- Title
- Concussion in professional rugby league
- Creator
- Gardner, Andrew J.
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2015
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Background: Rugby League is a popular full-contact sport played internationally by 18 full-member test nations of the Rugby League International Federations (RLIF), 21 RLIF affiliate-members, and approximately 32 other unaffiliated nations. The most popular elite, professional, domestic leagues are played in Australia and the United Kingdom. Rugby league game play involves numerous collisions and tackles, and it carries an inherent risk for injury including head trauma. Despite the increased interest in sport-related concussion in recent years, only a limited number of studies have been conducted in rugby league players on this topic, with the large majority of publications only addressing the incidence of concussion as a secondary outcome measure within sports-specific injury focused studies. Additionally, there are currently no published papers on the potential long-term consequences of sport-related concussion in retired professional rugby league players. Aim/Purpose: This thesis addresses some of the issues related to the identification and acute management of sport-related concussion in professional rugby league players. It also examines the potential long-term consequence of concussion in retired professional rugby league players. One of the overall aims of this thesis was to conduct a systematic review of the literature examining both, (i) concussion in rugby league; and (ii) the use of magnetic resonance spectroscopy in sport-related concussion. These systematic review papers set the scene for the main aims of this thesis, which were to address the identified gaps in the literature, first by identifying the factors associated with concussion in rugby league at the professional level via systematic video analysis of the injury. The purpose of this first study was to described player and injury characteristics, situational factors, concussion signs, and return to play. A secondly aim was to examine the potential long-term consequences of a history of multiple concussions in retired professional rugby league players. The purpose of this second study was to examine the brain neurometabolite concentrations and the cognitive profiles of retired rugby league players who had a history of numerous self-reported concussions. Methods: Paper 1: This systematic review involved the retrieval of eligible studies pertaining to concussion in rugby league players. Numerous online databases were searched for publication in English from 1900 up to June 2013 using the key search terms: rugby league, league, football; in combination with injury terms: athletic injuries, concussion, sports concussion, sports related concussion, brain concussion, brain injury, brain injuries, mild traumatic brain injury, mTBI, traumatic brain injury, TBI, craniocerebral trauma, head injury, and brain damage. Articles were regarded as relevant and warranting inclusion if they were experimental studies examining concussed rugby league players. Studies were included whether they were conducted with acute or long-term concussed athletes (i.e., there were no restrictions placed on time elapsed since injury). Paper 2: All National Rugby League clubs were invited to participate in this video analysis study of concussion, three agreed to participate. All players medically diagnosed with a concussion by an experienced team physician from the three participating clubs were included in the study. The digital video footage of games in which each concussion was diagnosed was reviewed. Descriptions pertaining to player’s demographic information (i.e., age, height, weight, playing position, and game performance statistics) and return to match play were also recorded. Two raters independently viewed the digital records of events leading to concussion. Relevant variables were pre-determined and data were independently recorded by both raters. In order to reach consensus, all discrepancies between raters resulted in a review of the footage together and a discussion regarding the recorded data. Under circumstances where consensus was not reached, a third rater was to be consulted to make the final determination, however this was not required. Paper 3: Each use of the ‘Concussion Interchange Rule’ (‘CIR’) during the 2014 National Rugby League season was included in the study. There was no video analysis conducted on any event that was not logged and assessed by club medical staff. Access to video footage of the incident was attained through the National Rugby League’s Digital Press Pass subscription. All uses of the CIR were independently reviewed by the first author and at least one other author. Two authors were blinded to the study hypotheses but the first author was not blinded. The three raters determined whether any of six signs (loss of consciousness, loss of muscle tone, seizures, clutching of the head, unsteadiness of gait, or possible impairment in cognition or awareness as evidenced by a blank or vacant stare) were present, absent, or indeterminable based on the available footage of the incident for every case. When there was disagreement between the two primary raters (who rated all incidents), both raters reviewed and discussed those cases in an effort to reach consensus. In the cases where consensus could not be achieved, ratings from a third rater were used. Paper 4: This systematic review involved the retrieval of eligible studies pertaining to magnetic resonance spectroscopy and concussion in athletes. Numerous online databases were searched for publication in English up to February 2013 using the key search terms: magnetic resonance spectroscopy, nuclear magnetic resonance spectroscopy, neurospectroscopy, spectroscopy, two-dimensional nuclear magnetic resonance spectroscopy, correlation spectroscopy, J-spectroscopy, exchange spectroscopy, nuclear overhauser effect spectroscopy, NMR, MRS, COSY, EXSY, NOESY, 2D NMR, craniocerebral trauma, mild traumatic brain injury, mTBI, traumatic brain injury, brain concussion, concussion, brain damage, sport, athletic, and athlete. Articles were regarded as relevant, and warranting inclusion in the review if they were experimental studies using MRS to determine the presence (or absence) of pathophysiology in concussed athletic samples. Studies were included whether they were conducted acutely or post-acutely (i.e., there were no restrictions placed on time since injury) and whether or not they also used other outcome measures (e.g., conventional MRI, CT, symptom checklists, balance testing, or neuropsychological testing). All retrieved articles were independently assessed for quality using a standardized quality assessment checklist. Paper 5: Retired professional rugby league players (n=13) were recruited through communication with the club alumni. Exclusion criteria included any medical history of neurosurgery, or any history of a brain tumor requiring radiation treatment, or claustrophobia. Healthy community control subjects similar in age and education were recruited through a research participant registry established by a medical research institute. All participants completed a clinical interview and neurocognitive testing. The total interview and testing time was approximately 135 minutes. The MRS data was collected during a separate, single testing session on all participants as one component of a multiparametric neuroimaging study. The imaging time for the MRS component of the study was approximately 25 minutes; the whole multiparametric acquisition time was approximately 65 minutes. An overall test battery mean was computed by summing and averaging the normative scores (expressed in T score units with a mean of 50 and a SD of 10). Conventional Imaging was performed on a 3 T Siemens Skyra scanner with a 20-channel head coil. MRS voxels were placed in posterior cingulate grey matter (GM) and parietal white matter (WM). Concentrations of glutamate (Glu), glutathione (GSH), myo-inositol (mI), N-acetylaspartate (NAA), total choline (tCho), creatine+phosphocreatine (tCr), and glutamate+glutamine (Glx) were quantified using LCModel and water scaling. Results: [more detail in thesis abstract] Conclusion: Rugby league is a contact sport with high incidence of concussions, which leads to participants being exposed to numerous concussions during their careers. The current series of studies adds enormously to rugby league concussion literature, which had previously been quite limited, as identified in the systematic review of the rugby league concussion literature (Chapter 2). The current series of studies characterised concussion at the professional level in current rugby league players; identifying antecedent events and risk factors, together with return to play management and decision-making. In addition to investigating current players, this series of studies also investigated cognition and neurometabolites in retired professional rugby league players. While the current series of studies identifies concussion as a common risk factor for participation in rugby league, the potential long-term consequences for rugby league players with a history of numerous concussions remains a topic requiring further investigation. In the small sample of retired players included in Study 3, not one player expressed significant concerns regarding their cognition and on neuropsychological assessment none of the retired rugby league players performed significantly below their estimated pre-morbid level of intellectual function. So for all intents and purposes the investigation was conducted in ‘asymptomatic’ retired rugby league players, however there were significant neurometabolic differences observed between groups on magnetic resonance spectroscopy. The clinical relevance of this finding also requires further investigation, but it may suggest that MRS is sensitive to possible pre-clinical symptomology that other methodologies (i.e., neuropsychological testing) are not sufficiently sensitive to detect.
- Subject
- sport-related concussion; rugby league; neurospectroscopy; video analysis; retired athletes; neuroimaging; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1310314
- Identifier
- uon:22019
- Rights
- Copyright 2015 Andrew J. Gardner
- Language
- eng
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