MRI Shows Acute, Chronic Changes in Myelin in Contact-Sport Athletes

Magnetic resonance imaging detects an increase in myelin water fraction (MWF) in the brains of athletes with mild traumatic brain injury (mTBI), according to an article published in the Journal of Neurosurgery.

Researchers from Florida, Wisconsin, Rhode Island, and Massachusetts performed a small nonrandomized, nonblinded prospective study to quantify changes in the MWF by using the MR imaging technique, multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT). The researchers sought to visualize acute and chronic white matter changes after mTBI.

The subjects included 1 collegiate rugby player and 11 collegiate football players (the contact sport player [CSP] cohort). These subjects were assessed at the time of mTBI diagnosis and 3 months after injury when the acute symptoms of the injury had resolved. Ten age-matched controls also participated, the noncontact sport players (NCSPs). T-tests and a threshold-free cluster enhancement (TFCE) statistical analysis technique were used to identify brain structures with significant changes in the MWF between the CSP and NCSP cohorts and between immediately postinjury and follow-up images obtained in the CSP cohort.

The results showed in the CSP cohort, significantly higher MWFs in the bilateral basal ganglia, anterior and posterior corpora callosa, left corticospinal tract, and left anterior and superior temporal lobe. At the three-month follow-up examination, images from the CSP cohort still showed significantly higher MWFs than those identified on baseline images from the NCSP cohort in the bilateral basal ganglia, anterior and posterior corpora callosa, and left anterior temporal lobe, and also in the bilateral corticospinal tracts, parahippocampal gyrus, and bilateral juxtapositional (previously known as supplemental motor) areas.

In the CSP cohort, a t-test comparing the MWF at the time of injury and three months later showed a significant increase in the overall MWF at follow-up. These increases were greatest in the bilateral basal ganglia and deep white matter. MWF decreases were seen in more superficial white.

"We were surprised by the finding of increased myelin in the contact sports players compared with non-contact sports players at baseline and three months after injury,” coauthor Heather S. Spader, MD, said in a release. “Using the mcDESPOT sequence, we can see that there is a remyelination process after an injury. The next question, however, is to determine if the increased myelin leads to the formation of a type of scar tissue that can cause disorganized signaling in the brain and which can eventually lead to an increased susceptibility to neurodegenerative disorders such as dementia."