Brain injury may last longer than a year after return-to-play clearance following concussion

A team from the University of Toronto (ON, Canada) discovered that signs of brain damage are still visible in MRI scans a year after athletes returned to play.

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A study published in Neurology reported that athletes may still not be fully recovered from brain injury caused by concussion a year after being allowed to return to play.  

A team of researchers from the University of Toronto (ON, Canada) investigated college athletes who participated in various sports such as volleyball, hockey and football. Men and women were equally represented within the sample and a total of 24 participants had concussion while 122 participants did not.  

The team used MRI to assess the athletes with concussion 4 days after injury, once they were cleared to play and one year after return to play. These scans were compared with the control group MRI scans from the beginning of the season, which displayed the concussed athletes still displayed signs of brain injury when they were returning to play and a year after.  

"         There is growing evidence that recovery from a concussion may not be complete even when symptoms such as headache and dizziness are gone and the athlete is allowed to return to play, so it is important to determine if various aspects of the brain injury resolve over time or are perhaps permanent," commented study author Nathan W. Churchill (St. Michael's Hospital; ON, Canada). "Our research looked at the brain one year after return to play in a group of college athletes and found that evidence of brain injury from concussion remained in some parts of the brain." 

The researchers also noted that the blood flow of concussed individuals significantly reduced, by 10 millilitres per 100 grams of blood per minute, a year after return to play when compared with the healthy individuals. Furthermore, the team discovered that the concussed athletes still showed signs of tissue swelling after they mapped water molecules in the white matter of their brains.  

However, when the team investigated patterns of resting brain activity on the grey matter and lines of communication in the white matter, they discovered that brain connectivity returned to normal a year after. These findings indicating that there are some signs of recovery following their return to play.   

"        The principal finding of this study was that different aspects of brain physiology have different patterns of long-term recovery," explained Churchill. "These findings significantly enhance our understanding of the natural course of brain recovery after a concussion. Future studies are needed to look beyond one year after return to play to see if these longer-term brain injuries eventually heal or remain permanent." 

The researchers matched each concussed athlete to a group of control athletes based on age, sex and previous concussion history. However, the study was limited by the fact the concussed athletes did not have brain scans before their injuries, which could have been used to control other potential confounding variables.  

Source: Churchill NW, Hutchison MG, Graham SJ and Schweizer TA. Mapping brain recovery after concussion.  From acute injury to 1 year after medical clearance. Neurology. doi:10.1212/WNL.0000000000008523 (2019) (Epub ahead of print);

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