Long-term effects of sports concussion

Questions : Cette thèse visait à répondre à deux questions fondamentales : 1) Est-ce que les athlètes qui présentent un historique de commotions cérébrales du sport en conservent des effets délétères à long terme? ; et 2) Est-ce que les effets néfastes des commotions cérébrales récurrentes sur le fonctionnement tant cognitif que moteur sont cumulatifs? Devis expérimental : À l’aide d’un plan d’investigation double-cohorte réalisé avec un groupe d’athlètes évoluant au niveau universitaire et un autre formé d’anciens athlètes universitaires testés plus de trois décennies plus tard, les quatre études qui composent cette thèse ont employé des méthodes raffinées d’investigation des fonctions cognitives et motrices pour en déceler des atteintes persistantes. Méthodologie : Les potentiels évoqués cognitifs ainsi que les tests neuropsychologiques ont permis de sonder le fonctionnement cognitif de ces athlètes alors que la stimulation magnétique transcrânienne, une plateforme de force permettant de mesurer la stabilité posturale ainsi qu’un système d’enregistrement tridimensionnel des mouvements rapides alternatifs ont servi à l’évaluation de l’intégrité du système moteur. Résultats : Cette thèse a permis de déceler des altérations persistentes et cumulatives des fonctions cognitives et motrices. De plus, ces subtiles atteintes observées chez les jeunes athlètes, affectant essentiellement des marqueurs neurophysiologiques sous-cliniques du fonctionnement cognitif et moteur, s’étaient accentuées chez les anciens athlètes universitaires qui montraient un déclin quantifiable tant des fonctions cognitives que motrices. Discussion : Ces résultats suggèrent d’une part que les commotions cérébrales du sport entraînent des altérations cognitives et motrices chroniques qui s’accentuent en fonction du nombre de commotions cérébrales subies. D’autre part, les effets délétères des commotions cérébrales du sport sur le fonctionnement cognitif et moteur combinés à ceux associés au processus de vieillissement entraînent un déclin cognitif et moteur quantifiable en comparaison aux anciens athlètes n’ayant jamais subi de commotions cérébrales.

The long term effects of sports concussion on retired Australian football players: a study using Transranial Magnetic Stimulation

This study investigated corticomotor excitability and inhibition, cognitive functioning, and fine motor dexterity in retired elite and amateur Australian football (AF) players who had sustained concussions during their playing careers. Forty male AF players who played at the elite level (n=20; mean age 49.7±5.7 years) or amateur level (n=20; mean age 48.4±6.9 years), and had sustained on average 3.2 concussions 21.9 years previously, were compared with 20 healthy age-matched male controls (mean age 47.56±6.85 years). All participants completed assessments of fine dexterity, visuomotor reaction time, spatial working memory (SWM), and associative learning (AL). Transcranial magnetic stimulation (TMS) was used to measure corticospinal excitability: stimulus-response (SR) curves and motor evoked potential (MEP) 125% of active motor threshold (aMT); and intracortical inhibition: cortical silent period (cSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI). Healthy participants performed better in dexterity (p=0.003), reaction (p=0.003), and movement time (p=0.037) than did both AF groups. Differences between AF groups were found in AL (p=0.027) and SWM (p=0.024). TMS measures revealed that both AF groups showed reduced cSP duration at 125% aMT (p>0.001) and differences in SR curves (p>0.001) than did healthy controls. Similarly, SICI (p=0.012) and LICI (p=0.009) were reduced in both AF groups compared with controls. Regression analyses revealed a significant contribution to differences in motor outcomes with the three measures of intracortical inhibition. The measures of inhibition differed, however, in terms of which performance measure they had a significant and unique predictive relationship with, reflecting the variety of participant concussion injuries. This study is the first to demonstrate differences in motor control and intracortical inhibition in AF players who had sustained concussions during their playing career two decades previously.

From Management to Prevention: the New Cure for Sports Concussion

A case for directing attention away from concussion management and towards the prevention of concussions in sport.

Neuroimaging and electrophysiology efficacy in measuring acute effects and long-term sequelae following sports-related concussion

Traumatic brain injury (TBI) is a complex pathophysiological process resulting from external forces applied to the skull and affecting the brain. TBI is a significant global contributor to disability and death, particularly in children and young adults. The severity of a TBI may range from "mild" (a brief change in mental status or consciousness) to "severe" (an extended period of unconsciousness or amnesia after the injury), with mild TBI (mTBI) the most common form, diagnosed in 80-90% of cases. Sports-related concussion contributes significantly to mTBI accounting for nearly 20% of all mTBI cases. In the past decade there has been increasing growing public concern regarding the association of sports concussion; in particular further chance of recurrent injury following a concussion due to transient cognitive impairments, and long-term detrimental mental health issues and deterioration in brain function as a consequence of multiple concussions. Attention is also turning to methods to assess concussion with questions surrounding the reliability in traditional methods of concussion assessment that include symptom observation and cognitive assessment. This chapter will discuss the neuroscience of sports-related concussion, reviewing the evidence from new and rigorous methods of concussion assessment, such as neuroimaging and electrophysiology, with a focus on transcranial magnetic stimulation, following acute concussive events through tolong-term manifestations of multiple concussions.

Étude des corrélats neurobiologiques des effets à long terme des commotions cérébrales liées au sport

L’âge, le génotype et les traumatismes crâniens (TCC) sont trois facteurs de risque majeurs du développement de la maladie d’Alzheimer (MA). Avec une accumulation d’évidences démontrant la persistance d’anomalies cérébrales suite aux plus légers des TCC, qui affichent d’ailleurs la plus haute incidence, il devient impératif de tester l’hypothèse selon laquelle même les commotions cérébrales puissent interagir avec l’âge et les gènes afin de précipiter la neurodégénération. Trente ex-athlètes de haut niveau (âge M = 60 ans), dont la moitié a subi des commotions cérébrales il y a plus de 30 ans, ont été évalués en neuropsychologie, en neuroimagerie multimodale ainsi qu’en génétique. De nombreuses mesures neuroanatomiques, dont l’expansion du volume des ventricules latéraux, se trouvent à corréler avec divers déficits cognitifs (mémoire différée et de reconnaissance) détectés chez les participants commotionnés. D’un intérêt particulier, certains de ces résultats sont modulés par le polymorphisme nucléotidique simple du gène Apolipoprotéine E. Ces résultats appuient l’hypothèse selon laquelle la commotion cérébrale chez de jeunes athlètes serait un facteur de risque de neurodégénération dans le vieillissement normal.

Using transcranial magnetic stimulation to quantify electrophysiological changes following concussive brain injury: a systematic review

Mild traumatic brain injury (mTBI) and sports concussion are a growing public health concern, with increasing demands for more rigorous methods to quantify changes in the brain post-injury. Electrophysiology, and in particular, transcranial magnetic stimulation (TMS), have been demonstrated to provide prognostic value in a range of neurological conditions; however, no review has quantified the efficacy of TMS in mTBI/concussion. In the present study, we present a systematic review and critical evaluation of the scientific literature from 1990 to 2014 that has used TMS to investigate corticomotor excitability responses at short-term (< 12 months), medium-term (1-5 years), and long-term (> 5 years) post-mTBI/concussion. Thirteen studies met the selection criteria, with six studies presenting short-term changes, five studies presenting medium-term changes, and two studies presenting long-term changes. Irrespective of time post-concussion, change in intracortical inhibition was the most reported observation. Other findings included increased stimulation threshold, and slowed neurological conduction time. Although currently limited, the data suggest that TMS has prognostic value in detecting neurophysiological changes post-mTBI/concussion.

Commotion cérébrale chez l'enfant et l'adolescent sportif [Concussion in children and adolescents during sports].

Concussion, a frequent injury in sports, is rarely evoked and often trivialized in children and teenagers. Knowledge of the diverse symptoms and signs to seek for is essential to an appropriate and secure management. The initial treatment relies on cognitive and physical rest followed by a progressive return to school and subsequently sport activities. The aim of this article is to review an injury whose prognosis is generally favourable, but whose rare complications can prove dramatic.

Knowledge about sports-related concussion: is the message getting through to coaches and trainers?

Aim The need for accurate diagnosis and appropriate return-to-play decisions following a concussion in sports has prompted the dissemination of guidelines to assist managing this condition. This study aimed to assess whether key messages within these guidelines are reflected in the knowledge of coaches and sports trainers involved in community sport. Methods An online knowledge survey was widely promoted across Australia in May–August 2012 targeting community Australian Football (AF) and Rugby League (RL) coaches and sports trainers. 260 AF coaches, 161 AF sports trainers, 267 RL coaches and 228 RL sports trainers completed the survey. Knowledge scores were constructed from Likert scales and compared across football codes and respondent groups. Results General concussion knowledge did not differ across codes but sports trainers had higher levels than did coaches. There were no significant differences in either concussion symptoms or concussion management knowledge across codes or team roles. Over 90% of respondents correctly identified five of the eight key signs or symptoms of concussion. Fewer than 50% recognised the increased risk of another concussion following an initial concussion. Most incorrectly believed or were uncertain that scans typically show damage to the brain after a concussion occurs. Fewer than 25% recognised, and >40% were uncertain that younger players typically take longer to recover from concussion than adults. Conclusions The key messages from published concussion management guidelines have not reached community sports coaches and sports trainers. This needs to be redressed to maximise the safety of all of those involved in community sport.

Implementation of concussion guidelines in community Australian Football and Rugby League– the experiences and challenges faced by coaches and sports trainers

Objectives

While guidelines outlining the appropriate management of sport-related concussion have been developed and adapted for use within community sport, it remains unknown how they are experienced by those responsible for implementing them.
Design

Longitudinal study.
Methods

111 coaches and sports trainers from community-level Australian Football and Rugby League teams completed pre- and post-season surveys assessing their attitudes towards using concussion guidelines. Participants also provided post-season feedback regarding their experiences in using the guidelines.
Results

71% of participants reported using the guidelines in the preceding season. Post-season attitude was related to pre-season attitude (p = 0.002), football code (p = 0.015), and team role (p = 0.045). An interaction between team role and guideline use (p = 0.012) was also found, with coaches who had used the guidelines, and sports trainers who had not, reporting more positive post-season attitudes towards using the concussion guidelines. Implementation challenges included disputing of decisions about return-to-play by players, parents, and coaches, and a perceived lack of time. Recommendations for improved guideline materials included using larger fonts and providing for witnessing of advice given to players.
Conclusions

This is the first study to examine the implementation of concussion guidelines in community sport. Training of coaches/sports trainers needs enhancement. In addition, new education should be developed for parents/players about the importance of the return-to-play advice given to them by those who follow these guidelines. Information provided by those who attempted to use the guidelines will assist the refinement of implementation and dissemination processes around concussion guidelines across sports.

Translating guidelines for the diagnosis and management of sports-related concussion into practice

Sports injuries are a significant clinical and public
health concern. There is a growing call to improve the translation of available evidence-based and expert- informed sports injury prevention interventions into sustained use in practice by physicians and others (eg, athletic trainers, coaches, and parents) who care for injured athletes. This article provides a brief overview of the current sport injury prevention implementation literature before focusing specifically on the translation of guidelines (including consensus and position statements) developed to assist physicians and others diagnose and manage athletes with sport-related concussion and the associated return-to-play decisions. The outcomes of more than 20 published studies indicate that physician, athletic trainer, coach, parent,
and athlete knowledge, use of, and compliance with sport-related concussion guidelines are limited. More concerted, coordinated, and theory-informed efforts are required to facilitate the widespread dissemination, translation, and implementation of such guidelines. An example is provided of how implementation drivers could be used to inform the development of a comprehensive, multilevel implementation strategy targeting the individual, organizational, and system-level changes necessary to support the translation of available sport-related concussion guidelines in both the clinical and sports settings.

Concussion and Brain Injury in Contact Sport: Legal Implications

A concussed participant leaving the field of play is one of the most worrying sights in sport. It is also one that might have serious legal implications for sports governing bodies. Over the past number of years, a major class action suit has rumbled through the US courts as taken against that country's biggest professional sport, the National Football League. The NFL is at present attempting to settle the lawsuit from more than 4,500 retired players who claim that the NFL knew for decades about the chronic health risks associated with cumulative concussions in American football but failed to warn players or take preventative steps. Testimony from retired NFL players has revealed stories of chronic headaches, Alzheimer-like forgetfulness, altered personalities and sometimes a downward spiral into depression, violence and suicide. Medical research is suggesting that professional American football players are three times more likely to die as a result of certain neurodegenerative diseases than the general population. This paper notes that the concerns about concussion are not confined to the NFL and extend to contact sport more widely and notably rugby union. This paper also assesses the reaction of leading sports governing bodies globally to the recorded medical risks and accompanying legal vulnerabilities.

Extreme sports as a facilitator of ecocentricity and positive life changes

Extreme sports and extreme sports participants have been most commonly explored from a negative perspective, for example the 'need to take unnecessary risks'. This study reports on findings that indicate a more positive experience. A phenomenological method was used via unstructured interviews with 15 extreme sports participants and other first hand accounts. The extreme sports included B.A.S.E. jumping, big wave surfing, extreme skiing, waterfall kayaking, extreme mountaineering and solo rope-free climbing. Results indicate that participating in activities that involve a real chance of death, fear and the realisation that nature in its extreme is far greater and more powerful than humanity triggers positive life changes, and an eco-centric standpoint.