American Medical Society for Sports Medicine position statement: concussion in sport
Authors: Harmon Kimberly G , Drezner Jonathan A , Gammons Matthew , Guskiewicz Kevin M , Halstead Mark , Herring Stanley A , Kutcher Jeffrey S , Pana Andrea , Putukian Margot , Roberts William O 
Published: December 2012

Purpose of the statement▸ To provide an evidence-based, best practises summary to assist physicians with the evaluation and management of sports concussion.▸ To establish the level of evidence, knowledge gaps and areas requiring additional research.Importance of an AMSSM statement▸ Sports medicine physicians are frequently involved in the care of patients with sports concussion.▸ Sports medicine physicians are specifically trained to provide care along the continuum of sports concussion from the acute injury to return-to-play (RTP) decisions.▸ The care of athletes with sports concussion is ideally performed by healthcare professionals with specific training and experience in the assessment and management of concussion. Competence should be determined by training and experience, not dictated by specialty.▸ While this statement is directed towards sports medicine physicians, it may also assist other physicians and healthcare professionals in the care of patients with sports concussion.Definition▸ Concussion is defined as a traumatically induced transient disturbance of brain function and involves a complex pathophysiological process. Concussion is a subset of mild traumatic brain injury (MTBI) which is generally self-limited and at the less-severe end of the brain injury spectrum.Pathophysiology▸ Animal and human studies support the concept of postconcussive vulnerability, showing that a second blow before the brain has recovered results in worsening metabolic changes within the cell.▸ Experimental evidence suggests the concussed brain is less responsive to usual neural activation and when premature cognitive or physical activity occurs before complete recovery the brain may be vulnerable to prolonged dysfunction.Incidence▸ It is estimated that as many as 3.8 million concussions occur in the USA per year during competitive sports and recreational activities; however, as many as 50% of the concussions may go unreported.▸ Concussions occur in all sports with the highest incidence in football, hockey, rugby, soccer and basketball.Risk factors for sport-related concussion▸ A history of concussion is associated with a higher risk of sustaining another concussion.▸ A greater number, severity and duration of symptoms after a concussion are predictors of a prolonged recovery.▸ In sports with similar playing rules, the reported incidence of concussion is higher in female athletes than in male athletes.▸ Certain sports, positions and individual playing styles have a greater risk of concussion.▸ Youth athletes may have a more prolonged recovery and are more susceptible to a concussion accompanied by a catastrophic injury.▸ Preinjury mood disorders, learning disorders, attention-deficit disorders (ADD/ADHD) and migraine headaches complicate diagnosis and management of a concussion.Diagnosis of concussion▸ Concussion remains a clinical diagnosis ideally made by a healthcare provider familiar with the athlete and knowledgeable in the recognition and evaluation of concussion.▸ Graded symptom checklists provide an objective tool for assessing a variety of symptoms related to concussions, while also tracking the severity of those symptoms over serial evaluations.▸ Standardised assessment tools provide a helpful structure for the evaluation of concussion, although limited validation of these assessment tools is available.‘Sideline’ evaluation and management▸ Any athlete suspected of having a concussion should be stopped from playing and assessed by a licenced healthcare provider trained in the evaluation and management of concussions.▸ Recognition and initial assessment of a concussion should be guided by a symptoms checklist, cognitive evaluation (including orientation, past and immediate memory, new learning and concentration), balance tests and further neurological physical examination.▸ While standardised sideline tests are a useful framework for examination, the sensitivity, specificity, validity and reliability of these tests among different age groups, cultural groups and settings is largely undefined. Their practical usefulness with or without an individual baseline test is also largely unknown.▸ Balance disturbance is a specific indicator of a concussion, but not very sensitive. Balance testing on the sideline may be substantially different than baseline tests because of differences in shoe/cleat-type or surface, use of ankle tape or braces, or the presence of other lower extremity injury.▸ Imaging is reserved for athletes where intracerebral bleeding is suspected.▸ There is no same day RTP for an athlete diagnosed with a concussion.▸ Athletes suspected or diagnosed with a concussion should be monitored for deteriorating physical or mental status.Neuropsychological testing▸ Neuropsychological (NP) tests are an objective measure of brain–behaviour relationships and are more sensitive for subtle cognitive impairment than clinical exam.▸ Most concussions can be managed appropriately without the use of NP testing.▸ Computerised neuropsychological (CNP) testing should be interpreted by healthcare professionals trained and familiar with the type of test and the individual test limitations, including a knowledgeable assessment of the reliable change index, baseline variability and false-positive and false-negative rates.▸ Paper and pencil NP tests can be more comprehensive, test different domains and assess for other conditions which may masquerade as or complicate assessment of concussion.▸ NP testing should be used only as part of a comprehensive concussion management strategy and should not be used in isolation.▸ The ideal timing, frequency and type of NP testing have not been determined.▸ In some cases, properly administered and interpreted NP testing provides an added value to assess cognitive function and recovery in the management of sports concussions.▸ It is unknown if use of NP testing in the management of sports concussion helps prevent recurrent concussion, catastrophic injury or long-term complications.▸ Comprehensive NP evaluation is helpful in the post-concussion management of athletes with persistent symptoms or complicated courses.Return to class▸ Students will require cognitive rest and may require academic accommodations such as reduced workload and extended time for tests while recovering from a concussion.Return to play▸ Concussion symptoms should be resolved before returning to exercise.▸ A RTP progression involves a gradual, step-wise increase in physical demands, sports-specific activities and the risk for contact.▸ If symptoms occur with activity, the progression should be halted and restarted at the preceding symptom-free step.▸ RTP after concussion should occur only with medical clearance from a licenced healthcare provider trained in the evaluation and management of concussions.Short-term risks of premature RTP▸ The primary concern with early RTP is decreased reaction time leading to an increased risk of a repeat concussion or other injury and prolongation of symptoms.Long-term effects▸ There is an increasing concern that head impact exposure and recurrent concussions contribute to long-term neurological sequelae.▸ Some studies have suggested an association between prior concussions and chronic cognitive dysfunction. Large-scale epidemiological studies are needed to more clearly define risk factors and causation of any long-term neurological impairment.Disqualification from sport▸ There are no evidence-based guidelines for disqualifying/retiring an athlete from a sport after a concussion. Each case should be carefully deliberated and an individualised approach to determining disqualification taken.Education▸ Greater efforts are needed to educate involved parties, including athletes, parents, coaches, officials, school administrators and healthcare providers to improve concussion recognition, management and prevention.▸ Physicians should be prepared to provide counselling regarding potential long-term consequences of a concussion and recurrent concussions.Prevention▸ Primary prevention of some injuries may be possible with modification and enforcement of the rules and fair play.▸ Helmets, both hard (football, lacrosse and hockey) and soft (soccer, rugby) are best suited to prevent impact injuries (fracture, bleeding, laceration, etc.) but have not been shown to reduce the incidence and severity of concussions.▸ There is no current evidence that mouth guards can reduce the severity of or prevent concussions.▸ Secondary prevention may be possible by appropriate RTP management.Legislation▸ Legislative efforts provide a uniform standard for scholastic and non-scholastic sports organisations regarding concussion safety and management.Future directions▸ Additional research is needed to validate current assessment tools, delineate the role of NP testing and improve identification of those at risk of prolonged post-concussive symptoms or other long-term complications.▸ Evolving technologies for the diagnosis of concussion, such as newer neuroimaging techniques or biological markers, may provide new insights into the evaluation and management of sports concussion.