6th International Conference on Concussion in Sport: Amsterdam 2022

For over twenty years, the Concussion in Sport Group has convened to create five influential international statements regarding sports-related concussions. This document represents the culmination of the 6th International Conference on Concussion in Sport, held in Amsterdam from October 27-30, 2022. The conference methodology has evolved from past gatherings and was structured around expert panel discussions, workshops, and the revision and development of new clinical assessment tools.

In addition to this consensus statement, the conference produced several revised resources, including the 6th edition of the Concussion Recognition Tool (CRT6) and the Sports Concussion Assessment Tool (SCAT6, along with a version tailored to children, Child SCAT6). Furthermore, a brand-new resource, the Sports Concussion Office Assessment Tool-6 (SCOAT6, along with a child-focused version, Child SCOAT6), was unveiled.

The latest conference also incorporated fresh elements to our understanding of concussion, with particular emphasis on para athletes, insights from the athletes themselves, concussion-specific ethical considerations in medical practice, issues regarding athletes' retirement, and potential long-term impacts of sports-related concussions, including the prospect of neurodegenerative disease.

This statement encapsulates the latest knowledge on preventing, assessing, and managing concussions, drawing from a rich body of evidence. It also highlights areas where further research is needed to continue advancing our understanding and treatment of concussions.

In earlier consensus statements, such as the one from Berlin, concussion-related information was organized into what is referred to as the "11 R's". This structure facilitates a seamless flow of information concerning the clinical assessment and management of concussive injuries. In this article, we will adopt a similar approach, highlighting significant points from each subgroup. We'll specifically focus on the updates and innovations from the latest Amsterdam consensus statement, exploring fresh insights and progress in the sports related concussion field.

RECOGNISE: DEFINITION OF SPORT-RELATED CONCUSSION

In anticipation of the Amsterdam International Consensus Conference on Concussion in Sport, the Scientific Committee acknowledged a necessary adjustment to the Berlin definition of sport-related concussion (SRC). This modification mirrors our evolved comprehension of SRC's pathophysiology. The reimagined definition, endorsed by the majority, encapsulates SRC in this way:

“Sport-related concussion is a traumatic brain injury caused by a direct blow to the head, neck or body resulting in an impulsive force being transmitted to the brain that occurs in sports and exercise-related activities. This initiates a neurotransmitter and metabolic cascade, with possible axonal injury, blood flow change ,and inflammation affecting the brain. Symptoms and signs may present immediately, or evolve over minutes or hours, and commonly resolve within days, but may be prolonged. No abnormality is seen on standard structural neuroimaging studies (computed tomography or magnetic resonance imaging T1- and T2-weighted images), but in the research setting, abnormalities may be present on functional, blood flow or metabolic imaging studies. Sport-related concussion results in a range of clinical symptoms and signs that may or may not involve loss of consciousness. The clinical symptoms and signs of concussion cannot be explained solely by (but may occur concomitantly with) drug, alcohol, or medication use, other injuries (such as cervical injuries, peripheral vestibular dysfunction) or other comorbidities (such as psychological factors or coexisting medical conditions).”

Recently, the Mild TBI Task Force of the American Congress of Rehabilitation Medicine (ACRM) has established a new set of diagnostic criteria for mild traumatic brain injury (MTBI). (1) Their work, rooted in quick, comprehensive evidence reviews and collective expert consensus, introduces criteria that can be applied diversely, from athletic contexts to civilian and military trauma situations.

The ACRM diagnosis of mild TBI is as followed A diagnosis of mild traumatic brain injury (MTBI) is established when, after a biomechanically plausible injury, the meets at least one of the following three criteria The presence of one or more clinical signs attributable to brain injury.

The existence of at least two acute symptoms and a minimum of one clinical or laboratory finding, all indicative of brain injury.The detection of clear evidence of TBI through neuroimaging, such as trauma-related intracranial abnormalities visible on computed tomography or structural magnetic resonance imaging.

Reduce: Prevention of concussion

Emphasizing a proactive approach towards concussion prevention can significantly lower the rates of injuries, chances of recurrent injuries, and the risk of persistent symptoms. It is critical that all stakeholders, including policymakers in sports and healthcare providers, diligently work towards identifying and refining strategies tailored to prevent sport-related concussions (SRC) within their unique environments. By putting the prevention of SRC at the forefront across all levels of sports, we can achieve a substantial positive impact on public health.

Research focusing on the efficacy of SRC prevention strategies has seen a massive surge in recent years, with an almost threefold increase over the past five years. These studies have scrutinized a variety of preventive measures, encompassing policy and rule alterations, personal protective equipment, training methods, and management procedures. It's noteworthy that over 60% of this research specifically targeted children and adolescents. (2)In light of the consensus statement, we've seen intriguing updates regarding potential prevention strategies.

A study conducted by Eliason P et al, 2022, shed light on an intriguing 28% reduction in concussion injuries across all age groups when mouthguards were utilized by child and adolescent hockey players.(2) Alterations to the rules of the game can serve as an initial safeguard for curbing concussion injuries. This is a facet of what is known as primary prevention. One such promising strategy is the prohibition of body checking in ice hockey for children and adults. As per the findings of Eliason P et al, 2022, this strategy led to a significant 58% decrease in ice hockey-related concussion injuries.(2) Consequently, the prevailing consensus advocates the disallowance of body checking in all children's hockey games and in most adolescent levels (2-6).

The consensus also endorses strategies that curtail contact practices in American football. According to Eliason P et al, 2022, policies and rules that limited the frequency, intensity, and duration of contact practices resulted in a significant 64% reduction in practice-related concussions (2).

An intriguing finding is the impact of Neuromuscular Training (NMT) warm-ups on reducing concussion injuries in rugby players across all age groups (7). A significant reduction in concussion rates was observed even with the implementation of this program as few as three times per week. While this method requires further validation through extensive research, the current consensus recommends the inclusion of an NMT warm-up as part of a comprehensive approach to mitigate the incidence of concussions.

REMOVE: SIDELINE EVALUATION

The most prudent course of action when a sport-related concussion is suspected is to immediately remove the player from the game. This decision is typically based on the manner of injury and the presence of acute signs and symptoms that prompt a medical professional to further evaluate the player before allowing a return to play. Certain signs and symptoms are particularly alarming, including an actual or suspected loss of consciousness, seizures, rigid body posturing, lack of coordination, poor balance, confusion, behavioral changes, and amnesia. (8,9)

For athletes aged 12 and older, Maddock's questions remain an effective on-field screening tool for possible concussions, particularly in cases where the injury may not be readily apparent. The Sport Concussion Assessment Tool (SCAT) is a reliable method used in conjunction with a multi-modal approach to distinguish between concussed and non-concussed athletes. It has been shown to be reliable within the first 72 hours post-injury and even up to a week following the injury.(9,10)

The Newly Formed SCAT6/ Child SCAT6 Based on information on the findings of systematic review and expert panel discussions the following recommendations were made to the SCAT5 to be included in the newly formed SCAT6. Improve psychometric properties: longer word list (eg, 12- or 15-word list) and remove the 5-word list. This is due to the ceiling effect that was observed on the 5 list learning and concentration subtest.(8) Further examine form differences on existing 10-word lists and consider the use of regression-based norms.

Create a cognitive composite score to improve the test–retest reliability and reduce false positives. Add digits (ie, increase the longest string by two digits) to the digit span backward subtest to reduce ceiling effects. Revise months backward to include a component of timed information processing. Add timed dual gait tasks.

Implement tests and/or procedures to assess the performance validity of baseline testing. Add a more robust set of visible signs to the SCAT6/Child SCAT6/CRT6, including: Falling with no protective action, tonic posturing, impact seizure, ataxia/motor incoordination, altered mental status and blank/vacant/dazed look.

Support serial SCAT6/Child SCAT6 assessments after an athlete is removed from play, for example, half-time after the game and 24–48 hours after injury. The consensus meeting also established that the newly introduced Child SCAT6 is best suited for children aged between 8-12 years old. Further, the panel stressed the importance of a comprehensive and unhurried screening process. To execute a multimodal screen effectively, at least 10-15 minutes should be allocated. Consequently, the consensus advised that sports with time constraints that could limit this necessary process should amend their rules to accommodate the proper detection and screening of sport-related concussions.

Re-Evaluate: The Office Assessment

The primary aim of an in-office evaluation following a sports-related concussion is twofold: firstly, to promptly identify any warning signs that could indicate a life-threatening condition, and secondly, to establish an appropriate treatment trajectory for managing the concussion. The Sports Concussion Office Assessment Tool (SCOAT6, or Child SCOAT6 for younger patients) equips healthcare professionals with a systematic approach for investigating the multifaceted clinical implications of a concussion. This instrument not only facilitates the detection of specific areas that require therapeutic intervention, but also aids in identifying when a specialist referral is warranted and in monitoring the patient's recovery progress (11). Thus, the SCOAT6/Child SCOAT6 serves as a standardized guideline for conducting comprehensive concussion assessments during the subacute phase, from 72 hours up to several weeks after the injury.

The clinical framework of the SCOAT6/ Child SCOAT6 include

(**=Special recommendations on the Child SCOAT6)

Symptom Scale (Mirroring the SCAT6)
Word recall and digit backwards test (10 word recall and digital call back is advised, if the athlete has a “ceiling effect” with 10 a 15 word list may be used)
Measurement of systolic and diastolic blood pressure and heart rate from both the supine and standing position
Evaluation of the cervical spine (Range of motion, muscle palpation and midline/ segmental tenderness)
Neurological exam (Cranial nerve and spinal nerve assessment, motor function, sensation and deep tendon reflexes)
Timed tandem gait (Both as a single task and then will conjunction with cognitive task)
Modified Vestibular-Ocular Motor Screen Delayed word recall (Minimum of 5 minutes after completion)**
Additional symptoms for parent and child reporting**
Age appropriate cognitive reaction time, (Recommended the Symbol Digit Modalities Test)**
Validated pediatric measure ( Orthostatic tachycardia, orthostatic intolerance, vestibular and oculomotor function and child mental health and sleep questionnaires.)

Rest and Exercise

Exercise has long been recognized as a potent tool in managing mild traumatic brain injuries, often becoming the cornerstone of concussion rehabilitation due to its significant influence on blood flow regulation and dysautonomia. Recent research breakthroughs have underscored the therapeutic effects of introducing physical activity early in the treatment regimen. This strategy can greatly expedite recovery time and may help ward off post-concussion syndrome.

Contrary to the long-held belief that rest was the optimal response to a concussion, we now understand, thanks largely to the work of Dr. Leddy and the University of Buffalo, that physical exercise plays a crucial role in recovery. However, the ideal timeframe for introducing early physical activity and sub-symptom threshold exercise has always been a subject of debate.

In the latest consensus, the panel advocates for early physical activity, where tolerated, within 24-48 hours following a concussion injury. Suggested activities include walking or using a stationary bike. This recommendation is based on a 2023 study by Leddy et al., which found that early-stage exercise and physical activity shortened the recovery period by an average of 4.64 days.(12)Furthermore, the consensus statement includes a vital update on when to introduce exercise testing: sub-symptom threshold exercise should be incorporated between 2 and 10 days post-concussion.(12)

This significant update further emphasizes the benefits of early exercise intervention in promoting recovery and reducing the incidence of post-concussion syndrome. The panel also updated the recommendation on screen time following an acute concussion. The consensus recommends limiting screen time within the first 48 hours of a concussion injury. This guidance has been shown to have a positive effect on recovery in the initial stages. The consensus has also highlighted the detrimental impact of sleep disturbances on the risk of developing persistent symptoms.

Refer

Referrals frequently play a pivotal role in the management of post-concussion syndrome, given the myriad of factors involved in comprehensive concussion care. The consensus statement uses the term "persisting symptoms" to describe symptoms that continue for more than four weeks in children, adolescents, and adults.

In the case of an athlete with persistent symptoms the need for referral to a specialized health care professional may be the appropriate next step of care. When determining the need for referral, having a standardized symptoms list and diagnostic criteria can help health care professionals communicate between expertise.

This year's emphasis on a multimodal approach and leveraging standardized symptom rating scales for a thorough standardized evaluation. The consensus also provides an example; the SCOAT6/Child SCOAT6 as an effective tool in identifying specific symptoms that may necessitate referral for specialized care.

Rehabilitation

The recent consensus emphasizes the integral part both the cervical spine and the vestibular system play in the persistence of symptoms, pointing towards a significant interconnection between these two systems.

If dizziness, neck discomfort, or headaches continue beyond a ten-day period, the consensus suggests incorporating cervico-vestibular rehabilitation into the patient's therapeutic regimen.(13) In cases where individuals, irrespective of age, experience dizziness or balance issues, the consensus proposes the use of either vestibular or cervico-vestibular rehabilitation. This recommendation sheds light on the pivotal role of the cervical spine in managing vestibular symptoms.

Moreover, the consensus statement encourages consideration of the concurrent use of subsymptom threshold exercise with other treatments. The goal of this integrated approach is to offer a more encompassing and effective therapy.

Recovery

The concept of "clinical recovery" from a concussion varies among researchers and health care professionals, making the definition of complete recovery somewhat elusive. Nonetheless, the latest consensus provides clarity by outlining three critical elements to evaluate comprehensive recovery. These aspects should also be prioritized in future research to better understand the process of concussion recovery.

Assessment of symptoms at rest, during cognitive activities, and after physical exertion.Evaluation of the progress in outcomes related to persistent symptoms. For instance, physical exertion, balance tests, VOMS (Vestibular/Ocular Motor Screening), and cognitive tasks.Measures for successful return to learning and sporting activities.

The potential utility of biomarkers in the detection of concussions is an emerging field, with a particular focus on their role in establishing the physiological recovery of an athlete. Current research indicates promising results; however, their clinical application remains presently discouraged. Going forward, more extensive investigations are required to ascertain the role of biomarkers and other diagnostic technologies in facilitating a more accurate determination of physiological recovery following a concussion.

Return To Learn/ Return To Sport

Return To LearnThe systematic reintegration of athletes into their academic environment can have a significant positive impact on their recovery process. In fact, findings from a systematic review have highlighted an extended recovery duration in instances where athletes experienced delayed access to medical professionals, emphasizing the critical role of proper and timely healthcare in managing athletes' return to learning and social activities (14).

It is essential, however, to note that complete rest in the immediate 24-48 hours post-injury is not the ideal approach. The current consensus recommends a period of 'relative rest', characterized by a period of activities of daily living and reduced screen time. As athletes progress through these stages of return to learning, a mild exacerbation of symptoms is deemed acceptable. Mild exacerbation is characterized as no more than a 2 point increase in symptoms on a 10 point scale. This informed and methodical approach ensures a smoother and more effective transition back to their regular academic and social routines.

Return To Sport The Amsterdam consensus statement provides the framework for an athlete's return to sporting events, building upon the guidelines set out in the Berlin consensus. One key update pertains to the aerobic exercise stage, originally labeled as Step 2 in the Berlin consensus. The Amsterdam consensus further delineates this stage into two subcategories: 2A (Light) and 2B (Moderate), each with the aim of increasing the athlete's heart rate in a controlled manner.

Light aerobic exercise, defined as stationary cycling or light resistance training, should be performed at or below 55% of the athlete's maximum heart rate. On the other hand, moderate aerobic exercise should target approximately 70% of their maximum heart rate.

Moreover, an additional clearance step has been incorporated before the initiation of non-contact training drills. This clearance step mandates the resolution of all concussion-related symptoms, cognitive function abnormalities, and other clinical findings, even under or after physical exertion. Only upon this clearance can stages 4-6 commence, ensuring a safer and more effective return-to-play journey for the athlete.

Reconsider: Potential Long-Term Effects

There is widespread concern among athletes about the potential long-term effects on brain health due to prior concussion injuries. This is particularly relevant when contemplating the residual effects of a single concussion or multiple such incidents. The Amsterdam consensus assessed available published studies that employed research designs capable of estimating future risk for athletes reporting head trauma, including both prospective and retrospective studies with exposed and unexposed cohorts.

Upon reviewing the literature, the Amsterdam consensus concluded that athletes, overall, do not have an increased risk of depression, suicidality, psychiatric hospitalization, death due to psychiatric disorders, or death by suicide, compared to the general population (15-24). It was also established that former male amateur athletes do not face a higher risk of cognitive impairment, neurological disorders, or neurodegenerative diseases when compared to the general populace.

However, some studies have reported higher mortality rates from neurological diseases and dementia in former professional American football players, as well as a higher mortality rate from ALS in former soccer and American football players.(25-26) Nevertheless, it is crucial to note the difficulties in attributing these findings directly to sports-related trauma. The existing studies face limitations due to their inability to thoroughly examine and adjust for numerous factors that may contribute to the increased mortality rate associated with neurological diseases.

Chronic Traumatic Encephalopathy (CTE) is currently identified as a neuropathological entity. The term CTE neuropathologic change (CTE-NC) is utilized to denote the post-mortem neuropathological manifestation of CTE, distinguishing it from potential clinical conditions.(27-29)However, the consensus has indicated that the prevalence of CTE-NC among athletes, military veterans, and individuals from the general public remains unclear. Additionally, whether CTE-NC directly causes psychiatric or neurological issues is also unknown. Current literature also emphasizes that any association between CTE-NC and Alzheimer's disease or the inevitable progression of CTE-NC is still undetermined.

Retire

The Amsterdam consensus has more of a detailed recommendation on retirement decisions in sport. Decisions to retire or quit contact or collision sports due to traumatic brain injuries are complex and multifaceted, and there's no clear-cut evidence highlighting specific factors that would definitely lead to retirement. Even though some sports have particular medical regulations for participation (like in boxing where a retinal detachment can disqualify you), these decisions shouldn't be taken lightly.

It's crucial to have a comprehensive evaluation by medical professionals well-versed in traumatic brain injuries and sports. This process should also include a multidisciplinary team, so that everything from patient-specific details to sports-specific nuances, and even socio-cultural factors are considered. The conversation with athletes should be balanced, providing them with the scientific evidence and uncertainties about their situation, as well as the benefits of participating in the sport. Importantly, athletes' preferences, risk tolerance, and mental readiness for decision-making should also be considered.

These discussions need to be carefully documented using language the individual understands, to avoid any misunderstandings. For younger athletes, parents or guardians should be involved too. It's also crucial that healthcare professionals (HCPs) make it clear about their role in the athlete’s care and any potential conflicts of interest.

This approach also applies to anyone involved in coaching or managing the athlete. For child or adolescent athletes, special care should be taken to ensure a smooth return to school and maintenance of healthy physical activity levels. This often needs a team effort involving parents, healthcare providers, school staff, and of course, the young athlete.

Lastly, it's important to remember the positive impacts of exercise on health. So, even if an athlete decides to retire from contact or collision sports, they should be encouraged to keep up with non-contact or low-contact physical activities. We want to ensure they continue to reap the benefits of exercise, even post-retirement.(88)

Para Sport

The trend of people with disabilities taking part in sports is steadily on the rise, and this group, comprising about 15% to 25% of the global population, is embracing everything from Paralympic events to mainstream sporting environments. Disabilities cover a wide range and include physical disability, intellectual disability, developmental disability, and hearing impairment. This opens up opportunities for participation in various sports, including popular ones like ice hockey and soccer, and specialized para-athlete sports like wheelchair racing and para swimming.

However, when a para athlete suffers a concussion, it presents a unique challenge due to the interaction between the individual’s primary disability and the concussion's pathophysiology. Furthermore, the tools typically used to assess Sports-related Concussions (SRC), such as SCAT, don't necessarily work for the para athlete population, requiring a more personalized approach. Moreover, the literature is sparse on the subject of SRC in people with disabilities, but it's worth noting that elite Paralympic athletes seem to face a higher injury risk compared to their non-disabled counterparts.

Athletes with visual impairment may be at an even higher risk due to the likelihood of collisions or direct head contact. The characteristics of the individual’s underlying impairment can potentially affect everything from prevention methods and initial symptom detection to diagnosis, recovery, and treatment strategies.

The current Amsterdam concursus recommendations include baseline testing, given the variable nature of disability and potential for atypical concussion symptoms. For those with a history of central nervous system injury, like cerebral palsy or stroke, a longer initial rest period might be needed. Also, modifications in testing for symptoms through recovery, like using arm ergometry instead of a treadmill, and tailored return-to-sport protocols that consider the individual’s personal adaptive equipment, are advised. There's an urgent need for more research to improve our understanding of concussion assessment and management in para sport participants, including looking at modifiable risk factors, prevention strategies, reference data for assessment tools, and the unique challenges faced by under-researched subpopulations such as female and child/adolescent athletes with a disability. (31,32)

Bottom Line

The Amsterdam 2022 International Consensus Statement stands as a comprehensive review of the current literature available at the time of the consensus, expert panel consultations, and workshops. It aims to provide a thorough synthesis of the evidence and best practice guidelines for detecting, assessing, and managing sports-related concussions. This year's consensus has brought significant insights into all facets of concussion care, introducing a number of pivotal updates:

A refined definition of "concussion"
Recommendations for rule modifications and warm-up routines to mitigate the risk of concussion injuries
The introduction of the SCAT6 and SCOAT6/Child SCOAT6 tools
Revised strategies for return-to-learn and return-to-sport processes
The endorsement of early initiation of aerobic exercise as part of the recovery process
The inclusion of cervicovestibular rehabilitation for athletes experiencing neck pain, headaches, dizziness, and/or balance issues

Continual review of emerging research and evolution of procedures is paramount for progressive advancement in concussion care. To ensure athletes receive the optimal care, it's essential to stay informed of current recommendations to enhance clinical decision-making and practices.

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