Concussion, in tennis??
Victoria Azarenka collapses in match. http://sports.espn.go.com/sports/tennis/usopen10/news/story?id=5519516
When in Doubt, Sit Out!
A recent article in Time Magazine outlines details of a study that says kids are returning to sports too soon after suffering from concussions.
Studies Show ER Visits for Concussions on the Rise for Young Athletes
Concussions Sending More Young Athletes to ER