Mild traumatic brain injury is sometimes referred to as an ‘invisible injury’ as there is often no objective evidence to help diagnose the damage done. Instead a diagnosis is made based on a host of subjective complaints.  Repetitive concussive and sub-concussive blows are linked to CTE.  This disease also cannot be diagnosed with certainty in living individuals and objective criteria demonstrating risk of this disease are lacking.

An interesting study was published in JAMA Neurology this month, however, showing promise that certain biomarkers may be “an objective tool to assess the degree of central nervous system injury in individuals with PCS (post concussion syndrome)” and further that this tool may even be used to screen athletes that are at high risk of developing CTE.

In the study, titled “Neurochemical Aftermath of Repetitive Mild Traumatic Brain Injury” the authors reviewed 16 athletes with a history of Post Concussion Syndrome (approximately half of which recovered within a year and the others having persistent symptoms beyond a year) along with a control group.  Neurofilament light proteins were significantly increased in players with PCS for more than 1 year and players with PCS had significantly lower cerebrospinal fluid amyloid-β levels compared with control individuals.

The authors concluded that these biomarkers could potentially be used to help screen athletes showing signs of too much damage which could, in turn, help athletes make a more informed retirement decision from combative and other contact sports.

Here is the study’s full abstract:

Importance  Evidence is accumulating that repeated mild traumatic brain injury (mTBI) incidents can lead to persistent, long-term debilitating symptoms and in some cases a progressive neurodegenerative condition referred to as chronic traumatic encephalopathy. However, to our knowledge, there are no objective tools to examine to which degree persistent symptoms after mTBI are caused by neuronal injury.

Objective  To determine whether persistent symptoms after mTBI are associated with brain injury as evaluated by cerebrospinal fluid biochemical markers for axonal damage and other aspects of central nervous system injury.

Design, Settings, and Participants  A multicenter cross-sectional study involving professional Swedish ice hockey players who have had repeated mTBI, had postconcussion symptoms for more than 3 months, and fulfilled the criteria for postconcussion syndrome (PCS) according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) matched with neurologically healthy control individuals. The participants were enrolled between January 2014 and February 2016. The players were also assessed with Rivermead Post Concussion Symptoms Questionnaire and magnetic resonance imaging.

Main Outcomes and Measures  Neurofilament light protein, total tau, glial fibrillary acidic protein, amyloid β, phosphorylated tau, and neurogranin concentrations in cerebrospinal fluid.

Results  A total of 31 participants (16 men with PCS; median age, 31 years; range, 22-53 years; and 15 control individuals [11 men and 4 women]; median age, 25 years; range, 21-35 years) were assessed. Of 16 players with PCS, 9 had PCS symptoms for more than 1 year, while the remaining 7 returned to play within a year. Neurofilament light proteins were significantly increased in players with PCS for more than 1 year (median, 410 pg/mL; range, 230-1440 pg/mL) compared with players whose PCS resolved within 1 year (median, 210 pg/mL; range, 140-460 pg/mL) as well as control individuals (median 238 pg/mL, range 128-526 pg/mL; P = .04 and P = .02, respectively). Furthermore, neurofilament light protein concentrations correlated with Rivermead Post Concussion Symptoms Questionnaire scores and lifetime concussion events (ρ = 0.58, P = .02 and ρ = 0.52, P = .04, respectively). Overall, players with PCS had significantly lower cerebrospinal fluid amyloid-β levels compared with control individuals (median, 1094 pg/mL; range, 845-1305 pg/mL; P = .05).

Conclusions and Relevance  Increased cerebrospinal fluid neurofilament light proteins and reduced amyloid β were observed in patients with PCS, suggestive of axonal white matter injury and amyloid deposition. Measurement of these biomarkers may be an objective tool to assess the degree of central nervous system injury in individuals with PCS and to distinguish individuals who are at risk of developing chronic traumatic encephalopathy.

In the last decade there has been great progress in public understanding that concussions are a form of traumatic brain injury, not simply ‘getting your bell rung’.

Current studies are showing, however, that sub-concussive blows over a prolonged period are equally troubling and a recent article published in the Journal of Neurosurgery Clinics of North America highlights this.

In short the authors of the article, titled “Repetitive Head Impacts and Chronic Traumatic Encephalopathy” note current literature indicates that “the number of years of exposure to contact sports, not the number of concussions, is significantly associated with more severe tau pathology in CTE, suggesting that repetitive head trauma, including sub-concussive injury, is the primary stimulus for the disease” a message that should resonate to all who choose to pursue either amateur or professional combative sports.

The full article can be purchased here.

One topic I often revisit is the reality that gloves in combative sports such as boxing, kickboxing and MMA do a great job protecting from superficial injury but likely lead to an increase of traumatic brain injury and CTE.

This week I had the pleasure of picking up a hard copy of Jason Thalken’s “Fight Like a Physicist“ who after experimentation published the following sober comments that regulators should consider next time they revisit sanctioning a gloveless combat sports event –

“Boxing gloves and MMA gloves are effective at absorbing and dispersing the energy of impact, which causes local tissue damage, but we have no reason to believe any gloves reduce momentum transfer.  In fact, thanks to the excellent hand protection gloves provide, fighters are able to punch with greater momentum than they would with bare knuckles, and they are able to attack hard targets like the head more often.  This means gloves do a great job of reducing the types of injuries associated with structural tissue damage (cuts, bruises, swelling, black eyes, and broken bones), but they also lead to an increase in the frequency and intensity of momentum transfer to the brain, which is directly related to diffuse axonal injury and CTE.

Fifty years ago, before we had a firm understanding of CTE, the choice was clear; use padded gloves to prevent injury.  Today we need to think a little harder.  A cut, a broken hand or an eye injury might stop a fight or even end a fighter’s career, but brain injury can take away a fighter’s ability to function as a human being, both in and out of the ring”

Adding to this site’s archives of combat sports safety studies, The Journal of Sports Health published a data review concluding that MMA combatants suffer an in competition injury rate between 22.9 and 28.6%.

In the recent study the authors reviewed 35 years of publications detailing injury rates in MMA or thier component sports.  The data revealed that “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.”

The study is titled “Injuries Sustained by the Mixed Martial Arts Athlete” and the full article can be purchased here.

In my latest review of safety studies in the world of combative sports, a recent article was published in the British Journal of Sports Medicine finding concussion ‘preventing’ sports equipment has ‘no effect’.
In the recent study, titled “Current State of Concussion Prevention Strategies: a systemic review and meta-analysis of prospective, controlled studies” the authors evaluated 14 studies reviewing the effects of “novel protective equipment“.  They concluded that while some equipment was effective in reducing “superficial head injury” (think cuts and bruises) when it came to concussion prevention the equipment “showed no effect of intervention“.

The study’s full abstract is reproduced below:

Abstract

Adding to this site’s archived summaries of studies addressing safety issues in combat sports, a recent study was published in the Journal of Neuroradiology canvassing the extent of objective white matter disturbance in the brains of amateur boxers compared to a control group.

The study, titled Reduced White Matter Integrity in Amateur Boxers, posed the question of whether amateur boxers would have white matter disturbance detectable on imaging given the greater safety protocols in place at the amateur level.  The study conducted  diffusion tensor imaging of the brains of 31 amateur boxers an compared these to a non boxing peer group.

The study found that “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.”

The full abstract is reproduced below –

It is becoming ever clearer that mileage matters when it comes to exposure of head trauma and poor long term cognitive outcomes.

A recent study, titled  “Cognitive, Psychiatric, And Neuropathological Manifestations Of Repetitive Mild Traumatic Brain Injury” published as a dissertationn paper in Wayne State University’s Psychiatry and Behavioral Neurosciences sought answers to the important question of how much traumatic ‘mileage’ is too much when it comes to brain functioning.

In the study, which can be found here, the authors administered  30 head impacts over an extended period of time to lightly anesthetized, completely unrestrained mice in order to mimic sports related concussive and sub concussive impacts.  The authors then “assessed the sensorimotor, psychiatric, and cognitive outcomes of rmTBI at two different time points using different impact conditions“.

The study concluded that “Animals receiving repeated head impacts exhibited outcomes consistent with those observed in athletes with a history of rmTBI including depression-like behavior and cognitive impairment…Notably, these outcomes occurred in mice receiving head impacts that did not delay recovery of the righting reflex indicating that subconcussive impacts present just as serious risk of injury to the CNS as concussive blows. Aside from this outcome, these data indicate that there is a cumulative and dose-dependent effect of repetitive head impacts that exacerbate the neurobehavioral and neuropathological outcomes as seen in humans with a history of rmTBI.”

The full abstract reads as follows –

Abstract

Millions of athletes participate in contact sports that involve repeated head impacts (e.g., football, ice hockey, boxing), often from a very young age, and it is feared that subsequent impacts can synergize with previous ones so that their effects on the brain become magnified. Repetitive mild traumatic brain injury (rmTBI) has been linked to the development of chronic traumatic encephalopathy (CTE). The neurodegeneration accompanying CTE occurs over many years following repeated head impacts and is characterized by progressive brain atrophy, accumulation of hyper-phosphorylated tau and aggregates of TDP-43, myelinated axonopathy, neuroinflammation and degeneration of white matter tracts. The relationship between head impact parameters (force, number, frequency) and the manifestations of rmTBI is not well understood nor is the severity or frequency of head injury required to trigger CTE. An animal model of rmTBI (i.e., sports-related TBI) is urgently needed to minimize risk of TBI in athletes and the studies described herein confirm that our method bears the attributes necessary to fulfill this need. The studies included in this project validate a method of rmTBI that unequivocally simulates human sports-related head impact in both form and outcome. To our knowledge, this is the first study to administer 30 head impacts over an extended period of time to a lightly anesthetized, completely unrestrained mouse. We have assessed the sensorimotor, psychiatric, and cognitive outcomes of rmTBI at two different time points using different impact conditions. Animals receiving repeated head impacts exhibited outcomes consistent with those observed in athletes with a history of rmTBI including depression-like behavior and cognitive impairment. The neuropathological outcomes of rmTBI included reactive gliosis, axonal degeneration, elevated levels of Aβ (1-42), β-amyloid, p-tau, TDP-43, and significant thinning of several white matter tracts. Notably, these outcomes occurred in mice receiving head impacts that did not delay recovery of the righting reflex indicating that subconcussive impacts present just as serious risk of injury to the CNS as concussive blows. Aside from this outcome, these data indicate that there is a cumulative and dose-dependent effect of repetitive head impacts that exacerbate the neurobehavioral and neuropathological outcomes as seen in humans with a history of rmTBI. This model will enable future study of the most pressing issues associated with sports-related head impact including the relationship between the number and frequency of head impacts to the development of behavioral and CTE-like outcomes. Future studies elucidating the cellular manifestations of rmTBI and its behavioral correlates will aid in the development of potential therapeutics. Finally, these results demonstrate the ability of our method to expand our understanding of the neuropathological, psychiatric, and cognitive sequelae underlying this insidious injury.

In my ongoing efforts to document scientific studies addressing safety issues in combat sports, a recent article was published examining the facial injury rate among boxing, wrestling and martial arts competitors.

The article, titled “Adding Insult to Injury – A National Analysis of Combat Sports-Related Facial Injury” was published this month in the Annals of Otology, Rhinology and Laryngology.  

The authors reviewed the National Electronic Injury Surveillance System (NEISS) for facial injuries from wrestling, boxing, and martial arts leading to emergency room visits from 2008 to 2013.  Perhaps somewhat counter-intuitively, the study found that wrestling, a combative sport without striking, led to the highest rate of facial injury requiring ER visits with an injury rate of 120 injuries per 100 000 participants with boxing and martial arts competitors suffering facial injuries at a rate of less than half of wrestlers.

The full abstract reads as follows:

Abstract

In my ongoing efforts to document scientific studies addressing safety issues in combat sports, a useful article was published this month in the Korean Journal of Neurotrauma addressing sport related head injuries and return to sport protocols.

While the recent article titled A Review of Sport-Related Head Injuries, does not present any new data or findings, it is a well authored concise summary on the topic.

Of particular value for combat sports athletes, trainers and regulators are the comments on return to sport following concussion.

Given that CTE is linked to repeated concussive/sub-concussive blows, that concussion victims are 2-5.8 times more likely to experience a subsequent concussion and lastly that consequences from multiple concussions can be cumulative combat sports stakeholders should be well aware of if or when it is safe to return to sport following a concussive injury. The article provides the following sensible advice:

Athletes are not allowed to return to sports unless their symptoms have completely remitted. After full symptom resolution, they should return to sporting activities in a stepwise manner according to graduated return to play protocol (Table 2).12) Each step of the protocol requires 24 hours, and the process stops if there are any symptoms. Therefore, at least 1 week is required to return to sporting activities. In the final stage, the athlete undergoes a medical check-up before they are cleared to return to their sport. If any symptoms are observed, the athlete is ordered to rest and return to the previous stage of the protocol.