Are athletes returning to play too soon after concussion?

Sports-related postconcussion changes in cerebral blood flow and white matter identified on MRI persist in athletes up to one year after injury, according to a study published March 12 in Neurology.

The results suggest that athletes may not be ready to resume participation in their sport as soon as desired, wrote a team led by Nathan Churchill, PhD, of Unity Health in Toronto, Canada.

"[Our] results support [the finding that athletes may have] incomplete recovery of brain physiology at medical clearance," the group noted.

Medical clearance for return to play after sports-related concussion is based on clinical assessment, but it has remained unclear whether athletes' brain physiology is entirely healed to preinjury baseline at the time of this clearance, the researchers explained. Churchill's group investigated whether athletes who experienced concussion showed functional and structural MRI brain changes compared with preinjury levels that persisted beyond medical clearance; the secondary objectives of their research were to test whether post-concussion changes exceed uninjured brain variability and to correlate MRI findings with clinical recovery time.

The team conducted a study that initially included 187 healthy athletes without a history of psychiatric, neurologic, or sensory-motor conditions recruited from a university sport medicine clinic. It collected clinical and MRI data at a preseason baseline time point, and those who were later concussed were reassessed at one to seven days after they sustained the injury, immediately after they returned to play, and one to three months and one year after they resumed their sport. Concussed athletes were paired with a matched control group of uninjured athletes. Churchill and colleagues assessed postconcussion changes in MRI measures of cerebral blood flow, white matter mean diffusivity, and fractional anisotropy.

In the final analysis, the group compared 25 athletes with concussion and follow-up imaging (average age, 20 years; 56% male, 44% female) to 27 controls (average age, also 20 years; 44% male and 56% female).

Churchill's team reported that concussed athletes showed statistically significant changes on MRI from baseline imaging, including reduced blood flow to the frontal and insular regions of the brain, reduced white matter integrity, and reduced fractional anisotropy in the brain's corona radiata and internal capsule -- all of which have been linked to cognitive decline and neurodegenerative disorders. The investigators found that these effects persisted beyond athletes' return to play, and that athletes with longer recovery periods showed significantly greater changes in medial temporal cerebral blood flow.

The study offers "direct evidence of persistent postconcussion changes in CBF and white matter at return to play and up to one year later," the researchers concluded.

The complete article can be found here.