16 “if in doubt, sit them out” may ask questions repeatedly about what happened or what the score is. Concussed athletes will often have difficulty concentrating and answering specific questions. It is critical that all individuals dealing with potentially concussed athletes understand that concussion is an evolving phenomenon. Subtle symptoms and signs often become far more significant in the hours and days following the injury. Due to the evolving nature of the injury and the varied and potentially subtle symptoms and signs, the critical criteria for the diagnosis have been published based on a systematic review of the literature3,13 . The recommendations include an assessment looking at a variety of domains – loss of consciousness, symptoms, cognition, neurobehavioural symptoms, and balance – with any abnormality being a potential sign of concussion. Due to the complexity of the injury and the diagnostic challenge it can present, one of the outcomes from the series of International Consensus Conferences on Concussion in Sport was the development of the Sport Concussion Assessment Tool aimed at improving identification, clinical assessment and diagnosis of sport-related concussion9,14 . It is important to note that the diagnostic utility of the SCAT tool decreases 3 – 5 days post-concussion14 . Some of the football codes including Australian Football League, National Rugby League and Australian Rugby Union have developed criteria for mandatory removal of athletes from sport following head trauma. These criteria are intended to provide a decision-making algorithm for doctors to determine the requirement for removal from sport. The criteria are subdivided into those that require ‘immediate removal and no return to sport’ and those indicating ‘immediate removal from sport for further assessment with concussion assessment tools’. Clinical features that mandate ‘immediate removal and no return to sport’ include loss of consciousness, no protective action in fall to the ground directly observed or on video, impact seizure or tonic posturing, confusion, disorientation, memory impairment (e.g. fails Maddocks questions – see below), balance disturbance (e.g. ataxia), athlete reports significant, new or progressive concussion symptoms, dazed, blank/ vacant stare, not their normal selves or observed behaviour change. Where resources allow, sporting organisations could use modern technology such as instant video replay to enhance the ability to detect and manage concussion. However promising video is for the detection of concussion, there is currently not enough evidence to recommend its widespread use14 . Evidence-based assessment tools The Sport Concussion Assessment Tool 5th Edition (SCAT5) is the most recent version of the internationally recommended assessment tool updated at the Berlin 2016 International Consensus Conference on Concussion in Sport3,9,14 . The SCAT5 has been designed to assist medical professionals in the diagnosis of concussion. It is freely available online at bjsm.bmj.com/content/bjsports/early/2017/04/26/bjsports-2017-097506SCAT5. full.pdf. It is not intended to replace clinical judgment which remains the cornerstone of diagnosis for this condition. The tool encompasses a sideline assessment to be used at the time of the concussion, which includes a brief history of the injury, a Glasgow Coma Score and a series of questions known as Maddocks questions. These questions have been validated as an indicator of sport-related concussion and are more sensitive in this context than the standard orientation questions8 . The questions assess athlete orientation (in time and place) and they should be preceded by: ‘I am going to ask you a few questions, please listen carefully and give your best effort.’ The modified Maddocks questions are: > > What venue are we at today? > > Which half is it now? > > Who scored last in this match? > > What team did you play last week/game? > > Did your team win the last game? The remainder of the SCAT5 is for use off the field, as a sideline concussion assessment, in the medical room,