Longitudinal white-matter abnormalities in sports-related concussion: A diffusion MRI study
Wu YC, Harezlak J, Elsaid NMH, Lin K, Wen Q, Mustafi SM, Riggen LD, Koch KM, Nencka AS, Meier TB, Mayer AR, Wang Y, Giza CC, DiFiori JP, Guskiewicz KM, Mihalik JP, LaConte SM, Duma SM, Broglio SP, Saykin AJ, McCrea MA, McAllister TW
Neurology. 2020 Jul 8. Epub ahead of print.
Full Text Freely Available
Take-Home Message
Athletes with a concussion have altered white matter, which persisted for up to 6 months post-injury and related to prolonged recovery and worse sign and symptom severity.
Summary
Clinical assessment tools are useful in concussion management; however, the time course for full pathophysiology recovery remains unclear. Diffusion tensor imaging (DTI) is an imaging method to detect changes in white matter microstructure of the brain. This type of imaging offers a more objective marker for full recovery; however, few prospective longitudinal studies have used this type of imaging among athletes. Therefore, the authors followed 219 collegiate athletes to determine if white-matter abnormalities exist after an athlete becomes asymptomatic after a concussion and if those abnormalities relate to clinical outcomes. The athletes represented 3 cohorts that completed the NCAA CARE Consortium protocol by July 2018. Eighty-two athletes had a diagnosed concussion, 68 matched athletes represented contact-sport controls, and 69 matched athletes served as non-contact controls. The researchers matched contact sports and non-contact controls to athletes with a concussion according to age, sex, education, and Weschler Test of Adult Reading scores. Contact sport controls were also matched on prior concussion, type of sport, and position. All athletes had a clinical assessment at the start of the study (baseline) that included a standard assessment of concussion and sign and symptoms checklist (SCAT), balance errors scoring system (BESS), and Brief Symptom Inventory (BSI). They also received clinical and imaging assessments at 4 times: 1) 24-48 hours post-concussion, 2) when the athlete with a concussion became asymptomatic, 3) 7 days after unrestricted return to play, 4) 6 months post-injury.
The athletes with a concussion scored worse on all the clinical assessments at the 24-48-hour time point compared with both control groups. Athletes with a concussion had more evidence of microstructural destruction of the white matter (e.g., cellular swelling, demyelination, brain edema; based on DTI-derived mean diffusivity) compared to the controls at each time point. While the white matter differences between athletes with concussion and controls decreased with time, part of the corpus callosum had persistent differences between groups. The authors observed no differences in DTI imaging metrics between the control groups. Lastly, greater microstructural destruction within the first day or two after a concussion was associated with worse sign and symptom severity as well as prolonged recovery time.
Viewpoints
The authors found that white matter differences persisted after an athlete with a concussion returned to play even though clinical tests returned to a level similar to matched controls by 7 days of unrestricted return to play. Currently, it is still unclear if these structural findings return to normal. However, they might since this study included people with a prior concussion and still detected differences between groups. Additionally, it was alarming to see that the most affected region of the brain was the corpus callosum. The corpus callosum is in the center of the brain, which is likely affected due to the typical mechanism of a concussion (acceleration-deceleration in the frontal plane). However, the function of the corpus callosum is to foster communication between the left and right hemispheres of the brain. This is necessary to perform both the mental and physical components of sport. For example, an athlete needs the ability to perceive depth to see how far to pass a ball or how much farther they will need to run. This ability is due to the two sides of our brain being able to communicate via the corpus callosum. Currently, medical professionals need to be aware that the microstructure of the brain is altered even after clinical symptoms resolve. We need to educate athletes, parents, and coaches that the brain takes time to heal and ensure best practices are implemented for safe active recovery for return to activity.
Questions for Discussion
If affordable, would you send your more complex concussed athletes’ cases to receive imaging to help check their progress? If the brain microstructure is being affected even after 6 months do you think further monitoring post-concussion or rehabilitation be implemented?
Written by: Jane McDevitt
Reviewed by: Jeffrey Driban
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