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Background: A 2021 National Institute for Neurological Disorders and Stroke (NINDS) consensus panel proposed a set of clinical diagnostic criteria for traumatic encephalopathy syndrome (TES) and determined provisional levels of certainty for chronic traumatic encephalopathy (CTE) pathology based on neuropathological evidence. The panel suggested the criteria needed to be validated by clinical studies of living populations exposed to repetitive head impacts (RHIs). Hypothesis: As the consensus criteria were developed solely from neuropathologically diagnosed cases of CTE, we hypothesized that they may not be readily applicable to the clinical impressions developed from the histories and examination findings of living patients whose neuropathology was unknown. Study Design: We applied the consensus criteria to 4 groups of living retired contact sports athletes collected from previously published articles in the medical literature. Level of Evidence: Level 4. Methods: Clinical evidence from 4 groups of living retired athletes (boxers and American football players) with extensive RHI exposure was available. We used the NINDS consensus criteria to determine for each athlete whether or not they met the criteria for TES. For those who met the criteria, we determined their provisional level of certainty for CTE pathology. Results: Among all 80 subjects, the prevalence of TES was 21.3% (17 of 80), the prevalence of possible CTE was 12.5% (10 of 80), and the prevalence of probable CTE was 2.5% (2 of 80). Among the 45 retired football players, the prevalence of TES was 24.4% (11 of 45) and the prevalence of possible CTE was 17.7% (8 of 45). None of the retired football players met the criteria for probable CTE. Among the 35 total retired boxers (from all 3 groups), the prevalence of TES was 17.1% (6 of 35), the prevalence of possible CTE was 5.7% (2 of 35), and the prevalence of probable CTE was 5.7% (2 of 35). Conclusion: Applying the NINDS consensus criteria to this historical cohort of living retired athletes with extensive RHI exposure resulted in a relatively low prevalence of TES and possible/probable certainties of CTE pathology, which might suggest limitations on the sensitivity of the NINDS criteria. Clinical Relevance: Physicians are often asked by retired contact sports athletes and their families to determine if their clinical picture is related to TES and/or CTE. Physicians may turn to the NINDS consensus criteria for guidance in making such determinations. The data presented here may assist physicians in evaluating the reliability and validity of using the consensus criteria in living subjects. [ABSTRACT FROM AUTHOR]

The long-term effects of repetitive head trauma on the brain have often been studied in boxers and American football players. The medical literature on this topic was reviewed in order to compare the findings related to boxing with those related to football. The evidence gathered from this review indicates that there are significant differences between the clinical and neuropathological descriptions of the chronic brain damage reported in retired boxers compared to those reported in retired football players. Differing biomechanics of head impacts in the two sports may help explain the different clinical and neuropathological consequences of participation in boxing versus football. [ABSTRACT FROM AUTHOR]

Background: Structural brain changes, potentially resulting from repetitive brain trauma (RBT), have been correlated with neurocognitive decline and increased symptom reporting in retired athletes.Hypothesis: In a cohort of retired National Football League (NFL) players, the relationships between 3 neuroimaging parameters, neuropsychological testing, and symptom scores will be significantly correlated.Study Design: Cross-sectional study.Level Of Evidence: Level 3.Methods: Comprehensive magnetic resonance imaging was performed in 45 retired NFL players. Three neuroanatomical parameters were assessed by board-certified radiologists blinded to the purpose of the study: (1) the absence or presence of small or large cavum septum pellucidum, (2) a global mean score of fractional anisotropy (FA), and (3) the presence or absence of microhemorrhages. The subjects underwent a battery of 9 paper-and-pencil neuropsychological tests, a computerized neurocognitive test, and multiple symptom and depression scales. The associations among the neuroimaging results with these outcome measures were assessed utilizing Pearson, Spearman rank, and point-biserial correlations.Results: The 45 subjects (mean age, 46.7 ± 9.1 years) reported a mean 6.9 (±6.2) concussions and 13.0 (±7.9) "dings" in the NFL. Ten (22%) did not have a cavum septum pellucidum, while 32 (71%) had a small and 3 (7%) had a large one. Four (9%) had microhemorrhages. Global FA mean was 0.459 (±0.035). The majority (50.8%) of correlations among the neuroimaging parameters and neurocognitive/symptom scores fell below the threshold of "small" effect size ( r < 0.10). The remaining (49.2%) correlations were between "small" and "medium" effect sizes (0.1 < r < 0.3). However, all correlations were statistically nonsignificant.Conclusion: There were minimal and statistically nonsignificant correlations among the neuroimaging, neurocognitive, and symptom scores examined in this cohort of NFL retirees.Clinical Relevance: Associating the severity of structural brain changes to neurocognitive performance and symptom burden after RBT is complex may involve other moderating variables or biomarkers, and demands further study. [ABSTRACT FROM AUTHOR]

The article focuses on a study that determine whether there was clinical evidence of chronic brain damage related to a career in the National Football League (NFL) players. Medical examination was consucted on 45 retired NFL players and their hostories focused on neurological and depression symptoms. Study found that number of football-related concussions was associated with isolated abnormalities on the clinical neurological examination.

Background: 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).Hypothesis: More players were held out 7+ days in the 2002-2007 period without significant difference in concussion signs and symptoms.Study Design: Cohort.Methods: From 1996 through 2007, National Football League team physicians reported concussion signs and symptoms, medical action taken, and follow-up management.Results: 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%).Conclusions: 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. [ABSTRACT FROM AUTHOR]

Background: Repeat concussion is an important issue in the National Football League (NFL). An initial description of repeat injuries was published for 6 years (1996-2001).Hypothesis: The characteristics and frequency of repeat concussion in the NFL have not changed in the subsequent 6 years (2002-2007).Study Design: Case control.Methods: From 1996 to 2007, concussions were reported using a standardized form documenting signs and symptoms, loss of consciousness and medical action taken. Data on repeat concussions were analyzed for the 12 years and compared between the 2 periods.Results: In 2002-2007, 152 players had repeat concussions (vs 160 in 1996-2001); 44 had 3+ head injuries (vs 52). The positions most often associated with repeat concussion in 2002-2007 were the defensive secondary, kick unit, running back, and linebacker. The odds for repeat concussion were elevated for wide receivers, tight ends, and linebackers but lower than in the earlier period. During 2002-2007, over half of players with repeat concussion were removed from play, and fewer immediately returned (vs 1996-2001). The average duration between concussions was 1.25 years for 2002-2007 and 1.65 years for the 12-year period. Over 12 years, 7.6% of all repeat concussions occurred within 2 weeks of the prior concussion.Conclusions: The defensive secondary, kick unit, running back, and linebacker have the highest incidence of repeat concussion. During 2002-2007, more than half of players with repeat concussion were removed from play, and only a fraction immediately returned. Although concussion was managed more conservatively by team physicians in the recent 6 years, repeat concussions occurred at similar rates during both periods. [ABSTRACT FROM AUTHOR]

Background: 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.Hypothesis: The increased attention to concussions may have resulted in team physicians being more conservative in treating players in recent years.Study Design: 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.Methods: 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.Results: 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.Conclusion: 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.Clinical Relevance: 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. [ABSTRACT FROM AUTHOR]

The authors' studies have yielded a great deal of data regarding the biomechanics of head injury and the clinical picture of mild traumatic brain injury (MTBI) in the National Football League (NFL). The research has demonstrated the link between the effects of biomechanical forces on the brain and the clinical symptomatology of the concussed players. New insights into the mechanisms of injury are leading to new ways of protecting football players from the effects of MTBI. The clinical data validate the effectiveness of the current NFL physician approach to the evaluation and treatment of the player who sustains MTBI. There are still many more questions to answer and much more knowledge to be gained from continuing research in this area.

Objective: 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., Methods: 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., Results: 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., Conclusion: 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.

Objective: Acute recovery from concussion (mild traumatic brain injury) is assessed in samples of NFL and high school athletes evaluated within days of injury., Methods: 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)., Results: 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., Conclusion: 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.