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Concussion effects may linger on MRI 1 year after athletes resume play



Among athletes with concussion, the effects of the injury on brain physiology may persist when they return to play and 1 year later.

MRI measures from 24 athletes with concussion significantly differed from those of controls at various time points and changed over time, according to a study published in Neurology. “Different aspects of brain physiology have different patterns of long-term recovery,” the researchers wrote.

While guidelines for safe return to play mainly rely on the resolution of symptoms, “the findings in this study indicate that more research is needed ... to better understand optimal recovery time from a biological standpoint,” wrote first author Nathan W. Churchill, PhD, a researcher at St. Michael’s Hospital in Toronto, and colleagues.

The study provides “evidence of incomplete or ongoing recovery” when athletes return to play, which could entail “a potential risk for long-term sequelae, given the evidence of worse outcomes if a second concussion occurs before recovery is complete,” according to the investigators. In addition, the study reinforces that neurobiological recovery varies across individuals and might depend on the initial clinical presentation.

To examine whether concussion-related brain changes dissipate by 1 year after athletes receive medical clearance to return to play, Dr. Churchill and colleagues analyzed MRI data from 24 college athletes with concussion and 122 control athletes without concussion.

Athletes with concussion were scanned within 1 week of the injury, at return to play a median of 27 days after the concussion, and 1 year after return to play. Control athletes were scanned before the start of the season. Participants’ sports included volleyball, hockey, soccer, football, rugby, basketball, lacrosse, and water polo. The participants had a mean age of about 20 years, and about half were women.

Athletes with concussion had elevated mean diffusivity within 1 week of injury, at return to play, and 1 year later, compared with controls. In athletes with concussion, cerebral blood flow was elevated soon after concussion, normal at return to play, and decreased 1 year later, relative to controls. Global functional connectivity increased and white matter fractional anisotropy decreased near the time of injury and at return to play, but these measures did not significantly differ from those of controls at 1 year.

The study did not capture MRI changes between return to play and 1 year later. In addition, MRI changes might be influenced by a lack of training before resuming play, as well as by exertion and subconcussive impacts after returning to play, the authors noted.

The Canadian Institutes of Health Research, the Canadian Institute for Military and Veterans Health Research, and Siemens Healthineers Canada supported the study. Siemens makes the MRI equipment used in the study. Dr. Churchill and colleagues had no relevant disclosures.

SOURCE: Churchill NW et al. Neurology. 2019 Oct 16. doi: 10.1212/WNL.0000000000008523.

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