Myelin Water Fraction Is Transiently Reduced after a Single Mild Traumatic Brain Injury – A Prospective Cohort Study in Collegiate Hockey Players
February
Myelin Water Fraction Is Transiently Reduced after a Single Mild Traumatic Brain Injury - A Prospective Cohort Study in Collegiate Hockey Players
Alexander D. Wright 0 1
Michael Jarrett 0 1
Irene Vavasour 0 1
Elham Shahinfard 0 1
Shannon Kolind 0 1
Paul van Donkelaar 0 1
Jack Taunton 0 1
David Li 0 1
Alexander Rauscher 0 1
☯ These authors contributed equally to this work. 0 1
0 1
0 1 MD/PhD Program, University of British Columbia , Vancouver , Canada , 2 Southern Medical Program, University of British Columbia Okanagan , Kelowna , Canada , 3 Department of Experimental Medicine, University of British Columbia , Vancouver , Canada , 4 UBC MRI Research Centre, University of British Columbia , Vancouver , Canada , 5 Faculty of Medicine, Division of Neurology, University of British Columbia , Vancouver , Canada , 6 School of Health and Exercise Sciences, University of British Columbia Okanagan , Kelowna , Canada , 7 Faculty of Medicine, Division of Sports Medicine, University of British Columbia , Vancouver , Canada , 8 Faculty of Medicine, Department of Radiology, University of British Columbia , Vancouver , Canada , 9 Department of Pediatrics, Division of Neurology, University of British Columbia , Vancouver , Canada
1 Editor: Fernando de Castro, Instituto Cajal-CSIC , SPAIN
Impact-related mild traumatic brain injuries (mTBI) are a major public health concern, and remain as one of the most poorly understood injuries in the field of neuroscience. Currently, the diagnosis and management of such injuries are based largely on patient-reported symptoms. An improved understanding of the underlying pathophysiology of mTBI is urgently needed in order to develop better diagnostic and management protocols. Specifically, dynamic post-injury changes to the myelin sheath in the human brain have not been examined, despite 'compromised white matter integrity' often being described as a consequence of mTBI. In this preliminary cohort study, myelin water imaging was used to prospectively evaluate changes in myelin water fraction, derived from the T2 decay signal, in two varsity hockey teams (45 players) over one season of athletic competition. 11 players sustained a concussion during competition, and were scanned at 72 hours, 2 weeks, and 2 months post-injury. Results demonstrated a reduction in myelin water fraction at 2 weeks post-injury in several brain areas relative to preseason scans, including the splenium of the corpus callosum, right posterior thalamic radiation, left superior corona radiata, left superior longitudinal fasciculus, and left posterior limb of the internal capsule. Myelin water fraction recovered to pre-season values by 2 months post-injury. These results may indicate transient myelin disruption following a single mTBI, with subsequent remyelination of affected neurons. Myelin disruption was not apparent in the athletes who did not experience a concussion, despite exposure to repetitive subconcussive trauma over a season of collegiate hockey. These
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Data Availability Statement: All relevant data are
contained within the paper and its Supporting
Information files.
Funding: This research was funded by a London
Drugs Award for Research Excellence in Radiology
(no grant number) and by a New Investigator Award
to Alexander Rauscher from the Canadian Institutes
for Health Research (CIHR, grant #
201109MSH261306-183304). Alexander Rauscher is also a
Canada Research Chair in Developmental
Neuroimaging. Alexander D. Wright was supported
by the Vanier Canada Graduate Scholarships
program. No persons other than the listed authors
had substantial scientific input into this study. The
funders had no role in study design, data collection
and analysis, decision to publish, or preparation of
the manuscript.
findings may help to explain many of the metabolic and neurological deficits observed
clinically following mTBI.
Introduction
Impact-related mild traumatic brain injuries (mTBI) are a growing public health concern
globally, with major causes including sports, motor vehicle accidents, falls, and assaults. The
Centers for Disease Control and Prevention estimate that approximately 1.6–3.8 million mTBI
occur annually in the United States alone [
1
]. Symptoms of concussion, a form of mTBI, are
thought to result from mild diffuse axonal injury (DAI) that is not detectable on conventional
computed tomography or magnetic resonance imaging (MRI). Currently, the diagnosis and
management of this broadly defined and poorly understood injury are based on clinical
observation and patient-reported symptoms, despite numerous recent efforts towards the
development of objective tools to link functional deficits with quantifiable structural changes. While
the majority (80–90%) of individuals with mTBI symptoms recover in 7–10 days, a subset of
individuals are left with persistent disability for months to years [
2
]. Furthermore, emerging
evidence has suggested a possible link between clinically mani (...truncated)