Halverson took a punch in the chin, one of dozens he'd absorbed in a nine-year pro career. But his life changed dramatically after this blow. He couldn't remember names. He was constantly tired, yet couldn't sleep. His mood would darken without warning and his sense of hunger disappeared.
Exertion brings on pounding headaches and simple tasks sometimes go awry.
Ndur couldn't drive for a month after his injury and had trouble balancing or concentrating enough to read. The road back from a concussion isn't clearly marked. The NHL and NFL have ongoing studies on the subject, but what conclusions they'll reach and how much impact they'll have remain unknown. In recent years, the NHL has required every player to undergo neuropsychological testing. It measures each player's baseline of mental acuity, including spatial and visual awareness and memory, and provides a basis for comparison after concussions.