Research Review By Dr. Jeff Cubos©

Date Posted:

October 2009

Study Title:

Consensus Statement on Concussion in Sport: The 3rd International Conference on Concussion in Sport Held in Zurich, November 2008


McCrory P, Meeuwisse W, Johnston K et al.

Author's Affiliations:

University of Melbourne, University of Calgary, Toronto Rehabilitation Institute

Publication Information:

Journal of Athletic Training 2009; 44(4): 434-448.

Also published in the Clinical Journal of Sport Medicine, Journal of Clinical Neuroscience, Journal of Clinical Sport Medicine, Journal of Science & medicine in Sport, Neurosurgery, Physical Medicine & Rehabilitation, and Scandinavian Journal of Science & Medicine in Sport

Background Information:

In 2001, the First International Symposium on Concussion in Sport was held in Vienna, Austria, organized by the International Ice Hockey Federation (IIHF), the Federation Internationale de Football Association - Medical Assessment and Research Centre (F-MARC), and the International Olympic Committee (IOC) Medical Commission. The purpose of this symposium was to provide recommendations aimed at improving the safety and health of athletes who suffer concussive injuries in sport.

From this symposium, a summarizing document was developed and published, providing health care professionals working in the sport arena with a resource to be used in guiding the management decisions of sport-related concussions.

Two main developments from this conference highlight the “Summary and Agreement Statement of the First International Conference on Concussion in Sport, Vienna 2001,” (1) and are as follows:

1) The Definition of Concussion:

Concussion was redefined as a complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces. Several common features that incorporate clinical, pathological, and biomechanical injury constructs that may be utilized in defining the nature of a concussive head injury include:
  • Concussion may be caused by either a direct blow to the head, face, neck, or elsewhere on the body with an “impulsive” force transmitted to the head.
  • Concussion typically results in the rapid onset of short-lived impairment of neurological function that resolves spontaneously.
  • Concussion may result in neuropathological changes, but the acute clinical symptoms largely reflect a functional disturbance rather than structural injury.
  • Concussion results in a graded set of clinical syndromes that may or may not involve loss of consciousness (LOC). Resolution of the clinical and cognitive symptoms typically follows a sequential course.
  • Concussion is typically associated with grossly normal structural neuroimaging studies. (1)
2) The Concussion in Sport Group Concussion (CISG) Protocol
  • Clinical History: The importance of questioning for a history of previous sustained symptoms of concussions was suggested. Similarly, the inclusion of previously sustained head, face, or neck injuries in the history was also advised due to their clinical relevance. Highlighting the proposed clinical history, however, were the variations of clinical outcomes to sustained impact including, but not limited to, differences in clinical manifestations, anatomical localization, biomechanical impact, genetic phenotype, and neuropathological change. Amnesia and Loss of Consciousness (LOC) were also addressed although their relationships to injury severity were reported equivocal. Several concussion grading scales were also recognized yet none were endorsed. Recommended however, was the utilization of measures of injury recovery to gauge severity/prognosis and guide return-to-play (RTP) decisions. Finally, for sideline evaluation of suspected concussions, a standardized post-concussion symptoms scale and neuropsychological (NP) testing were recommended.
  • Evaluation: Sideline NP test batteries, such as the Maddocks questions (2) and the Standardized Assessment of Concussion (SAC) (3), assessing attention and memory function, were reported essential to the concussion protocol. Signs and symptoms of acute concussion were also addressed and divided into three separate classifications: Cognitive features, Typical Symptoms, and Physical Signs.
  • Post-concussion neuropsychological assessment: It was the consensus of the CISG that NP testing, including baseline testing and serial follow-up, lie as one of the cornerstones of concussion evaluation.
  • Neuroimaging: In consideration of the fact that neuroimaging is usually normal in concussive injury, the CISG reported them nonessential for otherwise uncomplicated cases.
  • Research methods: The scientific value of a number and variety of research protocols were recognized. Such research was encouraged, especially at the elite and professional level, for the contribution of the science of concussion.
Management and rehabilitation:Three components were addressed:
  1. Acute response - Players should not be allowed to return to play in the game/practice that the injury was sustained. Players should not be left alone but be monitored regularly for deterioration. Players should undergo medical evaluation. RTP must follow a stepwise process that is medically supervised.
  2. Rehabilitation - A structured and supervised protocol was endorsed with the principle that all athletes be completely asymptomatic and have normal neurological and cognitive evaluations before starting a rehabilitation program.
  3. Stepwise return-to-play protocol - The recommended protocol progresses from complete rest to light aerobic and sport-specific exercise. Should the athlete be symptom free, he/she is allowed to move onto sport-specific and non-contact training drills, leading to full-contact training and game play with medical clearance. It was recommended that progression should only be made if asymptomatic and that athletes should drop back to the previous level if symptoms appear.
  • Prevention: The importance of rule changes and rule enforcement were reported in their role of reducing and preventing concussions.
  • Education: The education of athletes and their healthcare providers in concussion detection, its clinical features, assessment techniques, and principles of safe RTP were advocated.
  • Medical Considerations: It was acknowledged by the authors that management and RTP decisions be clinically and individually based.
  • Future: An important construct of this symposium and corresponding statement was the mandate given to an identified group (the CISG) to provide ongoing leadership in this field through progressive guideline development.
As a result of this mandate, the same group collaborated again in 2004 at the 2nd International Conference held in Prague, Czech Republic. To update their original document, the CISG developed and published a second statement (4) based on the current state of the literature and understanding of sport-related concussion at that time.

Several issues underlined the outcomes of this follow-up meeting:

Concussion grading scales:
The Prague group noted that the severity of concussion could only be retrospectively determined after all symptoms have resolved, a neurological examination is found normal, and cognitive function has returned to baseline.

Pediatric concussive injury:
Agreement was reached to apply all recommendations to children rather than adults alone. In addition, “cognitive rest” was introduced and described as the importance of limiting exertion pertaining to daily and scholastic activities while children are symptomatic.

Updated classification of concussion in sport:
One of the major developments of this conference and corresponding statement was the categorization of concussion into:
  • Simple concussion: Progressively resolving over 7-10 days without complication. Formal NP screening not necessary although mental status screening is standard. Management consisting of rest until full resolution of symptoms with graded RTP.
  • Complex concussion: Encompasses those cases that present with persistent symptoms, such specific sequelae as prolonged LOC, or prolonged impairment of cognitive function. Also falling into this category are multiple concussions or those occurring from an uncharacteristic or questionable (e.g.. low) force of impact. NP testing (by the appropriate personnel) is advised in these cases.
Pre-participation physical examinations:Novel to these examinations were the recommendations for:
  • A baseline cognitive assessment utilizing a Sport Concussion Assessment Tool (SCAT: see below) or computerized NP testing, and a symptom score to be compared in the event of a concussive injury
  • Baseline cognitive evaluations in all organized “high risk” sports, regardless of age or level of performance involved.
The sport concussion assessment tool (SCAT): This standardized tool, now second nature to most health care providers involved in “contact” sports, was a major development introduced by the 2nd symposium and based on the combination of eight existing assessment tools. Constructed into a double-sided, easy to carry card, this tool was created to act as a standardized method of evaluation for those athletes suffering from concussive injuries.

Objective balance assessments:
Also recommended as part of the clinical assessment and management protocol.

The role of pharmacological agents and medications:
The CISG discouraged these due to their (potential) effects on concussive symptoms and the RTP decision-making process. However, their importance in the management of specific, prolonged symptoms and for the modification of the condition’s underlying pathophysiology, was considered for those suffering only from complex concussions.

The Role of Sports Psychology:
The potential role of sports psychologists in the management of complex concussions was also introduced.

New Developments:

The 3rd and most recent symposium, including this consensus statement, was based on the need to address issues pertaining to acute simple concussion, return-to-play, complex concussion and long-term issues, pediatric concussion, and future directions.Additionally, this statement examines and addresses the management issues discussed in the previous symposia.
  • Updated classification of concussion in sport: The use of the terms “simple” and “complex” to classify concussion were abandoned at this symposium. Recognized was the fact that children and adolescents suffering from concussive injuries may undergo a longer recovery period.
  • Sideline evaluation of acute concussion: While the need for a thorough, post-injury evaluation was established since the first consensus statement, it was agreed that an appropriate medical assessment be performed in all cases and that rule modifications may be necessary in some sports in order for this to occur. Such modifications would enable a proper assessment to be performed without disrupting the game in play (e.g. rugby) or punishing the team involved (e.g. soccer).
  • Concussion management and same-day return to play: It was recognized that certain settings in adult athletics may have experienced personnel (e.g. neuropsychologists) and resources (e.g. neuroimaging) at their immediate disposal. In such situations, although RTP must follow the basic principles described above, its management may follow a more rapid process based in part on evidence collected from research in professional football (5). Strongly suggested, however, was the conservative treatment of younger athletes (<18 yoa) regardless of the available resources.
  • Modifying factors: Identified at this symposium were a range of specific modifiers with the potential to complicate cases and therefore, warrant advanced care and attention. It was suggested that a multidisciplinary team, led by an expert physician, manage cases presenting with such modifiers. Prolonged LOC (> 1 minute) was an example of such a modifier. Gender on the other hand, was reported inconclusive as a modifier; however, sex was accepted as a potential risk factor and/or influence of injury severity. Further, the presence of immediate motor signs and/or convulsions were reported to warrant no more than standard concussion management.
  • Children and adolescents: Updating from the above developments of the Vienna and Prague statements was the statement that the standard evaluation and management recommendations be applicable only to those 10 years of age and older. All assessments performed on athletes younger must include age-appropriate symptom checklists and possibly involve such parties as the athletes’ parents and educators. In addition, cognitive testing was recommended to be developmentally sensitive and performed by trained neuropsychologists especially in those presenting with learning and/or attention deficit hyperactivity disorders. Reiterated again was the importance of a more conservative RTP approach in this population, including the inappropriateness of a same-day RTP.
  • Elite athletes: It was recommended that while reality may not permit formal baseline NP screening in some instances, all organized high-risk sports should incorporate these assessments regardless of age or level of play.
  • The sport concussion assessment tool 2 (SCAT2): Aside from a revision of the original SCAT card, immediately noticeable was the inclusion of a “pocket” SCAT2 to the current document. On the front of this handy tool lies the symptom checklist while on the reverse lies questions to assess memory function and instructions for balance assessments.
No longer a convenient, double-sided assessment device, the SCAT2 now boasts four pages of examination resources to aid in the concussion assessment protocol. Specifically, the previously integrated evaluation components have been expanded to its original sources and the SCAT2 now incorporates the Glasgow Coma Scale (GCS), the Modified Maddocks Questionnaire and the Standardized Assessment of Concussion (SAC) as separate entities within. Identified in this tool is its potential use in baseline testing to assist in interpretation of post-injury test scores.

The quantification of injury evaluation plays a significant role in the updated SCAT2 and permits the tabulation of an “overall” test score. Unfortunately, however, a definitive “cut-off” score has yet to be determined and as stated below, must be subjected to validation. Useful though is the ability to isolate and quantify the SAC score for use in the management of a particular concussive event.

A section devoted to balance testing was also incorporated. This protocol was based on a modified version of the Balance Error Scoring System (BESS), and utilized the double leg, single leg, and tandem stances. Further, a finger-to-nose task was also included to isolate upper limb coordination. Finally, a detachable section on the final page permits the provision of advice to those sustaining a concussive injury.

Further Considerations:

Due to the many commonly held beliefs pertaining to concussion prevention, evaluation, and management that lack conclusive evidence, identified in this statement were key areas that warrant attention in future research endeavors. In particular, validating the SCAT2, clarifying pediatric paradigms, the role of virtual reality tools and clinical assessments lacking a baseline assessment, and long-term outcomes were a few of the areas needing clarification.

It was stressed that this statement was not intended to be utilized and interpreted as a standard of care but only as a guide in the management of sports-related concussions. Individualized treatment was regarded as the most reasonable model of care.

It was a request of the authors that the distribution of the SCAT2 and the consensus statement be distributed in its entirety and therefore, it is recommended that all readers of this review refer to the original document for a complete understanding.

The current document was stated to be formally reviewed and updated prior to December 1, 2012.

Study Methods:

This paper was a consensus statement developed and based on a summary of the findings from an international conference attended by a multidisciplinary group of expert health care professionals in the field of sport-related concussion. At the conclusion of the conference, a small group of experts (the CISG) drafted this working document, describing the agreement position attained by those in attendance.

Study Strengths / Weaknesses:

Not applicable.

Additional References:

  1. Aubry M, Cantu R, Dvorak J, et al. Summary and agreement statement of the first international conference on concussion in sport, Vienna 2001. The Physician and Sportsmedicine 2002; 30 (2): 57-62 (also co-published in British Journal of Sports Medicine 2002; 36: 3-7 and Clinical Journal of Sports Medicine 2002; 12: 6-12).
  2. Maddocks D, Dicker G, Saling M. The assessment of orientation following concussion in athletes. Clinical Journal of Sports Medicine 1995; 5 (1): 32-25.
  3. McCrea M, Kelly J, Randolph C, et al. Standardized assessment of concussion (SAC): on –site mental status evaluation of the athlete. Journal of Head Trauma and Rehabilitation 1998; 13 (2): 27-36.
  4. McCrory P, Johnston K, Meeuwisse W, et al. Summary and agreement statement of the 2nd international conference on concussion in sport, Prague 2004. Clinical Journal of Sports Medicine 2005; 15 (2): 48-55 (also co-published in British Journal of Sports Medicine 2005; 39 (4): 196-204, The Physician and Sportsmedicine 2005; 33 (4): 29-44, and Neurosurgery 2005; 59).
  5. Pellman E, Viano D, Casson I, et al. Concussion in professional football: players returning to the same game, part 7. Neurosurgery 2005; 56 (1): 79-92.