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Abstract
Objective To test the hypothesis that concussion-related brain alterations seen at symptomatic injury and medical clearance to return to play (RTP) will have dissipated by 1 year after RTP.
Methods For this observational study, 24 athletes with concussion were scanned longitudinally within 1 week after injury, at RTP, and 1 year after RTP. A large control cohort of 122 athletes were also scanned before the season. Each imaging session assessed global functional connectivity (Gconn) and cerebral blood flow (CBF), along with white matter fractional anisotropy (FA) and mean diffusivity (MD). The main effects of concussion on MRI parameters were evaluated at each postinjury time point. In addition, covariation was assessed between MRI parameters and clinical measures of acute symptom severity and time to RTP.
Results Different aspects of brain physiology showed different patterns of recovery over time. Both Gconn and FA displayed no significant effects at 1 year after RTP, whereas CBF and MD exhibited persistent long-term effects. The effects of concussion on MRI parameters were also dependent on acute symptom severity and time to RTP for all postinjury time points.
Conclusion This study provides the first longitudinal evaluation of concussion focused on time of RTP and 1 year after medical clearance, using multiple different MRI measures to assess brain structure and function. These findings significantly enhance our understanding of the natural course of brain recovery after a concussion.
Glossary
- AFNI=
- Analysis of Functional Neuroimages;
- BW=
- bandwidth;
- CBF=
- cerebral blood flow;
- CI=
- confidence interval;
- CS=
- clinical severity;
- DTI=
- diffusion tensor imaging;
- FA=
- fractional anisotropy;
- FSL=
- fMRIB Software Library;
- FOV=
- field of view;
- FWHM=
- full width at half-maximum;
- Gconn=
- global functional connectivity;
- MD=
- mean diffusivity;
- MNI=
- Montreal Neurological Institute;
- RTP=
- return to play;
- SCAT3=
- Sport Concussion Assessment Tool 3;
- SYM=
- early symptomatic injury;
- TBI=
- traumatic brain injury;
- TE=
- echo time;
- TI=
- inversion time;
- TR=
- repetition time;
- WM=
- white matter
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received January 4, 2019.
- Accepted in final form June 27, 2019.
- © 2019 American Academy of Neurology
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