in the National Hockey League (NHL) evolved throughout the 20th century as the rules governing it did. The nuances of what was allowed on the ice was slowly defined, but the league always fell short of an outright ban on fighting. Notably, the NHL allows fighting while international and Olympic leagues do not. Proponents of fighting's continued presence in the NHL argue that it can attract fans, facilitate momentum changes, help win games, and allows for social regulation on the ice. However, analyses of these theories have found little definitive evidence, calling the utility of fighting into question. The economics of fighting in hockey reveal high salary payouts, increased cost of injury, and a lack of correlation with ticket sales. Additionally, there is a concern for concussions sustained during fighting which has the potential for long term, detrimental mental health effects for athletes. In this analysis, we explore the history and evolution of fighting in the NHL, as well as the reasons behind its continued presence in the game, the risks associated with fighting, and the economics behind it all. Based upon these bodies of evidence, we make a proposal regarding the future of fighting in the NHL.

Fighting and Penalty Minutes Associated With Long-term Mortality Among National Hockey League Players, 1967 to 2022

Importance

National Hockey League (NHL) players are exposed to frequent head trauma. The long-term consequences of repetitive brain injury, especially for players who frequently engage in fighting, remains unknown.

Objective

To investigate the mortality rates and causes of death among NHL enforcers with more career fights and penalty minutes as compared with matched controls.

Design, Setting, and Participants

This matched cohort study examined 6039 NHL players who participated in at least 1 game in the seasons between October 11, 1967, and April 29, 2022, using official NHL data. Cohorts designated as enforcer-fighter (E-F) and enforcer-penalties (E-P) were selected. The E-F cohort consisted of players who participated in 50 or more career fights (n = 331). The E-P cohort included players with 3 or more penalty minutes per game (n = 183). Control-matched NHL players were identified for each E-F player (control-fighter [C-F]) (n = 331) and each E-P player (control-penalties [C-P]) (n = 183).

Exposures

Fighting and penalty minutes were both used as proxies for head trauma exposure. Players with significantly increased exposure to fighting and penalties (E-F and E-P cohorts) were compared with NHL players with less frequent exposure to head trauma (C-F and C-P cohorts).

Main Outcomes and Measures

Mortality rates and age at death of the enforcer and control cohorts, and their causes of death using data obtained from publicly available sources such as online and national news sources, including NHL.com.

Results

Among the 6039 NHL players identified (mean [SD] age, 47.1 [15.2] years), the mean (SD) number of fights was 9.7 (24.5). The mortality rates of E-F and C-F players (13 [3.9%] vs 14 [4.2%], respectively; P = .84) or E-P and C-P players (13 [7.1.%] vs 10 [5.5%]; P = .34) were not significantly different. The mean (SD) age at death was 10 years younger for E-F players (47.5 [13.8] years) and E-P players (45.2 [10.5] years) compared with C-F players (57.5 [7.1] years) and C-P players (55.2 [8.4] years). There was a difference in causes of death between the control and enforcer players (2 neurodegenerative disorders, 2 drug overdoses, 3 suicides, and 4 vehicular crashes among enforcers vs 1 motor vehicle crash among controls; P = .03), with enforcers dying at higher rates of overdose (2 of 21 [9.5%] vs 0 of 24) and suicide (3 of 21 [14.3%] vs 0 of 24) (P = .02).

Conclusions and Relevance

The findings of this matched cohort study indicate that there is no difference in overall mortality rates between NHL enforcers and controls. However, being an enforcer was associated with dying approximately 10 years earlier and more frequently of suicide and drug overdose.

National Hockey League Fights per Game and Viewership Trends: 2000-2020

Background

Though once considered an integral part of professional hockey, fighting carries significant health risks to players. Fighting has remained legal in the National Hockey League (NHL) due to its purported economic and entertainment value. However, fights per game have diminished over the past 20 years, challenging the necessity of fighting to promote fan attendance.

Hypothesis

Despite decreasing fighting rates, attendance has been stable and is negatively associated with fights per game.

Methods

Two public databases were reviewed to determine attendance, fighting majors, goals scored, and games played for each NHL team from 2000 to 2020 and averaged on a per game basis. Univariate analysis was used to evaluate relationships between attendance and fights, attendance and goals, as well as goals and fights.

Results

Fights per game decreased from a peak of 0.64 in 2002 to a low of 0.18 in 2020, while average attendance increased from a low of 16,549 in 2004 to a peak of 17,768 in 2013, before settling between 17,400 and 17,500 during the final three seasons of the study period. A significant negative correlation was found between attendance and fights per game (R = -0.6617, p = 0.0020). There was a positive, but not significant correlation between attendance and goals per game (R = 0.2457, p = 0.3105). A significant inverse correlation existed between goals per game and fights per game (R = -0.521, p = 0.0222).

Conclusions

NHL fighting rates have diminished during the past two decades, while fan attendance has increased. A significant negative correlation exists between fan attendance and fights per game, casting doubt on fighting's entertainment value. Meanwhile, a significant inverse correlation was noted between goals per game and fights per game. Taken together, these findings suggest fans may prefer higher scoring and less violent competitions. We conclude by suggesting that prohibiting fights in the NHL could improve player safety without negatively impacting fan attendance.

Validity Indices of the King-Devick Concussion Test in Hockey Players

OBJECTIVE

To compare the validity indices of the King-Devick (KD) test in hockey players using any increase in test time over baseline to a 6-second increase as a positive concussion test. We hypothesized the KD test using the 6-second change would yield greater validity indices.

DESIGN

Prospective observational cohort study.

SETTING

Sports complex.

PARTICIPANTS

Sixty-five male hockey players aged 13 to 20 years.

INDEPENDENT VARIABLE

Concussion diagnosis.

MAIN OUTCOME MEASURES

Time to complete the KD test. Sensitivity (SN), specificity (SP), and the positive likelihood ratios (LRs+) were calculated using 2 thresholds for a positive test: (1) any increase in time and (2) an increase of 6 seconds or greater.

RESULTS

Eighteen players (27.7%) were diagnosed with a concussion. Using any increase in time as a positive test yielded the following: SN 72.2%, SP 78.7%, LR+ 3.4, and LR- 0.4. Using the 6-second threshold yielded the following: SN 44.4%, SP 93.6%, LR+ 7.0, and LR- 0.6. A receiver operator curve analysis confirmed 6.40 seconds or greater maximized the LR+.

CONCLUSIONS

A 6-second or greater increase in the KD test performance provides greater validity in diagnosing concussion as compared with any increase in performance time.

The Impact of the Instigator Rule on Fighting in the National Hockey League

Background

Fighting is often considered an essential part of professional hockey. Increased ticket sales, a means to self-regulate other dangerous gameplay, and helping teams win are a few of the reasons that fighting advocates provide for retaining fighting in the NHL. However, fighting trends have changed over the past 50 years. Given the recent data on concussions and player safety, an in-depth analysis of fighting is required to understand if fighting has a place in the future of the NHL.

Methods

Seasonal statistical team data on NHL teams from the 1967 to 2019 seasons were collected and analyzed using publicly available databases. Specific outcome variables of interest related to fighting, penalties, the final team record for a given season, and final standing were recorded. The data were divided into subgroups according to "era of play" and before/after the implementation of the instigator rule. The trends in fighting, seasonal outcomes, and other minor penalties were assessed to determine the trends in fighting over the past 50 years, the relationship between fighting and winning, and the impact of the instigator rule.

Results

Fights per game decreased significantly after the implementation of the instigator rule (0.71 to 0.51 fights per game, p < 0.0001). There was no significant difference in fights per game when comparing Stanley Cup champions to nonplayoff teams in either the modern era (0.36 vs. 0.42, p = 0.43) or the expansion era (0.45 vs. 0.51, p = 0.49). Only two Stanley Cup champions (the Flyers 1974-1975 and the Ducks 2006-2007) led the league in fighting. A multivariate regression analysis comparing fights per game and points earned per season divided by the number of games played revealed a statistically significant inverse relationship (coefficient = -0.16, p < 0.001).

Conclusion

Our analysis demonstrates that the Instigator rule achieved its intended effect to decrease the number of fights per game. In the current era of professional hockey, there is no compelling evidence that a team with more fights per game will achieve greater seasonal success. These results continue to cast doubt on the belief that fighting is a necessary strategy for winning games at the NHL level.

Cervical Spine Injuries in the Ice Hockey Player: Current Concepts in Epidemiology, Management and Prevention

STUDY DESIGN

This review article examines the biomechanics that underly hockey-related cervical spine injuries, the preventative measures to curtail them, optimal management strategies for the injured player and return to play criteria.

OBJECTIVE

Hockey is a sport with one of the highest rates of cervical spine injury, but by understanding the underlying pathophysiology and context in which these injuries can occur, it is possible to reduce their incidence and successfully manage the injured player.

METHODS

Multiple online databases including PubMed, Google Scholar, Columbia Libraries Catalog, Cochrane Library and Ovid MEDLINE were queried for original articles concerning spinal injuries in ice hockey. All relevant papers were screened and subsequently organized for discussion in our subtopics.

RESULTS

Cervical fractures in ice hockey most often occur due to an increased axial load, with a check from behind the most common precipitating event.

CONCLUSIONS

Despite the recognized risk for cervical spine trauma in ice hockey, further research is still needed to optimize protocols for both mitigating injury risk and managing injured players.

Subconcussive brain vital signs changes predict head-impact exposure in ice hockey players

The brain vital signs framework is a portable, objective, neurophysiological evaluation of brain function at point-of-care. We investigated brain vital signs at pre- and post-season for age 14 or under (Bantam) and age 16-20 (Junior-A) male ice hockey players to (i) further investigate previously published brain vital sign results showing subconcussive cognitive deficits and (ii) validate these findings through comparison with head-impact data obtained from instrumented accelerometers. With a longitudinal study design, 23 male ice hockey players in Bantam (n = 13; age 13.63 ± 0.62) and Tier II Junior-A (n = 10; age 18.62 ± 0.86) divisions were assessed at pre- and post-season. None were diagnosed with a concussion during the season. Cognitive evoked potential measures of Auditory sensation (N100), Basic attention (P300) and Cognitive processing (N400) were analysed as changes in peak amplitudes and latencies (six standard scores total). A regression analysis examined the relationship between brain vital signs and the number of head impacts received during the study season. Significant pre/post differences in brain vital signs were detected for both groups. Bantam and Junior-A players also differed in number of head impacts (Bantam: 32.92 ± 17.68; Junior-A: 195.00 ± 61.08; P < 0.001). Importantly, the regression model demonstrated a significant linear relationship between changes in brain vital signs and total head impacts received (R = 0.799, P = 0.007), with clear differences between the Bantam and Junior-A groups. In the absence of a clinically diagnosed concussion, the brain vital sign changes appear to have demonstrated the compounding effects of repetitive subconcussive impacts. The findings underscored the importance of an objective physiological measure of brain function along the spectrum of concussive impacts.

Concussions in Ice Hockey - Moving Toward Objective Diagnoses and Point-of-care Treatment: A Review

The incidence of sport-related concussion coupled with a doubling of the participation rate in youth hockey over the past two decades provides impetus for the review of the most promising concussion treatment options. This narrative review summarizes the future treatment options for sport-related concussions in ice hockey, while acknowledging their generalizability to concussion in all sports. Symptom assessment, sign observation, as well as cognitive and balance testing, have historically been used to diagnose a concussion. These methods continue to improve, but the need for effective treatments is clear. Pharmacologic, transcranial light, and nutritional supplement treatment options for concussion warranting further investigation have been identified. Dimethyl fumarate is an immunomodulatory compound thought to trigger antioxidant gene expression. Memantine reduces apoptosis and astrogliosis by inhibiting the calcium influx into cells normally caused by glutamate's activation of N-methyl-D-aspartate receptors. Thioredoxin-mimetic peptides and transcranial photobiomodulation temper the effects of the energy crisis by acting as free radical scavengers. In addition, seven neuroprotective nutritional supplements have been identified: berberine, creatine, curcumin, melatonin, omega-3 fatty acids, resveratrol, and vitamins. An estimated US $1.1 billion has been spent on unsuccessful traumatic brain injury clinical trials. As our ability to accurately diagnose concussion improves, dimethyl fumarate, memantine, thioredoxin-mimetic peptides, transcranial photobiomodulation, and nutritional supplements (berberine, creatine, curcumin, melatonin, omega-3 fatty acids, resveratrol, and vitamins) warrant further preclinical and clinical examination in advancing the treatment of sport-related concussions.

Developing a Comprehensive, Interdisciplinary Concussion Program

There has been a growing trend of local and national coverage of and interest in concussion injuries over the past 2 decades. Increasing public concern over potential catastrophic and unknown long-term effects of sports-related concussion injuries has led to an acknowledgment of the strong public health need for addressing all concussion injuries, regardless of mechanism of injury. In efforts to address this need for concussion prevention and management, both in sports and nonsports, The University of Kansas Health System initiated the interdisciplinary Center for Concussion Management program in 2012. The program was created as a virtual clinic concept and includes voluntary participation from various providers across the institution, limited budget, and space obstacles. Since its inception, the program has continued to operate as its initial design of a multidisciplinary team model outside the sole ownership of 1 department, and has expanded to include education and outreach to local and regional schools and groups.