Sleepiness in retired male boxers: daytime sleepiness and its relationship with impulsiveness and depression symptomatology in retired professional male boxers.

BACKGROUND: Boxing exposes fighters to head impacts and potential traumatic brain injury (TBI). Though research has explored the neuropsychiatric consequences of contact sports, there is limited research into Excessive Daytime Sleepiness (EDS) and its relationship to other outcomes, such as impulsiveness and depression. Therefore, this study aimed to describe EDS in retired boxers using the Epworth Sleepiness Scale (ESS) and to examine how boxing and sleepiness relate to impulsiveness and depression symptomatology. METHODS: 86 male retired professional boxers from the Professional Fighters Brain Health Study (PFBHS) met the inclusion criteria. Adjusted multivariable models analyzed relationships between professional boxing bouts, EDS (ESS), impulsiveness (Barratt Impulsiveness Scale Version 11 (BIS-11)), and/or depression (Patient Health Questionnaire-9 (PHQ-9)). A causal mediation analysis was performed to assess whether boxing bouts and ESS scores predicted BIS-11 and PHQ-9 scores. RESULTS: Mean age was ∼51 years, fighters averaged ∼36 professional bouts, and ESS mean(SD) was 7.5(5.3). ESS scores were significantly associated with raw BIS-11 (Beta = 1.26, 95%CI = 0.77-1.75, p < 0.001) and ordinal PHQ-9 (OR = 1.20, 95%CI = 1.11-1.31, p < 0.001) scores in adjusted models, and the significant relationship between boxing bouts and BIS-11/PHQ-9 was mediated by ESS. CONCLUSIONS: EDS in retired male professional boxers may be strongly associated with other neuropsychiatric sequelae of TBI (impulsiveness and depression).Sleepiness; sleep; boxing; contact sports; impulsiveness; impulsivity; depression; Epworth sleepiness scale box.

Neurite orientation dispersion and density imaging reveals abnormal white matter and glymphatic function in active young boxers.

The neurological effects and underlying pathophysiological mechanisms of sports-related concussion (SRC) in active young boxers remain poorly understood. This study aims to investigate the impairment of white matter microstructure and assess changes in glymphatic function following SRC by utilizing neurite orientation dispersion and density imaging (NODDI) on young boxers who have sustained SRC. A total of 60 young participants were recruited, including 30 boxers diagnosed with SRC and 30 healthy individuals engaging in regular exercise. The assessment of whole-brain white matter damage was conducted using diffusion metrics, while the evaluation of glymphatic function was performed through diffusion tensor imaging (DTI) analysis along the perivascular space (DTI-ALPS) index. A two-sample t-test was utilized to examine group differences in DTI and NODDI metrics. Spearman correlation and generalized linear mixed models were employed to investigate the relationship between clinical assessments of SRC and NODDI measurements. Significant alterations were observed in DTI and NODDI metrics among young boxers with SRC. Additionally, the DTI-ALPS index in the SRC group exhibited a significantly higher value than that of the control group (left side: 1.58 vs. 1.48, PFDR = 0.009; right side: 1.61 vs. 1.51, PFDR = 0.02). Moreover, it was observed that the DTI-ALPS index correlated with poorer cognitive test results among boxers in this study population. Repetitive SRC in active young boxers is associated with diffuse white matter injury and glymphatic dysfunction, highlighting the detrimental impact on brain health. These findings highlight the importance of long-term monitoring of the neurological health of boxers.

Capturing Head Impacts in Boxing: A Video-Based Comparison of Three Wearable Sensors.

Wearable sensors are used to quantify head impacts in athletes, but recent work has shown that the number of events recorded may not be accurate. This study aimed to compare the number of head acceleration events recorded by three wearable sensors during boxing and assess how impact type and location affect the triggering of acceleration events. Seven boxers were equipped with an instrumented mouthguard, a skin patch, and a headgear patch. Contacts to participants' heads were identified via three video cameras over 115 sparring rounds. The resulting 5168 video-identified events were used as reference to quantify the sensitivity, specificity, and positive predictive value (PPV) of the sensors. The mouthguard, skin patch, and headgear patch recorded 695, 1579, and 1690 events, respectively, yielding sensitivities of 35%, 86%, and 78%, respectively, and specificities of 90%, 76%, and 75%, respectively. The mouthguard, skin patch, and headgear patch yielded 693, 1571, and 1681 true-positive events, respectively, leading to PPVs for head impacts over 96%. All three sensors were more likely to be triggered by punches landing near the sensor and cleanly on the head, although the mouthguard's sensitivity to impact location varied less than the patches. While the use of head impact sensors for assessing injury risks remains uncertain, this study provides valuable insights into the capabilities and limitations of these sensors in capturing video-verified head impact events.

Eye Trauma in Mixed Martial Arts and Boxing.

PURPOSE: To evaluate and compare eye and face trauma in mixed martial arts (MMA) and boxing. DESIGN: Retrospective cohort study. METHODS: Data from boxing and MMA competitions were extracted from the Nevada Athletic Commission (NAC) between 2000 and 2020. Details of competitions, contestants, outcomes, and injuries were extracted. RESULTS: In total 1539 boxing injuries (from 4313 contests) and 1442 MMA injuries (from 2704 contests) were identified. Boxing had higher eye injury rates compared to MMA ( p < 0.0001), with an odds ratio of 1.268 (95% CI, 1.114-1.444). Eye trauma represented 47.63% of boxing injuries and 25.59% of MMA injuries, with periocular lacerations being the most common eye injury in both. Orbital fractures represented 17.62% of eye injuries in MMA and 3.14% in boxing contests. However, 2%-3% were retinal in both sports, and 3.27% were glaucomatous in boxing. MMA contestants had an odds ratio of 1.823 (95% CI, 1.408-2.359) for requiring physician evaluation following an eye injury compared with boxing. MMA contestants also had a higher rate of face ( p < 0.0001) and body ( p < 0.0001) injuries. For both sports, an increased number of rounds and being the losing fighter were associated with increased odds of eye and face injury. CONCLUSION: Although boxing has a higher rate of eye injuries, MMA eye injuries are more likely to require physician evaluation. MMA contestants also have a higher rate of orbital fractures and face and body trauma. A detailed postfight examination and long-term follow-up of ocular injury in combat sports will be vital in proposing reforms to prevent eye trauma.

Traumatic brain injuries caused by knockout in Japanese amateur boxers: A questionnaire-based survey.

The aim of the present study is to conduct a trauma and disability survey in amateur boxers and show the actual conditions of injuries based on the current situations. We have obtained 663 valid responses from male and female boxers. In the questionnaire survey who was carried out on a Web questionnaire form. The questions involve that Face Sheet (gender, height, weight, athletic experience, etc.) and prepared 10 questions about trauma and impairment, 7 questions with concussion or damage on head. and, set 11 self-evaluations, which the boxers assessed their boxing skills. The subjects include amateur boxers who are all high school students (15 years old) and retired boxers. We had analyzed relation between the skills and the injuries. And, main outcome was that make a measure to setting whether or not questionnaires have been knockout (KO) as a variable, we applied a method of multiple logistic regression analysis. Moreover, as for the group who got KO in the past, we have also applied multiple regression analysis by using stepwise regression to factors affecting numbers of symptoms. The number of hits they experienced was smaller in international tournament matches, and the odds rate for KO was 0.669. And, KO experience group was compared with non-KO experience group, and the factors influencing the number of severity symptoms were examined. As a result, 2 factors were selected what "Seriousness in practice" and "Fighting spirit in games". It might be possible that the relation between the experience of being KO and self-assessment of boxing performance.

A Systematic Review and Meta-Analysis Investigating Head Trauma in Boxing.

OBJECTIVES: Although physical trauma has been reported in boxing since its inception, boxing still appeals to athletes and spectators. This systematic review and meta-analysis assess both acute and chronic neurological and neuropsychological effects that boxing has on the brain. Further assessments in terms of comparisons of the concussion ratio in boxing to other combat sports, as well as the efficiency of wearing headguards, are also performed. DATA SOURCES: This systematic review and meta-analysis used the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. The outcomes incorporated included physical chronic abnormalities of the brain, neuropsychiatric, and neurological disorders sustained in amateur or professional boxing, in addition to the safety benefits of boxing headguards. Odds ratios, descriptive statistics, and inferential statistics are also reported. MAIN RESULTS: From the 84 articles reviewed, the 35 included articles suggested that boxers have a significantly elevated risk of sustaining a concussion compared with other combat sports (risk ratio [RR]: 0.253 vs RR: 0.065, P < 0.001). From the 631 amateur and professional boxers analyzed, 147 (23.30%) had cavum septum pellucidum, whereas 125 of 411 amateur and professional boxers (30.41%) presented with some form of brain atrophy. Dementia or amnesia was observed in 46 of 71 boxers (61.79%), 36 of 70 (51.43%) had various forms and severities of cognitive disorders, and 57 of 109 (52.29%) displayed abnormal computed tomography or electroencephalogram scan results. Utilization of headguards significantly increased the risk for stoppages in amateur bouts, compared with boxers not wearing a headguard (OR: 1.75 vs 0.53, P < 0.050). CONCLUSIONS: Boxing is a hazardous sport that has the potential to have fatal and negative life-changing results. Because of the limited reliable data regarding the efficiency of boxing headguards, future research should focus on the overall significance that headguards may have for reducing head trauma.

Epidemiology of injuries in amateur boxing: A systematic review and meta-analysis.

OBJECTIVES: To synthesise competition and training injury data in amateur boxing. DESIGN: Systematic review and meta-analysis. Pooled estimates of competition injury incidence rates per 1000 athlete-exposures (IIRAE) and per 1000 min of exposure (IIRME), and training injury incidence rates per 1000 h of exposure (IIRHE) were obtained by fitting random-effects models. METHODS: MEDLINE, Embase, AMED, AUSPORT, and SPORTDiscus databases were searched from inception to 27 May 2022. Cohort studies with prospectively collected injury and exposure data from amateur boxing competition or training published in peer-reviewed journals were eligible for inclusion. RESULTS: Seventeen studies were eligible for inclusion. The competition IIRAE and IIRME summary estimates were 54.7 (95 % CI 33.8-88.4) and 6.8 (95 % CI 4.2-10.9), respectively. The training IIRHE summary estimate was 1.3 (95 % CI 0.2-7.0). The most commonly injured body regions in the competition and training settings were the head and neck (median: 72 %; range: 46 % to 100 %) and upper limb (median: 49 %; range: 40 % to 53 %), respectively. The predominant types of injury were contusions (median: 35 %; range: 5 % to 100 %) and lacerations and abrasions (median: 20 %; range: 0 % to 69 %) in the competition setting, and sprains and strains (median: 60 %; range: 50 % to 81 %) in the training setting. CONCLUSIONS: Amateur boxing athletes sustain, on average, 1 injury every 2.5 h of competition and every 772 h of training. There is a need for identifying injury mechanisms and modifiable risk factors that can be targeted by preventive measures to reduce the burden of injury in amateur boxing.

Extensor hood injuries in elite boxers: injury characteristics, surgical technique and outcomes.

We describe our experience of managing extensor hood injuries in boxers (57 fingers). The diagnosis was mostly clinical, with imaging only if the diagnosis was equivocal. The middle (61%) and index (26%) digits were most frequently injured. On exploration, 26% had no hood tear, however all required tenolysis from the adherent capsule. Of 42 hood tears, 15 were central splits between adjacent extensor tendons in the index or little fingers,15 tears were on the ulna side of the extensor tendon and 12 tears were on the radial side. A pseudobursa was encountered in 35%, capsular tears in 28% and chondral injury in one patient. Longitudinal curved metacarpophalangeal joint incisions were used, with hood repair performed in flexion using a locked running suture. Mean postoperative metacarpophalangeal joint flexion was 90°. Ninety-eight per cent returned to the same level of boxing at a mean of 8 months (range 1-24) from surgery. One finger was revised for re-rupture 6 months later. A reproducible technique for treating these injuries is described, with patients able to return to boxing with little risk of complications.Level of evidence: IV.

When disaster strikes in the ring: a 20-year study of head and neck injuries secondary to boxing.

The purpose of this study was to explore the patterns of head and neck injuries secondary to boxing. We conducted a 20-year retrospective cross-sectional study using the National Electronic Injury Submission System (NEISS). We derived the predictor variables from both patient and injury characteristics. The principal outcome variable was the probability of hospital admission from the ED. We used bivariate analysis to determine if an association existed between two variables of interest. We created a multiple logistic regression model to model the probability of admission using all significant univariate predictors. The final sample consisted of 1,919 patients. Children were most likely to injure their heads (p < 0.01). Young adults were also most likely to injure their heads (p < 0.05). Adults were most likely to injure their faces (p < 0.01). Children were most likely to incur facial contusions (p < 0.01) and internal organ injuries (p < 0.01). Young adults were most likely to suffer concussions (p < 0.01). Adults were most likely to suffer lacerations (p < 0.01). Certain age groups were more/less likely to injure a particular anatomical site and more/less likely to incur a particular type of injury. Relative to young adults, seniors had an increased odd of admission. Head injuries had an increased odds of admission relative to mouth injuries. Fractures and internal organ injuries proved to be the most dangerous injuries.

Rotational head acceleration and traumatic brain injury in combat sports: a systematic review.

BACKGROUND: Traumatic brain injury (TBI) in combat sports is relatively common, and rotational acceleration (RA) is a strong biomechanical predictor of TBI. This review summarizes RA values generated from head impacts in combat sport and puts them in the context of present evidence regarding TBI thresholds. SOURCES OF DATA: PubMed, EMBASE, Web of Science, Cochrane Library and Scopus were searched from inception to 31st December 2021. Twenty-two studies presenting RA data from head impacts across boxing, taekwondo, judo, wrestling and MMA were included. The AXIS tool was used to assess the quality of studies. AREAS OF AGREEMENT: RA was greater following direct head strikes compared to being thrown or taken down. RA from throws and takedowns was mostly below reported injury thresholds. Injury thresholds must not be used in the absence of clinical assessment when TBI is suspected. Athletes displaying signs or symptoms of TBI must be removed from play and medically evaluated immediately. AREAS OF CONTROVERSY: Methodological heterogeneity made it difficult to develop sport-specific conclusions. The role of headgear in certain striking sports remains contentious. GROWING POINTS: RA can be used to suggest and assess the effect of safety changes in combat sports. Gradual loading of training activities based on RA may be considered when planning sessions. Governing bodies must continue to work to minimize RA generated from head impacts. AREAS TIMELY FOR DEVELOPING RESEARCH: Prospective research collecting real-time RA data is required to further understanding of TBI in combat sports.

Epidemiology of professional bare-knuckle fighting injuries.

BACKGROUND: Professional bare-knuckle fighting (BKF) is a variation of boxing which held its first modern legal event in 2018 in Wyoming. Since then, the sport has expanded with state-sanctioned events held in Florida, Missouri, Mississippi, Kansas, and Alabama. The purpose of this study was to evaluate the epidemiology of injuries in bare-knuckle fighting bouts and to discern any trends which may distinguish it from traditional boxing with padded gloves. METHODS: Observational data collection for all state-sanctioned professional bare-knuckle fighting bouts was conducted sequentially over a two-year period from June of 2018 through November of 2020. Information related to fight outcome, injury diagnosis, and injury location was documented. This data was then analyzed and the incidence rates by injury type and location were calculated. RESULTS: There were 141 bouts conducted during the study period. Out of the 282 individual combatants, 105 (36.6%) sustained at least one injury during the event and 123 total injuries were recorded. In total, 98 (34.8%) lacerations were recorded; on average, 6.2 +- 4.5 sutures were required per laceration. There were 5 superficial hand lacerations and 80 facial lacerations. Seventeen (6.0%) fractures occurred, with 8 hand fractures, 6 nasal fractures, 2 orbital fractures, and 2 dental fractures. There were 8 (2.8%) periorbital hematomas sustained by fighters. Transfer to the hospital was required on 5 (1.8%) separate occasions, twice for orbital fractures and 3 times for traumatic brain injuries. In all, there were 8 (2.8%) concussions with symptoms. CONCLUSION: The most frequent injuries in BKF include lacerations and hand fractures. Concussions are relatively uncommon compared to other injuries.

Mortality from mental disorders and suicide in male professional American football and soccer players: A meta-analysis.

OBJECTIVE: To determine the risk of mortality from mental disorders and suicide in professional sports associated with repeated head impacts. METHODS: A systematic search was performed in PubMed, Web of Science, Scopus, and SPORTDiscus (since inception to June 8, 2021) to find studies comparing the incidence of mortality from mental disorders or suicide in former or active professional athletes of sports characterized by repeated head impacts vs athletes with no such exposure or the general non-athletic population. RESULTS: Seven retrospective studies of moderate-to-high quality that included data from boxers and from basketball, ice hockey, soccer, and National Football League (NFL) players, respectively (total = 27 477 athletes, 100% male) met all inclusion criteria. Former male NFL players (n = 13 217) had a lower risk of mortality from mental disorders (standard mortality rate [SMR] = 0.30; 0.12-0.77; p = 0.012) and suicide (SMR = 0.54; 0.37-0.78; p < 0.001) than the general population. This finding was also corroborated in male soccer players (n = 13,065; SMR = 0.55; 0.46-0.67; p < 0.001). Male athletes participating in sports associated with repeated head impacts (n = 18,606) had also a lower risk of all-cause, cardiovascular disease (CVD), and cancer mortality (all p < 0.01) than the general population. CONCLUSIONS: Participation of male athletes in American football or soccer at the professional level might confer a certain protective effect against mortality from mental disorders or suicide, besides its association with a lower risk of all-cause, CVD, or cancer-related mortality.

Altered Vestibular Balance Function in Combat Sport Athletes.

Combat sports pose a risk for accumulative injuries to the nervous system, yet fighters have remained an understudied population. Here, our purpose was to determine whether repetitive blows to the head have an effect on vestibular balance reflexes in combat sports athletes. We compared lower-limb muscle responses evoked with electrical vestibular stimuluation (EVS) between fighters (boxing/muay thai) and non-fighter controls. Each participant received stochastic vestibular stimulation (0-25 Hz, ±3 mA) over their mastoid processes while they stood relaxed with their head to the left or right. Surface electromyography was recorded from the medial gastrocnemius and soleus muscles bilaterally. Short and medium latency response (SLR/MLR) peaks were significantly delayed in the fighter group compared to controls. SLR and MLR peak amplitudes were also significantly lower in fighters. Fighter-estimated cumulative repetitive head impact (RHI) events demonstrated strong positive correlations with the timing of SLR and MLR peaks. Cumulative RHI events also negatively correlated with peak MLR amplitude and response gain at frequencies above 5 Hz. Our results provide evidence of a progressive vestibular impairment in combat sports athletes, potentially resulting from blows to the head accumulated in sparring practice and competitive bouts throughout their careers. Taken together, EVS-based vestibular assessments may provide a valuable clinical diagnostic tool and help better inform "return-to-play" and career-length decisions for not only combat sports athletes, but potentially other populations at risk of RHIs.

CSF and Blood Neurofilament Levels in Athletes Participating in Physical Contact Sports: A Systematic Review.

OBJECTIVE: To evaluate whether participating in physical contact sports is associated with a release of neurofilaments and whether such release is related to future clinical neurologic and/or psychiatric impairment. METHODS: We performed a systematic review of the PubMed, MEDLINE, and Cochrane Library databases using a combination of the search terms neurofilament(s)/intermediate filament and sport(s)/athletes. Original studies, written in English, reporting on neurofilaments in CSF and/or serum/plasma of contact sport athletes were included. This review was conducted following the Preferred Reporting Items for Systematic Review and Analyses guidelines. RESULTS: Eighteen studies in 8 different contact sports (i.e., boxing, American football, ice hockey, soccer, mixed martial arts, lacrosse, rugby, and wrestling) matched our criteria. Elevated light chain neurofilament (NfL) levels were described in 13/18 cohorts. Most compelling evidence was present in boxing and American football, where exposure-related increases were appreciable at the intraindividual level (up to 4.1- and 2.0-fold, respectively) in well-defined groups. Differences in exposure severity (including previous cumulative effects), sampling/measurement time points (with regard to expected peak values), and definitions of the baseline setting are considered as main contributors to the variability in findings. No studies were encountered that have investigated the relationship with the targeted clinical end points; therefore no NfL cutoffs exist that are associated with a poor outcome. CONCLUSION: NfL release can be seen, as a potential marker of neuronal brain damage, in participants of physical contact sports, particularly boxing and American football. The exact significance regarding the risk for future clinical impairment remains to be elucidated.

The association of concussion history and symptom presentation in combat sport athletes.

OBJECTIVE: The purpose of this study was to describe the concussion-related symptoms reported among combat sport athletes with and without a history of concussion, and a history of neck injury. DESIGN: Cross-sectional survey. SETTING: Data were collected using an online survey instrument. PARTICIPANTS: Three hundred and nine adult combat sport athletes. MAIN OUTCOME MEASURES: Self-reported 12-month concussion history and neck injury history and a 22-item symptom checklist. RESULTS: A history of concussion was reported by 19.1% of athletes, a history of neck injury was reported by 23.0%, and 13.6% reported both injuries. Neck pain was the most frequently reported symptom. Athletes with a history of injury had significantly greater proportions of 'high' total symptoms and symptom severity scores compared with athletes with no history of injury. Athletes with a history of concussion had 2.35 times higher odds of reporting 'high' total symptoms and symptoms severity scores. CONCLUSION: Athletes with a history of concussion or neck injury have greater odds of presenting with higher symptom scores. The presence of high total symptom scores and high symptom severity scores may indicate a need for further investigation into domains commonly associated with concussion.

Surgical Management of Symptomatic Boxing-Induced Spinal Cerebrospinal Fluid Leak After Failed Epidural Blood Patch.

BACKGROUND: Spontaneous spinal cerebrospinal fluid (CSF) leak is an increasingly recognized condition responsible for spontaneous intracranial hypotension. A host of connective tissue disorders and mechanical factors may precipitate the condition. Conservative treatment has limited efficacy, and many patients with persistent symptoms ultimately require epidural blood patch (EBP). However, about 23%-44% of patients experience recurrence of symptoms after EBP. Unidentified or multiple sites of CSF leaks are thought to be responsible for the failure of EBP. Using our previously published technique, we treated a patient who developed a large spontaneous CSF leak in her cervicothoracic spine after a boxing class, offering further evidence of the utility of the technique for select patients. CASE DESCRIPTION: A 28-year-old woman was referred to our center with recurrent, severe headaches and associated nausea and vomiting. She underwent EBP 3 times with no resolution of her symptoms. A right-side partial C7-T1 hemilaminotomy was performed to identify a large meningocele filled with CSF. After dissection, dural sealant was applied using an angled needle with a syringe to buttress the meningocele to allow for normalization of the hydrostatic pressure. At 5-month follow-up, her symptoms have resolved with no headaches and paresthesias in upper limbs. CONCLUSIONS: Commonplace events, such as a boxing/sparring class, may precipitate a spontaneous spinal CSF leak. Our minimally invasive surgical approach can be safely used in patients with spontaneous intracranial hypotension with recurrent symptoms, no identified leak site, and prior failed attempts of EBP.

Neuroimaging in the Diagnosis of Chronic Traumatic Encephalopathy: A Systematic Review.

OBJECTIVE: Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repeated subconcussive and concussive head injury. Clinical features include cognitive, behavioral, mood, and motor impairments. Definitive diagnosis is only possible at postmortem. Here, the utility of neuroimaging in the diagnosis of CTE is evaluated by systematically reviewing recent evidence for changes in neuroimaging biomarkers in suspected cases of CTE compared with controls. DATA SOURCES: Providing an update on a previous systematic review of articles published until December 2014, we searched for articles published between December 2014 and July 2016. We searched PubMed for studies assessing neuroimaging changes in symptomatic suspected cases of CTE with a history of repeated subconcussive or concussive head injury or participation in contact sports involving direct impact to the head. Exclusion criteria were case studies, review articles, and articles focusing on repetitive head trauma from military service, head banging, epilepsy, physical abuse, or animal models. MAIN RESULTS: Seven articles met the review criteria, almost all of which studied professional athletes. The range of modalities were categorized into structural magnetic resonance imaging (MRI), diffusion MRI, and radionuclide studies. Biomarkers which differed significantly between suspected CTE and controls were Evans index (P = 0.05), cavum septum pellucidum (CSP) rate (P < 0.0006), length (P < 0.03) and ratio of CSP length to septum length (P < 0.03), regional differences in axial diffusivity (P < 0.05) and free/intracellular water fractions (P < 0.005), single-photon emission computed tomography perfusion abnormalities (P < 0.01), positron emission tomography (PET) signals from tau-binding, glucose-binding, and GABA receptor-binding radionuclides (P < 0.0001, P < 0.005, and P < 0.005, respectively). Important limitations include low specificity in identification of suspected cases of CTE across studies, the need for postmortem validation, and a lack of generalizability to nonprofessional athletes. CONCLUSIONS: The most promising biomarker is tau-binding radionuclide PET signal because it is most specific to the underlying neuropathology and differentiated CTE from both controls and patients with Alzheimer disease (P < 0.0001). Multimodal imaging will improve specificity further. Future research should minimize variability in identification of suspected cases of CTE using published clinical criteria.

Measuring Blunt Force Head Impacts in Athletes.

INTRODUCTION: Although concussion continues to be a major source of acute and chronic injuries, concussion injury mechanisms and risk functions are ill-defined. This lack of definition has hindered efforts to develop standardized concussion monitoring, safety testing, and protective countermeasures. To overcome this knowledge gap, we have developed, tested, and deployed a head impact monitoring mouthguard (IMM) system. MATERIALS AND METHODS: The IMM system was first calibrated in 731 laboratory tests. Versus reference, Laboratory IMM data fit a linear model, with results close to the ideal linear model of form y = x + 0, R2 = 1. Next, during on-field play involving n = 54 amateur American athletes in football and boxing, there were tens of thousands of events collected by the IMM. A total of 890 true-positive head impacts were confirmed using a combination of signal processing and National Institute of Neurological Disorders and Stroke/National Institutes of Health Common Data Elements methods. RESULTS: The median and 99th percentile of peak scalar linear acceleration and peak angular acceleration were 20 and 50 g and 1,700 and 4,600 rad/s2, respectively. No athletes were diagnosed with concussion. CONCLUSIONS: While these data are useful for preliminary human tolerance limits, a larger population must be used to quantify real-world dose response as a function of impact magnitude, direction, location, and accumulation. This work is ongoing.

Understanding concussion knowledge and behavior among mixed martial arts, boxing, kickboxing, and Muay Thai athletes and coaches.

Objectives: In combat sports, strikes to the head are not just incidental but a deliberate and clear determinant of success. Concussion is a complex injury that is poorly understood and inappropriate practices are often observed among athletes and coaches. The purpose of this study was to investigate concussion knowledge and behavior as well as address recommendations for combat sports athletes and coaches. Methods: 70 athletes and 35 coaches from combat sports disciplines completed an online-validated survey and a personal questionnaire about concussion knowledge, training experience, and knowledge translation. Athletes were divided into subgroups for analysis according to sex (male n = 55, female n = 15), skill level (amateur n = 52, professional n = 18), and weight classes (<66.2 kg: n = 25, 66.6 to 77.5 kg: n = 30, and >78 kg: n = 15). Results: The likely absence of health-care professionals during training was confirmed by 68.5% of coaches, and athletes declared that self-diagnosis (79%) and coaches' diagnosis (43.3%) were the most used method of suspected concussion assessment. Merely 5.7% of coaches properly recognized the level of traumatic brain injury a concussion represents, 68.8% were unfamiliar with any sideline assessment tools, and only 14.3% often seek out concussion knowledge. Athletes who were aware of the level of brain injury a concussion represents performed fewer sparring sessions per week (mild: 1.27 ± 1.1; severe: 3.17 ± 2.81; p = .05, d = .89) and had a greater likelihood of reporting concussive episodes. Most professional (55.5%), female (54.5%), and under 66.2 kg (50%) athletes returned to full practice within 1 week following a concussion diagnosis. Conclusions: Relevant key gaps of knowledge and behavior were verified in combat sports athletes and coaches. The awareness of basic concepts may improve injury reporting and safer behavior in athletes. Knowledge translation strategies with accessible language are recommended for coaches, in particular on how to identify acute symptoms and perform basic assessment.