11 articles in the December issue of Neurosurgical Focus are dedicated to concussions in sports, focusing on methods of diagnosing concussion and evaluating its consequences, structural and functional changes that can occur in the brain following concussion, and changing attitudes and legislation concerning sports that traditionally carry risks of brain injury.

Concussion, also called mild traumatic brain injury (TBI) by virtually no one outside concussion article writing, has been hyped into a "silent epidemic" in 2012 because the event and its consequences, such as cognitive and behavioral changes, may be subtle and are not always recognized, which means they can be correlated to almost anything.

A prospective study of physician-observed concussion during a varsity university hockey season looks at findings of the Hockey Education Concussion Project (HECP), which focuses on concussions sustained by male and female college hockey players in Canada. They discuss the incidence of concussion during hockey games, neuropsychological changes following concussion, and changes in hockey players' white matter and brain metabolism over the course of the hockey season.

They added magnetic resonance imaging (MRI) to neuropsychological tests to follow players' physiological and mental health over an entire season. They administered the MRI studies and neuropsychological assessments (ImPACT and SCAT2) to college hockey players at the beginning of the season, after a diagnosed concussion, and at the end of the season. In addition, physician and non-physician observers were present at games, where they could recognize signs and symptoms of concussion on the spot. 

The incidences of game-related concussions were lower than stated in a 2010 hockey study, but still three times higher in male hockey players and five times higher in female players than those found by other authors, so they are really, really looking. They found an incidence in female players substantially higher than that in male players: 14.93 vs. 7.50 per 1000 athlete exposures during the regular season games.

The authors believe that they are not looking too hard but rather that hockey-associated concussion is underreported and indicate that the current definition of concussion may need to be reexamined. The authors also describe their experiences in conducting the study during hockey games, working with coaches, trainers, and players. Cultural attitudes about hockey and reticence on the part of team members, leaders, and others to report concussion events are discussed.

In the same issue, an overview of what is known about the forces involved in the primary phase of concussion as well as immediate and secondary cellular events that lead to the secondary phase of this TBI is provided by Matthew Dashnaw, Anthony Petraglia, and Julian Bailes. These authors point out that a thorough understanding of the basic processes of concussion and subconcussion must exist in order to prevent and treat the consequences of these injuries.

Scott Zuckerman and colleagues focus on more severe sequelae of sports-related concussions such as subarachnoid, epidural, and subdural hemorrhage, as well as malignant cerebral edema—medical emergencies frequently requiring the services of a neurosurgeon. They conducted PubMed searches on structural brain injuries arising from sports-related concussions and found 40 articles describing individual cases and small patient series.

The lack of prospective cohort series led the authors to suggest the creation of a prospective registry of these injuries, which would be of great benefit to neurosurgeons dealing with severe consequences of concussion.

A review of the literature on the associations between biomechanical parameters and concussions sustained by helmeted players in American football is reported by Jonathan Forbes and coworkers. They state that the existing data are insufficient to predict the occurrence of concussion based on biomechanical data and suggest that further research is necessary.

In a separate study, patients who sustained a concussion from a motor vehicle accident or a sports mishap and healthy volunteers performed working memory tasks while electrophysiological testing measured event-related potential (ERP) waves in their brains. Nadia Gosselin and colleagues found cerebral dysfunction in the patients with concussions, as indicated by both poor performance on the memory tasks and abnormal ERP waves; the abnormal ERP waves were identified even in patients in the nonacute stage of TBI. The same group of researchers also contributed another paper in which they review long-term alterations in cognitive and motor function following sports-related concussion, which were detected using modern brain investigation techniques. In the second paper, the authors provide new insights into the neuropathophysiology of sports-related concussion.

Magnetoencephalographic virtual recording during language/spatial tasks was examined by Matthew Tormenti and colleagues as a potential diagnostic tool for concussion. Based on their findings, the authors suggest that with some refinements, magnetoencephalographic virtual recording may become a useful noninvasive diagnostic tool.

The status of sport-related concussion legislation in the United States is discussed by Krystal Tomei et al. These researchers compared state laws regarding concussion education, criteria for removal from play, and which individuals are allowed to evaluate a player and clear this individual for return to play. The authors found that concussion legislation has been passed in 43 states and the District of Columbia, and is pending in another 4 states.