Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport-Amsterdam, October 2022.

For over two decades, the Concussion in Sport Group has held meetings and developed five international statements on concussion in sport. This 6th statement summarises the processes and outcomes of the 6th International Conference on Concussion in Sport held in Amsterdam on 27-30 October 2022 and should be read in conjunction with the (1) methodology paper that outlines the consensus process in detail and (2) 10 systematic reviews that informed the conference outcomes. Over 3½ years, author groups conducted systematic reviews of predetermined priority topics relevant to concussion in sport. The format of the conference, expert panel meetings and workshops to revise or develop new clinical assessment tools, as described in the methodology paper, evolved from previous consensus meetings with several new components. Apart from this consensus statement, the conference process yielded revised tools including the Concussion Recognition Tool-6 (CRT6) and Sport Concussion Assessment Tool-6 (SCAT6, Child SCAT6), as well as a new tool, the Sport Concussion Office Assessment Tool-6 (SCOAT6, Child SCOAT6). This consensus process also integrated new features including a focus on the para athlete, the athlete's perspective, concussion-specific medical ethics and matters related to both athlete retirement and the potential long-term effects of SRC, including neurodegenerative disease. This statement summarises evidence-informed principles of concussion prevention, assessment and management, and emphasises those areas requiring more research.

Prospective longitudinal investigation shows correlation of event-related potential to mild traumatic brain injury in adolescents.

STUDY DESIGN: Prospective longitudinal cohort study. BACKGROUND: Adolescent athletes may be more susceptible to the long-term effects of mild traumatic brain injury (mTBI). A diagnostic and prognostic neuromarker may optimize management and return-to-activity decision-making in athletes who experience mTBI. OBJECTIVE: Measure an event-related potential (ERP) component captured with electroencephalography (EEG), called processing negativity (PN), at baseline and post-injury in adolescents who suffered mTBI and determine their longitudinal response relative to healthy controls. METHODS: Thirty adolescents had EEG recorded during an auditory oddball task at a pre-mTBI baseline session and subsequent post-mTBI sessions. Longitudinal EEG data from patients and healthy controls (n= 77) were obtained from up to four sessions in total and processed using Brain Network Analysis algorithms. RESULTS: The average PN amplitude in healthy controls significantly decreased over sessions 2 and 3; however, it remained steady in the mTBI group's 2nd (post-mTBI) session and decreased only in sessions 3 and 4. Pre- to post-mTBI amplitude changes correlated with the time interval between sessions. CONCLUSION: These results demonstrate that PN amplitude changes may be associated with mTBI exposure and subsequent recovery in adolescent athletes. Further study of PN may lead to it becoming a neuromarker for mTBI prognosis and return-to-activity decision-making in adolescents.

What are the critical elements of sideline screening that can be used to establish the diagnosis of concussion? A systematic review.

BACKGROUND: Sideline detection is the first and most significant step in recognising a potential concussion and removing an athlete from harm. This systematic review aims to evaluate the critical elements aiding sideline recognition of potential concussions including screening tools, technologies and integrated assessment protocols. DATA SOURCES: Bibliographic databases, grey literature repositories and relevant websites were searched from 1 January 2000 to 30 September 2016. A total of 3562 articles were identified. STUDY SELECTION: Original research studies evaluating a sideline tool, technology or protocol for sports-related concussion were eligible, of which 27 studies were included. DATA EXTRACTION: A standardised form was used to record information. The QUADAS-2 and Newcastle-Ottawa tools were used to rate risk of bias. Strength of evidence was assessed using the Grades of Recommendation, Assessment, Development and Evaluation Working Group system. DATA SYNTHESIS: Studies assessing symptoms, the King-Devick test and multimodal assessments reported high sensitivity and specificity. Evaluations of balance and cognitive tests described lower sensitivity but higher specificity. However, these studies were at high risk of bias and the overall strength of evidence examining sideline screening tools was very low. A strong body of evidence demonstrated that head impact sensors did not provide useful sideline concussion information. Low-strength evidence suggested a multimodal, multitime-based concussion evaluation process incorporating video review was important in the recognition of significant head impact events and delayed onset concussion. CONCLUSION: In the absence of definitive evidence confirming the diagnostic accuracy of sideline screening tests, consensus-derived multimodal assessment tools, such as the Sports Concussion Assessment Tool, are recommended. Sideline video review may improve recognition and removal from play of athletes who have sustained significant head impact events. Current evidence does not support the use of impact sensor systems for real-time concussion identification.

The Child Sport Concussion Assessment Tool 5th Edition (Child SCAT5): Background and rationale.

This article presents the Child Sport Concussion Assessment Tool 5th Edition (Child SCAT5). The Sport Concussion Assessment Tool was introduced in 2004, following the 2nd International Conference on Concussion in Sport in Prague, Czech Republic. Following the 4th International Consensus Conference, held in Zurich, Switzerland, in 2012, the SCAT 3rd edition (Child SCAT3) was developed for children aged between 5 and12 years. Research to date was reviewed and synthesised for the 5th International Consensus Conference on Concussion in Sport in Berlin, Germany, leading to the current revision of the test, the Child SCAT5. This article describes the development of the Child SCAT5.

The Concussion Recognition Tool 5th Edition (CRT5): Background and rationale.

The Concussion Recognition Tool 5 (CRT5) is the most recent revision of the Pocket Sport Concussion Assessment Tool 2 that was initially introduced by the Concussion in Sport Group in 2005. The CRT5 is designed to assist non-medically trained individuals to recognise the signs and symptoms of possible sport-related concussion and provides guidance for removing an athlete from play/sport and to seek medical attention. This paper presents the development of the CRT5 and highlights the differences between the CRT5 and prior versions of the instrument.

The Sport Concussion Assessment Tool 5th Edition (SCAT5): Background and rationale.

This paper presents the Sport Concussion Assessment Tool 5th Edition (SCAT5), which is the most recent revision of a sport concussion evaluation tool for use by healthcare professionals in the acute evaluation of suspected concussion. The revision of the SCAT3 (first published in 2013) culminated in the SCAT5. The revision was based on a systematic review and synthesis of current research, public input and expert panel review as part of the 5th International Consensus Conference on Concussion in Sport held in Berlin in 2016. The SCAT5 is intended for use in those who are 13 years of age or older. The Child SCAT5 is a tool for those aged 5-12 years, which is discussed elsewhere.

Is Migraine Headache Associated With Concussion in Athletes? A Case-Control Study.

OBJECTIVE: The purpose of this study was to investigate the association between migraine headache and concussion in athletes. DESIGN: Case-control observational study. SETTING: A university-associated combined sports neurology and orthopedic sports medicine clinic. PARTICIPANTS: A total of 221 male (n = 140) and female (n = 81) athletes aged 12 to 24 years, including 115 concussion cases (52%) and 106 orthopedic controls (48%), were included in this study. INTERVENTIONS: Participants completed a one-page questionnaire that recorded their age, sex, reason for visit (concussion vs any other injury), concussion history, and self/immediate family member migraine headache history. MAIN OUTCOME MEASURES: The odds of having a previous history of migraine headache were compared in the concussion group versus orthopedic controls. RESULTS: Controlling for between-group differences in age and sex, there was a significant positive association between concussion group status and history of migraine headache [adjusted odds ratio (OR), 1.90; 95% confidence interval (CI), 1.03-3.50. P = 0.039]. However, when including a previous concussion history in the statistical model, this relationship failed to reach significance [adjusted OR, 1.68; 95% CI, 0.89-3.16. P = 0.107]. CONCLUSIONS: These results suggest that there is an association between migraine headache and concussion in athletes, but the cause-effect nature of this relationship cannot be determined. Migraine headache should be considered a modifying factor when caring for concussed athletes.

Developing guidelines for return to play: consensus and evidence-based approaches.

BACKGROUND: Sports-related concussions are commonplace at all levels of play and across all age groups. The dynamic, evolving nature of this injury coupled with a lack of objective biomarkers creates a challenging management issue for the sports medicine team. Athletes who return to play following a concussion are known to be at higher risk for an additional brain injury, which necessitates a careful, informed return to play (RTP) process. AIM: The goal of this paper is to outline historical attempts at developing RTP guidelines and trace their evolution over time, culminating in a discussion of the process and outcomes of the most recent consensus statements/guidelines published by the international Concussion In Sport Group (CISG), the American Academy of Neurology (AAN), the National Athletic Trainers' Association, and the 2013 Team Physician Consensus Statement Update. METHOD: An evaluation of the pros and cons of these guidelines is presented along with suggestions for future directions. In addition, the Institute of Medicine recently conducted a comprehensive report outlining the current state of evidence regarding youth concussions, which provides specific recommendations for future research. CONCLUSIONS: The different methodologies utilized in the development of consensus statements have distinct advantages and disadvantages, and both approaches add value to the everyday management of sports concussions. Importantly, the overall approach for management of sports concussion is remarkably similar using either consensus-based or formal evidence-based methods, which adds confidence to the current guidelines and allows practitioners to focus on accepted standards of clinical care. Moving forward, careful study designs need to be utilized to avoid bias in selection of research subjects, collection of data, and interpretation of results. Although useful, clinicians must venture beyond consensus statements to examine reviews of the literature that are published in much greater frequency than consensus statements.

Effect of sport-related concussion on clinically measured simple reaction time.

BACKGROUND: Reaction time (RT) is a valuable component of the sport concussion assessment battery. RT is typically measured using computers running specialised software, which limits its applicability in some athletic settings and populations. To address this, we developed a simple clinical test of RT (RTclin) that involves grasping a falling measuring stick. PURPOSE: To determine the effect of concussion on RTclin and its sensitivity and specificity for concussion. MATERIALS AND METHODS: Concussed athletes (n=28) and non-concussed control team-mates (n=28) completed RTclin assessments at baseline and within 48 h of injury. Repeated measures analysis of variance compared mean baseline and follow-up RTclin values between groups. Sensitivity and specificity were calculated over a range of reliable change confidence levels. RESULTS: RTclin differed significantly between groups (p<0.001): there was significant prolongation from baseline to postinjury in the concussed group (p=0.003), with a trend towards improvement in the control group (p=0.058). Sensitivity and specificity were maximised when a critical change value of 0 ms was applied (ie, any increase in RTclin from baseline was interpreted as abnormal), which corresponded to a sensitivity of 75%, specificity of 68% and a 65% reliable change confidence level. CONCLUSIONS: RTclin appears sensitive to the effects of concussion and distinguished concussed and non-concussed athletes with similar sensitivity and specificity to other commonly used concussion assessment tools. Given its simplicity, low cost and minimal time requirement, RTclin should be considered a viable component of the sports medicine provider's multifaceted concussion assessment battery.

What is the lowest threshold to make a diagnosis of concussion?

OBJECTIVE: The purpose of this review is to examine the evidence for determining the lowest threshold for diagnosing a sport-related concussion. DATA SOURCES: MEDLINE, CINAHL, EMBASE, Mosby's Index, PsycEXTRA, PsycINFO and Scopus. Key words included sports concussion, concussion assessment, diagnosis, concussion symptoms, onfield assessment and sports-related traumatic brain injury. RESULTS: The majority of concussions in sport occur without loss of consciousness or frank neurological signs. Some of the hallmark signs of acute concussion include mental confusion, memory and balance disturbance. Over the course of the first 24 h, the most common symptoms include headache, nausea, dizziness and balance problems, blurred vision or other visual disturbance, confusion, memory loss and 'fatigue'. Symptoms such as tiredness, irritability, nervousness or anxiety, sleep disturbance and sensitivity to light or noise may be noticed in the days after injury. The pathophysiology of sports concussion remains poorly understood. There appears to be a period of vulnerability following concussion in which an overlapping injury might cause magnified pathophysiology. CONCLUSIONS: Sport-related concussions can be difficult to diagnose. Concussion produces an evolving constellation of somatic, cognitive and neurobehavioral symptoms that are typically most severe during the earliest acute postinjury period (ie, within the first 24-48 h) and diminish over a matter of several days to weeks in the majority of athletes. Athletes suspected of concussion should be removed from play and evaluated thoroughly.

What evidence exists for new strategies or technologies in the diagnosis of sports concussion and assessment of recovery?

OBJECTIVE: The purpose of this critical review is to summarise the evidence for the following technologies/strategies related to diagnosing or managing sports-related concussion: quantitative EEG, functional neuroimaging, head impact sensors, telemedicine and mobile devices. DATA SOURCES: MEDLINE, PubMed, Cochrane Controlled Trials Registers, SportDiscus, EMBASE, Web of Science and ProQuest databases. Primary search keywords were concussion, sports concussion and mild traumatic brain injury. The keywords used for secondary, topic specific searches were quantitative electroencephalography, qEEG, functionalMRI, magnetoencephalography, near-infrared spectroscopy, positron emission tomography, single photon emissionCT, accelerometer, impact sensor, telemetry, remote monitoring, robotic medicine, telemedicine, mobile device, mobile phone, smart phone and tablet computer. RESULTS: The primary search produced 8567 publications. The secondary searches produced nine publications that presented original data, included a comparison group in the study design and involved sports-related concussion. Four studies spoke to the potential of qEEG as a diagnostic or management tool, while five studies addressed the potential of fMRI to be used in the same capacity. CONCLUSIONS: Emerging technologies and novel approaches that aid in sports concussion diagnosis and management are being introduced at a rapid rate. While some technologies show promise, their clinical utility remains to be established.

What is the evidence for chronic concussion-related changes in retired athletes: behavioural, pathological and clinical outcomes?

OBJECTIVE: The purpose of this paper was to review the current state of evidence for chronic traumatic encephalopathy (CTE) in retired athletes and to consider the potential differential diagnoses that require consideration when retired athletes present with cognitive and psychiatric problems. DATA SOURCES: MEDLINE, CINAHL, EMBASE, Mosby's Index, PsycEXTRA, PsycINFO and Scopus. Key words included CTE, dementia pugilistica, punch drunk syndrome, traumatic encephalopathy, CTE, repetitive head injury, sports concussion, multiple concussions, chronic concussions, subconcussive blow and sports-related traumatic brain injury. RESULTS: At present, there are no published epidemiological, cross-sectional or prospective studies relating to modern CTE. Owing to the nature of the published studies, being case reports or pathological case series, it is not possible to determine the causality or risk factors with any certainty. As such, the speculation that repeated concussion or subconcussive impacts cause CTE remains unproven. The extent to which age-related changes, psychiatric or mental health illness, alcohol/drug use or coexisting dementing illnesses contribute to this process is largely unaccounted for in the published literature. CONCLUSIONS: At present, the interpretation of causation in the modern CTE case studies should proceed cautiously. The causal assumptions require further prospective or longitudinal studies on the topic.

American Medical Society for Sports Medicine position statement: concussion in sport.

PURPOSE OF THE STATEMENT: ▸ To provide an evidence-based, best practises summary to assist physicians with the evaluation and management of sports concussion. ▸ To establish the level of evidence, knowledge gaps and areas requiring additional research. IMPORTANCE OF AN AMSSM STATEMENT: ▸ Sports medicine physicians are frequently involved in the care of patients with sports concussion. ▸ Sports medicine physicians are specifically trained to provide care along the continuum of sports concussion from the acute injury to return-to-play (RTP) decisions. ▸ The care of athletes with sports concussion is ideally performed by healthcare professionals with specific training and experience in the assessment and management of concussion. Competence should be determined by training and experience, not dictated by specialty. ▸ While this statement is directed towards sports medicine physicians, it may also assist other physicians and healthcare professionals in the care of patients with sports concussion. DEFINITION: ▸ Concussion is defined as a traumatically induced transient disturbance of brain function and involves a complex pathophysiological process. Concussion is a subset of mild traumatic brain injury (MTBI) which is generally self-limited and at the less-severe end of the brain injury spectrum. PATHOPHYSIOLOGY: ▸ Animal and human studies support the concept of postconcussive vulnerability, showing that a second blow before the brain has recovered results in worsening metabolic changes within the cell. ▸ Experimental evidence suggests the concussed brain is less responsive to usual neural activation and when premature cognitive or physical activity occurs before complete recovery the brain may be vulnerable to prolonged dysfunction. INCIDENCE: ▸ It is estimated that as many as 3.8 million concussions occur in the USA per year during competitive sports and recreational activities; however, as many as 50% of the concussions may go unreported. ▸ Concussions occur in all sports with the highest incidence in football, hockey, rugby, soccer and basketball. RISK FACTORS FOR SPORT-RELATED CONCUSSION: ▸ A history of concussion is associated with a higher risk of sustaining another concussion. ▸ A greater number, severity and duration of symptoms after a concussion are predictors of a prolonged recovery. ▸ In sports with similar playing rules, the reported incidence of concussion is higher in female athletes than in male athletes. ▸ Certain sports, positions and individual playing styles have a greater risk of concussion. ▸ Youth athletes may have a more prolonged recovery and are more susceptible to a concussion accompanied by a catastrophic injury. ▸ Preinjury mood disorders, learning disorders, attention-deficit disorders (ADD/ADHD) and migraine headaches complicate diagnosis and management of a concussion. DIAGNOSIS OF CONCUSSION: ▸ Concussion remains a clinical diagnosis ideally made by a healthcare provider familiar with the athlete and knowledgeable in the recognition and evaluation of concussion. ▸ Graded symptom checklists provide an objective tool for assessing a variety of symptoms related to concussions, while also tracking the severity of those symptoms over serial evaluations. ▸ Standardised assessment tools provide a helpful structure for the evaluation of concussion, although limited validation of these assessment tools is available. SIDELINE EVALUATION AND MANAGEMENT: ▸ Any athlete suspected of having a concussion should be stopped from playing and assessed by a licenced healthcare provider trained in the evaluation and management of concussions. ▸ Recognition and initial assessment of a concussion should be guided by a symptoms checklist, cognitive evaluation (including orientation, past and immediate memory, new learning and concentration), balance tests and further neurological physical examination. ▸ While standardised sideline tests are a useful framework for examination, the sensitivity, specificity, validity and reliability of these tests among different age groups, cultural groups and settings is largely undefined. Their practical usefulness with or without an individual baseline test is also largely unknown. ▸ Balance disturbance is a specific indicator of a concussion, but not very sensitive. Balance testing on the sideline may be substantially different than baseline tests because of differences in shoe/cleat-type or surface, use of ankle tape or braces, or the presence of other lower extremity injury. ▸ Imaging is reserved for athletes where intracerebral bleeding is suspected. ▸ There is no same day RTP for an athlete diagnosed with a concussion. ▸ Athletes suspected or diagnosed with a concussion should be monitored for deteriorating physical or mental status. NEUROPSYCHOLOGICAL TESTING: ▸ Neuropsychological (NP) tests are an objective measure of brain-behaviour relationships and are more sensitive for subtle cognitive impairment than clinical exam. ▸ Most concussions can be managed appropriately without the use of NP testing. ▸ Computerised neuropsychological (CNP) testing should be interpreted by healthcare professionals trained and familiar with the type of test and the individual test limitations, including a knowledgeable assessment of the reliable change index, baseline variability and false-positive and false-negative rates. ▸ Paper and pencil NP tests can be more comprehensive, test different domains and assess for other conditions which may masquerade as or complicate assessment of concussion. ▸ NP testing should be used only as part of a comprehensive concussion management strategy and should not be used in isolation. ▸ The ideal timing, frequency and type of NP testing have not been determined. ▸ In some cases, properly administered and interpreted NP testing provides an added value to assess cognitive function and recovery in the management of sports concussions. ▸ It is unknown if use of NP testing in the management of sports concussion helps prevent recurrent concussion, catastrophic injury or long-term complications. ▸ Comprehensive NP evaluation is helpful in the post-concussion management of athletes with persistent symptoms or complicated courses. RETURN TO CLASS: ▸ Students will require cognitive rest and may require academic accommodations such as reduced workload and extended time for tests while recovering from a concussion. RETURN TO PLAY: ▸ Concussion symptoms should be resolved before returning to exercise. ▸ A RTP progression involves a gradual, step-wise increase in physical demands, sports-specific activities and the risk for contact. ▸ If symptoms occur with activity, the progression should be halted and restarted at the preceding symptom-free step. ▸ RTP after concussion should occur only with medical clearance from a licenced healthcare provider trained in the evaluation and management of concussions. SHORT-TERM RISKS OF PREMATURE RTP: ▸ The primary concern with early RTP is decreased reaction time leading to an increased risk of a repeat concussion or other injury and prolongation of symptoms. LONG-TERM EFFECTS: ▸ There is an increasing concern that head impact exposure and recurrent concussions contribute to long-term neurological sequelae. ▸ Some studies have suggested an association between prior concussions and chronic cognitive dysfunction. Large-scale epidemiological studies are needed to more clearly define risk factors and causation of any long-term neurological impairment. DISQUALIFICATION FROM SPORT: ▸ There are no evidence-based guidelines for disqualifying/retiring an athlete from a sport after a concussion. Each case should be carefully deliberated and an individualised approach to determining disqualification taken. EDUCATION: ▸ Greater efforts are needed to educate involved parties, including athletes, parents, coaches, officials, school administrators and healthcare providers to improve concussion recognition, management and prevention. ▸ Physicians should be prepared to provide counselling regarding potential long-term consequences of a concussion and recurrent concussions. PREVENTION: ▸ Primary prevention of some injuries may be possible with modification and enforcement of the rules and fair play. ▸ Helmets, both hard (football, lacrosse and hockey) and soft (soccer, rugby) are best suited to prevent impact injuries (fracture, bleeding, laceration, etc.) but have not been shown to reduce the incidence and severity of concussions. ▸ There is no current evidence that mouth guards can reduce the severity of or prevent concussions. ▸ Secondary prevention may be possible by appropriate RTP management. LEGISLATION: ▸ Legislative efforts provide a uniform standard for scholastic and non-scholastic sports organisations regarding concussion safety and management. FUTURE DIRECTIONS: ▸ Additional research is needed to validate current assessment tools, delineate the role of NP testing and improve identification of those at risk of prolonged post-concussive symptoms or other long-term complications. ▸ Evolving technologies for the diagnosis of concussion, such as newer neuroimaging techniques or biological markers, may provide new insights into the evaluation and management of sports concussion.

Unrecognised ringside concussive injury in amateur boxers.

OBJECTIVES: Concussion is common in contact sports such as boxing. Diagnosis of concussion depends on symptom report or recognition of clinical features, and true incidence may be underestimated. Persistent morbidity is a possible risk of repeated or unrecognised concussion. This study aimed to evaluate pre and postbout cognitive performance in motivated amateur boxers in order to detect objective evidence of unrecognised cognitive impairment suggestive of concussive injury. METHODS: The study employed a prospective and observational design. Participants were amateur boxers who won at least one bout in a single elimination competition. Optimal preparticipation performance using a computerised cognitive assessment tool (CCAT, Axon Sports) and no significant deterioration in cognitive performance within 24 h postbout were required to compete. All boxers were screened for clinical evidence of concussion by a ringside physician. RESULTS: Of approximately 200 competing boxers, 96 were eligible having won at least one of the total 160 bouts. Mean age was 21.3 (SD 1.9) years (range 18.5-29.7). Of these, 17 (10.6%) failed their first postbout CCAT, with 12 (71%) passing a repeat test. Of the five remaining boxers, there were two boxers (1.3% of bouts) not suspected of a concussion after their bouts, who showed evolving slowing in cognitive performance typical of a concussion. CONCLUSIONS: Cognitive impairment, as detected by subtle deterioration in reaction time measures, can occur in amateur boxers postbout that is not recognised at ringside. Although the vast majority of bouts were conducted safely, unrecognised injury may occur and be detectable using objective computerised cognitive assessment.

Treatment of attention-deficit hyperactivity disorder in athletes.

Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral development disorder affecting an estimated 6% to 9% of youth in the United States. The typical manifestations of ADHD, attention difficulties and hyperactivity, cause impairment in social and academic functioning, while common comorbid conditions can add significantly to the disease burden. Diagnosing ADHD requires a comprehensive clinical approach. Many medications have been shown to provide benefit for patients with ADHD, and a positive response to medication can be an important factor in clarifying the diagnosis. Medical therapy is of particular interest when treating athletes, as competitive bodies ban many treatment options. This review provides the sports medicine provider with a framework for the treatment of ADHD in the athlete.

Concussion symptom scales and sideline assessment tools: a critical literature update.

Sports-related concussion remains a diagnostic and management challenge for the sports medicine practitioner. Numerous symptom scales and sideline assessment tools are available for team physicians and athletic trainers to objectively assess this difficult injury. The purpose of this article is to update the reader on literature published within the past year relevant to concussion symptom scales and sideline assessment tools. A critical evaluation of pertinent articles is presented. We conclude that multiple symptom scales and assessment tools are available, with no single tool showing clear superiority. Many tools remain based more on expert opinion than rigorous scientific evaluation. A multifaceted approach to sports concussion is advised. The sports medicine practitioner must not rely on any one tool in managing concussion and must be aware of the strengths and limitations of whichever method is chosen to incorporate into a concussion evaluation and management plan.

At-risk populations in sports-related concussion.

Concussion is a physiological injury to the extremely complex and dynamic human brain. Individual variability adds to the challenge of concussion management, and sports medicine practitioners recently have begun to realize the need for an individualized approach. Adequately assessing an athlete with concussion requires consideration of many risk factors, including age, gender, and certain comorbid conditions. Understanding how these factors may affect concussion risk and outcome is becoming an essential aspect of management. This article reviews what is known or assumed about how some of these risk factors affect concussion. We conclude by providing several key concepts that we feel are important to keep in mind when managing an athlete with concussion.