Concussion damage may linger a full year after an athlete returns to play, Canadian researchers report.
"Brain recovery after concussion may be a more complex and longer-lasting process than we originally thought," said lead investigator Nathan Churchill, a research associate in the Neuroscience Research Program at St. Michael's Hospital in Toronto.
Reduced blood flow to the brain
After a concussion, he said doctors usually clear athletes for play when symptoms disappear. But this new study, which relied on a series of MRI scans, suggests subtle brain damage may persist even when symptoms like headaches and concentration problems improve.
"These findings raise questions about when, if ever, the brain returns to normal, and if these brain changes translate into a worse outcome if athletes have another concussion before recovery is complete," Churchill said.
For the study, he and his colleagues collected data on 24 college athletes who had suffered concussions and 122 who hadn't. Males and females were equally represented, and their sports included volleyball, hockey, soccer, football, rugby, basketball, lacrosse and water polo.
Participants with concussions had brain MRIs right after their injury and again when they returned to play. They also had a brain scan a year later. Athletes with no concussion had one brain scan at the start of their seasons.
Churchill's team found that players who had concussions had signs of brain injury when they returned to play and a year after that. There was significantly reduced blood flow to the brain, both when athletes returned to play and a year later. Signs of brain swelling were also noted on both scans.
Despite these findings, brain activity and connectivity between brain cells had returned to normal after a year, the researchers said. The extent of brain injury depended on symptom severity right after the concussion and how long the athlete was benched.
A lot more research needed
The findings suggest different areas of the brain may take longer to recovery from a head injury. But the significance of this residual brain damage remains to be seen, one expert said.
Dr John Kuluz is director of traumatic brain injury and neurorehabilitation at Nicklaus Children's Hospital in Miami. He reviewed the study and said he isn't sure this damage is significant or if it plays any role in an athlete's ability to return to the game.
"It isn't clear if seeing those changes and no symptoms makes a lot of difference in terms of the player's recovery," said Kuluz. "I was always taught as a clinician when looking at an X-ray, or a CAT scan or an MRI, you treat the patient, not the scan."
A lot more research is needed to see how relevant these brain changes are, he said.
"It's not ready for clinical use, and no one should be taking their child or their athlete to get one of these MRIs so they can figure out how to manage a concussion or how bad it is and when they're going to get better," Kuluz said.
The report was published online in the journal Neurology.
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