Cerebral concussion in athletes: Evaluation and neuropsychological testing

OBJECTIVE: To conduct a topic review of studies related to cerebral concuss ion in athletes, as an aid to improving decision-making and outcomes. METHODS: We review the literature to provide an historical perspective on t he incidence and definition of and the management guidelines for mild traum atic brain injury in sports. In addition, metabolic changes resulting from cerebral concussion and the second-impact syndrome are reviewed, to provide additional principles for decisionmaking. Neuropsychological testing, as i t applies to athletes, is discussed in detail, to delineate baseline assess ments, the characteristics of the neuropsychological evaluation, the neurop sychological tests used, and the methods for in-season identification of ce rebral concussion. future directions in the management of concussions are p resented. RESULTS: The incidence of cerebral concussions has been reduced from approx imately 19 per 100 participants in football per season to approximately 4 p er 100, i.e., 40,000 to 50,000 concussions per year in football alone. The most commonly used definitions of concussion are those proposed by Cantu an d the American Academy of Neurology. Each has associated management guideli nes. Concussion or loss of consciousness occurs when the extracellular pota ssium concentration increases beyond the upper normal limit of approximatel y 4 to 5 mmol/L, to levels of 20 to 50 mmol/L, inhibiting the action potent ial and leading to loss of consciousness. This phenomenon helps to explain the delayed effects of symptoms after trauma. CONCLUSION: Neuropsychological testing seems to be an effective way to obta in useful data on the short-term and long-term effects of mild traumatic br ain injury. Moreover, knowledge of the various definitions and management s trategies, as well as the utility of neuropsychological testing, is essenti al for those involved in decision-making with athletes with mild traumatic brain injuries.