Longitudinal auditory pathophysiology following mild blast-induced trauma.

Blast-induced hearing difficulties affect thousands of veterans and civilians. The long-term impact of even a mild blast exposure on the central auditory system is hypothesized to contribute to lasting behavioral complaints associated with mild blast traumatic brain injury (bTBI). Although recovery from mild blast has been studied separately over brief or long time windows, few, if any, studies have investigated recovery longitudinally over short-term and longer-term (months) time windows. Specifically, many peripheral measures of auditory function either recover or exhibit subclinical deficits, masking deficits in processing complex, real-world stimuli that may recover differently. Thus, examining the acute time course and pattern of neurophysiological impairment using appropriate stimuli is critical to better understanding and intervening in bTBI-induced auditory system impairments. Here, we compared auditory brainstem response, middle-latency auditory-evoked potentials, and envelope following responses. Stimuli were clicks, tone pips, amplitude-modulated tones in quiet and in noise, and speech-like stimuli (iterated rippled noise pitch contours) in adult male rats subjected to mild blast and sham exposure over the course of 2 mo. We found that blast animals demonstrated drastic threshold increases and auditory transmission deficits immediately after blast exposure, followed by substantial recovery during the window of 7-14 days postblast, although with some deficits remaining even after 2 mo. Challenging conditions and speech-like stimuli can better elucidate mild bTBI-induced auditory deficit during this period. Our results suggest multiphasic recovery and therefore potentially different time windows for treatment, and deficits can be best observed using a small battery of sound stimuli.NEW & NOTEWORTHY Few studies on blast-induced hearing deficits go beyond simple sounds and sparsely track postexposure. Therefore, the recovery arc for potential therapies and real-world listening is poorly understood. Evidence suggested multiple recovery phases over 2 mo postexposure. Hearing thresholds largely recovered within 14 days and partially explained recovery. However, midlatency responses, responses to amplitude modulation in noise, and speech-like pitch sweeps exhibited extended changes, implying persistent central auditory deficits and the importance of subclinical threshold shifts.

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.

Dangers of Mixed Martial Arts in the Development of Chronic Traumatic Encephalopathy.

Chronic traumatic encephalopathy (CTE) was first discovered in professional boxers after they exhibited memory impairments, mood and behavioral changes after years of boxing. However, there is now a growing acceptance that CTE can develop in athletes of other sports due to the repetitive head trauma they receive. We present a case of a middle-aged male who presented with worsening memory, poor concentration, and behavioral changes for a year. On further cognitive testing, it was revealed that he had difficulties with short-term memory and processing speed as well as difficulties in organizing and multitasking. He had been practicing mixed martial arts (MMA) for 10 years, and later was an instructor of the sport. Through a detailed examination of his history, it was discovered that he sustained recurrent minor head concussions due to his line of work. To date, there has been limited large-scale research on head trauma in MMA. There is thus an urgent need for more studies in this area as CTE can be a chronic and debilitating illness with incapacitating neuropsychiatric sequelae. This case highlights the importance of public awareness of the risks of MMA and the dangers it poses to the brain, especially with more young people being attracted to this sport.

Concussion reporting and perceived knowledge of professional fighters.

Objective: For concussions to be effectively managed in sports, they need to be correctly identified and reported. The extent to which professional athletes correctly recognize concussions, and their willingness to report symptoms, is not yet well understood. Given the risk of head injuries leading to concussions across combat sports, insight into professional fighters' knowledge and reporting of concussive symptoms is essential to improve concussion management. Methods: To investigate understanding and reporting patterns of concussions sustained while training or competing, 257 fighters completed a self-report questionnaire assessing self-perception of concussion knowledge, trust of ringside medical providers, and reported number of previous head injuries. Fighting history, including number of knockouts, was obtained from self-report (amateur) and published (professional) records. Results: Significant gaps in fighters' perceived knowledge of concussion symptoms and long-term effects of multiple concussions emerged. Approximately 40% of fighters reported returning to training or competition the same day a head injury was sustained, while 21% of fighters endorsed concealing symptoms of head injury from medical providers and coaches. Conclusions: Confusion surrounding terms used to describe head injuries amongst fighters (e.g., concussions, knockouts), coupled with limited understanding of concussive symptoms and a desire to return to competition, likely contributes to significant underreporting of symptoms.

The King-Devick test in mixed martial arts: the immediate consequences of knock-outs, technical knock-outs, and chokes on brain functions.

The aim of this prospective cohort study was to determine the effect of an 'event,' defined as a knock-out (KO), technical knock-out (TKO), choke, or submission, on King-Devick (K-D) test times in mixed martial arts (MMA) athletes. MMA athletes (28.3 ± 6.6 years, n = 92) underwent K-D testing prior to and following a workout or match. Comparison of baseline and post-workout/match K-D times to assess any significant change. K-D tests worsened (longer) in a majority of athletes following an 'event' (N = 21) (49.6 ± 7.8 s vs 46.6 ± 7.8 s, p = 0.0156, Wilcoxon signed-rank test). K-D tests improved (shorter) following a standard workout or match in which no 'event' occurred in a majority of cases (n = 69) (44.2 ± 7.2 s vs 49.2 ± 10.9 s, p = <0.0001, Wilcoxon signed-rank test). Longer duration (worsening) of post-match K-D tests occurred in most athletes sustaining an 'event'; K-D tests shortened (improved) in a majority of athletes not sustaining an 'event'. Our study suggests MMA athletes suffering an 'event' may have sustained a brain injury similar to a concussion.

Systematic review of injuries in mixed martial arts.

OBJECTIVES: To assess injury rates in all mixed martial arts (MMA) studies. METHODS: Six online databases were searched until November 2017 including MEDLINE, EMBASE, CINAHL, Web of Science, PubMed, Google/Google Scholar and conference proceedings. All included studies were entered in Pub Med Single Citation Matcher and all citation chains followed. Abstracts and titles were assessed for relevance, data independently abstracted and risk of bias for all competition studies evaluated independently by two reviewers. RESULTS: There are data for 5,374 male and 108 female MMA fighters. For 2407 males the weighted average injury rate/1000Athletic Encounters (AE) was 246.4 and for one study of 108 females 101.9. One study provided data by professional status: professionals 135.5/1000AE and amateurs 71.0/1000AE. Reasons for stopping matches were knockout/technical knockout 173.9/1000AE for males and 175.9/1000AE for females, submission 228.6/1000AE, and referee's decision 98.2/1000AE. Losers can experience large amounts of trauma especially head trauma as matches terminate. Two studies of competitions provided personally conducted ringside assessments and both pre- and post-match examination results. The other studies reported retrospective assessments of fight records or videos or videos and scorecards. There are no studies of training injuries of professionals or injuries of amateurs or long-term follow-up of musculoskeletal injuries or neurological damage. Studies are limited to the US and Canada. There are no systematic reviews of newspaper or media accounts of fights to assess rates and numbers of injuries or mortality. The few published surveys and case reports markedly understate the worldwide situation. CONCLUSIONS: There are high rates of trauma in MMA. The authorities who regulate MMA and referees and physicians who monitor MMA fighters have an inadequate database to guide their work. Researchers need to adopt the same set of complete definitions of all possible injuries and measure the high and early rate of neurological damage.

Safety of Active Rehabilitation for Persistent Symptoms After Pediatric Sport-Related Concussion: A Randomized Controlled Trial.

OBJECTIVES: To examine the safety and tolerability of an active rehabilitation program for adolescents who are slow to recover from a sport-related concussion, and secondarily to estimate the treatment effect for this intervention. DESIGN: Single-site, parallel, open-label, randomized controlled trial comparing treatment as usual (TAU) to TAU plus active rehabilitation. SETTING: Outpatient concussion clinic. PARTICIPANTS: Adolescents (N=19) aged 12 to 18 years with postconcussion symptoms lasting ≥1 month after a sports-related concussion. INTERVENTIONS: TAU consisted of symptom management and return-to-play advice, return-to-school facilitation, and physiatry consultation. The active rehabilitation program involved in-clinic subsymptom threshold aerobic training, coordination exercises, and visualization and imagery techniques with a physiotherapist (mean, 3.4 sessions) as well as a home exercise program, over 6 weeks. MAIN OUTCOME MEASURES: A blinded assessor systematically monitored for predetermined adverse events in weekly telephone calls over the 6-week intervention period. The treating physiotherapist also recorded in-clinic symptom exacerbations during aerobic training. The Post-Concussion Symptom Scale was the primary efficacy outcome. RESULTS: Nineteen participants were randomized, and none dropped out of the study. Of the 12 adverse events detected (6 in each group), 10 were symptom exacerbations from 1 weekly telephone assessment to the next, and 2 were emergency department visits. Four adverse events were referred to an external safety committee and deemed unrelated to the study procedures. In-clinic symptom exacerbations occurred in 30% (9/30) of aerobic training sessions, but resolved within 24 hours in all instances. In linear mixed modeling, active rehabilitation was associated with a greater reduction on the Post-Concussion Symptom Scale than TAU only. CONCLUSIONS: The results support the safety, tolerability, and potential efficacy of active rehabilitation for adolescents with persistent postconcussion symptoms.

GABA alterations in pediatric sport concussion.

OBJECTIVE: To evaluate whether frontal-lobe magnetic resonance spectroscopy measures of γ-aminobutyric acid (GABA) would be altered in a sample of adolescents scanned after sport concussion because mild traumatic brain injury is often associated with working memory problems. METHODS: Eleven adolescents (age 14-17 years) who had sustained a first-time sport concussion were studied with MRI/magnetic resonance spectroscopy within 23 to 44 days after injury (mean 30.4 ± 6.1 days). Age- and sex-matched healthy controls, being seen for sports-related injuries not involving the head and with no history of concussion, were also examined. GABA/creatine + phosphocreatine (Cre) was measured in left-sided frontal lobe and central posterior cingulate regions. The frontal voxel was positioned to overlap with patient-specific activation on a 1-back working memory task. RESULTS: Increased GABA/Cre was shown in the frontal lobe for the concussed group. A decreased relationship was observed in the parietal region. High correlations between GABA/Cre and task activation were observed for the control group in the frontal lobe, a relationship not shown in the concussed participants. CONCLUSIONS: GABA/Cre appears increased in a region colocalized with working memory task activation after sport concussion. Further work extending these results in larger samples and at time points across the injury episode will aid in refining the clinical significance of these observations.

Injuries in taekwando: systematic review.

OBJECTIVES: Assess rates/1000athletic encounters(AE) in Taekwondo of injuries/age/gender/type/location. METHODS: Searches in 17 electronic, 7 grey-literature databases. Two researchers independently assessed Abstracts/titles and abstracted data. Risk-of-bias assessed with Newcastle-Ottawa scale. Rates/1000AE computed, weighted by study sizes. RESULTS: Eighteen studies included 3 Olympic, 4 world, 1 European, 13 national, 10 provincial and one national school competition. Seventeen studies provided an injury definition and recorded injuries on forms. Rates are average rate/1000AE, weighted by study size. For ten studies which provided rates by gender, rate for males(n = 9,286) was 58/1000AE and females(n = 3,720) 52.7/1000AE. For six studies which provided data on injuries/1000minutes/exposure by gender rate for males(n = 6,885) was 10.7/1000minutes/exposure and for females(n = 2,539) 10.4. For two studies which provided data by age and gender, rate for males 11-13 years(n = 949) was 29.6, 14-17(n = 512) 53.1 and ≥18(n = 711) 40.7, and for females 11-13 years(n = 472) 30.5, 14-17(n = 338) 72 and ≥18(n = 240) 37.5. For eight studies which provided injury location rates by gender rate for all ages for males(n = 5,856) for head/neck injuries was 13.3, torso 4.2, upper-extremity 9.4 and lower-extremity 21.7 and females(n = 2,126) for head/neck injuries was 14.2, torso 3.1, upper-extremity 7.3 and lower-extremity 26.6. For nine studies which provided injury type rates by gender, rate for all ages for males(n = 7,509) for abrasions/contusions/lacerations was 37.5, for sprains/strains 10.3 and fractures 5.9, and for females(n = 2,852) for abrasions/contusions/lacerations 27.9, for sprains/strains 8.7 and fractures 3.8. For concussions for eight studies for males(n = 9,078) rate was 13.3 and females(n = 3628) 11.4. The majority of injuries occurred to the lower extremities, and in defence (61%). CONCLUSIONS: There are published data on 20,210 Taekweondo competitors. Only 8/18 studies reported prior injuries. Longitudinal studies are needed of injuries, ascertainment of causes, identify participants with higher rates, measure the results of preventive measures, rule change to exclude head kicks, and encourage non-contact Taekwondo especially for participants with high injury rates.

No Effect of Anodal Transcranial Direct Current Stimulation on Gamma-Aminobutyric Acid Levels in Patients with Recurrent Mild Traumatic Brain Injury.

In patients in the chronic phase after recurrent mild traumatic brain injury (mTBI), alterations in gamma-aminobutyric acid (GABA) concentration and receptor activity have been reported, possibly mediating subtle but persistent cognitive deficits and increased rate of dementia in older age. We evaluated whether anodal transcranial direct current stimulation (atDCS) over the primary motor cortex reduces GABA concentration and GABAB receptor activity in patients with recurrent mTBI. Seventeen patients (mean age 25, two women) in the chronic phase after recurrent mTBI and 22 healthy control subjects (mean age 26, two women) were included. All participants received comprehensive cognitive testing and detailed questionnaires on post-concussive symptoms at baseline. Subsequently, they participated in four experimental sessions, consisting of either magnetic resonance spectroscopy (MRS)/atDCS/MRS, transcranial magnetic stimulation (TMS)/atDCS/TMS, MRS/sham/MRS, or TMS/sham/TMS to determine GABA concentration (from MRS) and GABAB receptor activity (from TMS) after atDCS and after sham stimulation. Patients with mTBI scored significantly lower on verbal fluency tasks compared with healthy control subjects. GABA concentration at baseline was associated with the number of mTBI, although no group differences in GABA concentration and GABAB receptor activity were found. Moreover, no effects of atDCS on GABA concentration and receptor activity were seen in patients with mTBI or healthy control subjects. GABA concentration may increase with the number of mTBI, but atDCS did not modulate GABA concentration and receptor activity, as has been reported previously. Specifics of experimental design and analysis, but also characteristics of the respective samples, may account for these differential findings, and should be addressed in future larger studies.

Multidisciplinary Management of Pediatric Sports-Related Concussion.

OBJECTIVES: To summarize the clinical characteristics and outcomes of pediatric sports-related concussion (SRC) patients who were evaluated and managed at a multidisciplinary pediatric concussion program and examine the healthcare resources and personnel required to meet the needs of this patient population. METHODS: We conducted a retrospective review of all pediatric SRC patients referred to the Pan Am Concussion Program from September 1st, 2013 to May 25th, 2015. Initial assessments and diagnoses were carried out by a single neurosurgeon. Return-to-Play decision-making was carried out by the multidisciplinary team. RESULTS: 604 patients, including 423 pediatric SRC patients were evaluated at the Pan Am Concussion Program during the study period. The mean age of study patients was 14.30 years (SD: 2.32, range 7-19 years); 252 (59.57%) were males. Hockey (182; 43.03%) and soccer (60; 14.18%) were the most commonly played sports at the time of injury. Overall, 294 (69.50%) of SRC patients met the clinical criteria for concussion recovery, while 75 (17.73%) were lost to follow-up, and 53 (12.53%) remained in active treatment at the end of the study period. The median duration of symptoms among the 261 acute SRC patients with complete follow-up was 23 days (IQR: 15, 36). Overall, 25.30% of pediatric SRC patients underwent at least one diagnostic imaging test and 32.62% received referral to another member of our multidisciplinary clinical team. CONCLUSION: Comprehensive care of pediatric SRC patients requires access to appropriate diagnostic resources and the multidisciplinary collaboration of experts with national and provincially-recognized training in TBI.

Youth Participation and Injury Risk in Martial Arts.

The martial arts can provide children and adolescents with vigorous levels of physical exercise that can improve overall physical fitness. The various types of martial arts encompass noncontact basic forms and techniques that may have a lower relative risk of injury. Contact-based sparring with competitive training and bouts have a higher risk of injury. This clinical report describes important techniques and movement patterns in several types of martial arts and reviews frequently reported injuries encountered in each discipline, with focused discussions of higher risk activities. Some of these higher risk activities include blows to the head and choking or submission movements that may cause concussions or significant head injuries. The roles of rule changes, documented benefits of protective equipment, and changes in training recommendations in attempts to reduce injury are critically assessed. This information is intended to help pediatric health care providers counsel patients and families in encouraging safe participation in martial arts.

Evidence for Acute Electrophysiological and Cognitive Changes Following Routine Soccer Heading.

INTRODUCTION: There is growing concern around the effects of concussion and sub-concussive impacts in sport. Routine game-play in soccer involves intentional and repeated head impacts through ball heading. Although heading is frequently cited as a risk to brain health, little data exist regarding the consequences of this activity. This study aims to assess the immediate outcomes of routine football heading using direct and sensitive measures of brain function. METHODS: Nineteen amateur football players (5 females; age 22±3y) headed machine-projected soccer balls at standardized speeds, modelling routine soccer practice. The primary outcome measure of corticomotor inhibition measured using transcranial magnetic stimulation, was assessed prior to heading and repeated immediately, 24h, 48h and 2weeks post-heading. Secondary outcome measures were cortical excitability, postural control, and cognitive function. RESULTS: Immediately following heading an increase in corticomotor inhibition was detected; further to these electrophysiological alterations, measurable reduction memory function were also found. These acute changes appear transient, with values normalizing 24h post-heading. DISCUSSION: Sub-concussive head impacts routine in soccer heading are associated with immediate, measurable electrophysiological and cognitive impairments. Although these changes in brain function were transient, these effects may signal direct consequences of routine soccer heading on (long-term) brain health which requires further study.

Concussion in Sports: What Do Orthopaedic Surgeons Need to Know?

A concussion is a relatively common sports-related injury that affects athletes of all ages. Although orthopaedic surgeons are not expected to replace sports medicine physicians and neurologists with regard to the management of concussions, orthopaedic surgeons, particularly those who are fellowship-trained in sports medicine, must have a current knowledge base of what a concussion is, how a concussion is diagnosed, and how a concussion should be managed. Orthopaedic surgeons should understand the pathophysiology, assessment, and management of concussion so that they have a basic comprehension of this injury, which is at the forefront of the academic literature and North American media. This understanding will prepare orthopaedic surgeons to work in concert with and assist sports medicine physicians, athletic trainers, and physical therapists in providing comprehensive care for athletes with a concussion.

Assessing Quantitative Changes in Intrinsic Thalamic Networks in Blast and Nonblast Mild Traumatic Brain Injury: Implications for Mechanisms of Injury.

In the global war on terror, the increased use of improvised explosive devices has resulted in increased incidence of blast-related mild traumatic brain injury (mTBI). Diagnosing mTBI is both challenging and controversial due to heterogeneity of injury location, trauma intensity, transient symptoms, and absence of focal biomarkers on standard clinical imaging modalities. The goal of this study is to identify a brain biomarker that is sensitive to mTBI injury. Research suggests the thalamus may be sensitive to changes induced by mTBI. A significant number of connections to and from various brain regions converge at the thalamus. In addition, the thalamus is involved in information processing, integration, and regulation of specific behaviors and mood. In this study, changes in task-free thalamic networks as quantified by graph theory measures in mTBI blast (N = 186), mTBI nonblast (N = 80), and controls (N = 21) were compared. Results show that the blast mTBI group had significant hyper-connectivity compared with the controls and nonblast mTBI group. However, after controlling for post-traumatic stress symptoms (PTSS), the blast mTBI group was not different from the controls, but the nonblast mTBI group showed significant hypo-connectivity. The results suggest that there are differences in the mechanisms of injury related to mTBI as reflected in the architecture of the thalamic networks. However, the effect of PTSS and its relationship to mTBI is difficult to distinguish and warrants more research.

The Role of Nutritional Supplements in Sports Concussion Treatment.

There has been considerable research conducted in regard to the prevention and treatment of concussions. Numerous supplements and vitamins are being used throughout the country to help patients recover from concussions; however, to date, there are no completed human-based studies specifically examining supplement and vitamin use for the treatment or prevention of concussions. This article examines the most current evidence regarding supplements and vitamins for the treatment and prevention of concussions. The supplements and vitamins reviewed include omega-3 fatty acids, curcumin, resveratrol, melatonin, creatine, and Scutellaria baicalensis.

Concussion Management Practice Patterns Among Sports Medicine Physicians.

OBJECTIVE: The primary purpose of this study was to examine concussion management practice patterns among sports medicine physicians in the United States. DESIGN: Cross-sectional study using a web-based survey. PARTICIPANTS: Members of the American Medical Society for Sports Medicine (AMSSM). MAIN OUTCOME MEASURES: We distributed a questionnaire to physician members of the AMSSM assessing the current practices for evaluating and managing concussions sustained during sports. Specifically, we asked respondents about their use of management guidelines, medications, balance assessments, neuropsychological tests, and return-to-play strategies. RESULTS: Of the 3591 members emailed, 425 (11.8%) respondents responded. Ninety-seven percent of respondents reported basing current management of sport-related concussion on a published set of criteria, with a majority (91.9%) following the guidelines provided by the Fourth International Conference on Concussion in Sport. Seventy-six percent of respondents reported using medication beyond 48 hours postinjury. Acetaminophen was reported as the most commonly administered medication, although tricyclic antidepressants and amantadine were also commonly administered. Vitamins, minerals, and dietary supplements were also reported as commonly administered. Most respondents reported using a form of neuropsychological testing (87.1%). A majority of respondents (88.6%) reported allowing athletes to return to competition after concussion only once the athlete becomes symptom free and completes a return-to-play protocol. CONCLUSIONS: Most sports medicine physicians seem to use recently developed guidelines for concussion management, regularly use medications and neuropsychological testing in management strategies, and follow established return-to-play guidelines. CLINICAL RELEVANCE: Sports medicine physicians seem to have clinical expertise in the management of sport-related concussion.

Head Trauma in Mixed Martial Arts.

BACKGROUND: Mixed martial arts (MMA) is a full combative sport with a recent global increase in popularity despite significant scrutiny from medical associations. To date, the empirical research of the risk of head injuries associated with this sport is limited. Youth and amateur participation is growing, warranting investigation into the burden and mechanism of injuries associated with this sport. PURPOSE: (1) To determine the incidence, risk factors, and characteristics of knockouts (KOs) and technical knockouts (TKOs) from repetitive strikes in professional MMA; and (2) to identify the mechanisms of head trauma and the situational factors that lead to KOs and TKOs secondary to repetitive strikes through video analysis. STUDY DESIGN: Descriptive epidemiology study. METHODS: Competition data and video records for all KOs and TKOs from numbered Ultimate Fighting Championship MMA events (n = 844) between 2006 to 2012. Analyses included (1) multivariate logistic regression to investigate factors associated with an increased risk of sustaining a KO or TKO secondary to repetitive strikes and (2) video analysis of all KOs and TKOs secondary to repetitive strikes with descriptive statistics. RESULTS: During the study period, the KO rate was 6.4 per 100 athlete-exposures (AEs) (12.7% of matches), and the rate of TKOs secondary to repetitive strikes was 9.5 per 100 AEs (19.1% of matches), for a combined incidence of match-ending head trauma of 15.9 per 100 AEs (31.9% of matches). Logistic regression identified that weight class, earlier time in a round, earlier round in a match, and older age were risk factors for both KOs and TKOs secondary to repetitive strikes. Match significance and previously sustained KOs or TKOs were also risk factors for KOs. Video analysis identified that all KOs were the result of direct impact to the head, most frequently a strike to the mandibular region (53.9%). The average time between the KO-strike and match stoppage was 3.5 seconds (range, 0-20 seconds), with losers sustaining an average of 2.6 additional strikes (range, 0-20 strikes) to the head. For TKOs secondary to strikes, in the 30-second interval immediately preceding match stoppage, losers sustained, on average, 18.5 strikes (range, 5-46 strikes), with 92.3% of these being strikes to the head. CONCLUSION: Rates of KOs and TKOs in MMA are higher than previously reported rates in other combative and contact sports. Public health authorities and physicians should be cognizant of the rates and mechanisms of head trauma. Preventive measures to lessen the risks of head trauma for those who elect to participate in MMA are described.

[Repeated head injury during judo practice].

Mild traumatic brain injuries, if repeated, can cause permanent brain damage, or even death. I examined five published documents(three judicial decisions, one official injury report, and one book)to analyze incidents in which high school students who, while practicing judo, experienced acute subdural hematoma(ASDH)with grave outcomes, despite the fact that they had been examined by neurosurgeons. The five students, first-grade boy and girl of junior high school and two first-grade boys and one second-grade girl of senior high school, were hit on the head during extracurricular judo practice and were taken to the neurosurgery department of different hospitals. They were all novices or unskilled players. The initial diagnoses were ASDH in three cases, concussion in one, and headache in one. Although the surgeons, except in one case, prohibited the students from returning to play, the juveniles resumed judo practice soon. Some of them complained of continued headaches, but they kept practicing. Between 17 and 82 days after the first injury, they received the fateful hits to their heads, and they were brought to the emergency rooms. MRI and CT revealed ASDH in all;two of them died, and the other three remain in persistent vegetative state. Neurosurgeons should take the initiative to prevent severe brain injury of young athletes through collaborations with the athletes themselves, fellow athletes, family members, coaches, teachers, athletic directors, and other physicians. They should pay close attention to headaches and other signs and symptoms of concussion and prohibit the athletes from returning to play until they are confirmed to be symptom free for recommended periods, insisting that safety comes first.