Effect of concussion on clinically measured reaction time in 9 NCAA division I collegiate athletes: a preliminary study. Effect of acute exercise on clinically measured reaction time in collegiate athletes. Acute Effects and Recovery After Sport‐Related Concussion: A Neurocognitive and Quantitative Brain Electrical Activity Study Immediate Neurocognitive Effects of Concussion Evaluation of Neuropsychological Domain Scores and Postural Stability Following Cerebral Concussion in Sports Tracking Neurocognitive Performance following Concussion in High School Athletes Acute effects and recovery time following concussion in collegiate football players: the NCAA Concussion Study. Recovery of postural control after cerebral concussion: new insights using approximate entropy. Predictors of postconcussive symptoms 3 months after mild traumatic brain injury. Subject-Specific Increases in Serum S-100B Distinguish Sports-Related Concussion from Sports-Related Exertion Identifying neurocognitive deficits in adolescents following concussion. Depression and neurocognitive performance after concussion among male and female high school and collegiate athletes. Reliability of a Graded Exercise Test for Assessing Recovery From Concussion Long-term outcomes after uncomplicated mild traumatic brain injury: a comparison with trauma controls. Prediction of cognitive sequelae based on abnormal computed tomography findings in children following mild traumatic brain injury. Identifying high risk loading conditions for in-season injury in elite Australian football players. Recovery of cerebral blood flow following sports-related concussion.
OBJECTIVES To evaluate the effect of concussion on clinical ly measured reaction time ( RT(clin ) ) and in comparison to a computerized reaction time measure ( RT(comp ) ) . DESIGN Prospect i ve , repeated measures observational study . SETTING Athletic training clinic at a National Collegiate Athletic Association ( NCAA ) Division I university . PARTICIPANTS Data are reported for 9 collegiate athletes with acute concussion who were part of a larger cohort of 209 athletes recruited from the university 's football , women 's soccer , and wrestling teams before the start of their respective athletic seasons . METHODS  Baseline RT(clin ) and RT(comp )  were measured during preparticipation physical examinations . RT(clin ) measured the time required to catch a suspended vertical shaft by h and closure after its release by the examiner . RT(comp ) was derived from the simple RT component of the CogState-Sport computerized neurocognitive test battery . Athletes who subsequently sustained a physician-diagnosed concussion underwent repeated RT(clin ) and RT(comp ) testing within 72 hours of injury . A Wilcoxon signed rank test was used to compare baseline and after-injury RTs . MAIN OUTCOME MEASUREMENTS After-injury changes in RT(clin ) and RT(comp ) were calculated with respect to each athlete 's own preseason baseline value . RESULTS After-injury RT(clin ) was prolonged in 8 of the 9 athletes with concussions , whereas RT(comp ) was prolonged in 5 of the 9 athletes with concussions . The mean ( st and ard deviation ) RT(clin ) increased from 193 ± 21 ms to 219 ± 31 ms ( P = .050 ) , and mean RT(comp ) increased from 247 ± 75 to 462 ± 120 ms ( P = .214 ) . CONCLUSIONS We concluded that RT(clin ) appears to be sensitive to the known prolongation of RT after concussion and compares favorably with an accepted computerized RT measure . This study supports the potential utility of RT(clin ) as part of a multifaceted concussion assessment battery PURPOSE We have developed a reliable and valid clinical test of reaction time ( RTclin ) that is sensitive to the acute effects of concussion . If RTclin is to be used as a sideline concussion assessment tool then the acute effects of exercise on RTclin may need to be controlled for . The purpose of this study was therefore to determine the effect of exercise on RTclin . METHODS A gender-balanced group of 42 collegiate athletes were assigned to an  exercise ( n = 28 ) and a  control ( n = 14 ) group using 2:1 block r and omization . The exercise group completed a grade d four-stage exercise protocol on a stationary bicycle ( 100 W × 5 min ; 150 W × 5 min ; 200 W × 5 min ; sprint × 2 min ) , whereas the control group was tested at identical periods without exercising .  Mean RTclin was calculated for eight trials as the fall time of a vertically suspended rigid shaft after its release by the examiner before being caught by the athlete . RTclin was measured at baseline and after each of the four stages . RESULTS As both HR and RPE significantly increased for the four stages in the exercise group ( P < 0.001 ) , mean RTclin showed a significant overall decline during repeated test administration ( P < 0.008 ) . However , there were no significant group ( exercise vs control , P = 0.822 ) or group-by-stage interaction ( P = 0.169 ) effects on RTclin as assessed by repeated- measures analysis of variance . CONCLUSIONS Exercise did not appear to affect RTclin performance in this study . This suggests that RTclin measured during a sideline concussion assessment does not need to be adjusted to account for the acute effects of exercise 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 OBJECTIVE To prospect ively measure the immediate neurocognitive effects and early course of recovery from concussion and to examine the effects of loss of consciousness ( LOC ) and posttraumatic amnesia ( PTA ) on the severity of neurocognitive impairment immediately after concussion . METHODS A sports-related concussion research model was used to allow prospect i ve immediate evaluation of concussion . A total of 2385 high school and college football players were studied . Ninety-one players ( 3.8 % ) sustained concussions during the study . A brief neurocognitive and neurological screening measure , the St and ardized Assessment of Concussion  , was used to assess cognitive functioning before the football season , immediately after injury , and 15 minutes , 48 hours , and 90 days after injury . RESULTS St and ardized Assessment of Concussion scores immediately after concussion were significantly lower than the preseason baseline score and the noninjured population baseline mean , even for injured subjects without LOC or PTA . Subjects with LOC were most severely impaired immediately after injury , whereas those without LOC or PTA were least impaired . Significant impairment was also detected 15 minutes after injury , but all three groups returned to baseline levels of cognitive functioning within 48 hours . CONCLUSION These findings are the first to demonstrate not only that a gradient of increasing concussion severity is represented by PTA and LOC but also that measurable neurocognitive abnormalities are evident immediately after injury without PTA or LOC 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 Abstract Objective : To extend previous research design s and examine cognitive performance up to 30 days postconcussion . Method : A prospect i ve cohort design was used to examine 2000 athletes from 8 mid-Michigan area high schools to compare baseline neurocognitive performance with postconcussion neurocognitive performance . All concussed athletes were readministered the Immediate Post Assessment and Cognitive Test ( ImPACT ) at 2 , 7 , 14 , 21 , and 30 days postconcussion . Results : A total of 72 high school athletes ( aged 15.8 ± 1.34 years ) sustained a concussion . A significant with in-subjects effect for reaction time ( F = 10.01 ; P = 0.000 ) , verbal memory ( F = 3.05 ; P = 0.012 ) , motor processing speed ( F = 18.51 ; P = 0.000 ) , and total symptoms following an injury ( F = 16.45 ; P = 0.000 ) was found . Concussed athletes demonstrated a significant decrease in reaction time up to 14 days postconcussion ( P = 0.001 ) compared with baseline reaction time . Reaction time returned to baseline levels at 21 days postinjury ( P = 0.25 ) . At 7 days postinjury , impairments in verbal memory ( P = 0.003 ) and motor processing speed ( P = 0.000 ) were documented and returned to baseline levels by 14 days postinjury . Concussed athletes self-reported significantly more symptoms at 2 days postconcussion ( P = 0.000 ) and exhibited a resolution of symptoms by 7 days postinjury ( P = 0.06 ) . Conclusion : High school athletes could take up to 21 days to return to baseline levels for reaction time . These data support current recommendations for the conservative management of concussion in the high school athlete CONTEXT Lack of empirical data on recovery time following sport-related concussion hampers clinical decision making about return to play after injury . OBJECTIVE To prospect ively measure immediate effects and natural recovery course relating to symptoms , cognitive functioning , and postural stability following sport-related concussion . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve cohort study of 1631 football players from 15 US colleges . All players underwent preseason baseline testing on concussion assessment measures in 1999 , 2000 , and 2001 . Ninety-four players with concussion ( based on American Academy of Neurology criteria ) and 56 noninjured controls underwent assessment of symptoms  , cognitive functioning  , and postural stability immediately , 3 hours , and 1 , 2 , 3 , 5 , 7 , and 90 days after injury . MAIN OUTCOME MEASURES Scores on the Grade d Symptom Checklist ( GSC ) , St and ardized Assessment of Concussion ( SAC ) , Balance Error Scoring System ( BESS ) , and a neuropsychological test battery . RESULTS No player with concussion was excluded from participation ; 79 players with concussion ( 84 % ) completed the protocol through day 90 . Players with concussion exhibited more severe symptoms ( mean GSC score 20.93 [ 95 % confidence interval [ CI ] , 15.65 - 26.21 ] points higher than that of controls ) , cognitive impairment ( mean SAC score 2.94 [ 95 % CI , 1.50 - 4.38 ] points lower than that of controls ) , and balance problems ( mean BESS score 5.81 [ 95 % CI , -0.67 to 12.30 ] points higher than that of controls ) immediately after concussion . On average , symptoms gradually resolved by day 7 ( GSC mean difference , 0.33 ; 95 % CI , -1.41 to 2.06 ) , cognitive functioning improved to baseline levels within 5 to 7 days ( day 7 SAC mean difference , -0.03 ; 95 % CI , -1.33 to 1.26 ) , and balance deficits dissipated within 3 to 5 days after injury ( day 5 BESS mean difference , -0.31 ; 95 % CI , -3.02 to 2.40 ) . Mild impairments in cognitive processing and verbal memory evident on neuropsychological testing 2 days after concussion resolved by day 7 . There were no significant differences in symptoms or functional impairments in the concussion and control groups 90 days after concussion . CONCLUSIONS Collegiate football players may require several days for recovery of symptoms , cognitive dysfunction , and postural instability after concussion . Further research is required to determine factors that predict variability in recovery time after concussion . St and ardized measurement of postconcussive symptoms , cognitive functioning , and postural stability may enhance clinical management of athletes recovering from concussion CONTEXT The return-to-play decision after sport-related cerebral concussion depends in part on knowing when an athlete has fully recovered postural control after injury . OBJECTIVE To describe the postconcussion recovery of postural control using approximate entropy ( ApEn ) , a regularity statistic from nonlinear dynamics . DESIGN Retrospective case series analysis . SETTING Sports medicine research laboratory . PATIENTS OR OTHER PARTICIPANTS Collegiate athletes from whom center-of-pressure and symptom data were collected at preseason , less than 48 hours after injury , and 48 to 96 hours after injury . MAIN OUTCOME MEASURE(S ) Approximate entropy values reflecting the amount of r and omness contained in center-of-pressure oscillations were calculated for anterior-posterior ( AP ) and medial-lateral ( ML ) time series . Equilibrium scores reflecting the amplitude of center-of-pressure AP oscillations were used to indicate postural stability . The number and severity of symptoms were described . RESULTS Compared with the healthy preseason state , ApEn values for the AP and ML time series generally declined immediately after injury in both steady and unsteady injured athletes . At 48 to 96 hours after injury , ApEn values for the ML time series remained significantly depressed ( mean difference compared with preseason = -0.268 , st and ard error = 0.072 ) , even among athletes whose initial postural instability had resolved . We found few significant relationships between changes in ApEn values and changes in symptoms before and after injury . CONCLUSIONS The effects of cerebral concussion on postural control appear to persist for longer than 3 to 4 days , even among athletes with no signs of unsteadiness . Our results may reflect changes in neurophysiologic or mechanical constraints on postural control . Approximate entropy provides a theoretically distinct , valuable measurement alternative that may prove useful for reducing uncertainty in the return-to-play decision OBJECTIVE There is continuing controversy regarding predictors of poor outcome following mild traumatic brain injury ( mTBI ) . This study aim ed to prospect ively examine the influence of preinjury factors , injury-related factors , and postinjury factors on outcome following mTBI . METHOD Participants were 123 patients with mTBI and 100 trauma patient controls recruited and assessed in the emergency department and followed up 1 week and 3 months postinjury . Outcome was measured in terms of reported postconcussional symptoms . Measures included the  ImPACT Post-Concussional Symptom Scale and cognitive concussion battery , including Attention , Verbal and Visual memory , Processing Speed and Reaction Time modules , pre- and postinjury SF-36 and MINI Psychiatric status ratings , VAS Pain Inventory , Hospital Anxiety and Depression Scale , PTSD Checklist-Specific , and Revised Social Readjustment Scale . RESULTS Presence of mTBI predicted postconcussional symptoms 1 week postinjury , along with being female and premorbid psychiatric history , with elevated HADS anxiety a concurrent indicator . However , at 3 months , preinjury physical or psychiatric problems but not mTBI most strongly predicted continuing symptoms , with concurrent indicators including HADS anxiety , PTSD symptoms , other life stressors and pain . HADS anxiety and age predicted 3-month PCS in the mTBI group , whereas PTSD symptoms and other life stressors were most significant for the controls . Cognitive measures were not predictive of PCS at 1 week or 3 months . CONCLUSIONS Given the evident influence of both premorbid and concurrent psychiatric problems , especially anxiety , on postinjury symptoms , managing the anxiety response in vulnerable individuals with mTBI may be important to minimize ongoing sequelae Background The on-field diagnosis of sports-related concussion ( SRC ) is complicated by the lack of an accurate and objective marker of brain injury . Purpose To compare subject-specific changes in the astroglial protein , S100B , before and after SRC among collegiate and semi-professional contact sport athletes , and compare these changes to differences in S100B before and after non-contact exertion . Study Design Longitudinal cohort study . Methods From 2009–2011 , we performed a prospect i ve study of athletes from Munich , Germany , and Rochester , New York , USA .  Serum S100B was measured in all SRC athletes at pre-season baseline , within 3 hours of injury , and at days 2 , 3 and 7 post-SRC . Among a subset of athletes , S100B was measured after non-contact exertion but before injury . All sample s were collected identically and analyzed using an automated electrochemiluminescent assay to quantify serum S100B levels . Results Forty-six athletes ( 30 Munich , 16 Rochester ) underwent baseline testing . Thirty underwent additional post-exertion S100B testing . Twenty-two athletes ( 16 Rochester , 6 Munich ) sustained a SRC , and 17 had S100B testing within 3 hours post-injury . The mean 3-hour post-SRC S100B was significantly higher than pre-season baseline ( 0.099±0.008 µg/L vs. 0.058±0.006 µg/L , p = 0.0002 ) . Mean post-exertion S100B was not significantly different than the preseason baseline . S100B levels at post-injury days 2 , 3 and 7 were significantly lower than the 3-hour level , and not different than baseline . Both the absolute change and proportional increase in S100B 3-hour post-injury were accurate discriminators of SRC from non-contact exertion without SRC ( AUC 0.772 and 0.904 , respectively ) . A 3-hour post-concussion S100B > 0.122 µg/L and a proportional S100B increase of > 45.9 % over baseline were both 96.7 % specific for SRC . Conclusions Relative and absolute increases in serum S100B can accurately distinguish SRC from sports-related exertion , and may be a useful adjunct to the diagnosis of SRC OBJECTIVES This study of concussed adolescents sought to determine if a computer-based neurocognitive assessment ( Immediate Postconcussion Assessment and Cognitive Test [ ImPACT ] ) performed on patients who present to the emergency department ( ED ) immediately following head injury would correlate with assessment s performed 3 to 10 days postinjury and if ED neurocognitive testing would detect differences in concussion severity that clinical grading scales could not . METHODS A prospect i ve cohort sample of patients 11 to 17 years of age presenting to the ED within 12 hours of a head injury were evaluated using two traditional concussion grading scales and neurocognitive testing .  ED neurocognitive scores were compared to follow-up scores obtained at least 3 days postinjury . Postconcussive symptoms , outcomes , and complications were assessed via telephone follow-up for all subjects . RESULTS Sixty patients completed phone follow-up . Thirty-six patients ( 60 % ) completed follow-up testing a median of 6 days postinjury . Traditional concussion grading did not correlate with neurocognitive deficits detected in the ED or at follow-up . For the neurocognitive domains of verbal memory , processing speed , and reaction time , there was a significant correlation between ED and follow-up scores trending toward clinical improvement . By 2 weeks postinjury , 23 patients ( 41 % ) had not returned to normal activity . At 6 weeks , six patients ( 10 % ) still had not returned to normal activity . CONCLUSIONS Immediate assessment in the ED can predict neurocognitive deficits seen in follow-up and may be potentially useful to individualize management or test therapeutic interventions . Neurocognitive assessment in the ED detected deficits that clinical grading could not and correlated with deficits at follow-up OBJECTIVES To prospect ively examine the relationship of sport-related concussion with depression and neurocognitive performance and symptoms among male and female high school and college athletes . A secondary objective was to explore age and sex differences . DESIGN Pretest , multiple posttest , repeated- measures design . SETTING Laboratory . PARTICIPANTS High school and collegiate athletes ( N=75 ) with a diagnosed concussion . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES  Beck Depression Inventory-II and computerized neurocognitive test battery ( Immediate Post-concussion Assessment and Cognitive Test )  , which includes concussion symptoms ( Post-concussion Symptom Scale ) at baseline and at 2 , 7 , and 14 days postinjury . RESULTS Concussed athletes exhibited significantly higher levels of depression from baseline at 2 days ( P≤.001 ) , 7 days ( P=.006 ) , and 14 days postconcussion ( P=.04 ) . Collegiate athletes demonstrated a significant increase in depression at 14 days postconcussion than did high school athletes ( P=.03 ) . There were no sex differences in depression levels . Neurocognitive decrements at 14 days were supported for reaction time ( P=.001 ) and visual memory ( P=.001 ) . Somatic depression at 7 days postconcussion was related to slower reaction time at 7 days postconcussion . Somatic depression at 14 days postinjury was related to lower visual memory scores at 14 days postinjury . CONCLUSIONS Although not clinical ly significant , athletes experienced increased depression scores up to 14 days after concussion that coincided with neurocognitive decrements in reaction time and visual memory . Somatic depression appears to be most salient with regard to lower neurocognitive performance . Mood assessment s after concussion are warranted to help monitor and enhance recovery Objective : To evaluate a grade d treadmill test for retest reliability ( RTR ) and interrater reliability ( IRR ) in the evaluation of the physiologic effects of symptom exacerbation from concussion . Design : Prospect i ve case series ( RTR ) and blinded rater assessment of 10 actors portraying patients with and without symptom exacerbation ( IRR ) . Setting : University Sports Medicine Concussion Clinic . Participants : For RTR , 21 refractory concussed patients ( 11 athletes and 10 nonathletes ) and 10 healthy subjects ; for IRR , 32 raters representing a variety of health care disciplines . Intervention : For RTR , a Balke protocol treadmill test to symptom exacerbation before and after 2 to 3 weeks . For IRR , video recordings of actors during the treadmill test viewed by raters blinded to condition . Main Outcome Measures : For RTR , agreement of the tests for maximal heart rate ( HR ) , systolic blood pressure , diastolic blood pressure , and rating of perceived exertion . For IRR , presence or absence of symptom exacerbation and the symptom exacerbation HR . Results : Raters achieved a sensitivity of 99 % for identifying actors with symptom exacerbation and a specificity of 89 % for ruling out concussion symptoms and agreed on 304 of 320 observations ( accuracy of 95 % ) . The intraclass correlation coefficient for the symptom exacerbation HR was large at 0.90 ( 95 % confidence interval , 0.78 - 0.98 ) . The treadmill test had good RTR for maximum HR ( intraclass correlation coefficient , 0.79 ) but not for systolic blood pressure , diastolic blood pressure , or rating of perceived exertion . Conclusions : The Balke exercise treadmill protocol has very good IRR and sufficient RTR for identifying patients with symptom exacerbation from concussion The question as to whether mild traumatic brain injury ( mTBI ) results in persisting sequelae over and above those experienced by individuals sustaining general trauma remains controversial . This prospect i ve study aim ed to document outcomes 1 week and 3 months post-injury following mTBI assessed in the emergency department ( ED ) of a major adult trauma center . One hundred and twenty-three patients presenting with uncomplicated mTBI and 100 matched trauma controls completed measures of post-concussive symptoms and cognitive performance ( Immediate Post-Concussion Assessment and Cognitive Testing battery ; ImPACT ) and  pre-injury health-related quality of life ( SF-36 ) in the ED . These measures together with measures of psychiatric status ( the Mini-International Neuropsychiatric Interview [ MINI ] ) pre- and post-injury , the Hospital Anxiety and Depression Scale , Visual Analogue Scale for Pain , Functional Assessment Question naire , and PTSD Checklist-Specific , were re-administered at follow-up . Participants with mTBI showed significantly more severe post-concussive symptoms in the ED and at 1 week post-injury . They performed more poorly than controls on the Visual Memory subtest of the ImPACT at 1 week and 3 months post-injury . Both the mTBI and control groups recovered well physically , and most were employed 3 months post-injury . There were no significant group differences in psychiatric function . However , the group with mild TBI was more likely to report ongoing memory and concentration problems in daily activities . Further investigation of factors associated with these ongoing problems is warranted OBJECT The aim of this study was to determine whether the presence of intracranial pathophysiology on computed tomography ( CT ) scans obtained within 24 hours of  mild traumatic brain injury ( MTBI ) in children adversely affects neuropsychological outcome during the 1st year postinjury . METHODS A prospect i ve longitudinal design was used to examine the neuropsychological outcomes in children ( ages 5 - 15 years ) who had been treated for MTBI , which was defined as a loss of consciousness for up to 30 minutes and a lowest Glasgow Coma Scale ( GCS ) score of 13 - 15 . Exclusion criteria included any preinjury neurological disorder . Outcome assessment s were performed within 2 weeks and at 3 , 6 , and 12 months postinjury . Outcomes were compared between patients with MTBI  whose postinjury CT scans revealed complications of brain pathophysiology ( 32 patients , CMTBI group ) and those with MTBI but without complications ( 48 patients , MTBI group ) . RESULTS Significant interactions confirmed that the pattern of recovery over 12 months after injury differed depending on the intracranial pathology , presence and severity of injuries to body regions other than the head , preinjury attention-deficit hyperactivity disorder ( ADHD ) , and socioeconomic status . Children in the CMTBI group had significantly poorer episodic memory , slower cognitive processing , diminished recovery in managing cognitive interference , and poorer performance in calculating and reading than patients in the MTBI group . Among the patients with mild or no extracranial injury , visuomotor speed was slower in those in the CMTBI group ; and among patients without preinjury ADHD , working memory was worse in those in the CMTBI group . CONCLUSIONS Neuropsychological recovery during the 1st year following MTBI is related to the presence of radiographically detectable intracranial pathology . Children with intracranial pathology on acute CT performed more poorly in several cognitive domains when compared with patients whose CT findings were normal or limited to a linear skull fracture . Depending on the presence of preinjury ADHD and concomitant extracranial injury , working memory and visuomotor speed were also diminished in patients whose CT findings revealed complications following MTBI . Computed tomography within 24 hours postinjury appears to be useful for identifying children with an elevated risk for residual neuropsychological changes OBJECTIVES To examine different timeframes for calculating acute to chronic workload ratio ( ACWR ) and whether this variable is associated with intrinsic injury risk in elite Australian football players . DESIGN Prospect i ve cohort study . METHODS Internal ( session rating of perceived exertion : sRPE ) and external ( GPS distance and sprint distance ) workload and injury data were collected from 70 players from one AFL club over 4 seasons . Various acute ( 1 - 2 weeks ) and chronic ( 3 - 8 weeks ) timeframes were used to calculate ACWRs : these and chronic load categories were then analysed to determine the injury risk in the subsequent month . Poisson regression with robust errors within a generalised estimating equation were utilised to determine incidence rate ratios ( IRR ) . RESULTS Altering acute and /or chronic timeframes did not improve the ability to detect high injury risk conditions above the commonly used 1:4 week ACWR . Twenty-seven ACWR/chronic load combinations were found to be " high risk conditions " ( IRR>1 , p<0.05 ) for injury within 7 days . Most ( 93 % ) of these conditions occurred when chronic load was low or very low and ACWR was either low ( < 0.6 ) or high ( > 1.5 ) . Once a high injury risk condition was entered , the elevated risk persisted for up to 28 days . CONCLUSIONS Injury risk was greatest when chronic load was low and ACWR was either low or high . This heightened risk remained for up to 4 weeks . There was no improvement in the ability to identify high injury risk situations by altering acute or chronic time periods from 1:4 weeks IMPORTANCE Animal models suggest that reduced cerebral blood flow ( CBF ) is one of the most enduring physiological deficits following concussion . Despite this , longitudinal studies documenting serial changes in regional CBF following human concussion have yet to be performed . OBJECTIVE To longitudinally assess the recovery of CBF in a carefully selected sample of collegiate athletes and compare time course of CBF recovery with that of cognitive and behavioral symptoms . DESIGN , SETTING , AND PARTICIPANTS A cohort of collegiate football athletes ( N = 44 ) participated in this mixed longitudinal and cross-sectional study at a private research institute specializing in neuroimaging between March 2012 and December 2013 .  Serial imaging occurred approximately 1 day , 1 week , and 1 month postconcussion for a subset of participants ( n = 17 ) . All athletes reported no premorbid mood disorders , anxiety disorders , substance abuse , or alcohol abuse . MAIN OUTCOMES AND MEASURES  Arterial spin labeling magnetic resonance imaging  was used to collect voxelwise relative CBF at each visit . Neuropsychiatric evaluations and a brief cognitive screen  were also performed at all 3 points . Clinicians trained in sports medicine provided an independent measure of real-world concussion outcome ( ie , number of days withheld from competition ) . RESULTS The results indicated both cognitive ( simple reaction time ) and neuropsychiatric symptoms at 1 day postinjury that resolved at either 1 week ( cognitive ; P < .005 ) or 1 month ( neuropsychiatric ; P < .005 ) postinjury . Imaging data suggested both cross-sectional ( ie , healthy vs concussed athletes ; P < .05 ) and longitudinal ( 1 day and 1 week vs 1 month postinjury ; P < .001 ) evidence of CBF recovery in the right insular and superior temporal cortex . Importantly , CBF in the dorsal midinsular cortex was both decreased at 1 month postconcussion in slower-to-recover athletes ( t11 = 3.45 ; P = .005 ) and was inversely related to the magnitude of initial psychiatric symptoms ( Hamilton Depression Scale : r = -0.64 , P = .02 ; Hamilton Anxiety Scale : r = -0.56 , P = .046 ) , suggesting a potential prognostic indication for CBF as a biomarker . CONCLUSIONS AND RELEVANCE To our knowledge , these results provide the first prospect i ve evidence of reduced CBF in human concussion and subsequent recovery . The resolution of CBF abnormalities closely mirrors previous reports from the animal literature and show real-world validity for predicting outcome following concussion
Robust RT deficits were observed acutely following concussion .
Minimal magnitude differences were noted when comparing between- and within-subject effects , suggesting that pre-injury baselines may not add clinical value in determining post-injury RT impairment .
RT deficits persisted up till the intermediate-term ( 21–59 days post-injury ) timeframe and indicate lingering deficits exist .
Mean effect size differences were observed between RT measure types and computerized neurocognitive testing platforms ; however , all categories displayed negative effects consistent with impaired RT following concussion .
Reaction time ( RT ) deficits are reported following concussion , but it is unknown when these deficits normalize to pre-injury status .
It is also unclear how factors such as RT measurement technique and participant characteristics influence post-concussion RT .
The purpose of this systematic review and meta- analysis was to ( 1 ) characterize acute post-concussion ( 0–3 days ) RT impairments , ( 2 ) examine RT recovery over time , and ( 3 ) explore moderating factors related to acute RT impairment following concussion .