Concussion Assessments in Football Competitions Participating in the IFAB's Permanent Concussion Substitution Trial

1 INTRODUCTION

Concussions represent a subset of traumatic brain injury (TBI), pragmatically described as a "traumatically induced transient disturbance of brain function caused by a complex physiological process". A sports-related concussion (SRC) can result in substantially different outcomes, ranging from no detectable effects to transient functional impairments or even life-threatening complications. While the immediate effects of most concussions are short-lived, typically resolving within days, athletes who continue to play following a concussive event may increase their risk of developing short-, medium-, and long-term consequences.

TBI and SRC in football have received increased attention from medical and scientific communities, sports organisations, legislators, the media, as well as the general population. Consistency in the identification of concussed footballers and their subsequent management and rehabilitation has received particular focus. It is apparent that the management of suspected and confirmed concussive events are prominent and contentious issues in football. Incidence of SRC varies considerably across studies, which may be largely due to methodological differences. During 51 FIFA affiliated tournaments and 4 Olympic Games from 1998 to 2012, 3944 injuries were reported by the Team Physicians, of which 577 (15%) affected the head or neck. Eighty-one injuries (2% of all injuries) were given the diagnosis of concussion. It is pertinent to more accurately establish the incidence of head trauma and concussive injuries as allows risk exposure to be better understood.

Diagnosing and determining the severity of a SRC immediately on- or off-field is challenging, especially because clinical signs can evolve minutes to hours after the mechanism of injury. Hence, repeated follow-up and serial assessments of a player are recommended following such an injury. Combined injuries of the central and peripheral nervous systems are frequent, determining the locus of injury and therefore underlying explanation for symptoms is difficult and often not possible on- or off-field requiring a more focussed examination. Thus, the diagnosis and estimation of injury severity on- or off-field is a major challenge for the personnel performing an assessment. Specific predictors of injury severity, prognosis and the likely temporal resolution of symptoms are yet to be determined in a football population. Nevertheless, an immediate, targeted and standardised assessment approach to support clinical decision-making is of great importance, and despite unanswered research questions in this specific population, it does help to guide the management approach.

Current advice, when a player sustains a confirmed or suspected concussive injury, is to remove them from play immediately and not return to competition or unrestricted training until signs and symptoms have been managed as per relevant guidelines. To support this decision the International football Association Board has introduced a trial allowing an additional permanent concussion substitution in participating competitions. Follow-up assessment of concussion incidents is recommended to include the Sport Concussion Assessment Tool 5th Edition (SCAT5). The SCAT5 is a standardized tool for use by healthcare professionals in the evaluation of individuals aged 13 years or older, who are suspected of having sustained an SRC. It comprises a neuropsychological test battery that assesses attention, memory and neurological function through 8 different domains. It's particular utility is in the immediate assessment of the athlete and in the first 3-5 days following the incident, subsequently it can be used to track symptom resolution. For further assessment of neurocognitive deficits and to inform return to play decisions, it is recommended that a computerised assessment is also adopted. The Immediate Post-Concussion Assessment and Cognitive Testing tool version 4 (ImPACT) is a computer-based neurocognitive test battery that provides an objective measure of neurocognitive functioning as an assessment aid in the management of concussed individuals aged 12-80 years. The application of these two assessment modalities and their ability to inform clinical-decision making regarding concussion diagnosis in a football population has not been considered before, this includes whether their utility differs if compared to individual or normative baseline neurocognitive assessment values.