Anthony P. Kontos and Jamie McAllister-Deitrick
Concussions affect millions of athletes of all ages each year in a variety of sports. Athletes in certain sports such as American football, ice hockey, rugby, soccer, and combative sports like boxing are at higher risk for concussion. Direct or indirect mechanical forces acting on the skull and brain cause a concussion, which is a milder form of brain injury. Conventional neuroimaging (e.g., computerized tomography [CT], magnetic resonance imaging [MRI]) for concussion is typically negative. Concussions involve both neurometabolic and subtle structural damage to the brain that results in signs (e.g., loss of consciousness [LOC], amnesia, confusion), symptoms (e.g., headache, dizziness, nausea), and functional impairment (e.g., cognitive, balance, vestibular, oculomotor). Symptoms, impairment, and recovery time following concussion can last from a few days to weeks or months, based on a variety of risk factors, including younger age, female sex, history of concussion, and history of migraine. Following a concussion, athletes may experience one or more clinical profiles, including cognitive fatigue, vestibular, oculomotor, post-traumatic migraine (PTM), mood/anxiety, and/or cervical. The heterogeneous nature of concussion warrants a comprehensive approach to assessment, including a thorough clinical examination and interview; symptom inventories; and cognitive, balance, vestibular, oculomotor, and exertion-based evaluations. Targeted treatment and rehabilitation strategies including behavior management, vestibular, vision, and exertion therapies, and in some cases medication can be effective in treating the various concussion clinical profiles. Some athletes experience persistent post-concussion symptoms (PCS) and/or psychological issues (e.g., depression, anxiety) following concussion. Following appropriate treatment and rehabilitation strategies, determination of safe return to play is predicated on being symptom-free and back to normal levels of function at rest and following exertion. Certain populations, including youth athletes, may be at a higher risk for worse impairment and prolonged recovery following concussion. It has been suggested that some athletes experience long-term effects associated with concussion including chronic traumatic encephalopathy (CTE). However, additional empirical studies on the role of concussion on CTE are needed, as CTE may have multiple causes that are unrelated to sport participation and concussion.