One of the most challenging problems faced by medical personnel responsible for the health care of athletes is the recognition and management of concussions.40,53 Concussions can be defined as any alteration in cerebral function caused by a direct or indirect (rotation) force transmitted to the head resulting in one or more of the following acute signs or symptoms: a brief loss of consciousness, lightheadedness, vertigo, cognitive and memory dysfunction, tinnitus, blurred vision, difficulty concentrating, amnesia, headache, nausea, vomiting, photophobia, or a balance disturbance. Delayed signs and symptoms may also include sleep irregularities, fatigue, personality changes, an inability to perform usual daily activities, depression, or lethargy. Although many concussions are mild, the range of injury is wide. Nevertheless, concussions are a form of traumatic brain injury. In recent years, these injuries have captured many news headlines as several professional football and hockey players have retired because of the effects of concussions. Interestingly, depending on the nature of the sport and the type (for example, rotation) and degree of contact expected, these injuries are many times viewed as just “part of the game.” While many of these injuries are minor, some can be quite serious, with long-term consequences. Therefore, early detection through a thorough knowledge of the signs and symptoms and specific documentation of the injury is critical to the management of concussion and the monitoring of the natural history of the injury.36,40 Unfortunately, attempts to characterize and classify the spectrum of concussions by stratifying the signs and symptoms as indicators of relative severity have been difficult.7,10 Yet the need to accurately diagnose the severity of these injuries is obvious, especially at the time of injury when the triage decision could be critical to the patient’s future. Returning an injured athlete to competition when the brain needs time to recover is an obvious concern. One of the reasons for concern is the secondimpact syndrome,24,29,52,59 a rare but ominous consequence of an untimely blow to a vulnerable central nervous system. While recent reviews cast a shadow of doubt on the occurrence and frequency,51 the catastrophic nature of these events requires its consideration in the evaluation and treatment of concussions. Also, the cumulative effects of repeated injuries, even mild injuries, over time remains a serious concern to those involved in sports medicine.15 The fact that some athletes do not recover as * Address correspondence and reprint requests to Edward M. Wojtys, MD, University of Michigan, MedSport, Domino Farms, POB 363, Ann Arbor MI 48106. No author or related institution has received financial benefit from research in this study. See “Acknowledgment” for funding information. 0363-5465/99/2727-0676$02.00/0 THE AMERICAN JOURNAL OF SPORTS MEDICINE, Vol. 27, No. 5 © 1999 American Orthopaedic Society for Sports Medicine 676 expected from concussions and are hampered by persistent symptoms for weeks or months is troublesome. In 1999, a complete understanding of the pathobiology of cerebral concussion is still lacking,66 as is an explanation as to why the brain of some athletes may become so vulnerable to secondary injury after a seemingly mild insult. Because of these lingering concerns, an American Orthopaedic Society for Sports Medicine-sponsored Concussion Workshop was held in December 1997 to assemble representatives from the medical community who routinely diagnose and treat these injuries in athletes. Invited participants included health-care professionals who perform research on brain injuries, a variety of clinicians responsible for the care of the athlete, and representatives of organized contact sports (NFL, NHL, NCAA). These representatives met with the hope of defining areas of agreement and disagreement in the detection and management of concussion in sports. Realizing that differences do exist among clinicians regarding the safety of return-to-play at various time points after concussion, defining areas of disagreement was also a goal of the concussion workshop so that these differences could be subjected to discussion and investigation. Lastly, participants focused on the key elements of the initial evaluation of concussion so that data collection, future studies, and follow-up reports could benefit from the use of common terminology and evaluation tools.