A Historical Perspective on Sports Concussion: Where We Have Been and Where We Are Going

Context Matters: Extra-Personal Factors Underlying Concussion Reporting in University Athletes

Gaps remain in our understanding of which factors contribute to concussion disclosure and how they contribute to this process, thereby limiting our ability to improve disclosure. This study aimed to characterize the most relevant extra-personal determinants of SC disclosure and to describe their influence on the disclosure process. To that aim, the first author conducted substantive qualitative interviews with nine university student-athletes and analyzed their content via constant comparative analysis (guided by Straussian grounded theory). Eleven (11) extra-personal concepts influencing concussion reporting were identified and described across two categories: Contextual Incentives and Socio-Cultural Pressures. These findings suggest that each identified concept can individually shape the context around the injury, creating either higher-stakes conditions that deter disclosure or lower-stakes conditions that encourage it. Further, the results posit that these concepts interact and collectively influence athletes' decision-making process by modulating the perceived stakes of disclosing a concussion. If these findings hold true in more diverse populations and contexts, they suggest that adapting concussion prevention efforts to consider these contextual variables could improve SC disclosure. This study also highlights the benefits of using qualitative methods in the investigation of concussion reporting.

Long-term effects of concussion on attention, sensory gating and motor learning

The current work aimed to understand the behavioral manifestations that result from disruptions to the selective facilitation of task-relevant sensory information at early cortical processing stages in those with a history of concussion. A total of 40 participants were recruited to participate in this study, with 25 in the concussion history group (Hx) and 15 in the control group (No-Hx). Somatosensory-evoked potentials (SEPs) were elicited via median nerve stimulation while subjects performed a task that manipulated their focus of attention toward or away from proprioceptive cues. Participants also completed an implicit motor sequence learning task relying solely on proprioceptive cues, as well as a visual attentional blink (AB) task to understand the effect of concussion on rapid shifts in attention. The Hx SEP data replicated past work showing an absence of relevancy-based facilitation at early cortical processing stages (N20-P27) that emerged at later processing stages. Our Hx showed evidence of relevancy-based facilitation at either the P50-N70 or the N70-P100. Performance on the learning task was not significantly different between the Hx and No-Hx. Performance on the AB task revealed greater AB magnitude in the Hx compared to the No-Hx. Collectively, these results suggest a compensatory strategy in the Hx that enables them to learn to the same degree as controls. However, when the attentional system is taxed with high temporal demands there are decrements in performance. These results are of particular importance given that these individuals are at an increased risk of sustaining subsequent concussions, and musculoskeletal injuries.

Sports Related Concussion

Sports-related concussions (SRC) have been a topic of interest for decades and are a prevalent risk of sports participation. The definition of SRC continues to evolve but includes a plausible mechanism and associated symptoms of injury. Rates of concussion vary among sports, and many sports have adopted rule changes to limit this risk for its athletes. There has been a considerable effort to prevent the occurrence of SRC, as well as a focus on safe return to learn and sport alike. There is growing concern about the ramifications of concussions, which will continue to warrant further investigation.

Disrupted resting-state functional connectivity and network topology in mild traumatic brain injury: an arterial spin labelling study

Mild traumatic brain injury can cause different degrees of cognitive impairment and abnormal brain structure and functional connectivity, but there is still a lack of research on the functional connectivity and topological organization of cerebral blood flow fluctuations. This study explored the cerebral blood flow, functional connectivity and topological organization of the cerebral blood flow network in acute mild traumatic brain injury patients. In total, 48 mild traumatic brain injury patients and 46 well-matched healthy controls underwent resting-state arterial spin labelling perfusion MRI and neuropsychological assessments. The functional connectivity and topological organization of the cerebral blood flow network were analysed. Then, the correlation between the changes in cerebral blood flow network characteristics and cognitive function was explored. Acute mild traumatic brain injury patients showed decreased cerebral blood flow in the right insula and increased cerebral blood flow in the right inferior temporal gyrus and left superior temporal gyrus. Abnormal cerebral blood flow network connection patterns mainly occur in sensorimotor network, default mode network, cingulo-opercular network and occipital network-related regions. Furthermore, mild traumatic brain injury disrupted the topological organization of the whole brain, which manifested as (i) reduced global efficiency; (ii) abnormal degree centrality, betweenness centrality, nodal clustering coefficient and nodal efficiency; and (iii) decreased intermodular connectivity between the occipital network and sensorimotor network. Finally, the change in network topology was correlated with the cognitive score of the mild traumatic brain injury. This study provided evidence of abnormal functional connectivity and network topology based on cerebral blood flow in acute mild traumatic brain injury patients, revealing their potential use as early markers for mild traumatic brain injury, which may contribute to both disease diagnosis and assessment.

Physical Activity Following Sport-Related Concussion in Adolescents: A Systematic Review

OBJECTIVE

To evaluate the evidence related to how physical activity (PA) affects recovery following a sport-related concussion (SRC) in adolescents.

DESIGN

Systematic review Data Source: PUBMED, MEDLINE, and SPORTDiscus Eligibility criteria for selecting study:(1) original research article (e.g., randomized controlled trials (RCT), quasi-experimental designs, cohort, case-control studies), (2) 66% or greater of the sample has to have a SRC diagnosed by a clinician, (4) human research, (5) evaluate the effect of a SRC on PA in adolescents only (<18 years). Participants were seen within 1-2 weeks post-SRC for acute studies and 4 weeks post-SRC for studies focused on prolonged recoveries.

RESULTS

Twenty-two studies met the inclusion criteria (i.e., 8 regarding PA (PA-daily aerobic activity including light-moderate intensities), 8 evaluating active rehabilitation/exercise programs (20 minutes of daily aerobic exercise below symptom threshold), 6 examining a single bout of exertion). The methodological quality of the literature was assessed using the Downs and Black risk of bias (ROB) checklist. The ROB scores ranged from 7-24, with only two RCTs included. Studies demonstrated single bouts of exertion testing were safe and feasible. Daily PA or active rehabilitation/exercise programs led to a reduction in symptoms present and a decrease in number of days to medical clearance.

CONCLUSION

Following a brief period of rest (24-48 hours), individuals can gradually and safely return to PA below their physical symptom exacerbation thresholds. Further research is warranted to delineate how to optimize the timing, intensity, duration, and modality of PA impacts symptom resolution and physiological recovery following SRC.

Top-100 Most-Cited Sports-Related Concussion Articles Focus on Symptomatology, Epidemiology, and Demographics

Purpose

To analyze the top-100 cited articles on sports-related concussions together with a bibliometric analysis to determine citations by year, level of evidence, study design, and several other factors related to the top referenced articles in sports concussions.

Methods

The Clarivate Analytics Web of Knowledge database was used to gather data using Boolean queries to capture all possible iterations of sports-related concussion research. Articles were organized in descending order based on the number of citations and included or excluded based on relevance to concussion. Collected information included author name, publication year, country of origin, journal name, article type, study focus, and the level of evidence.

Results

The top-100 articles were cited 31,197 times with an average of 312.0 citations per publication. More than one half were published in 2006 or later (52). Cohort studies and descriptive articles were the most prevalent study types (22 each). Studies with Level V evidence were the most common (33). The most common areas of study were symptomatology (short term, long term) with 17 articles, followed by epidemiology/demographics with 16 articles. The least common area of study was concussion prevention (2 articles), followed by management/treatment, diagnostics (labs, imaging) with 4 articles each.

Conclusions

We identified the most influential studies in sports-related concussion based on number of citations and citation density. A majority of these articles were published in the United States after 2006 and are most commonly cohort studies (Level IV evidence) and descriptive articles (Level V evidence). Current research focuses most heavily on the symptomatology and epidemiology/demographics of sports concussion.

Clinical Relevance

This study serves to identify the most influential articles in sports-related concussion and identify research topics with general deficiencies within the field of sports-related concussion research.

Noninvasive magnetic resonance imaging techniques in mild traumatic brain injury research and diagnosis

Mild traumatic brain injury (mTBI), frequently referred to as concussion, is one of the most common neurological disorders. The underlying neural mechanisms of functional disturbances in the brains of concussed individuals remain elusive. Novel forms of brain imaging have been developed to assess patients postconcussion, including functional magnetic resonance imaging (fMRI), susceptibility-weighted imaging (SWI), diffusion MRI (dMRI), and perfusion MRI [arterial spin labeling (ASL)], but results have been mixed with a more common utilization in the research environment and a slower integration into the clinical setting. In this review, the benefits and drawbacks of the methods are described: fMRI is an effective method in the diagnosis of concussion but it is expensive and time-consuming making it difficult for regular use in everyday practice; SWI allows detection of microhemorrhages in acute and chronic phases of concussion; dMRI is primarily used for the detection of white matter abnormalities, especially axonal injury, specific for mTBI; and ASL is an alternative to the BOLD method with its ability to track cerebral blood flow alterations. Thus, the absence of a universal diagnostic neuroimaging method suggests a need for the adoption of a multimodal approach to the neuroimaging of mTBI. Taken together, these methods, with their underlying functional and structural features, can contribute from different angles to a deeper understanding of mTBI mechanisms such that a comprehensive diagnosis of mTBI becomes feasible for the clinician.

An insight into the world of sports dentistry

Dental trauma in the field of sports is the major linking channel between sports and dentistry. Sports dentistry is the branch of sports medicine that deals with the prevention of oral or facial athletic injuries, oral diseases and manifestations. Sports dentistry is also related to mild traumatic brain injuries during games and erosive lesions due to continuous intake of highly acidic sports and energy drinks. Stress among sportsperson has also been depicted to impact their athletic performance leading athletes to the intake of drugs. Smokeless tobacco consumption and sponsorship is also found among athletes. Therefore, it is emphasized the need for a "team dentist," initiating from high schools to professional teams. The sports or "team dentist" assists athletes in the effective prevention, treatment, and diagnosis of various types of oral injuries. Sport-related orofacial injuries can be prevented by wearing primary protective devices such as properly fitting helmets, face masks and/or mouth guards. They can also enlighten athletes about the benefits of practicing yoga, as it reduces stress and improves performance. Hence, the dentist can perform an imperative role in informing parents, athletes, coaches and patients about the importance of preventing orofacial injuries in sports.

Evidence based management of sports related concussion

Sports related concussion (SRC) is a common condition evaluated by healthcare professionals. In an article entitled "Return to Play After Concussion: Clinical Guidelines for Young Athletes" published in the December 2019 issue of the Journal of the American Osteopathic Association, guidelines for the management of SRC were presented to assist healthcare professionals in the management of patients with SRC. However, much of the information presented in that article is contradicted by current expert recommendations and evidence based practice guidelines. The management of SRC has evolved to a nuanced, domain driven diagnosis requiring a multidisciplinary treatment team and a customized management plan for each patient to ensure competent treatment of patients with SRC. As such, this Commentary summarizes current recommendations for diagnosis and management of SRC.

Wirksamkeit manualtherapeutischer Techniken in Kombination mit vestibulärer Rehabilitation nach sportbedingten Gehirnerschütterungen – Eine systematische Übersichtsarbeit randomisiert kontrollierter Studien

Hintergrund Die Rehabilitation nach leichter, sportbedingter Gehirnerschütterung erfordert eine komplexe Behandlung unter Berücksichtigung der muskuloskelettalen, insbesondere zervikogenen, und vestibulären Beteiligung. Das empfohlene Rehabilitationskonzept der vollständigen Ruhe bis zur Beschwerdefreiheit wird inzwischen neu bewertet. Aktuelle Studien deuten auf positive Auswirkungen einer frühen Mobilisierung und multimodaler Physiotherapie hin. Der medizinische Nutzen ausgewählter manualtherapeutischer Techniken wird in mehreren klinischen Studien untersucht. Bisher konnten jedoch keine eindeutigen Empfehlungen für manualtherapeutische Techniken nach einer Gehirnerschütterung ausgesprochen werden.

Ziel Analyse und Zusammenfassung vorhandener randomisiert kontrollierter Studien (RCTs) zur Untersuchung der Wirksamkeit manualtherapeutischer Techniken in Kombination mit vestibulärer Rehabilitation auf Symptomfreiheit und Wiedererlangung der sportlichen Belastbarkeit bei Patienten nach sportbedingten Gehirnerschütterungen.

Methode Systematische Recherche in den Datenbanken ClinicalTrials.gov, WHO-ICTRP, EBSCO, PubMed und PEDro mit den Suchbegriffen concussion, physiotherapy, manual therapy und mild traumatic brain injury. Eingeschlossen wurden RCTs zur Untersuchung manualtherapeutischer Techniken nach sportbedingten Gehirnerschütterungen oder milden Formen eines Schädelhirntraumas. Die Bewertung der methodischen Qualität erfolgte Anhand der PEDro-Skala.

Ergebnisse Publikationen zu 2 RCTs mit guter und moderater methodischer Qualität (PEDro-Skala: 7–8/10 Punkten) sowie eine Folgestudie wurden inkludiert. Als primärer Outcome-Parameter wurde in allen Studien der Zeitraum der ärztlichen Freigabe zur Rückkehr zum Sport angegeben. Sekundäre Outcome-Parameter bezogen sich auf Symptomfreiheit, Postconcussion Scale, Numeric Pain Rating Scale, Balance Confidence Scale, Dizziness-Handicap-Index, Sport Concussion Assessment Tool 2 und Joint-Position-Error-Test. Die Ergebnisse aller inkludierten Studien ergaben signifikante Unterschiede zugunsten der Interventionsgruppen. Die eingeschlossenen klinischen Studien waren jedoch in Bezug auf Design, Methodik und Auswahl der Techniken heterogen, was einen direkten Vergleich erschwerte.

Schlussfolgerung Abgeschlossene klinische Studien deuten darauf hin, dass manualtherapeutische Techniken als Teil eines multimodalen Rehabilitationsprogramms nach Gehirnerschütterungen und leichten Schädelhirntraumata von Nutzen sein können. Aufgrund der geringen Anzahl an RCTs und deren heterogenen Studiendesigns ist eine Bewertung der Wirksamkeit spezifischer manualtherapeutischer Techniken derzeit nicht möglich. Weitere hochwertige Studien sind erforderlich.

Video Analysis of Concussion Exposures in a National Collegiate Athletic Association Division I Football Team

Background:

Research into improving player safety of sport-related concussion (SRC) in American football has been an ongoing endeavor. In an attempt to better understand the incidence of SRCs in American football, research has focused on the characteristics of SRC during gameplay. Determining SRC specifics and assessing them quantitatively can help identify high-risk scenarios and predict exposure risk.

Purpose:

To identify and assess the incidence of SRCs in a National Collegiate Athletic Association football team by comparing field location, player positions, collision partners, and player cues.

Study Design:

Descriptive epidemiology study.

Methods:

We used physician sideline reports of diagnosed concussions from a Division I football team from September 2010 to December 2018. Game videos were analyzed to identify the field location where the SRC occurred, collision partner, and player behavior postconcussion. The incidence of in-game SRCs by position was also assessed. We used the “words of estimative probability” model to categorize each concussion as certain, almost certain, probable, or even on the basis of our confidence in identifying them using game film.

Results:

This study examined 44 SRCs that occurred over 9 seasons. The SRC incidence was significantly higher in the middle defense (5-20 yards from the line of scrimmage) compared with all other field locations (relative risk, 2.46; 95% CI, 1.14-5.29; P < .05). In-game collision partners were most commonly defensive backs. The most common player cue was a hand to helmet/face mask. The positions with the highest SRC incidence by athlete-exposure, game position, and position play belonged to the defensive backs, wide receivers, and running backs.

Conclusion:

The middle defense had a significantly higher incidence of SRCs than all other field locations. We pose a new method to categorize concussions during video analysis by using words of estimative probability. Knowledge of SRC gameplay characteristics can potentially guide the medical staff and medical observer to better identify them.

A review of concussion diagnosis and management in Australian professional sporting codes

Objectives: The recognition and management of concussion has become a major health concern across all sports. Despite recent attention, concussion assessment and return-to-play protocols appear to be highly variable between leading professional sporting bodies across Australia. Without readily available guidelines, players at all levels may be at risk of suboptimal management following in-game trauma. The purpose of this study was to explore the publicly available concussion guidelines of the major Australian sporting codes with an aim to identify potential opportunities to develop a national sporting consensus.Methods: Internet sites of the major sporting organizations within Australia were accessed between June 2018 to July 2018. Sites were reviewed for information pertaining to an available concussion protocol or guidelines including; concussion definition, player education documentation, requirement of baseline testing, standard concussion diagnostic measures, use of sideline testing and removal from play guidelines, return-to-play, minimum return-to-play intervals and the implementation of external evaluation of potential concussion cases.Results: Twelve sites were visited. There was consensus between many of the sporting organizations in terms of concussion definition, removal of play and sideline testing protocols. A step-wise return-to-play protocol was prevalent across most sports. A number of sporting sites however did not have readily available information.Conclusions: There is notable room for the development of concussion guidelines in Australian sport. Researchers and sporting organizations need to continuously amend current protocols to ensure this reflects best evidence-based practice.

Multimodal Imaging of Retired Professional Contact Sport Athletes Does Not Provide Evidence of Structural and Functional Brain Damage

BACKGROUND

Long-term consequences of playing professional football and hockey on brain function and structural neuronal integrity are unknown.

OBJECTIVES

To investigate multimodal metabolic and structural brain magnetic resonance imaging (MRI) differences in retired professional contact sport athletes compared with noncontact sport athletes.

METHODS

Twenty-one male contact sport athletes and 21 age-matched noncontact sport athletes were scanned on a 3 tesla (3T) MRI using a multimodal imaging approach. The MRI outcomes included presence, number, and volume of focal white matter signal abnormalities, volumes of global and regional tissue-specific brain structures, diffusion-tensor imaging tract-based spatial statistics measures of mean diffusivity and fractional anisotropy, quantitative susceptibility mapping of deep gray matter, presence, number, and volume of cerebral microbleeds, MR spectroscopy N-acetyl-aspartate, glutamate, and glutamine concentrations relative to creatine and phosphor creatine of the corpus callosum, and perfusion-weighted imaging mean transit time, cerebral blood flow, and cerebral blood volume outcomes. Subjects were also classified as having mild cognitive impairment.

RESULTS

No significant differences were found for structural or functional MRI measures between contact sport athletes and noncontact sport athletes.

CONCLUSIONS

This multimodal imaging study did not show any microstructural, metabolic brain tissue injury differences in retired contact versus non-contact sport athletes.

Pathophysiology of Concussion

Although concussion has been a subject of interest for centuries, this condition remains poorly understood. The mechanistic underpinnings and accepted definition of concussion remain elusive. To make sense of these issues, this article presents a brief history of concussion studies, detailing the evolution of motivations and experimental conclusions over time. Interest in concussion as a subject of scientific inquiry has increased with growing concern about the long-term consequences of mild traumatic brain injury (TBI). Although concussion is often associated with mild TBI, these conditions-the former a neurological syndrome, the latter a neurological event-are distinct, both mechanistically and pathobiologically. Modern research primarily focuses on the study of the biomechanics, pathophysiology, potential biomarkers and neuroimaging to distinguish concussion from mild TBI. In addition, mild TBI and concussion outcomes are influenced by age, sex, and genetic differences in people. With converging experimental objectives and methodologies, future concussion research has the potential to improve clinical assessment, treatment, and preventative measures.

Managing Sports-related Concussions From Time of Injury Through Return to Play

Sports-related concussions continue to generate widespread interest. A concussion is a complex pathophysiologic process, with or without loss of consciousness, that results in a disturbance of brain function. Risk factors include age <18 years, female sex, and history of a previous concussion. A sideline physical examination with standardized assessment tools can assist diagnosis. Management for suspected concussion begins with immediate removal from play and requires clinical follow-up. Symptoms are usually self-limited and resolve within 2 to 3 weeks. Initial treatment consists of a reduction in cognitive activity and physical rest. A stepwise return-to-play protocol, taking into consideration state laws, with a gradual increase in activity until the athlete is able to perform full activity without symptoms should be followed. Neuropsychologic testing may be used as a tool in management. For prolonged concussion, physical rehabilitation or medications for headaches, mood, or sleep disturbance may be required. Education, rule changes, and equipment improvements may assist in prevention. The long-term consequences of concussions are not fully understood and merit additional research.

Pilot single-centre cross-sectional study to determine emergency physicians' knowledge and management of sports concussion: an experience from Singapore

INTRODUCTION

Sports concussion remains challenging to manage despite changes to policy and practice since the 2012 International Consensus Conference on Concussion in Sport. Emergency physicians (EPs) are usually the first line of medical care for athletes in amateur and youth collision sports. This single-centre cross-sectional study aimed to establish EPs' understanding and management of concussion in Singapore.

METHODS

An anonymised, 17-item online questionnaire was sent to EPs requesting for information on their clinical experience, training, exposure to concussion cases in the emergency department (ED) and assessed knowledge of the condition.

RESULTS

Out of 65 EPs, 52 (80%) responded, 25 (48.1%) of whom were medical officers. Over 90% had not received formal training in concussion management, and 73.1% regularly assessed concussion. 40 (76.9%) EPs recognised that loss of consciousness was not essential for diagnosis and only 24 (46.2%) knew the most common symptom. 26 (50.0%) incorrectly reported that they would perform brain imaging. Among those who indicated onward referral, 29 (55.8%) would refer concussed patients to neurosurgery. There were no significant differences between clinical grade or training in concussion and positive responses for definition, imaging modality or most common symptom of concussion.

CONCLUSION

Concussion is a common presentation to EDs in Singapore. However, understanding of the condition, its clinical diagnosis, investigation and onward management is limited. Although EPs reported training in concussion, it is likely to be insufficient. Commencing relevant education programmes for undergraduate and postgraduate medical students may enable progressive acquisition of knowledge and thereby improve patient management in the future.

Moving concussion care to the next level: The emergence and role of concussion clinics in the UK

Concussion is a worldwide issue in sports medicine at present, and in recent years has evolved into a major consideration for sports in the United Kingdom (UK). Governing bodies, sports clinicians, and indeed athletes themselves are dealing with the implications that this injury brings. In parallel with this, innovative means of managing this condition are emerging. The creation of specialized concussion clinics (which mirror those present in the United States and Canada) is one means of enhancing concussion care in the UK. In this chapter, the emergence of concussion clinics in the UK will be discussed. The specific roles of the multidisciplinary teams working in these clinics will be outlined (including the disciplines of sports medicine, radiology, neurology, physiotherapy, and psychology/psychiatry), and the approaches used in the management of concussion in this setting will be explored. Future recommendations for the growth and development of clinic-based concussion care in the UK will also be discussed.

White matter changes in patients with mild traumatic brain injury: MRI perspective

This review focuses on white matter (WM) changes in mild traumatic brain injury (mTBI) as assessed by multimodal MRI. All the peer reviewed publications on WM changes in mTBI from January 2011 through September 2016 are included in this review. This review is organized as follows: introduction to mTBI, the basics of multimodal MRI techniques that are potentially useful for probing the WM integrity, summary and critical evaluation of the published literature on the application of multimodal MRI techniques to assess the changes of WM in mTBI, and correlation of MRI measures with behavioral deficits. The MRI-pathology correlation studies based on preclinical models of mTBI are also reviewed. Finally, the author's perspective of future research directions is described.