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Synopsis of the National Football League Player Health and Safety Meeting: Chicago, Illinois, June 19, 2007

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... At the time of the above referenced studies of Pellman et al. (2004 Pellman et al. ( , 2006), neuropsychological testing was a " recommended " but not a mandatory requirement in the NFL. On June 19, 2007, the NFL held a " Health and Safety " meeting in Chicago, and was attended by NFL team physicians, certified athletic trainers, other team medical personnel, NFL League Office representatives, and members from the NFL Players Association (Cason, Viano, & Pellman, 2008). In addition, expert presenters from the fields of neurology, neurosurgery, neuropsychology, neuroradiology, sports medicine, biomechanical engineering, and athletic training participated in the discussion of mild traumatic brain injury (concussion) in the NFL. ...
... At the time of the above referenced studies of Pellman et al. (2004 Pellman et al. ( , 2006), neuropsychological testing was a " recommended " but not a mandatory requirement in the NFL. On June 19, 2007, the NFL held a " Health and Safety " meeting in Chicago, and was attended by NFL team physicians, certified athletic trainers, other team medical personnel, NFL League Office representatives, and members from the NFL Players Association (Cason, Viano, & Pellman, 2008). In addition, expert presenters from the fields of neurology, neurosurgery, neuropsychology, neuroradiology, sports medicine, biomechanical engineering, and athletic training participated in the discussion of mild traumatic brain injury (concussion) in the NFL. ...
... The type of neuropsychological testing (i.e., paper and pencil or computerized) was not delineated, but it has been reported that at least 29 of the 32 NFL teams now use ImPACT (Lovell, personal communication, April 28, 2008). Efforts at educating athletes and their families about signs and symptoms of concussion also was mandated (see Cason et al., 2008, for details of the educational materials). The purposes of our study are to present preliminary ImPACT normative data on a large group of NFL athletes, and to assess the potential effects of various demographic and biopsychosocial variables on baseline ImPACT scores. ...
Article
The use of neurocognitive testing in the assessment of professional athletes sustaining sports-related concussions has become widespread over the past decade. Baseline neurocognitive testing is now a requirement for athletes in the National Football League (NFL). We present preliminary normative data on a computer based neurocognitive test (Immediate Post Concussion Assessment and Cognitive Testing; ImPACT) for 159 NFL athletes. Also included are summary data on basic biopsychosocial characteristics, including medical, psychiatric, chemical dependency, concussion, learning disability/attention deficit disorder, and symptom variables, and the relevance of each to baseline neurocognitive test scores.
... Table 1 shows an example of a standardized list that can be used by the physician. 5 This list can be customized as the physician gains experience. The signs and symptoms of MTBI listed in Table 2 include the frequency of occurrence during a 6-year period in NFL players. ...
... During the past 20 years, several organizations and individuals have promulgated guidelines intended to help team physicians in making RTP decisions. [1][2][3][4][5][27][28][29] These have usually started by grading the severity of concussions according to criteria, including presence or absence of LOC and amnesia and how long it takes for the initial symptoms of MTBI to resolve. Some guidelines also consider the number of prior MTBIs sustained by the athlete. ...
... For example, although recent clinical studies indicate that LOC is not the only factor influencing time to recovery, they also demonstrate that LOC is one of the significant risk factors for the development of post concussion syndrome, leading many experts in the field to agree with the guidelines that players with observed LOC on the day of the concussion are not good candidates for RTP on the day of the concussion. 5,6,12 In addition, modern concussion management and the guidelines are in agreement that injured athletes should only be considered for return to play when the athlete is completely asymptomatic at rest and with exertion and has a normal neurological examination, including mental status. 5,6,26 This does not mean that every athlete who meets these criteria should automatically be medically cleared to return to play; it means that athletes who are symptomatic and/or have abnormalities on neurological examination should not be considered for return to play at that time. ...
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The evaluation and management of concussion (ie, mild traumatic brain injury) in athletes is typically the responsibility of team or school physicians. The great majority of these physicians are orthopedists, family physicians, internists, pediatricians, or sports medicine specialists who have not had specialty training in neurology or neurosurgery. The evaluation and management of mild traumatic brain injury is primarily guided by a neurological clinical evaluation of the patient. The purpose of this article is to review relevant aspects of the neurological history and examination as well as the neurological approach to the concussed athlete.
... High strain-rates generated by such waves were found to have differential pathological effect on the anisotropic structures of the brain, especially white matter tracts where directionality is significant [81]. The propagation of stresses through the skull were compared in blast situations and in cases of impacts in contact sports such as in the National Football League [82,83], and a quantitative relationship was established in terms of the differences in the orders of magnitude of the stresses. ...
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Blast injuries affect millions of lives across the globe due to its traumatic after effects on the brain and the whole body. To date, military grade armour materials are designed to mitigate ballistic and shrapnel attacks but are less effective in resisting blast impacts. In order to improve blast absorption characteristics of armours, the first key step is thoroughly understands the effects of blasts on the human body itself. In the last decade, a plethora of experimental and computational work has been carried out to investigate the mechanics and pathophysiology of Traumatic Brain Injury (TBI). However, very few attempts have been made so far to study the effect of blasts on the various other parts of the body such as the sensory organs (eyes and ears), nervous system, thorax, extremities, internal organs (such as the lungs) and the skeletal system. While an experimental evaluation of blast effects on such physiological systems is difficult, developing finite element (FE) models could allow the recreation of realistic blast scenarios on full scale human models and simulate the effects. The current article reviews the state-of-the-art in computational research in blast induced whole-body injury modelling, which would not only help in identifying the areas in which further research is required, but would also be indispensable for understanding body location specific armour design criteria for improved blast injury mitigation.
... NFL team physicians clear a player for return to play after he is asymptomatic and has a normal neurologic examination. 3,4,11 Return immediately. The player returns after the team physician's evaluation demonstrates that he is asymptomatic and has a normal neurologic examination. ...
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Positions, signs, symptoms, and medical management of National Football League players with concussions involving 7 or more days out (7+) from play were compared for two 6-year study periods (2002-2007 vs 1996-2001). More players were held out 7+ days in the 2002-2007 period without significant difference in concussion signs and symptoms. Cohort. From 1996 through 2007, National Football League team physicians reported concussion signs and symptoms, medical action taken, and follow-up management. During the 2002-2007 period, 143 (16.7%) and 33 (3.86%) concussed players were out 7+ days and 21+ days, respectively, compared with 73 (8.2%) and 7 (0.79%) in the 1996-2001 period, a significant difference (z = 5.39, P < .01). The positions with the highest fraction of 7+ days out were the quarterback (24.5% vs 16.1%), linebacker (19.7% vs 4.6%), and wide receiver (19.5% vs 8.2%) in the later versus earlier period. The player positions with the highest odds for being out 7+ days were quarterback (odds ratio = 1.80 vs 4.02), linebacker (odds ratio = 1.28 vs 0.65), and wide receiver (odds ratio = 1.25 vs 1.15). The highest incidence of 7+ days out occurred after passing plays (32.2% vs 37.0%), followed by kickoffs (18.9% vs 21.9%). The majority of players with 7+ days out were removed from the game on the day of injury (74.8% vs 72.6%); a smaller fraction were returned to play on the day of injury in the later 6 years (3.5% vs 6.8%). The positions with the highest odds for being out 7+ days with concussion were quarterbacks, linebackers, and wide receivers. In the more recent 6-year period, more players were managed conservatively by being held out 7+ days, even though the signs and symptoms of their concussions were similar to those in the earlier period.
... Before the 2007 season (the last season of the second 6-year period reported here), the Mild Traumatic Brain Injury Committee reaffirmed to all NFL team physicians that players with witnessed LOC following concussion should not be cleared to RTP on the day of injury. 2 However, the previous studies have not defined brief LOC as a risk factor for concussion severity, so it is possible that this confounds the data in the second 6 years, depending on how many of the 57 LOC concussions occurred after the ruling change. Review of data indicates that this has been the practice of NFL team physicians for a number of years. ...
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Concussion in the National Football League (NFL) remains an important issue. An initial description of the injury epidemiology involved 6 years from 1996 to 2001. The increased attention to concussions may have resulted in team physicians being more conservative in treating players in recent years. Two consecutive 6-year periods (1996-2001 and 2002-2007) were compared to determine changes in the circumstances associated with the injury, the patterns of signs and symptoms, and the players' time loss from participation in the NFL. During 2002-2007, concussions were recorded by NFL team physicians and athletic trainers using the same standardized reporting form used from 1996 to 2001. Player position, type of play, concussion signs and symptoms, loss of consciousness, and medical action taken were recorded. There were 0.38 documented concussions per NFL game in 2002-2007-7.6% lower than the 0.42 in the earlier period (1996-2001). The injury rate was lower in quarterbacks and wide receivers but significantly higher in tight ends during the second 6 years. The most frequent symptoms were headaches and dizziness; the most common signs were problems with information processing and immediate recall. During 2002-2007, a significantly lower fraction of concussed players returned to the same game, and more were removed from play. Most concussed players (83.5%) returned to play in < 7 days; the percentage decreased to 57.4% with loss of consciousness. The number of players returning in < 7 days was 8% lower during 2002-2007 and 25% lower for those with loss of consciousness. The most recent 6 years of NFL concussion data show a remarkable similarity to the earlier period. However, there was a significant decrease in the percentage of players returning to the same game, and players were held out of play longer. There was a more conservative management of concussion in NFL players from 2002 to 2007 even though the clinical signs and symptoms remained similar to the earlier 6-year period.
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The objective of this study was to systematically review clinical studies examining biofluid biomarkers of brain injury for concussion in athletes. Data Sources included PubMed®, MEDLINE® and the Cochrane Database from 1966 to October 2013. Studies were included if they recruited athletes participating in organized sports who experienced concussion or head injury during a sports-related activity and had brain injury biomarkers measured. Acceptable research designs included experimental, observational, and case control studies. Review articles, opinion papers and editorials were excluded. After title and abstract screening of potential articles, full texts were independently reviewed to identify articles that met inclusion criteria. A composite evidentiary table was then constructed and documented the study title, design, population, methods, sample size, outcome measures, and results. The search identified fifty two publications, of which thirteen were selected and critically reviewed. All of the included studies were prospective and were published either in or after the year 2000. Sports included boxing (6 studies), soccer (5 studies), running/jogging (2 studies), hockey (1 study), basketball (1 study), cycling (1 study), and swimming (1 study). The majority of studies (92%) had fewer than 100 patients. Three studies (23%) evaluated biomarkers in cerebrospinal fluid (CSF), one in both serum and CSF, and 10 (77%) in serum exclusively. There were eleven different biomarkers assessed including S100β, GFAP, NSE, tau, NFL, amyloid beta, BDNF, CK and h-FABP, prolactin, cortisol, and albumin. A handful of biomarkers showed correlation with number of hits to the head (soccer), acceleration/deceleration forces (jumps, collisions, and falls), post-concussive symptoms, trauma to the body versus the head, and dynamics of different sports. Although there are no validated biomarkers for concussion yet, there is potential for biomarkers to provide diagnostic, prognostic, and monitoring information post-injury. They could also be combined with neuroimaging to assess injury evolution and recovery.
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Linear impactor tests were conducted on football helmets from the 1970s-1980s to complement recently reported tests on 1990 s and 2010 s helmets. Helmets were placed on the Hybrid III head with an array of accelerometers to determine translational and rotational acceleration. Impacts were at four sites on the helmet shell at 3.6-11.2 m/s. The four generations of helmets show a continuous improvement in response from bare head impacts in terms of Head Injury Criterion (HIC), peak head acceleration and peak rotational acceleration. Helmets of 2010 s weigh 1.95 ± 0.2 kg and are 2.7 times heavier than 1970s designs. They are also 4.3 cm longer, 7.6 cm higher, and 4.9 cm wider. The extra size and weight allow the use of energy absorbing padding that lowers forces in helmet impacts. For frontal impacts at 7.4 m/s, the four best performing 2010 s helmets have HIC of 148 ± 23 compared to 179 ± 42 for the 1990 s baseline, 231 ± 27 for the 1980s, 253 ± 22 for the 1970s helmets, and 354 ± 3 for the bare head. The additional size and padding of the best 2010 s helmets provide superior attenuation of impact forces in normal play and in conditions associated with concussion than helmets of the 1970s-1990 s.
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The purpose of this preliminary study was to investigate possible differences among a group of fencers and a group of swimmers, in the visual memory task and the spatial anticipation task. 15 national level fencers (aged between 16 to 23 years) and 15 swimmers of a competitive swimming club (aged between 15 to 22 years), were studied. The Brixton Spatial Anticipation Test (BSAT) was used as a measure of executive functioning. The second test was the Visual Patterns Test (VPT), which measured visual short-term memory. The Digit Span subtest of the Wechsler Adult Intelligence Scale-III (WAIS) was also included as an estimate of general intelligence. There was a significant difference between fencers & swimmers in the BSAT, (F=5.261, p<0.030), while the analysis of the VPT test scores showed no significant differences among groups (F=0.325 p<=0.573). In conclusion, fencers showed no better performance on visual memory, while they were superior in rule detection, comparing to swimmers. The long training fencing program, may greatly affects the speed of constitute information process as attributes of the decision making speed in national level fencers.
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We considered Dr Mayers' report of his experiences with concussed athletes and his brief review of recent, basic science research studies on head injury.1 However, we respectfully disagree with the conclusion that “a postconcussion return-to-play (RTP) interval of at least 4 weeks is imperative.”1 In essence, Dr Mayers concludes that since current clinical practices regarding RTP are not based on scientific evidence and because some basic laboratory research suggests that changes in the brain following concussion persist for at least 4 weeks following injury, clinicians must revise their current practice by mandating at least a 4-week RTP interval for all concussed athletes. We believe that the foundation for Dr Mayers' conclusion is flawed owing to a misinterpretation and misapplication of basic research results to the clinical sphere and his omission of the current state of clinical research on sports-related concussions.
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OBJECTIVE Cerebral concussion is common in collision sports such as football, yet the chronic neurological effects of recurrent concussion are not well understood. The purpose of our study was to investigate the association between previous head injury and the likelihood of developing mild cognitive impairment (MCI) and Alzheimer's disease in a unique group of retired professional football players with previous head injury exposure. METHODS A general health questionnaire was completed by 2552 retired professional football players with an average age of 53.8 (±13.4) years and an average professional football playing career of 6.6 (± 3.6) years. A second questionnaire focusing on memory and issues related to MCI was then completed by a subset of 758 retired professional football players (≥50 yr of age). Results on MCI were then cross-tabulated with results from the original health questionnaire for this subset of older retirees. RESULTS Of the former players, 61% sustained at least one concussion during their professional football career, and 24% sustained three or more concussions. Statistical analysis of the data identified an association between recurrent concussion and clinically diagnosed MCI (χ² = 7.82, df = 2, P = 0.02) and self-reported significant memory impairments (χ² = 19.75, df = 2, P = 0.001). Retired players with three or more reported concussions had a fivefold prevalence of MCI diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion. Although there was not an association between recurrent concussion and Alzheimer's disease, we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population CONCLUSION Our findings suggest that the onset of dementia-related syndromes may be initiated by repetitive cerebral concussions in professional football players.
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Objective: Concussion in professional football was studied with respect to impact types and injury biomechanics. A combination of video surveillance and laboratory reconstruction of game impacts was used to evaluate concussion biomechanics. Methods: Between 1996 and 2001, videotapes of concussions and significant head impacts were collected from National Football League games. There were clear views of the direction and location of the helmet impact for 182 cases. In 31 cases, the speed of impact could be determined with analysis of multiple videos. Those cases were reconstructed in laboratory tests using helmeted Hybrid III dummies and the same impact velocity, direction, and head kinematics as in the game. Translational and rotational accelerations were measured, to define concussion biomechanics. Several studies were performed to ensure the accuracy and reproducibility of the video analysis and laboratory methods used. Results: Concussed players experienced head impacts of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 miles/h). There was a rapid change in head velocity of 7.2 +/- 1.8 m/s (16.1 +/- 4.0 miles/h), which was significantly greater than that for uninjured struck players (5.0 +/- 1.1 m/s, 11.2 +/- 2.5 miles/h; t = 2.9, P < 0.005) or striking players (4.0 +/- 1.2 m/s, 8.9 +/- 2.7 miles/h; t = 7.6, P < 0.001). The peak head acceleration in concussion was 98 +/- 28 g with a 15-millisecond half-sine duration, which was statistically greater than the 60 +/- 24 g for uninjured struck players (t = 3.1, P < 0.005). Concussion was primarily related to translational acceleration resulting from impacts on the facemask or side, or falls on the back of the helmet. Concussion could be assessed with the severity index or head injury criterion (the conventional measures of head injury risk). Nominal tolerance levels for concussion were a severity index of 300 and a head injury criterion of 250. Conclusion: Concussion occurs with considerable head impact velocity and velocity changes in professional football. Current National Operating Committee on Standards for Athletic Equipment standards primarily address impacts to the periphery and crown of the helmet, whereas players are experiencing injuries in impacts to the facemask, side, and back of the helmet. New tests are needed to assess the performance of helmets in reducing concussion risks involving high-velocity and long-duration injury biomechanics.
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National Football League game video was analyzed for the typical locations of severe helmet impacts in professional football. By use of selected cases that were reconstructed in laboratory tests and reported previously, the magnitude and direction of force causing concussion was determined for these locations. Multiple video views were obtained for 182 severe helmet impacts that occurred between 1996 and 2001. From a top view, the helmet was divided into 45-degree quadrants with 0 degrees eyes forward. From a side view, it was divided into seven equal levels, four (+Q1 to +Q4) above the head center of gravity and three below (-Q1 to -Q3). The initial helmet contact was located in these regions. Thirty-one impacts were reconstructed with helmeted Hybrid III dummies involving 25 concussions. Measurement of head translational and rotational acceleration was used to determine the average and +/-1 standard deviation in responses, with impacts reflected to the right side. From video, the majority (71%) of impact is to the helmet shell primarily from a striking player's helmet, arm, or shoulder pad to the side (45-135 degrees) or from ground contact to the back (135-180 degrees). Most impacts were high on the helmet at +Q2 to +Q4. The remainder (29%) were primarily from helmet contact on the facemask at an oblique frontal angle (0-45 degrees) and -Q3 to +Q1 height. From reconstructions, concussion occurred with the lowest peak head acceleration in facemask impacts at 78 +/- 18 g versus an average 107 to 117 g for impacts on other quadrants (t = 2.90, P < 0.005). There was a significantly higher head acceleration for concussed versus nonconcussed players (t = 2.85, P < 0.05). The vector of peak force was essentially horizontal for facemask impacts and downward at 12 to 27 degrees for impacts to the helmet side and back. Concussion in professional football involves four typical conditions, as follows: A, 0- to 45-degree quadrant, -Q3 to +Q3 level, peak force 49 +/- 18 degrees from front and horizontal; B, 45- to 90-degree quadrant, -Q2 to +Q3 level, peak force 73 +/- 12 degrees and horizontal; C, 90- to 135-degree quadrant, +Q1 to +Q4 level, peak force 97 +/- 9 degrees and 12 degrees downward; and D, 135- to 180-degree quadrant, +Q1 to +Q4 level, peak force 157 +/- 1 degrees and 27 degrees downward. Concussed players averaged 3.6 +/- 2.7 initial signs and symptoms. The most common were headaches, dizziness, immediate recall problems, and difficulty with information processing. The location, direction, and severity of helmet impacts causing concussion in the National Football League have been defined from analysis of game video and laboratory reconstruction. These conditions define the circumstances in which helmets need to reduce head injury risks in professional football.
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A 6-year study was performed to determine the circumstances, causes, and outcomes of concussions in the National Football League. Between 1996 and 2001, the epidemiological features of concussions were recorded by National Football League teams with a standardized reporting form. Symptoms were reported and grouped as general symptoms, cranial nerve symptoms, memory or cognitive problems, somatic complaints, and loss of consciousness. The medical actions taken were recorded. In total, 787 game-related cases were reported, with information on the players involved, type of helmet impact, symptoms, medical actions, and days lost. Concussion risks were calculated according to player game positions. There were 0.41 concussions per National Football League game. The relative risk was highest for quarterbacks (1.62 concussions/100 game-positions), followed by wide receivers (1.23 concussions/100 game-positions), tight ends (0.94 concussion/100 game-positions), and defensive secondaries (0.93 concussion/100 game-positions). The majority of concussions (67.7%) involved impact by another player's helmet. The remainder involved impact by other body regions of the striking player (20.9%) or ground contact (11.4%). The three most common symptoms of mild traumatic brain injury were headaches (55.0%), dizziness (41.8%), and blurred vision (16.3%). The most common signs noted in physical examinations were problems with immediate recall (25.5%), retrograde amnesia (18.0%), and information-processing problems (17.5%). In 58 of the reported cases (9.3%), the players lost consciousness; 19 players (2.4%) were hospitalized. A total of 92% of concussed players returned to practice in less than 7 days, but that value decreased to 69% with unconsciousness. The professional football players most vulnerable to concussions are quarterbacks, wide receivers, and defensive secondaries. Concussions involved 2.74 symptoms/injury, and players were generally removed from the game. More than one-half of the players returned to play within 1 day, and symptoms resolved in a short time in the vast majority of cases.
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The National Football League (NFL) neuropsychological testing program is reviewed, and neuropsychological test data are presented on various samples of NFL athletes who sustained concussion (mild traumatic brain injury, MTBI). This study evaluated post-MTBI neuropsychological testing of NFL players from 1996 to 2001. All athletes completed a standardized battery of neuropsychological tests and underwent postinjury neuropsychological testing within a few days after concussion. Test scores were compared with baselines using analysis of variance for athletes having on-field memory dysfunction, three or more concussions, or 7+ days out from practice and play. The MTBI group did not display significant neuropsychological dysfunction relative to baseline scores within a few days of injury. However, a subsample of the injured athletes who displayed on-field memory dysfunction performed significantly more poorly on two of the memory tests. The neuropsychological test results of a group of athletes with a history of three or more MTBIs did not differ significantly compared with a group who had fewer than three concussions or compared with league-wide normative data. The neuropsychological performance of athletes who were out from full participation 7+ days was not significantly different from the group who returned to play within 7 days or the norms. Neuropsychological testing is used within the overall medical evaluation and care of NFL athletes. Players who experience MTBI generally demonstrate rapid recovery of neuropsychological performance, although poorer neuropsychological test results were related to on-field memory dysfunction. NFL players did not demonstrate evidence of neurocognitive decline after multiple (three or more) MTBIs or in those players out 7+ days. The data show that MTBI in this population is characterized by a rapid return of neuropsychological function in the days after injury.
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Impacts causing concussion in professional football were simulated in laboratory tests to determine collision mechanics. This study focuses on the biomechanics of concussion in the struck player. Twenty-five helmet impacts were reconstructed using Hybrid III dummies. Head impact velocity, direction, and helmet kinematics-matched game video. Translational and rotational accelerations were measured in both players' heads; 6-axis upper neck responses were measured in all striking and five struck players. Head kinematics and biomechanics were determined for concussed players. Head displacement, rotation, and neck loads were determined because finite element analysis showed maximum strains occurring in the midbrain after the high impact forces. A model was developed of the helmet impact to study the influence of neck strength and other parameters on head responses. The impact response of the concussed player's head includes peak accelerations of 94 +/- 28 g and 6432 +/- 1813 r/s2, and velocity changes of 7.2 +/- 1.8 m/s and 34.8 +/- 15.2 r/s. Near the end of impact (10 ms), head movement is only 20.2 +/- 6.8 mm and 6.9 +/- 2.5 degrees. After impact, there is rapid head displacement involving a fourfold increase to 87.6 +/- 21.2 mm and 29.9 +/- 9.5 degrees with neck tension and bending at 20 ms. Impacts to the front of the helmet, the source of the majority of National Football League concussions, cause rotation primarily around the z axis (superior-inferior axis) because the force is forward of the neck centerline. This twists the head to the right or left an average of 17.6 +/- 12.7 degrees, causing a moment of 17.7 +/- 3.3 Nm and neck tension of 1704 +/- 432 N at 20 ms. The head injury criterion correlates with concussion risk and is proportional to deltaV(4)/d(1.5) for half-sine acceleration. Stronger necks reduce head acceleration, deltaV, and displacement. Even relatively small reductions in deltaV have a large effect on head injury criterion that may reduce concussion risks because changes in deltaV change head injury criterion through the 4th power. This study addresses head responses causing concussion in National Football League players. Although efforts are underway to reduce impact acceleration through helmet padding, further study is needed of head kinematics after impact and their contribution to concussion, including rapid head displacement, z-axis rotation, and neck tension up to the time of maximum strain in the midbrain. Neck strength influences head deltaV and head injury criterion and may help explain different concussion risks in professional and youth athletes, women, and children.
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A 6-year study was conducted to determine the signs, symptoms, and management of repeat concussion in National Football League players. From 1996 to 2001, concussions were reported by 30 National Football League teams using a standardized reporting form filled out by team physicians with input from athletic trainers. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Medical actions taken and management were recorded. Data were captured for 887 concussions in practices and games involving 650 players. A total of 160 players experienced repeat injury, with 51 having three or more concussions during the study period. The median time between injuries was 374.5 days, with only six concussions occurring within 2 weeks of the initial injury. Repeat concussions were more prevalent in the secondary (16.9%), the kick unit on special teams (16.3%), and wide receivers (12.5%). The ball return carrier on special teams (odds ratio [OR] = 2.08, P = not significant) and quarterbacks (OR = 1.92, P < 0.1) had elevated odds for repeat injury, followed by the tight end (OR = 1.24, P = not significant) and linebackers (OR = 1.22, P = not significant). There were similar signs and symptoms with single and repeat concussion, except for a higher prevalence of somatic complaints in players on their repeat concussions compared with their first concussion (27.5% versus 18.8%, P < 0.05). More than 90% of players were managed by rest, and 57.5% of those with second injuries returned to play within a day. Players with three or more concussions had signs, symptoms, and treatment similar to those with only a single injury. The most vulnerable players for repeat concussion in professional football are the ball return carrier on special teams and quarterbacks. Single and repeat concussions are managed conservatively with rest, and most players return quickly to play.
Article
A 6-year study was conducted to determine the signs, symptoms, and outcome of players who were concussed and either returned immediately or were rested and returned to the same game in the National Football League (NFL). From 1996 to 2001, concussions were recorded by NFL teams by use of a special standardized reporting form filled out by team physicians. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Action taken after concussion was recorded for 887 patients. There were 135 players (15.2%) who returned immediately and 304 (34.3%) who rested and returned to the same game after concussion. There were few differences by player position or team activity about the injury or action taken. However, the mean number of signs and symptoms progressively increased from those who returned immediately (1.52), rested and returned to play (2.07), were removed from play (3.51), or were hospitalized (6.55). Immediate recall problems (odds ratio [OR], 1.93; confidence interval [CI], 1.26-2.94), memory problems (OR, 1.52; CI, 1.06-2.19), and the number of signs and symptoms (OR, 1.39; CI, 1.25-1.55) were predictive of removal from play or hospitalization. There was no statistical association between return to play in the same game and a subsequent concussion or a more serious concussion involving 7+ days out. Players who are concussed and return to the same game have fewer initial signs and symptoms than those removed from play. Return to play does not involve a significant risk of a second injury either in the same game or during the season. The current decision-making of NFL team physicians seems appropriate for return to the game after a concussion, when the player has become asymptomatic and does not have memory or cognitive problems.
Article
Concussive impacts in professional football were simulated in laboratory tests to determine the collision mechanics resulting in injury to the struck player and the biomechanics of the striking players, who were not concussed or neck-injured in the tackle. Twenty-seven helmet-to-helmet collisions were reconstructed in laboratory tests using Hybrid III dummies. The head impact velocity, direction, and kinematics matched game video. Translational and rotational head accelerations and six-axis upper neck loads and moments were used to evaluate how the striking player delivered the concussive blow. The neck injury criterion, Nij, was calculated to assess neck injury risks in the striking player. The time-averaged impact force reached 6372 +/- 2486 N at 7.2 milliseconds because of 46.8 +/- 21.7 g head acceleration and 3624 +/- 1729 N neck compression force in the striking player. Fifty-seven percent of the load was contributed by neck compression. The striking players had their heads down and lined up the impact axis through their necks and torsos. This allowed momentum transfer with minimal neck bending and increased the effective mass of the striking player to 1.67 times that of the struck player at peak load. The impact caused 94.3 +/- 27.5 g head acceleration in the concussed players and 67.9 +/- 14.5 g without concussion (t = 2.06, df = 25, P = 0.025). The striking player's Nij was greater than tolerance in 9 of 27 cases by exceeding the 4000 N neck compression limit. For these cases, the average neck compression force was 6631 +/- 977 N (range, 5210-8194 N). Nij was 1.25 +/- 0.16 for eight cases above the tolerance Nij = 1.0. In the NFL, striking players line up their heads, necks, and torsos to deliver maximum force to the other player in helmet-to-helmet impacts. The concussive force is from acceleration of the striking player's head and torso load through the neck. Even though neck responses exceeded tolerances, no striking player experienced neck injury or concussion. A head-up stance at impact would reduce the torso inertial load in the collision and the risk of concussion in the struck player.
Article
We present the results of the autopsy of a retired professional football player that revealed neuropathological changes consistent with long-term repetitive concussive brain injury. This case draws attention to the need for further studies in the cohort of retired National Football League players to elucidate the neuropathological sequelae of repeated mild traumatic brain injury in professional football. The patient's premortem medical history included symptoms of cognitive impairment, a mood disorder, and parkinsonian symptoms. There was no family history of Alzheimer's disease or any other head trauma outside football. A complete autopsy with a comprehensive neuropathological examination was performed on the retired National Football League player approximately 12 years after retirement. He died suddenly as a result of coronary atherosclerotic disease. Studies included determination of apolipoprotein E genotype. Autopsy confirmed the presence of coronary atherosclerotic disease with dilated cardiomyopathy. The brain demonstrated no cortical atrophy, cortical contusion, hemorrhage, or infarcts. The substantia nigra revealed mild pallor with mild dropout of pigmented neurons. There was mild neuronal dropout in the frontal, parietal, and temporal neocortex. Chronic traumatic encephalopathy was evident with many diffuse amyloid plaques as well as sparse neurofibrillary tangles and tau-positive neuritic threads in neocortical areas. There were no neurofibrillary tangles or neuropil threads in the hippocampus or entorhinal cortex. Lewy bodies were absent. The apolipoprotein E genotype was E3/E3. This case highlights potential long-term neurodegenerative outcomes in retired professional National Football League players subjected to repeated mild traumatic brain injury. The prevalence and pathoetiological mechanisms of these possible adverse long-term outcomes and their relation to duration of years of playing football have not been sufficiently studied. We recommend comprehensive clinical and forensic approaches to understand and further elucidate this emergent professional sport hazard.
Article
Cerebral concussion is common in collision sports such as football, yet the chronic neurological effects of recurrent concussion are not well understood. The purpose of our study was to investigate the association between previous head injury and the likelihood of developing mild cognitive impairment (MCI) and Alzheimer's disease in a unique group of retired professional football players with previous head injury exposure. A general health questionnaire was completed by 2552 retired professional football players with an average age of 53.8 (+/-13.4) years and an average professional football playing career of 6.6 (+/- 3.6) years. A second questionnaire focusing on memory and issues related to MCI was then completed by a subset of 758 retired professional football players (> or = 50 yr of age). Results on MCI were then cross-tabulated with results from the original health questionnaire for this subset of older retirees. Of the former players, 61% sustained at least one concussion during their professional football career, and 24% sustained three or more concussions. Statistical analysis of the data identified an association between recurrent concussion and clinically diagnosed MCI (chi = 7.82, df = 2, P = 0.02) and self-reported significant memory impairments (chi = 19.75, df = 2, P = 0.001). Retired players with three or more reported concussions had a fivefold prevalence of MCI diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion. Although there was not an association between recurrent concussion and Alzheimer's disease, we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population. Our findings suggest that the onset of dementia-related syndromes may be initiated by repetitive cerebral concussions in professional football players.
Article
National Football League (NFL) concussions occur at an impact velocity of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 mph) oblique on the facemask, side, and back of the helmet. There is a need for new testing to evaluate helmet performance for impacts causing concussion. This study provides background on new testing methods that form a basis for supplemental National Operating Committee on Standards for Athletic Equipment (NOCSAE) helmet standards. First, pendulum impacts were used to simulate 7.4 and 9.3 m/s impacts causing concussion in NFL players. An instrumented Hybrid III head was helmeted and supported on the neck, which was fixed to a sliding table for frontal and lateral impacts. Second, a linear pneumatic impactor was used to evaluate helmets at 9.3 m/s and an elite impact condition at 11.2 m/s. The upper torso of the Hybrid III dummy was used. It allowed interactions with shoulder pads and other equipment. The severity of the head responses was measured by a severity index, translational and rotational acceleration, and other biomechanical responses. High-speed videos of the helmet kinematics were also recorded. The tests were evaluated for their similarity to conditions causing NFL concussions. Finally, a new linear impactor was developed for use by NOCSAE. The pendulum test closely simulated the conditions causing concussion in NFL players. Newer helmet designs and padding reduced the risk of concussion in 7.4 and 9.3 m/s impacts oblique on the facemask and lateral on the helmet shell. The linear impactor provided a broader speed range for helmet testing and more interactions with safety equipment. NOCSAE has prepared a draft supplemental standard for the 7.4 and 9.3 m/s impacts using a newly designed pneumatic impactor. No helmet designs currently address the elite impact condition at 11.2 m/s, as padding bottoms out and head responses dramatically increase. The proposed NOCSAE standard is the first to address helmet performance in reducing concussion risks in football. Helmet performance has improved with thicker padding and fuller coverage by the shell. However, there remains a challenge for innovative designs that reduce risks in the 11.2 m/s elite impact condition.
Article
Acute recovery from concussion (mild traumatic brain injury) is assessed in samples of NFL and high school athletes evaluated within days of injury. All athletes were evaluated within days of injury using a computer-based neuropsychological test and symptom inventory protocol. Test performance was compared to preinjury baseline levels of a similar but not identical group of athletes who had undergone preseason testing. Statistical analyses were completed using Multivariate Analysis of Variance (MANOVA). NFL athletes demonstrated a rapid neuropsychological recovery. As a group, NFL athletes returned to baseline performance in a week with the majority of athletes having normal performance two days after injury. High school athletes demonstrated a slower recovery than NFL athletes. Computer-based neuropsychological testing was used within the overall medical evaluation and care of NFL athletes. As found in a prior study using more traditional neuropsychological testing, NFL players did not demonstrate decrements in neuropsychological performance beyond one week of injury. High school players demonstrated more prolonged neuropsychological effects of concussion.
Article
The performance of five newer helmets was compared with the baseline VSR-4 helmet in 10 reconstructed cases of National Football League (NFL) collisions causing concussion. The laboratory reconstructions were conducted to determine changes in concussion risk with newer football helmets. In 60 laboratory tests, translational and rotational head accelerations were measured in the striking and struck players represented by Hybrid III dummies. Six-axis upper neck loads and moments were measured in five cases with the struck player and five with the striking player. Biomechanical responses and concussion risks were evaluated for each collision to determine changes with newer helmet designs. Thirty-two out of 50 reconstructed cases showed greater than 10% reduction in severity index with newer helmets compared with the VSR-4; four cases increased. The average reduction in concussion risk with newer helmets was 10.8% (range, 6.9-16.7%) based on severity index. The reduction was 9.7% (range, 6.5-13.9%) based on translational acceleration and 18.9% (range, 10.6-23.4%) with rotational acceleration. Neck responses in the struck player showed a general reduction in moment and force with newer helmets. With newer football helmets, there was a trend toward 10 to 20% lower risks of concussion in reconstructed National Football League game collisions. However, a few designs and cases showed increased responses. The evaluation of football helmets to the proposed National Operating Committee on Standards for Athletic Equipment concussion standard should lead to more uniform reductions in concussion risk with future football helmets.
Article
PIn 1994 the National Football League (NFL) initiated a comprehensive clinical and biomechanical research study of mild traumatic brain injury (TBI), a study that is ongoing. Data on mild TBIs sustained between 1996 and 2001 were collected and submitted by NFL team physicians and athletic trainers, and these data were analyzed by the NFL's Committee on Mild Traumatic Brain Injury. At the same time, analysis of game videos was performed for on-field mild TBIs to quantify the biomechanics involved and to develop means to improve the understanding of these injuries so that manufacturers could systematically improve and update their head protective equipment. The findings and analysis of the Committee have been presented in a series of articles in Neurosurgery.
Article
We present the second reported case of autopsy-confirmed chronic traumatic encephalopathy in a retired professional football player, with neuropathological features that differ from those of the first reported case. These differing pathological features underscore the need for further empirical elucidation of the pathoetiology and pathological cascades of long-term neurodegenerative sequelae of professional football. A psychological autopsy was performed with the next-of-kin and wife. Medical and hospital records were reviewed. A complete autopsy was accompanied by a comprehensive forensic neuropathological examination. Restriction fragment length polymorphism analysis was performed to determine apolipoprotein-E genotype. Pertinent premortem history included a 14-year span of play in organized football starting from the age of 18 years. The subject was diagnosed with severe major depressive disorder without psychotic features after retirement, attempted suicide multiple times and finally committed suicide 12 years after retirement by ingestion of ethylene glycol. Autopsy revealed cardiomegaly, mild to moderate coronary artery disease, and evidence of acute ethylene glycol overdose. The brain showed no atrophy, a cavum septi pellucidi was present, and the substantia nigra showed mild pallor. The hippocampus and cerebellum were not atrophic. Amyloid plaques, cerebral amyloid angiopathy, and Lewy bodies were completely absent. Sparse to frequent tau-positive neurofibrillary tangles and neuropil threads were present in all regions of the brain. Tufted and thorn astrocytes, as well as astrocytic plaques, were absent. The apolipoprotein-E genotype was E3/E4. Our first and second cases both had long careers without multiple recorded concussions. Both manifested Major Depressive Disorder after retirement. Amyloid plaques were present in the first case and completely absent in the second case. Both cases exhibited neurofibrillary tangles, neuropil threads, and coronary atherosclerotic disease. Apolipoprotein-E4 genotypes were different. Reasons for the contrasting features in these two cases are not clear. Further studies are needed to identify and define the neuropathological cascades of chronic traumatic encephalopathy in football players, which may form the basis for prophylaxis and therapeutics.
Article
To assess the prevalence of depressive symptoms and difficulty with pain in retired professional football players, difficulties with the transition from active athletic competition to retirement, perceptions of barriers to receiving assistance for those difficulties, and recommended programs to provide such assistance. Survey sent to 3377 retired members of the National Football League Players Association (NFLPA), with usable responses received from 1617 members (functional response rate, 48.6%). Respondents were categorized as experiencing no to mild depression (N=1366; 84.5%) or moderate to severe depression (N=237; 14.7%). Respondents were also categorized according to whether they reported difficulty with pain as not or somewhat common (N=837; 51.8%) versus quite or very common (N=769; 47.6%). Respondents most frequently reported trouble sleeping, financial difficulties, marital or relationship problems, and problems with fitness, exercise, and aging, all of which were strongly correlated with the presence of moderate to severe depression and with quite or very common difficulty with pain. The same difficulties were even more commonly experienced by respondents who reported both moderate to severe depression and quite or very common difficulty with pain, compared with those who reported low scores in both domains. Retired professional football players experience levels of depressive symptoms similar to those of the general population, but the impact of these symptoms is compounded by high levels of difficulty with pain. The combination of depression and pain is strongly predictive of significant difficulties with sleep, social relationships, financial difficulties, and problems with exercise and fitness. A hypothesis explaining this association is that significant musculoskeletal disability and chronic pain interferes with physical activity and fitness during retirement and increases the risk of depression.
Article
The purpose of our study was to investigate the association between prior head injury and the likelihood of being diagnosed with clinical depression among retired professional football players with prior head injury exposure. A general health questionnaire, including information about prior injuries, the SF-36 (Short Form 36), and other markers for depression, was completed by 2552 retired professional football players with an average age of 53.8 (+/-13.4) yr and an average professional football-playing career of 6.6 (+/-3.6) yr. A second questionnaire focusing on mild cognitive impairment (MCI)-related issues was completed by a subset of 758 retired professional football players (50 yr and older). Two hundred sixty-nine (11.1%) of all respondents reported having prior or current diagnosis of clinical depression. There was an association between recurrent concussion and diagnosis of lifetime depression (chi2=71.21, df=2, P<0.005), suggesting that the prevalence increases with increasing concussion history. Compared with retired players with no history of concussion, retired players reporting three or more previous concussions (24.4%) were three times more likely to be diagnosed with depression; those with a history of one or two previous concussions (36.3%) were 1.5 times more likely to be diagnosed with depression. The analyses controlled for age, number of years since retirement, number of years played, physical component score on the SF-36, and diagnosed comorbidities such as osteoarthritis, coronary heart disease, stroke, cancer, and diabetes. Our findings suggest a possible link between recurrent sport-related concussion and increased risk of clinical depression. The findings emphasize the importance of understanding potential neurological consequences of recurrent concussion.