Chronic traumatic encephalopathy neuropathologic change in former Australian rugby players.

AIMS: We applied the 2021 consensus criteria for both chronic traumatic encephalopathy neuropathological change and traumatic encephalopathy syndrome in a small case series of six former elite-level Australian rugby code players. METHODS: Neuropathological assessment of these cases was carried out at the Sydney and Victorian Brain Banks. Clinical data were collected via clinical interviews and health questionnaires completed by the participants and/or their next of kin, and neuropsychological testing was conducted with participants who were capable of completing this testing. RESULTS: All cases exhibited progressive cognitive impairment during life. Chronic traumatic encephalopathy neuropathological change was identified in four out of the six cases. However, coexisting neuropathologies were common, with limbic-predominant age-related TDP-43 encephalopathy and ageing-related tau astrogliopathy seen in all cases, intermediate or high Alzheimer's disease neuropathological change seen in four cases and hippocampal sclerosis seen in two of the six cases. CONCLUSION: The presence of multiple neuropathologies in these cases complicates clinical diagnostic efforts for traumatic encephalopathy syndrome. It will be important for further clinicopathological studies on larger groups to report all neuropathological comorbidities found in cases diagnosed with either chronic traumatic encephalopathy neuropathological change and/or traumatic encephalopathy syndrome.

Incidence of Concussion and Time to Return-to-Play in the National Rugby League.

OBJECTIVES: To examine the rates of concussion and recovery time over the course of 2 seasons of the National Rugby League (NRL). DESIGN: Descriptive cohort study. SETTING: The NRL match play concussion injury surveillance system. PARTICIPANTS: All NRL players who participated in the 2017 and 2018 season. MAIN OUTCOME MEASURES: The (1) frequency of sideline injury surveillance identified head impact events in real-time during the games, (2) frequency of head injury assessments conducted by the medical staff, (3) frequency of medically diagnosed concussions, (4) number of days to medical clearance to return-to-play, and (5) number of games missed after concussion. MAIN RESULTS: There were 472 head injury assessments conducted during the games and 149 medically diagnosed concussions over the course of 2 NRL seasons (1 concussion every 2.70 games). The median number of days until medical clearance was 6 (M = 6.85, SD = 8.03, interquartile range = 4-7; range = 0-79 days). There was a statistically significant difference in the number of days to be medically cleared to return to full contact or match play between seasons (U = 3517.00, P = 0.001), and the percentage of players medically cleared to return-to-play at 5 days after injury was 60.6% in 2017 and 27.6% in 2018. Most players (87.9%) did not miss a game after injury. CONCLUSIONS: There is approximately one concussion sustained for every 3 games in the NRL. Most players are medically cleared to return-to-play in 4 to 7 days.

Risk of Misdiagnosing Chronic Traumatic Encephalopathy in Men With Depression.

OBJECTIVE: In recent years, it has been proposed that depression represents one clinical subtype of chronic traumatic encephalopathy (CTE). This is the first study to examine the specificity of the research criteria for the clinical diagnosis of CTE in men with depression from the general population. METHODS: Data from the National Comorbidity Survey Replication, an in-person survey that examined the prevalence and correlates of mental disorders in the United States, were used for this study. Men diagnosed as having a major depressive episode in the past 30 days were included (N=101; mean age=39.4 years, SD=12.9, range=18-71). They were deemed to meet research criteriafor CTE if they presented with the purported supportive clinical features of CTE (e.g., impulsivity and substance abuse, anxiety, apathy, suicidality, and headache). RESULTS: Approximately half of the sample (52.5%) met the proposed research criteria for CTE (i.e., traumatic encephalopathy syndrome). If one accepts the delayed-onset criterion as being present, meaning that the men in the sample were presenting with depression years after retirement from sports or the military, then 83.2% of this sample would meet the research criteria for diagnosis. CONCLUSIONS: The clinical problems attributed to CTE, such as depression, suicidality, anxiety, anger control problems, and headaches, co-occurred in this sample of men with depression from the general population-illustrating that these problems are not specific or unique to CTE. More research is needed to determine whether depression is, in fact, a clinical subtype of CTE.

Chronic traumatic encephalopathy neuropathology might not be inexorably progressive or unique to repetitive neurotrauma.

In the 20th century, chronic traumatic encephalopathy (CTE) was conceptualized as a neurological disorder affecting some active and retired boxers who had tremendous exposure to neurotrauma. In recent years, the two research groups in the USA who have led the field have asserted definitively that CTE is a delayed-onset and progressive neurodegenerative disease, with symptoms appearing in midlife or decades after exposure. Between 2005 and 2012 autopsy cases of former boxers and American football players described neuropathology attributed to CTE that was broad and diverse. This pathology, resulting from multiple causes, was aggregated and referred to, in toto, as the pathology 'characteristic' of CTE. Preliminary consensus criteria for defining the neuropathology of CTE were forged in 2015 and published in 2016. Most of the macroscopic and microscopic neuropathological findings described as characteristic of CTE, in studies published before 2016, were not included in the new criteria for defining the pathology. In the past few years, there has been steadily emerging evidence that the neuropathology described as unique to CTE may not be unique. CTE pathology has been described in individuals with no known participation in collision or contact sports and no known exposure to repetitive neurotrauma. This pathology has been reported in individuals with substance abuse, temporal lobe epilepsy, amyotrophic lateral sclerosis, multiple system atrophy, and other neurodegenerative diseases. Moreover, throughout history, some clinical cases have been described as not being progressive, and there is now evidence that CTE neuropathology might not be progressive in some individuals. Considering the current state of knowledge, including the absence of a series of validated sensitive and specific biomarkers, CTE pathology might not be inexorably progressive or specific to those who have experienced repetitive neurotrauma.

The association between multiple prior concussions, cognitive test scores, and symptom reporting in youth rugby league players.

Objective: To examine the effect of prior concussion history on cognitive test performance and concussion symptom reporting among adolescent youth rugby league athletes.Participants: Participants were male elite level youth rugby league players (N = 73; Mean Age = 15.8; SD = 0.9; range = 14-18 years).Main Outcome Measure: CogSport performance based on participants group; those who reported no previous concussions (n = 30),1-2 previous concussions (n = 19), and ≥3 previous concussions (n = 29).Results: 73 participants with valid CogSport scores were included in the cognitive analyses. All participants were included in the symptom analyses. There were no differences between the groups with 0,1-2, or ≥3 previous concussions for processing speed, attention, learning, or working memory. There was atrend for those with multiple prior concussions to report more baseline preseason symptoms.Conclusions: There were no differences in scores on the CogSport test among those with ahistory of 0,1-2, or ≥3 prior concussions. Consistent with prior studies, youth with ahistory of multiple past concussions are more likely to endorse baseline preseason symptoms.

Effects of Exercise on Sport Concussion Assessment Tool-Third Edition Performance in Women.

OBJECTIVE: The purpose of this study was to examine the influence of a brief exercise protocol on Sport Concussion Assessment Tool-Third Edition (SCAT3) performance in amateur women athletes. DESIGN: Cross-over repeated-measures design. SETTING: Off-season, uninjured community amateur athletes. PARTICIPANTS: We examined 87 amateur women athlete volunteers (age = 29.9, SD = 6.9 years). INDEPENDENT VARIABLES: Participants were assessed using the SCAT3 under 2 conditions: at rest and after a 5-minute physical exertion protocol, completed in a counterbalanced order. MAIN OUTCOME MEASURES: Participants' performance on the various components of the SCAT3 under the 2 conditions: at rest and after a 5-minute physical exertion protocol. RESULTS: No significant differences were detected between at-rest and postexercise conditions for the balance, orientation, or cognitive components of the SCAT3. There were no significant differences in the proportion of participants who endorsed specific symptoms at rest compared with the postexercise condition (P > 0.05). However, women athletes who rated their exertion after exercise as "hard" or greater (Borg scale rating 13-20) reported significantly greater blurred vision (M = 0.25, SD = 0.62 vs M = 0.00, SD = 0.00; P = 0.006) and fatigue/low energy (M = 1.38, SD = 1.17 vs M = 0.66, SD = 0.91; P = 0.002) symptoms after exercise than those who rated their exertion as "light" or lower (Borg scale rating 6-12). CONCLUSIONS: In this study of women athletes, a brief bout of exercise did not seem to adversely affect SCAT3 performance and had only small effects on self-reported symptoms. There were differences in symptom reporting, however, in the subgroup of women who rated their exertion levels as "hard" or greater; they reported more blurred vision and fatigue/low energy.

Anger and Depression in Middle-Aged Men: Implications for a Clinical Diagnosis of Chronic Traumatic Encephalopathy.

OBJECTIVE: In recent years, it has been proposed that problems with anger control and depression define clinical features of chronic traumatic encephalopathy (CTE). The authors examined anger problems and depression in middle-aged men from the general population and related those findings to the proposed clinical criteria for CTE. METHODS: A sample of 166 community-dwelling men ages 40-60 was extracted from the normative database of the National Institutes of Health Toolbox. All participants denied prior head injury or traumatic brain injury (TBI). Participants completed scales assessing anger, hostility, aggression, anxiety, and depression. RESULTS: In response to the item "I felt angry," 21.1% of men reported "sometimes," and 4.8% reported "often." When asked "If I am provoked enough I may hit another person," 11.4% endorsed the statement as true. There were moderate correlations between anger and anxiety (Spearman's ρ=0.61) and between depression and affective anger (ρ=0.51), hostility (ρ=0.56), and perceived hostility (ρ=0.35). Participants were dichotomized into a possible depression group (N=49) and a no-depression group (N=117) on the basis of the question "I feel depressed," specific to the past 7 days. The possible depression group reported higher anxiety (p<0.001, Cohen's d=1.51), anger (p<0.001, Cohen's d=0.96), and hostility (p<0.001, Cohen's d=0.95). CONCLUSIONS: Some degree of anger and aggression are reported by a sizable minority of middle-aged men in the general population with no known history of TBI. Anger and hostility are correlated with depression and anxiety, indicating that all tend to co-occur. The base rates and comorbidity of affective dysregulation in men in the general population is important to consider when conceptualizing CTE phenotypes.

Traumatic Brain Injury Results in Cellular, Structural and Functional Changes Resembling Motor Neuron Disease.

Traumatic brain injury (TBI) has been suggested to increase the risk of amyotrophic lateral sclerosis (ALS). However, this link remains controversial and as such, here we performed experimental moderate TBI in rats and assessed for the presence of ALS-like pathological and functional abnormalities at both 1 and 12 weeks post-injury. Serial in-vivo magnetic resonance imaging (MRI) demonstrated that rats given a TBI had progressive atrophy of the motor cortices and degeneration of the corticospinal tracts compared with sham-injured rats. Immunofluorescence analyses revealed a progressive reduction in neurons, as well as increased phosphorylated transactive response DNA-binding protein 43 (TDP-43) and cytoplasmic TDP-43, in the motor cortex of rats given a TBI. Rats given a TBI also had fewer spinal cord motor neurons, increased expression of muscle atrophy markers, and altered muscle fiber contractile properties compared with sham-injured rats at 12 weeks, but not 1 week, post-injury. All of these changes occurred in the presence of persisting motor deficits. These findings resemble some of the pathological and functional abnormalities common in ALS and support the notion that TBI can result in a progressive neurodegenerative disease process pathologically bearing similarities to a motor neuron disease.

Video and clinical screening of national rugby league players suspected of sustaining concussion.

PRIMARY OBJECTIVE: This study reviewed the available sideline Sport Concussion Assessment Tool-Third Edition (SCAT3) performance of players who were removed from play using the 'concussion interchange rule' (CIR), the available video footage of these incidences, and associated return to play and concussion diagnosis decisions. RESEARCH DESIGN: Descriptive, observational case series. METHODS AND PROCEDURES: Data were collected from all NRL players who used the CIR during the 2014 season. MAIN OUTCOMES AND RESULTS: Complete SCAT3 and video analysis data were available for 38 (23%) of 167 uses of the concussion interchange rule, of which 20 (52.6%) players were medically diagnosed with concussion. Those with video evidence of unresponsiveness performed more poorly on the modified Balance Error Scoring System (M-BESS; p = .04; Cohen's d = .69) and reported greater symptoms (p = .03; d = .51). Similarly, players with a vacant stare reported greater symptoms (p = .05; d = .78). Those who demonstrated three signs (unresponsiveness, vacant stare and gait ataxia) performed more poorly on the M-BESS (p = .03; d = 1.4) and reported greater symptoms than those with no observable signs (p = .03; d = 1.4). CONCLUSIONS: The SCAT3 is sensitive to the acute effects of concussion in professional athletes; however, a minority of injured athletes might go undetected by this test.

Predictors of clinical recovery from concussion: a systematic review.

OBJECTIVE: A systematic review of factors that might be associated with, or influence, clinical recovery from sport-related concussion. Clinical recovery was defined functionally as a return to normal activities, including school and sports, following injury. DESIGN: Systematic review. DATA SOURCES: PubMed, PsycINFO, MEDLINE, CINAHL, Cochrane Library, EMBASE, SPORTDiscus, Scopus and Web of Science. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies published by June of 2016 that addressed clinical recovery from concussion. RESULTS: A total of 7617 articles were identified using the search strategy, and 101 articles were included. There are major methodological differences across the studies. Many different clinical outcomes were measured, such as symptoms, cognition, balance, return to school and return to sports, although symptom outcomes were the most frequently measured. The most consistent predictor of slower recovery from concussion is the severity of a person's acute and subacute symptoms. The development of subacute problems with headaches or depression is likely a risk factor for persistent symptoms lasting greater than a month. Those with a preinjury history of mental health problems appear to be at greater risk for having persistent symptoms. Those with attention deficit hyperactivity disorder (ADHD) or learning disabilities do not appear to be at substantially greater risk. There is some evidence that the teenage years, particularly high school, might be the most vulnerable time period for having persistent symptoms-with greater risk for girls than boys. CONCLUSION: The literature on clinical recovery from sport-related concussion has grown dramatically, is mostly mixed, but some factors have emerged as being related to outcome.

A systematic review of potential long-term effects of sport-related concussion.

OBJECTIVE: Systematic review of possible long-term effects of sports-related concussion in retired athletes. DATA SOURCES: Ten electronic databases. STUDY SELECTION: Original research; incidence, risk factors or causation related to long-term mental health or neurological problems; individuals who have suffered a concussion; retired athletes as the subjects and possible long-term sequelae defined as >10 years after the injury. DATA EXTRACTION: Study population, exposure/outcome measures, clinical data, neurological examination findings, cognitive assessment, neuroimaging findings and neuropathology results. Risk of bias and level of evidence were evaluated by two authors. RESULTS: Following review of 3819 studies, 47 met inclusion criteria. Some former athletes have depression and cognitive deficits later in life, and there is an association between these deficits and multiple prior concussions. Former athletes are not at increased risk for death by suicide (two studies). Former high school American football players do not appear to be at increased risk for later life neurodegenerative diseases (two studies). Some retired professional American football players may be at increased risk for diminishment in cognitive functioning or mild cognitive impairment (several studies), and neurodegenerative diseases (one study). Neuroimaging studies show modest evidence of macrostructural, microstructural, functional and neurochemical changes in some athletes. CONCLUSION: Multiple concussions appear to be a risk factor for cognitive impairment and mental health problems in some individuals. More research is needed to better understand the prevalence of chronic traumatic encephalopathy and other neurological conditions and diseases, and the extent to which they are related to concussions and/or repetitive neurotrauma sustained in sports.

MR Spectroscopy Findings in Retired Professional Rugby League Players.

The aim of this study was to examine brain neurometabolite concentrations in retired rugby league players who had a history of numerous self-reported concussions. Participants were 16 retired professional rugby league players (ages 30-45 years) with an extensive history of concussion and participation in contact sports, and 16 age- and education-matched controls who had no history of neurotrauma or participation in contact sports. All completed a clinical interview, psychological and cognitive testing, and magnetic resonance spectroscopy (MRS) investigation. MRS voxels were placed in posterior cingulate grey matter and parietal white matter. Neurometabolite concentrations were quantified using LCModel. It was hypothesized that retired athletes would differ on N-acetyl aspartate, myo-inositol, choline, glutamate, and glutathione. Retired players had significantly lower concentrations of grey matter glutathione (p=0.02, d=0.91). They did not significantly differ in concentrations of other neurometabolites. There were no significant differences between groups on measures of depression, anxiety, or cognitive functioning. The retired athletes reported significantly greater alcohol use (p<0.01; Cohen's d=1.49), and they had worse manual dexterity using their non-dominant hand (p=0.03; d=1.08). These preliminary findings suggest that MRS might be modestly sensitive to biochemical differences in athletes after their athletic careers have ended in the absence of clinical differences in cognitive performance and self-reported psychological functioning.

A preliminary video analysis of concussion in the National Rugby League.

PRIMARY OBJECTIVE: To conduct the first video analysis of concussion in the Australian National Rugby League (NRL) and describe player and injury characteristics, situational factors and time to return to play. RESEARCH DESIGN: Descriptive, observational case series. METHODS AND PROCEDURES: Video analysis of 20 medically diagnosed concussions for three consenting clubs during the 2013 NRL season. MAIN OUTCOME AND RESULTS: Most concussions (83%) occurred during a high tackle, and all injured ball carriers were hit high. Loss of consciousness was observed in 30% of cases. Common observable signs of injury included clutching of the head, balance problems or wobbly legs and a blank or vacant state. There were no post-concussive seizures. All players with loss of consciousness were removed from play. However, only half of the total sample was removed from play and one athlete who was removed returned to play in the same match. Of the players who were removed from play, the large majority returned the following week. Illegal play accounted for 25% of all concussions. CONCLUSIONS: Video analysis may be a useful method to study the incidence, mechanism and management of concussion in sports such as Rugby League. Future studies may include larger numbers to validate this preliminary data and may also investigate other levels of play and age ranges.

Cerebrovascular reactivity assessed by transcranial Doppler ultrasound in sport-related concussion: a systematic review.

BACKGROUND: Traumatic brain injury influences regulation of cerebral blood flow in animal models and in human studies. We reviewed the use of transcranial Doppler ultrasound (US) to monitor cerebrovascular reactivity following sport-related concussion. REVIEW METHOD: A narrative and systematic review of articles published in the English language, from December 1982 to October 2013. DATA SOURCES: Articles were retrieved via numerous databases using relevant key terms. Observational, cohort, correlational, cross-sectional and longitudinal studies were included. RESULTS: Three publications met the criteria for inclusion; these provided data from 42 athletes and 33 controls. All three studies reported reductions in cerebrovascular reactivity via transcranial Doppler US. CONCLUSIONS: These initial results support the use of cerebrovascular reactivity as a research tool for identifying altered neurophysiology and monitoring recovery in adult athletes. Larger cross-sectional, prospective and longitudinal studies are required to understand the sensitivity and prognostic value of cerebrovascular reactivity in sport-related concussion.

A multivariable analysis to predict variations in hospital mortality using systems-based factors of healthcare delivery to inform improvements to healthcare design within the English NHS.

Over the last decade, the strain on the English National Health Service (NHS) has increased. This has been especially felt by acute hospital trusts where the volume of admissions has steadily increased. Patient outcomes, including inpatient mortality, vary between trusts. The extent to which these differences are explained by systems-based factors, and whether they are avoidable, is unclear. Few studies have investigated these relationships. A systems-based methodology recognises the complexity of influences on healthcare outcomes. Rather than clinical interventions alone, the resources supporting a patient's treatment journey have near-equal importance. This paper first identifies suitable metrics of resource and demand within healthcare delivery from routinely collected, publicly available, hospital-level data. Then it proceeds to use univariate and multivariable linear regression to associate such systems-based factors with standardised mortality. Three sequential cross-sectional analyses were performed, spanning the last decade. The results of the univariate regression analyses show clear relationships between five out of the six selected predictor variables and standardised mortality. When these five predicators are included within a multivariable regression analysis, they reliably explain approximately 36% of the variation in standardised mortality between hospital trusts. Three factors are consistently statistically significant: the number of doctors per hospital bed, bed occupancy, and the percentage of patients who are placed in a bed within four hours after a decision to admit them. Of these, the number of doctors per bed had the strongest effect. Linear regression assumption testing and a robustness analysis indicate the observations have internal validity. However, our empirical strategy cannot determine causality and our findings should not be interpreted as established causal relationships. This study provides hypothesis-generating evidence of significant relationships between systems-based factors of healthcare delivery and standardised mortality. These have relevance to clinicians and policymakers alike. While identifying causal relationships between the predictors is left to the future, it establishes an important paradigm for further research.

Applying the Consensus Criteria for Traumatic Encephalopathy Syndrome Retrospectively to Case Studies of Boxers from the 20th Century.

There are no validated diagnostic criteria for traumatic encephalopathy syndrome (TES). During the early and middle 20th century, TES was described as a clinical condition that was experienced by some high-exposure boxers-and it was believed to reflect chronic traumatic brain injury. Consensus criteria for the diagnosis of TES were published in 2021. We applied the consensus criteria for TES retrospectively to cases of chronic brain damage in boxers described in articles published in the 20th century that were obtained from narrative and systematic reviews. The sample included 157 boxers identified in 21 articles published between 1929 and 1999. Two authors reviewed each case description and coded the criteria for TES. For the core clinical features, cognitive impairment was noted in 63.1%, and in 28.7% of cases the person's cognitive functioning appeared to be broadly normal. Neurobehavioral dysregulation was present in 25.5%. One third (34.4%) were identified as progressive, 30.6% were not progressive, and the course could not be clearly determined in 35.0%. In total, 29.9% met the TES consensus criteria, 28.0% did not, and 42.0% had insufficient information to make a diagnostic determination. TES, in the 20th century, was described as a neurological condition, not a psychiatric disorder-and this supports the decision of the 2021 consensus group to remove primary and secondary psychiatric diagnoses from being a core diagnostic feature. Future research is needed to determine whether, or the extent to which, cognitive impairment or neurobehavioral dysregulation described as characterizing TES are associated with chronic traumatic encephalopathy neuropathological change.

Tacklers' shoulder abduction and flexion at contact alter when engaging in different front-on, one-on-one tackle instructions from an expert coach.

OBJECTIVES: To ascertain how the three-dimensional shoulder kinematics of tacklers alter when performing four legal types of front-on, one-on-one, rugby-style torso tackles. DESIGN: Controlled laboratory study. METHODS: Three-dimensional motion capture measured 15 male amateur-level rugby code players (24.3 ±â€¯6.1 years) who were instructed by an expert coach to perform four sets of 10 front-on, one-on-one tackles. Four sets comprised two smother and two dominant tackles: two based on the Australian National Rugby League coaching manual (Dominant NRL, Smother NRL); and two modifications via increasing the contact height from the lower- to mid-torso (Dominant, Torso Stick) or from the upper- to mid-upper torso with a vertical 'pop action' that changes the way the tackler contacted the ball carrier's upper torso (Smother, Pop, Lock). Mixed general linear models were applied. RESULTS: Greater shoulder abduction, flexion and internal rotation were displayed by the DNRL tackle technique than in any other technique (p < 0.001). At contact, the Smother and Dominant NRL (p < 0.03) showed greater head-uptrunk contralateral rotation away from the tackle than the Smother, Pop, Lock. CONCLUSIONS: Tacklers modified the way they positioned their shoulder joint when engaging in legal front-on, one-on-one tackles with different tackle instructions. More prominent positions of shoulder abduction and flexion, and head-uptrunk contralateral rotation were observed when executing the traditional tackle techniques (Smother NRL, Dominant NRL) as opposed to two variants of these (Smother, Pop, Lock, Dominant, Torso Stick). Inclusion of tackle specific coaching instructions provides emerging scientific evidence to support revised coaching tackling technique interventions that might enhance player safety.

Tackle Risk Factors for Head Injury Assessments (HIAs) in Sub-Elite Rugby League and Recommendations for Prevention: Head Contacts from Upright Tackles Increase the HIA Risk to Both Ball Carrier and Tackler.

BACKGROUND: The rugby league tackle has been identified as the game event with the greatest propensity for a clinically diagnosed concussion. This study aims to replicate the work conducted in professional rugby league and rugby union by examining Head Injury Assessment (HIA) events to determine the associated tackle characteristics that increase concussion risk in sub-elite rugby league players. This comparison between competition levels is important due to the less developed physiological and tackle proficiency characteristics of sub-elite rugby league players and the fewer resources available for an on-field diagnosis, compared to the elite level of the sport. RESULTS: Tackles resulting in Head Injury Assessments (HIAs, n = 131) and 2,088 tackles that did not result in a head injury were identified and coded from one season of the 2019 Queensland Cup. The body position of both ball carrier and tackler, tackle height, and body contact areas were evaluated. The propensity for tacklers to undergo a head injury assessment was 1.49 HIAs per 1,000 tackles, equating to a 2.5-fold higher risk than that of the ball carrier (0.59 HIAs per 1,000 tackles). The risk for an HIA was 2.75-fold greater when the tackler was upright (2.89 HIAs per 1,000 tackles) compared to a bent-at-the-waist tackler (1.05 HIAs per 1,000 tackles). The greatest risk for the tackler and ball carrier sustaining an HIA occurred when the tackle height was high, with head-to-head contact having the greatest propensity for an HIA (44.37 HIAs per 1,000 tackles). HIA risk was also greater for both players when the ball carrier did not employ an evasion strategy (3.73 HIAs per 1,000 tackles). CONCLUSIONS: The study replicates results from research in elite rugby league and rugby union. A combination of higher head contact/proximity and upright body position significantly increase an HIA risk. Tackler head position and ball carrier evasion behaviours also affect risk, suggesting that injury prevention strategies designed to reduce tackle height and improve tackle technique by focusing on head position, body position, and in a novel finding, ball carrier evasion, may reduce head injury risk in sub-elite rugby league players.

Examining Whether Loss of Consciousness Is Associated With Worse Performance on the SCAT5 and Slower Clinical Recovery After Concussion in Professional Athletes.

Video surveillance has almost universally been employed by professional sports to identify signs of concussion during competition. This study examined associations between video-identified possible loss of consciousness (LOC), acute concussion evaluation findings, and recovery time in concussed professional rugby league players. Medical personnel and sideline video operators identified head impact events sustained during three seasons of National Rugby League (NRL) matches to determine the need for further medical evaluation. If a concussion was suspected, players were removed from play and underwent a Head Injury Assessment, including the Sports Concussion Assessment Tool, Fifth Edition (SCAT5). Video footage was later examined to identify signs of possible LOC (i.e., observed LOC, no protective action in the fall, and unresponsiveness or lying motionless). Possible LOC was identified in 99 of the 1706 head impact events (5.8%). The median duration of apparent unresponsiveness was 4.2 sec (M = 7.4, standard deviation [SD] = 12.8, interquartile range [IQR] = 2.5-6.6). In the 661 athletes for whom SCAT5 data were available, those with possible LOC endorsed more SCAT5 symptoms and performed worse on Maddocks questions, Standardized Assessment of Concussion (SAC) total scores, orientation, immediate recall, concentration, and delayed recall. For the 255 players with medically diagnosed concussions, SCAT5 data were available for 245. Concussed players with possible LOC performed significantly worse on Maddocks questions. However, there were no group differences in SCAT5 symptom endorsement, SAC total scores, orientation, immediate recall, concentration, delayed recall, or the modified version of the Balance Error Scoring System (mBESS) total errors. Further, the presence or absence of possible LOC was not associated with number of games missed or time to medical clearance for match play. The duration of possible LOC was not associated with the number of games missed or time to medical clearance for match play. According to video review in NRL players, brief LOC might be more common than previously thought. The present study reveals possible LOC is not predictive of missed games or time to recover following concussion.