Quarterback Alex Smith (11) of the San Francisco 49ers gets hit by linebacker Jo-Lonn Dunbar (52) of the St. Louis Rams during a run in the first quarter on November 11, 2012 at Candlestick Park in San Francisco, California. Smith later left the game with a concussion.
Credit: Photo by Brian Bahr/Getty Images
Jay Cutler (6) of the Chicago Bears is hit by Kareem Jackson (25) of the Houston Texans at Soldier Field on November 11, 2012 in Chicago, Illinois. Cutler later left the game with a concussion.
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Atlanta Falcons defensive end John Abraham (55) stands over injured Philadelphia Eagles quarterback Michael Vick (7) in the second half at the Georgia Dome in Atlanta on Sunday, Sept. 18, 2011. Vick left with what was described as a concussion after getting spun by a Falcons rusher into Eagles lineman Todd Herremans.
Vick's status unclear after concussion
Credit: AP Photo/Butch Dill
Quarterback Troy Aikman of the Dallas Cowboys ices the back of his neck as he recovers from a concussion during a preseason game against the Oakland Raiders at Oakland/Alameda County Coliseum on Aug. 18, 1990 in Oakland, Ca. Aikman suffered 10 concussions in his 12-year career.
Credit: Getty Images/George Rose
Team officials and trainers examine Orlando Magic guard Nick Anderson as he lies face down on the court after colliding with Rafael Addison of the Detroit Pistons in the second quarter on April 5, 1995 in Orlando, Fl. After ten minutes, Anderson was removed on a stretcher and taken to Florida Hospital where it was determined that he had suffered a severe concussion.
Credit: Getty Images/Tony Ranze
San Francisco 49ers quarterback Steve Young (8) picks himself up off the turf of the Georgia Dome in Atlanta on Saturday, Jan. 9, 1999. Young was plagued by concussions throughout his career. Officially, Young had suffered seven concussions, but many believe the number to be higher.
Credit: AP Photo
Players from the Philadelphia Flyers and the New Jersey Devils scuffle in the background as Flyers Eric Lindros (88) lies on the ice after getting hit in the first period of Game 7 of the Eastern Conference finals in Philadelphia, May 26, 2000. While the NHL Players' Association has pitched a ban of all hits to the head, the league hadn't moved to adopt such a rule. But for the first time, change appears possible. His story isn't unique, and as more research is done, the danger of concussions and their long-term effects become increasingly clear. Concussions plagued the careers of Hall of Famer Pat LaFontaine, Eric Lindros and his brother Brett, star goalie Mike Richter, defenseman Jeff Beukeboom and countless others.
Credit: AP Photo/George Widman
New York Mets battter Mike Piazza lies in the dirt after being hit by a pitch thrown by New York Yankees pitcher Roger Clemens during the first inning of the second game of their cross-town doubleheader Saturday, July 8, 2000 in New York. The first game was at Shea Stadium. Piazza left the game with a concussion.
Credit: AP Photo/Mark Lennihan
Brad May (32) of the Vancouver Canucks is removed from the ice on a stretcher with a concussion after being hit by Mats Sundin (13) of the Toronto Maple Leafs at General Motors Place on March 15, 2003 in Vancouver, Canada.
Credit: Getty Images/Jeff Vinnick
Tackle Kyle Turley (68) of the St. Louis Rams is carted off the field during the game against the Detroit Lions on December 28, 2003 at Ford Field in Detroit, Michigan. The Lions upset the Rams 30-20.
Credit: AP/Kyle Ericson, Paul Sancya
Linebacker Ted Johnson (52) of the New England Patriots reaches out to bring down wide receiver Antwaan Randle El (82) of the Pittsburgh Steelers in the AFC championship game at Heinz Field on January 23, 2005 in Pittsburgh, Pa. In 2007 Johnson told the New York Times that he suffers from amphetamine addiction, depression and headaches related to post-concussion syndrome and Second Impact Syndrome.
Credit: Getty Images/Andy Lyons
Colorado Avalanche forward Steve Moore is attended to by the team trainer after being injured in a fight with Vancouver Canucks Todd Bertuzzi in Vancouver, British Columbia, Monday, March 8, 2004. A pool of blood formed around Moore's head as he lay motionless on the ice. A stretcher was wheeled out and after a delay of nearly 10 minutes Moore was taken off for medical attention. Moore where he was treated for three fractured vertebrae in his neck, a grade three concussion, vertebral ligament damage, stretching of the brachial plexus nerves, and facial lacerations. He was also suffering from amnesia. The incident ended Moore's hockey career.
Credit: AP Photo/Chuck Stoody
New York Mets' centerfielder Carlos Beltran, left, and rightfielder Mike Cameron collide while trying for a diving catch on a bloop fly off the bat of San Diego Padres' David Ross in the seventh inning Thursday Aug. 11, 2005 in San Diego. Cameron suffered a concussion and multiple fractures of his nose and cheekbones, and was removed from the field on a stretcher, he would miss the remainder of the season. Beltran also suffered a concussion but was able to walk off the field with help.
Credit: AP Photo/Lenny Ignelzi
Jason Robinson of the Sale Sharks lies on the ground after suffering a concussion during the Guinness Premiership match against the Worcester Warriors on Feb. 11, 2006 in Worcester, England.
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Gerald Wallace of the Charlotte Bobcats suffered a Grade 3 concussion after getting knocked in the face by Mikkie Moore of the Sacramento Kings during their game at Bobcats Arena on Feb. 22, 2008 in Charlotte, North Carolina. It was his fourth concussion in four seasons and he was unable to fly with the team, choosing to take a bus.
Credit: Getty Images/Streeter Lecka
New York Mets right fielder Ryan Church, left, and first baseman Marlon Anderson collide in right field as they chase a fly ball at a spring training game in Port St. Lucie, Fla., Saturday, March 1, 2008. Church suffered a second concussion in May and spend most of the 2008 season inactive.
Credit: AP Photo/Nati Harnik
Buffalo Bills QB Trent Edwards suffers a concussion after getting hit by strong safety Adrian Wilson (24) of the Arizona Cardinals during the first half on Oct. 5, 2008 at Stadium in Glendale, Arizona. Edwards suffered another concussion in 2009 and missed several games.
Credit: Getty Images/Donald Miralle
New York Mets David Wright goes down after being beaned by a pitch by San Francisco Giants pitcher Matt Cain at Citi Field, New York, on August 15, 2009. Wright suffered a concussion and spent several weeks on the disabled list and his production at the plate declined the remainder of the season.
Credit: CBS/Gordon Donovan
The Boston Bruins lean over fallen teammate Marc Savard after taking a hit in the third period against the Pittsburgh Penguins in Pittsburgh, Sunday, March 7, 2010. Savard, who was taken from the ice on a stretcher, was out for the remainder of the regular season and until the second round of the Eastern Conference playoffs. Due to post-concussion syndrome, he didn't play in the 2010-11 season until Jan. 2
Credit: AP Photo/Keith Srakocic
Justin Morneau of the Minnesota Twins sustained a concussion on July 7, 2010, when he slid into the knee of Toronto's John McDonald trying to break up a double play. The former AL MVP missed the remainder of the season with the effects of post-concussion syndrome.
Credit: Getty Images/Jed Jacobsohn
Jason Bay of the New York Mets looks on from the dugout against the Houston Astros on Aug. 28, 2010 at Citi Field in New York City. Bay suffered a concussion earlier in the week while running into the outfield wall in Los Angeles and missed the remainder of the season.
Credit: Getty Images/Jim McIsaac
New York Giants defensive end Osi Umenyiora, hits Chicago Bears quarterback Jay Cutler, right, to break up a pass attempt during the first quarter at New Meadowlands Stadium Sunday, Oct. 3, 2010, in East Rutherford, N.J. The Giants, who had nine sacks, knocked out Cutler with a concussion. The QB missed the remainder of that game and the following week.
Credit: AP Photo/Seth Wenig
Pittsburgh Steelers linebacker James Harrison (92) hits Cleveland Browns wide receiver Mohamed Massaquoi (11) after Massaquoi tried to catch a pass in the second quarter, Sunday, Oct. 17, 2010, in Pittsburgh. Harrison was fined $75,000 for the helmet-to-helmet hit that left Massaquoi with a concussion.
Credit: AP Photo/Keith Srakocic
Defenders T.J. Ward (43) and Eric Wright (21) of the Cleveland Browns break up a pass to wide receiver Jordan Shipley (11) of the Cincinnati Bengals at Cleveland Browns Stadium on October 3, 2010 in Cleveland, Ohio. Shipley had to be taken off the field with a concussion and did not return to the game. Cleveland Browns safety Ward was fined $15,000.
Credit: Getty Images/Matt Sullivan
Andrew Quarless (81) and Tom Crabtree (83) of the Green Bay Packers help teammate Aaron Rogers (12) up during the second quarter of the game against the Detroit Lions at Ford Field on December 12, 2010 in Detroit, Michigan. Rodgers was pulled from the game after sustaining his second concussion of the season.
Credit: Getty Images/Leon Halip
Pittsburgh Steelers tight end Heath Miller (83) laying on the field after being hit by Linebacker Jameel McClain (53) of the Baltimore Ravens on Sunday, December 5, 2010 at M&T Bank Stadium in Baltimore, Maryland. Miller suffered a concussion.
Credit: Getty Images/Larry French
Sidney Crosby (87) of the Pittsburgh Penguins battles for the puck against Mike Green (52) of the Washington Capitals during the 2011 NHL Bridgestone Winter Classic at Heinz Field on Jan. 1, 2011 in Pittsburgh, Pa. Crosby was hurt in the game when Capitals forward David Steckel's shoulder struck him in the head as Steckel chased the play up ice. Crosby then took a hit from behind by Tampa Bay Lightning defenseman Victor Hedman in the next game, causing him to miss games.
Credit: Getty Images/Jamie Sabau
Montreal Canadiens' Max Pacioretty lays on the ice after taking a hit by Boston Bruins' Zdeno Chara during the second period on, Tuesday, March 8, 2011, in Montreal. Pacioretty suffered a severe concussion and fractured vertebra after being thrown into a stanchion by Chara, who received a game misconduct from the referees but no further sanction by the NHL.
Hockey hit spurs police probe, sponsorship threat
Credit: AP Photo/The Canadian Press, Paul Chiasson
New York Giant Rodney Hampton (top) is tackled near the goal line, after a six-yard gain, by the Chicago Bears' Marty Carter in a Nov. 1995 file photo. According to TMZ, Hampton is among 75 players suing the NFL, claiming it intentionally hid the harmful effects of concussions.
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