Baseline Reference Values for Concussion Assessments in Football

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 deficits 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-term, medium-term, and long-term consequences.

Diagnosing and determining the severity of a SRC immediately on- or off-field is challenging, especially because clinical signs can evolve after the mechanism of injury. Since 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. Nevertheless, an immediate, targeted assessment to support clinical decision-making is of great importance and helps 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. 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 and memory function through 8 different domains. For further assessment of neurocognitive deficits and to inform return to play decisions, the Immediate Post-Concussion Assessment and Cognitive Testing tool version 4 (ImPACT) can also provide valuable information. The 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.

Post-injury assessments can be compared to the player's assessment results from a non-concussed state (baseline assessment), adding more useful information to their interpretation. Unfortunately, many players do not have baseline assessments performed. Therefore, reference values from similar population groups can act as comparator to determine severity and progression of signs and/or symptoms. Reference values are reported in several sports, but values specific to football players are lacking.

The primary objective is to provide normal concussion assessment references values for use in football.