Diffusion measures indicate fight exposure-related damage to cerebral white matter in boxers and mixed martial arts fighters

Brain trauma characteristics for lightweight and heavyweight fighters in professional mixed martial arts

Mixed martial arts (MMA) is a sport where the fighters are at high risk of brain trauma, with characteristics, such as the frequency, magnitude, and interval of head impacts influencing the risk of developing short- and long-term negative brain health outcomes. These characteristics may be influenced by weight class as they may have unique fighting styles. The purpose of this research was to compare frequency, magnitude, and interval of head impacts between lightweight and heavyweight fighters in professional MMA. Frequency, interval, event type, velocity, and location of head impacts were documented for 60 fighters from 15 Lightweight and 15 Heavyweight professional MMA fights. Head impact reconstructions of these events were performed using physical and finite element modelling methods to determine the strain in the brain tissues. The results found that LW and HW fighters sustained similar head impact frequencies and intervals. The LW fighters sustained a significantly higher frequency of very low and high magnitude impacts to the head from punches; HW a larger frequency of high category strains from elbow strikes. These brain trauma profiles reflect different fight strategies and may inform methods to manage and mitigate the long-term effects of repetitive impacts to the head.

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.

Cranio-Maxillofacial Injuries in Mixed Martial Arts

PURPOSE

To describe a case of a maxillofacial trauma that occurred during a mixed martial arts (MMA) match and to perform a literature review of maxillofacial injuries related to MMA match to determine whether preventive models are applicable.

METHODS

The authors described a maxillofacial injury with orbital and optic nerve involvement that happened during a professional MMA match. A literature review on maxillofacial trauma in MMA was conducted on Scopus and Pubmed with specific keywords.

RESULTS

Open reduction and internal fixation of the maxillofacial complex fractures with right eye optic neuropathy following an MMA match is described. Six articles were selected for the description of trauma in the maxillofacial complex associated with MMA fights.

DISCUSSION

Literature has paid little attention to injuries during MMA matches. The most common injury locations that emerged from the literature review were the head, face, and neck. Middle facial third injuries were the most common type. Frequently the injury involved the ophthalmic area.

CONCLUSIONS

The timing of maxillofacial trauma in MMA is critical. Protective devices should be strongly promoted to prevent catastrophic consequences.

Examining the occurrence and outcomes of concussion and mTBI in mixed martial arts athletes: a systematic review

INTRODUCTION

Mixed martial arts (MMA) is a sport growing in popularity around the world. However, many individuals participate in the sport with little understanding of the potential short- and long-term consequences of injuries sustained while participating. Specifically, individuals are placed at a high risk of minor traumatic brain injury (mTBI) and concussive episodes as a result of head injuries incurred during training and competition.

AIMS

The current review aimed to examine the literature surrounding the occurrence and outcomes of mTBI in MMA athletes to gain a better understanding of these consequences.

METHODS

Twenty-five studies were identified within the current review, of which 14 examined occurrence of mTBI within the sport setting, and elevenidentified outcomes of injury.

RESULTS

Overall, studies found that MMA athletes experienced mTBI and concussion to a greater extent than athletes in other sports. Deficits in memory, reaction time and processing speed were identified following occurrence of mTBI; however, several gaps in outcome measurement were identified within the current literature, including a lack of focus on speech and language outcomes.

CONCLUSION

Future research should examine a wider variety of outcomes to provide a clearer understanding of the consequences of participating in the sport.

Sparring and the Brain: The Associations between Sparring and Regional Brain Volumes in Professional Mixed Martial Arts Fighters

BACKGROUND

Mixed martial arts (MMA) fighters, due to exposure to repetitive head impacts, are at risk for brain atrophy and neurodegenerative sequelae. Simultaneously, motor skills training and cognition-rich activities have been linked with larger regional brain volumes. The majority of an MMA fighter's sporting activity occurs during practice (e.g., sparring) rather than formal competition. This study, therefore, aims to be the first to explore regional brain volumes associated with sparring in MMA fighters.

METHODS

Ninety-four active, professional MMA fighters from the Professional Fighters Brain Health Study met inclusion criteria for this cross-sectional analysis. Adjusted multivariable regression analyses were utilized to examine the relationship between the number of sparring practice rounds per week during typical training and a select number of regional brain volumes (i.e., caudate, thalamus, putamen, hippocampus, amygdala).

RESULTS

A higher number of weekly sparring rounds during training was significantly associated with larger left (beta = 13.5 µL/round, 95% CI 2.26-24.8) and right (beta = 14.9 µL/round, 95% CI 3.64-26.2) caudate volumes. Sparring was not significantly associated with left or right thalamus, putamen, hippocampus, or amygdala volumes.

CONCLUSIONS

More weekly rounds of sparring was not significantly associated with smaller volumes in any of the brain regions studied in active, professional MMA fighters. Sparring's significant association with larger caudate volume raises questions about whether fighters who spar more experience attenuated trauma-related decreases in caudate volume relative to fighters who spar less, whether fighters who spar more experience minimal or even positive changes to caudate volume, whether baseline differences in caudate size may have mediated results, or whether some other mechanism may be at play. Given limitations inherent to the cross-sectional study design, more research is needed to further explore the brain effects of sparring in MMA.

7T MRI Versus 3T MRI of the Brain in Professional Fighters and Patients With Head Trauma

Many studies have investigated the imaging sequelae of repetitive head trauma with mixed results, particularly with regard to the detection of intracranial white matter changes (WMCs) and cerebral microhemorrhages (CMHs) on ≤3 Tesla (T) field magnetic resonance imaging (MRI). 7T MRI, which has recently been approved for clinical use, is more sensitive at detecting lesions associated with multiple neurological diagnoses. In this study, we sought to determine whether 7T MRI would detect more WMCs and CMHs than 3T MRI in 19 professional fighters, 16 patients with single TBI, versus 82 normal healthy controls (NHCs). Fighters and patients with TBI underwent both 3T and 7T MRI; NHCs underwent either 3T (n = 61) or 7T (n = 21) MRI. Readers agreed on the presence/absence of WMCs in 88% (84 of 95) of 3T MRI studies (Cohen's kappa, 0.76) and in 93% (51 of 55) of 7T MRI studies (Cohen's kappa, 0.79). Readers agreed on the presence/absence of CMHs in 96% (91 of 95) of 3T MRI studies (Cohen's kappa, 0.76) and in 96% (54 of 56) of 7T MRI studies (Cohen's kappa, 0.88). The number of WMCs detected was greater in fighters and patients with TBI than NHCs at both 3T and 7T. Moreover, the number of WMCs was greater at 7T than at 3T for fighters, patients with TBI, and NHCs. There was no difference in the number of CMHs detected with 7T MRI versus 3T MRI or in the number of CMHs observed in fighters/patients with TBI versus NHCs. These initial findings suggest that fighters and patients with TBI may have more WMCs than NHCs and that the improved voxel size and signal-to-noise ratio at 7T may help to detect these changes. As 7T MRI becomes more prevalent clinically, larger patient populations should be studied to determine the cause of these WMCs.

Combat Sports as a Model for Measuring the Effects of Repeated Head Impacts on Autonomic Brain Function: A Brief Report of Pilot Data

Automated pupil light reflex (PLR) is a valid indicator of dysfunctional autonomic brain function following traumatic brain injury. PLR's use in identifying disturbed autonomic brain function following repeated head impacts without outwardly visible symptoms has not yet been examined. As a combat sport featuring repeated 'sub-concussive' head impacts, mixed martial arts (MMA) sparring may provide a model to understand such changes. The aim of this pilot study was to explore which, if any, PLR variables are affected by MMA sparring. A cohort of n = 7 MMA athletes (age = 24 ± 3 years; mass = 76.5 ± 9 kg; stature = 176.4 ± 8.5 cm) took part in their regular sparring sessions (eight rounds × 3 min: 1 min recovery). PLR of both eyes was measured immediately pre- and post-sparring using a Neuroptic NPi-200. Bayesian paired samples t-tests (BF₁₀ ≥ 3) revealed decreased maximum pupil size (BF₁₀ = 3), decreased minimum pupil size (BF₁₀ = 4) and reduced PLR latency (BF₁₀ = 3) post-sparring. Anisocoria was present prior to sparring and increased post-sparring, with both eyes having different minimum and maximum pupil sizes (BF₁₀ = 3-4) and constriction velocities post-sparring (BF₁₀ = 3). These pilot data suggest repeated head impacts may cause disturbances to autonomic brain function in the absence of outwardly visible symptoms. These results provide direction for cohort-controlled studies to formally investigate the potential changes observed.

Decreased myelin proteins in brain donors exposed to football-related repetitive head impacts

American football players and other individuals exposed to repetitive head impacts can exhibit a constellation of later-life cognitive and neuropsychiatric symptoms. While tau-based diseases such as chronic traumatic encephalopathy can underpin certain symptoms, contributions from non-tau pathologies from repetitive head impacts are increasingly recognized. We examined cross-sectional associations between myelin integrity using immunoassays for myelin-associated glycoprotein and proteolipid protein 1 with risk factors and clinical outcomes in brain donors exposed to repetitive head impacts from American football. Immunoassays for myelin-associated glycoprotein and proteolipid protein 1 were conducted on dorsolateral frontal white matter tissue samples of 205 male brain donors. Proxies of exposure to repetitive head impacts included years of exposure and age of first exposure to American football play. Informants completed the Functional Activities Questionnaire, Behavior Rating Inventory of Executive Function-Adult Version (Behavioral Regulation Index), and Barratt Impulsiveness Scale-11. Associations between myelin-associated glycoprotein and proteolipid protein 1 with exposure proxies and clinical scales were tested. Of the 205 male brain donors who played amateur and professional football, the mean age was 67.17 (SD = 16.78), and 75.9% (n = 126) were reported by informants to be functionally impaired prior to death. Myelin-associated glycoprotein and proteolipid protein 1 correlated with the ischaemic injury scale score, a global indicator of cerebrovascular disease (r = -0.23 and -0.20, respectively, Ps < 0.01). Chronic traumatic encephalopathy was the most common neurodegenerative disease (n = 151, 73.7%). Myelin-associated glycoprotein and proteolipid protein 1 were not associated with chronic traumatic encephalopathy status, but lower proteolipid protein 1 was associated with more severe chronic traumatic encephalopathy (P = 0.03). Myelin-associated glycoprotein and proteolipid protein 1 were not associated with other neurodegenerative disease pathologies. More years of football play was associated with lower proteolipid protein 1 [beta = -2.45, 95% confidence interval (CI) [-4.52, -0.38]] and compared with those who played <11 years of football (n = 78), those who played 11 or more years (n = 128) had lower myelin-associated glycoprotein (mean difference = 46.00, 95% CI [5.32, 86.69]) and proteolipid protein 1 (mean difference = 24.72, 95% CI [2.40, 47.05]). Younger age of first exposure corresponded to lower proteolipid protein 1 (beta = 4.35, 95% CI [0.25, 8.45]). Among brain donors who were aged 50 or older (n = 144), lower proteolipid protein 1 (beta = -0.02, 95% CI [-0.047, -0.001]) and myelin-associated glycoprotein (beta = -0.01, 95% CI [-0.03, -0.002]) were associated with higher Functional Activities Questionnaire scores. Lower myelin-associated glycoprotein correlated with higher Barratt Impulsiveness Scale-11 scores (beta = -0.02, 95% CI [-0.04, -0.0003]). Results suggest that decreased myelin may represent a late effect of repetitive head impacts that contributes to the manifestation of cognitive symptoms and impulsivity. Clinical-pathological correlation studies with prospective objective clinical assessments are needed to confirm our findings.

Deep Grey Matter Volume is Reduced in Amateur Boxers as Compared to Healthy Age-matched Controls

Purpose

Mild traumatic brain injuries (mTBI) sustained during contact sports like amateur boxing are found to have long-term sequelae, being linked to an increased risk of developing neurological conditions like Parkinson’s disease. The aim of this study was to assess differences in volume of anatomical brain structures between amateur boxers and control subjects with a special interest in the affection of deep grey matter structures.

Methods

A total of 19 amateur boxers and 19 healthy controls (HC), matched for age and intelligence quotient (IQ), underwent 3T magnetic resonance imaging (MRI) as well as neuropsychological testing. Body mass index (BMI) was evaluated for every subject and data about years of boxing training and number of fights were collected for each boxer. The acquired 3D high resolution T1 weighted MR images were analyzed to measure the volumes of cortical grey matter (GM), white matter (WM), cerebrospinal fluid (CSF) and deep grey matter structures. Multivariate analysis was applied to reveal differences between groups referencing deep grey matter structures to normalized brain volume (NBV) to adjust for differences in head size and brain volume as well as adding BMI as cofactor.

Results

Total intracranial volume (TIV), comprising GM, WM and CSF, was lower in boxers compared to controls (by 7.1%, P = 0.009). Accordingly, GM (by 5.5%, P = 0.038) and WM (by 8.4%, P = 0.009) were reduced in boxers. Deep grey matter showed statistically lower volumes of the thalamus (by 8.1%, P = 0.006), caudate nucleus (by 11.1%, P = 0.004), putamen (by 8.1%, P = 0.011), globus pallidus (by 9.6%, P = 0.017) and nucleus accumbens (by 13.9%, P = 0.007) but not the amygdala (by 5.5%, P = 0.221), in boxers compared to HC.

Conclusion

Several deep grey matter structures were reduced in volume in the amateur boxer group. Furthermore, longitudinal studies are needed to determine the damage pattern affecting deep grey matter structures and its neuropsychological relevance.

Concussion vs. resignation by submission: Technical–tactical behavior analysis considering injury in mixed martial arts

This research study verified the technical–tactical actions during the mixed martial arts (MMA) fights to generate serious enough injury to stop the MMA round, determining technical-tactical potential risk factors for injury in official MMA combats, according to Concussion or Resignation per Submission. A total of 990 rounds with concussions and 627 resignations per submission were considered with severe injury (i.e., a fight ended by a doctor or referee). All injuries were diagnosed and managed by attending ringside physicians during the MMA fights and rounds and had a continuous technical–tactical behavior analysis, p ≤ 0.05. The leading cause of concussion was due to head trauma (~90%), with higher dependence on head strikes scored actions. Comparisons between Concussion and Resignation per Submission combats demonstrated differences between distance head strikes actions [13(6,25) vs. 9(4,18) frequencies], clinch head strikes actions [1(0;4) vs. 1(0;3) frequencies], ground head strikes actions [1(0;8) vs. 2(0;10) frequencies] and takedowns actions [0(0;1) vs. 1(0;2) frequencies]. This information may provide significant evidence regarding the doctor stoppage in concussion combats and when it could be called by officials supervising MMA.

White matter abnormalities characterize the acute stage of sports-related mild traumatic brain injury

Sports-related concussion, a form of mild traumatic brain injury, is characterized by transient disturbances of brain function. There is increasing evidence that functional brain changes may be driven by subtle abnormalities in white matter microstructure, and diffusion MRI has been instrumental in demonstrating these white matter abnormalities in vivo. However, the reported location and direction of the observed white matter changes in mild traumatic brain injury are variable, likely attributable to the inherent limitations of the white matter models used. This cross-sectional study applies an advanced and robust technique known as fixel-based analysis to investigate fibre tract-specific abnormalities in professional Australian Football League players with a recent mild traumatic brain injury. We used the fixel-based analysis framework to identify common abnormalities found in specific fibre tracts in participants with an acute injury (≤12 days after injury; n = 14). We then assessed whether similar changes exist in subacute injury (&gt;12 days and &lt;3 months after injury; n = 15). The control group was 29 neurologically healthy control participants. We assessed microstructural differences in fibre density and fibre bundle morphology and performed whole-brain fixel-based analysis to compare groups. Subsequent tract-of-interest analyses were performed within five selected white matter tracts to investigate the relationship between the observed tract-specific abnormalities and days since injury and the relationship between these tract-specific changes with cognitive abnormalities. Our whole-brain analyses revealed significant increases in fibre density and bundle cross-section in the acute mild traumatic brain injury group when compared with controls. The acute mild traumatic brain injury group showed even more extensive differences when compared with the subacute injury group than with controls. The fibre structures affected in acute concussion included the corpus callosum, left prefrontal and left parahippocampal white matter. The fibre density and cross-sectional increases were independent of time since injury in the acute injury group, and were not associated with cognitive deficits. Overall, this study demonstrates that acute mild traumatic brain injury is characterized by specific white matter abnormalities, which are compatible with tract-specific cytotoxic oedema. These potential oedematous changes were absent in our subacute mild traumatic brain injury participants, suggesting that they may normalize within 12 days after injury, although subtle abnormalities may persist in the subacute stage. Future longitudinal studies are needed to elucidate individualized recovery after brain injury.

Neuroimaging in professional combat sports: consensus statement from the association of ringside physicians

Professional boxing, kickboxing, and mixed martial arts (MMA) are popular sports with substantial risk for both acute and chronic traumatic brain injury (TBI). Although rare, combat sports athletes have died in the ring or soon after the completion of a bout. Deaths in these instances are usually the result of an acute catastrophic neurological event such as an acute subdural hematoma (SDH). Other causes may include acute epidural hematoma (EDH), subarachnoid hemorrhage (SAH), intraparenchymal hemorrhage (IPH), or a controversial, rare, and still disputed clinical entity called second-impact syndrome (SIS). Neuroimaging or brain imaging is currently included in the process of registering for a license to compete in combat sports in some jurisdictions of the United States of America and around the world. However, the required imaging specifics and frequency vary with no consensus guidelines. The Association of Ringside Physicians (an international, nonprofit organization dedicated to the health and safety of the combat sports athlete) sets forth this consensus statement to establish neuroimaging guidelines in combat sports. Commissions, ringside physicians, combat sports athletes, trainers, promoters, sanctioning bodies, and other healthcare professionals can use this statement for risk stratification of a professional combat sports athlete prior to licensure, identifying high-risk athletes and for prognostication of the brain health of these athletes over the course of their career. Guidelines are also put forth regarding neuroimaging requirements in the immediate aftermath of a bout.

Exploratory Systematic Review of Mixed Martial Arts: An Overview of Performance of Importance Factors with over 20,000 Athletes

This review aimed to analyze the findings in the literature related to Mixed Martial Arts (MMA) through an exploratory systematic review and to present the state of the art from a multifactorial perspective. The review was conducted in accordance with the PRISMA statement, with a search performed in the Scopus, PubMed, and Web of Science databases. Participants were competitive athletes (amateurs or professionals) of regional, national, or international levels. Of the 2763 registries identified, 112 studies met the eligibility criteria. The pooled sample size and age were 20,784 participants, with a mean age of 27.7 ± 6 years for male and 28.9 ± 3 years for female, with the vast majority of athletes being male (94.9%). MMA athletes were 17.2% amateurs, 73.8% professionals, and 9% were not reported. The scientific literature related to MMA reported injuries (n = 28), weight loss (n = 21), technical and tactical analysis (n = 23), physical fitness (n = 8), physiological responses and training characteristics (n = 13), psychobiological parameters (n = 12), and interventions applied to MMA athletes (n = 7). Therefore, this exploratory systematic review presents practitioners and researchers with seven broad summaries of each facet of performance of importance in this population of athletes.

Head injury in mixed martial arts: a review of epidemiology, affected brain structures and risks of cognitive decline

Background: The popularity trend of mixed martial arts (MMA) is steeply increasing, especially in the very young population. Unfortunately, MMA carries an enormous risk of head trauma.Purpose: The aim of this article is to provide review of studies on the association between head injuries and cognitive functions in MMA fighters.Methods: A systematic literature review was performed. Web of Science, PubMed, Springer, and Scopus databases were used. A total of 30 studies were identified. The inclusion criteria were as follows: studies with MMA fighters and head injuries and/or TKO/KO and/or reduction of cognitive functions in these fighters.Results: The results indicate that the incidence of head traumas ranges between 58% and 78% of all injuries. The King-Devick test seems to be a suitable rapid tool used in the studies to assess the extent of cognitive impairment. Among the detected studies, the post-fighting scores were significantly worse for fighters with head trauma during the match. We also found anomalies in MMA fighters in different brain structures, but it seems that the thalamus and caudate are the most affected. The impaired performance in processing speed, verbal memory and psychomotor speed is regularly confirmed in studies with MMA fighters. In addition, head traumatization seems to be a risk factor for the development of neurodegenerative disorders and it may be one of the possible causes of chronic traumatic encephalopathy (CTE). Several global medical societies have identified MMA as a violent and dangerous sport and have called for its ban - but unsuccessfully.Conclusion: Therefore, possible recommendations should include increased medical supervision of the fighter (during his career, but also after it) and the introduction of practical safety instructions for fighters to reduce the risk of developing CTE. With the increasing popularity of MMA, the risk of CTE should not be underestimated.

White matter abnormalities in active elite adult rugby players

The recognition, diagnosis and management of mild traumatic brain injuries are difficult and confusing. It is unclear how the severity and number of injuries sustained relate to brain injuries, such as diffuse axonal injury, diffuse vascular injury and progressive neurodegeneration. Advances in neuroimaging techniques enable the investigation of neuropathologies associated with acute and long-term effects of injury. Head injuries are the most commonly reported injury seen during professional rugby. There is increased vigilance for the immediate effects of these injuries in matches, but there has been surprisingly little research investigating the longer-term effects of rugby participation. Here, we present a longitudinal observational study investigating the relationship of exposure to rugby participation and sub-acute head injuries in professional adult male and female rugby union and league players using advanced MRI. Diffusion tensor imaging and susceptibility weighted imaging was used to assess white matter structure and evidence of axonal and diffuse vascular injury. We also studied changes in brain structure over time using Jacobian Determinant statistics extracted from serial volumetric imaging. We tested 41 male and 3 female adult elite rugby players, of whom 21 attended study visits after a head injury, alongside 32 non-sporting controls, 15 non-collision-sport athletic controls and 16 longitudinally assessed controls. Eighteen rugby players participated in the longitudinal arm of the study, with a second visit at least 6 months after their first scan. Neuroimaging evidence of either axonal injury or diffuse vascular injury was present in 23% (10/44) of players. In the non-acutely injured group of rugby players, abnormalities of fractional anisotropy and other diffusion measures were seen. In contrast, non-collision-sport athletic controls were not classified as showing abnormalities. A group level contrast also showed evidence of sub-acute injury using diffusion tensor imaging in rugby players. Examination of longitudinal imaging revealed unexpected reductions in white matter volume in the elite rugby players studied. These changes were not related to self-reported head injury history or neuropsychological test scores and might indicate excess neurodegeneration in white matter tracts affected by injury. Taken together, our findings suggest an association of participation in elite adult rugby with changes in brain structure. Further well-designed large-scale studies are needed to understand the impact of both repeated sports-related head impacts and head injuries on brain structure, and to clarify whether the abnormalities we have observed are related to an increased risk of neurodegenerative disease and impaired neurocognitive function following elite rugby participation.

A preliminary investigation of corpus callosum subregion white matter vulnerability and relation to chronic outcome in boxers

Microstructural neuropathology occurs in the corpus callosum (CC) after repetitive sports concussion in boxers and can be dose-dependent. However, the specificity and relation of CC changes to boxing exposure extent and post-career psychiatric and neuropsychological outcomes are largely unknown. Using deterministic diffusion tensor imaging (DTI) techniques, boxers and demographically-matched, noncontact sport athletes were compared to address literature gaps. Ten boxers and 9 comparison athletes between 26 and 59 years old (M = 44.63, SD = 9.24) completed neuropsychological testing and MRI. Quantitative DTI metrics were estimated for CC subregions. Group×Region interaction effects were observed on fractional anisotropy (FA; η²_p ≥ .21). Follow-up indicated large effects of group (η²_p ≥ .26) on splenium FA (boxers<comparisons) and genu mean diffusivity (MD; boxers>comparisons), but not radial diffusivity (RD). The group of boxers had moderately elevated number of psychiatric symptoms and reduced neuropsychological scores relative to the comparison group. In boxers, years sparring, professional bouts, and knockout history correlated strongly (r > |.40|) with DTI metrics and fine motor dexterity. In the comparison group, splenium FA correlated positively with psychiatric symptoms. In the boxer group, neuropsychological scores correlated with DTI metrics in all CC subregions. Results suggested relative vulnerability of the splenium and, to a lesser extent, the genu to chronic, repetitive head injury from boxing. Dose-dependent associations of professional boxing history extent with DTI white matter structure indices as well as fine motor dexterity were supported. Results indicated that symptoms of depression and executive dysfunction may provide the strongest indicators of global CC disruption from boxing.

The role of salivary vesicles as a potential inflammatory biomarker to detect traumatic brain injury in mixed martial artists

Traumatic brain injury (TBI) is of significant concern in the realm of high impact contact sports, including mixed martial arts (MMA). Extracellular vesicles (EVs) travel between the brain and oral cavity and may be isolated from salivary samples as a noninvasive biomarker of TBI. Salivary EVs may highlight acute neurocognitive or neuropathological changes, which may be particularly useful as a biomarker in high impact sports. Pre and post-fight samples of saliva were isolated from 8 MMA fighters and 7 from controls. Real-time PCR of salivary EVs was done using the TaqMan Human Inflammatory array. Gene expression profiles were compared pre-fight to post-fight as well as pre-fight to controls. Largest signals were noted for fighters sustaining a loss by technical knockout (higher impact mechanism of injury) or a full match culminating in referee decision (longer length of fight), while smaller signals were noted for fighters winning by joint or choke submission (lower impact mechanism as well as less time). A correlation was observed between absolute gene information signals and fight related markers of head injury severity. Gene expression was also significantly different in MMA fighters pre-fight compared to controls. Our findings suggest that salivary EVs as a potential biomarker in the acute period following head injury to identify injury severity and can help elucidate pathophysiological processes involved in TBI.

Association of Cavum Septum Pellucidum and Cavum Vergae With Cognition, Mood, and Brain Volumes in Professional Fighters

Importance

Many studies have investigated the imaging findings showing sequelae of repetitive head trauma, with mixed results.

Objective

To determine whether fighters (boxers and mixed martial arts fighters) with cavum septum pellucidum (CSP) and cavum vergae (CV) have reduced volumes in various brain structures or worse clinical outcomes on cognitive and mood testing.

Design, Setting, and Participants

This cohort study assessed participants from the Professional Fighters Brain Health Study. Data were collected from April 14, 2011, to January 17, 2018, and were analyzed from September 1, 2018, to May 23, 2019. This study involved a referred sample of 476 active and retired professional fighters. Eligible participants were at least 18 years of age and had at least a fourth-grade reading level. Healthy age-matched controls with no history of trauma were also enrolled.

Exposures

Presence of CSP, CV, and their total (additive) length (CSPV length).

Main Outcomes and Measures

Information regarding depression, impulsivity, and sleepiness among study participants was obtained using the Patient Health Questionnaire depression scale, Barrett Impulsiveness Scale, and the Epworth Sleepiness Scale. Cognition was assessed using raw scores from CNS Vital Signs. Volumes of various brain structures were measured via magnetic resonance imaging.

Results

A total of 476 fighters (440 men, 36 women; mean [SD] age, 30.0 [8.2] years [range, 18-72 years]) and 63 control participants (57 men, 6 women; mean [SD] age, 30.8 [9.6] years [range, 18-58 years]) were enrolled in the study. Compared with fighters without CV, fighters with CV had significantly lower mean psychomotor speed (estimated difference, -11.3; 95% CI, -17.4 to -5.2; P = .004) and lower mean volumes in the supratentorium (estimated difference, -31 191 mm3; 95% CI, -61 903 to -479 mm3; P = .05) and other structures. Longer CSPV length was associated with lower processing speed (slope, -0.39; 95% CI, -0.49 to -0.28; P < .001), psychomotor speed (slope, -0.43; 95% CI, -0.53 to -0.32; P < .001), and lower brain volumes in the supratentorium (slope, -1072 mm3 for every 1-mm increase in CSPV length; 95% CI, -1655 to -489 mm3; P < .001) and other structures.

Conclusions and Relevance

This study suggests that the presence of CSP and CV is associated with lower regional brain volumes and cognitive performance in a cohort exposed to repetitive head trauma.

Cognitively supernormal older adults maintain a unique structural connectome that is resistant to Alzheimer's pathology

Studying older adults with excellent cognitive capacities (Supernormals) provides a unique opportunity for identifying factors related to cognitive success - a critical topic across lifespan. There is a limited understanding of Supernormals' neural substrates, especially whether any of them attends shaping and supporting superior cognitive function or confer resistance to age-related neurodegeneration such as Alzheimer's disease (AD). Here, applying a state-of-the-art diffusion imaging processing pipeline and finite mixture modelling, we longitudinally examine the structural connectome of Supernormals. We find a unique structural connectome, containing the connections between frontal, cingulate, parietal, temporal, and subcortical regions in the same hemisphere that remains stable over time in Supernormals, relatively to typical agers. The connectome significantly classifies positive vs. negative AD pathology at 72% accuracy in a new sample mixing Supernormals, typical agers, and AD risk [amnestic mild cognitive impairment (aMCI)] subjects. Among this connectome, the mean diffusivity of the connection between right isthmus cingulate cortex and right precuneus most robustly contributes to predicting AD pathology across samples. The mean diffusivity of this connection links negatively to global cognition in those Supernormals with positive AD pathology. But this relationship does not exist in typical agers or aMCI. Our data suggest the presence of a structural connectome supporting cognitive success. Cingulate to precuneus white matter integrity may be useful as a structural marker for monitoring neurodegeneration and may provide critical information for understanding how some older adults maintain or excel cognitively in light of significant AD pathology.

The effect of age of first exposure to competitive fighting on cognitive and other neuropsychiatric symptoms and brain volume

It has long been established that fighting sports such as boxing and mixed martial arts can lead to head injury. Prior work from this group on the Professional Fighters Brain Health Study found that exposure to repetitive head impacts is associated with lower brain volumes and decreased processing speed in fighters. Current and previously licensed professional fighters were recruited, divided into active and retired cohorts, and matched with a control group that had no prior experience in sports with likely head trauma. This study examined the relationship between age of first exposure (AFE) to fighting sports and brain structure (MRI regional volume), cognitive performance (CNS Vital Signs, iComet C3), and clinical neuropsychiatric symptoms (PHQ-9, Barratt Impulsiveness Scale). Brain MRI data showed significant correlations between earlier AFE and smaller bilateral hippocampal and posterior corpus callosum volumes for both retired and active fighters. Earlier AFE in active fighters was correlated with decreased processing speed and decreased psychomotor speed. Retired fighters showed a correlation between earlier AFE and higher measures of depression and impulsivity. Overall, the results help to inform clinicians, governing bodies, parents, and athletes of the risks associated with beginning to compete in fighting sports at a young age.

Understanding white matter structural connectivity differences between cognitively impaired and nonimpaired active professional fighters

Long-term traumatic brain injury due to repeated head impacts (RHI) has been shown to be a risk factor for neurodegenerative disorders, characterized by a loss in cognitive performance. Establishing the correlation between changes in the white matter (WM) structural connectivity measures and neuropsychological test scores might help to identify the neural correlates of the scores that are used in daily clinical setting to investigate deficits due to repeated head blows. Hence, in this study, we utilized high angular diffusion MRI (dMRI) of 69 cognitively impaired and 70 nonimpaired active professional fighters from the Professional Fighters Brain Health Study, and constructed structural connectomes to understand: (a) whether there is a difference in the topological WM organization between cognitively impaired and nonimpaired active professional fighters, and (b) whether graph-theoretical measures exhibit correlations with neuropsychological scores in these groups. A dMRI derived structural connectome was constructed for every participant using brain regions defined in AAL atlas as nodes, and the product of fiber number and average fractional anisotropy of the tracts connecting the nodes as edges. Our study identified a topological WM reorganization due to RHI in fighters prone to cognitive decline that was correlated with neuropsychological scores. Furthermore, graph-theoretical measures were correlated differentially with neuropsychological scores between groups. We also found differentiated WM connectivity involving regions of hippocampus, precuneus, and insula within our cohort of cognitively impaired fighters suggesting that there is a discernible WM topological reorganization in fighters prone to cognitive decline.

A common neural signature of brain injury in concussion and subconcussion

The midbrain is biomechanically susceptible to force loading from repetitive subconcussive head impacts (RSHI), is a site of tauopathy in chronic traumatic encephalopathy (CTE), and regulates functions (e.g., eye movements) often disrupted in concussion. In a prospective longitudinal design, we demonstrate there are reductions in midbrain white matter integrity due to a single season of collegiate football, and that the amount of reduction in midbrain white matter integrity is related to the amount of rotational acceleration to which players' brains are exposed. We then replicate the observation of reduced midbrain white matter integrity in a retrospective cohort of individuals with frank concussion, and further show that variance in white matter integrity is correlated with levels of serum-based tau, a marker of blood-brain barrier disruption. These findings mean that noninvasive structural MRI of the midbrain is a succinct index of both clinically silent white matter injury as well as frank concussion.

A 12-Year Cohort Study of Doc-Stoppage in Professional Mixed Martial Arts

Purposes: To determine actions during bouts that generate serious enough injury to stop the bout; verifying the injury incidence, types, and prevalence of doctor stoppages (doc-stoppage); and identify potential risk factors by analyzing technical-tactical profiles for injury in sanctioned mixed martial arts bouts taking place over a 12-y period. Methods: This research analyzed 440 paired mixed martial arts matches separated by doc-stoppage (n = 220) and no doc-stoppage (n = 220) from 2002 to 2014. Technical knockouts for doc-stoppage were diagnosed and managed by attending ringside doctors, and the time–motion variables were categorized into total combat time separated by low- or high-intensity activities per round, stand-up, or groundwork actions, P ≤ .05. Results: The main cause of injuries in doc-stoppage situations was due to facial injuries (>90%), with 87.1% occurring after striking actions during the second round. Lacerations were the leading type of injury, which occurred with 80% frequency. The results showed differences between doc-stoppage and no doc-stoppage for standing combat with low-intensity actions (130.6 [8.5] s vs 83.3 [6.9] s for first round; 115.7 [10.5] s vs 100.1 [9.6] s for second round, and 121.5 [19.5] s vs 106.3 [11.7] s for third round) and total strike attempts (34.5, 23.0–51.8 vs 25.0, 12.0–40.8); in standing combat, head strike attempts (21, 10–33 vs 11, 4–21) and body strikes (2.5, 1.0–5.8 vs 1.0–2), and in groundwork combat, head strikes landed (0.0–3.0 vs 0.0–5.0). Conclusions: This research showed higher values of strike attempts with 2 main orientations, namely the head (on the ground and in stand-up actions) and body (in stand-up actions), and may provide important information regarding the technical knockout and when it can be called by officials supervising mixed martial arts bouts.

Musculoskeletal and head injuries in the Ultimate Fighting Championship (UFC)

OBJECTIVES

Mixed martial arts (MMA) has witnessed a surge in popularity worldwide. This study explores the musculoskeletal and head injuries sustained in the professional fights of the Ultimate Fighting Championship (UFC), and establishes associations between injury profiles and impactful contributory factors.

METHODS

The Nevada State Athletic Commission database was screened for ringside physician reports of UFC fights between January 2016 and July 2018. Information on the fighter's gender, weight, injury, way of finish, and match result were collected. Injury rates were calculated and statistical analyses were conducted to determine significant associations among variables. P-values <0.05 were considered significant (95% CI).

RESULTS

A total of 291 injuries were recorded in 285 fights from nine weight divisions. The overall injury rate was 51 per 100 athletic exposures (AE). Males predominantly partook in 249 matches (87%) and had higher injury rates (54 injuries per 100 AE) than females (30 injuries per 100 AE). Decision was the most common way a match ended. Knockouts (KOs) were significantly higher in males (36%) than in females (14%, P = 0.0007). Submissions were significantly higher in females (36%) than in males (16%, P = 0.001). Head injuries (67%) were the most common injuries reported with a rate of 34 per 100 AE. Upper limb injuries were significantly higher in females (40%) than in males (14%, P = 0.0003). Lower limb injuries were significantly higher in males (19%) than in females (5%, P = 0.01). Head injuries were significantly associated with KOs (P < 0.0001). Upper limb injuries (P = 0.032) and lower limb injuries (P = 0.034) were significantly associated with matches that ended with Decision. Trend-line analyses showed that as weight division increases, overall injury rates, head injuries, lower limb injuries, and KOs' frequency increase, whereas upper limb injuries, Submission frequency, and Decision frequency decrease.

CONCLUSION

MMA has a high injury rate. Gender, way of finish, and weight play an important role in predicting fight outcomes and injury profiles. Injury prevention policies must be entertained to limit injury risk in MMA.

Concussion management in combat sports: consensus statement from the Association of Ringside Physicians

Various organisations and experts have published numerous statements and recommendations regarding different aspects of sports-related concussion including definition, presentation, treatment, management and return to play guidelines. 1-7 To date, there have been no written consensus statements specific for combat sports regarding management of combatants who have suffered a concussion or for return to competition after a concussion. In combat sports, head contact is an objective of the sport itself. Accordingly, management and treatment of concussion in combat sports should, and must, be more stringent than for non-combat sports counterparts.The Association of Ringside Physicians (an international, non-profit organisation dedicated to the health and safety of the combat sports athlete) sets forth this consensus statement to establish management guidelines that ringside physicians, fighters, referees, trainers, promoters, sanctioning bodies and other healthcare professionals can use in the ringside setting. We also provide guidelines for the return of a combat sports athlete to competition after sustaining a concussion. This consensus statement does not address the management of moderate to severe forms of traumatic brain injury, such as intracranial bleeds, nor does it address the return to competition for combat sports athletes who have suffered such an injury. These more severe forms of brain injuries are beyond the scope of this statement. This consensus statement does not address neuroimaging guidelines in combat sports.

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.

Comparing fMRI activation during smooth pursuit eye movements among contact sport athletes, non-contact sport athletes, and non-athletes

Objectives

Though sub-concussive impacts are common during contact sports, there is little consensus whether repeat blows affect brain function. Using a "lifetime exposure" rather than acute exposure approach, we examined oculomotor performance and brain activation among collegiate football players and two control groups. Our analysis examined whether there are group differences in eye movement behavioral performance and in brain activation during smooth pursuit.

Methods

Data from 21 off-season Division I football "starters" were compared with a) 19 collegiate cross-country runners, and b) 11 non-athlete college students who were SES matched to the football player group (total N = 51). Visual smooth pursuit was performed while undergoing fMRI imaging via a 3 Tesla scanner. Smooth pursuit eye movements to three stimulus difficulty levels were measured with regard to RMS error, gain, and lag.

Results

No meaningful differences were found for any of the standard analyses used to assess smooth pursuit eye movements. For fMRI, greater activation was seen in the oculomotor region of the cerebellar vermis and areas of the FEF for football players as compared to either control group, who did not differ on any measure.

Conclusion

Greater cerebellar activity among football players while performing an oculomotor task could indicate that they are working harder to compensate for some subtle, long-term subconcussive deficits. Alternatively, top athletes in a sport requiring high visual motor skill could have more of their cerebellum and FEF devoted to oculomotor task performance regardless of subconcussive history. Overall, these results provide little firm support for an effect of accumulated subconcussion exposure on brain function.

Safety in Mixed Martial Arts: a 7-Year Review of Cancelled MMA Bouts in Calgary, Alberta, During the Pre-bout Medical Examination Period

BACKGROUND

Presently, there is no literature that examines the reasons for the cancellation of amateur or professional mixed martial arts (MMA) bouts. The purpose of this study was to review the circumstances that lead to the cancellation of MMA bouts by Calgary ringside physicians during the pre-bout examination period and to identify any emerging patterns that may guide the regulatoin of this sport.

METHODS

The case-series  was constructed from the Calgary Combative Sports Commission pre-bout examination records and the medical records submitted by each athlete from January 2010 to December 2016.

RESULTS

Cancelled bouts in the pre-bout examination periods represented 5.4% of all MMA bouts in Calgary. A total of 25 reasons lead to bout cancellation and included the following: failure to obtain required neuroimaging (28.0%), neuroimaging abnormalities (24.0%), incomplete routine screening investigations (16.0%), exceeding maximum weight differential between the two athletes (16.0%), injury in the pre-competition period (8.0%), dehydration (4.0%), and ECG abnormalities (4.0%). The abnormalities on neuroimaging (n of 6) included the following: post traumatic gliosis on MRI (n = 1, 16.7%), flares diffusely and findings consistent with microhemorrhage on MRI (n = 1, 16.7%), chronic orbital fracture with fat pad extrusion on CT (n = 2, 33.3%), lacunar infarct on MRI (1), and unspecified MRI abnormality (n = 1, 16.7%). Twenty-two athletes had bouts cancelled and of these three athletes had their bouts stopped for two reasons.

CONCLUSIONS

The following recommendations are presented and include: the creation of guidelines regarding pre- and post-bout neuroimaging, the implementation of industry-wide minimum medical screening standards, the adoption of a longitudinal approach to weight monitoring, the development of competent ringside physician groups, and active oversight by the Combative Sports Commission during the matchmaking process.

Chronic traumatic encephalopathy: neuroimaging biomarkers

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disorder associated with repetitive head impact exposure, such as that resulting from sports-related concussive and subconcussive brain trauma. Currently, the only way to diagnose CTE is by using neuropathologic markers obtained postmortem. To diagnose CTE earlier, so that possible treatment interventions may be employed, there is a need to develop noninvasive in vivo biomarkers of CTE. Neuroimaging provides promising biomarkers for the diagnosis of CTE and may also help elucidate pathophysiologic changes that occur with chronic sports-related brain injury. To describe the use of neuroimaging as presumed biomarkers of CTE, this chapter focuses on only those studies that report the chronic stages of sports-related brain injury, as opposed to previous chapters that described neuroimaging in the context of acute and subacute injury. Studies using positron emission tomography and magnetic resonance imaging and spectroscopy will be discussed for contact/collision sports such as American football, boxing, mixed martial arts, rugby, and soccer, in which repetitive head impacts are common.

Traumatic brain injuries in mixed martial arts: A systematic review

Introduction

Mixed martial arts is an emerging combat sport that is gaining popularity worldwide. We systematically reviewed the literature regarding the prevalence, severity and risk factors of head injuries sustained in mixed martial arts activities.

Methods

We conducted a comprehensive systematic review of Ovid MEDLINE, Embase, PsycINFO, EBM Reviews, CINAHL, SPORTDiscus, and Web of Science from 1990 to 2016 for studies of any design that reported associations of acute or chronic head injuries in persons participating in mixed martial arts activities.

Results

The initial database search yielded a total 472 citations, including 264 unique citations after duplications were removed. A total of 18 articles, primarily of observational data, showed ‘technical knockouts’ and ‘knockouts’ are prevalent in this sport (range: 28.3–46.2% of all matches) with other studies showing the lifetime average of 6.2 technical knockouts or knockouts in a career. Studies used inconsistent reporting methods for concussion, and no information regarding long-term follow-up was available.

Conclusion

Mixed martial arts fighting may be associated with repetitive head injuries and potential long-term neurological consequences; however, data on this topic are poor. Larger studies and stringent medical oversight are needed to improve the management and understanding of mixed martial arts head injuries, with implementation of harm reduction strategies and/or rule modifications to prevent long-term neurological sequelae. Systematic Review Registration: PROSPERO – CRD42014010019.

Investigating structural and perfusion deficits due to repeated head trauma in active professional fighters

Repeated head trauma experienced by active professional fighters results in various structural, functional and perfusion damage. However, whether there are common regions of structural and perfusion damage due to fighting and whether these structural and perfusion differences are associated with neuropsychological measurements in active professional fighters is still unknown. To that end, T1-weighted and pseudocontinuous arterial spin labeling MRI on a group of healthy controls and active professional fighters were acquired. Voxelwise group comparisons, in a univariate and multivariate sense, were performed to investigate differences in gray and white matter density (GMD, WMD) and cerebral blood flow (CBF) between the two groups. A significantly positive association between global GMD and WMD was obtained with psychomotor speed and reaction time, respectively, in our cohort of active professional fighters. In addition, regional WMD deficit was observed in a cluster encompassing bilateral pons, hippocampus, and thalamus in fighters (0.49 ± 0.04 arbitrary units (a.u.)) as compared to controls (0.51 ± 0.05a.u.). WMD in the cluster of active fighters was also significantly associated with reaction time. Significantly lower CBF was observed in right inferior temporal lobe with both partial volume corrected (46.9 ± 14.93 ml/100 g/min) and non-partial volume corrected CBF maps (25.91 ± 7.99 ml/100 g/min) in professional fighters, as compared to controls (65.45 ± 22.24 ml/100 g/min and 35.22 ± 12.18 ml/100 g/min respectively). A paradoxical increase in CBF accompanying right cerebellum and fusiform gyrus in the active professional fighters (29.52 ± 13.03 ml/100 g/min) as compared to controls (19.43 ± 12.56 ml/100 g/min) was observed with non-partial volume corrected CBF maps. Multivariate analysis with both structural and perfusion measurements found the same clusters as univariate analysis in addition to a cluster in right precuneus. Both partial volume corrected and non-partial volume corrected CBF of the cluster in the thalamus had a significantly positive association with the number of fights. In addition, GMD of the cluster in right precuneus was significantly associated with psychomotor speed in our cohort of active professional fighters. Our results suggest a heterogeneous pattern of structural and CBF deficits due to repeated head trauma in active professional fighters. This finding indicates that investigating both structural and CBF changes in the same set of participants may help to understand the pathophysiology and progression of cognitive decline due to repeated head trauma.

•

Repetitive head trauma revealed no global structural or global perfusion deficits.

•

Cluster of significantly lower WMD was associated with reaction time in fighters.

•

Fighters had lower CBF in right inferior temporal lobe.

•

Multivariate analysis revealed a cluster associated with number of fights.

•

Combined analysis of structural and perfusion measurements is recommended.

What is the Relationship of Traumatic Brain Injury to Dementia?

There is a long history linking traumatic brain injury (TBI) with the development of dementia. Despite significant reservations, such as recall bias or concluding causality for TBI, a summary of recent research points to several conclusions on the TBI-dementia relationship. 1) Increasing severity of a single moderate-to-severe TBI increases the risk of subsequent Alzheimer's disease (AD), the most common type of dementia. 2) Repetitive, often subconcussive, mild TBIs increases the risk for chronic traumatic encephalopathy (CTE), a degenerative neuropathology. 3) TBI may be a risk factor for other neurodegenerative disorders that can be associated with dementia. 4) TBI appears to lower the age of onset of TBI-related neurocognitive syndromes, potentially adding "TBI cognitive-behavioral features". The literature further indicates several specific risk factors for TBI-associated dementia: 5) any blast or blunt physical force to the head as long as there is violent head displacement; 6) decreased cognitive and/or neuronal reserve and the related variable of older age at TBI; and 7) the presence of apolipoprotein E ɛ4 alleles, a genetic risk factor for AD. Finally, there are neuropathological features relating TBI with neurocognitive syndromes: 8) acute TBI results in amyloid pathology and other neurodegenerative proteinopathies; 9) CTE shares features with neurodegenerative dementias; and 10) TBI results in white matter tract and neural network disruptions. Although further research is needed, these ten findings suggest that dose-dependent effects of violent head displacement in vulnerable brains predispose to dementia; among several potential mechanisms is the propagation of abnormal proteins along damaged white matter networks.

Multimodal MR Imaging Signatures of Cognitive Impairment in Active Professional Fighters

Purpose To investigate whether combining multiple magnetic resonance (MR) imaging modalities such as T1-weighted and diffusion-weighted MR imaging could reveal imaging biomarkers associated with cognition in active professional fighters. Materials and Methods Active professional fighters (n = 297; 24 women and 273 men) were recruited at one center. Sixty-two fighters (six women and 56 men) returned for a follow-up examination. Only men were included in the main analysis of the study. On the basis of computerized testing, fighters were separated into the cognitively impaired and nonimpaired groups on the basis of computerized testing. T1-weighted and diffusion-weighted imaging were performed, and volume and cortical thickness, along with diffusion-derived metrics of 20 major white matter tracts were extracted for every subject. A classifier was designed to identify imaging biomarkers related to cognitive impairment and was tested in the follow-up dataset. Results The classifier allowed identification of seven imaging biomarkers related to cognitive impairment in the cohort of active professional fighters. Areas under the curve of 0.76 and 0.69 were obtained at baseline and at follow-up, respectively, with the optimized classifier. The number of years of fighting had a significant (P = 8.8 × 10^-7) negative association with fractional anisotropy of the forceps major (effect size [d] = 0.34) and the inferior longitudinal fasciculus (P = .03; d = 0.17). A significant difference was observed between the impaired and nonimpaired groups in the association of fractional anisotropy in the forceps major with number of fights (P = .03, d = 0.38) and years of fighting (P = 6 × 10^-8, d = 0.63). Fractional anisotropy of the inferior longitudinal fasciculus was positively associated with psychomotor speed (P = .04, d = 0.16) in nonimpaired fighters but no association was observed in impaired fighters. Conclusion Without enforcement of any a priori assumptions on the MR imaging-derived measurements and with a multivariate approach, the study revealed a set of seven imaging biomarkers that were associated with cognition in active male professional fighters. ^© RSNA, 2017 Online supplemental material is available for this article.

Prevalence of Traumatic Findings on Routine MRI in a Large Cohort of Professional Fighters

BACKGROUND AND PURPOSE

Previous studies investigating MR imaging abnormalities among fighters have had small sample sizes. This investigation assessed a large number of fighters using the same conventional sequences on the same scanner.

MATERIALS AND METHODS

Conventional 3T MR imaging was used to assess 499 fighters (boxers, mixed martial artists, and martial artists) and 62 controls for nonspecific WM changes, cerebral microhemorrhage, cavum septum pellucidum, and cavum vergae. The lengths of the cavum septum pellucidum and cavum vergae and the ratio of cavum septum pellucidum to the septum pellucidum lengths were assessed.

RESULTS

The prevalence of nonspecific WM changes was similar between groups. Fighters had a prevalence of cerebral microhemorrhage (4.2% versus 0% for controls, P = .152). Fighters had a higher prevalence of cavum septum pellucidum versus controls (53.1% versus 17.7%, P < .001) and cavum vergae versus controls (14.4% versus 0%, P < .001). The lengths of the cavum septum pellucidum plus the cavum vergae (P < .001), cavum septum pellucidum (P = .025), and cavum septum pellucidum to the septum pellucidum length ratio (P = .009) were higher in fighters than in controls. The number of fights slightly correlated with cavum septum pellucidum plus cavum vergae length (R = 0.306, P < .001) and cavum septum pellucidum length (R = 0.278, P < .001). When fighters were subdivided into boxers, mixed martial artists, and martial artists, results were similar to those in the whole-group analysis.

CONCLUSIONS

This study assessed MR imaging findings in a large cohort demonstrating a significantly increased prevalence of cavum septum pellucidum among fighters. Although cerebral microhemorrhages were higher in fighters than in controls, this finding was not statistically significant, possibly partially due to underpowering of the study.

A prospective microstructure imaging study in mixed-martial artists using geometric measures and diffusion tensor imaging: methods and findings

Although diffusion magnetic resonance imaging (dMRI) has been widely used to characterize the effects of repetitive mild traumatic brain injury (rmTBI), to date no studies have investigated how novel geometric models of microstructure relate to more typical diffusion tensor imaging (DTI) sequences. Moreover, few studies have evaluated the sensitivity of different registration pipelines (non-linear, linear and tract-based spatial statistics) for detecting dMRI abnormalities in clinical populations. Results from single-subject analyses in healthy controls (HC) indicated a strong negative relationship between fractional anisotropy (FA) and orientation dispersion index (ODI) in both white and gray matter. Equally important, only moderate relationships existed between all other estimates of free/intracellular water volume fractions and more traditional DTI metrics (FA, mean, axial and radial diffusivity). These findings suggest that geometric measures provide differential information about the cellular microstructure relative to traditional DTI measures. Results also suggest greater sensitivity for non-linear registration pipelines that maximize the anatomical information available in T1-weighted images. Clinically, rmTBI resulted in a pattern of decreased FA and increased ODI, largely overlapping in space, in conjunction with increased intracellular and free water fractions, highlighting the potential role of edema following repeated head trauma. In summary, current results suggest that geometric models of diffusion can provide relatively unique information regarding potential mechanisms of pathology that contribute to long-term neurological damage.

Advanced magnetic resonance imaging and neuropsychological assessment for detecting brain injury in a prospective cohort of university amateur boxers

BACKGROUND/AIM

The safety of amateur and professional boxing is a contentious issue. We hypothesised that advanced magnetic resonance imaging and neuropsychological testing could provide evidence of acute and early brain injury in amateur boxers.

METHODS

We recruited 30 participants from a university amateur boxing club in a prospective cohort study. Magnetic resonance imaging (MRI) and neuropsychological testing was performed at three time points: prior to starting training; within 48 h following a first major competition to detect acute brain injury; and one year follow-up. A single MRI acquisition was made from control participants. Imaging analysis included cortical thickness measurements with Advanced Normalization Tools (ANTS) and FreeSurfer, voxel based morphometry (VBM), and Tract Based Spatial Statistics (TBSS). A computerized battery of neuropsychological tests was performed assessing attention, learning, memory and impulsivity.

RESULTS

During the study period, one boxer developed seizures controlled with medication while another developed a chronic subdural hematoma requiring neurosurgical drainage. A total of 10 boxers contributed data at to the longitudinal assessment protocol. Reasons for withdrawal were: logistics (10), stopping boxing (7), withdrawal of consent (2), and development of a chronic subdural hematoma (1). No significant changes were detected using VBM, TBSS, cortical thickness measured with FreeSurfer or ANTS, either cross-sectionally at baseline, or longitudinally. Neuropsychological assessment of boxers found attention/concentration improved over time while planning and problem solving ability latency decreased after a bout but recovered after one year.

CONCLUSION

While this neuroimaging and neuropsychological assessment protocol could not detect any evidence of brain injury, one boxer developed seizures and another developed a chronic sub-dural haematoma.

MR Imaging Applications in Mild Traumatic Brain Injury: An Imaging Update

Mild traumatic brain injury (mTBI), also commonly referred to as concussion, affects millions of Americans annually. Although computed tomography is the first-line imaging technique for all traumatic brain injury, it is incapable of providing long-term prognostic information in mTBI. In the past decade, the amount of research related to magnetic resonance (MR) imaging of mTBI has grown exponentially, partly due to development of novel analytical methods, which are applied to a variety of MR techniques. Here, evidence of subtle brain changes in mTBI as revealed by these techniques, which are not demonstrable by conventional imaging, will be reviewed. These changes can be considered in three main categories of brain structure, function, and metabolism. Macrostructural and microstructural changes have been revealed with three-dimensional MR imaging, susceptibility-weighted imaging, diffusion-weighted imaging, and higher order diffusion imaging. Functional abnormalities have been described with both task-mediated and resting-state blood oxygen level-dependent functional MR imaging. Metabolic changes suggesting neuronal injury have been demonstrated with MR spectroscopy. These findings improve understanding of the true impact of mTBI and its pathogenesis. Further investigation may eventually lead to improved diagnosis, prognosis, and management of this common and costly condition. (©) RSNA, 2016.

Injuries Sustained by the Mixed Martial Arts Athlete

Context:

Mixed martial arts (MMA) is rapidly growing in popularity in the United States and abroad. This combat sport joins athletes from a wide variety of martial art disciplines, each with characteristic and distinguishing injury profiles, together in competition. Because of increasing participation by professionals and amateurs alike, injuries sustained by MMA athletes have been on the rise.

Evidence Acquisition:

A review of relevant publications using the search term mixed martial arts and each of its component combat sports (eg, Muay Thai, Brazilian jiu-jitsu) from 1980 through 2015 was completed using PubMed and Google Scholar.

Study Design:

Clinical review.

Level of Evidence:

Level 5.

Results:

The majority of studies on MMA injuries evaluate those sustained during competition, which range in incidence from 22.9 to 28.6 per 100 fight-participations. Striking-predominant disciplines such as boxing, karate, and Muay Thai have high rates of head and facial injuries, whereas submission-predominant disciplines such as Brazilian jiu-jitsu, judo, and wrestling have high rates of joint injuries.

Conclusion:

Numerous studies have evaluated injuries in athletes who participate in MMA and its component disciplines during competition but much remains to be discovered about injuries sustained during training and in specific patient populations such as adolescents and women.

Novel Method of Weighting Cumulative Helmet Impacts Improves Correlation with Brain White Matter Changes After One Football Season of Sub-concussive Head Blows

One football season of sub-concussive head blows has been shown to be associated with subclinical white matter (WM) changes on diffusion tensor imaging (DTI). Prior research analyses of helmet-based impact metrics using mean and peak linear and rotational acceleration showed relatively weak correlations to these WM changes; however, these analyses failed to account for the emerging concept that neuronal vulnerability to successive hits is inversely related to the time between hits (TBH). To develop a novel method for quantifying the cumulative effects of sub-concussive head blows during a single season of collegiate football by weighting helmet-based impact measures for time between helmet impacts. We further aim to compare correlations to changes in DTI after one season of collegiate football using weighted cumulative helmet-based impact measures to correlations using non-weighted cumulative helmet-based impact measures and non-cumulative measures. We performed a secondary analysis of DTI and helmet impact data collected on ten Division III collegiate football players during the 2011 season. All subjects underwent diffusion MR imaging before the start of the football season and within 1 week of the end of the football season. Helmet impacts were recorded at each practice and game using helmet-mounted accelerometers, which computed five helmet-based impact measures for each hit: linear acceleration (LA), rotational acceleration (RA), Gadd Severity Index (GSI), Head Injury Criterion (HIC₁₅), and Head Impact Technology severity profile (HITsp). All helmet-based impact measures were analyzed using five methods of summary: peak and mean (non-cumulative measures), season sum-totals (cumulative unweighted measures), and season sum-totals weighted for time between hits (TBH), the interval of time from hit to post-season DTI assessment (TUA), and both TBH and TUA combined. Summarized helmet-based impact measures were correlated to statistically significant changes in fractional anisotropy (FA) using bivariate and multivariable correlation analyses. The resulting R ² values were averaged in each of the five summary method groups and compared using one-way ANOVA followed by Tukey post hoc tests for multiple comparisons. Total head hits for the season ranged from 431 to 1850. None of the athletes suffered a clinically evident concussion during the study period. The mean R ² value for the correlations using cumulative helmet-based impact measures weighted for both TUA and TBH combined (0.51 ± 0.03) was significantly greater than the mean R ² value for correlations using non-cumulative HIMs (vs. 0.19 ± 0.04, p < 0.0001), unweighted cumulative helmet-based impact measures (vs. 0.27 + 0.03, p < 0.0001), and cumulative helmet-based impact measures weighted for TBH alone (vs. 0.34 ± 0.02, p < 0.001). R ² values for weighted cumulative helmet-based impact measures ranged from 0.32 to 0.77, with 60% of correlations being statistically significant. Cumulative GSI weighted for TBH and TUA explained 77% of the variance in the percent of white matter voxels with statistically significant (PWMVSS) increase in FA from pre-season to post-season, while both cumulative GSI and cumulative HIC₁₅ weighted for TUA accounted for 75% of the variance in PWMVSS decrease in FA. A novel method for weighting cumulative helmet-based impact measures summed over the course of a football season resulted in a marked improvement in the correlation to brain WM changes observed after a single football season of sub-concussive head blows. Our results lend support to the emerging concept that sub-concussive head blows can result in sub-clinical brain injury, and this may be influenced by the time between hits. If confirmed in an independent data set, our novel method for quantifying the cumulative effects of sub-concussive head blows could be used to develop threshold-based countermeasures to prevent the accumulation of WM changes with multiple seasons of play.

Reduced white matter integrity in amateur boxers

INTRODUCTION

Professional boxing can lead to chronic traumatic encephalopathy, a variant of traumatic brain injury (TBI). Its occurrence in amateur boxers is a matter of debate since amateur boxing is considered to be less harmful due to more strict regulations. However, several studies using different methodological approaches have revealed subtle signs of TBI even in amateurs. Diffusion tensor imaging (DTI) is sensitive to microscopic white matter changes and has been proven useful in TBI when routine MR imaging often is unrevealing.

METHODS

DTI, with tract-based spatial statistics (TBSS) together with neuropsychological examination of executive functions and memory, was used to investigate a collective of 31 male amateur boxers and 31 age-matched controls as well as a subgroup of 19 individuals, respectively, who were additionally matched for intellectual performance (IQ).

RESULTS

All participants had normal findings in neurological examination and conventional MR. Amateur boxers did not show deficits in neuropsychological tests when their IQ was taken into account. Fractional anisotropy was significantly reduced, while diffusivity measures were increased along central white matter tracts in the boxers group. These changes were in part associated with the number of fights.

CONCLUSIONS

TBSS revealed widespread white matter disturbance partially related to the individual fighting history in amateur boxers. These findings closely resemble those in patients with accidental TBI and indicate similar histological changes in amateur boxers.