Sidney Crosby's planned 15 minutes on the ice against the New York Rangers Thursday night mark his first hockey game more than three months after being once again sidelined by concussion-like symptoms.
The Pittsburgh Penguins star has experienced dizziness and headaches since the beginning of 2011, when he suffered a concussion in January after playing the Washington Capitals and the Tampa Bay Lightning. He returned briefly in November, to much fanfare, but was quickly taken out of the rink after his symptoms returned.
Concussions, according to the Mayo Clinic, occur when the brain is damaged, usually by something like a blow to the head, or even a violent shaking of the head and upper body.
Often, it takes just a few days to heal from a concussion, but it can take months, according to the MedlinePlus Medical Encyclopedia.
In the longer term, multiple concussions over an extended period have been linked to neurodegenerative diseases. For example: boxer Muhammad Ali, who developed Parkinson's disease after years of taking blows to the head.
On the bright side, concussion rates seem to be falling in hockey. A 2008 study in the Canadian Journal of Neurological Sciences found that over the decade studied, the incidence of concussions among NHL players fell from a high of 1.81 per 1,000 athlete exposures (in the 1998-99 season) to 1.04 per 1,000 exposures (in 2005-06).
But perhaps it's a sign that attitudes toward managing concussions have been changing. The average time lost from play actually increased over that period -- either because players are getting hurt worse or, the authors write, because of "increased adherence to modern management guidelines preventing premature return to play."
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