How the latest technological advances in diagnosing concussion could influence sports policyDr Ben Koh, Dr Alan Pearce
Sport needs to have a greater awareness, and prepare for the enhanced use, of developments in medical technology. Such technologies may assist all sports bodies in taking reasonable precautions both to mitigate the acute and chronic medical risks of concussion and, legally, to discharge their duty of care towards participants.
The authors recently explored1 the potential impact of an approval of a blood test for head injuries on the duty of care towards players. We also foreshadowed how the standard of care expected of sporting codes and clubs in the management of concussions in athletes will change with rapidly advancing technology.
This article explains some of the major advances in technology in diagnosing concussions that show promise. Each of these technologies target different stages in the life cycle of an athlete at risk: from pre-participation to post-injury. Specifically, we examine:
In the context of concussion in sports policy and management, the practical aim at all the stages of the life cycle mentioned above is to either to prevent irreversible brain damage (e.g. Chronic traumatic encephalopathy (CTE), a neurodegenerative disease) or a sudden life threatening brain injury (e.g. Second Impact Syndrome (SIS) where an athlete who suffers a second head injury very soon after the first develops brain swelling that causes the brain to squeeze out of the confinements of the rigid skull and kills the patient).
The idea of screening in the pre-participation stage is to exclude vulnerable athletes from playing. For example, screening for cardiac issues is now not uncommon, especially at the elite or professional level. Individuals with enlarged hearts (hypertrophic cardiomyopathy, HCM) are excluded from the sport on the basis that HCM is the leading cause of exercise-related cardiovascular death in young athletes.2 It is presently not practical nor cost-effective to conduct pre-participation screening for brain vulnerabilities but this may change with new technologies and our improved understanding of head injuries. At present, what can potentially be done is to screen and quarantine junior or amateur athletes with previous head injuries from joining the senior or professional squad but this is not universally adopted.3
Screening at the participation stage (e.g. during training or actual games) involves picking up high risk events when they occur even if concussions are not obvious. For example, if a high impact force to an athlete’s head can be detected during a game, even before concussive signs are obvious, it could help with on-field decision making to stop play and allow that player to be removed from the playing area for assessment. At present, concussive signs often need to be florid before time-out occurs.
After a concussion is detected and formally diagnosed, the policy and legal consideration and medical management then focuses on the degree of functional or structural disturbance in deciding return-to-play plans. Because concussion cannot be detected on current standard structural neuroimaging studies, 4 decisions on allowing players to return-to-play (and therefore exposure to further head injury risk and SIS) is currently dependent on clinical assessment. We discussed in our earlier article how the process of return-to-play may be highly subjective.
Assuming athletes are truthful in reporting resolution of symptoms, the clinical decision making in those athletes that report the presence of symptoms will need to consider if those symptoms are unrelated phenomena or premorbid conditions unrelated to the head injury, downstream non-pathological physiological adaptive effects of a concussion, or if indeed true representation of ongoing concussion pathophysiology. Advances in surveillance techniques, innovations in imaging technologies, improvement in the tests of brain physiology, and new biomarkers may all potentially help provide objectivity in this process. The following discussion will now address some of the main technologies in each category to show how it may help contribute to sport concussion management and what its limitations are.
In recent years, there has been an increase in head sensor technologies aimed at quantifying head impacts experienced by players during training and play. The sensors measure the amount of linear and rotational force and the three-dimensional direction of the force on the head. Besides the information recorded from each discrete head impact event, data is accumulated during the season, and across seasons, to provide an overall picture of all impacts experienced by the player during their career. The goal of these devices is to act as a ‘surveillance’ system, a sort of biological passport, by quantifying head impacts experienced by athletes as they occur and over time.
In the United States, the most common of these surveillance devices, first used on the field in 2003, is the Head Impact Telemetry System (HITSTM, Simbex/Riddell, USA) where sensors are embedded within the athlete’s helmet. The HITSTM system has six accelerometers embedded in the helmet that collects movement data and alerts the surveillance officer when any of the accelerometers detect a force greater than a pre-determined threshold. For non-helmeted sports, a wearable impact sensor has been developed. The best known of these is the X-Patch (X2 Biosystems, USA), which was first released in 2012. The X-Patch is a behind-the-ear sensor attached to the skin. The X-Patch contains three accelerometers and a gyroscope, which collects linear and rotational accelerations in three-dimensions.
Whilst these devices have been used widely, concerns have been raised about the reliability and validity of the impacts measured. For example, for helmet sensor systems, factors such as fit and padding type may affect sensor coupling to the human head, and as a result create measurement error. Similarly, sensors stuck to the skin are subject to measurement errors if: the adhesion is not optimal, mounted under a helmet (such as in Ice Hockey), the sensor is not mounted suitably (i.e. position and orientation) over the correct anatomical location behind the ear. In these cases, sensor movement on the skin can create artifacts or amplify measurement error.
Recently a custom-fitted mouth guard sensor (HitIQ, Australia) providing three-dimensional direction measures for linear and rotational acceleration forces has been developed to measure head impacts. Laboratory validation and field studies have so far shown promise in having less measurement error when compared to skin-mounted or helmet sensor systems.5
Once the technical issues of measurement accuracy and threshold levels are resolved, surveillance instruments show promise in providing objective data for clinical decision making for concussion. For example, a player time-out can be called during a game (even before concussion symptoms are evident) if a high impact force on the head is detected. Between games, players with data showing high cumulative head impact may also be selectively and pre-emptively screened for brain injuries even if not exhibiting neurological symptoms.
It was mentioned before that clinical neuroimaging has currently little utility in the diagnosis of sports concussion. Standard methods such as magnetic resonance imaging (MRI) and computed tomography (CT) scanning, whilst suitable for brain injuries that show bleeding, bruising or skill fracture, is ineffective in detecting concussion.
Unlike traditional MRI that measure only the structure of the brain and changes to that structure during an injury, new technologies of functional magnetic resonance imaging (fMRI) measure brain activity that occur in different regions of the brain by detecting the increase in blood flow to regions of increased neural activity. Research in this area is still ongoing but better understanding of brain functional recovery signals on fMRI and early information on abnormal brain functioning even with no structural changes noted on MRI will be useful in the future for concussion diagnosis in the acute setting and help in safe return-to-play clinical decision-making for a first head injury in the context of preventing SIS.6
Other advancement in neuro-imagining techniques used in neurodegenerative diseases have also been used to investigate chronic effects of repeated head trauma. For example, positron emission tomography (PET) is a molecular-level imaging technique that detects the signal from a radioactive tracer that is injected into the body. The tracer seeks out abnormal cellular changes in the brain by binding onto substances such as amyloid-β and tau proteins associated with neurodegenerative diseases such as Alzheimer’s disease. Research is currently exploring the significance, if any, of these same PET findings in chronic traumatic encephalopathy (CTE). Whilst CTE is pathognomonic of repetitive head trauma commonly observed in boxers and military personnel, the clinical characteristics of CTE are broad and overlap with many symptoms seen in the spectrum of neurodegenerative diseases unrelated to sports concussion. Moreover, PET tauopathy scans findings have not as yet been validated in suitably powered cohort studies to see if positive PET tauopathy scans correlate with autopsy findings of CTE.
Another neuroimaging technology currently only used in the research setting is the Diffuse Tensor Imaging (DTI). The DTI is a MRI technique used to detect changes to the microstructure (the “wire cables and circuitry”) of the white matter in the brain. Many developmental, aging and pathologic processes of the brain influence the microstructural composition and architecture, and such changes may also occur following a history of repeated head trauma playing contact sports.7 Studies have shown that the athletes who sustain concussion and the athletes who experience repetitive sub-concussive impacts show changes in this microstructure similarly.8 A sub-concussion is where there are no signs or symptoms.9 DTI is currently restricted to the research setting, thus limiting its accessibility and clinical use for athletes.
Brain physiology research is re-emerging as an area of interest with the development of new techniques. Historical studies using electroencephalography (EEG), which measures the electrical activity of the brain during cognitive tasks, were not capable of detecting small changes in the EEG tracing that occurs in concussions. However recent developments in EEG techniques, such as computerised quantitative EEG (qEEG) allows for the identification of subtle variations in the patterns in the EEG data that may be clinically useful in diagnosing of, and monitoring recovery from, concussion.
Despite limited studies to date, transcranial magnetic stimulation (TMS) is another modality that shows promise in the management of concussion. TMS is a non-invasive technique that uses magnetic fields to stimulate nerve cells, called evoked potentials, that are quantified either by EEG or electromyography (EMG, measuring neuromuscular electrical activity). TMS provides data on brain physiology dysfunction useful in diagnosis and monitoring of concussion recovery.10
Research have shown that even when clinical symptoms of concussion resolve and cognitive measures have returned to the baseline level, persistent changes on electrophysiology studies may occur.11,12 There is still debate on whether these persistent changes detected in highly sensitive instruments provide an objective measure of an ongoing neurological issue that has not fully recovered or if they are changes of no clinical consequence. The reason for the confusion is largely due to the varied timelines of individual recovery from concussion and the indirect nature of the techniques. The indirect measurement of concussion makes it difficult to determine what biological mechanisms contribute to the electrophysiological observations detected and thus prevent any inferences of causation to be made.
With the recent FDA approval of the first biomarker for mild traumatic brain injury (mTBI) and concussion, there is intense interest in the efficacy of biomarkers as indicators for concussion diagnoses. A number of protein biomarkers of injury to different cell types and structures within the brain can be detected in peripheral blood, but utility and detection have been limited. The recent FDA biomarkers for mTBI and concussion, the Banyon Brain Trauma Indicator (BBTI), was discussed in our earlier paper. The research to date suggests that there are still no reliable biomarkers to monitor recovery following a concussion injury, but this is an area of much interest.
An alternative to protein biomarkers in detecting concussion is the search for micro-ribonucleic acids (miRNAs) that control gene expression. Studies on miRNAs in various neurological conditions including Alzheimer’s and Parkinson’s diseases, epilepsy and stroke suggests that it may potentially be useful in assessing recovery post-concussions.13 Whilst the use of a patient’s saliva to detect miRNA levels is possible, it suffers from reliability measures when compared to the test from blood samples.14
This article has sought to highlight the various research areas in which technologies used to detect and manage concussion that are occurring. Whilst these technological advances are currently still in development, their eventual and inevitable incorporation into sports policy and in medical management will no doubt influence not just the clinical care of athletes but potentially also the standard of care required of clubs and sporting codes. The ability to empirically and objectively detect and grade concussion will also result in rapid decisions made during a game, as well as return-to-play decision between games to be more closely scrutinised in liability cases. Any assessment based on the balance of probability standard would correspondingly be less influenced by subjective evidence of witnesses.
Sports policy, law and ethics have often fail to keep up with advances in technology. A recent example is the use of goal-line technology (GLT) where its adoption in football has been slow and protracted despite the availability of the technology for real world application for many years.15 Serious discussions into the amendment of any sports rules; management of technology reliability issues; the influence of the technology on the nature and culture of the sport; the cost impact from a global perspective (which include at the grassroots level); and any ethical issues that may arise from any potential new technology need to done by sporting codes beforehand as part of good risk governance.
Whilst the glacial speed of implementation of GLT may be warranted from an administrative perspective out of an abundance of caution, the same cannot be said of technologies relating to concussion that affect athletes’ health. The football codes (American football, Rugby Union and League, Australian Rules Football) to date have all been slow in managing the foreseeable risk of concussion that we now see play out in the courts. Will they start planning for a future of concussion technology in their sport now or will they continue to drop the ball until forced to change by legislatures and courts?
The authors would like to thank Professor Mark James for reviewing the paper and providing input.
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- Tags: Athlete Welfare | Banyan Brain Trauma Indicator (BBTI) | Chronic Traumatic Encephalopathy (CTE) | Concussion | National Football League (NFL) | Traumatic Brain Injuries (TBI) | United Kingdom (UK) | United States of America (USA)
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About the Author
Dr Ben Koh is a medical doctor with a Masters in Sports Medicine and a Masters in Psychology and has clinical and educational training in surgery, sports medicine, emergency medicine and critical care.
Dr Alan Pearce is an Associate Professor in the School of Allied Health at La Trobe University and a Senior Research Fellow in the Melbourne School of Health Sciences, The University of Melbourne.