Predicting and preventing postconcussive problems in paediatrics (5P) study: protocol for a prospective multicentre clinical prediction rule derivation study in children with concussion The reliability and validity of video analysis for the assessment of the clinical signs of concussion in Australian football. Evaluation of Neuropsychological Domain Scores and Postural Stability Following Cerebral Concussion in Sports Is neuropsychological testing useful in the management of sport-related concussion? Examining Sport Concussion Assessment Tool ratings for male and female youth hockey players with and without a history of concussion The assessment of orientation following concussion in athletes. Evaluation of the King–Devick test as a concussion screening tool in high school football players The “Value Added” of Neurocognitive Testing after Sports-Related Concussion Grade 1 or “Ding” Concussions in High School Athletes Prevalence of neurocognitive and balance deficits in collegiate aged football players without clinically diagnosed concussion. Cognition in the days following concussion: comparison of symptomatic versus asymptomatic athletes. Detailed concussion symptom analysis in a paediatric ED population Acute Effects and Recovery After Sport‐Related Concussion: A Neurocognitive and Quantitative Brain Electrical Activity Study Evaluating the cognitive consequences of mild traumatic brain injury and concussion by using electrophysiology. HISTORY OF MULTIPLE SELF‐REPORTED CONCUSSIONS IS NOT ASSOCIATED WITH REDUCED COGNITIVE ABILITIES Pediatric concussions in United States emergency departments in the years 2002 to 2006. Epidemiology of sports-related concussion in seven US high school and collegiate sports
Introduction Persistent postconcussive symptoms ( PCSs ) is the persistence of somatic , cognitive , physical , psychological and /or behavioural changes lasting more than 1 month following concussion . Persistent concussion impacts the quality of life through impaired cognition , memory and attention affecting school performance , mood and social engagement . No large epidemiological studies have determined the true prevalence of persistent concussion symptoms . Vali date d , easy-to-use prognosticators do not exist for clinicians to identify children at highest risk . The goal of Predicting and Preventing Postconcussive Problems in Pediatrics study is to derive a clinical prediction rule for the development of persistent postconcussion symptoms in children and adolescents presenting to emergency department following acute head injury . Methods and analysis This study is a prospect i ve , multicentre cohort study across nine academic Canadian paediatric emergency departments . We will recruit the largest prospect i ve epidemiological cohort of children with concussion . Eligible children will be followed using  Post-Concussion Symptom Inventory , a vali date d tool in children as young as 5 years . Patients will follow-up at 1 , 2 , 4 , 8 and 12 weeks postinjury . The main outcome will be the presence/absence of PCSs defined as three or more persistent concussion symptoms 1 month following the injury .  1792 patients provide adequate power to derive a clinical decision rule using multivariate analyses to find predictor variables sensitive for detecting cases of persistent postconcussion symptoms . Ethics and dissemination Results of this large prospect i ve study will enable clinicians to identify children at highest risk , optimise treatment and provide families with realistic and appropriate anticipatory guidance . Ethics has been obtained through the Children 's Hospital of Eastern Ontario Research Ethics Board . Results will be disseminated at international conferences and in four manuscripts to peer- review ed journals . Trial registration This study is registered at Clinical trials.gov through the US National Institute of Health/National Library of Medicine ( NCT01873287 ; http:// clinical trials.gov/ct2/show/NCT01873287 ) OBJECTIVES The objective of this study was to determine the reliability and validity of identifying clinical signs of concussion using  video analysis in Australian football . DESIGN Prospect i ve cohort study . METHODS All impacts and collisions potentially result ing in a concussion were identified during 2012 and 2013 Australian Football League seasons . Consensus definitions were developed for clinical signs associated with concussion . For intra- and inter-rater reliability analysis , two experienced clinicians independently assessed 102 r and omly selected videos  on two occasions . Sensitivity , specificity , positive and negative predictive values were calculated based on the diagnosis provided by team medical staff . RESULTS 212 incidents result ing in possible concussion were identified in 414 Australian Football League games . The intra-rater reliability of the  video-based identification of signs associated with concussion was good to excellent . Inter-rater reliability was good to excellent for impact seizure , slow to get up , motor incoordination , ragdoll appearance ( 2 of 4 analyses ) , clutching at head and facial injury . Inter-rater reliability for loss of responsiveness and blank and vacant look was only fair and did not reach statistical significance . The feature with the highest sensitivity was slow to get up ( 87 % ) , but this sign had a low specificity ( 19 % ) . Other video signs had a high specificity but low sensitivity . Blank and vacant look ( 100 % ) and motor incoordination ( 81 % ) had the highest positive predictive value . CONCLUSIONS Video analysis may be a useful adjunct to the side-line assessment of a possible concussion . Video analysis however should not replace the need for a thorough multimodal clinical assessment Context With increasing knowledge and research about concussion , there have been few objective studies that have used neuropsychological domain scores and postural stability to assess concussion . Objective To evaluate the recovery curve of athletes who incur sport-related concussion from repeated serial testing of neuropsychological and posturography testing . Design A prospect i ve epidemiological model was used for the course of the study . Setting Division I intercollegiate athletics . Participants Athletes participating in football , soccer , basketball , softball , and cheerleading . Main Outcome Measures  Neuropsychological scores and posturography measures  were obtained preseason and serially at day 1 , day 2 , day 3 , and day 10 postconcussion .  Control participants  were tested at the same intervals .  Neuropsychological scores were converted to st and ards score and then into domains of attention , learning , speed of information processing , concentration , memory , and verbal fluency . Analysis of covariance with the baseline test as the covariate was used to analyze the data with univariate post hoc tests performed . Results Significant group differences were found for self reported symptoms ( P = 0.001 ) , speed of information processing ( P = 0.005 ) , mean stability ( P = 0.002 ) , and vestibular function ( P = 0.003 ) between injured and control participants . A group , by day , planned comparison found that speed of information processing and composite balance measures demonstrated significant differences through day 10 postinjury , while symptoms and the vestibular ratio remained significant only through day 3 . Conclusions The concussion recovery curve demonstrated short-term neuropsychological and posturography deficits following injury . A comprehensive approach to concussion management should be used to assess the injury and make return-to-play decisions OBJECTIVE Neuropsychological ( NP ) testing has been used for several years as a way of detecting the effects of sport-related concussion in order to aid in return-to-play determinations . In addition to st and ard pencil- and -paper tests , computerized NP tests are being commercially marketed for this purpose to professional , collegiate , high school , and elementary school programs . However , a number of important questions regarding the clinical validity and utility of these tests remain unanswered , and these questions present serious challenges to the applicability of NP testing for the management of sport-related concussion . Our purpose is to outline the criteria that should be met in order to establish the utility of NP instruments as a tool in the management of sport-related concussion and to review the degree to which existing tests have met these criteria . DATA SOURCES A comprehensive literature review of MEDLINE and PsychLit from 1990 to 2004 , including all prospect i ve , controlled studies of NP testing in sport-related concussion . DATA SYNTHESIS The effects of concussion on NP test performance are so subtle even during the acute phase of injury ( 1 - 3 days postinjury ) that they often fail to reach statistical significance in group studies . Thus , this method may lack utility in individual decision making because of a lack of sensitivity . In addition , most of these tests fail to meet other psychometric criteria ( eg , adequate reliability ) necessary for this purpose . Finally , it is unclear that NP testing can detect impairment in players once concussion-related symptoms ( eg , headache ) have resolved . Because no current guideline for the management of sport-related concussion allows a symptomatic player to return to sport , the incremental utility of NP testing remains question able . CONCLUSIONS / RECOMMENDATIONS Despite the theoretic rationale for the use of NP testing in the management of sport-related concussion , no NP tests have met the necessary criteria to support a clinical application at this time . Additional research is necessary to establish the utility of these tests before they can be considered part of a routine st and ard of care , and concussion recovery should be monitored via the st and ard clinical examination and subjective symptom checklists until NP testing or other methods are proven effective for this purpose Background Concussion is one of the most commonly occurring injuries in sport today . The Sport Concussion Assessment Tool ( SCAT ) is a commonly used paper neurocognitive tool . To date , little is known about SCAT baseline normative values in youth athletes . Objective The purpose of this study was to determine normative values on the SCAT for male and female youth hockey players . Methods This is a secondary data analysis of pooled data from three prospect i ve cohort studies examining the risk of injury in paediatric ice hockey players aged 9–17 years . A preseason baseline demographic and injury history question naire was completed by each player . Results A total of 4193 players completed SCATs at baseline and were included in the analysis . 781 players ( 18.6 % ) reported a previous history of concussion . Fatigue and low energy followed by headache were the most commonly reported symptoms in all players . The majority of youth players could recite all five words immediately but only three words when delayed . A smaller proportion of the males were able to report the months of the year in reverse order compared with females of a similar age . The median number of digits recited in reverse order was 4 . Conclusions Youth ratings varied between age groups , gender and from previously reported ratings of varsity athletes , possibly reflecting developmental and gender differences . An underst and ing of these differences in youth athletes is important to ensure appropriate performance expectations on the SCAT and when making clinical decisions following a concussion The purpose of this study was to investigate the sensitivity of  orientation and recent memory questions  in the diagnosis of concussion . In a prospect i ve study over 7 consecutive years ( 1985 - 1991 ) , all players at a professional Australian Rules Football club who sustained a concussive injury ( n = 28 ) were administered a set of questions evaluating orientation and recent memory .  Concussion was diagnosed independently on the basis of loss or disturbance of consciousness and clinical symptoms . A control group of age-matched nonconcussed players was administered the same set of questions . The results showed that items evaluating recently acquired information were more sensitive in the assessment of concussion than st and ard orientation items . The relative sensitivity of orientation questions must be considered when they are used in the clinical diagnosis of concussion in sport OBJECTIVE Concussion is the most common type of traumatic brain injury , and results from impact or impulsive forces to the head , neck or face . Due to the variability and subtlety of symptoms , concussions may go unrecognized or be ignored , especially with the pressure placed on athletes to return to competition . The King-Devick ( KD ) test , an oculomotor test originally design ed for reading evaluation , was recently vali date d as a concussion screening tool in collegiate athletes . A prospect i ve study was performed using high school football players in an attempt to study the KD as a concussion screening tool in this younger population . METHODS 343 athletes from four local high school football teams were recruited to participate . These athletes were given baseline KD tests prior to competition . Individual demographic information was collected on the subjects . St and ard team protocol was employed to determine if a concussion had occurred during competition . Immediately after diagnosis , the KD test was re-administered to the concussed athlete for comparison to baseline . Post-season testing was also performed in non-concussed individuals . RESULTS Of the 343 athletes , nine were diagnosed with concussions . In all concussed players , cumulative read times for the KD test were significantly increased ( p<0.001 ) . Post-season testing of non-concussed athletes revealed minimal change in read times relative to baseline . Univariate analysis revealed that history of concussion was the only demographic factor predictive of concussion in this cohort . CONCLUSION The KD test is an accurate and easily administered sideline screening tool for concussion in adolescent football players Background Neurocognitive testing has been endorsed as a “ cornerstone ’ of concussion management by recent Vienna and Prague meetings of the Concussion in Sport Group . Neurocognitive testing is important given the potential unreliability of athlete self-report after injury . Relying only on athletes'ormalities after injury . Study Design Case control study ; Level of evidence , 3 . Methods High school and college athletes with a diagnosed concussion were tested 2 days after injury . Postinjury neurocognitive performance ( Immediate Postconcussion Assessment and Cognitive Testing ) and symptom ( postconcussion symptom ) scores were compared with preinjury ( baseline ) scores and with those of an agex and education-matched noninjured athlete control group . “ Abnormal ” test performance was determined statistically with Reliable Change Index scores . Results Sixty-four percent of concussed athletes reported a significant increase in symptoms , as judged by postconcussion symptom scores , compared with preinjury baseline at 2 days after injury . Eighty-three percent of the concussed sample demonstrated significantly poorer neurocognitive test results relative to their own baseline performance . The addition of neurocognitive testing result ed in a net increase in sensitivity of 19 % . Ninety-three percent of the sample had either abnormal neurocognitive test results or a significant increase in symptoms , relative to their own baseline ; 30 % of a control group demonstrated either abnormalities in neurocognitive testing or elevated symptoms , as judged by postconcussion symptom scores . For the concussed group , use of symptom and neurocognitive test results result ed in an increased yield of 29 % overreliance on symptoms alone . In contrast , 0 % of the control group had both symptoms and abnormal neurocognitive testing . Conclusion Reliance on patients ’ self-reported symptoms after concussion is likely to result in underdiagnosis of concussion and may result in premature return to play . Neurocognitive testing increases diagnostic accuracy when used in conjunction with self-reported symptoms Background Recent concussion management guidelines have suggested that athletes with mild ( grade 1 ) concussions may be returned to play if asymptomatic for 15 minutes . The purpose of this study was to assess the utility of a current concussion management guideline in classifying and managing mild concussion . Hypothesis High school athletes diagnosed with a grade 1 concussion will demonstrate measurable decline in neuropsychological functioning that persists during the 1st week of recovery . Study Design Prospect i ve study design ed to evaluate neuropsychological functioning both prior to and following concussion . Methods Forty-three high school athletes completed  neuropsychological test performance  and  symptom ratings  prior to the season and at two times during the 1st week following  mild concussion . Results Thirty-six hours after injury , mildly concussed high school athletes demonstrated a decline in memory ( P < 0.003 ) and a dramatic increase in self-reported symptoms ( P < 0.00001 ) compared to baseline performance . Conclusions Athletes with grade 1 concussion demonstrated memory deficits and symptoms that persisted beyond the context in which they were injured . These data suggest that current grade 1 return-to-play recommendations that allow for immediate return to play may be too liberal . Clinical Relevance A reconsideration of current concussion grading systems appears to be warranted STUDY DESIGN Prospect i ve cohort . OBJECTIVES To identify the prevalence of neurocognitive and balance deficits in collegiate football players 48 hours following competition . BACKGROUND Neurocognitive testing , balance assessment s , and subjective report of symptoms are a commonly used test battery in examining athletes when concussion is suspected . Previous literature suggests many concussions go unreported . Little research exists examining the prevalence of neurocognitive or balance deficits in athletes who do not report concussion-like symptoms to a health care provider . METHODS Forty-five Division IA collegiate football players participated in this study . Preseason baseline scores using the  Balance Error Scoring System , the Immediate Post-Concussion Assessment and Cognitive Testing , and the Postconcussion Symptom Scale  were compared to posttest results obtained 48 hours following a game . Prevalence of symptoms was analyzed and reported . RESULTS Thirty-two ( 71 % ) of the 45 athletes tested demonstrated at least 1 deficit in either the Postconcussion Symptom Scale , Balance Error Scoring System , or at least 1 composite score of the Immediate Post-Concussion Assessment and Cognitive Testing . Nineteen of the 32 subjects demonstrated a change in 2 or more categories of neurocognitive and balance function . CONCLUSION In a cohort of football players tested 48 hours following their last game of the season , who did not seek medical attention related to a concussion , a significant number demonstrated limitations in neurocognitive and balance performance , suggesting that further research may need to be performed to improve recognition of an athlete 's deficits and to improve the ability to assess concussion . LEVEL OF EVIDENCE Differential diagnosis/symptom prevalence , level 3b BACKGROUND Concussion is a common neurological injury occurring during contact sport . Current guidelines recommend that no athlete should return to play while symptomatic or displaying cognitive dysfunction . This study compared post-concussion cognitive function in recently concussed athletes who were symptomatic/asymptomatic at the time of assessment with that of non-injured ( control ) athletes . METHODS Prospect i ve study of 615 male Australian Rules footballers . Before the season , all participants ( while healthy ) completed a battery of baseline computerised ( CogSport ) and paper and pencil cognitive tasks .  Sixty one injured athletes ( symptomatic = 25 and asymptomatic = 36 ) were reassessed within 11 days of being concussed ; 84 controls were also reassessed . The serial cognitive function of the three groups was compared using analysis of variance . RESULTS The performance of the symptomatic group declined at the post-concussion assessment on computerised tests of simple , choice , and complex reaction times compared with the asymptomatic and control groups . The magnitude of changes was large according to conventional statistical criteria . On paper and pencil tests , the symptomatic group displayed no change at re assessment , whereas large improvements were seen in the other two groups . CONCLUSION Injured athletes experiencing symptoms of concussion displayed impaired motor function and attention , although their learning and memory were preserved . These athletes displayed no change in performance on paper and pencil tests in contrast with the improvement observed in asymptomatic and non-injured athletes . Athletes experiencing symptoms of concussion should be withheld from training and competition until both symptoms and cognitive dysfunction have resolved Primary objective : To examine the frequency of acute mild traumatic brain injury ( mTBI ) symptoms in children using a concussion symptom inventory  and to identify which symptoms are most useful in identifying mTBI . It was hypothesized that symptoms associated with mTBI are more common in children with head injury than orthopaedic injury and certain symptoms are more useful than others in identifying mTBI . Research design : Prospect i ve case-control study conducted in a paediatric trauma centre emergency department . Methods and procedures : Children of 6–18 years old with head injury or a minor extremity injury were enrolled .  Symptoms were assessed using a grade d symptom checklist .  Symptom frequency was compared using a chi-square test . The association between individual symptoms with AMS was evaluated with logistic regression analysis . Main outcomes and results : Children with head injury displayed more frequent symptoms than controls . Head-injured cases with altered mental status ( AMS ) demonstrated the most frequent and severe symptoms ( median symptom scores : control = 1 , cases without AMS = 5 , cases with AMS = 10 ; p < 0.001 ) . Headache , nausea , dizziness , blurred/double vision and not feeling ‘ sharp ’ were associated with AMS . Conclusions : Symptoms associated with mTBI are more frequent in children with head injury . AMS magnifies this effect . A symptom inventory is integral to the evaluation of mTBI in children ; a smaller set of dichotomized symptoms may be as useful as and more easily administered than lengthier symptom scales Objective To investigate the clinical utility and sensitivity of a portable , automatic , frontal quantitative electroencephalographic ( QEEG ) acquisition device currently in development in detecting abnormal brain electrical activity after sport-related concussion . Design This was a prospect i ve , non-r and omized study of 396 high school and college football players , including cohorts of 28 athletes with concussion and 28 matched controls . All subjects underwent preseason baseline testing on measures of postconcussive symptoms , postural stability , and cognitive functioning , as well as QEEG . Clinical testing and QEEG were repeated on day of injury and days 8 and 45 postinjury for the concussion and control groups . Main Outcomes and Results The injured group reported more significant postconcussive symptoms during the first 3 days postinjury , which resolved by days 5 and 8 . Injured subjects also performed poorer than controls on neurocognitive testing on the day of injury , but no differences were evident on day 8 or day 45 . QEEG studies revealed significant abnormalities in electrical brain activity in the injured group on day of injury and day 8 postinjury , but not on day 45 . Conclusions Results from the current study on clinical recovery after sport-related concussion are consistent with early reports indicating a typical course of full recovery in symptoms and cognitive dysfunction within the first week of injury . QEEG results , however , suggest that the duration of physiological recovery after concussion may extend longer than observed clinical recovery . Further study is required to replicate and extend these findings in a larger clinical sample , and further demonstrate the utility of QEEG as a marker of recovery after sport-related concussion OBJECT Mild traumatic brain injury ( MTBI ) , often referred to as concussion when it occurs in sports , produces persistent cognitive problems in at least 15 % of patients . Unfortunately , conventional neuropsychological tests usually yield results within normal limits in this population . The main objective of this event-related potential ( ERP ) study was to underst and brain functioning during the performance of a working memory ( WM ) task in patients who have sustained an MTBI , mostly due to motor vehicle accident or sports concussion . This study also aim ed for a better underst and ing of the association between brain functioning as measured with ERP , behavioral performance on the WM task , postconcussion symptoms , type of injury ( that is , sports concussion vs other types ) , and time since the injury . METHODS Forty-four patients with MTBI ( 7.6 ± 8.4 months postinjury ) were tested on a visual WM task with simultaneous recording of ERP , and were compared with 40 control volunteers who were their equivalent for age and sex . Amplitude and latency of frontal ( N200 and N350 ) and parietal ( P200 and P300 ) ERP waves were measured and were compared between groups . Correlation analyses were also performed between ERP characteristics , clinical variables , and behavioral performance . RESULTS A significant group difference was found for behavioral performance on the WM task , in which the MTBI group had a lower percentage of correct answers than the control group ( p < 0.05 ) . The patients with MTBI also had smaller amplitudes of both frontal N350 and parietal P300 ERP components when compared with control volunteers ( p < 0.05 ) . No changes were found for latency of ERP components . Smaller ERP amplitudes were associated with slower reaction times and worse accuracy on the WM task among patients with MTBI ( p < 0.05 ) . Types of injury ( that is , sports concussion vs other mechanisms ) were not associated with different ERP characteristics . CONCLUSIONS Abnormal ERP results are observed in patients after MTBI or sports concussion , even for those in the nonacute stage after their injury . Current st and ard clinical evaluations most often fail to detect cerebral dysfunction after MTBI , even when patients or athletes report symptoms . Clinicians should be aware that patients with MTBI , including sports concussion , probably have underlying mild but persistent cerebral dysfunctions that require further investigation OBJECTIVE The long-term impact of sports-related concussion is uncertain . Several studies using traditional neuropsychological measures have found a relationship between a previous history of concussion and reduced cognitive abilities . In contrast , studies using computerized neuropsychological measures have typically found no relationship between concussion history and cognition . In the present study , we examined the association between a self-reported concussion history and cognition using traditional and computer-based neuropsychological tests . METHODS A computerized neuropsychological battery was administered to a sample of 858 collegiate male athletes . Of this sample , 298 athletes reported a history of concussion . A traditional neuropsychological battery was administered to a separate sample of 479 male collegiate athletes , 187 of whom reported a history of concussion . Finally , both a computerized and a traditional neuropsychological battery were administered to a third distinct sample of 175 male collegiate athletes , 57 of whom reported a history of concussion . Concussion history was assessed via self-report . None of the athletes had been concussed in the 6 months before testing . RESULTS No significant association was found between self-reported concussion history and performance on either  computerized or traditional neuropsychological tests .  CONCLUSION Findings suggest that athletes who report a distant history of concussion have minimal enduring neurocognitive deficits . Given conflicting findings in the literature , prospect i ve studies that attempt to identify moderating factors are necessary to help determine who is at risk for long-term cognitive difficulties after concussion OBJECTIVES To estimate the incidence and demographics of concussions in children coming to emergency departments ( EDs ) in the United States and describe the rates of neuroimaging and follow-up instructions in these patients . STUDY DESIGN This is a cross-sectional study of children 0 to 19 years old diagnosed with concussion from the National Hospital Ambulatory Medical Care Survey . National Hospital Ambulatory Medical Care Survey collects data on approximately 25,000 visits annually to 600 r and omly selected hospital emergency and outpatient departments . We examined visits to United States emergency departments between 2002 and 2006 . Simple descriptive statistics were used . RESULTS Of the 50,835 pediatric visits in the 5-year sample , 230 observations , representing 144,000 visits annually , were for concussions . Sixty-nine percent of concussion visits were by males . Thirty percent were sports-related . Sixty-nine percent of patients diagnosed with a concussion had head imaging . Twenty-eight percent of patients were discharged without specific instructions to follow-up with an outpatient provider for further treatment . CONCLUSIONS Approximately 144,000 pediatric patients present to emergency departments each year with a concussion . Most of these patients undergo  computed tomography of the head , and nearly one-third are discharged without specific instructions to follow-up with an outpatient provider for further treatment Background The epidemiology of sports-related concussion is not well-described in the literature . This paper presents a descriptive epidemiology of concussion in seven high school and collegiate sports . Methods We used the data from Concussion Prevention Initiative ( CPI ) , which enrolled 8905 athletes at 210 high schools and 26 colleges in a prospect i ve cohort study of 7 sports ( football , men ’s and women ’s soccer , men ’s and women ’s lacrosse , and men ’s and women ’s ice hockey ) between 1999 and 2001 . Injury risks and injury rates were used to characterize the incidence of concussion , and changes in symptoms over time were described . Results A total of 375 concussions were observed . The incidence of concussion was highest in football , followed by women ’s lacrosse , men ’s lacrosse , men ’s soccer , and women ’s soccer ( only 10 ice hockey teams were included , too few to quantify incidence ) . The rate of incident concussion was strongly associated with history of concussion in the previous 24 months ( rate ratio = 5.5 ; 95 % CI : 3.9 , 7.8 , for 2 or more concussions relative to no previous concussion ) . The most common symptoms at time of injury were headache ( 87 % ) , balance problems/dizziness ( 77 % ) , and feeling “ in a fog ” ( 62 % ) . Loss of consciousness and amnesia were present in relatively few cases ( 9 and 30 % ) . The most common mechanism of injury was collision with another player . Conclusions Sports-related concussions present with a diverse range of symptoms and are associated with previous concussion history
: The results of this systematic review identify the consistent and prevalent indicators of concussion and their associations , derived from the strongest evidence in the published literature .
BACKGROUND : Currently , there is no evidence -based definition for concussion that is being uniformly applied in clinical and research setting s. OBJECTIVE : To conduct a systematic review of the highest- quality literature about concussion and to assemble evidence about the prevalence and associations of key indicators of concussion .
The goal was to establish an evidence -based foundation from which to derive , in future work , a definition , diagnostic criteria , and prognostic indicators for concussion .